A Design project for

Production of Aniline from Ammonolysis of Phenol

Session: 2012-2016

Project Supervisor
Mr. Umair Aslam

Project Members

Zaryab Azeem 2012-CH-13

M. Assad Ayub 2012-CH-29

M. Umar Akhtar 2012-CH-33

M. Farhan 2012-CH-37

Ismail Zahoor 2012-CH-39

Usman Hamid 2012-CH-69

Department of Chemical Engineering

University of Engineering and Technology Lahore-Pakistan

 Production of Aniline from Ammonolysis of Phenol

This project is submitted to the Department of Chemical Engineering, University of

Engineering and Technology Lahore for the partial fulfillment of the requirements for the

Bachelor of Science

In

Chemical Engineering
Session 2012-2016

Internal Examiner: Sign: _______________________

Name: ______________________

External Examiner: Sign: _______________________

Name: ______________________

Department of Chemical Engineering

University of Engineering and Technology Lahore-Pakistan
 DEDICATION

This project work is dedicated to our beloved parents, respected teachers and to all those
people, who are working to make our motherland Pakistan a Prosperous country.
 Acknowledgment
We take on the initiation with the prestige’s name Almighty ALLAH, “lord, designer, builder
of the most complex processing plants; the human body. Its accurate and sophisticated fluid
transportation, gas absorption, filtration, chemical reactions and electronic control systems
with partial mechanical structural capillaries is a product of HIS engineering that we strive to
understand and duplicate” WHO gave us caliber, incentives and courage to complete this
project within prescribed limits and to the HOLY PROPHET MOHAMMAD (S.A.W) who
showed light of knowledge to the humanity as a whole.

The ideas of report writing are usually attributable to all of the group members and the sources,
which helped us a lot to compile it. This is all due to the illuminated guidance of our teachers
as they are builders of our academic carrier, all this could not have been done without their
enlightened supervision and coaching.

We are indebted to our project advisor Mr. Umair Aslam for his worthy discussions,
encouragement, inspiring guidance, remarkable suggestions, keen interest, constructive
criticism & friendly discussions which enabled us to complete this report. He spared a lot of
his precious time in advising & helping us in writing this report.

It is with great pleasure and extreme feelings of obligation that we thank Prof. Dr. Nadeem
Feroz (Dean of Chemical Engineering Department, UET Lahore) and Dr. Ing. Naveed
Ramzan (Chairman of Chemical Engineering Department, UET Lahore) for his constructive
criticism and valuable suggestions during our academic carrier.

Last but not Least, we owe immense sense of gratitude to our parents who not only supported
us financially throughout our education but gave us the strength of character and would always
remain as light for us.
 PREFACE

The design report on the production of Aniline from the ammonolysis of Phenol is a very useful
process used worldwide for the production of MDI.
The design report of our project is made very carefully and honestly, so hopefully the content
is adequate for the basic understanding of the process as each and every aspect is discussed in
detail with clear visual graphics. All the designing and calculations are done by using up to
date correlations of heat transfer, mass transfer and equipment design. This report should also
be useful to the engineers in the chemical engineering department.
All the calculations are done in SI units and the cost estimation is done in dollars. The
references are given in detail at the end of the report so each can be accessed easily.
Separate chapters are devoted to each of the step for the designing of a project including
introduction, process description, material and energy balances and equipment design. For the
good operation and safety purpose, the instrumentation of equipment is done and explained in
a separate chapter. Also, the project cost evaluation is done in the other chapter. Environmental
impacts are also discussed in the last chapter.
Authors
Contents
Contents.................................................................................................................................. 7
1 INTRODUCTION ............................................................................................................ 15
1.1 Aniline ....................................................................................................................... 15
1.2 Polymerization of Aniline ......................................................................................... 15
1.3 Uses of Aniline .......................................................................................................... 15
1.3.1 Preparation of Isocyanates ................................................................................. 15
1.3.2 Rubber Industry ................................................................................................. 15
1.3.3 Fungicides and Herbicides ................................................................................. 15
1.3.4 Material Safety Data Sheet ................................................................................ 15
2 PROCESS SELECTION .................................................................................................. 18
2.1 Comparison between different Production Process .................................................. 18
2.2 Conclusion:................................................................................................................ 18
2.3 Recommendation:...................................................................................................... 18
3 PROCESS DESCRIPTION .............................................................................................. 20
3.1 Process Flow Diagram: ............................................................................................. 20
3.2 Process Description: .................................................................................................. 20
4 CAPACITY SELECTION ............................................................................................... 23
4.1 Market Demand of Aniline ....................................................................................... 23
4.2 Market Demand of Phenol ........................................................................................ 24
4.3 Aniline Producer: ...................................................................................................... 25
5 MATERIAL BALANCE .................................................................................................. 27
5.1 Overall Material Balance .......................................................................................... 27
5.2 Material Balance on Fresh Feed ................................................................................ 28
5.3 Material Balance on Phenol Vaporizer ..................................................................... 28
5.4 Material Balance on Furnace..................................................................................... 28
5.5 Material Balance across Reactor ............................................................................... 30
5.6 Material Balance across Stripper............................................................................... 30
5.7 Material Balance across Drying Column .................................................................. 31
5.8 Material Balance across Aniline Column.................................................................. 32
6 ENERGY BALANCE ...................................................................................................... 35
6.1 Energy Balance on Fresh Feed .................................................................................. 35
6.2 Energy Balance across Vaporizer ............................................................................. 35
6.3 Energy Balance across Furnace................................................................................. 36
6.4 Energy Balance across Reactor ................................................................................. 38
PRODUCTION OF ANILINE FROM PHENOL 7
 6.5 Energy Balance across Stripper................................................................................. 38
6.6 Energy Balance across Drying Column .................................................................... 39
6.7 Energy Balance across Aniline Column.................................................................... 39
7 EQUIPMENT DESIGN ................................................................................................... 41
7.1 Waste Heat HX Design ............................................................................................. 41
7.1.1 Vaporizer type:................................................................................................... 41
7.1.2 Selection: Which one is used & why? ............................................................... 42
7.1.3 Pinch Technology: ............................................................................................. 42
7.1.4 Design Problem:................................................................................................. 45
7.1.5 Nomenclature of Waste Heat Recovery Unit: ................................................... 46
7.1.6 Specification Sheet: ........................................................................................... 53
7.2 Furnace Design .......................................................................................................... 53
7.2.1 Classification of Furnaces: ................................................................................. 55
7.2.2 Design and Operation: ....................................................................................... 56
7.2.3 Selection Criteria: .............................................................................................. 57
7.2.4 Furnace Design: ................................................................................................. 59
7.3 Reactor Design .......................................................................................................... 63
7.3.1 Types of reactors: ............................................................................................... 63
7.3.2 Selection criteria of reactor: ............................................................................... 65
7.3.3 Selected reactor .................................................................................................. 65
7.3.4 Reactor design:................................................................................................... 66
7.3.5 Design Steps: ..................................................................................................... 67
7.3.6 Reaction kinetics: ............................................................................................... 67
7.4 Stripper Design .......................................................................................................... 74
7.4.1 Problem Statement ............................................................................................. 74
7.4.2 Nomenclature ..................................................................................................... 74
7.4.3 Design Steps....................................................................................................... 75
7.4.4 Selection of Tray Type....................................................................................... 75
7.5 Aniline Column Design ............................................................................................. 80
7.5.1 Choice of Column .............................................................................................. 80
7.5.2 Merits of Tray Column ...................................................................................... 80
7.5.3 Types of Tray ..................................................................................................... 81
7.5.4 Designing Steps of Distillation Column ............................................................ 81
7.5.5 Nomenclature: .................................................................................................... 82
7.5.6 Design of Aniline Recovery Column ................................................................. 83

PRODUCTION OF ANILINE FROM PHENOL 8

 7.5.7 Specification Sheet............................................................................................. 89
7.6 Condenser Design ..................................................................................................... 90
7.6.1 Condensation...................................................................................................... 90
7.6.2 Selection Criteria for Condenser ........................................................................ 91
7.6.3 Design of Condenser .......................................................................................... 92
8 HAZOP STUDY............................................................................................................... 98
8.1 Hazard and operability studies: ................................................................................. 98
8.2 Basic Principles: ........................................................................................................ 98
8.3 Vessel – Ammonia vaporizer .................................................................................... 99
9 ENVIRONMENTAL IMPACT ASSESSMENT ........................................................... 103
9.1 Environmental Impact Assessment ......................................................................... 103
9.2 Importance of EIA ................................................................................................... 103
9.3 Contents of an EIA report ....................................................................................... 103
9.4 Step Wise Structure of EIA ..................................................................................... 103
9.4.1 Preliminary Activities & TOR ......................................................................... 103
9.4.2 Scoping ............................................................................................................ 104
9.4.3 Baseline Studies ............................................................................................... 104
9.5 Alternatives ............................................................................................................. 104
9.5.1 Impact Prediction ............................................................................................. 104
9.5.2 Impact Assessment........................................................................................... 104
9.5.3 Mitigation ......................................................................................................... 104
9.6 EIS Preparation/Review .......................................................................................... 105
9.6.1 Public Consultation and Decision Making ...................................................... 105
9.6.2 Project Monitoring ........................................................................................... 105
9.7 EIA of NH3 Removal Section Air Emissions.......................................................... 105
9.8 Water Emissions...................................................................................................... 106
9.9 Noise Pollution ........................................................................................................ 106
9.10 Potential Health Effect ............................................................................................ 107
9.11 First Aid Measure. ................................................................................................... 107
9.12 Fire Fighting Measure ............................................................................................. 107
9.13 Accidental Release Measure ................................................................................... 108
9.14 Handling and Storage .............................................................................................. 108
9.15 Exposure Control/ Personal Protection ................................................................... 108
10 ASPEN HYSYS SIMULATION ................................................................................ 110
10.1 Keywords ................................................................................................................ 110

PRODUCTION OF ANILINE FROM PHENOL 9

 10.2 Objectives ................................................................................................................ 110
10.3 Introduction ............................................................................................................. 110
10.4 Methodology ........................................................................................................... 111
10.4.1 Modeling Strategy............................................................................................ 111
10.4.2 Simulation Approach ....................................................................................... 111
10.4.3 Analysis............................................................................................................ 129
10.5 Results and Discussion ............................................................................................ 130
10.6 Conclusions and Recommendations........................................................................ 130
11 COST ESTIMATION ................................................................................................. 132
11.1 Overview ................................................................................................................. 132
11.2 Purchased Equipment .............................................................................................. 133
12 INSTRUMENTATION .............................................................................................. 135
12.1 Instrument................................................................................................................ 135
12.2 Main Process variables & their Control .................................................................. 135
12.3 Control Loops .......................................................................................................... 136
12.3.1 Feed Forward Control Loop............................................................................. 137
12.3.2 Feed Backward Control Loop .......................................................................... 137
12.3.3 Ratio Control.................................................................................................... 137
12.3.4 Auctioneering Control Loop ............................................................................ 137
12.3.5 Split Range Loop ............................................................................................. 137
12.4 Control Scheme on Heat Exchanger ....................................................................... 138
12.4.1 Control objective .............................................................................................. 138
12.4.2 Manipulated variable: ...................................................................................... 138
12.4.3 Controller: ........................................................................................................ 138
12.4.4 Final control element: ...................................................................................... 138
12.5 Feedback Temperature Control Loop ..................................................................... 138
REFERENCES ...................................................................................................................... 139

PRODUCTION OF ANILINE FROM PHENOL 10

PRODUCTION OF ANILINE FROM PHENOL 11
Tables
Table 1: Material Safety Data Sheet ........................................................................................ 15
Table 2: Process Selection Comparison ................................................................................... 18
Table 3: Imports of Aniline...................................................................................................... 23
Table 4: Capacity of Phenol ..................................................................................................... 24
Table 5: Import of Phenol ........................................................................................................ 24
Table 6: Overall Material Balance ........................................................................................... 27
Table 7: Material Balance on Fresh Feed ................................................................................ 28
Table 8: Material Balance of reactor outlet gases .................................................................... 28
Table 9: Material Balance of Furnace ...................................................................................... 29
Table 10: Material Balance Components ................................................................................. 29
Table 11: Material Balance the Reactor................................................................................... 30
Table 12: Material Balance of Stripper .................................................................................... 31
Table 13: Material Balance of Drying Column ....................................................................... 32
Table 14: Aniline Recovery Unit ............................................................................................. 33
Table 15: WHRU Heat Balance ............................................................................................... 36
Table 16: WHRU Heat Balance ............................................................................................... 36
Table 17: Furnace Conditions .................................................................................................. 36
Table 18: Average Cp Calculations ......................................................................................... 37
Table 19: Vaporizer Type ........................................................................................................ 44
Table 20: Heat Exchanger Requirement .................................................................................. 44
Table 21: WHRU Specification Sheet ..................................................................................... 53
Table 22: Physical Properties at top & bottom ........................................................................ 84

PRODUCTION OF ANILINE FROM PHENOL 12

Figures
Figure 1: Imports of Aniline .................................................................................................... 23
Figure 2: Temperature Profile .................................................................................................. 35
Figure 3: Tube Spec DQ Kern ................................................................................................. 47
Figure 4: Jh factor for ho DQ Kern .......................................................................................... 49
Figure 5: Jf Factor for Pressure Drop Coulson Richardson ..................................................... 50
Figure 6: Tube Bundle Dia Coulson Richardson ..................................................................... 50
Figure 7: Convective Heat Transfer Coefficient DQ Kern ...................................................... 51
Figure 8: Ammonia Vaporizer Instrumentation ....................................................................... 99
Figure 10: Process Flow Diagram of Halcon Process ........................................................... 110
Figure 11:Ammonia Pre-heater and vaporizer ....................................................................... 112
Figure 12: Phenol Pre-heater and vaporizer........................................................................... 113
Figure 13:Phenol Superheater ................................................................................................ 114
Figure 14: Ammonia Superheater .......................................................................................... 114
Figure 15: Reactor Inputs....................................................................................................... 115
Figure 16: Reactor worksheet ................................................................................................ 115
Figure 17: Reactor's stream composition ............................................................................... 116
Figure 18: Reactor Summary ................................................................................................. 116
Figure 19: Stripper specification ............................................................................................ 117
Figure 20: Pressure vs Tray position of column .................................................................... 118
Figure 21: Sizing of main tower ............................................................................................ 118
Figure 22: Sizing of Reboiler ................................................................................................. 119
Figure 23: Column Worksheet ............................................................................................... 119
Figure 24: Column streams composition ............................................................................... 120
Figure 25: Component flowrates ........................................................................................... 120
Figure 26: Auto Water Draws (AWD)................................................................................... 121
Figure 27: Column Internals .................................................................................................. 121
Figure 28: Flashing results ..................................................................................................... 122
Figure 29: E-105 Cooler ........................................................................................................ 122
Figure 30: Input specifications for Aniline Rec-1 ................................................................. 123
Figure 31: Temperature profile of Aniline Rec-1 .................................................................. 123
Figure 32: Aniline Rec-1 tower sizing ................................................................................... 124
Figure 33: Aniline Rec-1 streams results ............................................................................... 124
Figure 34: Aniline Rec-1 reboiler & condenser sizing .......................................................... 125
Figure 35: Aniline Rec-1 streams composition ..................................................................... 125
Figure 36: Components recovery in Aniline Rec-1 ............................................................... 126
Figure 37: VL flowrate in condenser & reboiler ................................................................... 126
Figure 38: Aniline mixer-101 ................................................................................................ 127
Figure 39: Aniline storage cooler .......................................................................................... 127
Figure 40: Aniline storage tank.............................................................................................. 128
Figure 41: Aniline storage tank results summery .................................................................. 128
Figure 42: Energy target for Halcon process ......................................................................... 129
Figure 43: Pinch Analysis over the plant ............................................................................... 130

PRODUCTION OF ANILINE FROM PHENOL 13

 CHAPTER 1

INTRODUCTION

PRODUCTION OF ANILINE FROM PHENOL 14

 INTRODUCTION

1 INTRODUCTION
1.1 Aniline
Aniline, phenyl-amine or amino-benzene is a toxic organic compound with the formula
C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical
aromatic amine. Like most volatile amines, it possesses the odor of rotten fish. It ignites readily,
burning with a smoky flame characteristic of aromatic compounds[1].
1.2 Polymerization of Aniline
The oxidation of aniline and can result in the formation of new C-N bonds.

1.3 Uses of Aniline

1.3.1 Preparation of Isocyanates
Aniline is used to make chemical substances called isocyanates. Why are isocyanates
important? Isocyanates are needed in the production of polyurethane. Polyurethane is used in
making plastic, building thermal foam insulation for buildings and for refrigerators, and
making spandex fibers for athletic clothing.
1.3.2 Rubber Industry
We use rubber for so many things - to make tire for our cars, to balls used for sports, and a lot
of latex products like gloves and balloons. In order to make rubber, we need aniline to produce
the necessary chemical compounds used to make rubber. Aniline is needed to make
phenylenediamine and diphenylamine, which are additives to rubber[2].
1.3.3 Fungicides and Herbicides
In the agricultural industry, weeds can pop up, and crops can experience infection due to
organisms. Because of these problems, fungicides and herbicides are needed. Aniline is a
chemical substance that is needed to manufacture the herbicides to kill weeds and fungicides
to kill organisms that are harmful to plants.
1.3.4 Material Safety Data Sheet
Table 1: Material Safety Data Sheet

CAS Registry Number 62-53-3

Chemical formula C6H5NH2
Molar mass 93.13 g/mol
Appearance Colorless to yellow liquid
Density 1.0217 g/mL, liquid
Melting point −6.3 °C (20.7 °F; 266.8 K)

PRODUCTION OF ANILINE FROM PHENOL 15

 INTRODUCTION

Boiling point 184.13 °C (363.43 °F; 457.28 K)

Solubility in water 3.6 g/100 mL at 20 °C
Vapor pressure 0.6 mmHg (20° C)[1]
Basicity (pKb) 9.13 [2]
Viscosity 3.71 cP (3.71 mPa·s at 25 °C
Std enthalpy of combustion(ΔcHo298) -3394 kJ/mol

Main hazards Potential occupational carcinogen

Safety data sheet See: data page
EU classification
T N
R-phrases R23/24/25 R40 R41 R43R48/23/24/25 R68 R50
S-phrases (S1/2) S26 S27 S36/37/39S45 S46 S61 S63
Flash point 70 °C (158 °F; 343 K)
Auto ignition temperature 770 °C (1,420 °F; 1,040 K)

Explosive limits 1.3%-11%[1]

Lethal dose or concentration (LD, LC):

LC50 (Median concentration) 175 ppm (mouse, 7 hr)[3]
LCLo (Lowest published) 250 ppm (rat, 4 hr)
180 ppm (cat, 8 hr)[3]

US health exposure limits (NIOSH)

PEL (Permissible) TWA 5 ppm (19 mg/m3) [skin][1]
REL (Recommended) Ca [potential occupational carcinogen][1]

PRODUCTION OF ANILINE FROM PHENOL 16

 CHAPTER 2

PROCESS SELECTION

PRODUCTION OF ANILINE FROM PHENOL 17

 PROCESS SELECTION

2 PROCESS SELECTION
2.1 Comparison between different Production Process
Table 2: Process Selection Comparison

Aniline Nitrobenzene Phenol Chloro-benzene Benzene

production from

Other Reactants H2 NH3 NH3 NH3

Reaction C6H5NO2 + 3H2 C6H5OH + 3NH3 C6H5Cl + NH3 C6H6 + NH3

C6H5NH2 + C6H5NH2 + H2O C6H5NH2 + C6H5NH2 +
2H2O NH4Cl H2

Catalyst Nickel Sulphide Al2O3.SiO2 + CuCl + NH4Cl NiO/Ni

(Niewland) Promoter:
Mg,B,Al,Ti
Zirconium
(Oxides)
oxide

Conditions 300-475 oC 425 oC / 180-220 oC / 350 oC /

200 bar 60-75 bar 300 bar

Heat of Reaction -443 KJ/mol -544 KJ/mol -385 KJ/mol - 418 KJ/mol

Reactor Type Fixed Bed Fixed Bed Tubular Reactor Fixed Bed
Reactor Reactor Reactor

Selectivity 99% 95% 91% 97%

Conversion 99.7% 97% Specific 13%

By Products H2O H2O + NH4Cl H2

Diphenylamine

2.2 Conclusion:
a. We figure out that there are lots of processes to produce aniline.
b. The production of aniline is takes an active part in America and china.
c. Far away aniline production is not exist.
2.3 Recommendation:
The process aniline production from ammonolysis of phenol is the best substitute for the
production of Aniline due to its cheap raw materials and it’s highly profit associating it to the
other two substitutes.[3] Lately phenol is being used in aniline developed processes in some
countries.

PRODUCTION OF ANILINE FROM PHENOL 18

 CHAPTER 3

PROCESS DESCRIPTION

PRODUCTION OF ANILINE FROM PHENOL 19

 PROCESS DESCRIPTION

3 PROCESS DESCRIPTION
3.1 Process Flow Diagram:

3.2 Process Description:

Phenol (1) at its melting point of 410C and 16 bar. Phenol is vaporize (5) in waste heat boiler
(WHU-1) at 3160C by using heat of reactor outlet gases (8) which are at 4250C. By using energy
balance we came to know that after exchanging heat with boiling phenol reactor outlet gases
reduced to 349 0C (8’) . (WHU-1) is kettle type reboiler. Liquid ammonia (2) is entered at 25
0
C in vaporizer (V-02). Ammonia is vaporized (3) at its boiling point 60 0C and 16 bar pressure.
Excess ammonia from the stripping section (12) is mixed in mixer (M-01) with fresh ammonia
(3) from vaporizer (V-02) and send to the (HX-02) for superheating. (HX-02) is a type of
furnace in which ammonia from (M-01) (4) is super-heated to 4250C and then fed to the mixer
(M-02) through (4’). Vaporized Ammonia from (HX-02) (4’) and phenol (SH-01) (6) are fed
to the mixer (M-2) where they are mixed and then fed to the reactor (7) (R-1). Mixed feed (M-
02) containing ammonia and phenol are fed to the reactor(R-1) where ammonylsis takes place.
This reactor is actually an adiabatic reactor containing a fixed bed of Alumina and Silica as a
catalyst. Reaction takes place at 425-435 0C and 1.6 MPa with ammonia in excess (ammonia
to phenol ratio is 20:1). The reaction is mildly exothermic which can raise the temperature up
to 4350C that will not cause any decomposition of ammonia[4].
C6 H6 − OH + NH3 → C6 H6 − NH2 + H2 O
C6 H6 − OH + C6 H6 − NH2 → C6 H6 − NH2 − C6 H6 + H2 O

PRODUCTION OF ANILINE FROM PHENOL 20

 PROCESS DESCRIPTION

a. Selectivity: 95%
b. Conversion: 97%
c. By product: diphenylamine 5%
By using energy balance we came to know that after exchanging heat with boiling phenol
reactor outlet gases reduced to 349oC. The temperature of the waste heat recovery unit effluent
stream (8’) is reduced up to 38 0C by heat exchanger (HX-01). Now the cold effluent stream
(HX-01) feed into stripper (S-01) and unreacted ammonia (10) leave from top of the stripper
which then fed to compressor to increase the pressure of gaseous. Now the bottom stream (11)
is allowed to pass through a throttle valve (TV-1) where sudden pressure reduction takes place
and water plus organic compounds containing products and by products are condensed at the
bottom[5]. Stream (13) introduced in dehydrator (DH-01) where overhead stream (15)
containing water and trace amount of aniline. Bottom stream (14) is introduced in Distillation
Column (DC-01) for further processing. The bottom fraction (14) dehydrator is then gone
through distillation column (DC-01) to recover pure aniline (19) from top and Diphenyl amine
(20) at the bottom.

PRODUCTION OF ANILINE FROM PHENOL 21

 CHAPTER 4

CAPACITY SELECTION

PRODUCTION OF ANILINE FROM PHENOL 22

 CAPACITY SELECTION

4 CAPACITY SELECTION

4.1 Market Demand of Aniline

List of supplying markets for a product imported by Pakistan
Product: 292141 Aniline and its salts
Sources: ITC calculations based on UN COMTRADE statistics.
Table 3: Imports of Aniline

Unit : US Dollar Thousand

Exporters Imported Imported Imported Imported Imported
value in 2010 value in 2011 value in 2012 value in 2013 value in 2014
World 143 249 97 147 295
India 13 152 65 67 165
China 130 96 31 79 124
Japan 0 0 0 0 5
UK 0 0 0 0 1
Germany 0 0 0 1 0

Figure 1: Imports of Aniline

PRODUCTION OF ANILINE FROM PHENOL 23

 CAPACITY SELECTION

Table 4: Capacity of Phenol

4.2 Market Demand of Phenol

List of supplying markets for a product imported by Pakistan
Product: 290711 Phenol (hdroxybenzene) and its salts[6]

Sources: ITC calculations based on UN COMTRADE statistics.

Table 5: Import of Phenol

Unit : US Dollar thousand

Exporters Imported Imported Imported Imported Imported
value in 2010 value in 2011 value in value in value in
2012 2013 2014
World 5081 5556 4527 4616 4051
Taipei, Chinese 2142 4441 3096 4485 3954
Korea, Republic of 519 248 568 77 62
India 2 16 0 0 21
China 112 36 31 31 9
Germany 18 141 44 22 2
United Kingdom 10 0 0 0 2
Korea, Democratic 0 30 0 0 0
People's Republic of
United Arab 20 0 0 0 0
Emirates
South Africa 2227 644 787 0 0
Spain 29 0 0 0 0

PRODUCTION OF ANILINE FROM PHENOL 24

 CAPACITY SELECTION

4.3 Aniline Producer:

Producer Capacity (millions of lb.)/year Capacity 1000 ton/year

BASF 583 265
Dow 429 195
Huntsman ICI 660 300
DuPont 314.6 143
Mitsui 341 155
Bayer 66 40
Total 2393.6 1088
a. We are going to target Bayer’s market. So our plant capacity will be 40,000 ton/year

PRODUCTION OF ANILINE FROM PHENOL 25

 CHAPTER 5

MATERIAL BALANCE

PRODUCTION OF ANILINE FROM PHENOL 26

 MATERIAL BALANCE

5 MATERIAL BALANCE
5.1 Overall Material Balance
Overall Material Contain As follow
Table 6: Overall Material Balance

Inlet Flowrate Outlet Flowrate

Phenol 5127.0000 Kg/hr 153.8100 Kg/hr
54.5426 Kmol/hr 1.6363 Kmol/hr
Ammonia 18544.4681 Kg/hr 17690.0317 Kg/hr
1090.8511 Kmol/hr 1040.5901 Kmol/hr
Water Kg/hr 952.3130 Kg/hr
Kmol/hr 52.9063 Kmol/hr
Aniline Kg/hr 4428.2554 Kg/hr
Kmol/hr 47.6156 Kmol/hr
DPA Kg/hr 447.0580 Kg/hr
Kmol/hr 2.6453 Kmol/hr
Total 23671.4681 Kg/hr 23671.4681 Kg/hr
1145.3936 Kmol/hr 1145.3936 Kmol/hr

PRODUCTION OF ANILINE FROM PHENOL 27

 MATERIAL BALANCE

5.2 Material Balance on Fresh Feed

Material Balance of fresh feed contain recycle – reactor inlet.[7]
Table 7: Material Balance on Fresh Feed

Fresh Feed

Flow Mol/mass
rate Frac
Phenol 5127.0000 Kg/hr 0.8572
Ammonia 854.4364 Kg/hr 0.1428
Water
Aniline
DPA
Total 5981.4364 Kg/hr 1.0000
104.8035 Kmol/hr 1.0000

5.3 Material Balance on Phenol Vaporizer

Material balances of this equipment is very simple and easy one fresh phenol enter into system
at 41 degree centigrade at its melting point and we have to pre heat it at 316 degree centigrade
then we have to provide latent heat at this temperature[8].
And reactor outlet gases contain different composition as follow:
Table 8: Material Balance of reactor outlet gases

PRODUCT

Flow rate Mol/mass Frac.

Phenol 153.8100 Kg/hr 0.0065

Ammonia 17690.0317 Kg/hr 0.7473

Water 952.3130 Kg/hr 0.0402

Aniline 4428.2554 Kg/hr 0.1871

DPA 447.0580 Kg/hr 0.0189

Total 23671.4681 Kg/hr 1.0000

5.4 Material Balance on Furnace

Reactions

H2 + ½ O2 → H2O
CH4 + 2O2 → CO2 + 2H2O

PRODUCTION OF ANILINE FROM PHENOL 28

 MATERIAL BALANCE

C2H6 + 3.5O2 → 2CO2 +3H2O

C3H8 + 5O2 → 3CO2 + 4H2O

Table 9: Material Balance of Furnace

Fuel Natural
Lower Heating Value 47141 (KJ/Kg)
Composition Mass %
Hydrogen 0.5
Methane 95
Ethane 3.2
Propane 1.3
Fuel Natural

Take 20 % excess air:

Air to fuel ratio (G) = 9.7 kg/kg (at 0 % excess)

Air to fuel ratio (G) = 11.8 kg/kg (at 20 % excess)

Total Required heat duty = m ∗ Cp ∗ (∆T)

= (1091) ∗ (1.5343E4)

= 1.67E7 kJ/hr

Furnace Efficiency = 70 %

Heat liberated by the fuel = 1.67E7/0.7 = 2.39E7 kJ/kg

Amount of fuel = 2.39E7/47141 = 206.65 kg/hr

Amount of air required = 6.026E3 kg/hr

Table 10: Material Balance Components

components F (kg/hr) Components F (kg/hr)

H2 2.53 CO2 524.07

CH4 481.78 H2O 1037.56

C2H6 16.22 N2 4760.80

C3H\8 6.59 O2 210.92

Air N2=4760.80

O2=1265.53

Input 6533.45 Output 6533.45

PRODUCTION OF ANILINE FROM PHENOL 29

 MATERIAL BALANCE

5.5 Material Balance across Reactor

Our material balance start with assume the initial moles of phenol which enter into the reactor
where beside it we introduce ammonia in such a way that molar ratio of ammonia to phenol is
20:1. Then 97% conversion is assumed based on patent and 95 % of selectivity of that of aniline
is also assumed then further process is carried out and in the end we apply goal seek function
from excel which provide us the our desired aniline in the product.[7][8]
Table 11: Material Balance the Reactor

Input Output
Components Molar Flow rate Components Molar Flow rate
(kmol/hr) (Kmol/hr)
Phenol 55 phenol 1.65

Ammonia 1090 Ammonia 1040

Aniline - Aniline 47

Water - water 52

Total Moles 1145 Kmol/hr DPA 2.5

Total mass 23671 Kg/hr Total Moles 2.74 x 102 Kmol/hr

Temperature 425°C Total Mass 6.794x 103 Kg/hr

Temperature 435°C

5.6 Material Balance across Stripper

Assumption:
1. Ammonia recovery at the top is 99%
2. Water recovery at the top is 0.01%
3. All the heavy non-keys goes to bottom
Overall Column Balance:
F=D+W
F = D + W = 1145.394 kmol/h
Ammonia Balance:
DxNH3 = 0.99 ∗ FzNH3 = 1032.236 kmol/h

WxNH3 = 1042.663 − 1032.236 = 10.427 kmol/h

PRODUCTION OF ANILINE FROM PHENOL 30

 MATERIAL BALANCE

Water Balance:
DxH2 O = 0.01 ∗ FzH2 O = 0.518 kmol/h

WxH2 O = 51.815 − 0.518 = 51.297 kmol/h

Summary of Material Balance:

Table 12: Material Balance of Stripper

Components 𝐅𝐞𝐞𝐝 𝒎̇[Kmol/h] Top 𝒎̇[Kmol/h] Bottom 𝒎̇[Kmol/h]

Phenol 2.727 0.000 2.727

Water 51.815 0.518 51.297
Aniline 44.561 0.000 44.561
DPA 3.627 0.000 3.627
NH3 1042.663 1032.236 10.427
Total 1145.394 1032.754 112.640
Temp. [oC] 38 38 191
Pressure [Bar] 13 13 13.054

5.7 Material Balance across Drying Column

Assumption:
1. Ammonia recovery at the top is 100%
2. Water recovery at the bottom is 0 %
3. All the heavy non-keys goes to bottom
Overall Column Balance:
F=D+W
F = D + W = 112.640 kmol/h
Ammonia Balance:
DxNH3 = 1.00 ∗ FzNH3 = 10.427 kmol/h

WxNH3 = 10.427 − 10.427 = 0.00 kmol/h

PRODUCTION OF ANILINE FROM PHENOL 31

 MATERIAL BALANCE

Water Balance:
WxH2 O = 0.00 ∗ FzH2 O = 0.00 kmol/h

DxH2 O = 51.297 − 0.00 = 51.297 kmol/h

Summary of Material Balance:

Table 13: Material Balance of Drying Column

Components 𝐅𝐞𝐞𝐝 𝒎̇[Kmol/h] Top 𝒎̇[Kmol/h] Bottom 𝒎̇[Kmol/h]

Phenol 2.727 0.000 2.727

Water 51.297 51.297 0.000
Aniline 44.561 0.000 44.561
DPA 3.627 0.000 3.627
NH3 10.427 10.427 0.000
Total 112.640 61.7240 50.915
Temp. [oC] 191 98 185.4
Pressure [Bar] 1.01 1 1.013

5.8 Material Balance across Aniline Column

Assumption:
1. Aniline recovery at the top is 97%
2. DPA recovery at the bottom is 99.9 %
3. All the heavy non-keys goes to bottom
Overall Column Balance:
F=D+W
F = D + W = 50.915 kmol/h
Aniline Balance:
Dx𝑎𝑛𝑖𝑙𝑖𝑛𝑒 = 0.97 ∗ Fz𝑎𝑛𝑖𝑙𝑖𝑛𝑒 = 43.188 kmol/h
Wx𝑎𝑛𝑖𝑙𝑖𝑛𝑒 = 44.561 − 43.188 = 1.373 kmol/h

PRODUCTION OF ANILINE FROM PHENOL 32

 MATERIAL BALANCE

DPA Balance:
WxDPA = 0.999 ∗ FzDPA = 3.626 kmol/h
DxDPA = 3.627 − 3.626 = 0.001 kmol/h
Summary of Material Balance:
Table 14: Aniline Recovery Unit

Components 𝐅𝐞𝐞𝐝 𝒎̇[Kmol/h] Top 𝒎̇[Kmol/h] Bottom 𝒎̇[Kmol/h]

Phenol 2.727 1.823 0.904

Aniline 44.561 43.188 1.373
DPA 3.627 0.001 3.626
Total 50.915 45.012 5.903
Temp. [oC] 185.4 183.8 215
Pressure [Bar] 1.013 1 1.016

PRODUCTION OF ANILINE FROM PHENOL 33

 CHAPTER 6

ENERGY BALANCE

PRODUCTION OF ANILINE FROM PHENOL 34

 ENERGY BALANCE

6 ENERGY BALANCE
6.1 Energy Balance on Fresh Feed

We are assume that at 25 0C the enthalpy of liquid ammonia is zero as a reference point. As
ammonia is in liquid state first we pre heat it to its boiling point after that we provide the latent
heat after which we super heat it at 425 0C.[5] And phenol is entering into the system at 41 0C.
We are assuming the solid state of phenol at 25 0C as zero reference state.

So energy of the inlet phenol is:

H = 1.9681E+03 J/mol
6.2 Energy Balance across Vaporizer
Shell side energy balance are as follow.
Sensible heat transfer: 𝑚 × 𝐶𝑝 × ∆𝑇

Qp = 5127 × (2.55𝐸 + 03) × (275)

= 3.6E+9 J/hr = 1E+06 W
Latent heat transfer: 𝑚 × 𝐻𝑉𝑎𝑝

Qv = 5127 × (3𝐸 + 05)

= 1.7E+09 J/hr = 5E+05 W
Temperature Profile:

Figure 2: Temperature Profile

PRODUCTION OF ANILINE FROM PHENOL 35

 ENERGY BALANCE

Tube side energy balance:

Table 15: WHRU Heat Balance

Cp (J/(mol K)) T (K) Cp×= (25 °C)

NAME Formula MW A B C D E Tmin Tmax

phenol C6H6O 94.113 4.408 0.36338 -6.7E5 -1.2E7 5.57E11 100 1500

aniline C6H7N 93.129 -22.06 0.57313 -4.1E4 1.81E7 -2.7E11 200 1500

DPA C12H11N 169.226 -119.4 1.30600 -1.0E3 5.86E7 -1.7E10 298 1500

Ammonia NH3 33.573 -1.2E2 8.89E5 -7.1E8 1.85E11 100 1500

Water H2O 33.933 -8.4E3 2.98E5 -1.7E8 3.34E12 100 1500

Table 16: WHRU Heat Balance

T in T out Cp dt Molar Flow Heat given

708.4095 621.71756 phenol 1.6683E+04 1.6363E+00 2.7298E+04 KJ/hr
708.4095 621.71756 aniline 1.7806E+04 4.7616E+01 8.4784E+05 KJ/hr
708.4095 621.71756 DPA 3.1191E+04 2.6453E+00 8.2510E+04 KJ/hr
708.4095 621.71756 ammonia 4.0783E+03 1.0406E+03 4.2438E+06 KJ/hr
708.4095 621.71756 water 3.2114E+03 5.2906E+01 1.6990E+05 KJ/hr
o
435.4095 348.71756 C total flow 1.1427E+03 5.3714E+06 KJ/hr

6.3 Energy Balance across Furnace

Table 17: Furnace Conditions

Reference conditions NH3 inlet conditions NH3 outlet conditions

T = 25 ⁰C Ti = 62 ⁰C To = 425 ⁰C

P = 1 Bar P = 16 Bar P = 15.7 Bar

Radiant section efficiency = 70 %

Cross Over Temperature = To – 0.7 ∗ (To – Ti) = 425 – 0.7 ∗ (425 – 62) = 171.2 ⁰C

Average Temperature = (171.2 + 425)/2 = 298 ⁰C

PRODUCTION OF ANILINE FROM PHENOL 36

 ENERGY BALANCE

As a rule of thumb, Ts is taken 38⁰C more than the average temperature.

Ts = 298.15 + 38 = 336.15 ⁰C

∑Q / (αAcpf) = 452713.472 KJ/hr. m2

From appendix, 𝑇g = 1650 ⁰𝐹 = 899 ⁰𝐶

Table 18: Average Cp Calculations

Components Cpi (kJ/kg.K) Mole fraction (Xi) XiCpi

N2 1.198 0.73 0.906891
H2O 2.395 0.160 0.31096
O2 1.097 0.032 0.044571
CO2 1.27 0.083 0.090801
Cpavg 1.353223

Qexhaust = mfuel (1 + G) Cpavg (Tg – Tref) = 507.17 ∗ (1 + 11.88) ∗ (1.353223) ∗ 873

= 7944003 kJ/hr

𝑄𝑎𝑖𝑟 = (Enthalpy of air at room temperature) ∗ (Air Flow rate) = 725 ∗ 6026.33

= 4369094.98kJ/hr

Qfuel = 2 % of Qfuel = 0.02 ∗ 23907347.54 = 478146.95kJ/hr

∑Q = Qfuel + QAir – Qexhaust – Qwall = 19854292.32 kJ/hr

PRODUCTION OF ANILINE FROM PHENOL 37

 ENERGY BALANCE

6.4 Energy Balance across Reactor

Following are the reactions taking place in the reactor:

C6H6O + NH3 C6H6N + H2O

C6H6O + C6H6N C12H11N + H2O
Heat of reactions is -1.2421E+01 KJ/mol and -13.219 KJ/mol respectively.
Heat of formation of the components:
∆Hf = A+B*T+C*T^2
Components Formula MW A B C Hf 298 Hf 500
K K
DiPA C12H11N 169.22 229.1 -0.113 6.79E- 202 189.95
05
Aniline C 6 H7 N 93.12 102.90 -0.064 3.33E- 86.86 79.74
05
Water H2 O 18.01 -238.41 -0.0123 0.0000 -241.80 -243.85
Phenol C 6 H6 O 94.11 -81.25 -0.0613 0.0000 -96.40 -103.11

Cp values of the component:

Cp gas =A+B*T+C*(T^2)+D*(T^3)+E*(T^4) [7]

Name Formula A B C D E Cp*

Phenol C6H6O 4.408 0.36338 -6.04E-05 -1.279E-07 5.587E-11 104.43
Aniline C6H7N -22.062 0.57313 -4.551E-04 1.841E-07 -2.986E-11 112.88
DPA C12H11N -119.40 1.30600 -1.220E-03 5.876E-07 -1.144E-10 176.20

Heat capacity
NH3 Ammonia 33.573 -1.2E-02 8.8906E-05 -7.173E-08 1.859E-11
H2O Water 33.933 -8.4E-03 2.9906E-05 -1.785E-08 3.694E-12

6.5 Energy Balance across Stripper

PRODUCTION OF ANILINE FROM PHENOL 38

 ENERGY BALANCE

𝑛 𝑇
𝐻 = 𝑚̇ [∑ ∫ 𝑥𝑖 𝐶𝑝𝑖 𝑑𝑇 + 𝜆]
𝑖=1 298

T [oC] Pressure [bar] Enthalpy [kJ/h]

38 13 2.295E+7
191 13 2.2214E+7
260 13.05 1.594E+7

6.6 Energy Balance across Drying Column

𝑛 𝑇
𝐻 = 𝑚̇ [∑ ∫ 𝑥𝑖 𝐶𝑝𝑖 𝑑𝑇 + 𝜆]
𝑖=1 298

T [oC] Pressure [bar] Enthalpy [kJ/h]

70 1 3.947E+7
185 1.12 6.48E+7

6.7 Energy Balance across Aniline Column

𝑛 𝑇
𝐻 = 𝑚̇ [∑ ∫ 𝑥𝑖 𝐶𝑝𝑖 𝑑𝑇 + 𝜆]
𝑖=1 298

T [oC] Pressure [bar] Enthalpy [kJ/h]

185 1.15 6.48E+7
231 1.15 7.30E+7

PRODUCTION OF ANILINE FROM PHENOL 39

 CHAPTER 7

EQUIPMENT DESIGN

PRODUCTION OF ANILINE FROM PHENOL 40

 EQUIPMENT DESIGN

7 EQUIPMENT DESIGN
7.1 Waste Heat HX Design
Heat exchanger usually use to transfer heat from hot media to cold media, in these heat
exchanger usually there is no external heat and work interaction associated. Heat exchanger
are generally dived into two categories direct heat exchanger and indirect heat exchangers. In
direct heat exchanger there is direct contact of hot and cold media and they transfer heat
between them while in that of in-direct heat exchanger there is only heat exchange between
two media but there is no mixing between them. Direct heat exchanger are used when there is
no contamination issues while in-direct heat exchanger there is no contamination between two
media so generally used for process streams.[9] Heat exchanger include boilers, evaporators
and other shell and tube type heat exchanger.
7.1.1 Vaporizer type:
Generally there are two main types of vaporizer with respect to configuration. “Fire tube” and
“water tube” it depends on the configuration that where are you changing phase in shell side or
in tube side. Vaporizers types also define on operating pressure, vaporizers that operate on
pressure higher than 15psig are called as high pressure boiler. And those which operate under
15 psig are known as low or moderate pressure boilers.
Hot water boilers that have temperatures above 250° Fahrenheit or pressures higher than 160
psig are called ''high temperature hot water boilers''. Hot water boilers that have temperatures
not exceeding 250° Fahrenheit or pressures not exceeding 160 psig are called ''low temperature
hot water boiler. Vaporizers usually made up of different construction material i.e. cast iron,
iron, bronze or brass, it depends upon the material you are dealing with if it is corrosive will
use corrosion resistant material.
a. Vertical vaporizer
It is widely used for chlorine, ammonia, propane, methanol, sulfur dioxide, etc. Sizes range
from 50000 to 15000000 Btu/h (12,500 to 375000 Kcal/h).Very compact, high productivity,
easily combined with built in super heater with common control. Many heating media can be
used, including steam, hot water, and heat transfer fluids such as dowtherm, therminol, etc.
b. Indirect fluid heater
Very useful for high pressure or corrosive fluids where special metallurgy can be used in
smaller, less costly containment. Heating medium heats an intermediate bath of
water/NH3/Therminol or similar heat-transfer fluid that then heats a second coil at much lower
cost than shell side heating or boiling.[10] Combination of large flow rates liquid heat up and
subsequent boiling or super heating of mixed fluids with diverse boiling points. Needs special
stress analysis and mechanical design. Can preheat, boil, and super heat in small vessel.
c. Impedance electric heater
Electric heater for process fluids. Lowest cost heater for life of equipment. Easily cleanable,
very safe, very long life simple maintenance, good for high temperature boiling. Heat to
20000f, very useful for remote locations of corrosive fluids or gases. Electric current flows
though the containment tube and generates heat that is transferred to the fluid.

PRODUCTION OF ANILINE FROM PHENOL 41

 EQUIPMENT DESIGN

d. Cryogenic vaporizer
For boiling very low temperatures [-3270F (-2000C)]. Flare drums duty, to meet a few second
startup emergencies. Heating medium in shell and boiling fluids inside the tubes. Must be able
to copy with thermal expansion and adjustments in a few seconds without damaging stresses.
Avoid freeze-up problems and heat up the fluid to required exit temperatures with no
accompanying freeze up problems. Sizes can be up to 12 ft. in diameter and 40 ft. in length.
e. Kettle Type Vaporizer:
In kettle type boiler tube bundles are immersed in the poll of liquid and hot gases are in the
tubes this type of arrangement is very simple and easily available that why we are using this
configuration for our waste heat recovery unit.
f. Waste Heat Recovery Boiler:
Waste heat recovery unit is the unit which utilizes the waste heat of hot stream (which is to be
cooled for further processing) to heat the cold stream. We are using a kettle type boiler in order
to vaporize phenol at 16 bar pressure (316 oC) by using reactor outlet gases which is almost at
16 bar pressure and 438 oC. By using energy balance we came to know that after exchanging
heat with boiling phenol reactor outlet gases reduced to 349 0C.
g. Pump through Boiler:
Pump through boiler also known as forced convective boiler are used for low vaporization duty
in this type a pump is installed which help in recirculation but additional cost of pumping is
required. Therefor it is used where vaporization load is low and recirculation is feasible. The
circuit consists of a 1-2 exchanger serving as the vaporizer and a disengaging drum from which
the un-vaporized liquid is withdrawn and recombined with fresh feed. The generated vapor is
removed from the top of the drum.
h. Natural Circulation Vaporizer:
The vaporized may also be connected with a disengaging drum without the use of a
recirculating pump. This scheme is natural circulation. It requires that the disengaging drum be
elevated above the vaporizer. The advantages of forced circulation or natural circulation are in
part economics and a part dictated by space.
7.1.2 Selection: Which one is used & why?
The forced-circulation arrangement requires the use of a pump with its continuous operating
cost and fixed charges. As with forced-circulation evaporators, the rate of feed recirculation
can be controlled very closely. If the installation is small, then use of a pump preferable. If a
natural-circulation arrangement is used pump and stuffing box problems are eliminated but
considerably more headroom must be provided and recirculation rates cannot be controlled so
readily. [11]
7.1.3 Pinch Technology:
Pinch analysis, a technique for designing a process to minimize energy consumption and
maximize heat recovery, also known as heat integration, energy integration or pinch
technology. The technique calculates thermodynamically attainable energy targets for a given
process and identifies how to achieve them. A key insight is the pinch temperature, which is
the most constrained point in the process.
Vaporizer (boilers) are also classified as follow:

PRODUCTION OF ANILINE FROM PHENOL 42

 EQUIPMENT DESIGN

a. Pump through Boiler.

b. Thermosiphon Boiler.

PRODUCTION OF ANILINE FROM PHENOL 43

 EQUIPMENT DESIGN

Vaporizer type on the basis of configuration:

Table 19: Vaporizer Type

Type Size Cost Capacity Duty Maintenance Limitation

Fire Compact Inexpensive Low. 6E+5 to Easy Pressure up
Tube 5E+7 to 250 Pisa.
Relatively Take longer
Btu/hr
to build
pressure
Water Larger Expensive High Difficult Pressure up
tube to 5000
Instant
psig
pressure
build up

Table 20: Heat Exchanger Requirement

Properties Ammonia Phenol
Temperature [oC] 25-45.42 41-324
Cp [J/mol.K] 82.869 241.141

Hvap [J/mol] 18015.691 31338.370

Duty Required [kJ/hr] 949691.510 7216931.115

Flow Rate [kg/hr] 819.201 5127

PRODUCTION OF ANILINE FROM PHENOL 44

 EQUIPMENT DESIGN

7.1.4 Design Problem:

We have to Pre heat Phenol from 41 C to 315.8 oC and then vaporize it phenol at 315.8 oC. We
also have to cool the reactor outlet from 435 to 60 oC. Part of this heat is recovered by phenol
and temperature of out-let of reacted stream from waste heat recovery unit is 349 oC. [8]
Deigns steps:
a. Energy Balance.
b. Temperature Calculation (Tavg, LMTD).
c. Assume overall Heat transfer coefficient.
d. Area Calculation.
e. Number of Tubes Calculation.
Tube side and Shell side heat transfer coefficient calculation.
Overall Heat transfer coefficient calculation

PRODUCTION OF ANILINE FROM PHENOL 45

 EQUIPMENT DESIGN

7.1.5 Nomenclature of Waste Heat Recovery Unit:

qp Sensible Heat Load
qv Latent Heat Load
FT LMTD correction Factor
Tavg Bulk Tube Temperature
Tboiling Boiling Temperature of Phenol
do Outside Tube Dia
di Inside Tube Dia
Ar Area Required
NT Total Number of Tubes
A Area of a Tube
AT Total Area of Tubes
GT Mass Velocity
hi Inside Convective Heat Transfer Coefficient
hio Inside out Convective Heat Transfer Coefficient
Fl Liquid Level
Db Bundle Dia
ID Internal Shell Dia
Tw Wall temperature
hv Convective shell side Heat Transfer Coefficient Of latent Heat
hp Convective shell side Heat Transfer Coefficient Of Sensible Heat
hw Weighted Convective shell side Heat Transfer Coefficient
𝑈𝑐 Overall Clean Heat Transfer coefficient
Ud Overall Heat Transfer Coefficient
Rd Dirt Factor

PRODUCTION OF ANILINE FROM PHENOL 46

 EQUIPMENT DESIGN

LMTD Calculation:
(T1 − t2) − (T2 − t1)
LMTD =
(T1 − t2)
ln( )
(T2 − t1)
LMTD = 199
T1 − T2
R= = 0.3
t2 − t1

t2 − t1
S= = 0.7
T1 − t1
LMTD Correction Factor DQ Kern
FT = 0.88
LMTD Corrected = Ft × LMTD = 175℃
Tavg = 391℃
t boiling = 316

Tube specification:
Tube specs:
do = 31.75 mm
BWG=16
doi = 28.44 mm
Length = 1.21 m
= 4 ft

Figure 3: Tube Spec DQ Kern

PRODUCTION OF ANILINE FROM PHENOL 47

 EQUIPMENT DESIGN

Assuming Overall coefficient

Assume the value of Ud = 166 watt/m2 K
Total Q = 1.49E + 06 w
Area required
Q
Ar = = 51.3 m2
Ud ∆T
Surface area of a tube a = 0.121 m2
Number of tubes
Ar
NT = = 430
a
Tube side Calculation:
Inside flow area
= 6.4E − 04𝑚2
Total flow area
= AT = 0.136 m2
Mass velocity GT = mass flow/area
Mass flow = 6.6 kg/sec
GT = 6.6/0.136 = 48 kg/m2 sec
μ = 2.20E − 05 Pa. sec
GT di
Re = = 6.22E + 04
μ
Re. μ
Velocity = vt = = 8 m/sec
þ. di

PRODUCTION OF ANILINE FROM PHENOL 48

 EQUIPMENT DESIGN

Figure 4: Jh factor for ho DQ Kern

k μ. Cp 1 μ
hi = jH × ( ) × ( )3 × ( )0.14
di k μw
μ 0.14
( ) = 1.01
μW
Cp mean = 2617J/kg℃
K = 0.0523w/m℃
μ = 2.20E − 05 Pa. sec
μCp
= Pr = 1.1
k
hi = 303 watt/m2 ℃
hi di
hio =
do
hio = 272 watt/m2 ℃
Tube side Pressure Drop:
2
𝜇 −𝑚 𝜌𝑢𝑡
∆𝑃 = 𝑁𝑃 [8𝑗𝑓 (𝐿⁄𝑑 ) ( ⁄𝜇 ) + 2.5]
𝑖 2

PRODUCTION OF ANILINE FROM PHENOL 49

 EQUIPMENT DESIGN

Figure 5: Jf Factor for Pressure Drop Coulson Richardson

Re = 6.22E+04
5.98
∆P = 2 ∗ [8 ∗ 3E − 3 ∗ (42) × (1.01)0.14 + 2.5] × × (5.91)2
2
∆P = 136E + 03 N/m2
Shell Side Calculation:
Tube Bundle Dia:
𝑁𝑡 1⁄𝑛1
𝐷𝑏 = 𝑑𝑜( )
𝐾1
Pitch= PT = 1.25*do
NT = 430 , K1 = 0.156 , n1 = 2.291
Db = 1 m
Fluid Level dia = Fl = Db +.05 = 1.05 m Figure 6: Tube Bundle Dia Coulson Richardson

q = 2.85E + 04 W/m2
Internal shell ID = 1.8 × Db = 1.8 m

PRODUCTION OF ANILINE FROM PHENOL 50

 EQUIPMENT DESIGN

Wall Temperature:
hio
Tw = t b + (T − t b )
hio + ho avg
Tw = 340 ℃
Assume the weighted convective heat transfer coefficient:
h = 425 w/m2 ℃
t w – t b = 29.7 ℃ = 53.5℉

Figure 7: Convective Heat Transfer Coefficient DQ Kern

hv = 1703 watt/m2 ℃
hp = 329 watt/m2 ℃

hw = Q/(q v / hv + q p / hp ) = 448 watt/m2 ℃

hio ho
Uc =
hio + ho
Uc = 169 watt/m2 ℃
Ud = 162 watt/m2 ℃
Uc − U d
Rd = = 2.3E − 04
Uc ∗ U d
A – Areq
Over Design = =2%
Areq× 100

PRODUCTION OF ANILINE FROM PHENOL 51

 EQUIPMENT DESIGN

Vapors velocity:
Mass flow
uv =
vapor density × surface area
Mass flow = 1.42 kg/sec
Vapor density = 30.72 kg/m3
Surface area = width of liquid × length of shell = 2.18 m2
V = 2.12 m/sec
Shell Material- 18-8 Steel ( 18% chromium , 8 % nickel ) .08% carbon
Thickness of shell
f = 240 Mpa for 304
P = 5% increased of max Pressure = 2.40 Mpa
Tdesign = 10% increased of max T = 347 °C
J = 85 % if checked at only few points
Di = 1.81 m
PDi
ts =
2fJ − P
t s = 10.6 mm
Outer Dia of shell = ID + 2 × t s
= 1.83 m

PRODUCTION OF ANILINE FROM PHENOL 52

 EQUIPMENT DESIGN

7.1.6 Specification Sheet:

Table 21: WHRU Specification Sheet

HEAT EXCHANGER
Identification Item: Waste Heat Boiler Date: 12-May-2016
Item No.
No. Required By PTW
Function: To utilize the waste heat of Reactor outlet gases and produce saturated Phenol
vapors.
Operation: Continuous
Type: Horizontal
Split Ring Floating Head
Duty 1.49E+6 W Outside area 51.3 m2
Tube Side: Tubes:
Fluid Handled Reactor outlet Gas Inner Diameter 0.028 m
Flow Rate: 23671 kg/hr Outer Diameter 0.031 m
Pressure : 1.6 MPa Length 1.21 m
Temperature 435 to 348 ˚C No. Of Tubes 430
Passes 2
Tube Material 18-8 steel (304)
Shell Side: Shell:
Fluid Phenol Outer Diameter 1.8 m
Flow Rate 5127 kg/hr Passes 1
Temperature 41 to 316 ˚C Segmental Baffles
Pressure: 1.6 MPa No. Of Baffles Zero
Shell Material 18-8 steel (304)

Tolerances: Tubular Exchanger Manufacturer Standards (TEMA)

7.2 Furnace Design

Introduction:

PRODUCTION OF ANILINE FROM PHENOL 53

 EQUIPMENT DESIGN

Furnace or a fired heater is a high-temperature heating mean in which the chemical energy of
fuel is rehabilitated into heat which after that used to increase the temperature of material that
is called burden or stack which is placed within the furnace. A furnace that is operating at
temperature less than 1200⁰F (i.e.650⁰C) is usually called an oven. In ceramic industries,
furnaces are called kilns. In the CPI (Chemical Process Industries) and petrochemical
industries, furnaces can be termed as “kilns”, “burners”, “heaters”, incinerators or destructors.
Furnaces may be classified into over-all categories on the basis of efficiency and design.

Natural Draft Furnaces:

These furnaces are consisted of riveted-steel or cast-iron heat-exchangers built inside an
outside shell of masonry, brick or steel. Air circulation be governed by a large, upward pitched
pipes built of wood or metal, the pipes would station the hot air into ground or wall openings
inside the home. This technique for heating worked best because of the rise of warm air. [5]
Forced-Air Furnaces:
The 2nd category of housing furnace is atmospheric that is forced-air burner style with a cast-
iron or sectional steel or cast-iron heat-exchanger. This style of furnace is used to substitute the
highly natural draft systems, and that is occasionally installed on the current gravity channel
work. The heated air is then enthused by blowers which usually are belt-driven and intended
for an extensive variety of speeds. These furnaces still are big and large as compared to
current/modern furnaces, & have heavy steel outsides with bolt-on detachable panels. Energy
efficiency would range anyplace from just 50% to the rising of 65% AFUE. This style of
furnace still accommodates large, brick or masonry chimneys for flue gases and is then
eventually designed to accommodate air-conditioning schemes.

Forced draft Furnaces:

The 3rd category of furnace is the forced draft furnace which is a medium efficiency furnace
with steel heat exchanger and multi-speed blower. These furnaces were bodily much denser
than the preceding styles. They were fortified with combustion air-blowers that would pull air

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through the heat-exchanger which importantly increased fuel efficiency while letting the heat
exchangers to become compact. These furnaces have multi-speed blowers and were intended
to work with central air-conditioning systems.
Condensing Furnaces
The 4th category of furnace is the condensing or high-efficiency furnace. High-efficiency
furnaces can attain from 89% to maximum efficiency of 98%. This style of the furnace includes
a closed combustion part, combustion flow inducer and a subordinate heat exchanger. Because,
the heat-exchanger eradicates most of the hotness from the exhaust gases. It really condenses
water vapor and other substances (which form a slight acid) as it works. The outlet pipes are
usually installed with PVC tube against metal vent pipe to prevent corrosion. The draft inducer
allows for the surface piping to be directed steeply or horizontally as it exoduses the structure.
The well-organized preparation for the high-efficiency furnaces includes PVC piping that
carriages fresh combustion air after the outdoor of the homebased conventional to the furnace.
Generally, the combustion-air (i.e. Fresh air) PVC is directed together with the exhaust PVC
through installation and the pipes exit through a sidewall of the home in same location. High-
efficiency furnaces characteristically deliver a 25%-35% fuel funds over a 60% AFUE furnace.
7.2.1 Classification of Furnaces:
Furnaces are being categorized from different opinions of view in order to have an imprint of
representative types of frequent industrial furnaces which mainly comprises of three main
portions:
1. The 1st place where combustion will take place.
2. The working chamber or furnace correct where heat is shifted from yields of
combustion to the material under heating
3. The application for the removal of flue gases
Grouping is based on various factors are given below.
Based on the Heat Source:
1. Flame/combustion furnaces: These are the furnaces where the heat is developed due to
the combustion of fuels.
2. Thermo-electric furnaces: In these type of furnaces, heat is being generated by
electricity.
Based on type of fuel used:
a. Solid fuel fired furnaces
b. Liquid fuel fired furnaces
c. Gaseous fuel fired furnaces
d. Mixed/ multi fuel fired furnace
Based on charging system:
1. Manual charging furnace
2. Mechanical charging furnace
Based on mode of operation:

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a. Batch furnaces
b. Periodic furnaces
c. Continuous furnaces
Based on shape of furnace:
1. Crucible furnace
2. Shaft furnace
3. Hearth furnace
Based on the industries
1. Steel industry furnaces
2. Petroleum industry furnaces

7.2.2 Design and Operation:

A furnace or a direct fired heater is an equipment used to deliver heat for a process or can serve
a reactor which offers heat of reaction. Furnace design vary to as to its purpose, heating duty,
type of fuel and way of introducing combustion air. However, all of the furnaces have some
common features. Basically, fuel flows in to the burner and is burnt with the excess air provided
from an air blower. There can be more than one burner in a specific furnace which can be
organized in cells which heat a particular set of tubes. Burners can also be floor-mounted, wall
mounted or roof mounted depending upon the design. The flames heated up the tubes, which
at last heat the fluid inside in the first part of the furnace known as the radiant section. In the
chamber, where combustion takes place, is known as the firebox, the heat is transferred mostly
by radiation to tubes round the fire in the chamber. The heating fluid delivered through the
tubes and is thus heated to the preferred temperature. The gases taken from the combustion
known as the flue gases. After the flue gases leave the firebox, mostly furnace designs include
a convection section where more of the heat is mended before venting to the atmosphere
through the stack.[10]
Radiation Section:
It is a mode of heat transfer in which heat is transmitted by the electromagnetic waves. Here
heat is unconfined by combustion of fuel into an open space and transported by direct radiation
from flame and by the radiations reflects back from refractory walls padding the chamber. The
rate of heat transfer,
Q = f ∗ A ∗ (T14 – T24)
Where
Q = Heat flow by radiation alone to A(kJ/h)
T1 = Temperature of source (⁰C)
T2 = Temperature of sink (⁰C)
f = Dimensionless factor to allow for both geometry of the system and the non-black
emissivity’s of the hot and cold bodies.

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A = Effective heat transfer area of source or sink or cold body (m2)

Convection Section:
It is again a mode of heat transfer between one solid surface and the contiguous liquid or gas
that is in motion and it contains the combined effects of transmission and fluid motion. Here
the heat is recuperated from the flue gases by convection-mechanism. Combustion products
pass through the stack of tubes where heat transfer takes place by the following relation:
Qc = Uc ∗ A ∗ (LMTD)
Where,
Qc = Heat duty for convection section kJ/h
A = Heat transfer area of convection m2
LMTD = log mean temperature difference K
Uc = Convective heat transfer coefficient kJ/h.m2.K
Combustion:
Radiation in radiant section is rising due to the combustion of gaseous fuel. Combustion is the
procedure in which the chemical reaction of oxygen with the combustible share of the fuel
results in heart releases.
7.2.3 Selection Criteria:
The selection of a typical furnace is based upon the following points.
a. Kind of product to be heated
b. Firing temperature
c. Atmosphere of the flame
d. Kind of fuel that you use
e. Location and infrastructure
f. Condition of the load
g. Economics is usually the significant factor.

Selected Furnace:
The furnace which is selected for our required heat duty is box type furnace. The only
disadvantage of this furnace is the overheating of shield tubes but this difficulty is removed
when we design it for relatively large heat duty. It has been selected because economical tube
length versus heat duty graph shows that this furnace suits best at the given heat duty. As our
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desired furnace is of relatively small heat duty that is why box type furnace is the best suited
furnace fir this operation.

Furnace Design Methods:

The common methods of calculating heat absorptions in furnace are surveyed below.

Method of Lobo and Evans:

This method makes the use of the overall exchange factor “f”’ and a Stephen-Boltzmann Law
type equation. It has a decent theoretical basis and is used lengthily in refinery-furnace design
work. It is also suggested for oil- or gas fired boilers. The average deviation between the
foretold and experiential heat absorption for 85 tests on nineteen different refinery furnaces
fluctuating widely in physical and operating characteristics was 5.3%. The maximum deviance
was 16%.

Method of Wilson, Lobo and Hottel:

This is an empirical technique which can be used for box type furnaces fired with oil or refinery
gas when flux lie between 5000 and 30,000 Btu/ (h) (ft2) of circumferential tube superficial.
Other restrictions are that tube-surface temperature be at least 400⁰F lesser than the radiant-
section exit gas temperature. The mean beam length should not be fewer than 15 ft. This method
is extensively used in industry and is endorsed under the above boundaries when the precision
of the Lobo-Evans equation is not required. For utmost tests mentioned to under the Lobo-
Evans method, the normal deviation was 6% and the maximum deviation 33%.

The Orrok-Hudson Equation:

This is a premature empirical equation for calculating heat of absorption in the radiant section
of a water-tube boiler. It has been substituted by more accurate terminologies and is of
incomplete value for design work. It can be used to guess the effects of variations in firing rate
or air-fuel ratio for a current boiler fired with coal or oil if it is recognized that there will be no
considerable change in either the character or level of the slagging of the furnace tubes. In such
applications, it may be necessary to regulate the constant in the equation to outfit the known
operating conditions.

Wohlenberg Simplified Method:

This is also an empirical method, though certainly much sounder than the Orrok-Hudson
equation for scheming radiant-heat absorption. It is useful only for coal firing. It is yet again
repeated that a knowledge of the predicted slagging is a pre-requisite to the solicitation of a
heat transfer equation to a boiler. Tests on 7 large boilers indicated an avg. deviation of about
10 percent when the slag factor was estimated from the furnace appearance. The maximum
deviation was about 50% for stoker firing, but improved accuracy was obtained in furnaces
fired with pulverized coal.
To design the furnace beneath consideration is “Lobo and Evans” method on the basis of
simplicity in its calculations and its industrial applications, has been followed.
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Calculation of Exchange factor:

Exchange factor depends mainly on the emissivity of the source. Source can be combustion
gases, usually CO2, H2O, CO, N2, H2, SO2. There is a great alteration of emissivity of these
gases. Diatomic gases such as N2, H2 has precisely less emissivity. So they are deserted in
calculation. Furnaces are functioned with sufficient excess air to eradicate CO. Small quantity
of sulfur in the fuel is deserted. Therefore, we only consider the emissivity of H2O and CO2.
Instead of composition of CO2 and H2O we acquire partial pressure of CO2 and H2O from
graph, where it is schemed against % excess air. So to find the exchange factor we need
concentration of CO2 and H2O which is gotten by partial pressure of both gases and flame
length. [2][12]

Stephen Boltzmann Law:

Stephen Boltzmann stated that total radiations from a perfect black body is proportional to the
fourth power of the absolute temperature of the body
ɛ α T4
ɛ = σ T4

Where, σ = 0.173 * 10 8 Btu / h.ft2 ⁰F

So, equation becomes

Q / A = 0.173 * 108 T4 -----Same amount of heat is absorbed by another black body.

7.2.4 Furnace Design:

Design Steps of Radiant Section

1. Assume 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐹𝑙𝑢𝑥

2. Calculate factor ∑𝑄/𝛼𝐴𝐶𝑃 = 2 × 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐹𝑙𝑢𝑥

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3. Calculate ∑𝑄/𝛼𝐴𝐶𝑃 𝑓 for 𝑓 = 0.57

4. Calculate 𝑇𝑆 , tube surface temperature

5. Estimate 𝑇𝐺 , using ∑𝑄/𝛼𝐴𝐶𝑃 𝑓 and 𝑇𝑆

6. Calculate number of tubes
7. Set dimensions
8. Calculate volume and mean beam length

9. Calculate cold plane area 𝐴𝐶𝑃

10. Calculate absorptivity 𝛼 and 𝛼𝐴𝐶𝑃

11. Calculate total exposed area 𝐴𝑇

12. Calculate effective refractory area 𝐴𝑅 = 𝐴𝑇 − 𝛼𝐴𝐶𝑃

13. Calculate gas emissivity Ɛ and overall exchange factor 𝑓

14. Calculate ∑𝑄 from heat balance

15. Recalculate ∑𝑄/𝛼𝐴𝐶𝑃 𝑓 and corresponding 𝑇𝐺

16. Iterate to converge the value of 𝑇𝐺 in step 5 and 15 [13]

Overall Heat Balance:

∑Q = 𝑄𝑓𝑢𝑒𝑙 + 𝑄𝑎𝑖𝑟 –𝑄𝑒𝑥ℎ𝑎𝑢𝑠𝑡 – 𝑄𝑤𝑎𝑙𝑙

Assumed average flux = 193909.4016 KJ/hr.m2

Radiant section efficiency = 70 % Qrequired from energy balance: 16735143.28 KJ/hr

QRadiant = 0.7 (QRequired ) = 0.7 ∗ 16735143.28 = 11714600.3 KJ/hr

As a standard, tube dimensions will be:

Internal diameter (I.D) = 0.102 m
Outer diameter (O.D) = 0.114 m
Radius (r) = 0.057 m

Center to center spacing (ctc) = 2 ∗ nominal pipe size = 2 ∗ 0.114 = 0.228 m

Most economical tube length = 6.7 m

Tube area = πDL = 3.14 ∗ 0.114 ∗ 6.7 = 2.398

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Flux per tube= 465059.123 KJ/hr

No. of tubes in radiant section (N) = Qradiant /flux per tube = 42.69 = 46 tubes.
Tubes along the wall = 25
Tubes along the ceiling = 13
Tubes along the shield section = 8
Length of radiant section (LR) = (tubes along wall*tube dia) + (tube spacing*ctc) = 8.32 m
Height of radiant section (HR) = (tubes along ceiling*tube dia) + (tube spacing*ctc)=5.1 m
Width of radian section (WR) = (tubes along shield section*Do) + (tube spacing*ctc) = 3.4m

Volume of radiant section = 125 m3

End wall area = 2 ∗ W ∗ H = 34.68 m2

Side wall area = 2 ∗ L ∗ H = 73.44 m2

Roof + Floor area = 2 ∗ W ∗ H = 48.96 m2

Total exposed area (At) = 177 m2

Mean beam length (I) = 2/3 (radiant section volume)1/3 = 3.3 m

Cold plane area (Acp) = (ctc)(tube length)(No. of tubes) = 70.2 m2

𝐑𝐞𝐟𝐫𝐚𝐜𝐭𝐨𝐫𝐲 𝐚𝐫𝐞𝐚 𝐀𝐫 = 𝟑𝟐. 𝟐 𝐦2

Partial pressure of CO2 & H2O (P) = 0.2288 – 0.229 x + 0.09 x2 = 31.72 Kpa

X = fraction excess air = 20 %

PI = 31.728 ∗ 3.3 = 104.7 Kpa. m = 3.38 atm. ft

a = 0.47916 – 0.19847 (Z) + 0.022569(Z)2 = 0.17796
b = 0.047029 + 0.0669(Z) − 0.01528(Z)2 = 0.1252
c = 0.000803 − 0.00726(Z) + 0.001597(Z)2 = −0.007228
Where Z = Tg + 460/1000

Emissivity (ɛ) = a + b (PI) + c(PI)2 = 0.51

Overall exchange factor (f) = 0.61

𝐀𝐜𝐭𝐮𝐚𝐥 𝐟𝐥𝐮𝐱 = 𝟏𝟕𝟒𝟎𝟗𝟕. 𝟎𝟖 𝐊𝐉/𝐡𝐫. 𝐦2

Design of Convection section

Design steps for the convection section are as follows;

1. Calculate convection section heat duty

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2. Calculate 𝑇𝑔𝑎𝑠 at outlet of convection section

3. Calculate 𝐿𝑀𝑇𝐷
4. Calculate overall convective heat transfer coefficient 𝑈𝑐
5. Calculate convective heat transfer area 𝐴𝑐
6. Calculate number of tubes
7. Find dimensions of convection section
8. Calculate volume

𝑄𝐶𝑜𝑛𝑣𝑒𝑐𝑡𝑖𝑜𝑣 = 𝑄𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 – 𝑄𝑅𝑎𝑑𝑖𝑎𝑛𝑡 = 5020542.984 kJ/hr

Net heat contained by flue gases = 1 – (70% radiation + 2 % wall) = 0.28 = 28 %

Gas temperature (Tgas) = 899 ⁰C

(∆T1 - ∆T2)/ln(∆T2/∆T1)
∆T1 = 590 ⁰C
For counter flow, ∆T2 = 21 ⁰C
LMTD = 170 ⁰C

Average temperature = (Tin + Tcross) / 2 = 535 ⁰C

Mean gas film temperature = Tf = Tcrude,avg + LMTD / 2 = 607 ⁰C

Tube dimensions; same as the radiant section:

Outer diameter (O. D) = 0.114m

centre to centre distance = (ctc) = 0.228 m

Gross width = (Nshield + 0.5) ∗ ctc = 2.052 m

Free width = Gross width – (Nshield∗ O. D) = 1.871 m

𝐀𝐫𝐞𝐚 = 𝐅𝐫𝐞𝐞 𝐰𝐢𝐝𝐭𝐡 ∗ 𝐓𝐮𝐛𝐞 𝐥𝐞𝐧𝐠𝐭𝐡 = 𝟏𝟐. 𝟓 𝐦2

For 20 % excess air

Total flue gases = 975lb/MMBtu = 420.0775 kg/MMkJ

Mass flow rate of gases = Total flue gasees ∗ QF = 2.7 kg/s

Mass velocity of gases = Mass flow rate / Area = 0.2249 kg/m2. sec

Overall heat transfer coefficient, Uc = (a + bG + cG2) (4.5/O. D) 0.25 =

53.106 kJ/s. m2. ⁰C

Surface area required (A) = QC /Uc. LMTD = 651 m2

No. of tubes for convection section = Area/πL(O. D) = 160 tubes

Nt(shield)= 8

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Number of rows = 20
Height (HC) = (No. of rows + 1) ctc = 4.7 m

Length (LC) = 7.2 m

Width (WC) = (Nshield + 1) = 2.052 m

Volume of convection section (VC) = 70.7 m3

𝐕𝐨𝐥𝐮𝐦𝐞 𝐨𝐟 𝐟𝐮𝐫𝐧𝐚𝐜𝐞 = 𝐕R + 𝐕C = 𝟐𝟒𝟐 𝐦3

Furnace Specification Sheet

Equipment Name Furnace

Operation Continuous
Total required heat duty 16735143.28 kJ/h
Fuel required 507.145kg/hr
Heat flux 174097.08 kJ/h.m2
Radiant Heat, QR 19854292.32 kJ/h
I.D of tube 0.102 m
O.D of tube 0.114 m
Center to center distance 0.228m
Tube length 6.7 m
No. of tubes in radiant section 46
Volume of radiant section 125 m3
Convection section heat 5020542.984 kJ/hr
No. of tubes In convection section 144
Volume of convection section 59.55 m3
Stack inlet temperature 83⁰C
Stack outlet temperature 45 ⁰C
Total volume of furnace 229.86m3
Material of construction 50Cr 50Ni
Refractory Material Fire bricks

7.3 Reactor Design

7.3.1 Types of reactors:

The following features are generally used to categorize reactor designs:

1. Mode of process: batch or continuous.

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2. Number of phases present: heterogeneous or homogeneous

3. Geometry of reactor: manner of phase contacting and flow Pattern.

General example reactors:

 Continuous stirred tank reactor (CSTR).

 Tubular reactor
 Packed bed reactor (fixed and moving)
 Fluidized bed reactor
Batch or continuous processing:
In a batch processes all the components are added at the beginning; then the reaction takes
place and proceeds with time and the composition of the reagents change with time after
specific reaction time reactants are converted into the products reaction is stopped and the
product is taken out of the reaction vessel. Batch processes are usually favorable for the small
scale production unit or where reaction time is very high and they are abundantly used in the
industries like food industry, wine fermentation, and pigments and in polymer industry.[14]
In continuous process the reactants taking part in the reaction are fed to the reactor and the
product is taken out continuously. These reactors operate under steady state conditions. It has
different advantages over batch process. In continuous process as the product is produced
continuously which reduce the overall production cost and there is flexibility in these processes
usually continuous mode of operation is selected where large-scale production is required.
There is another class of process which includes both continuous and batch operation.
Heterogeneous and homogeneous reactions:
Homogeneous reactions are those reactions in which reactants, products and catalyst used are
in same phase. Phases may be are gaseous or liquid solids are not taken in to account for
homogeneous reactions. Gas phase reactions are always operated continuously on the other
hand liquid phase reactions can be operated continuously or batch.
For gas phase reactions tubular reactors are used for liquid phase fixed bed reactors or cracking
column can be used.

Continuous stirred tank reactor:

CSTR is considered as the basic chemical reactor. CSTR is operated on continuous mode. Feed
is continuously added and product is drawn out. CSTR is usually tank with the stirrer. Size of
the reactor varies from few liters to thousands of liters. They are used for both homogeneous
and heterogeneous reactions these reactors are preferred where efficient mass and heat transfer
is required.

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7.3.2 Selection criteria of reactor:

There are different factors that need to be taken into account for selection of reactor. Selected
reactor must fulfill our requirements and produce desired quality of product.[15]

Following are the major factors:

 Conversion
 Selectivity
 Productivity
 Safety
 Economics
 Availability
 Flexibility
 Compatibility with processing
 Energy utilization
 Feasibility
 Investment
 Operating cost
 Heat exchange and mixing

7.3.3 Selected reactor

 We have selected fixed bed reactor because of the following characteristics.
 Effective at high temperatures and pressures
 Low cost of construction, operation and maintenance
 No entrainment of particles as in fluidized bed reactor
 Small residence time
 Low investment
 Low operating cost

Advantages:
These reactors are preferred over other reactors because of following reasons:
 Easy to construct, maintenance and operation of fixed bed reactor is easy relative to
moving bed or fluidized bed.
 Minimum requirement for Auxiliary equipment.
 There is no requirement to remove catalyst from the product stream as it is already
separated

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 These rectors are flexible they can be operated in wide range of space times.
 Product formation is high due to increased contact of catalyst and reactants

Packed bed:
Packed bed is a hollow tube filled with the packing, the purpose of packing is to increase the
contact of the phases, and packed bed can be used in different equipment in the industry like
chemical reactions, distillation columns and in scrubbers. Packed beds can also be used to store
heat energy in chemical industry. Hot gases are passed through the bed which heats up the
packing inside the bed; in order to recover heat from the bed cold stream which needs to be
heated up is passed through it. Mostly preheating of air is done by using this technique.
Packed bed reactor
Packed bed reactors:

In process industry backed bed reactor is vessel or hollow tube filled with the solid catalyst
packing. Catalyst packing may be of different type it can be a randomly filled catalyst packing
or it can be structured packing. These reactors are suitable for liquid and gas phase reaction.
Catalyst packing is added to increase the contact of the reactants and to reduce the activation
energy of the reaction. Packed beds may contain granular activated carbon, zeolites in our case
the alumina silica catalyst is used.
Packed bed reactors are also known as fixed bed reactor and these reactors are mostly used for
the catalytic reactions. Most of the reactors have vertical orientation with immobilized bed
containing catalyst. Fixed bed reactors are heterogeneous reaction systems, If the feed is liquid
than reactants flow by gravity.
Basic operation:

Feed enters either from bottom or top it depends on the feed condition if it is in liquid state
feed enters from top if it is gaseous form. Feed flow through the bed an come in contact with
the catalyst and as a result reactants react to form products. During the design of the reactor
following are the things that needs to be taken into account. One of the main thing is active life
of catalyst because this will affect the length of time a bed of catalyst may be used and thus
how long the reactor may be run before the catalyst needs to be regenerated.[16]

7.3.4 Reactor design:

Assumptions
 Steady State Flow
 One Dimensional Flow
 Plug Flow
 Distribution of Concentration, Heat, Pressure and Temperature is uniform in each cross
section of the Reactor
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 Adiabatic Operation (No Heat Losses)

 No Side reaction is occurring in the system

7.3.5 Design Steps:

 Calculate the mass of catalyst required for the optimum conversion
 Calculate the Superficial Gas Velocity
 Calculate the bed area
 Calculate the Bed Diameter and Round off D in 6 inches increments. If D is less than
30 inches use Standard Pipe
 After rounding D, calculate the actual bed area
 Calculate the Actual Superficial Velocity
 Calculate the actual bed pressure drop for a unit length
 Calculate the actual pressure drop per unit length
 Calculate the Bed Length. Calculate Minimum and Maximum and adjust length if
necessary.
 Calculate the Reactor Length. Round off Length of Reactor 3 inches increments.
 Calculate the Total Pressure Drop
 Calculate the Actual Bed Volume
 Calculate the Catalyst Mass from the Actual Bed Volume
 Calculate the Reactor Volume

7.3.6 Reaction kinetics:

Main reaction in our process is phenol and ammonia reaction. One mole of ammonia and one
mole of phenol react and form 1 mole of aniline and 1 mole of water. Ammonia to phenol ratio
is (20:1). Ammonia is in excess which helps to increase the selectivity of the aniline. Order of
reaction is pseudo first order reaction because ammonia is in excess and limiting reaction is
phenol. [17]

Nomenclature:

VB Volume of Bed

Vv Volumetric Flow Rate

Scv Space Velocity
vs Superficial Velocity

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AB Area of Bed
DR Reactor Diameter
LB Length of Bed
LR Reactor Length
Δp Pressure Drop
ρ Density Of catalyst
W Mass Of catalyst
Φ Porosity
µ Viscosity
LI Inert Length

Weight of Bed:
Weight of bed is calculated by integrating design equation according to given conditions

dx −ra
=
dw Fao
Fractional Conversion= x = 0.97

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Weight of catalyst comes out to be = WB = 900 kg

Design equation is solved on polymath and the result is 900 kg.

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Catalyst Wieght vs Conversion

1.2

0.8
Conversion

0.6

0.4

0.2

0
0 200 400 600 800 1000 1200 1400 1600
Wieght of Catalyst

Volume of the bed:

Volume of bed is calculated by dividing weight of catalyst divided by density of the catalyst.

W
VB =
ρ
Wight of Catalyst = W = 900 kg
Bulk density = ρ = 1300 kg/m3
900
VB =
1300

Volume of bed = VB = 0.7 m3

PRODUCTION OF ANILINE FROM PHENOL 70

 EQUIPMENT DESIGN

Length and Diameter:

Assumption
L
=3
D
Then using Volume expression,
π 2
V= D L
4
Volume of Bed= VB = 0.7 m3
Diameter = D = 0.66 m
Length of the bed= LB= 2 m

Corrected length and diameter:

Diameter of the vessel must be of multiple of 6 (in) in order to compensate availability in the
market.

Diameter= D = 0.76 m (30 in)

Length= LB = 2.3 m

Corrected volume:
𝝅 𝟐
𝑽= 𝑥𝑫 𝑳
𝟒
Diameter = D = 0.76m
Length of the Bed = 2.3m
Volume of the bed = VB = 1.05 m3

Area of Bed:
𝜋 2
𝐴𝐵 = 𝐷
4
Diameter = D = 0.76m
Area of Bed = AB = 0.46m2

PRODUCTION OF ANILINE FROM PHENOL 71

 EQUIPMENT DESIGN

Length of the reactor:

LR = L B + LI
Length of bed= LB = 2.3m
Incremental length= LI = 0.91 m (3 ft.)
Length of the reactor= LR =3.1m

Volume of reactor:
𝜋 2
𝑉𝑅 = 𝐷 𝐿𝑅
4
Length of the reactor= LR =3.1m
Diameter = D= 0.76m
Volume of the reactor = VR = 1.5 m3

Volumetric Flow rate:

Feed is in gaseous form, Assume ideal conditions

P VV = mT R T

Molar Flow rate in feed= mT =318.1649 mole/sec

Volumetric flow rate= VV = 1.1540m3/sec

Superficial velocity:

Vv = AB vs
Volumetric flow rate= VV = 1.1540m3/sec
Area of Bed = AB = 0.46m2
Superficial velocity = vs = 2.5 m/sec

Pressure Drop:
Ergun Equation

μvs (1 − ε)2 (vs )2 1 − ε

(∆p)B = 150 [ 2] + 1.75 [ρ ]
(Dp ) (ε)3 Dp (ε)3

Average density= ρ= 5.7 kg/m3

Void fraction= ε = 0.255

PRODUCTION OF ANILINE FROM PHENOL 72

 EQUIPMENT DESIGN

Diameter= Dp = 0.005m

Pressure Drop per meter =(∆p)B = 12000 pa/m (12kpa/m)

Total pressure Drop:

∆𝑝 = (∆𝑝)𝐵 (𝐿𝑅)

Length of the reactor= LR =3.1m

Pressure Drop per meter =(∆p)B = 12000 pa/m (12kpa/m)

Total pressure drop = ∆p = 37000 pa (37kpa)

PRODUCTION OF ANILINE FROM PHENOL 73

 EQUIPMENT DESIGN

7.4 Stripper Design

7.4.1 Problem Statement

It is required to strip out 99% of the un-reacted ammonia from the product using Reboiled
Stripper. Recycle back this ammonia to the main reactor.
7.4.2 Nomenclature
Aa Active area of plate
Aap Clearance area under apron
Ac Total Column cross-sectional area
Ad Downcomer cross-sectional area
Ah Total Hole are
Ap Perforated area
Co Orifice coefficient
Dc Column diameter
dh Hole diameter
Eo Column efficiency
hap Apron clearance
hb Height of liquid back-up in terms of clear liquid head
hdc Downcomer back up in clear liquid form
hd Dry plate pressure drop
how Height of liquid crest over downcomer
hr Plate residual pressure drop
ht Total plate pressure drop
hw Weir height
Kk K-value of key component
mv Vapor mass flowrate
mL Liquid mass flowrate
Lwd Liquid mass flowrate through downcomer
Se Stripping factor
V Vapor flowrate
L Liquid flowrate

PRODUCTION OF ANILINE FROM PHENOL 74

 EQUIPMENT DESIGN

7.4.3 Design Steps

 Calculation of Stripping Factor

 Calculation of N And N(actual)
 Calculation of Flooding velocity (vv) and actual velocity (vs)
 Calculation for Diameter (D)
 Calculation for Pressure drop
 Calculation of Height of Column
 Calculation for Down comers area, active area, hole area, hole dia, weir height
 Calculation for Weeping rate
 Calculation for Downcomer Back-up
 Calculation for Perforated Area
 Number of holes

Selection of Tray Column over Packed Column

Assume Velocity = 0.609 m/s

ṁ
Volumetric flowrate = = 0.753 m3/s
ρ
Vol. flowrate
Area = = 1.24 m2
velocity
Column Diameter = 1.26 m; 4.12 ft
As D > 2.5 ft; tray column is preferred over packed column
7.4.4 Selection of Tray Type
Sieve Trays Valve Trays Bubble Cap Trays
Pressure Drop Lowest Highest Moderate
Cost Low 20% more that Sieve tray Most expensive
Efficiency High High Moderate
Fouling Tendency Lowest Low to Moderate Highest
Capacity Highest High to very High Moderate

Calculation for Ideal & Actual no. of Stages

Kremsor Equation
V = 17588 kg/hr
L = 23710 kg/hr
KkV
Se = = 1.51
L

PRODUCTION OF ANILINE FROM PHENOL 75

 EQUIPMENT DESIGN

Se − 1
φs =
Se N+1 − 1
Ideal no. of stages = N = 9
φs = 0.01
K-value of key component= Kk = 2.04
Column Efficiency

Eo = 19.2 − 57.8 logμL = 0.58

Actual # of Stages: NA = 16

Calculation for Diameter

Tray Spacing = Zt = 0.457 m
mL ρv 0.5
Flooding Factor = k = [ ( ) ∗ Zt ] = 0.052
mv ρL
σ 0.2
Entrainment Factor = k v = 0.9 k ( ) = 0.041
20
Surface Tension; σ (dyne/cm)
ρL − ρv 0.5
Flooding velocity = vv = k v [ ] = 0.40 m/s
ρv

Actual velocity = vs = 0.9 vv = 0.36 m/s

ρ
Column Area = ( ) = 2.095 m2
vs

Column Diameter = 1.63 m

Calculation for Height & Pressure drop
ρ
Column Area = ( ) = 2.095 m2
vs

Column Diameter = 1.63 m

H = NA ∗ Zt + 3 [ft] + 0.25 ∗ D + Ls

Column Height = 11.59 m

Pressure drop per tray = 0.05 psi
Total pressure drop column = 0.054 Bar
Top Pressure = 13 Bar
Bottom Pressure = 13.054 Bar

PRODUCTION OF ANILINE FROM PHENOL 76

 EQUIPMENT DESIGN

Plate design
Column Diameter = Dc = 1.63 m
Column Area = Ac =2.087 m2
Down comer Area = Ad = 0.250 m2 (12 percent of column area)
Net Area = An = Ac – Ad = 1.836 m2
Active Area = Aa = Ac – 2Ad = 1.586 m2
Hole Area = Ah = 0.159 m2 (10 percent of Active Area)
Weir Length = lw = 1.255 m
Hole Diameter = dh = 5 mm
Plate thickness = 5 mm
Weir Height = hw = 50 mm
Hole Pitch = 2.5 mm
Calculation for Weeping Rate
Max. Liquid Rate = L𝑤𝑑 = 6.58 kg/s
Min. Liquid Rate = 4.61 kg/s (70 percent of max. liquid rate)
2
𝐿 3
ℎ𝑤 = 750 ∗ [𝜌𝐿𝑤𝑑 ]
𝑙𝑤

how = 25.56 mm
how = 20.16 mm
K2= 30.5 (From graph11.30)
[𝐾2 −0.9(25.4−𝑑ℎ )]
𝑢̌ = = 2.42 𝑚/𝑠
𝜌𝑣 0.5

𝑚𝑖𝑛𝑖𝑚𝑢𝑚 𝑣𝑎𝑝𝑜𝑟 𝑟𝑎𝑡𝑒

𝑀𝑖𝑛. 𝑣𝑎𝑝𝑜𝑟 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 = = 3.325 𝑚/𝑠
𝐴ℎ

So minimum operating rate is well above weeping point [18]

Downcomer Liquid back-up

hap = hw – 10 = 40 mm
Aap = 0.024 m2
As this is less than Ad, use Aap in equation
Lwd 2
hdc=166* [ρ A ] = 18
L m

PRODUCTION OF ANILINE FROM PHENOL 77

 EQUIPMENT DESIGN

Back-up in Downcomer

ℎ𝑡 = ℎ𝑑 + ℎ𝑤 + ℎ𝑜𝑤 + ℎ𝑟 = 0.131 𝑚

hb=(hw+how)+ht+hdc=225 mm=0.225 m
Perforated Area
Lw/Dc = 0.77 (from Figure 11.32)
𝜃𝑐 = 100°
angle subtended at plate edge by unperforated strip = 80o
Area of unperforated edge strip = 0.11 m2
Mean length of calming zone = 1.556 m
Area of calming zone = 2*(lc *0.05) = 0.156 m2
Total Area of perforations = Ap = 1.32 m2
Area of one hole = 1.96e-5
Number of holes = 4076

PRODUCTION OF ANILINE FROM PHENOL 78

 EQUIPMENT DESIGN

COLUMN SPECIFICATION SHEET

PROJECT TITLE: PRODUCTION OF Date: Compiled by: 2012-CH-69

ANILINE 8/5/2016 Checked by:
Item # SKETCH
Item Reboiled Stripper
Description
Column
Diameter (m) 1.63
Hole Diameter (m) 0.005
Tray Spacing (m) 0.46
Number of Trays 16
Height (m) 11.59
Weir Height (m) 0.05
Tray Type Sieve Tray
Number of Holes 8076
Column Pressure Drop 5.472
(KPa)
Material of Construction Carbon Steel
Fluid:
Phase (V,L,V/L) V/L
Liquid Temperature (oC) 38
Bottom Temperature (oC) 191
Weeping Velocity (m/s) 2.416
Vapor Velocity (m/s) 3.325
Down comer liquid back- 0.225
up (m)

PRODUCTION OF ANILINE FROM PHENOL 79

 EQUIPMENT DESIGN

7.5 Aniline Column Design

Operating Range of Distillation Column
a. Flow rate, composition, temperature, phase condition of feed
b. Column pressure
c. Degree of sub-cooling in condenser
d. Reflux Ratio R=L/D
e. Vapor rate given by heat input to reboiler
f. Amount of product taken at the bottom or top
7.5.1 Choice of Column
There are two choices for distillation column.
a. Packed column
b. Tray column
Operations in these two types are fairly dissimilar. The following factors are considered:
a. Factors that dependent on the system are foaming, scale, corrosive systems, fouling
factors, pressure drop, heat evolution and liquid holdup.
b. Factors that reliant on on the fluid flow moment.
c. Factors that be contingent upon the physical features of the column and its internals
i.e. weight, side stream, maintenance, size and cost.
d. Factors that be subject to upon mode of operation i.e. continuous distillation, batch
distillation, discontinuous distillation, and turn down.
7.5.2 Merits of Tray Column
The comparative qualities of plate over packed column are as follows:
a. Plate column are designed to handle extensive series of liquid flow rates.
b. If a system comprises solid subjects, plate column will be preferred, because solid will
fill in the spaces.
c. When flow rate of liquid are low as compared to gases dispersion problems are deal in
plate column
d. Weight of the packed column is more as compared to plate column for large column
heights.
e. Man holes will be allowed for cleaning in tray column but in packed columns packing
must be removed before cleaning.
f. When there is a non-foaming systems the plate column is chosen.
g. Design and data availability of plate column is easy as compared to packed column.
h. Inter-stage cooler are used to remove heat of solution or reaction in plate column.
i. For larger temperature changes tray column are always preferred.
j. Generally packed column are not preferred for diameter larger than 0.67m and tray
column diameter is rarely less than 0.67m.[15]

PRODUCTION OF ANILINE FROM PHENOL 80

 EQUIPMENT DESIGN

7.5.3 Types of Tray

Generally the types of trays which are used
a. Sieve Tray
b. Bubble Cap Tray
c. Valve Tray
Choice of Tray
We have choose sieve tray due to:
a. They are light weight and low cost. Install is easy and cheap.
b. Low pressure drop in comparison to bubble cap trays.
c. Top efficiency is normally high.
d. Maintenance cost is compact due to the simplicity of cleaning.
e. Flexibility of operation.
7.5.4 Designing Steps of Distillation Column
a. Calculation Of Nmin
b. Calculation Of Rmin And R
c. Calculation Of N And N(actual)
d. Calculation Of 𝑁𝑆 And 𝑁𝑅
e. Calculation Of Column Diameter
f. Calculation For The Plate Design
g. Calculation For The Weeping Check
h. Calculation For The Plate Pressure Drop
i. Calculation For The Down-comer Residence Time Check
j. Calculation For The Entrainment Check
k. Calculation For The Perforated Area
l. Calculation For The Number Of Holes
m. Calculation For Column Height

PRODUCTION OF ANILINE FROM PHENOL 81

 EQUIPMENT DESIGN

7.5.5 Nomenclature:
Aa Active area of plate
Aap Clearance area under apron
Ac Total Column cross-sectional area
Ad Downcomer cross-sectional area
Ah Total Hole are
Ap Perforated area
Co Orifice coefficient
Dc Column diameter
dh Hole diameter
Eo Column efficiency
hap Apron clearance
hb Height of liquid back-up in terms of clear liquid head
hdc Downcomer back up in clear liquid form
hd Dry plate pressure drop
how Height of liquid crest over downcomer
hr Plate residual pressure drop
ht Total plate pressure drop
hw Weir height
mv Vapor mass flowrate
mL Liquid mass flowrate
Lwd Liquid mass flowrate through downcomer
V Vapor flowrate
L Liquid flowrate

PRODUCTION OF ANILINE FROM PHENOL 82

 EQUIPMENT DESIGN

7.5.6 Design of Aniline Recovery Column

Column Conditions:
• Feed = 4994 kg/h
• Feed Temperature = 185.37°C
• Top Temperature = 183.84°C
• Bottom Temperature = 231°C
• Top Pressure = 1 bar
• Bottom Pressure = 1.16 bar

No. of ideal plates:

• Phenol = LNK

• Aniline = LK 𝒙𝐴,𝐷 = 0.965

• Diphenylamine = HK 𝒙𝐵,𝑊 = 0.400

Fenske Equation
𝒙𝐴,𝐷 𝒙𝐵,𝑊
𝑳𝒐𝒈( ∗ )
𝒙𝐵,𝐷 𝒙
𝐴, 𝑊
𝑵𝒎𝒊𝒏 = 𝑳𝒐𝒈(α𝟏𝟑 (av))

Nmin = 3
𝟏 𝑿𝑫𝒍 𝒙𝑫𝒉𝒌
Rmin = ( − 𝛼 )
𝜶−𝟏 𝒙𝒍 𝒙𝒉𝒌

Rmin = 0.061 R = 1.4*Rmin R = 0.084

Stage calculations
𝑁𝑖𝑑𝑒𝑎𝑙 = 10
O’ Connel Relation for Column Efficiency ƍL(mix) ,top = 869.9
3
kg/m
E= 51-32.5Log (µ (av) α12 (av)) E = 69% ƍL(mix),bottom = 906.6
3
kg/m
3
Nactual = 10/0.69 = 14 ƍv(mix),top = 2.48 kg/m
3
NR = 10 NS = 4 q = 1(feed is sat. liquid) ƍv(mix),bottom = 3.4 kg/m

(Rmin+1)D = Vmin Vmin = 4213 kg/h D = 4174 kg/h

PRODUCTION OF ANILINE FROM PHENOL 83

 EQUIPMENT DESIGN

Table 22: Physical Properties at top & bottom

Physical Property Symbol At the bottom of the At the top of the

column column
Liquid Flow Rate Lm 55.21 kgmol/h 3.76 kgmol/h
Vapour Flow Rate Vm 48.61 kgmol/h 48.61 kgmol/h
Vapour Density ρv 3.40 kg/m3 2.48 kg/m3
Liquid Density ρl 906 kg/m3 870 kg/m3
Surface Tension σ 23.21 dyne/cm 24.46 dyne/cm
Molar Weight Mr 123.26 kg/kgmol 93.17 kg/kgmol

𝑳 ƍv
Liquid-Vapor Flow Factor = (FLV) = 𝑽 √(ƍ )
L

Liquid Flow above feed = L = R*D = 351 kg/h

Vapor Rate = V = D (1+R) = 4524 kg/h
Liquid Flow below Feed = Ĺ = R*D + F = 5344 kg/h

(FLV),top = 0.004 (FLV),bottom = 0.054 From Fig. 11.34

Ƃ K(top) = 6.1E-02
Correction for surface tension = (𝟐𝟎)𝟎.𝟐 *K K(bottom) = 8.5E-02
Ƃ(Top) = 24.469 [dyne/cm] After Correction:
Ƃ(Bottom) = 23.211 [dyne/cm] K(top) = 0.063
K(bottom) = 0.087
(ƍL-ƍv)
𝑭𝒍𝒐𝒐𝒅𝒊𝒏𝒈 𝑽𝒆𝒍𝒐𝒄𝒊𝒕𝒚 = 𝑽𝑭 = 𝑲√ ƍv

VF(top) = 1.41 m/s VF(bottom) = 1.42 m/s

Design for 90% at maximum flow rate

VF(top) = 1.27 m/s VF(bottom) = 1.28 m/s

𝑽∗𝑴𝒂𝒗
𝑴𝒂𝒙𝒊𝒎𝒖𝒎 𝒗𝒐𝒍𝒖𝒎𝒆𝒕𝒓𝒊𝒄 𝒇𝒍𝒐𝒘𝒓𝒂𝒕𝒆 = 𝑸 = ƍv

Q(top) = 0.5 m3/s Q(bottom) = 0.48 m3/s

PRODUCTION OF ANILINE FROM PHENOL 84

 EQUIPMENT DESIGN

Net Area Required

𝑄𝑡𝑜𝑝 𝑄𝑏𝑜𝑡𝑡𝑜𝑚
= 0.45 𝑚2 = 0.43 𝑚2
𝑉𝐹,𝑡𝑜𝑝 𝑉𝐹,𝑏𝑜𝑡𝑡𝑜𝑚

Taking Down comer Area as 12% of the total

Column Cross-sectional Area

Top = 0.51 𝑚2 Bottom = 0.49 𝑚2

Column Diameter
Top = 0.80 m Bottom = 0.79 m
Liquid Flow Pattern
𝑳́∗𝑴𝒂𝒗
𝑴𝒂𝒙𝒊𝒎𝒖𝒎 𝑳𝒊𝒒𝒖𝒊𝒅 𝑭𝒍𝒐𝒘𝒓𝒂𝒕𝒆 = = 𝟎. 𝟎𝟎3 𝑚3 /𝐬
ƍL

Fig. 11.35 Single Pass Cross-Flow Plate

Provisional Plate Design

𝐷𝐶 = 0.8 𝑚
𝐶𝑜𝑙𝑢𝑚𝑛 𝐴𝑟𝑒𝑎 = 𝐴𝐶 = 0.51 𝑚2
𝐷𝑜𝑤𝑛𝑐𝑜𝑚𝑒𝑟 𝐴𝑟𝑒𝑎 = 𝐴𝑑 = 0. 061 𝑚2
𝑁𝑒𝑡 𝐴𝑟𝑒𝑎 = 𝐴𝑛 = 𝐴𝐶 − 𝐴𝑑 = 0.45 𝑚2
𝐴𝑐𝑡𝑖𝑣𝑒 𝐴𝑟𝑒𝑎 = 𝐴𝑎 = 𝐴𝐶 − 2𝐴𝑑 = 0.38 𝑚2
𝐻𝑜𝑙𝑒 𝐴𝑟𝑒𝑎 = 𝐴ℎ = 10% 𝑜𝑓 𝐴𝑎 = 0.039 𝑚2

For non-fouling System

Weir Height = 50 mm
Hole Diameter = 5mm
Plate thickness = 5mm

𝑙𝑤
From Fig. 11.39 = 0.77
𝐷𝐶

Weir Length = 0.62 m

Weeping Check
𝐋́∗𝐌𝐚𝐯
𝐌𝐚𝐱. 𝐋𝐢𝐪. 𝐫𝐚𝐭𝐞 = 𝐋𝐰 = = 𝟏. 𝟖𝟕 𝐤𝐠/𝐬
𝟑𝟔𝟎𝟎
𝟐
𝐋𝐰 𝟑
𝐌𝐚𝐱. 𝐖𝐞𝐢𝐫 𝐋𝐢𝐪. 𝐂𝐫𝐞𝐬𝐭 = (𝐡𝐨𝐰 )𝐦𝐚𝐱 = 𝟕𝟓𝟎 × (ƍ )
L∗𝐥𝐰

(how )max = 29.3 mm liq Min how = 25.3 mm Liq

hw = 50 recommended

PRODUCTION OF ANILINE FROM PHENOL 85

 EQUIPMENT DESIGN

At min. rate = hw + ℎ𝑜𝑤 = 75.35 mm Liq

From Fig. 11.37 K = 30.6
(𝑲−𝟎.𝟗𝟎(𝟐𝟓.𝟒−𝒅𝒉 ))
˟𝑈ˆ𝒉 (𝒎𝒊𝒏) = 𝟏
ƍv𝟐

Uˆh (min) = 7.76 m/s

Reduce hole area to 6% of Aa = 0.096 𝑚2
Plate Pressure Drop
𝑼𝒉,𝒎𝒂𝒙 𝟐 ƍv
𝒉𝒅 = 𝟓𝟏( ) ∗
C̥ ƍL

ℎ𝑑 = 5.8 mm Liq
𝟏𝟐.𝟓𝑬+𝟎𝟑
𝑹𝒆𝒔𝒊𝒅𝒖𝒆 𝒉𝒆𝒂𝒅 = 𝒉𝒓 = ƍL

ℎ𝑟 = 13.78 mm Liq

𝑨𝒂𝒑 = 𝑨𝒓𝒆𝒂 𝒖𝒏𝒅𝒆𝒓 𝒂𝒑𝒓𝒐𝒏 = 𝒍𝒘 ∗ 𝒉𝒂𝒑

ℎ𝑎𝑝 = hw-10

𝐴𝑎𝑝 = 0.051 𝑚2
𝑳𝒘𝒅
𝒉𝒅𝒄 = 𝟏𝟔𝟔(ƍ )𝟐
L 𝑨𝒂𝒑

ℎ𝑑𝑐 = .27 mm Liq

𝒉𝒕 = 𝒕𝒐𝒕𝒂𝒍 𝒑𝒓𝒆𝒔𝒔𝒖𝒓𝒆 𝒅𝒓𝒐𝒑 = 𝒉𝒓 + 𝒉𝒅 + 𝒉𝒘 + 𝒉𝒐𝒘,𝒎𝒂𝒙

ℎ𝑡 = 98.97 𝑚𝑚 𝐿𝑖𝑞 = 0.0097 𝑏𝑎𝑟

Froth Height

𝒉𝒅 = 𝒉𝒘 + 𝒉𝒐𝒘,𝒎𝒂𝒙 + 𝒉𝒕 + 𝒉𝒅𝒄

ℎ𝑑 = 178.6 mm liq
Down-comer Residence Time
𝑨𝒅 ∗𝒉𝒅𝒄 ∗ƍL
𝑻𝒓 = 𝑳𝒘𝒅

𝑇𝑟 = 5.47 seconds 𝑇𝑟 ˃ 3 seconds ---Satisfactory

PRODUCTION OF ANILINE FROM PHENOL 86

 EQUIPMENT DESIGN

Entrainment Check
𝑼𝒗 = 𝑸(𝒃𝒐𝒕𝒕𝒐𝒎)/𝑨𝒏
𝑼𝒗
% 𝒇𝒍𝒐𝒐𝒅𝒊𝒏𝒈 = 𝑽𝑭

𝑈𝑣 = 0.25 m/s
𝐹𝐿𝑉 = 0.05 From Fig. 11.29 ψ = 0.036

% flooding = 76 %
Ψ ˂ 0.1 ---Effect on efficiency is small
Perforated Area Calculation
𝑙𝑤
= 0.77
𝐷𝐶

From Fig. 11.40 θ = 102°

Recommendations for Trial Lay-out
• Cartridge Type Construction
• 50 mm unperforated strip round plate edge
• 50 mm wide calming zones

Θ subtended by the edge of the plate = 180-102 = 78°

78
Mean Length, unperforated edge strips = (𝐷𝐶 − (50E − 03))𝜋 ∗ 180 = 2.16 𝑚2

Area of unperforated edge strips = 50E-03*2.16 = 0.145 𝑚2

Mean Length of calming zones = weir Length + width of unperforated strip = 1.61 m

Area of calming zones = 2(1.61*50E-03) = 0.160 𝑚2

Total Area of perforations = 𝐴𝑃 = 𝐴𝑎 − 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑢𝑛𝑝𝑒𝑟𝑓𝑜𝑟𝑎𝑡𝑒𝑑

𝑒𝑑𝑔𝑒 𝑠𝑡𝑟𝑖𝑝𝑠 − 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑐𝑎𝑙𝑚𝑖𝑛𝑔 𝑧𝑜𝑛𝑒𝑠 = 1.34 𝑚2

PRODUCTION OF ANILINE FROM PHENOL 87

 EQUIPMENT DESIGN

Number of Holes
𝜋∗𝐷 2
𝐴𝑟𝑒𝑎 𝑜𝑓 ℎ𝑜𝑙𝑒 = = 1.96𝐸 − 05 𝑚2
4

Number of holes = 1980

Height of Column

No. of Plates = 14

Tray Spacing = 0.5 m

Distance b/w 14 Plates = 14 × 0.5 = 7 m

Top Clearance = 0.5 m

Bottom Clearance = 0.5 m

Tray Thickness = 0.005 m

Total Thickness of Trays = 0.07 m

Total Height of Column = 7. 07 m

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 EQUIPMENT DESIGN

7.5.7 Specification Sheet

Sieve Tray Column

Identification Item: Aniline Tower Date: May 16, 2016

Item No. C-2 By: Ismail Zahoor (2012-CH-39)
No. Required : 2

Function Separation

Operation Continuous

Materials Handled: Feed Overhead Bottom

Quantity 4993 kg/h 4174 kg/h 819 kg/h

Composition Aniline 0.9168 0.9654 0.5910

Phenol 0.0308 0.0345 0.0132

DPA 0.0514 0.0001 0.3958

Temperature: 459 K 457 K 504 K

Design Data: No. of Trays: 14 Reflux Ratio: 0.08

Pressure: 1.15 bar Tray spacing: 0.5m
Total height: 7.07m Diameter: 0.8m
3
Liquid Density: 907 kg/m Vapor Density: 3.3 kg/m3
Max. volumetric flow rate: 0.5 m3/s
Hole size and arrangement: 0.39 m2 (single pass cross flow plate)
Tray Thickness: 5mm

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 EQUIPMENT DESIGN

7.6 Condenser Design

7.6.1 Condensation
When saturated vapors containing an appreciable quantity of latent heat comes into contact
with a surface at a temperature lower than their saturation temperature, vapors losses their
latent heat and gets converted into liquid. This phenomenon is termed as condensation.
Film wise vs Drop wise Condensation
In most of industrial processes film wise condensation is the common phenomenon. Although
the value of heat transfer coefficient is sufficiently high in the case of drop wise
condensation, it is rarely observed.

Horizontal vs Vertical condensers

Table 23: Comparison between Horizontal vs Vertical Condenser

Horizontal Vertical
Heat transfer coefficient is 3.07 times Heat transfer coefficient is smaller
greater
High turbulence Low turbulence
Only condensation is possible Both condensation and sub cooling are
possible
Maintenance is easy Maintenance is somewhat difficult

Both types of condensers have their own specific advantages. However vertical type of
condenser with condensation inside tube is most common industrial application.
Exchange Max. Temperatur Normal Fluid Fluid Key
r type Pressur e Range(0C) area(m2 velocities(m/s limitations features
e ) )
(MPa) (Shell/Tube)
Shell and 30 -200-600 3-1000 Liquid (1- Materials of Very
tube 2)/(2-3) Constructio adaptabl
Gas(5- n e
10)/(10-20) Many
types
Condenser Heat Maximum Fluid Fluid Equipment
type transfer Viscosity (Pa.s) compatibility suitability
area(m2)
Vertical tube 3-200 1.0 Condense Design is very
side organic vapors efficient and
flexible
Cleaning issues

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 EQUIPMENT DESIGN

7.6.2 Selection Criteria for Condenser

Following factors are decisive in the preliminary selection of an appropriate heat exchanger
or condenser:-
 Maximum pressure
 Temperature Range
 Heat transfer area
 Fluid velocities
 Fluid limitations
 Key features

Keeping in mind the above mentioned parameters shell and tube heat exchanger will best fit
our designated design component
Our system fulfills all the above mentioned condition so we have opted vertical tube side
condenser.

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 EQUIPMENT DESIGN

7.6.3 Design of Condenser

Nomenclature:
Q Heat Duty
S Thermal effectiveness factor
R Correction factor
Ft Temperature correction factor
Nt Number of tubes
U Overall Heat Transfer coefficient
PT Tube Pitch
a Flow area per tube
a’’ Surface area of tube
Ac Corrected heat transfer area
at Area of tubes
Gt Tube side mass velocity
C Clearance
B Baffle spacing
as Area of shell
Gs Shell side mass velocity
De Equivalent diameter
tw Pipe wall temperature
tv Average vapor temperature
tf Average condensate film temperature
Uc Clean overall heat transfer coefficient
Rd Dirt factor
F Friction factor
N Number of crosses
∆Ps Shell side pressure drop
∆Pt Tube side pressure drop
∆Pr Return pressure loss
∆PT Total tube side pressure drop
∆PT Total tube side pressure drop

PRODUCTION OF ANILINE FROM PHENOL 92

 EQUIPMENT DESIGN

Calculation of Heat Duty

𝑄 = 𝑚𝜆
Q=199007 KJ/hr
Q=55279.72 W
Coolant Flow Rate
𝑄
m=𝐶
𝑝 ∆𝑇

m=302.635 Kg/hr
LMTD calculation

Th=T2-t1=153.840C
Tc=T1-t2=138.820C
𝑇ℎ −𝑇𝑐
LMTD= 𝑇 LMTD=146.21180C
ln( ℎ )
𝑇𝑐

𝑇 −𝑇
R=𝑡1−𝑡2
2 1

R=0
𝑡 −𝑡
S=𝑇2 −𝑡1
1 1

S=0.0975
Ft=1 (C.a)
LMTDc=Ft×LMTD
LMTDc=146.2118
Finding Nt (Number of tubes)

U (assumed)=500 W/m2.K (C.b)

𝑄
𝐴=
𝑈 × 𝐿𝑀𝑇𝐷
A=3.8287 m2
Tube specifications (C.c)
OD=0.0190 m2
BWG=18
ID=0.0166m2

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 EQUIPMENT DESIGN

Length of tube= 2.44m

Tube Pitch= 𝑃𝑡 = 1.25 × 𝑂𝐷=0.0238m
Flow area per tube (a) =2.156E-4m2
Surface area of tube (a’’) =𝜋DiL=0.1272m2
𝐴
𝑁𝑡 = 𝑎′′ =30.1=30 (C.d)

𝐴𝑐 = 𝑁𝑡 × 𝑎′′ =3.816m2
𝑄
U (calculated) =𝑈 =501W/m2.K
𝑐 ×𝐿𝑀𝑇𝐷

U (calculated) is approximately equal to U (assumed)

Tube side calculations
𝑁𝑡 × 𝑎
𝑎𝑡 =
𝑛
n= number of tube passes
at=0.0032m2
𝑚
𝐺𝑡 =
𝑎𝑡
Gt=40806039 Kg/m2/sec
𝐼𝐷 × 𝐺𝑡
𝑅𝑒 =
μ
Re=97709.4099
𝐺𝑡
𝑣=
𝜌
V=2.71 m/sec
hi=5955 W/m2.K (C.e)
𝐼𝐷
ℎ𝑖𝑜 = ℎ𝑖 × 𝑂𝐷=5183.15 W/m2.K

Shell side calculations

Shell ID=0.2033m (C.f)

Clearance=C=0.011m (C.g)
Baffle Spacing=𝐵 = 0.7 × 𝐼𝐷=0.1423 m
𝐼𝐷 × 𝐶 × 𝐵
𝑎𝑠 =
𝑃𝑡

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 EQUIPMENT DESIGN

as=0.0366 m
𝑚𝑠
𝐺𝑠 =
𝑎𝑠
Gs=4636029 Kg/m2/sec
𝑊
𝐺 ′′ = 2⁄
𝐿𝑁𝑡 3

G(loading)=46.36 Kg/m2/K
De= 0.0139m (C.h)
ho (assume) = 1100 W/m2.K
Tv= 183.840C
tw=62.540C
𝑇𝑣 + 𝑡𝑤
𝑡𝑓 =
2
tf=123.190C
sf= 0.60 (C.i)
µf=0.0002 Pa.s (C.j)
kf= 0.077 W/m2.K/m
ho=1070 W/m2.K (C.k)
𝐺𝑠 × 𝐷𝑒
𝑅𝑒 =
𝜇
Re=62458
ℎ𝑖𝑜 × ℎ𝑜
𝑈𝑐 =
ℎ𝑖𝑜 + ℎ𝑜
Uc=886.908 W/m2.K
𝑈𝑐 − 𝑈𝑑
𝑅=
𝑈𝑐 × 𝑈𝑑
Rd=0.001 (C.l)
1 1
= + 𝑅𝑑
𝑈𝑑 𝑈𝑐
Ud=470.03 W/m2.K
This value of Ud is somewhat close to our assumed value of 500 W/m2.K.

PRODUCTION OF ANILINE FROM PHENOL 95

 EQUIPMENT DESIGN

Pressure drop calculations

Shell side pressure drop

f= 0.0027 (C.m)
𝐿𝑡
𝑁 + 1 = 12
𝐵
N+1=10
0.5(𝑓𝐺𝑠 2 𝐷𝑠(𝑁 + 1))
∆𝑃𝑠 =
5.22 × 1010 𝐷𝑒𝑆
∆Ps=13.8 kPa
Tube side pressure drop

f=0.0005
𝑓𝐺𝑡 2 𝐿𝑛
∆𝑃𝑡 = 5.22×1010 𝐷𝑠𝜑𝑡

∆Pt= 62.8 KPa

𝑉2
=0.003 (C.n)
2𝑔

∆Pr=6.7 KPa
∆PT=69.5KPa
∆PT=69.5KPa

PRODUCTION OF ANILINE FROM PHENOL 96

 HAZOP STUDY

CHAPTER 8

HAZOP STUDY

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 HAZOP STUDY

8 HAZOP STUDY
8.1 Hazard and operability studies:
A hazard and operability study is a process for the orderly, critical, inspection of the operability
of a process. When applied to a process design or an operating plant, it specifies potential
hazards that may rise from deviances from the anticipated design conditions.
8.2 Basic Principles:
A proper operability study is the orderly study of the design, equipment by equipment, and line
by line, using “guide words” to help create thought about the way deviances from the proposed
operating situations can cause hazardous circumstances. The seven guide words commended
in the CIA booklet. In addition to these words, the subsequent words are also used in a different
way, and have the specific meanings given beneath:[19]
Intention: intention tells us that about the intention behind the particular process or equipment,
intention of designer.
Deviations: deviation tells about deviation from the intended operation the equipment under
consideration.
Causes: cause tells about the reason behind the deviation from intended operation.
Consequences: what are the consequences of the deviation?
Basic Guide words:
Table 24: HAZOP Key Words

Guide words Meanings Comment

Complete negation of
NO or NOT No part of intention is achieved
intention
This specifies the quantities and properties
More quantitative increase
such as flow rates and temperature
This specifies the quantities and properties
Less Quantitative decrease
such as flow rates and temperature
All operating and designed intentions are
AS WELL AS Qualitative increase
achieved with additional activities
PART OF Qualitative decrease Some of the designed intentions are achieved
Logical opposite of the
REVERSE Reverse of the intentions is happening
intention
No part of the desired intention is achieved
OTHER THAN Complete substitution
but something quite different is happening.

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 HAZOP STUDY

Hazard and operability study around ammonia vaporizer.

8.3 Vessel – Ammonia vaporizer
Intention – evaporate liquid ammonia at 16 bar to 425oC

Figure 8: Ammonia Vaporizer Instrumentation

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 HAZOP STUDY

Table 25: HAZOP Guide Words for Ammonia Storage

Guide word deviation cause Consequences and action

Line No. P1 Intention transfer liquid NH3 from storage

NO flow Pump failure Level falls in vaporizer: fit

CV1 failure low-level alarm (LA1)
LESS flow Partial failure (LA1) alarms
Pump/valve
MORE flow CV1 sticking, Vaporizer floods, liquid to
LCI reactor: fit high-level alarm
(LA2) with automatic pump
shut-down
AS WELL AS Water brine Leakage into Concentration of NH4OH in
storages vaporizer: routine analysis,
from maintenance
refrigeration
REVERSE Flow Pump fails, Flow of vapor into storages:
vaporizer (LA1) alarms; fit non-return
Press. higher valve (NRV2)
than
delivery

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 HAZOP STUDY

Table 26: HAZOP Guide Words for Ammonia Storage Line 2

Line No. P2 Intention transfers vapor to mixing tee

NO flow Failure of steam flow, (LA1) alarms,
CV3 fails closed reaction ceases:
considered low
flow alarm,
rejected needs
resetting at
each rate
LESS Flow Partial failure or As no flow
blockage CV3
MORE Level flow LC1 fails LA2 alarms
FR2/ratio control Danger of high
miss-operation ammonia
concentration: fit
alarm, fit
analyzers
(duplicate) with
high alarm 12 per
cent NH3
(QA1, QA2)
REVERSE Level flow LC1 fails LA2 alarms
Steam failure Hot, acid gases
from
Reactor-
corrosion: fit non-
return valve
(NRV3)
Line S1 (auxiliary) CRV2 fails, High level in
trap frozen vaporizer: LA2
actuated

After HAZOP study instrumentation is added to look after these deviations.

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 ENIVROMENTAL IMPACT ASSESSMENT

CHAPTER 9

ENVIROMENTAL
IMPACT ASSESSMENT

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 ENIVROMENTAL IMPACT ASSESSMENT

9 ENVIRONMENTAL IMPACT ASSESSMENT

9.1 Environmental Impact Assessment
What is EIA?

An environmental impact assessment (EIA) report is an evaluation of the possible positive or

negative impacts that a proposed project may have on the environment, consisting of the
environmental, social and economic aspects.

The purpose of the assessment is to ensure that decision makers consider the ensuing
environmental impacts when deciding whether or not to proceed with a project. The
International Association for Impact Assessment (IAIA) defines an environmental impact
assessment as "the process of identifying, predicting, evaluating and mitigating the biophysical,
social and other relevant effects of development proposals prior to major decisions being taken
and commitments made." [1]
9.2 Importance of EIA
EIA today is being used as a decision aiding tool rather than decision making tool. It aims at
identifying, predicting, evaluating and mitigating the biophysical, social and other relevant
effects of development proposals prior to major decisions being taken and commitments made.
EIA brings together number of points that must be considered prior to decision making. It
makes it easy to identify
o The most environmentally suitable option at an early stage.
o Alternative processes.
9.3 Contents of an EIA report
An effective EIA report should cover the following aspects
o A description of the project: location, design, size etc.
o Description of significant effects.
o Mitigating Measures
o A Non-Technical summary.
9.4 Step Wise Structure of EIA
There are 10 basis steps, following which leads to an effective EIA report. These steps are
mentioned below

9.4.1 Preliminary Activities & TOR

Preliminary activities include the defining of the Terms of Reference (TOR) for the project and
also the determining of the personnel required for the assessment. A brief summary of the

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 ENIVROMENTAL IMPACT ASSESSMENT

project is extremely helpful at this stage. The summary should be clear and explicit and should
list exactly what the development project entails.

9.4.2 Scoping
Scoping is the process of deciding which of a project’s possible alternatives and impacts should
be addressed in the EIA. Scoping is carried out in discussions between the developer, the
competent authority, relevant agencies and, ideally, the public.

9.4.3 Baseline Studies

The baseline study should anticipate the future state of the environment assuming the project
is not undertaken. Following the scoping phase, it is essential to assemble all the relevant
information on the current status of the environment. This provides the ‘baseline’ against which
future impacts can be assessed. Baseline studies should be undertaken for each alternative site
so that the relative severity of the impacts for each alternative can be assessed.

9.5 Alternatives
Alternatives are the ‘raw material’ of EIA. EIA is ideally undertaken for a project and its
alternatives (e.g. different locations, scales, designs). The US Council on Environmental
Quality (CEQ) has described the discussion of alternatives as the ‘heart’ of the EIS
(Environmental impact Statement).

9.5.1 Impact Prediction

Impact prediction involves the prediction of the negative and positive consequences a project
is expected to have on the environment and public. All social, economic, socio-cultural and
environmental impacts are considered in this step.

9.5.2 Impact Assessment

Impact assessment involves evaluating the significance of the impacts identified. Significance
can be determined through professional judgment, reference to regulations etc. The conclusions
of the impact assessment can ultimately be used by decision-makers when determining the fate
of the project application.

9.5.3 Mitigation
Negative impacts on the environment identified during the EIA can be alleviated through
mitigation measures. Impacts remaining after mitigation are known as residual impacts.

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 ENIVROMENTAL IMPACT ASSESSMENT

9.6 EIS Preparation/Review

Once complete, the EIS is submitted to the competent authority (along with the planning
application). The EIS is often reviewed (either formally or informally).The review enables the
competent authority to decide whether the EIA is adequate, accurate and unbiased.

9.6.1 Public Consultation and Decision Making

The EIA Directive provides for public consultation on the application for development and the
EIS. Decision-making is the process which starts after the above-mentioned steps of EIA are
completed. Usually the decision is taken by a manager or a committee, or personnel from the
concerned ministry who had not been associated with the EIA during its preparation. Technical
and economic aspects of project alternatives are thoroughly considered but, at times, political
expediency and project feasibility control the final choice. In general, a decision-maker has
three choices:

 Accepting one of the project alternatives

 Returning the EIA with a request for further study in certain specific areas
 Totally rejecting the proposed project along with alternative versions

9.6.2 Project Monitoring

Monitoring should determine:

 The accuracy of the original predictions

 The degree of deviation from the predictions
 The possible reasons for any deviations
 The extent to which mitigation measures have achieved their objectives [20]

9.7 EIA of NH3 Removal Section Air Emissions

The Low Air Ratio process is the cleanest of the processes for Phthalic anhydride production.
Normal operating conditions will produce only two significant discharges to the environment.

 Non-condensable reaction by-products that remain with the air as it is rejected from the
process to the environment;
 Heavy residue from the bottoms of the rectification column.

The following mitigation measures are taken to minimize the adverse effects of the plant on
the air;

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 ENIVROMENTAL IMPACT ASSESSMENT

1. A scrubbing unit will be installed in order to reduce the concentrations of

contaminants to less than 25 ppm PAN, 10 ppm maleic anhydride and 3 ppm benzoic
acid prior to discharge to the atmosphere.
2. A 50 m stack will disperse these concentrations to acceptable levels.
3. The rectification column bottoms will be transferred to another local chemical
manufacturer for reprocessing to recover valuable components and, therefore, will
not contribute to daily emissions

9.8 Water Emissions

Water does not come into direct contact with any process stream in the Phthalic anhydride
process. Air coolers are used to satisfy most of the process cooling requirements minimizing
the cooling water requirements. However, there will still be a cooling water link with the joint
venture utilities plant that will service several local industries, and small amounts of PAN and
other organic products could possibly enter the shared cooling-water system.

Through economies of scale, the utilities plant is able to use the latest technology (e.g.
automated dosing pumps, on-line analyzers and advanced control applications) to remove
contaminants and minimize emissions to the environment. The cooling-water circuit is a closed
system and does not use either sea or river water, and it makes only small discharges of pH-
neutral water to the environment.

Biological fouling is controlled with phosphate additives rather than the more environmentally
hazardous chromate additives. [4]

Steam requirements will be essentially met by the process itself using the heat generated by the
PAN reaction. Process contaminants that might enter the steam system through exchanger leaks
or other process disturbances will be scrubbed at the shared utilities plant, so that condensate
can be recycled to reduce energy consumption and chemical treatment costs.

9.9 Noise Pollution

Sources of construction noise include:

1. Construction vehicles and plant

2. Construction camp noise
3. Pile driving
4. Other special localized activities.

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 ENIVROMENTAL IMPACT ASSESSMENT

Besides this, the Phthalic anhydride plant has a significant number of major noise sources
during the operational phase, including:

1. Compressors
2. Turbines
3. Air Coolers;
4. Fans (Flue gas, and Combustion air);
5. Pumps
6. Flares.
7. Vents

9.10 Potential Health Effect

There is a need for limiting the risks; risk reduction measures which are already being applied
shall be taken into account.

This conclusion is reached because of concerns for mutagenicity and carcinogenicity as a

consequence of exposure arising from use of products containing the substance, as aniline is
identified as a non-threshold carcinogen.

9.11 First Aid Measure.

Always seek professional medical attention after first aid measures are provided.

 Eyes: Immediately flush eyes with excess water for 15 minutes, lifting lower and upper
eyelids occasionally.
 Skin: Immediately flush skin with excess water for 15 minutes while removing
contaminated clothing.
 Ingestion: Call Poison Control immediately. Rinse mouth with cold water. Give victim
1-2 cups of water or milk to drink.
 Induce vomiting immediately.
 Inhalation: Remove to fresh air. If not breathing, give artificial respiration.

9.12 Fire Fighting Measure

Combustible liquid. When heated to decomposition, emits acrid fumes. Volatile with steam.
Protective equipment and precautions for firefighters: Use foam or dry chemical to extinguish
fire. Firefighters should wear full firefighting turn-out gear and respiratory protection (SCBA).
Cool container with water spray. Material is not sensitive to mechanical impact or static
discharge.

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9.13 Accidental Release Measure

Use personal protection recommended in Section 8. Isolate the hazard area and deny entry to
unnecessary and unprotected personnel. Sweep up spill and place in sealed bag or container for
disposal. Wash spill area after pickup is complete.

9.14 Handling and Storage

 Handling: Use with mechanical ventilation only and do not breathe vapor. Avoid
contact with skin, eyes, or clothing. Wash hands thoroughly after handling. Respiratory
use is forbidden, ineffective protection.
 Storage: Store in Toxic Storage Area [Blue Storage] with other toxic material. Store in
a dedicated poison cabinet. Store in a cool, dry, well-ventilated, locked store room away
from incompatible materials.

9.15 Exposure Control/ Personal Protection

Use ventilation to keep airborne concentrations below exposure limits. Have approved eyewash
facility, safety shower, and fire extinguishers readily available. Wear chemical splash goggles
and chemical resistant clothing such as gloves and aprons. Wash hands thoroughly after
handling material and before eating or drinking. Use NIOSH-approved respirator with an
acid/organic cartridge. Exposure guidelines: Aniline: OSHA PEL: 19 mg/m3; ACGIH: TLV:
7.6 mg/m3, STEL: N/A.

PRODUCTION OF ANILINE FROM PHENOL 108

 HYSYS SIMULATION

CHAPTER 10

ASPEN HYSYS
SIMULATION

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 HYSYS SIMULATION

10 ASPEN HYSYS SIMULATION

10.1 Keywords
Aspen HYSYS, Aniline Production, Halcon Process, Energy Efficient, Aspen Energy
Analyzer, Heat Integration
10.2 Objectives
1. To model the Halcon process
2. Perform the pinch analysis to optimize the system
3. To compare the Simulation results with hand calculation
10.3 Introduction
Halcon process is used to produce Aniline from the reaction of phenol and ammonia the
resulting components are the water, diphenylamine. These are the components which will be
used in the whole process simulation.[21] Phenol at the flowrate of 54.54 kmol/hr is to be
introduced at 25oC and 18 bar in shell and tube heat exchanger E-100. Phenol is preheated and
vaporized to gain temperature of 322oC and 17 bar in E-100 using reactor outlet products
having temperature and pressure of 434oC and 16 bar. The exit temperature of reactor effluent
after E-100 is 345oC and have pressure of 15.30 bar. Finally, phenol is superheated in E-103 to
meet the reactor specification having temperature and pressure of 425oC and 16 bar. Stream #
3 is fed again to heat exchanger E-101 to pre-heat and vaporize the liquid ammonia from 25oC
and 17.5 bar to 42.6oC and 16.7 bar pressure while the stream 4 after exchanging heat have
temperature of 59.66oC. These saturated vapor of ammonia are superheated in E-104 to 425oC
and 16 bar. The whole reaction is carried out in the vapor phase to gain maximum
conversion.[22] Conversion reactor is used to carry out the reaction where one major reaction
is take place having 96% conversion of phenol while a side reaction having only 7% conversion
take place parallel to the main reaction.[23]
C6 H6 − OH + NH3 → C6 H6 − NH2 + H2 O
C6 H6 − OH + C6 H6 − NH2 → C6 H6 − NH2 − C6 H6 + H2 O
To meet the stripper requirement stream 4 is cool down and converted into saturated liquid in
cooler E-102 i.e. 40.43oC and 13 bar. Reboiled stripper is used in this process because we
want to remove unreacted ammonia from the rest of product.[17]

Figure 9: Process Flow Diagram of Halcon Process

Reboiled stripper is used because ammonia has high relative volatility as compared to other
components so instead of using steam or gas stripping, reboiled stripper which is similar to

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 HYSYS SIMULATION

distillation column is used to avoid the separation of gas or water from ammonia. Almost 99%
of the ammonia is to be removed using stripper and recycle back to reactor.[17] Water is also
removed using “automatic water draw” feature from the bottom of stripper. To carry out further
separation to recover aniline from the heavy components we need to operate the distillation
column at atmospheric pressure so flashing is carried out using throttle valve to reduce the
pressure from 13.054 bar to 1 bar. Saturated liquid feed at 128oC is introduced to aniline
recovery column to separate aniline from the phenol and diphenylamine.
10.4 Methodology
10.4.1 Modeling Strategy
To carry out the simulation of any model; which is the hypothetical or imagination of that
equipment; we have to fulfil the degree of freedom. For that purpose, material stream is also
very important in chemical process plant. Ones can easily specify the stream by mentioning the
feed flowrate, composition, temperature and pressure of the stream. [24]
In my case shell and tube heat exchanger also has crucial rule in the chemical industry to cool
or heat the process streams. To model the HX ones must specify the inlet and outlet temperature
as well as pressure drop to perform the calculation. One of the most valuable thing to model
any heat exchanger is to specify the location of hot and cold fluid. According to chemical
engineering heuristics, we also prefer the location of condensing or vaporizing stream on the
shell side because when liquid is vaporized it require more volume that is why shell side is
convenient.[25]
The reactors are the vessels where most of the time catalyst is used to initialize and to carry out
the reaction. This is possible only because of suitable kinetics of the reactors and the essential
part is the proper selection of catalyst. To simulate the reactors there are number of ways to
specify the reaction set but in our case conversion reactor is the most suitable one. To model
this equipment we have to specify the reaction kinetics to obtain proper results.[26]
Stripper and distillation column modeling is the most rigorous one because to perform the
rigorous calculation on each stage we should have operating line and equilibrium line for each
tray. In deep insight ones require the efficiency of each tray to calculate the actual no of stages
but for more accurate results we have to take care about component efficiency too. Considering
all these things in the distillation column imparts crucial rule in the modeling of distillation
column. If we talk about the control of distillation column, it also requires bit special attention
to maintain the composition of distillate. To control the temperature and pressure of column
ones have knowledge about reboiler significance and condenser. [27]
10.4.2 Simulation Approach
To begin the simulation using Aspen HYSYS, run the software and create new simulation file
and then entre all the components which are being processed in the either section of plant. In
my case, ammonia, phenol, aniline, water and diphenylamine are the components.
To perform the thermodynamics calculation, we have to select the appropriate thermodynamics
property package according to the system. For Halcon process to manufacture aniline which is
comes under the class of amines I choose UNIQUAC activity model. The possible reason for
selecting UNIQUAC model is that it is significantly more detailed and sophisticated than any
of the other activity models. Its main advantage is that a good representation of both VLE and
LLE can be obtained for a large range of non-electrolyte mixtures using only two adjustable

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parameters per binary. The fitted parameters usually exhibit a smaller temperature dependence
which makes them more valid for extrapolation purposes. It is the most suitable
thermodynamics fluid package for the range of hydrocarbon classes i.e. for esters, aldehydes,
ketones, amines etc.
To model the reactors using Aspen HYSYS v8.8, in properties tab look for reaction tab and
create the reaction set and entre the possible reaction in the same reaction set by specifying the
conversion and stoichiometric coefficient; negative sign with reactants and positive sign with
product. After creating the reaction set, attach the set with fluid package. After performing
these steps return to simulation environment.
Phenol and ammonia is to be heated, vaporized and then superheated from the 25oC to 425oC
using series of heat exchanger. Pre-heating and vaporization of both reactants is to be done
using the reactor effluent stream. To fully specify ammonia stream, we have to entre
temperature 25oC, pressure 17.5 bar, flowrate 1.854E4 kg/h and the composition of the
ammonia comes to be 1. When all the required inputs are completed, in status bar “OK” will
be appeared. Similarly, after putting shell and tube heat exchanger on flowsheet, we have to
make sure the stream connectivity in right way with appropriate pressure drop and temperature
across the exchanger. Aspen HYSYS automatically keep on calculating the maximum possible
results from the given information but make sure HYSYS solver is active. After properly
specifying the user model and computing the results, outputs can be viewed by opening
worksheet. Blue color shows information is provided by user and editable. Figure 1-1 shows
the results for E-101.

Figure 10:Ammonia Pre-heater and vaporizer

Similarly, phenol is also pre-heated and vaporized to its saturation point in heat exchanger E-
100. To fully specified the phenol entre temperature of phenol feed as 25oC, pressure of Phenol-
1 stream is 18 bar having mass flowrate of 5133 kg/h. Specify the vapor fraction 1.00 of phenol
stream at the outlet of E-100 which indicate saturated vapor having 322.8oC temperature.

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Aspen HYSYS automatically calculate the hot stream outlet temperature afterward. All the
relative calculations with properties computed by HYSYS can be seen in properties tab.

Figure 11: Phenol Pre-heater and vaporizer

Now, superheat the phenol and ammonia saturated vapor to 425oC to and 16 bar to meet the
reactor conditions using E-103 and E-104 exchanger. These results are presented in Figure 3
and 4.
Conversion reactor is used to carry out the reaction for aniline production where in first major
reaction phenol conversion is 96% while in side reaction conversion of phenol is 7%.
C6 H6 − OH + NH3 → C6 H6 − NH2 + H2 O
C6 H6 − OH + C6 H6 − NH2 → C6 H6 − NH2 − C6 H6 + H2 O
Connect the stream in a proper way and add reaction set to the reactor. After calculation, as
reactor is to be operated adiabatically, that is why heat of reaction is also added to the system
which results in increase in the outlet temperature. All the possible results i.e. translation of
input, composition, temperature conditions etc. obtained from the conversion reactor are
displayed in the Figure 5, 6, 7 and 8.
Afterward reactor stream # 1; reactor effluent cool down by heating the feed stream this thing
keeps on increasing the efficiency of the whole process. That’s why our system is 50.47%
energy efficient which is remarkable optimization.

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Figure 12:Phenol Superheater

Figure 13: Ammonia Superheater

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Figure 14: Reactor Inputs

Figure 15: Reactor worksheet

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Figure 16: Reactor's stream composition

Figure 17: Reactor Summary

E-102 is the cooler which further decrease the temperature to meet the stripper requirement i.e.
40.43oC and pressure of 13 bar. Results are available in figure 9.

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 HYSYS SIMULATION

At that stage reactor effluent have blackish color and to purify this product we need to strip out
the ammonia from the product we are using reboiled stripper which is typical type of distillation
column without rectification section.[28] One more reason to use the reboiled stripper in this
case is that being light key it has higher K-value and easy to strip out. So feed is introduced
from the top most stage of the column having total 20 no. of stages. From the hand calculation
and design specification, pressure drop of 0.054 bar is to be observed which is to be
accommodated in this column.[28] Ammonia leave the column at the same temperature of feed
because in equilibrium there is no change is temperature between liquid and vapor. Traces of
water also leave with ammonia and the rest of product extracted from the bottom having
260oC.[29]

Figure 18: Stripper specification

In this stripper we are also removing the water from the bottom of column to make the aniline
purer and also to prevent the formation of azeotrope. While specifying the column we have to
provide the distillate flowrate to model the stripper. As a result, the whole column results can
be executable when the degree of freedom turns to zero and we can check the DOF status in
the Monitor under Design tab. All possible results are will be available after running and
converging the column. In my case water is also being drawn from the column that is why in
status bar “Converged – AWD” is appearing Figure 16. Column results are as follows:
Figure 10 shows that pressure drop across the whole column have linear trend.

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Figure 19: Pressure vs Tray position of column

Ones can browse the sizing of stripper from towers, vessels i.e. reboiler etc. under the Rating
tab.

Figure 20: Sizing of main tower

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 HYSYS SIMULATION

Figure 21: Sizing of Reboiler

Figure 22: Column Worksheet

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Figure 23: Column streams composition

Figure 24: Component flowrates

The most thing in column are the internals, to determine the column internals click on
Equipment sizing and then Tray sizing. In our case, we used sieve tray and its results are as
follows.

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Figure 25: Auto Water Draws (AWD)

Figure 26: Column Internals

To further pure the components, we have to reduce the temperature and pressure of bottom
stream no 8. This can be done by flashing; using throttle valve and heat cooler. As a result,

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pressure of 1 bar is maintained while the temperature kept on the stream liquid saturated point
for the normal operation of column. Results are as follows.

Figure 27: Flashing results

Figure 28: E-105 Cooler

Then stream 10 is fed to the conventional distillation column i.e. Aniline Rec-1 having column
specification a follows:

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Figure 29: Input specifications for Aniline Rec-1

Figure 30: Temperature profile of Aniline Rec-1

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Figure 31: Aniline Rec-1 tower sizing

Condenser as well as reboiler rating is also available in this case.

Figure 32: Aniline Rec-1 streams results

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Figure 33: Aniline Rec-1 reboiler & condenser sizing

Figure 34: Aniline Rec-1 streams composition

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Figure 35: Components recovery in Aniline Rec-1

Figure 36: VL flowrate in condenser & reboiler

Similarly results for Aniline Rec-2 are available and final the distillate streams concentrated in
aniline are combined in MIX-101 and stored after decreasing temperature in E-107 to 25oC and
1 bar pressure. The results are as follows.

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Figure 37: Aniline mixer-101

Figure 38: Aniline storage cooler

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Figure 39: Aniline storage tank

Figure 40: Aniline storage tank results summery

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10.4.3 Analysis
The biggest advantage to use the Aspen technology software is the integrated network from
where we can move to each end to analyze the system and made modification on the basis of
those results. After performing the simulation using Aspen HYSYS, I performed the pinch
analysis to integrate the system using Aspen Energy Analyzer. According to those results I
developed 50% energy efficient process to manufacture the aniline.
Actually, pinch technology is the concept of thermodynamics and used to locate the optimize
energy in the process using integration of energy. The biggest advantage of pinch technology
is that it is used to set the energy target that is it is preferred over old design concepts. [30]
The results obtained after performing the pinch analysis are as follows. Which show that total
actual utilities have heat flow of 1.5E7 kcal/h while energy flow required for the process is
much less that the actual heat flow i.e. 7.42E6. this results in make the system 50.47% energy
efficient. That actual utilities heat flow comes from the addition of both heating and cooling
utilities which combine make the system sustainable and energy efficient. Other pinch analysis
results and figures are also available.

Figure 41: Energy target for Halcon process

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Figure 42: Pinch Analysis over the plant

10.5 Results and Discussion

In the whole simulation we are able to produce the 96% pure aniline. More purity can be
achieved in the real plant if we put the vacuum distillation to avoid the azeotrope formation.
But in this case we remove the water so that azeotrope should not form. This is important
because while operating the distillation column on vacuum the volatility of phenol is inhibited
which help the aniline to recover more in the distillate. Ammonia is striped out using reboiled
stripper because in case of using gas stripper, which is recommended method in most cases to
remove ammonia from liquid, separation cost to separate the ammonia from air is increased.
The other way to strip out the ammonia is to use the steam stripping which is not carried out in
this Halcon process only to avoid the separation cast.
10.6 Conclusions and Recommendations
Modeling is representative of the real world equipment which has no match for real system.
All the models are useful for development. Although, Halcon process is the most efficient
process for aniline production but still there is room of improvements. According to the modern
world those process is acceptable which are environment friendly and the most importantly
should be sustainable. In sustainable process, our aim is to extract maximum from the given
process so that waste or disposal of material is minimized. It is recommended that make the
Halcon process more energy efficient and reduce the carbon emission from the utilities so that
it can meet the standards of new sustainable development.

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 COST ESTIMATION

CHAPTER 11

COST ESTIMATION

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11 COST ESTIMATION
11.1 Overview
Already the plant to be functioned, indicated money must be provided to procurement and
install the equipment. The capital desired to supply the essential plant services is called fixed
capital investment though that for the functioned of the plant is called the working principal
and addition of two funds is called total capital investment. An adequate plant design must
represent a process that is proficient of functioning under conditions which will return a profit.
Since, Gross profit total income-all expenses. It is important that chemical engineer be attentive
of the unlike types of cost involved in developed methods. Capital must be assigned for direct
plant expenses.

Cost Estimation
Name Summary
Total Capital Cost [USD] 1263500
Total Operating Cost [USD/Year] 914350
Desired Rate of Return [Percent/'Year] 20
Equipment Cost [USD] 2114300
Total Installed Cost [USD] 4011500

Utilities
Name Fluid Rate Rate Units Cost per Hour Cost Units
Electricity 722.597 KW 56.001267 USD/H
Cooling Water Water 0.127038 MMGAL/H 15.24456 USD/H
Steam @400PSI Steam 9.897273 KLB/H 115.897067 USD/H

Unit operation
Name Equipment Installed Equipment Installed Utility
Cost [USD] Cost Weight Weight Cost
[USD] [LBS] [LBS] [USD/HR]
Dehydration Scrubber 18600 95400 3600 11098 0
Stripper 142400 416600 30300 79011 0
Heat Exchanger 1 18300 84700 4100 15749 0
Dehydration Column 134200 461200 26700 79392 98.839785
Heat Exchanger 2 28200 109400 7900 23156 6.84024
Compressor 769600 920300 11700 28091 20.23525
Cooler 11200 59900 1600 6606 1.06584
Heat Exchanger 3 9600 60800 990 7185 1.07736
Aniline Recovery 87100 360800 14140 51211 22.552922
Heat Exchanger 4 11800 110900 1500 11556 0

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11.2 Purchased Equipment

The cost of purchased equipment is the basis of several predesign methods for estimating
capital investment.
The various types of equipment can often categorized into:
1. Processing Equipment
2. Raw Material Handling
3. Finished Product handling

Equipment
Name Equipment Installed Equipment Total Installed
Cost [USD] Cost [USD] Weight Weight [LBS]
[LBS]
Heat Exchanger 1 18300 84700 4100 15749
Heat Exchanger 3 9600 60800 990 7185
Heat Exchanger 4 11800 110900 1500 11556
Heat Exchanger 2 28200 109400 7900 23156
Compressor 769600 920300 11700 28091
Valve 67900 180800 21000 54096
Heat Exchanger 5 8500 59500 560 6701
Heat Exchanger 5 16700 76500 3700 12084
Stripper 103000 272300 19000 41090
Reboiler Stripper 39400 144300 11300 37921
Condenser Aniline Recovery 8400 59400 540 6681
Reboiler Aniline Recovery 11600 79100 1700 14209
Aniline Recovery Tower 67100 222300 11900 30321
Reboiler Dehydration 25200 108900 6200 25180
Condenser Dehydration 10900 62300 1500 7750
Dehydration Tower 98100 290000 19000 46462

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 INSTRUMENTATION

CHAPTER 12

INSTRUMENTATION

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12 INSTRUMENTATION
12.1 Instrument
An instrument is a device that calculates and/or controls process variables such as level,
temperature flow or pressure. Instruments comprise of many varied contraptions which can be
as
modest as valves and spreaders, and as multifaceted as analyzers. Instruments often include
control systems of diverse processes such as refineries, factories, and vehicles. The controller
of processes is one of the key branches of applied arrangement. Instrumentation can also refer
to handheld strategies that measure some anticipated variable and with the help of control loop
we are capable to control the anticipated variable value into satisfactory limits. Basically
process control has three main inducements.
• Suppressing the influence of external disturbances.
• Ensuring the stability of a chemical process.
• Optimizing the performance of a chemical process.
These are the key incentives of process controller. Process controller is the main object any
process plant since without control, once disturbance originates into the system. The whole
plant will be shut-down and production will be stopped. There are few more objectives of the
process control, which is given below:
• Safe plant operation
• Production rate.
• Product quality.
• Cost.
12.2 Main Process variables & their Control

Pressure, temperature and flow rate, these are the key process variables on which the whole
process is founded. Their measurement and control is specified below:
Temperature Measurement & Control

One of the key process variables is temperature and its control is very much significant. As in
all the process equipment where an assured temperature compulsory, we placed temperature
control there. Initially, the temperature is to be unrushed by one of the primary instruments:
• Thermocouples.
• Thermistors.
• Electrical resistance change (RTD).
• Pyrometers.
• Expansion of materials.
As the temperature is being measured by the aid of any these devices secondly, we handle it
with the help of any control loop. Usually, we use thermocouples for temperature
measurements and feedback control loops.

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Pressure Measurement & Control

The temperature and pressure are valuable indications of material state and composition. In
fact, these two measurements considered together are the evaluating devices of industrial
materials. In compressed gas systems etc., pressure is of primary importance; pumping
equipment are furnished with pressure measuring devices. Few pressure measuring devices are
listed below:
• Bourdon tube pressure gauge.
• Diaphragm pressure transducers.
• Bellows.
As the pressure is measured with the help of any these gauges secondly we control it with the
help of any control loop. Normally we use Bourdon tube pressure gauges for pressure
measurement and feedback control loop for its control.

Flow Measurement & Control

Flow measurement is very significant in a process plant control, for product value and safety
details. Custody transmission, both interplant and selling to outside customs. Flow control is
also significant in satisfying containers, stock-tanks and transporters. Energy and mass
balancing for the estimate determination and health monitoring of heat exchangers. Health
nursing of pipelines and on-line examination equipment. The common types of flow meters are
given below:
• Differential Pressure Meters.
• Rotary Meters.
• New Flow Meters.
• Point Velocity Meters.
• Mass Flow Maters.
Moreover, for these flow meters usually feedback control loop is used. So that the Flow rate of
the stream is to be measured.

12.3 Control Loops

In addition to instrumentation, there are control loops also there which regulates the control
elements such as the whole process reaches to steady state. Instruments are just like the eyes,
where controller is feed with the artificial intelligence so that the things observe by the
instruments can be control after comparison with the set point value. There are few control
loops mentioned below:
• Feed forward control loop.
• Feedback control loop.
• Ratio control loop.
• Auctioneering control loop.
• Split range control loop.
• Cascade control loop.

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12.3.1 Feed Forward Control Loop

Control formation in which the significance of disturbance is measured originally before it goes
to the system and then, action is taken to avoid the disturbance by altering the value of a process
variable. This is a control method intended to avoid errors from happening in a process variable.
This control system is improved than feedback control because it forestalls the change in the
process variable beforehand it enters the process and takes the defensive action. While in
feedback control system action is occupied after the change has happened. Feed forward
control loop is quite good but very costly.
12.3.2 Feed Backward Control Loop
A control configuration is which an uproar is measured in output process variable of the system,
as a modification process variable is measured the value of a process variable is then compared
with the wanted value of the process variable and any essential action is taken. Feedback
control is considered as the simple control loops system. Its drawbacks lie in its operational
procedure. For example, if a convinced quantity is inflowing the process, then a monitor will
be there at the process to note its values. Any changes from the set point will be directed to the
final control element through the controller so that to regulate the incoming quantity rendering
to desired value (set point). But in fact, changes have already occurred and only corrective
action can be taken while using feedback control system. As compare to feed forward control
loop, this one is less expensive.

12.3.3 Ratio Control

A control loop in which, the regulatory element upholds a Pre-determined ratio of one variable
to another. Typically, this control loop is attached to such a system where two different systems
enter a vessel for response that may be of any kind. To uphold the stoichiometric quantities of
dissimilar streams, this loop is used so that to ensure proper process going on in the process
vessel.
12.3.4 Auctioneering Control Loop
This kind of control loop is normally used for a huge vessel where readings of a single variable
may be different at dissimilar locations. This type of control loop guarantees safe operation
because it employs all the interpretations of different locations simultaneously, and compares
them with the set point, then the controller sends suitable signal to last control element.
12.3.5 Split Range Loop
In this loop controller is predetermined with different values consistent to different actions to
be taken at different circumstances. The advantage of this loop is to maintain the proper
conditions and avoid abnormalities at very difference levels.

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12.4 Control Scheme on Heat Exchanger

Basic objective to use control loop on heat exchanger is to govern the temperature of process
gas and also eradicate the incoming disturbances. So that the whole system remnants in steady
state.

12.4.1 Control objective

• To control the outlet temperature of the process gas.
• To eradicate the external disturbances.

12.4.2 Manipulated variable:

• Flow rate of cooling water (utility stream).
• Flow rate of process gas (also possible).

12.4.3 Controller:
• Proportional integral controller.

12.4.4 Final control element:

• Pneumatic control valve.

12.5 Feedback Temperature Control Loop

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 REFERENCES

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