CHAPTER

ONE
INTRODUCT
ION

1
1.1Formula C8H8 Chemistry
Styrene is a certain organic chemical having the chemical formula C6H5CH=CH2.

Its chemical structure is made up of a group bonded onto a benzene ring. This
benzene ring makes styrene an aromatic compound.

Styrene is a clear, colorless liquid that is derived from petroleum and natural
gas by-products.

Other names for styrene can be styrol, vinyl benzene, phenylethene, or phenyl
ethylene.

Styrene helps create plastic materials used in thousands of remarkably strong,

flexible, and lightweight products, which represent a vital part of our health and
well-being. It's used in everything from food containers and packaging
materials to cars, boats, and computers.

Figure1.1 Chemical
structure of styrene

Styrene dissolves in some liquids, but dissolve only slightly in water , It is

2
soluble in alcohol , ether acetone ,and carbon disulphide ; It is incompatible
with oxidizers , catalysts for vinyl polymers ,peroxides ,strong acids .and
aluminum chloride .

Styrene is dangerous when exposed to flame heat or oxidation ; it reacts

violently with chlorosulfonic acid, oleum ,and alkali metal graphite , and reacts
vigorously with oxidizing materials, It may polymerize if contaminated or
subjected to heat , on decomposition , it emits acrid fumes, it usually contains
an inhibitor such as tert-butylcatechol .

1.1.1Occurrence, history, and use

Styrene is named after the styrax trees from whose sap (benzoic resin) it can be
extracted. Low levels of styrene occur naturally in plants as well as a variety of
foods such as fruits, vegetables, nuts, beverages, and meats. The production of
styrene in the United States increased dramatically during the 1940s, when it
was popularized as a feedstock for synthetic rubber.

The presence of the vinyl group allows styrene to polymerize. Commercially

significant products include polystyrene, ABS, styrene-butadiene (SBR) rubber,
styrene-butadiene latex, SIS (styrene-isoprene-styrene), S-EB-S (styrene-
ethylene/butylenes-styrene), styrene-divinyl benzene (S-DVB), and unsaturated
polyesters. These materials are used in rubber, plastic, insulation, fiberglass,
pipes, automobile and boat parts, food containers, and carpet backing.

1.1.2 Sources

Styrene is one of the most important monomers worldwide, and its polymers
and copolymers are used in an increasingly wide range of applications.
3
The major uses are in plastics, latex Paints and coatings, synthetic rubbers,
polyesters and styrene-alkyd coatings Among the top 50 chemicals worldwide,
styrene was twentieth in 1994 with production of 11 270 million pounds.
Styrene occurs naturally as a degradation product in cinnamic acid Containing
plants, e.g. balsamic trees, and as a by-product of fungal and microbial
metabolism.
Styrene has been detected in the atmosphere in many locations. Its presence in
air is principally due to emissions from industrial processes involving styrene
and its polymers and Copolymers. Other sources of styrene in the environment
include vehicle exhaust, cigarette smoke and other forms of combustion and
incineration of styrene polymers.
The concentration of styrene in urban air is relatively low compared with that
for aromatic hydrocarbons, such as toluene and xylene. This appears to be due
to the ready reactivity of Styrene with ozone to yield benzaldehyde and
peroxides, all of which are irritants; one of peroxide, peroxybenzyol nitrate, is a
potent eye irritant. Styrene is an active component of photochemical smog.
Some liberation of styrene may also take place from recently manufactured
plastic goods. While this may contribute to indoor levels of styrene, the effect
on total emissions to the environment is negligible.

1.1.3 Applications

Styrene monomer is a basic building block of the plastic industry. It is used

to make a host of downstream derivative products that go into millions of
consumer goods. Primary derivatives of styrene monomer, in order of
demand, include: polystyrene, expandable polystyrene (EPS) and
acrylonitrile- butadiene-styrene (ABS)/styrene-acrylonitrile (SAN) resins,
4
styrene butadiene (SB) latex, SB Rubber (SBR), unsaturated polyester resins
(UPR), specialty polymers, co-polymers and styrene thermoplastic
elastomers (TPE)
(see Figures 1.3 and 1.4).

Polystyrene is one of the easiest plastics to use to produce commodity

packages and consumer goods. It is primarily used in insulation, packaging,
appliances, furniture, toys and cassettes. It consumed 49 percent of the world
production of styrene monomer based on 2004 data.

Expandable polystyrene (EPS) beads are produced from styrene monomer

and non-CFC (chlorinated fluorocarbons) blowing agents. It is primarily used
in food packaging, insulation and cushion packaging. Resins of ABS/SAN
are used in construction materials, appliances, business machines and
transportation. Expandable polystyrene and ABS/SAN resins accounted for
30 percent of the world production based on 2004 data. Other applications
include paper and textile coatings and carpet backing (SB latex), production
of tires (SBR), construction and marine applications (UPR), adhesives and
polymer modification (TPEs), etc.

Polystyrene products are recyclable. In the past, polystyrene companies

routinely recycled plant scraps to make their manufacturing processes as
efficient as possible. More recently, with growing concerns about how it
disposes of its wastes, the polystyrene industry has started recycling post
consumer polystyrene packaging. Polystyrene is being recycled back into
packaging, as well as durable goods such as office supplies, house and garden
products, construction materials, video cassettes and other useful products.

5
1.2Production of Styrene

1.2.1Dehydrogenation of ethyl benzene

Ethyl benzene is dehydrogenated to styrene by the following reaction:

This is the desired selective reaction; however, various non-selective reactions

will occur. For example, a reactor effluent contains an average of 0.7%
benzene and 1.0% toluene.

The crude styrene, with an average composition of 37% styrene, 61% ethyl
benzene, 1.0% toluene, 0.7% benzene, and 0.3% tars, is passed through a pot
containing sulfur or some other polymerization inhibitor and is then fed into a
vacuum column system. The overhead from a primary fractionating column is
fractionated to separate the ethyl benzene, which is Recycled, from the
benzene and toluene, which are separated by distillation. The bottoms from a
primary fractionating column are distilled to obtain the pure styrene product .

6
The reactions for styrene production are as follows:

1
C6 H 5C2 H 5  C6 H 5C2 H 3  H2
2
ethylbenzene styrene hydrogen

3
C6 H 5C2 H 5  C6 H 6  C2 H 4
ethylbenzene benzene ethylene

4
C6 H 5C2 H 5  H2  C6 H 5CH 3  CH 4
ethylbenzene hydrogen toluene methane

1.2.2 Co-product with propylene oxide

7
 Ethyl benzene is oxidized to the hydro peroxide, which is then reacted with
propylene to yield the propylene oxide and a co-product, methyl phenyl
carbinol. The carbinol is then dehydrated to styrene . Expected impurities may
include propylbenzene, isopropyl benzene, and alpha-methyl styrene.

1.2.3 From pyrolysis gasoline

Figure 1.2 manufacture of styrene from a gasoline fraction

1.2.4 Dehydrates of 1-phenylethanol

An obsolete process for styrene production involved oxidation of ethyl benzene

to acetophenone and 2-phenylethanol, followed by hydrogenation of the
acetophenone to 1-phenylethanol, this dehydrates easily to styrene.

8
1.2.5 Oxy dehydrogenation of 4-vinylcyclohexene

Dow has proposed a route to styrene by oxy dehydrogenation of 4-

vinylcyclohexene prepared by butadiene dimerization. The dimerization is
performed in the gas phase at 100°C and 25 bar over a proprietary catalyst
consisting of copper loaded Y-zeolite.
The second step is oxy dehydrogenation of vinyl cyclohexene to styrene. This
reaction is catalyzed by mixed-metallic oxides in the vapor phase at about
400°C and 2.4 bar.
A variant of this process, developed by DSM, converts the vinylcyclohexene to
ethyl benzene, and the dehydrogenation can then be carried out in a
conventional plant. The DSM process employs liquid-phase butadiene
dimerization to 4-vinylcyclohexene catalyzed by iron dinitrosyl chloride–zinc
complex [Fe (NO2) Cl/Zn], while the dehydrogenation to ethyl benzene is
catalyzed by palladium on magnesium oxide. Final conversion of ethyl benzene
to styrene can be carried out with conventional dehydrogenation catalysts.

9
1.2.6 Production of styrene from toluene and methanol

Styrene can be produced from toluene and methanol, which are cheaper raw
materials than those in the conventional process. Historically, however, this
process has suffered from low selectivity due to competing decomposition of
methanol. Excellus Inc. claims to have developed this process with
commercially viable selectivity, at (400-425) °C and atmospheric pressure, by
forcing these components through a proprietary zeolitic catalyst. It is reported
that an approximately 9:1 mixture of styrene and ethyl benzene is obtained,
with a total styrene yield of over 60%.

1.2.7 Production of styrene via benzene and ethane

Another developing route to styrene is via benzene and ethane. This process is
being developed by SnamprogettiS.p.A. and Dow. Ethane, along with ethyl
benzene, is fed to a dehydrogenation reactor with a catalyst capable of
simultaneously producing styrene and ethylene. The dehydrogenation effluent
is cooled and separated and the ethylene stream is recycled to the alkylation
unit. The process attempts to overcome previous shortcomings in earlier
attempts to develop production of styrene from ethane and benzene, such as
inefficient recovery of aromatics, production of high levels of heavies and tars,
and inefficient separation of hydrogen and ethane. Development of the process
is on-going.

10
1.2.8 Dehydration of phenyl methylcarbino

The process is similar to the oxidation of cumene to cumene hydro peroxide

and isobutane to tert-butyl hydro peroxide.
Magnesium carbonate is added to adjust the pH to 7 to reduce the
decomposition of the hydro peroxide. Selectivity of about 65% is possible only
at a low conversion of 15–17%. Above that concentration, byproducts including
phenylmethylcarbinol and acetophenone increase appreciably. Meanwhile,
acetophenone can be converted to styrene by hydrogenation to
phenylmethylcarbinol and subsequent dehydration.

The epoxidation stage is also similar to the production of tert-butyl hydro

peroxide, a molybdenum naphthenate catalyst playing an important role.
However, this requires milder conditions of 100–130°C in the liquid phase
under ambient pressure. Selectivity of propylene to propylene oxide is about
91%. Byproducts include dimmers of propylene, whose formation can be
inhibited by antioxidants. The vapor phase dehydration of

11
phenylmethylcarbinol to styrene takes place over a catalyst at 200–280°C.
Titania and alumina are typical catalysts.

1.2.9 By oxidative dehydrogenation

This styrene process has not been commercialized, although Dow described an
improved catalyst in the mid-1990s (see note at the end of this chapter). A
catalyst with large ligands that suppresses 4-vinylcyclohexene formation is
nickel in combination with tries-O-phenyl phenyl phosphate. At 80°C and 1
bar, selectivity to 1, 5- cyclooctadiene is 96%. DSM has developed a related
approach to styrene via butadiene. Vinylcyclohexene is dehydrogenated in the
gas phase over a proprietary Pd/MgO catalyst to give ethyl benzene.
The ethyl benzene can then be converted to styrene by conventional techniques.

The Dow process for conversion of butadiene to styrene involves dimerization

of butadiene to vinylcyclohexene followed by an oxidative dehydrogenation of
the vinylcyclohexene to styrene. The dimerization is catalyzed by copper
loaded Y zeolite. The oxidative hydrogenation uses proprietary mixed-oxide
catalysts. A DSM process has three steps, the first being dimerization and the

12
second dehydrogenation to ethylbenzene followed by further dehydrogenation
to styrene. The first dehydrogenation uses a Pd/MgO catalyst. The ethyl
benzene–styrene conversion is conventional.

1.2.10 Styrene from toluene

Toluene is dehydrocoupled to stilbene followed by a metathesis reaction with

ethylene. The first step takes place at 600°C in the presence of a lead
magnesium aluminates catalyst and the second at 500°C with calcium oxide–
tungsten oxide catalyst on silica.

1.3 selective method

Adiabatic dehydrogenation process

1. Over 75% of all operating styrene plants carry out the dehydrogenation
reaction adiabatically in multiple reactors or reactor beds operated in
series.
2. Adiabatic reaction drops the temperature, so the outlet stream is reheated
prior to passage through the second reactor.
3. The reactors are run at the lowest pressure that is safe and practicable.
4. Some units operate under vacuum, while others operate at a low positive
pressure.
5. The reactor effluent is fed through an efficient heat recovery system to
minimize energy consumption, condensed, and separated into vent gas, a
crude styrene hydrocarbon stream, and a steam condensate stream.

13
 6. The practical size is not limitation on a reactor-exchanger than that in the
isothermal process.
7. By EB dehydrogenation, using reactor with adiabatic and one heated
stage.
8. By EB dehydrogenation, using reactor with two adiabatic stages.
9. are intended to resemble widely-licensed types of units for EB and
styrene manufacture. It is concluded that the competitive processes are
essentially equivalent economically.
10. require a somewhat lower investment.
11. looks slightly cheaper than the dehydrogenation routes, despite a
higher investment.
12. still undergoing process development, appears potentially very
attractive compared with any of the other styrene processes.
13. Highly selective reaction.
14. All carbon steel equipment. Because it we must add an inhibitor such as
TBC inhibitor to prevent corrosion and acceptable color for final
product.
15. Insignificant amounts of xylenes are produced, providing highest product
quality.
in these method we can used the following composition of catalyst : (62%
Fe2O3, 36% K2CO3, 2% Cr2O3)

For the following reasons :

1. Selectivity may reach to 95% based on ethyl benzene.

2. Minimizes production cost.
3. Minimizes plant downtime.
4. High yield.
5. Long catalyst run-length with excellent stability.

14
1.4 Physical properties

15
16
 Table 1.2 Worldwide supply and demand for styrene in 1998 (thousand tonnes)

Capacity Production Consumption

North 5 241
6 763 6 095
America
South 548
400 339
America
Western 4163
4 852 4 040
Europe
Eastern 411
1 176 366
Europe
275
Middle East 555 518
7155
Asia 7 294 6 503
119
Other 112 84
17 945 912
Total 21 152

17
 Use
North Western
Asia Other Total
America Europe
3 203
11 239
Polystyrene 2 649 4 409 978

Unsaturate 323
749
d polyester 220 161 45
resins
396
ABS/SAN 2 334
433 1 462 43
resins
Styrene– 410
1 116
butadiene 383 279 44
copolymer
263
SBR and 841
123 270 185
latexes
619
1 633
Other 355 574 85

Table1.3 Use patterns for styrene worldwide in 1998 (thousand tonnes)a

ABS, acrylonitrile–butadiene–styrene; SAN, styrene–acrylonitrile; SBR, styrene–

butadiene rubber a From Ring (1999)

18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
 Ethylbenzene+Toluene+Benzene

Vent gases
Toluene+Benzene

Feed

Waste water

Air ng

Figure (1.17) flow sheet material balance

33
 CHAPTER
TWO
MATERIAL
BALANCE

34
2.1Basic calculations

Main Reaction:

↔ +

106 104 2 MWT

Operating time =8,000 hour =330 day

Product=100,000 ton/year*1 year/8,000 hr.*1000 =12,500

Hence;

12,500/104 =120.1923

Yield=

Yield=0.9

Then:

EB.reacted= =133.547

Fresh feed =14,155.982

= = 205.4569

EB. Unreacted =Input- reacted

35
= 205.4569- 133.547

= 71.9099

=7622.4494

EB. In Recycle stream =7622.4494

Fresh feed composition

EB. Fresh feed = 99 wt. %

Tol. Fresh feed = 0.5 wt. %

B fresh feed = 0.5 wt. %

We can calculate the quality of B-Z &Tol. By:

B =71.49485859

= Tol. = 71.49485859

Recycle stream composition

EB. = 99 wt. %

Tol. = 0.5 wt. %

B = 0.5 wt. %

B=38.4972

= Tol. = 38.4972

36
Side Reaction:

+ +

106 2 92 16 MWT

Selectivity =

Selectivity of tol. = 0.06 at 900 K

Tol. (Out) = 7.2115

= 663.4614

For CH4 = 7.2115

= 115.384
Side reaction:

106 78 28

Selectivity for B = 0.0511

0.0511 =

B (out) = 6.1432 = 479.1696

For = 6.1432 = 172.0096

Leaving reactor = produce from mean reaction – reacted in side

reaction

37
 = 120.1923 -7.2115 =112.9808 =225.9616

2.1.1Checking Overall the Plant

INPUT= (133.547* 106) + (0.7771* 92) + (0.9166 * 78)

= 14298.97

OUTPUT = (120.1923* 104) + (112.9808 *2) + (7.9886* 92)

+ (7.2115*16)+ (7.0598*78)+(6.1432*28) = 14298.97

2.2Feed input to reactor

(Fresh+Recycle) =14298.97+7622.4494+38.4972*2

= 21998.4138

Amount of steam input to reactor

The ratio of steam to ethyl benzene input to reactor range between (6-12)

=9

Amount of steam =9*205.4569= 196005.8826

F1 = (input to reactor)

= 21998.4138 +196005.8826

= 218004.2964

Amount of out reactor

St =120.1923*104=12500

EB=9099*106 =7622.4494

Tol =in +product= out

Out =0.7771+7.2115+0.41844
38
 =8.40704 =773.44768

B =In +product= out

Out= 0.9166+0.49355+6.1432

=7.55335

=589.1613

=7.2115*16=115.384

=6.1432*28=172.0096

Steam=196005.8826

=112.9808*2=225.9616

F1=218004.2964kg/hr
EB=9.9899%
Tol=0.05045%
BZ=0.05045%
Steam=89.9092%

Reactor F2=218004.2964kg/hr
St=5.73383%
EB=3.49646%
Tol=0.35478%
Bz=0.27025%
CH4=0.052927%
C2H4=0.078901%
H2=0.10365%
39 Steam=89.9092%
2.3Material balance on separator

Liquid vapour equilibrium calculations:-

F = 120.1923 + 112.9808 +71.9099 +8.40704+7.55335+7.2115 + 6.1432 +

10889.2157

= 11223.61379

Mole fractions of F

Z = 0.010708

𝑍 = 6.72987*10

Z = 0.010066

Z = 5.47345*10

𝑍 = 7.49049 *10

Z = 6.40701*10

Z = 6.42529*10

Z = 0.970205

K- value at 75 :C and 14.507 psig:-

In separator, light gases ( + ) removed as Top product with small amount

of toluene and Benzene. To find amount of toluene and benzene we need K-
Values for these component.

k=

40
 Where: -

P* is the vapour pressure (psig)

P is the total pressure (psig)

Value of k:

02

0 8596

0 472098

11223 61379
0 472098

7624 23003

11223 61379 7624 23003

3599 38376

Material balance on Tol.

11223 61379 7 49749 10 7624 23003 0 2 3599 3876

1 6406439 10

41
 02

3 2812879 10

2 5017294

230 159105

543 288575

Material balance on B.Z

11223 61379 6 72987 10

7624 23003 0 8596 3599 3876

7 4393927 10

6 39490199 10

𝑍 4 8756203

𝑍 380 298389

𝑍 208 8629104

Material balance on C2H4 (from the top)

172 0096

42
Material balance on CH4 (from the top)

115 384

Material balance on H2 (from the top)

225 9616

Material balance on steam (from the bottom)

196005 882

Material balance on styrene (From side stream)

12500

Material balance on EB. (From side stream)

7622 4494

checking on separator

218004 2964

172.0096+115.384+225.9616+230.159105+380.298389

43
1123 812694

196005 8826

12500 7622 4494 543 288575 208 8629104

20874 60089

218004 2964

218004 2964

F4=1123.8126kg/hr
C2H4=15.30589%
CH4=10.26719%
H2=20.1067%
Tol=20.4802%
Bz=33.84%

F3=218004.2964kg/hr F6=20874.60089kg/hr
St=5.73383% St=59.8813%
EB=3.49646% EB=36.5154%
Tol=0.35478% Tol=2.6026%
Bz=0.27025% Bz=1.0056%
CH4=0.052927%
C2H4=0.078901% Separator
H2=0.10365% F5=196005.8826kg/hr
Steam=89.9092% Water=100%

44
 2.4material balance on distillation section

Tol_in stream (9)

99
05

99 12500
05

9 63 1313

B.Z in stream(9)

99
05 Z

99 12500
05 Z

Z 9 63 1313

9 0 99 12500

9 12375

2 9

38 4972 63 1313

101 6285 2

Z 2 Z Z 9

45
38 4972 63 1313

101 6285 Z 2

7
1
8

7 543 288575 101 6285

7 441 660075

Z 7
Z 1
8

Z 7 208 8629104 101 6285

107 2344104

Z 7 441 660075 107 2344104

548 89448

7 125

12375 101 6285 101 6285 7622 4494

20200 7064

46
 F7=673.8944kg/hr
Tol=65.5384%
Bz=15.9126%
St=18.5488%
R=7699.4438kg/hr
EB=99%
Tol=0.5%
F6=20874.60089kg/hr Bz=0.5%
St=59.8813%
EB=36.5154%
Tol=2.6026%
Bz=1.0056%

F8=20200.7064kg/hr
St=61.2602%
Bz=0.50309%
Tol=0.50309%
EB=37.7335%
F9=12501.2626kg/hr
St=98.99%
Bz=0.5049%
Tol=0.5049%

47
 CHAPTER
THREE
ENERGEY
BALANCE

48
 3.1Energy Balance on the mixing point 1

Temperature of the fresh feed = 303 K

Temperature of the recycle stream = Temperature of top section of

second distillation = 396.75 K

1 2

1 R 2

∑ ( ) ∑ ( ) ∑ ( )

1 ∑ ( )

Eth. Tol BZ

Eth ( )

133 547 913 101

121942 0004

Tol ( )

0 7771 785 07

610 0788

BZ ( )

0 916579 675 7835 619 4089

1 123171 4881

49
 R ∑ ( )

Eth. 𝑍

Eth ( )

71 9099 21506 9726

1546564 251

To l ( )

0 41845 18603 33514

7784 5655

BZ ( )

0 49355 16002 7299

7898 1473

R 1562246 964

1 R 1685418 452

2=∑

Eth Tol BZ

0 035526 12 4488 35372 03518 10375816 01

2 06721 10 0 0724367796 205 8206

60405 1039

3 17317 10 0 1911 219 45275 56852 35867

0 036050038 12 71233 35797 3085 10493073 47

50
0 0 036050038 12 71233 35797 3085 12178491 92

By using MATLAB

T2=341.51 k

3.2Energy Balance on the first heat exchanger:

QMX =∑ ∫ ∑ ∑ ∫

QEth. = ∫ ∫

2783095 03 7311800 157 1197285 553

11292180 74

QTol = ∫ ∫

13934 7441 39691 7955 5768 4773

59395 0169

QBZ = ∫ Z ∫

2335 8302 43404 2881 14367 8187

60107 93701

HX 1141683 69

steam 1141183 69

Let steam enter heat exchanger at 220 and out at 110

51
1 101 325 220 2914 904

2 101 325 110 2696 229

steam
̇

M=

M = 52185.589

3.3Energy Balance on the second heat exchanger:

QHX =∑ ∫ ∑ ∑ ∫

QEth. = ∫ ∫

1197285 553 7311800 157 537734

11491857 37

QTol = ∫ ∫

10043 9775 39691 7955 29794 72823

59442 5462

QBZ = ∫ Z ∫

13848 8995 43404 2881 32836 2964

62391 6861

HX 11613691 6

steam 11613691 6

52
 steam
̇

1 101 325 300 3074 443

2 101 325 180 2835 705

M=

M 48646 17

3.4Energy Balance on the mixing point

4 5

4 𝑍

QEth. = ∫ ∫

4444854 575 7311800 157 5377342 699

17133997 43

QTol = ∫ ∫

16923 8238 39691 7955 29794 7282

86410 3475

QBZ = ∫ Z ∫

10809 7862 43404 2881 32836 2975

87050 3719

4 17307458 15

5 5 𝑍

53
QEth. = ∫ ∫

4444994 491 7311800 157 24958103 98

36714898 62

QTol = ∫ ∫

16923 8238 39691 7955 124130 9896

180746 6089

QBZ = ∫ Z ∫

10809 7862 4304 2881 184219 7198

238433 7942

∫ ∫ t

60483638 17 443005962 3 212702922 8

716192523 3

5 753326602 3

heat of steam = ∫ ∫

60483638 17 443005962 3 + ∫

∫ 10889 2157[(32 243 9 619 10

3 518 10 8 99 10 ) 12325 632 ]

54
 351100 9818 10 47433 0 0383
9 7894 10 134216465 5

steam

17307458 15 753326602 3 736019144 2

736019144 2

0 351100 9818 10 47433 0 0383 9 7894

10 366746009 2

By using MATLAB

947 46

3.5 Energy balance around fired heater

140 2733 026

674 31 500 3869 835

Where:

̇ : Specific enthalpy change (KJ/Kg)

196005 8826 3869 835 2733 026 222821408

55
 3.6 Energy balance around reactor

Therefore:

6 5

5 753326602 3

̇ 117650

̇ 105500

̇ 54640

∑( ̇ )

117650 120 1923 105500 7 5533 54640 8 40704

14478136 58

6 753326602 3 14478136 58 738848465 7

6 6

The enthalpy of each component in stream 6 can be calculated as show

below:

56
 ( ) ∫

Where :

( )

( )

1849673 289 3099 2447 25 4255 0 01153

2 3385 10

Enthalpy of Styrene

3185441 358 3395 192 37 012 0 01611 2 9853

10

57
Enthalpy of Toluene

201031 8662 204 7534 2 1541 7 7484 10

1 0321 10

Enthalpy of Benzene

188734 1268 256 1852 1 7914 7 596 10

1 34639 10

Enthalpy of Steam

368330789 9 350815 6844 10 4645 0 05744

9 781238 10
Enthalpy of the can be calculated as below:

∫ ∑

58701 1473 138 8285 0 1879 2 8783 10

2 0408 10

45409 5236 23 381 0 4809 1 70944 10

2 69548 10

948809 7698 3066 6378 0 5238 5 20088 10

2 159373 10

58
 6
372702750 1 347089 1564 78 0401
0 027603 3 9971049 10

0 366145717 6 347089 1564 78 0401 0 027603

3 9971049 10

By using MATLAB

849 75

3.7 Energy balance around third heat exchanger

∫ ∑

71 9099 41422 1434 2978662 19

8 40704 34386 2359 289086 4611

120 1923 37996 5977 4566898 473

7 5533 27810 6255 210061 998

6 1432 12464 7067 76573 1862

112 9808 4440 1876 501655 9472

59
 7 2115 9229 7694 66560 4827

10889 2157 5755 7447 62675545 83

71365044 57

3.8 Energy Balance around fourth heat exchanger

∫ ∑

71 9099 79767 0008 5736037 051

8 40704 29926 9078 251596 711

120 1923 33498 3194 4566898 473

7 5533 24263 0369 183265 9966

6 1432 10985 5852 76573 1862

112 9808 4411 7705 498445 3605

7 2115 8056 8951 58102 2997

10889 2157 5499 9564 59890212 64

70711386 77

60
3.9 Energy Balance around fifth heat exchanger

∫ ∑

71 9099 26136 2194 1879452 924

8 40704 21371 0394 179667 1831

120 1923 24273 6436 2917505 059

7 5533 17287 0939 130574 6069

6 1432 8061 8501 49525 5575

7 2115 5984 8103 43159 4595

10889 2157 4579 3519 59890212 64

55495198 04

3.10 Energy Balance around sixth heat exchanger

For C8H10 (v) → C8H10(l)

61
 ∫ ∫

133355 7518 2559129 521 1335905 616 4028390 889

For styrene C8H8(v) → C8H8(l)

∫ ∫

36862 4871 4428365 101 1298831 592 5764059 18

For Toluene C7H8 (v) → C7H8 (l)

∫ ∫

42389 3154 279122 135 77950 3766 399461 827

For Benzene C6H6 (v) → C6H6 (l)

∫ ∫

54443 9212 234008 7873 8266 8208 296719 5293

For water

∫ ∫

62
 17462989 48 443005962 3 19940024 71
480408976 5

For CH4, C2H4, H2

∫ ∑ ∫ ∑

279375 2739

491176983 2

140 2733 026

674 31 500 3869 835

Where:

̇ : Specific enthalpy change (KJ/Kg)

196005 8826 3869 835 2733 026 222821408

3.11Energy balance around knockout drum separator

∫ ∑

63
 ∫ ∑

42422805 99

191104 6581

42613910 65

40543612 64

∫ ∑

1825196 028

245101 9801

3.12Energy Balance on the seventh heat exchanger

412 69 384 15

64
 20874 60089 2 4169 412 69 348 15

3256179 592

3.13Energy Balance around first Distillation column

Mole fraction:

Component

Ethyl
71.9098 0.3582 ------ -------- 71.9099 0.3719
Benzene
Benzene 2.6912 0.013409 1.3748 0.18636 1.3029 6.739*10

Toluene 5.9053 0.029531 4.8006 0.65072 1.1096 5.748*10

Styrene 120.1923 0.59886 1.2019 0.16293 118.9903 0.6155
Total Summation 200.6986 1 7.3773 1 193.314 1

For calculate :

The feed is at boiling point so,

Component Boiling point (K)

Ethyl Benzene 409.25
Benzene 353.25
Toluene 383.75
Styrene 418.25

65
*So the temperature at feed point is ( )

=∑

= (0.4134*409.25) + (0.01193*353.25) + (002607*383.75) + (0.5306*418.25)

410.918 k

*So from Antoine-equation can find the partial pressure and after that can find
the pressure at the feed point.

*The constant value of Antoine-equation:

Component A B C
Ethyl Benzene 16.0195 3272.47 -59.95
Benzene 15.9008 2788.51 -52.36
Toluene 16.0137 3096.52 -53.67
Styrene 16.0193 3328.57 -63.72

Where p (mmHg) and T (K)

So,

847 43

652 64

3505 3

1617 72

For calculate :
66
 847 43
1 506
562 547

3505 3
6 231
562 547

1617 72
2 875
562 547

652 64
1 16
562 547

*Pressure at the feed point is ( )

0 4134 847 43 ) + (0.01193*3505 3 ) + (0.02607*1617 72 ) +

(0.5306*652 64

795 8642

0 4134 2.581) + (0.01193*2.285) + (0.02607*2.455) +

(0.5306*2.2846)

2 416

20874 60089 2 416 412 69 29815

5776599 915

67
Calculation of :

For calculate temperature in the top section

First trial:

Assume that

412 69

So,

847 43

652 64

3505 3

1617 72

So total pressure is = 1812.23 mmHg

And is not equal to the operational pressure

Second trial:

395

519.25

392.17

2350.75

68
 1034.6

So, total pressure is =1175.19 mmHg

And is not equal to the operational pressure

Third trial:

383K

361 25

268.82

1749.57

743.38

So, total pressure is =853 mmHg

Fourth trial:

360

69
 166.182

931.31

366.96

119.672

So, total pressure is =431.83 mmHg

Fifth trial:

370
236.23

172.7

1238.87

505.12

So, total pressure is =587.69 mmHg

Sixth trial:

368 55

70
 224.8

1189.99

164.3

482.86

So, total pressure is =562.548 mmHg

T=368.55 K

As a same rule find the

0 18635 2 285 0 65072 2 455 0 16293 2 2846

2 3955

673 8944 2 3955 368 55 298 15

113647 7081

Calculation of QB:

Assume that =

First trial:

, =412.69 K

=847.43 mmHg

71
 =3505.3 mmHg

=652.64 mmHg

=1617.72 mmHg

So, total pressure is 749.78 mmHg

Second trial:

=409 K

=768.26 mmHg

=3235.57 mmHg

=589.39 mmHg

=1479.12 mmHg

So, total pressure is 678.79 mmHg

Third trial:

TB, Assume=405 K

=689.146 mmHg

=2960.975 mmHg

=526.42 mmHg

=1339.42 mmHg

72
So, total pressure is 607.95mmHg

Fourth trial:

TB, Assume=402.2 K

=637.69 mmHg

=2779.38 mmHg

=485.61 mmHg

=1247.85 mmHg

So, total pressure is 562.549 mmHg

=∑ *

= (0.3719*2.581) + (6.739*10 *2.285) + (5.748*10 *2.455) +

(0.6155*2.2846) =2.3955

QB =m* *

=20200.7064*2.3955*(402.2-298.15)

=5035061.926

Distillation temperature:

̅ ∑ ⁄

73
The most plentiful component is toluene, because 0 65072

Component

Ethyl Benzene
0.5238 --------

Styrene 0.4034 0.0657

Benzene 2.1673 0.4038
Toluene 1 0.65072
Total Summation 4.0945 1.12022

̅ 1 12022

= 66.951 = 502.174 mmHg

3096 52
502 174 16 0137
53 67

T=369.81 K

369 81

Over head vapour temperature:

The most plentiful component is toluene, because

0 65072

74
 Component ⁄

Ethyl Benzene 0
Styrene 0.4038
Benzene 0.0859
Toluene 0.65072
Total Summation 1.14042

∑
⁄

75 1 14042 85 5315 641 539

3096 52
641 539 16 0137
53 67

377 91

For calculate :

377 91

369 81

For calculate for gas mixer:

Component a *b* *c* *d*

Ethyl Benzene
-------- --------- -------- --------
Styrene -18.3815 40.0765 -2.6178 64.6509
Benzene -6.3204 8.8396 -0.5622 13.2869
Toluene -40.5499 82.2628 -4.9792 109.8953

75
 ∫ 40 5499 82 2628 10 4 9792 10

109 8953 10

1598 941 ⁄

∑Xi=1

∑ ∑ 1
1 1

1
1 1 1 1 1 1

0 3582 0 013409 0 029531

1 1 1 506 1 1 6 231 1 1 2 875
0 029531 0 59886
1
1 1 2 875 1 1 1 16

*By trial and error find the ѱ

Ѱ=0.05

0 05
200 6986

10 0349

L=F-V

76
L=200.6986-10.0349

L=190.6636

190 6636
25
7 3773

10 0349 1598 941

1604 991

For Calculate and in re-boiler:

In the re-boiler:

̅ ∑ ⁄

*The most plentiful component is Styrene, because 0 6155

Component

Ethyl Benzene
1.2982 0.4828
Styrene 1 0.6155
Toluene 2.875 0.01652
Benzene 5.3715 1.15092
Total summation 10.5447 1.15092

̅ 1 15092
75
65 1652 488 7796
1 15092

77
 3328 57
488 7796 16 0193
63 72
402 42

For calculate :

The most plentiful component is Styrene, because

0 6155

Component ⁄

Ethyl Benzene 0.2864

Styrene 0.6155
Toluene 1.9993*10
Benzene 1.2545*10
Total Summation 0.9051

∑
⁄

75 0 9051 67 8825 509 1605

3328 57
509 1605 16 0193
63 72

403 83

Cpmix =∑Cpi *xi

=2.3955

78
 For calculate :

402 42

403 83

19922 0311 2 3955 403 83 402 42

67289 7481

3.14 Energy Balance on the second Distillation

By using a modified form of Kopp’s law, which is given by Werner (1941)
(volume 6, page321, by R.K.Sinnott) Can be finding the heat capacity of liquid:

Component of liquid
Ethyl Benzene 2.581
Benzene 2.285
Toluene 2.455
Styrene 2.2846
Total Summation 9.6056

Mole fraction:

Component
Ethyl Benzene
71.9099 0.3719 71.9099 0.9874 ------ ------
Benzene 1.3029 6.739*10 0.4935 6.8545*10 0.8092 6.716*10
Toluene 1.1096 5.748*10 0.4184 5.7455*10 0.686 5.684*10
Styrene 118.9903 0.6155 ---------- ------ 118.99 0.9876
Total Summation 193.3127 1.00 72.2818 1.00 120.48 1.00

79
 ∑

For calculate :

=403.83 K

So from Antoine-equation can find the partial pressure and after that can find
the pressure at the feed point.

Where p (mmHg) and T (K)

So,

667.264

509.0542

2884.0497

1300.55

For calculate

1.1867

5.1267

80
 2.3118

0.9049

Pressure at the feed point is ( )

588.38

2 3955

20200 7064 2 3955 403 83 298 15

5113938 918

Calculation of :

For calculate temperature in the top section

First trial:

Assume that

403 83

So,
667 264

509 0542

2884 0497

1300.55

So, total pressure is = 2077.81

And is not equal to the operational pressure.

81
Second trial:

396
534 5659

2407 0909

1062.3896

404 2102mmHg

So, total pressure is = 550.43 mmHg

So,

Third trial:

396 75

546 2846

2450 0065

1082.88

413 432

So, total pressure is = 562.547 mmHg

So,

T=396.75 k
82
As a same rule find the

Component
Ethyl Benzene 71.9099 0.9874

Styrene ------------ ------------

Benzene 0.4935 6.8545*10
Toluene 0.4184 5.7455*10
Total Summation 72.2818 1

2 5782

7699 4438 2 5782 396 75 298 15

1957279 612

Calculation of

First trial:

Assume that

403 83

667 264

509 0542

2884.0497

83
 1300 55

So that the total pressure is = 529.5035 mmHg

So,

Second trial:

405
689 1467

2960 975

526.4235

1339 4201

Total pressure is = 547.395 mmHg

So,

Third trial:

405 97
707 3278

3024 555

84
 540.8706

1371 6369

So that the total pressure is = 562.547 mmHg

As a same rule find the

Component
Ethyl Benzene
--------- ---------
Styrene 118.99 0.9876
Benzene 0.8092 6..716*10
Toluene 0.686 5.684*10
Total Summation 120.48 1.00

2 2832

12501 2626 2 2832 405 97 298 15

3077493 62

Distillate temperature:

̅ ∑ ⁄

85
 ̅
*The most plentiful component is Ethyl Benzene , because
0 9874

Component

Ethyl Benzene
1 0.9874
Benzene 4.3222 0.02962
Toluene 1.94907 0.01119
Total Summation 7.27127 1.02821

̅ 1.028
75
72 9422 547 11
1 02821
389 8

Over head vapour temperature:

*The most plentiful component is Ethyl Benzene ,because

0 9874

Component ⁄

Ethyl Benzene 0.9874

Benzene 1.5858*10
Toluene 2.9478*10
Styrene -------------
Total Summation 0.9919

86
 ∑
⁄

75 0 9919 74 3925 557 989

3272 47
557 989 16 0195
57 95

397 486

For calculate :

397 486

389 8

*For calculate for gas condition

Component *a *c* *d*

*b*
Ethyl Benzene
-42.5559 69.8239 -4.7503 128.44
Benzene -0.2324 0.3251 -0.0206 0.4887
Toluene -1399 0.2944 -0.0158 0.2821
Total Summation -24.9282 70.4434 -4.7867 129.2108

∫ 24 2982 70 4434 10 4 7867 10

129 210 10

1433 885 ⁄

∑Xi=1
87
 1
1 1 1 1 1 1

0 3719 6 739 10 5 748 10

1 1 1 1861 1 1 5 1267 1 1 2 3118
0 6155
1
1 1 0 9049

By trial and error find the ѱ

Ѱ=0.08

0 08
193 3127

15 465

L=F-V

L=193.3127-15.465

L=177.8476

177 8476
2 46
72 2818

15 465 -1433.885

22175

For Calculate and in re-boiler

In the re-boiler

̅ ∑ ⁄

88
 ̅

*The most plentiful component is Styrene, because 0 9876

Component

Toluene 2.5547 0.01452

Benzene 5.665 0.03804
Styrene 1 0.9876
Total Summation 9.2201 1.04016

̅ 1.04016

75
72 1042 540 82
1 04016

3328 57
540 8265 16 0193
63 72

405 94

For calculate

*The most plentiful component is Ethyl benzene, because

0 987614

Component ⁄

Benzene 1.0089*10
Toluene 2.2249*10
Styrene 0.9876
Total Summation 0.9908

89
 ∑
⁄

75 0 9908 74 3125 557 389

3328 57
557 389 16 0193
63 72
407 01

For calculate :

405 94

407 01

=18439.092*2.2832(407.01-405.94)

=45047.1458

3.15 Energy Balance around Toluene pump

=75 Kpa

=101.325 Kpa

90
M=673.89

Basis 1 hour

M=673.89 Kg

∑ At 369.81 K

= (0.18639*797.05) + (0.65072*794.31) + (0.16293*838.4)

= 802.004

= 0 84

=V *(

=0.84*(101.325-75)

=22.113 KJ

= = =31.59 KJ

=31.59=∫

31.59=5.97*10 -0.2999 +487.2238 -182260.802

=394.65 K

3.16 Energy Balance around Styrene pump

=75 Kpa

=101.325 Kpa

M=12501.2626

91
Basis 1 hour

M=12501.2626 Kg

∑ At 407.01 K

= (5.716*10 *572.7) + (5.684*10 *754.104) + (0.9876*803.823)

= 801.41

= 15 599

=V *(

=15.599*(101.325-75)

=410.65 KJ

= = =586.633 KJ

=∫

586.633=5.97*10 -0.2999 +487.2238 -182260.802

=408.08 K

3.17 Energy Balance around Waste Water pump

=99.994Kpa

=101.325 Kpa

M=196005.8826

92
Basis 1 hour

M=196005.8826 Kg

∑ At 348.15 K

= 199 9305

=V *(

=199.9305*(101.325-99.994)

=266.1075 KJ

= = =380.153 KJ

=∫

380.1536 = 0.01625 +84.968 27611.97

=349.2 K

93
 389.8 k Ethylbenzene+Toluene+Benzene

849.75 k
348 k
Vent gases 377.91 k 369.81 k
394.65 k
Toluene+Benzene

369.81 k

348 k 397.486 k 389.8 k

303 k 348 k
Feed 903 k 403.83 k

402.2 k

407.01 k

947.46 k 408.08 k
styrene

405.94 k

349.2 k Waste water

348 k

Air ng

Figure (1.2) flow sheet energy balance

94
 CHAPTER
FOUR
EQUIPMENT
DESIGN
95
4.1 Reactor design

Packed bed reactor

8 10 8 8 2

35500
8 44 10

Where:

1 987

96
 0

10889 2157
81 5384
133 547

82 5384

1 1
82 5384 82 5384

1
90
82 5384

35500 1
8 44 10 ( ) ( 90)
82 5384

For adiabatic operation :

1
298 944 329 503
82 5384 82 5384

29 885 39 939
82 5384 82 5384

43 0798

0 65

43 2126

97
 43 0798 43 2126
43 1462
2

903 2726 7754 ( )

82 5384

35500
8 44 10 ( )
1 987 *903 2726 7754 ( )+
82 5384
1
( 90)
82 5384

35500
7 596 10 ( )
1 987 *903 2726 7754 ( )+
82 5384
1
( )
82 5384

∫ (5.19 chemical reaction engineering by Octave)

∫
( ) ( )

Can be solved numerically by Trapezoidal rule

35500 1
( )
1 98 903 2726 7754 ( ) 82 5384
82 5384

∫ 2( )
2

3 230758946 10

3 864571965 10

98
 4 682174784 10

5 764859987 10

7 2483875 10

9 377483797 10

1 264209401 10

1 500659986 10

0 , 0 65 , 7

0 65 0
3 230758946 10 2 3 864571965 10
2 7
4 682174784 10 5 764859987 10 7 2483875
10 9 377483797 10 1 264209401 10
1 500659986 10

4 893409063 10

4 893409063 10 133 547

8 6032
7 596 10

8 6032 3
4

1 54

4 62

99
Where :

For packed bed reactor volume and catalyst weight are related through the
equation:

1 (4.20 chemical engineering by Fugler)

Where:

W: weight of catalyst (kg)

e: porosity

v: volume of reactor ( )

1 05 8 6032 7019 30192 9304

30192 9304
4 3016
7019

Where:

1 54
4 3016
4
100
 2 31

2 8

4 3 6
4
3

Where:

6
750
8 10

Where:

8 314

101
 0 018514 106 1 07725 10 92
1 27058 10 78 0 9812 18

19 644

2400 19 644
6 2797
8 314 903

218004 2964
34715 718 9 62
6 2797

0 5 4 3016
0 23
9 62

Where :

0 5 2 31
5 02
0 23

1
1

Where:

35

102
 ∑

174 8426 10 0 018514

206 9632 10 1 07725 10
224 65 10 1 27058 10 337 3513 10
0 9812

3 3429 10

1 05
5 02
35 1 05 750 3 3429 10 2 31

30527 4

30 52 0 3052

Nozzles

293

Where:

293 60 55 6 2797

1306 62 1 306

103
4.2 Heat Exchanger Design

The heat exchanger which is used as cooler to cool the mixture of gases from
reactor column from 276.6 to 146.6 by using steam, gases is corrosive
and high tem. so he will be on tube side.

Operating Condition:

Temperature of a hot gases input 276 6

Temperature of a cold gases output 146 6

Temperature of a steam input 110

Temperature of a steam output 180

Step 1: Specifications:

The specification is given:

218004 2964 of gases is cooled by exchange with steam (single phase)

.The gases pressure is 2300 ,water pressure is2400 .

Permissible pressure drop 950 .

Fouling factors: gases is 5000 , for steam is 8000

The mean temperature of gases 211 6

The physical properties of gases at mean temperature:

1 981

1 657 10

104
Where:

19 422 2300
11 0842
8 314 484 75

The mean temperature of steam 145

The physical properties of steam at mean temperature:

1 9139

139 7277 10

18 2400
12
8 314 418 15

Energy balance on exchanger:

105
218004 2964
1 9581 276 6 146 6 1 9581 180 110
3600

115 Where:

15414 9

Step 2: Overall coefficient:

For exchanger of this type the overall coefficient will be take 600

Step 3: Exchanger type and dimensions:

We use shell and tube heat exchanger, and start with one shell pass and two

tube passes.

Mean Temperature Difference :

276 6 180 146 6 110

61 82
276 6 180
146 6 110

276 6 146 6
1 76
118 110

180 110
0 41
276 6 110

From fig (Sinnott et al., 2005), 0 76

106
 0 76 61 82 47 57

Step 4: Heat transfer area:

15414 10
540
600 47 57

Step 5: Layout and Tubs size:

Using split-ring floating head exchanger.

As the fluid is corrosive stainless steel is used.

Use 19 mm outside diameter, 15 mm inside diameter, 4.88 m long tube, on

triangular pitch.

4 88 4 88 2 0 025 4 83

19 10 4 83 0 2881

540
1874
0 2881

1874
2 937
2

107
 15 10 1 76625 10
4

937 1 76625 10 0 1654

218004 2964
5 463
3600 11 0842

5 463
33
0 1654

Step 7: Bundle and shell diameter

2 0 249 2 207

1874
19 1084 53
0 249

For a split – ring floating head exchanger the typical shell clearance

Is 72 mm, so the shell inside diameter (Sinnott et al., 2005).

1084 53 72 1156 53

Step 8: Tube side heat transfer coefficient:

11 0842 33 15 10
33112
1 657 10

1 657 10 1 9581 1000

8 77
0 03698

( )

108
 4 83
322
15 10

3 099 10

0 03698
3 099 10 33112 8 77 518
15 10

This is clearly too low if is to be 600 the tube-side velocity did look
low, so increase the number of tube passes to 4 , This will halve the cross-
sectional area in each pass and double velocity .

2 33 66

2 33112 66224

3 9 10

0 03698
3 9 10 66224 8 77 1303
15 10

Step 9: Shell side heat transfer coefficient:

4 0 175 2 285

1874
19 1102 33
0 175

1102 33 74 1176 33

1 25 1 25 19 23 75

109
 23 75 19
1176 33 529 34 10 0 1245
23 75

115
9 5833
12

9 5833
76 9
0 1245

11 11
( 0 917 ) 23 75 0 917 19
19

13 5

12 76 9 13 5 10
89157
139 7277 10

1 6 10

0 288
1 601 10 89157 9 28 6351 9
13 5 10

Step 10: Overall coefficients.

1 1 1
2

Where :

50

19
1 1 1 0 019 19 19
15
6351 9 8000 2 50 15 1303 15 5000

110
 643 99

This is above the initial estimate of 600 which may be acceptable.

Step 11: Pressure drop:

Tube side:

From fig. (Sinnott et al., 2005).

3 10

[8 2 5]
2

4 83 11 084 66
4 [8 3 10 2 5] 987 6
15 10 2

Shell side:

From fig. (Sinnott et al., 2005).

2 3 10

8 ( ) ( )
2

4 83 1176 23 12 76 6
8 2 3 10 ( ) ( )
529 10 13 5 2
5153 19

Could be reduced by increasing the baffle pitch .Doubling the pitch halves the
shell side velocity ,which reduces the pressure drop by factor of approximately

5153 19 1
323 07
4 2
111
This will reduce the shell side heat transfer coefficient by a factor of

where

6351 9 05 3648 2085

This gives an overall coefficient of 598 9925 .

Step 12: Input and Output Nozzles:

Diameter of nozzle is given in equation below

293

Nozzle for Input Hot gases

293 60 55 11 084 1000 1

Nozzle for output steam

293 115 12 1400 14

The vessel support used for the heat exchanger is two saddles.

112
 CHAPTER
FIVE
PLANT
LAYUOT&
TREATMENT
113
5.1 plant layout
The laying out of a plant is still an art rather than a science. It involves the
placing of equipment so that the following are minimized:

1- Damage to persons and property in case of a tire or explosion.

2- Maintenance costs.

3- The number of people required to operate the plant.

4- Other operating costs.

5- Construction costs.0

6- The cost of the planned future revision or expansion.

All of these goals cannot be met. For example, to reduce potential losses in case
of fire, the plant should be spread out, but this would also result in higher
pumping costs, and might increase manpower needs. The engineer must decide
within the guidelines set by his company which of the aforementioned items are
most important (William)

5.1.1: Site Considerations

The location of the plant can have a crucial effect on the profitability of a
project, and the scope for future expansion. Many factors must be considered
when selecting a suitable site, the principle factors to consider are:

1-Marketing area:

For materials that are produced in bulk quantities; such as cement, mineral
acids, and fertilizers, where the cost of the product per tone is relatively low
and the cost of transport a significant fraction of the sales price, the plant
should be located close to the primary market. This consideration will be less
important for low volume production, high-priced products; such as
pharmaceuticals.

Raw materials

114
The availability and price of suitable raw materials will often determine the site
location. Plants producing bulk chemicals are best located close to the source of
the major raw material; where this is also close to the marketing area.

3- Transport

The transport of materials and products to and from the plant will be an
overriding consideration in site selection.

4- Availability of labor

Labor will be needed for construction of the plant and its operation. Skilled
tradesmen will be needed for plant maintenance.

5- Utilities (services)

Chemical processes invariably require large quantities of water for cooling and
general process use, and the plant must be located near a source of water of
suitable quality. Process water may be drawn from a river, from wells, or
purchased from a local authority.

6- Environmental impact and effluent disposal.

All industrial processes produce waste products, and full consideration must be
given to the difficulties and cost of their disposal. An environmental impact
assessment should be made for each new project, or major medication or
addition to an existing process.

7- Land (site considerations)

Sufficient suitable land must be available for the proposed plant and for future
expansion. The land should ideally be flat, well drained and have suitable load-
bearing characteristics.

8- Climate

Adverse climatic conditions at a site will increase costs. Abnormally low

temperatures will require the provision of additional insulation and special
heating for equipment and pipe runs. Stronger structures will be needed at
locations subject to high winds (cyclone/hurricane areas) or earthquakes.

115
5.1.2: Site Layout

The process units and ancillary buildings should be laid out to give the most
economical flow of materials and personnel around the site. Hazardous
processes must be located at a safe distance from other buildings. The ancillary
buildings and services required on a site, in addition to the main processing
units (Buildings) will include:

1- Storages for raw materials and products: tank farms and warehouses.

2- Maintenance workshops.

3- Stores, for maintenance and operating supplies.

4- Laboratories for process control.

5- Fire stations and other emergency services.

6- Utilities: steam boilers, compressed air, power generation, refrigeration,

transformer stations.

7- Effluent disposal plant.

8- Offices for general administration.

9- Canteens and other amenity buildings, such as medical centers (Sinnott et al

., 2005)

116
5.1.3: Styrene Monomer Plant Location:

Based on these previous factors which are required in styrene monomer

manufacturing plant, we select Al-Samawa city as plant location in a place at
which the wind pass through the plant must not hit the cities.

This location will provide to the plant utilities which need since it near Al-
Samawa Refinery which provide low cost of transport requirement of ethylene,
also labors and local community which satisfied the labor requirement.

5.2 Health and safety

117
Styrene is mildly toxic and inflammable, and it can polymerize violently under
specific conditions. However, none of the hazard associate with styrene is
severe, and it is considered a relatively safe organic chemical when handled
according to appropriate safe guards. Styrene has an odor threshold of .05-.15
ppmv. Both liquid and vapor irritate the eye and respiratory system, and high
vapor concentration results in depression of central nervous system. Irritation of
eye and respiratory tract occurs at 400-500 ppmv, but does not result in
permanent injury. Test animals for one hr serious systematic effects can tolerate
concentration up to 2500 ppmv. Exposure for 30-40 min to a conc. of 10000
ppmv may be fatal.

Styrene is low in oral toxicity. Contact with eyes is painful, but results in
transient

damage. Short term contact with skin, do not cause irritation; however
prolonged contact may cause swelling, blistering. However, styrene as it is
commonly store and transported contains TBC, which is skin sensitizer. Styrene
monomer is flammable and can form explosive mixture with air at atmospheric
ambient condition. It is generally suggested to store & handle styrene below or
at atmospheric temp. Polymerization of styrene is an exothermic reaction and
proceeds slowly at room temperature. Thus, there is potential for a runaway
polymerization reaction, which may results in an accelerating evolution of
styrene vapor that may cause fire or rupture in the confining vessel. The
polymerization reaction is generally been prevented by adding TBC inhibitor.
Effective inhibition of polymerization by TBC occurs in presence of dissolved
oxygen, and so storage in an atmosphere-permeable tank is preferred, where
inert gas blanketing of the stored material is to be done. Periodic air addition is
recommended to maintain the

118
presence of dissolved oxygen. For the areas, where, average temperature is over
27o C, additional refrigeration is required.

MEASURES:

• The efficiency of the, condenser should must be properly justified, so that

there be minimum loss of styrene in the atmosphere.

• The reactor is generally made adiabatic, and the reaction is endothermic. The

heat of reaction is generally supplied by adding steam at 800o C. This steam is

then condensed and separated as an aqueous solution, saturated with different

organic chemical. To maintain the proper industrial economy, this condensate

must be treated and recycled back at maximum possible limit.

• The heavy end from the final column, contain styrene polymers and some
styrene derivatives, which have good economical values. However, disposal of
this heavy end causes problem. So by adopting proper separation method it is
desired to separate those components of high economical values.

• In order to prevent the chance polymerization, final treatments are generally

carried out under reduced temperature and low pressure.

119
CAHPTER SIX
ECONAMIC
COST

120
6.1: Economic Studies
To determine whether a project is feasible and attractive enough for investment,
Acceptable plant design must present a process that is capable of operating
under conditions which will yield a profit.
Economic Potential
EP = Revenue – Raw Material
Compare between:
1-Recycle Stream Neglected, 2-Recycle Stream Include
Recycle Stream NEGLECTED
EP = (Styrene Cost) – (Ethyl benzene Cost +Toluene Cost + Benzene Cost)
So, before including recycle stream:
EP = 61764914.65 $ – 147738127.5 $
= - 859732212.85 $ (negative value)
Economic Potential 1 (EP1)
EP1 = Revenue – Raw Material
EP = (Styrene Cost) – (Ethyl benzene Cost +Toluene Cost + Benzene Cost)
So, by including recycle stream:
EP1 = 61764914.65 $ - 28820478.2 $
= 32944436.45 $ (positive value)

6.2: Cost of designed equipment:

The choice of appropriate equipment often is influenced by considerations of
price. A lower efficiency or a shorter life may be compensated for by a lower
price. Funds may be low at the time of purchase and expected to be more
abundant later, or the economic life of the process is expected to be limited.

121
6.2.1 Reactor cost

4 62

1 54

Using figure 6.3 b ,VOL (6).

19000 1 1 19000 2004

2013
2013 2004
2004

From figure 6.1b,VOL (6),finding the cost index by extrapolation.

135 75
2013 19000
111

2013 23236 48 23236

4 3016 550

2365

2013

23236 2365

25602

122
6.2.2 shell and tube heat exchanger cost

540

Using figure 6.3 b ,VOL (6).

80 000 0 8 1 64 000 2004

From figure 6.1 a, finding the cost index by extrapolation .

2013
2013 2004
2004

135 75
64 000 78 270 27 78 270
111

123
Appendix A:

A-1: Basic physical properties of the main components:

Component
Name Name

Styrene C8H8 145.1 36844 147460 104

Ethyl benzene C8H10 136.1 35588 29810 106
Benzene C6H6 80.1 30781 82980 78
Toluene C7H8 110.6 33201 50030 92
Methane CH4 -161.5 8185 -74860 16
Ethylene C2H4 -103.8 13553 52330 28
Hydrogen H2 -252.8 904 ………… 1
Water H2O 100 40683 -242000 18

A-2: Antoine equation:

Component A B C
Styrene 16.0193 3328.57 -63.72
Ethyl benzene 16.0195 3272.47 -59.95
Benzene 15.9008 2788.51 -52.36
Toluene 16.0137 3096.52 -53.67

A-2: Heat capacities of gases:

124
 Component

C8H10 -43.099 70.715 - 4.811 130.08

C8H8 -28.248 61.588 - 4.023 99.353

C6H6 -33.917 47.436 - 3.017 71.301

C7H8 -24.355 51.246 - 2.765 49.111
CH4 19.251 5.2126 0.11974 - 11.32

C2H4 3.806 15.659 - 0.8348 17.551

H2 27.143 0.92738 - 0.1381 7.6451
steam 32.2168 0.001922 0.1055 -3.593

A-3: Heat capacities of liquid:

Component
C8H10 102.11 5.5959 -1.5609 2.0149
C8H8 66.737 8.4051 -2.1615 2.3324
C6H6 -31.663 13.043 -3.6078 3.8243
C7H8 83.703 5.1666 -1.491 1.9725
CH4 -0.018 11.982 -9.8722 31.67
C2H4 25.597 5.7078 -3.362 8.412
H2 50.607 -61.136 309.3 -4148
H2O 92.053 -0.39953 -0.21103 0.53469

125
A-4: viscosity of gas:

Component
C8H10 -4.267 2.4735 -54.264
C8H8 -10.035 2.5191 -37.932
C6H6 -0.151 2.5706 -8.9797
C7H8 1.787 2.3566 -9.3508
CH4 3.844 4.0112 -143.03
C2H4 -3.985 3.8726 -112.27
H2 27.758 2.12 -32.8
H2O -36.826 4.29 -16.2

126
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