International Journal of Research in Engineering and Science (IJRES)

ISSN (Online): 2320-9364, ISSN (Print): 2320-9356

www.ijres.org Volume 6 Issue 7 Ver. I ǁ 2018 ǁ PP. 40-45

Paper Title (16 Bold)

Author (14)
*1
Department of Chemical Engineering, University of Port Harcourt, Port Harcourt, Nigeria
2
Department of Chemical Engineering, University of Port Harcourt, Port Harcourt, Nigeria
3
Department of Chemical Engineering, University of Port Harcourt, Port Harcourt, Nigeria
Corresponding Author: xxxx (10)

Abstract (11 Bold)

The aim of this paper is to determine the effect oftemperature o linear alkylbenzene (LAB) yield from a Nigeria
Refinery LAB plant. The rerun (LAB) column was simulated using Aspen HYSYS. The simulation was done at
temperatures between 280oC and 360oC at temperature difference of 20 oC (ΔT =20°C).There was an increase in
the average weight percentage fraction of linear alkylbenzenes at the bottom stream temperature from 280 oC to
340oC and a slight decrease at 360 oC. Bottom stream temperature280oC and pressure of 115Kpa yielded the
highest LAB percentage yield of 99.4%.
Keywords: (11 Bold)Rerun column Top stream temperature, Rerun column bottom streamand Linear
alkylbenzene Yield.
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Date of Submission: xx-xx-xxxx Date of acceptance: xx-xx-
xxxx
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I. INTRODUCTION (10 Bold)

Linear alkyl benzene (LAB) is a family of organic compounds with C 6H6 – CnH2+1 C n H 2+ 1 (n is
between 10 and 16). The C12 – C15, C10 – C13 LABs are used for detergent production and are produced by the
reaction between paraffins and Benzene [5]. LABs are currently being used as a liquid scintillator in neutrino
detector due to its good optical transparency, its high yield, low amount of radioactive impurities and high flash
points [5]. It is also a suitable material that is being used in a secret Neutrino Interaction Finder (SNIF), it is
also used as an antineutrino detector design to detect the presence of nuclear reactor at a distance of 100 –
500KM [5].
After the HF acid has been stripped out by the HF stripper, the benzene in the stream is then recycled to
the alkylation reactor section from the overhead of the benzene column, while n-paraffins are recycled to the
PACOL unit from the overhead of the paraffin column [7, 8].
The product of alkylation unit serves as feed to the HF stripper column – after benzene has been
reacted with mono-olefins to form linear alkylbenzene (LAB) in the presence of HF acid catalyst [6, 9].
Linear Alkyl benzene is a vital raw material in the production of liner alkyl benzene sulphonate [1, 2].
The LABs C10H22C6C6, C11H24C6C6, C12H26C6C6, C13H28C6C6 and C14H30C6C6 produced by the reaction
between paraffins and benzene are essential raw materials for producing detergent [5, 9].
The factors that can affect biodegradability of linear alkylbezene sulphonate (Detergent) includes the
structure of side hydrocarbon chain in molecule and the share of 2-phenylalkane among other isomers [4].

1.1.1 Fractionation Section

The light ends produced by cracking reaction are removed in the stripper column. The off -gas from the
stripper is sent to the fuel gas, but flared if it is under high pressure[3] . And the paraffins and olefins in the
column bottom stream are fed to the linear alkyl benzene alkylation unit. In order to recover enough heat from
the bottom stream, it is necessary by passing where the paraffin stream is heated [3].

1.1.2 Aspen HYSYS

This is a chemical process design software or application used for designing, monitoring trouble shooting and
analyzing the technical and economic performance of a chemical process plant [6].
The steps used for running flow sheet simulation in Aspen HYSYS were as follows:
i. Components selection.
ii. Thermodynamic options selection.
iii. Computing feeds composition and thermodynamics.
iv. Creating a flow sheet.

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 Effect Of Temperature On Linear Alkylbene (Lab) Yield From Rerun Column
v. Naming the feed stream.
vi. Equipment parameters computation.
vii. Collection of result from the simulated environment [6].

Figure1: Linear alkylbenzene flow diagram (UOP 2009[2])

1.2 THE SIMULATION

1.2.1 The Linear alkylbenzene (rerun column) was simulated at steady state using a distillation column
template of ASPEN HYSYS 8.8. Peng Robinson was selected as the fluid package.
Figure 2:represent the simulated flow diagram for the linear alkylbenzene (rerun) column

Figure 2:Aspen HYSYS linear alkylbenzene Column Plant View

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 Effect Of Temperature On Linear Alkylbene (Lab) Yield From Rerun Column
1.2.2 Rerun column Design specifications

Table 1 represents the rerun column design specification.

Table 1: Rerun Column, Specification.
Specification
Striping Column diameter 2800mm
Rectification Section diameter 5600mm
Tray spacing 600mm
Number of tray holes 1942
Hole diameter 13mm
Number of Trays above feed 15 trays, 16 stages (with condenser)
Number of Trays below feed 21 trays, 22 stages (with re-boiler)
Q c (Condenser heat duty) 31212 MJ/hr

Q r (Re-boiler heat duty) 22363 MJ/h

1.2.3 Feed Components and composition

Table 2 indicates the LAB column feed stream components the composition in wt. % fraction.

Table 2: Feed Components used and their Composition in weight % fraction.

Components Chemical Formula Composition (wt. % fraction)
1. N-Decane nC10H22 0.0003
2. N-Undecane nC11H24 0.0033
3. N-Dodecane nC12H26 0.0046
4. N-Tridecane nC13H28 0.0058
5. N-Tetradecane nC14H30 0.0065
6. N-Pentadecane nC15H32 0.1086
7. N-Hexadecane nC16H34 0.0166
8. Decylbenzene nC169H26 0.1439
9. N-undecylbenzene nC17H28 0.1775
10. N-dodecylbenzene nC18H30 0.2032
11. N- tridecylbenzene nC19H32 0.1626
12. N-tetradecylbenzene n-C20H34 0.1071
13. Heavy Alkylates n-C26H54 0.0599

2.2.4 Rerun column Operating Conditions

The operating conditions of the LAB (rerun) column is as represented in table 3

Table 3 Operating Conditions used in this Simulation are as stated below.

Feed Top Stream (Distillate) Bottom
Temperature °C 178 93 232
Pressure Kpa 200 9.0 20
Enthalpy MJ/h -95850 -98130 -125900
Mass Flow-rates Kg/h 140400 108900 14290

II. RESULT AND DISCUSSION (10 Bold)

The results obtained are as discussed below

1.3.1 LAB Average Weight fraction.

(i) At Top stream Operating temperatures ΔT=20oC
The average weight fraction of n-decylbenzene, n-undecylbenzene and n-dodecylbenzene increased at the top
stream operating temperature of 280oC – 300oC and decreased at 320oC – 360oC. While n-tridecylbenzene and
n-tetradecylbenzene decreased at 280oC – 300oC and increased at 320oC – 360oC.

Table 4:Average Weight fraction of LAB at Top Stream Operating Conditions ΔT=20oC.
Linear Alkylbenzenes (LAB) Operating Temperatures( oC)
280 300 320 340 360
n-decylbenzene 0.2792 0.2984 0.2849 0.2791 0.2740
n-undecylbenzene 0.2177 0.2800 0.2740 0.2714 0.2694
n-dodecylbenzene 0.2842 0.2762 0.2807 0.2820 0.2832
n-tridecylbenzene 0.1658 0.1566 0.1638 0.1675 0.1705
n-tetradecylbenzene 0.0885 0.0832 0.0889 0.0927 0.0950

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 Effect Of Temperature On Linear Alkylbene (Lab) Yield From Rerun Column
0.3

Average Wt. % fraction of LAB 0.25

0.2
n-decylbenzene
n-undecylbenzene
0.15 n-dodecylbenzene
n-tridecylbenzene
0.1 n-tetradecylbenzene

0.05
270 290 310 330 350 370
Temperature oC

Figure 3: Average Weight fraction of LAB at Bottom Stream Operating Conditions

(ii) At Bottom stream Operating temperatures ΔT=20oC

The average weight fraction of n-decylbenzene, n-undecylbenzene and n-dodecylbenzene increased at the
bottom stream operating temperature of 280oC – 320oC and decreased at 340oC – 360oC. While that of n-
tridecylbenzene and n-tetradecylbenzene remains constant. Table 4 and Fig.4

Table 4: Average Weight fraction of LAB at Bottom Stream Operating Conditions ΔT=20oC.
Linear Alkylbenzenes Operating Temperatures(oC)
280 300 320 340 360
n-decylbenzene 0.2390 0.2393 0.2404 0.2419 0.2401
n-undecylbenzene 0.2558 0.2561 0.2568 0.2569 0.2568
n-dodecylbenzene 0.2797 0.2808 0.2831 0.2829 0.2837
n-tridecylbenzene 0.1897 0.1897 0.1897 0.1897 0.1897
n-tetradecylbenzene 0.1113 0.1113 0.1113 0.1113 0.1113
0.3
Average weight fraction for LAB

0.25

n-decylbenzene
0.2
n-undecylbenzene
n-dodecylbenzene
0.15 n-tridecylbenzene
n-tetradecylbenzene

0.1
270 290 310 330 350 370
Temperature oC

Figure 4: Average Weight fraction of LAB at Bottom Stream Operating Conditions

4.2.4 LAB Average wt. % fraction Yield

The calculated LABs percentage Yield from the average LAB weight fraction is as shown in Table 4.3
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 Effect Of Temperature On Linear Alkylbene (Lab) Yield From Rerun Column
The calculated percentage yield of average LAB wt. % fraction indicated a higher percentage yield at the top
and bottom stream temperature of 280oC. At this temperature the obtained yield of top and bottom streams are
92.2% and 95.3 %. Table 5 and Figure

Table 5: LAB Average wt. % fraction Percentage Yield

Operating *Temperatures Percentage Yield of Average LAB wt.% at Percentage Yield of Average LAB wt.% at
(0C) various Top Stream operating condition various Bottom Stream operating condition
280 92.2 95.3
300 87.6 94.8
320 87.5 94.2
340 87.6 93.8
360 87.5 93.3

95

94

93
Percentage Yield

92
Average LAB wt.% at
various Top strem Temp.
91
Average LAB wt.% at
various Bottom strem Temp.
90

89

88

87
270 290 310 330 350 370
Temperature oC
Figure 5:LAB Average wt. % fraction Percentage Yield

5 Percentage Yield of LAB in the distillate at TBottom= 280 0C.

 The bottom stream operating temperature of 280 0C has the highest average percentage yield of linear
alkylbenzenes (LABs). The percentage yield of the linear alkylbenzene was calculated by keeping the operating
temperature at 280 0C and varying the operating pressure at 17Kpa, 42Kpa, 67Kpa, 92Kpa and 115Kpa. The
highest yield obtained is 99.4% which is at 115Kpa. This is as shown in Table 6. And figure 6

Table 6: Percentage Yield of LAB in the distillate.

Pressure Kpa Percentage Yield Of LAB in the Distillate
17 89.1%
42 95.4%
67 97.9%
92 98.97%
115 99.4%

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 Effect Of Temperature On Linear Alkylbene (Lab) Yield From Rerun Column

102
100
98
96
94
LAB % Yield

92 Percentage Yield of LAB in

the Distillate
90
88
86
84
82
0 20 40 60 80 100 120 140
Pressure Kpa.
Fig.6:LAB % Yield at TBottom= 280oC.

III. CONCLUSION (10 Bold)

It was observed that the rerun column bottom stream temperature has greater effect on the linear
alkylbenzene yield than the temperature variation of the top stream. At higher temperature of both streams ,
lower percentage yield of average wt. % of linear alkylbenzene was obtained with that of the top stream being
the lowest at 87.5% as against 93.3% for the bottom stream. The highest linear alkylbenzene yield of 99.4%was
recorded at bottom stream temperature of 280oC and pressure of 115Kpa.

IV. REFERENCES (10 Bold)

[1]. Abiola K. “Strategy for Development of the Petrochemicals Industry in Nigeria” A paper submitted to the Department of chemical
Engineering, University of Lagos.
[2]. Aderogba, K. A. (2011)” Significance of Kaduna River to Kaduna Refining and Petrochemicals Complex” African Journals, Vol. 5
(5), Serial No. 2 Pp.83-98.
[3]. Ahmad Daaboul. “LAB Project - Environmental Impact Assessment” Section 3 pp. 4 – 42
[4]. Irena O. D, Dolganov I.M and Ivanshkina E.N (2001) “Development of Computer Modeling System as a Tool for Improvement of
Linear Alkylbenzene Production” J. Petroleum and Coal. Vol. 53,No.4, Pp. 244 – 250
[5]. Sadal O.I.,Marwa S.M.,Wala T.A. (2012) “Linear Alkylbenzene Production from Kerosene” Seminar presented to the Department
of Chemical engineering University of Khartoum.
[6]. Thaer, A. A. (2010), “Process Simulation Analysis of HF Stripping Column Using HYSYS Process Simulator” J. of Engineering
Sciences /Vol.17/No.2, pp.87 – 96.
[7]. UOP (1990) “Linear Detergent Alkylation Unit, General Operating Manual” pp. 1 –610.
[8]. UOP (2004) “Linear Detergent Alkylation Unit, General Operating Manual” Pp. 1 – 112.
[9]. Xiaoming J, Gang Rong and Shuqing Wang (2003), “Modelling and Advanced Process Control (APC)For Distillation Columns of
Linear Alkylbenzene Plant Key Lab of Industrial Control Technology, Institute of Advanced Process Control, Zhejiang University,
pp1-6.

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