1. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 94-102 © IAEME
94
OPTIMIZATION AND PERFORMANCE EVALUATION OF AN
EXISTING CRUDE OIL DISTILLATION SYSTEM
Ali KhudhairKnehir, Dr. Ajeet Kumar Rai*, Dr. Abdulwahid A. Al-Hajjaj
Deptt of Fuel and energy Engg. Technical college of Basrah, Republic of Iraq-32001
*Deptt of Mech. Engg. SSET, SHIATS-DU Allahabad (U.P.) INDIA-211007
ABSTRACT
Crude Distillation Units are key process plants in a petroleum refinery as they produce
intermediate streams that are used in downstream process units. In fact, the crude oil separation is a
complex atmospheric multi-components distillation process. The process complexity is arise mostly
from the large number of components in the crude oil. An existing crude distillation unit is costly to
modify due its complex configuration and existing limitations of structure, space area, matches,
bottlenecked equipments, etc. Thus, a few new crude distillation units are built and most projects are
directed to revamping existing equipments. Modifying an existing plant have a great impact on
product yield and quality through operating these units at optimal conditions from technical and
economical aspects; that means operating conditions such as temperatures, pressures and flows of the
units that maximize their economic performance (increasing product yield), subject to their real
physical restrictions and their design capabilities. Mathematical modeling has become very common
to develop these optimization studies. In the present work, Genetic algorithm (GA) method will be
adapted to solve the optimization problems. GA is a powerful optimization technique based on the
principles of natural evolution and selection. In the specific case of selecting the optimum set of
inputs from a larger set, GA can be used to search through a large number of input combinations
with interdependent variables to be designed for the crude oil distillation column. For mathematical
description of a distillation process in refining columns, the theoretical stage method is usually used.
The number of theoretical stages of an existing column is estimated by multiplication of the real
number of stages and column efficiency. The present methodology will apply to a local atmospheric
plant for Basrah refinery, as an Iraqi refinery case study. The optimization approach will focus on the
efficient reuse of existing equipment without major modifications and will be achieved by changing
operating condition without adding any new equipment. The mathematical modeling will be carried
out in the following procedure. Target variables: Total flow rate, reflux ratio, the concentration of
key components, the draw amount of the key components and the liquid flow rate of the column
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2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp.
inter-stage. Case study data are industrial actual data obta
and analysed using HYSYS software.
INTRODUCTION
The crude oil separation process becomes increasingly important because of the high energy
costs and ecological requirements for quality oil products. Computer simulation is one of the most
important steps of process optimization. However, due to complex c
design of oil fractionators, simulation of oil distillation requires a specific approach( Asok Kumar
2012) Crude oil (or petroleum) is a multicomponent mixture consisting of naturally occurring
hydrocarbons, together with organic compounds of sulphur, nitrogen and oxygen, as well as trace
amounts of metallic constituents, such as vanadium, nickel and iron. The origin of crude oil can have
a significant effect on its composition. As a result, crude oils widely vary in volatility
viscosity and color. Crude oil may also contain dissolved inorganic gases, such as nitrogen, carbon
dioxide, and hydrogen sulphide, at high pressure and temperature conditions. Water is another
important constituent of produced crude oil. As wat
most of the water is usually found in the form of emulsified droplets or in a free water phase. The
free water is usually separated at the well
the pre-refining operations (TomášPavlík 2009) .In petroleum refining, the boiling point ranges are
used instead of mass or mole frictions. Three types of boiling point analysis are known: ASTM D86,
ASTM D158 and TBP (true boiling point). Properties of a petroleum
terms of composition. Instead, properties such as 5 % point, 95% point, final boiling point, flashpoint
and octane number are used. The method for quantitative calculations of the petroleum frictions is to
break them into pseudo components each pseudo component has its average boiling point, specific
gravity, and molecular weight.
Separation Units
These units take an incoming stream and
reactions occur in these units to thedesalted
and may deactivate the catalysts. It is important to remove these salts from the crude before any o
processes are started. The process involves
out the salts and prevents corrosion.
Figure 1:
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976
6499(Online) Volume 5, Issue 4, April (2014), pp. 94-102 © IAEME
95
stage. Case study data are industrial actual data obtained. The simulation frame work
software.
The crude oil separation process becomes increasingly important because of the high energy
costs and ecological requirements for quality oil products. Computer simulation is one of the most
important steps of process optimization. However, due to complex composition of oil and complex
design of oil fractionators, simulation of oil distillation requires a specific approach( Asok Kumar
2012) Crude oil (or petroleum) is a multicomponent mixture consisting of naturally occurring
nic compounds of sulphur, nitrogen and oxygen, as well as trace
amounts of metallic constituents, such as vanadium, nickel and iron. The origin of crude oil can have
a significant effect on its composition. As a result, crude oils widely vary in volatility
viscosity and color. Crude oil may also contain dissolved inorganic gases, such as nitrogen, carbon
dioxide, and hydrogen sulphide, at high pressure and temperature conditions. Water is another
important constituent of produced crude oil. As water has limited miscibility with hydrocarbons,
most of the water is usually found in the form of emulsified droplets or in a free water phase. The
free water is usually separated at the well-head facilities, while the emulsified water is removed in
(TomášPavlík 2009) .In petroleum refining, the boiling point ranges are
used instead of mass or mole frictions. Three types of boiling point analysis are known: ASTM D86,
ASTM D158 and TBP (true boiling point). Properties of a petroleum stream are not specified in
terms of composition. Instead, properties such as 5 % point, 95% point, final boiling point, flashpoint
method for quantitative calculations of the petroleum frictions is to
break them into pseudo components each pseudo component has its average boiling point, specific
These units take an incoming stream and separate it into different components no chemical
desalted Ions in the crude oil will corrode the pipes in the refinery
and may deactivate the catalysts. It is important to remove these salts from the crude before any o
process involves forcing water into the crude oil feed stream. This pulls
Crude distillation unit parts "Desalter“
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
© IAEME
ined. The simulation frame work is studied
The crude oil separation process becomes increasingly important because of the high energy
costs and ecological requirements for quality oil products. Computer simulation is one of the most
omposition of oil and complex
design of oil fractionators, simulation of oil distillation requires a specific approach( Asok Kumar
2012) Crude oil (or petroleum) is a multicomponent mixture consisting of naturally occurring
nic compounds of sulphur, nitrogen and oxygen, as well as trace
amounts of metallic constituents, such as vanadium, nickel and iron. The origin of crude oil can have
a significant effect on its composition. As a result, crude oils widely vary in volatility, density,
viscosity and color. Crude oil may also contain dissolved inorganic gases, such as nitrogen, carbon
dioxide, and hydrogen sulphide, at high pressure and temperature conditions. Water is another
er has limited miscibility with hydrocarbons,
most of the water is usually found in the form of emulsified droplets or in a free water phase. The
head facilities, while the emulsified water is removed in
(TomášPavlík 2009) .In petroleum refining, the boiling point ranges are
used instead of mass or mole frictions. Three types of boiling point analysis are known: ASTM D86,
stream are not specified in
terms of composition. Instead, properties such as 5 % point, 95% point, final boiling point, flashpoint
method for quantitative calculations of the petroleum frictions is to
break them into pseudo components each pseudo component has its average boiling point, specific
separate it into different components no chemical
Ions in the crude oil will corrode the pipes in the refinery
and may deactivate the catalysts. It is important to remove these salts from the crude before any other
forcing water into the crude oil feed stream. This pulls

3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 94-102 © IAEME
96
Atmospheric Distillation: The distillation is performed at atmospheric pressures. The outputs
of the distillation unit include light ends, kerosene, diesel, heavy gas oil, atmosphericresidue.
Figure 2: Distillation tower bubble cup tray
The Vacuum Distillation: This unit distills the atmospheric residue and produces light
vacuum gas oil, heavy vacuum gas oil, and vacuum residue. The distillation occurs because the
pressure inside of the unit is decreased to nearly zero, allowing the components of the atmospheric
residue to boil at a lower temperature.
Figure 3: vacuum distillation tower

4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 94-102 © IAEME
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PROCEDURE
The crude oil first enters the desalter to remove any salts that may corrode the processing
units. From there, the desalted crude enters the atmospheric distillation unit. The separated
components are as follows: light distillates, kerosene, light gas oil (diesel), heavy gas oil (fuel oils),
and atmospheric residue. The light distillates enter the light ends unit, where they are further
separated into several more distinct components. The methane and ethane is captured and burned to
provide heat for other processes. Propane and butane are first hydro treated before being sold as
LPG. The light straight run naphtha is sent to the gasoline blending pool and the heavy straight run
naphtha is hydro treated and then sent to the catalytic reform to produce high octane gasoline. The
straight run kerosene is hydro treated before being sold as a final product, which is mostly jet fuel.
The straight run diesel is also hydro treated before being sold to the public. Hydro treating the diesel
remains extremely important due to the increasing governmental restriction on its sulfur content. The
heavy gas oil is either sold as low grade fuel oil or more often it is upgraded using fluid catalytic
cracking to produce more desirable products. The atmospheric residue is sent to vacuum distillation.
The light vacuum gas oil is further refined using a visbreaker and then sold as a fuel oil. The heavy
vacuum gas oil is hydrocracked to produce gasoline and other products. The vacuum residue is sent
to a deasphalter, producing asphalt and a deasphalted oil, which is further treated to produce fuel
oils, or to a coker. Finally, various processes, such as the fluid catalytic cracker and coker provide
the feed stocks for the alkylater.
RESULTS AND DISCUSSION
Figure (4): Variation of temperature of the products with time.
This figure shows the different types of the products in the outlet of the distillation unit as we
can see here the light products such as "Benzene, Light gas oil, light straight run" with low TBP will
be drawn off from the top of the distillation column. The remain products with high TBP will be
drawn off from the bottom of the distillation tower.
0
100
200
300
400
500
600
7:00
8:00
9:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
24:00:00
1:00
2:00
3:00
4:00
5:00
6:00
TEMP.
time per day
LIGHT STRIGHT RUN LIGHT GAS OIL REDUCED CRUDE
BENZENE NAPTHA HEAVY KEROSENE

5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 94-102 © IAEME
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.
Figure (5): Variation of Temperature and Mass percent of the feed
Figure (6): Variation of mass fraction of total oil and boiling point

6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 94-102 © IAEME
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Figure 7: Regression analysis between the operational and optimum flow rate of HGO
Figure 8: Regression analysis between the operational and optimum flow rate of Naphtha
R² = 0.9565
44
46
48
50
52
54
56
58
60
42 44 46 48 50 52 54 56 58
optimumvalu(m3/hr)
Operational value (m3/hr)
Data sets
Linear (Data sets)
R² = 0.9606
30
31
32
33
34
35
36
28 30 32 34 36 38
optimumvalu(m3/hr)
Operational value (m3/hr)
Data sets
Linear (Data sets)

7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 94-102 © IAEME
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Figure 9: The correlation between the optimal and regroius simulation results of products' flow rates
In Figure(9) the correlation between the optimal and the simulated flow rate of the distillation
column products is illustrated with best linear fit and the correlation coefficient. The value of the
correlation coefficient (R2
) for the test data is 0.997, which indicates a very good correlation between
optimum and operational data.
Table 1: Comparison of product flow rate with rigorous simulation
Optimal result
m3
/hr
Simulated result
m3
/hr
Products
51.5
55.2
Benzene
30.3
33.8
Naphtha
55.6
57.3
Heavy kerosene
195.2
190.7
Light distillate
80.472.8Light gas oil
50.547.0Heavy gas oil
208.2206.8Reduced crude
R² = 0.997
0
50
100
150
200
250
0 50 100 150 200 250
Optimalflowrate(m3/hr)
Simulated flow rate (m3/hr)
Predicted data
Linear (Predicted data )

8. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 4, April (2014), pp. 94-102 © IAEME
101
CONCLUSION
Simulation and optimization of the crude oil separation process becomes increasingly
important because of the high energy costs and ecological requirements for quality oil products.
Computer simulation is one of the most important steps of process optimization. However, due to
complex composition of oil and complex design of oil fractionators, simulation of oil distillation
requires a specific approach. The crude oil distillation unit is a unit of major importance in every
refinery system. The present work concerned the application of HYSYS for the analysis of the
operation of an atmospheric distillation unit of a crude oil refinery. Steady-state simulation of an
existingatmospheric crude oil distillation column is performed using real operating data of Basrah
refinery, IRQA. The simulation results were in good agreement with operational data.A hybrid
optimization algorithm which combined the HYSYS simulation method and genetic algorithm (GA)
is proposed. The proposed algorithm constitutes a reasonable framework, capturing both the
operating condition and the production performance of the studied atmospheric distillation unit.The
operational and the calculated values from the proposed network of flow rates of the major
components of the distillation unit products is compared. The correlation coefficients (R2
) obtained
for benzene, naphtha, Heavy kerosene (HK), Light distillate (LD), Light gas oil (LHO), Heavy gas
oil (HGO) and Reduced crude (RC) flow rates are 0.9706, 0.9606, 0.9183, 0.9744, 0.9824, 0.9565
and 0.9728 respectively, which indicates that the proposed methodology can be used to predict
design variables (output variables) of the crude oil distillation column.
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AUTHOR’S DETAIL
Ali KhudhairKnehir was born in Basrah at September 1988, he received his B.Sc.
from Basrah Technical college, Fuel and energy Eng.Tech department at 2010-
Ministry of higher education and scientific research, Republic of Iraq, he completed
his M.Tech. in Mechanical Engineering (Thermal Engineering) form Sam
higginbottom Institute of Agriculture Technology &sciences, at 2014, Allahabad,
U.P, India.
Dr A. K. Rai is born in 1977, Distt. Ballia (Uttar Pradesh) India. He received his
M.Tech Degree from MNNIT Allahabad in Design of Process Machines andPh.D.
from SHIATS- DU Allahabad in2011.He has been in GBPUAT Pant Nagarfrom
2003 to 2005. He is Joined SHIATS-DU Allahabad as assistant Professorin2005.
He has published more than 25 papers in international journals. He hasdelivered
expert lectures in many national and International conferences.