ICCPGE 2016, 1, 25 - 30
Refinery Configurations for Maximum Gasoline Production
from Libyan Crude Oil
Elmahboub A. Edreder1,* , Ammar M. Ghayth2 , Salah A. Algaryani3
1
National Oil Corporation, Tripoli, Libya
2
Nuclear Research Center,Radiation Chemistry, Tripoli, Libya
3 Department of Chemical Engineering, University of Tripoli, Tripoli, Libya
* Corresponding Author: eelmahboub@yahoo.com
Abstract
In this work, different refinery configurations are investigated for upgrading projects to increase
gasoline production for local market demand. Different alternatives for the upgrading can be tackled.
Either direct upgrading of the atmospheric residue, or first subject the atmospheric residue to vacuum
distillation then upgrade the vacuum residue and vacuum gas oil to more valuable and lighter products.
Obtained results show that, the scenario which included fluidized catalytic cracking (FCC) has shown
the optimum in terms of both maximum gasoline and less capital cost compared with configuration
that included the delayed coking process.
Keywords: Refinery; Gasoline; FCC; Delayed coking;Crude oil.
1. Introduction
Crude oil is a complex liquid mixture made up
of a vast number of hydrocarbon compounds that
consist mainly of carbon and hydrogen in differ-
ing proportions. In addition, small amounts of
organic compounds containing sulphur, oxygen,
nitrogen and metals such as vanadium, nickel,
iron and copper are also present. The purpose of
refining is to convert natural raw materials such Figure 1.1: Worldwide Refining Consolidation
as crude oil and natural gas into useful saleable
product. Worldwide Crude oil refining (million
bbl/cd) and number of refineries are shown in Fig- separation, conversion, and purification. Separa-
ure 1.1. tion is performed in a series of distillation towers.
The overall economics or sustainability of a refin- The yield from a distillation tower refers to the
ery depends on the interaction of three keys: the relative percentage of each the separated compo-
choice of crude oil used (crude slates), the com- nents, known as product streams. Products from
plexity of the refining equipment (refinery config- the distillation tower range from gases at the top
uration) and the desired type and quality of prod- to viscous liquids the bottoms. In all cases, these
ucts produced (product slate). At the refinery, product streams are still considered unfinished
crude oil is treated and converted into consumer and require further processing to become useful
and industrial products. Three major refinery products. Distillation separates the crude oil into
processes change crude oil into finished products: unfinished products. However, the products do
25
not naturally exist in crude in the same properties Table 2.1: Refinery configurations
as the product mix that consumers demand. The
biggest difference is that too little gasoline and Process Units Sc1(existing Sc2 Sc3
too much heavy oil naturally occurring in crude unit)
oil. That is why conversion processes are so im- Atmospheric √ √ √
portant. Their primary purpose is to convert low Distillation
valued heavy oil into valued gasoline. Vacuum Distillation √ √ √
Modern refinery and petrochemical technology can Catalytic Reforming √ √ √
transform crude oil into literally thousands of use- Fluidized Catalytic √
ful products, from powering our cars and heating cracking
our homes, to supply petrochemical feedstocks for Delayed Coking √
producing plastics and medicines.
Refining performance is improved by considera-
tion of the following factors: Gupta and Gera [5] highlighted the upgrading
• The ability to process crude oil into high-volume of residue or heavy oil using thermal and cat-
marketable products and generating high yields alytic hydrocracking processes such as visbreak-
of those products. ing, Nanoparticles; Biological processing of heavy
fractions. In the present study, optimization of
• Selection of the crude feedstock from which the the selected refinery configurations, particularly
refinery can generate the highest product price the residue processing schemes, were carried out
differential or crack. so as to maximize the gasoline refinery yield.
• Optimizing the selection of crude, timing of
throughput, and matching the product slate to 2. Refinery Configurations
market demand.
Refineries are classified according to the number
• Tight control of both fixed and variable oper- of processes available for transforming crude into
ating costs. petroleum products such as: gasoline, diesel, and
Kumari and Mateen [2] presented a study, for jet fuel. In general, refineries fall into three cat-
maximizing the refinery profit the optimization of egories. The simplest is a topping plant, which
selected refinery configurations, particularly the consists only of a distillation unit and probably
residue processing schemes. All selected configu- a catalytic reformer to provide octane. The next
rations have “Zero Residue” and “Zero Fuel Oil” type of refining is a cracking refinery, which takes
refinery producing Euro IV specification fuels. El- the gas oil portion from the crude distillation unit
Temtamy and Gendy [3] studied seven different (a stream heavier than diesel fuel, but lighter than
schemes for the upgrading of atmospheric residue HFO) and breaks it down further into gasoline
produced in the Egyptian refineries. All the stud- and distillate components using catalysts, high
ied cases were identified as high diesel producing temperature and/or pressure. The third one of
alternatives. The discounted cash flow method refining is called the coking refinery. This refinery
was used for the economic evaluation of the stud- processes residual fuel, the heaviest material from
ied options. Sensitivity analyses have been per- the crude unit and thermally cracks it into lighter
formed on the most profitable scheme. They showed product in a coker or a hydrocracker. The addi-
that all methods of analyses showed that the prod- tion of a fluid catalytic cracking unit (FCCU) or
uct sales price is the most influential factor for the a hydrocracker significantly increases the yield of
project profitability. Carrillo and Corredor [4] vi- higher-value products like gasoline and diesel oil
sualized alternatives of producing synthetic crude from a barrel of crude. All investigated scenar-
from Castilla crude, compatible with the existing ios are shown in Table 2.1. A typical of refinery
technologies available in the refineries, at the low- configuration processes is shown in Figure 2.1.
est possible cost and with the best cost/benefit
ratio, using well-known technologies applied for 2.1. Catalytic Reforming Process
the heavy crude oil upgrading in both Orinoco Reforming is an oil refining operation that pro-
belt (Venezuela) and Alberta province (Canada). duces reformate, a high-octane gasoline blending
26
risks and uncertainties. Therefore, the economic
evaluation can be a main tool and reasonable way
to find out best petroleum investment opportuni-
ties in terms of cost, revenue and risks.
3.1. Factors Affecting Refinery Costs
Refining costs greatly depend on several factors:
• Refinery complexity
• Capacity utilization or stream factor
• Refinery size
• Quality of the crude
• Location
Figure 2.1: Refinery Configuration Process Scenario
(Sc2) • Environmental constraints
In the oil refining business, the cost of inputs
component. The reforming process uses heavy (crude oil) and the price of outputs (refined prod-
naphtha, which is the second lightest liquid stream ucts) are both highly volatile, influenced by global,
from an atmospheric distillation column, to pro- regional, and local supply and demand changes.
duce reformate. In the reforming complex, a feed The parameters will be take in account are: Prof-
pre-treater removes sulfur from the reformer feed itability, Return of Investment (ROI), Gross Mar-
using hydrogen and a desulfurization catalyst. The gin, Discounted Cash Flow,
pre-treated feed then is sent to the reformer reac- The payout time is also referred to as the cash re-
tor where a catalyst and heat are used to restruc- covery period or years to pay out. It is calculated
ture or reform low octane naphtha into higher by the following formula and is expressed to the
octane hydrocarbon molecules that are valuable nearest one-tenth year [7]:
gasoline blending components (see Figure 2.2).
The process turns straight-chain hydrocarbons into P ayouttime =(originaldepreciable
cyclic compounds while removing hydrogen. The
cyclic compounds have a much higher octane rat- f ixedinvestment)/ (3.1)
ing than the straight-chain feedstock and enable (AnnualCashf low)
economic production of high-octane lead-free gaso-
line.
4. Results and Discussion
In this work, the existing refinery configuration
(Sc1, 1125 bbl/day) and two upgrading scenar-
ios (Sc2 and Sc3) included the FCC and delayed
coking processes (Table 2.1) are simulated for re-
fining of 220,000 bbl/day of Sarir-Messla crude oil
Figure 2.2: Typical reforming process diagram (Source: which having a gravity of 37.6 °API (sp.gr 0.8368
U.S. Energy Information Administration) @ 15.6/15.6 °C), Sulphur content of 0.128 wt %
and the characterization factor of crude was cal-
culated to be 12.2. It has a pour point +15 °C
and a kinematic viscosity of 7.3991 and 6.2251
3. Refinery Economics CSt at 100 and 122 °F respectively. Sarir-Messla
crude oil has Nickel and Vanadium content of
Petroleum projects as investment opportunities
2.781 and 0.157 ppm respectively and conradson
require huge funds and with a long time to con-
carbon residue (CCR) content of 3.192 wt%.
struct and they are associated with a series of
27
4.1. Distillation and Analysis
The distillation of the sample was carried out in
two major steps as per ASTM D 2892 (15 The-
oretical plate column) & ASTM D-1160 method.
The atmospheric residue was further distilled to
obtain distillate fractions. Distillate fractions cor-
responding to true boiling point up to 550+°C
were collected. The yield pattern of each fraction
collected is tabulated in percentage weight and
percentage volume and has shown in Table 4.1.
4.2. Catalytic Reforming Material Balance Figure 4.1: Gasoline yield Reforming Unit Material Bal-
In this case, the feed to the catalytic reformer ance (Sc2& Sc3)
consists of the heavy straight-run (HSR) gaso-
line (70 to 175°C) from the atmospheric distilla-
tion unit (10364.5 lb/day). Yield correlations for refinery configuration and two scenarios schemes
the reformer were developed by Maples [6]. The under consideration are evaluated using the dis-
yields for the all products calculated based on the counting cash flow method. Feed and product
C5+ Vol. % correlation (Equation 5) which is de- prices for all units are shown in Table 4.5. Total
pended on assumption of RONR = 94 and N + capital cost ($) for each scenario can be summa-
2A = 44.7% respectively. rized in Table 4.3 while the details percentage (%)
parameters of total fixed cost for both FCC and
C5 + V ol. =142.7914 − .077033 ∗ RONR delayed coking unit was estimated based on total
(4.1)
+ 0.219122 ∗ (N + 2A)F capital cost and presented in Table 4.4 . Cumu-
Where RONR is research octane number of re- lative cash flow diagram for both scenario 2 and
formate; C5 Vol% is volume percent of reformate 3 are shown in Figure 4.2 and 4.3.
yield; N is Napthenes Vol. % and A is Aromatics It can be seen from Table 4.5 that, 13 % increasing
vol. % (subscript F mean in the feed). The mate- in total cash in Sc2 while 27.3 % increased for
rial balance for the reformer specific for gasoline Sc3 (less yield gasoline produced) compared with
yield (Sc2) is shown in Figure 4. The total gaso- the total capital cash in existing refinery process
line yield for each scenario can be summarized in (Sc1).
Table 4.2.
Table 4.4: Total fixed cost details for both FCC and
Table 4.2: Product Yield (%) for each Configuration delayed coking units
Product yield % Sc1 Sc2 Sc3 Parameter % (from
Capital cost)
Gasoline yield 14% 40% 17%
Depreciation 5%
Interest 3.5%
It can be seen from Table 4.2 that, scenario 2 (in-
Process unites maintenance 5%
cluded FCC unit) converted wide range of feed-
Off – sites maintenance 2.5%
stock from atmospheric and vacuum distillation
General plant overhead 2.0%
units to produce more gasoline yield compared
Taxes and insurance 2.5%
with scenario 3 which has the delayed coking pro-
cess. Furthermore in the existing refinery config-
uration the gasoline yield was found 14 %. It can be seen from Figure 5 that the payout time
for Sc2 was found between 3-4 years while in Fig-
4.3. Economic Evaluation for the Proposed ure 6 Sc3 (included delayed coking) was found
Scenarios between 4-5 years. That means Sc 2 better than
The profitability of an industrial opportunity is a Sc3 in terms of cash recovery.
function ofmajor economic variables such as prod-
uct selling price, raw materials prices, capital in-
vestment, energy prices and so on. The existing
28
Table 4.1: Summary of product cut points and yields
Cut Point °C Product Yield on Crude (Wt. %) Yield on Crude (Vol. %)
Gases& LPG 1.03 1.55
C5-70 Light Naphtha 5.6 7.18
70-175 Heavy Naphtha 16.07 17.94
175-235 Kerosene 9.31 9.82
235-350 Atm. Gas Oil 19.85 19.97
350-550 Vac. Gas Oil 31.18 29.37
550+ Vac. Residue 16.95 14.33
Table 4.3: Total Capital cost for each scenario
Scenario Total Capital Cost ($)
Sc1 3,081,737,888
Sc2 3,491,661,619
Sc3 3,924,552,788
Table 4.5: Prices of crude oil and products
Product Price ($/ton)
LPG 444
Figure 4.2: Cumulative Cash for diagram for Sc2
Light Naphtha (atm) 504
Heavy Naphtha (atm ) 510
Kerosene (atm) 529
Gasoil (Atm + V + FCC) 500
Gasoline (FCC) 546
C2& Lighter 100
Propane (C3) 345
Propylene (C3") 345
Butylene (C4") 277
H2 (lb/day) 400
Gas C4 (lb/day) 277
Coke 334
Crude oil price ($/bbl) 45 Figure 4.3: Cumulative Cash for diagram for Sc3
5. Conclusion coking process. Generally, each refinery’s config-
uration is determined primarily by the refinery’s
The purpose of refining is to convert natural raw location, preferred crude oil slate, market require-
materials such as crude oil into useful saleable ments, and quality specifications for refined prod-
product. A Comparison between the existing and ucts.
proposed upgrading refinery processes included
FCC or Delayed coking units in terms of techno-
economic feasibility study is the main outcome 6. Acknowledgment
of this work. Obtained results show that, the The authors gratefully acknowledge the financial
scenario which included the FCC unit has shown support given for this work by the NOC-Libya.
the best in terms of both gasoline production im-
proved by 28% and the capital cost decreased
by 12% compared with that included the delayed
29
References
[1] Asia-Pacific refining primed for capacity
growth, oil& gas journal, 2014, 34-45.
[2] Kalpana K. and Mateen A.Techno-economic
Study of Petroleum Refinery Configurations
for RasGharib Crude Oil.2013, 3, 43-48.
[3] El-Temtamy, S. A.; Gendy T. S. Economic
evaluation and sensitivity analysis of some fuel
oil upgrading processes.Egyptian Journal of
Petroleum. 2014,23,397-407.
[4] Carrillo, J. A.; Corredor, L. M. Upgrad-
ing of heavy crude oils: Castilla. Fuel Proc.
Tech..2013, 109,156–162.
[5] Gupta, R. K.; Gera, P. Process for the upgra-
dation of petroleum residue: Review. Inter-
national Journal of Advanced Technology in
Engineering and Science.2015, 3,643-656.
[6] Maples, R. E. Petroleum Refining Process
Economics. PennWell Book. 1993, Tulsa.
[7] Gary, J.; Handwerk, G. 4th, Petroleum Refin-
ing Technology and Economic. Marcel Dekker,
Inc. 2001, pp 357.
[8] Ghayth, A. M. Gasoline Upgrading: Techno-
economic Feasibility Study Based on Charac-
terization of LibyanCrude Oils, Msc. Thesis,
Libyan Academy,2014.
30
