Elaborate Design for Building Intrinsic Energy-saving Refineries
Elaborate Design, the Basis
for Building Intrinsic Energy-saving Refineries
SINOPEC Engineering Incorporation
Nov. 2008
Elaborate Design for Building Intrinsic Energy-saving Refineries
CONTENTS
1. Summary
2. Elaborate Design, the Basis for Building Intrinsic
Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.2 Optimization of Main Utility Scheme
2.3 Effective Energy-saving Measures
2.4 Analysis on Differences in Energy Consumption
3. Conclusion
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Elaborate Design for Building Intrinsic Energy-saving Refineries
1. Summary
¾New challenges to oil refining enterprises.
‹high oil price
‹the increasing market demand for oil products
¾The rapid growth of China’s GDP results in the increasing
market demand for transportation fuel.
¾Oil refining enterprises have to build resource-saving and
energy-saving refineries .
¾SEI always sticks to the principles of refinery construction
in the new century, i.e. advanced technology, reasonable
investment, resource conservation, energy consumption
reduction and good economic benefit.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2. Elaborate Design
for Building Intrinsic Energy-saving Refineries
The two typical refineries newly built in the 21st Century:
¾Refinery A processes Middle East sour crude with a sulfur
content of 1.0%. A CDU/VDU-RDS-RFCC/HCU based process
scheme is selected. Its light oil yield amounts to 81% and
comprehensive commodity rate reaches 93%. It was put into
operation in September 2006 and has run smoothly for two
years.
¾Refinery B processes a crude mixture of 50% AL and 50%
AH with a sulfur content of 2.56%. A CDU/VDU-DCU-HTUFCC is selected. Its light oil yield amounts to 76.1% and
comprehensive commodity rate reaches 90.6%. It was put into
operation in May 2008 and has run smoothly for several months.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2. Elaborate Design
for Building Intrinsic Energy-saving Refineries
¾In engineering design, an important objective of the research
on project scheme is energy conservation and consumption
reduction.
¾The analysis results show that the sum of energy consumption
of CDU/VDU, RFCCU, HTU and CCRU in Refinery A accounts
for 61.2%, while Refinery B holds a 65.4% in the same aspect.
¾The proportions of energy consumption of process units to
refinery-wide energy consumption in Refinery A and Refinery B
are 88.15% and 89.55%, respectively.
¾ Consumption of fuel, power and steam takes up 70~85% of the
refinery-wide energy consumption.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.1.1 The capacity of VDU, an accessory unit of CDU, should be
rationally determined to minimize the investment and the
energy consumption of unit.
2.1.2 Full advantages of RDS-RFCC combined process should
be taken to recycle the HCO from RFCC unit to RDS unit.
¾ A large amount of aromatics component in HCO can
dissolve the resin and asphaltene in residue. It improves
RDS reaction, reduces carbon deposit on catalyst, decreases
gas yield, and improves product distribution in HTU and
FCCU. Both the light oil yield and liquid yield of FCCU are
1.5~2wt% higher than those of the conventional process.
¾ Since less slurry and coke is produced in FCC unit, the
energy consumption of unit is lowered.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.1.3 Heat exchange network should be optimized to improve
the heat utilization efficiency.
¾The final temperature of heat exchange in CDU/VDU
might be above 300℃.
¾Multiple circulating refluxes are designed for the
fractionation tower in FCCU together with the features of
product distribution. High temperature slurry reflux is used
to generate MP steam in priority in catalyst cooler, while
other circulating refluxes are used as heat source for the
bottom reboilers in desorption tower and stabilizer, and
overhead circulating reflux and low temperature heat are
used as heat source for gas fractionation unit or deaerated
water preheating.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.1.4 Refinery-wide overhead gas should be collected for recovery,
and the flow direction of dry gas and LPG should be carefully
arranged.
¾A centralized light ends recovery facility is designed to
maximize the recovery of LPG products. It is estimated that
LPG recovery can be increased by 25,000~30,000 tons per
year. The recovery system can be located in combination with
CDU/VDU to fully utilize the low temperature heat.
¾Two trains of dry gas desulfurization are designed, one of
which treat FCC dry gas, then it is directly sent for rational
recovery and utilization of dilute ethylene byproduct.
¾Two or three trains of LPG desulfurization, one of which
treat FCC LPG, are designed to increase the additional value
of propylene product.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.1.5 Importance should be attached to hydrogen recovery, and
hydrogen resource should be allocated rationally.
¾ Both refineries have several large-scale HTUs. Low pressure
separator vapor from various units is collected to desulfur. Then
it is sent to PSA unit. About 10,000 tons of pure hydrogen can be
recovered per year. The pressurized PSA tail gas is used as feed
to the hydrogen plant.
¾According to the characteristics of hydrogen-consuming units
and their requirements, most of the hydrogen-containing gas
from CCRU is provided for HTU and SRU, while the rest is sent
to PSA unit together with hydrogen-containing gas for
purification. Pure hydrogen from PSA unit and from the
hydrogen plant is provided for RDSU and HCU. And there is a
connection line between the two hydrogen network to ensure the
safety of hydrogen use.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.1.6 A centralized amine regeneration system should be designed
for the refinery.
¾Two regeneration towers are designed to treat rich amine from
hydrogenation units and that from desulfurization units,
respectively. Regenerated lean amine is collected and sent to
amine-consuming units. Surge tank, which will be pressurized for
use, is designed according to the pressure requirements of each
unit.
¾Centralized administration can lower energy consumption,
avoid long-distance transportation, decrease the pressure loss of
hazardous high-concentration H2S inside the refinery, and
reduce the corrosion risk of pipelines.
¾The two regeneration towers match in capacity, and the two
solvent systems are connected to each other as mutual backup.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.1.7 Advanced energy-saving technologies should be adopted.
¾A combined vacuum system of steam vacuum pumping and
mechanical vacuum pumping is adopted as the overhead
vacuum system in large-scale VDUs. Compared with the steam
ejection vacuum pumping system, a consumption reduction of
0.5 kg oe/t of crude oil can be achieved, and the payback period
is only half a year.
¾Proprietary technologies or equipment, such as highefficiency atomizing nozzle, high-efficiency stripper and highefficiency cyclone, may be used in the reactor to improve
product distribution and reduce coke formation.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.1.7 Advanced energy-saving technologies should be adopted.
¾The pressure energy of high-pressure liquid in HTU may be
fully utilized to drive pumps. Hydrogen combined before
heater is applied to improve heat transfer efficiency, to reduce
the number of heat exchanger and to lower the pressure drop
across system.
¾Advanced furnace design methods are applied to delayed
coker to realize operation at low recycle ratio or even zero
recycle ratio to minimize the circulation.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.1 Optimization of Process Scheme and Selection of
Advanced Energy-saving Equipment
2.1.8 Advanced energy-saving equipment should be adopted.
¾Advanced feed distributor and corresponding internals may be
used in fractionation tower to minimize the consumption of
stripping steam.
¾AC and DC electric desalting technology or high velocity
electric desalting technology is adopted.
¾An innovative high-efficiency heat exchanger is adopted.
¾Energy-saving chemical process pump or high-efficiency
centrifugal pump, which is equipped with energy-saving motor, is
used.
¾Frequency control motor is selected for air coolers, in which the
quantity and temperature of process stream varies a lot, to save
power energy while ensuring a stable temperature after cooling.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.2 Optimization of Main Utility Scheme
2.2.1 Furnace design should be optimized to reduce fuel
consumption and improve thermal efficiency of furnace.
Consumption of furnace fuel accounts for about 40% of refinerywide energy consumption, so fuel saving is of great importance to
refinery-wide energy conservation.
¾Fuel system is optimized to supply clean furnace fuel. All the
fuel gas produced is desulfurized to reduce its H2S content to
less than 50ppm so that lowering flue gas temperature and
improving the thermal efficiency of furnace may become possible.
¾Energy-saving burner is adopted to expedite the burning rate
of fuel to realize forced convection by the high velocity and
uniform flow of flue gas. In this way the efficiency of furnace can
be increased by 2%.
¾Effective waste heat recovery facilities are designed for the
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furnace to improve its thermal efficiency.
Elaborate Design for Building Intrinsic Energy-saving Refineries
2.2 Optimization of Main Utility Scheme
2.2.2 Hot feed and heat integration of units should be realized to
reduce heat loss.
¾Integrated units are designed for main process units according
to the closeness requirements of their functions and materials.
Only 4 integrated units are planned for the 15 main process units
in both refineries. The best heat utilization scheme is to optimize
the integrated heat exchange of materials from various units and
select reasonable inlet/outlet temperatures. The capacity of
intermediate tank farm can only ensure 2 days’ operation of
downstream units. There is one central control room in the
refinery, which has features of distributed control, centralized
operation and centralized management.
¾Heat integration is realized between units which have a close
relationship with each other. For example, the overhead waste
heat from FCC fractionator is used as heat source for gas
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fractionation unit.
Elaborate Design for Building Intrinsic Energy-saving Refineries
2.2 Optimization of Main Utility Scheme
2.2.3 Low temperature heat should be fully utilized to further
reduce energy consumption.
Low temperature heat in process units is used to heat boiler feed
water. However, no other low temperature hot trap is available
for refining systems, so low temperature heat is not fully utilized.
Utilization method and technology of low temperature heat is to
be further studied and developed.
2.2.4 Steam system in refinery should be optimized to improve
steam utilization and reduce steam consumption.
Firstly, cascade utilization of steam should be realized. Secondly,
power generation should be determined by steam demand.
Thirdly, steam leakage should be minimized. High quality valves
and steam traps should be used on steam pipelines to minimize
steam leakage.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.2 Optimization of Main Utility Scheme
2.2.5 Effective water saving measures should be taken.
¾Consumption of fresh water should be minimized, circulating
water is used as feed water to blow down cooling tank and water
tank, and effluent is sent to force circulation hot water piping
system after being pressurized via a pump.
¾Purified water reuse rate should be improved.
¾Wastewater reuse rate should be improved.
¾Condensate reuse rate should be improved. A centralized
condensate recovery network and treatment facilities are
designed for the refinery to recover, treat and utilize refinerywide turbine condensate and condensate formed in the heating
and heat tracing of process units. The recovery of condensate is
above 80%.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.3 Effective Energy-saving Measures
for Good Energy-saving Results
¾Attention has been paid to the application of new energy-saving
technologies and the adoption of advanced energy-saving equipment.
In this way, design energy consumption of production units attained
world advanced level, and design refinery-wide energy consumption
was remarkably reduced.
¾The design energy consumption of process units in the two refineries
varies from unit to unit because of different feedstock property,
process condition and scope of design, but the design energy
consumption of almost all the units meet or are even lower than the
energy consumption quota stipulated by SINOPEC.
¾Operation data show that both the energy consumption of main units
and the refinery are lower than the design value, indicating that the
energy consumption can be further reduced by optimizing the
operation of production units.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.4 Analysis on Differences in Energy Consumption
¾The design energy consumption of each unit meets or is
even lower than the energy consumption quota stipulated by
SINOPEC
¾The comprehensive energy consumption is higher than the
statistical energy consumption of advanced energy-saving
enterprises in SINOPEC, especially the new energy
consumption target of SINOPEC (65 kg oe/t of crude oil).
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Elaborate Design for Building Intrinsic Energy-saving Refineries
2.4 Analysis on Difference in Energy Consumption
The reasons are list below:
¾The complexity of process flow is one of the reasons for
high comprehensive energy consumption.
¾Poor quality crude oil processing increases refinery-wide
energy consumption.
¾Design data are selected based on the worst conditions, so
design energy consumption is higher than actual energy
consumption.
¾Conditions for larger scale systematic optimization are
unavailable.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
3. Conclusion
¾The launch of a movement for effective energy-saving is an arduous,
complicated and painstaking task.
¾The subject of our study has already moved from energy
optimization of a single unit to integrated optimization of the whole
refinery.
¾Energy conservation of utility system should also be emphasized
while paying attention to the energy conservation of process units, and
researches and development of low temperature heat resource
recovery and utilization technology should be strengthened.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
3. Conclusion
¾ Analysis on energy consumption of above-mentioned typical
grassroots refineries shows that the key to energy consumption
reduction is the optimization of overall process scheme and
adjustment in unit configuration.
¾ The proportion of steam and power consumption to energy
consumption is relatively high, so optimizing steam and power
balance is an effective measure for energy conservation.
¾ In future, we will further implement the incentive mechanism for
energy conservation based on the achievements we have already made,
and put a lot of work in both administration and technology to carry
out energy conservation and effective utilization of resources into each
link of project planning and engineering. Meanwhile, we will pay
further attention to energy-saving technology and administration in
actual operation so as to build intrinsic energy-saving refineries.
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Elaborate Design for Building Intrinsic Energy-saving Refineries
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