Download CHENG Jian Pre-combustion CO2 capthre Aug. 16 2012

Pre-combustion CO2 capthre
CHENG Jian
Aug. 16 2012
Content
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Climate change
CCS method
Pre-combustion system introduction
Pre-combustion process selection
Pre-combustion system design
System energy comsumption
Climate change
Global average temperature is ascending obviously. It caused by greenhouse.
Climate change
• The aggravation of global warming is caused by intensifying
greenhouse effect.
• The radiation intensity of CO2rose by more than 20%
between1995 and 2005, the highest speed during the past 200
years.
• The greenhouse effect caused by CO2 accounts for 77% of all
greenhouse gases.
• Control of CO2emission is the key issue in tackling climate change!
Climate change
• Change the fuel used in power plant, for example develop
nuclear power, hydro power, natural gas and renewable
energy (wind, biomass, solar…)
• Improve the plant efficiency (use large scale SC/USC units and
IGCC units).
• Carbon capture and storage (CCS).
CO2 capture technologies
Pre-combustion capture
Post –combustion capture
CO2 capture
CO2 storage
CCS in Huaneng GroupS
•Chinese coal-based
energy structure will not
change in the long term.
•Power generation is the
primary CO2 emission
source. It accounts for
about 50％of the total
emission in China, and will
increase in the future.
•Huaneng Group develop
clean energy and CCS
technologies to face the
climate challenge .
CCS in Huaneng Group
120,000t/a CCS system in Shanghai
Shidongkou power plant
3000t post-combustion CCS system in
Beijing power plant
CCS in Huaneng Group
• CO2 concentrations in a coal –fired power station is 12% ~ 14%, the
pressure is 1 atm., so capture method only select MEA chemical
absorption method is fit for post-combustion power plant. It need a lot of
solvent and much steam to capture CO2, so the energy consumption for
post-combustion will be very great.
• Pre-combustion CO2 capture due to the high CO2 concentrations and high
total pressure, this make the use of physical absorption method for
trapping, pre-combustion capture CO2 has certain advantages in energy
consumption, so pre-combustion method is more prominent than the
post-combustion method.
• Huaneng Group planed to develop pre-combustion technologies and set
up a 30MW th pre-combustion system.
CCS in Huaneng Group
Pre-combustion
CO2 capture system
CCS in Huaneng Group
The first 250MWe
IGCC demonstration
power plant was built in
Tianjin; a 30MWth precombustion CO2 capture
and storage system will
be built on the basis of
the demo IGCC plant .
CCS in Huaneng Group
CO2 compress and transport to oil well for EOR and storage
Pre-combustion system
Air
Coal
Air
Seperation
O2
Syngas
N2,Ar
High Tem.
Clean up
Gasification
Commercial
building
Heat/power/cool
cogeneration
residential
petroleum
coke and
residue
Steam
NG
IGCC
or GCC
Shift
chemical
products
CO2+H2
Seperation
Liquid
fuel
CO2
H2
others
Heat/power/coal
cogeneration
Large-scale
power
generation
Fuel
cell
Sequestration
Dry
ice
fertilizer
algae
plant
growth
A pre-combustion system must be set up based on a gasifier.
enhancement
of CBM
Pre-combustion system
A pre-combustion CCS system includes:
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Water–gas shift
Desulfurization
Decarburization and H2 seperation
purify CO2 to industry stage
CO2 compress and transport
CO2 inject into oil well
CO2 capture rate and energy consumption must be
considered in the system design.
Water- gas shift process
CO+ H2O
CO2+H2+Q
工艺流程中应考虑的问题：
分段和段间降温方式
1、根据原料气co含量,满足变换率的要求
2、防止催化剂超温
3、反应余热的充分利用，
达到催化剂反应温度降低能耗
4、蒸气的回收和利用
降低外供蒸汽消耗
5、延长催化剂寿命
介质的净化
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Water- gas shift process
Desulfurization
• The Rectisol is a physical absorption method. The 1m3 solvent
can absorb 160 ~ 180m3 CO2 at 3.0MPa pressure so solution
cycle is .
• Simultaneous removal of impurities such as CO2, H2S and COS,
CO2select absorbent strong and H2S, high degree of purification.
• The disadvantage is operating under a low temperature of -40
℃, so low temperature materials is required, so the system
investment maybe higher.
Desulfurization
• MDEA is a good method to absorb CO2 and H2S.
• H2S is priority selected to removal to a few ppm.
• 1% -5% of the activated MDEA CO2 can remove CO2 and
H2S at the same time.
• Low energy consumption, generally 1.6-2.OkJ/Nm3.C02;
• less investment in equipment;
Desulfurization and carbon capture
Desulfurization and carbon capture
Desulfurization and carbon capture
• Common MDEA process: CO2 with H2S to the tarch is
around 26.4% of shifting gas CO2 。
• Common MDEA carbon capture with PSA: MDEA CO2
capture ratio is only around 66%。
• MDEA H2S-CO2 co-removal: CO2 capture ratio will
reach 90%
• Thus, H2S-CO2 co-removal process is one of best
options for pre-combustion CO2 capture
Energy concumption
项目
单位
单位折能MJ
MDEA消耗
硫碳共脱消耗
5.66
1.95
中压蒸汽
t/h
2793
低压蒸汽
t/h
2754
电
kWh
11.84
1723
1755
锅炉给水
t/h
28.470
1.566
1.5
冷却水
t/h
2.512
498
605
产品氢气
Nm3/h
10.79
－6941
－7100
变换回收热量
GJ
10. 54
10.54
合成气
Nm3/h
10000
10000
产品CO2
万吨/年
6.12
7.35
操作时间
8000h
9.45
4.5
Energy consumption
• Energy consumption for common MDEA desulfurization with
pressure swing adsorption CO2 capture is around
6.08GJ/tCO2,
• H2S-CO2 co-removal: 5.17GJ/tCO2，
• Energy consumption gradually increase with CO2 capture ratio
• Comparison: Huaneng Beijing Thermal Power Plant Post
combustion CO2 capture, steam energy consumption
3.6GJ/tCO2, power 75KW , CO2 compression and refining
175kW，Total energy consumption 6.55GJ/tCO2。
Energy consumption
• However, since pre-combustion CO2 capture have longer
process, with shifting reaction, desulfurization, carbon
capture and CO2 compression
• If one would like compare the energy consumption between
pre-combustion CO2 capture and post-combustion CO2
capture, we need to remove the MDEA desulfurization energy
cost
Energy consumption
• Thus, we can get pre-combustion CO2 capture
energy consumption at 2.50GJ/tCO2, which is
far lower than post-combustion CO2 capture
• From the simulation, it can be indicated that
the energy consumption CO2 capture energy
consumption can be further lowered by full
utilize the shifting process waste heat and to
reduce the steam consumption