Five Gasifiers
Optimization of IGCC power plant
Samantha Chase
David Granum
Ming Chen Tang
Irena Vankova
Sung Yoon
Project Definition
 Improvements to existing Integrated Gasification Combined Cycle (IGCC)
 Optimize an air separation unit (ASU)
Decrease energy consumption in the current simulation
Develop air separation alternatives
 Minimize water usage in the overall process
Decrease water requirements in the current simulation
Suggest cooling alternatives
Integrated Gasification Combined Cycle
AIR
POWER
GENERATION
AIR SEPARATION
NITROGEN
ELECTRICITY
OXYGEN
COAL
GASIFICATION
Ignition
SYNGAS
Outline
 Air separation unit optimization

Optimization of existing unit

Cryogenic air separation alternatives

Non-cryogenic air separation alternatives
 Water usage minimization

Water usage analysis

Process cooling alternatives
 Economics

ASU comparison

Water versus air cooling
 Environmental permitting
 Future work
Optimization of the Air
Separation Unit
38.5 MW
60 MW
B3
B1
B1
B4
B1
Inlet Air Compression
0.85 atm
9.19 atm
4.42 atm
12.0 MW
16.5 MW
O2 Product Stream
-167 °C 4.42 atm
-176 °C 2.18 atm
B1
O2 Compression
12.3 MW
N2 Product Stream
-180 °C 4.42 atm
-188 °C 2.18 atm
B1
N2 Compression
N2
2.13 atm 37.5 °C
12.04 atm
430 °C
B1
259 MW
B1
B1
AIR
SYNGAS
19.73 atm 40 °C
12.04 atm
1310 °C
B5
N2
20.07 atm 167 °C
12.04 atm
1410 °C
B1
219 MW
5.06 atm
1052 °C
215.2 MW
2.13 atm
761 °C
192.84MW
0.90 atm
579 °C
159.4 MW
5.06 atm
1139 °C
207.7 MW
2.13 atm
906 °C
173.7 MW
0.90 atm
561 °C
157 MW
Overall Results
 ASU electricity improvements:
 Original ASU electricity usage: -85.0 MW
 New ASU electricity usage: -54.6 MW
 30.4 MW Improvement
 Gas turbine improvements:
 Original electricity production: 309 MW

New electricity production: 319 MW
 10.0 MW improvement
 Overall: 40.4 MW Improvement
 407 MW
447.4 MW sent to grid
Alternative Energy Source
 Wind Synergy
 Adjacent Wind Farm
 Wind turbines that
send electricity to a
power grid
Millions of dollars
 Wind turbines to
power compressors
Fixed Capital Cost
800
700
600
500
400
300
200
100
0
748
394
305
Original
Improved
Wind
Ion Transport Membrane (ITM)
 Novel technology – Air Products, Praxair
 Pilot plant 5 TPD of O2
 Mixed conducting non-porous ceramic membranes
 100% oxygen selectivity
 Single stage air separation – compact design
 Savings on the ASU
 35% on capital cost
 37% on power requirements
 Easy integration into the current process
800-900 °C
High Partial Pressure
Low Partial Pressure
Minimization of Water Usage
Water Profile by Block
AIR
SEPARATION
UNIT
Moisture in Air
Moisture in Vent
Boiling Feed Water
Nitrogen
Oxygen
Moisture in Coal (28%)
GASIFIER
Syngas
GAS
TURBINE
Exhausted Flue Gas
Slurry Makeup
Moisture in Cooling Air
Cooling Water Makeup
COOLING
TOWER
Cooling Water Blowdown
Cooling Water Evaporation
STEAM
GENERATION
Overall Water Balance
WATER IN
Location
Raw Water
Syngas Combustion in Gas Turbine
WATER OUT
Flow Rate
(m3/hr)
997
Location
Flow Rate (m3/hr)
Ash Handling Blowdown
2.2
Water with Slag
0
Water Loss in COS Hydrolysis
0.01
Sour Water Blowdown
0.1
Cooling Tower Blowdown
185
Cooling Tower Evaporation
809
Gas Turbine Flue Gas
220
218
Combustion Air for Gas Turbine
1.3
Moisture in Coal
53
Water Lost in Gasification
53
Air Moisture to ASU
0.5
Moisture from ASU Vent
0.5
TOTAL
1269
TOTAL
1269
Raw Water Feed to the Plant
4% 1%
Makeup to Cooling Tower
12%
Boiling Feed Water
83%
Makeup to Slurry System
Moisture in Air to Cooling Tower
Water Usage and Heat Exchanger
 Why? Most of water for heat exchanger
 Shell-and-tube exchanger (default)
ROBUST!
WATERCONSUMING…
Air Fin – Cooling Alternative
 Atmospheric air is a cooling medium
Economics
Basis for Economic Evaluation
 Project period: 20 years
 Discount factor: 10%
 Inflation: 4%
 Installation factor: 504%
 Working capital: 20% of fixed capital investment (FCI)
 Tax rate: 35%
 Costs: positive
 Disregard constants common for all alternatives
 e.g. Oxygen product constant for all ASUs
 Compare net present values (NPV)
 No internal rate of return (IRR) or payback period
ASU Capital Cost Comparison
Improved
Original
Cost in millions of dollars
50
42
40
31
30
20
16
19
6
10
8
2
2
0
Towers
Heatex
Heaters
Compressors
ASU Utility Cost Comparison
Cost in millions of dollars /year
Improved
35
40
30
Original
23
20
10
0
0
2
0
Electricity
Cooling water
Steam
3
NPV10 Sensitivity – ASU Capital Cost
Original
Improved
1.8
1.66
Billions of dollars
1.6
1.43
1.4
1.2
1.21
1.02
1
0.8
1.17
0.88
0.6
100.00%
150.00%
200.00%
NPV10 Sensitivity – ASU Utility Cost
Original
Improved
1.8
Billions of dollars
1.6
1.58
1.4
1.2
1.21
1
0.8
0.88
0.6
100.00%
1.28
1.36
1.17
0.94
1.00
150.00%
Evaluation of Cooling Alternatives
 Compare original (shell-and-tube) with alternative (air fin) case
 Estimate economical effect of replacement of heat exchanger
 Procedure
1) Estimate cash flow for original case
2) Do same things for alternative case
3) Construct incremental cash flow (CF) for every year:
𝑖𝑛𝑐𝑟𝑒𝑚𝑒𝑛𝑡𝑎𝑙 𝐶𝐹𝑖 = 𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝐶𝐹𝑖 − (𝑎𝑙𝑡𝑒𝑟𝑛𝑎𝑡𝑖𝑣𝑒 𝐶𝐹𝑖 )
4) Calculate net present value (NPV)
5) Estimation: if NPV is positive, original requires less cost; if NPV is negative,
alternative is more economically reliable
Shell-and-Tube vs. Air Fin – Econ Analysis
Shell-and-Tube
Fixed Capital Investment
Variable Cost
Air Fin
$ 1,900,000
$ 8,800,000
$ 400,000
$0
 Construct incremental cash flow (CF):
1) Case 01: Incremental CF = Shell-and-Tube CF – Air Fin CF
2) Case 02: Incremental CF = Air Fin CF – Shell-and-Tube CF
Case 01 (CW)
NPV10
$ 1,800,000
Case 02 (AF)
- $ 1,800,000
Environmental Permitting
 Solid Waste-permit acquired through Wyoming’s DEQ Solid & Hazardous
Waste Division
 Sludge is regulated as ‘solid waste’; products of SO2, Hg, and acid gas removal ‘hazardous
waste’
 Air Emissions-Title V operating permit acquired through DEQ Air Quality
Division
 Process meets all emission regulations for coal plants
0.0008 lb SO2<< 0.3 lb SO2/ 106 BTU
 Recently (March 2011), EPA announced it will regulate mercury and acid gas in coal
State of Wyoming is currently suing the EPA
 Potential for future CO2 regulations
Process contains CO2 removal and compression unit
Conclusions & Future Work
 Conclusions
 Improved cryogenic ASU design
 Air fins instead of water cooling
 Suggestions for future work
 Heat integration
 Continue to monitor ASU technology improvements
Argon separation
Membrane separation