gas & coal oxy-combustion feasibility studies · case 1. oxy-fired usc pc key design features...

© 2016 Electric Power Research Institute, Inc. All rights reserved.

George Booras

Principal Technical Leader

P66 Advisory Meeting

Orlando, FL

September 13, 2016

Gas & Coal Oxy-Combustion

Feasibility StudiesInterim Results

2© 2016 Electric Power Research Institute, Inc. All rights reserved.

Detailed Economic Feasibility Study of

Advanced Fossil Power

Detailed engineering-economic feasibility study of atmospheric pressure Oxy-Fired USC PC Plant with CO2 capture

Essentially an update of EPRI Report 1021782, Aug. 2011

‒ Nominal 700 MW plant size

‒ 600⁰C steam conditions with PRB coal

Includes Oxy-Fired Natural Gas Cases

‒ Cases similar to those in 2015 IEA GHG Report by Amec Foster Wheeler

‒ Cycles using recycled CO2

‒ Semi-Closed Oxy-Combustion Combined Cycle (SCOC-CC)

‒ NET Power – Allam Cycle

‒ Cycles using mainly H2O

‒ Modified S-Graz Cycle

‒ Clean Energy Systems (CES)

Report to be published December 2016 (3002008148)


Study Cases

Number Coal Steam Conditions Plant Net Power CO2 Capture

1 PRB 600°C / 620°C 700 MWe 90%

Number Description Plant thermal input CO2 capture

2 Semi-Closed Oxy-Combustion

Combined Cycle (SCOC-CC)

2 x 620 MWth

(Equivalent to 2 F-class gas

turbines, suitable for 60 Hz)

90%

3 NET Power – Allam Cycle Same thermal input of case 2 90%

4 Modified S-Graz Cycle Same thermal input of case 2 90%

5 Clean Energy Systems (CES) Same thermal input of case 2 90%


Main Design Basis

The site location is Kenosha, Wisconsin, a greenfield site typical of power

generation facilities located in Middle America and having access to water and

rail transportation, with a reference ambient temperature of 15°C (59°F).

The plant has access to raw water, mainly used as make-up water for the

cooling water system (based on forced draft cooling towers).

The steam turbine is designed to operate in normal conditions with an exhaust

steam condensing pressure of 0.0677 bara (2” Hg), corresponding to 38.4°C

(101°F).

CO2 capture rate is set to 90% for all the cases. CO2 is delivered at plant BL at

the supercritical conditions (152 barg, 30°C) and purity >99.0% wt (< 0.1 ppmv

moisture content)


Case 1. Oxy-fired USC PCMain Design Basis

The as-received PRB coal has the following main characteristics:

– Moisture = 30.2 wt %

– Ash = 5.3 wt %

– Sulfur = 0.37 wt %

– Heating Value (HHV) = 8,340 Btu/lb (19.4 MJ/kg)

The ultra-supercritical steam conditions are:

‒ Main steam: 290 bar / 600 °C (4200 psi / 1110°F)

‒ Reheat steam: 60 bar / 620 °C (870 psi / 1150°F)

‒ Condenser pressure = 2.0 in. Hg (0.0677 bar)

Generic low pressure pumped oxygen air separation unit,

– Oxygen purity = 97% by vol.

Combustion efficiency = 92% (LHV basis)


Case 1. Oxy-fired USC PCBlock Flow Diagram


Case 1. Oxy-fired USC PCKey Design Features

Two streams of recycle flue gas are required for the oxy-combustion system.

– The Primary recycle stream, taken downstream the final contact cooler,

which passes through the coal mills, is used for drying and transportation

of the pulverized fuel to the burners.

– The Secondary recycle stream, taken downstream the fabric filter,

provides the additional gas heat capacity to the burners to maintain

temperatures within the furnace similar to those of air firing boilers.

The combined primary and secondary gas recycle is approximately 69% of

the original flue gas leaving the economizer.


Case 1. Oxy-fired USC PCUSC PC Boiler Scheme

(*) as % wt of the flue gas leaving the economizer


Case 1. Oxy-fired USC PCKey Design Features

CO2 Purification Unit is based on sour compression technology for nitrogen oxide

removal and auto-refrigerated technology for inerts removal. Three flash vessel

are required to meet 90% CO2 capture at required purity (99% wt min)

De-SOx is not required to meet emission limits as sulfur oxides (SOx) are

removed in the compression section of the CO2 purification unit as sulfuric acid.

In oxy-combustion plant, a small FGD could be required to lower the sulfur

content in the furnace and limit corrosion issues. However, in the specific study

case, firing PRB, the sulfur content in the furnace recirculation remains below

2000 ppm normally considered as the threshold level for the corrosion issues.

De-NOx is not required as nitrogen oxides (NOx) are removed in the

compression section of the CO2 purification unit as nitric acid.


Case 1. Oxy-fired USC PCPerformance Summary

(1) including step-up transformer losses

Case 1

USC PC Boiler

Coal flowrate k lb/h 940.1

Thermal input (LHV/HHV basis) MWth 2,125 / 2,298

Gross Electric Power Output MWe 1,010.8

Auxiliary power demand (1) MWe 297.2

Net Electric Power Output MWe 713.6

Net Electrical Efficiency (LHV/HHV basis) % 33.6 / 31.1

Net Plant Heat Rate (LHV/HHV basis) Btu/kWh 10,158 / 10,974

CO2 removal efficiency % 90.1

Fuel consumption per net power production MWth / MWe 2.98

CO2 emission per net power production kg/MWh 104.1

CO2 emission per net power production lb/MWh 229.4


Case 2, 3, 4, 5. Oxy-fired TurbineMain Design Basis

Natural gas, available at 35 bar, has a heating value of 47.9 MJ/kg (LHV)

and a total inert content (nitrogen, CO2) lower than 2%.

Plant capacity is selected in order to fully load two gas turbines, equivalent to

the commercially available, air-fired, heavy duty F-class turbine, in terms of

thermal duty, mass flowrates and temperature profile.

3% oxygen excess in the combustion chamber, accounting also the oxygen

in the recycle gas

Pressure ratio is fixed in order to keep the same temperature increase

through the compressor of the reference air blown plant (SCOC-CC, S-Graz)


Case 2, 3, 4, 5. Oxy-fired TurbineTurbine Design Parameters Definition

Combustor outlet temperature (COT): Flue gas temperature at combustor outlet

Turbine inlet temperature (TIT): Flue gas total temperature at first gas turbine stator outlet,

after mixing with the first cooling flow.

Turbine outlet temperature (TOT): Flue gas temperature at gas turbine expander outlet

Pressure ratio: ratio between that gas turbine compressor outlet pressure (P1) and the

compressor inlet pressure (P0)

NATURAL GAS

OXYGEN

RECYCLE GAS FLUE GAS

TIT

COT

first stator

Pressure ratio = P1/P0

P0

P1

TOT


Case 2. SCOC-CCMain Design Basis

Power island including:

– Two F-class equivalent oxy-fired gas turbines

– Two heat recovery steam generators (HRSG), generating steam at two levels of

pressure, plus a LP integrated deaerator:

– Two recycle gas indirect contact cooling systems

– One steam turbine, water-cooled and condensing type, common to the two parallel trains

Turbine parameters as detailed below:

– Combustor outlet temperature: 1530°C

– Maximum allowable metal temperature: 860/830 °C (1st / other stator), 830/800 °C (1st /

other rotor)

– Expander inlet pressure: 45 bar (NG compressor required)

Generic low pressure air separation unit, producing 97 % vol purity oxygen at 55 bar

CO2 Purification Unit, including sour gas compression and purification, TSA, auto-

refrigerated Inerts Removal section and final CO2 compression. Three flash vessel process

is required to meet 90% CO2 capture at required purity (99% wt min)


Case 2. SCOC-CCPower Island Scheme

NG

Gas Turbine

O2

HRSG

ST

Waste Water

CO2 to CPU

1,529°C (2,784°F)

45 bar (650 psi)

1.06 bar (15.4 psi)

610°C (1,130°F)

NG Compressor

Condenser

0.0677 bar

(2” Hg)


Case 3. NET Power CycleMain Design Basis

Plant based on two power and CO2 cycles, each including:

– One oxy-combustion direct-fired CO2 turbine

– One main heat exchanger (MHE), for recycled gas pre-heating, compact multi-channel

plate-fin type

– One recycled gas compression loop

– NG compressor

Turbine parameters as detailed below:

– Combustor outlet temperature: 1150 °C

– Maximum allowable metal temperature: 860 °C

– Expander inlet pressure: 300 bar / expander outlet pressure: 34 bar

Generic low pressure air separation unit, producing 99.5% vol purity oxygen at 120 bar

CO2 Purification Unit, including TSA, auto-refrigerated Inerts Removal section and final CO2

compression. Two flash vessels are required to meet 90% CO2 capture at required purity

(99% wt min)


Case 3. NET Power CyclePower and CO2 Cycle Scheme

NG

sCO2 turbine

300 bar (4,350 psi)

1,150°C (2,102°F)

34 bar (490 psi)

740°C (1,365 °F)O2

CO2 to CPU

< 400°C

(< 750°F)718°C

(1,325°F)

Heat input from

ASU air compressor

O2 +

CO2

CO2

Waste Water

NG Compressor

CoolerCooler

Recycle stream

80 bar

(1,160 psi)

100 - 120 bar

(1,450 - 1,740 psi)


Case 4. Modified S-Graz CycleMain Design Basis

Power island composed by two trains, each including:

– One F-class equivalent oxy-fired gas turbine

– One heat recovery steam generator (HRSG) generating steam at one pressure level

– One back pressure steam turbine expanding the steam to the pressure level required for turbine blade

cooling (HPT)

– Wet flue gas compression and low pressure steam turbine (LPT)

– Recycled gas compression train (part of the gas turbine package)

Turbine parameters as detailed below, in line with SCOC-CC:

– Combustor outlet temperature: 1530 °C

– Maximum allowable metal temperature: 860/830°C (1st / other stator), 830/800°C (1st / other rotor)

– Expander inlet pressure: 45 bar (NG compressor required)


CO2 Purification Unit, including sour gas compression and purification, TSA, auto-refrigerated Inerts

Removal section and final CO2 compression. Three flash vessel process is required to meet 90% CO2

capture at required purity (99% wt min)


Case 4. Modified S-Graz CyclePower Island Scheme

O2NG

HPT

HRSG

HHT

CO2 to CPU

Steam

LPT

WaterWaste Water

45 bar (650 psi)

1,529 °C (2,785°F)

1.05 bar

(15.2 psi)

170 bar (2,465 psi)

550°C (1,022°F)

90% steam

10% CO2

NG Compressor

Condenser

Recycle flue gas Flue gas

BFW

0.0677 bar

(2” Hg)

538 °C

(1,000°F)


Case 5. Supercritical CESMain Design Basis

Power island composed by two trains, each including:

– One F-class equivalent oxy-fired gas turbine, composed of:

• HP turbine (HPT): combustor and expansion section

• MP turbine (MPT): combustor and expansion section

• LP turbine (LPT): combustor and expansion section.

– One flue gas condenser at vacuum conditions

– Wet flue gas compressor.

– BFW/Steam system for combustor and HPT cooling (steam generated at

supercritical conditions, 350 bar, 650°C)


CO2 Purification Unit, including sour gas compression and purification, TSA, auto-

refrigerated Inerts Removal section and final CO2 compression. Three flash vessels

are required to meet 90% CO2 capture at required purity (99% wt min)


Case 5. Supercritical CESMain Design Basis

HP Turbine parameters as detailed below, in line with NET Power:


– Maximum allowable metal temperature: 860°C

– Expander inlet pressure: 300 bar / expander outlet pressure: 60 bar

MP/LP Turbine parameters as detailed below, in line with SCOC-CC:


– Maximum allowable metal temperature: 860/830°C (1st / other stator),

830/800°C (1st / other rotor)

– MP/LP Expander inlet pressure: 58.5 bar / 7.6 bar


Case 5. Supercritical CESPower Island Scheme

O2

NG

MPTHPT

CO2 to CPU

Steam

LPT

BFW

Waste Water

300 bar (4,350 psi)

1,150 °C (2,102 °F)

58.5 bar

(848 psi)

7.6 bar

(110 psi)

0.17 bar

(2.5 psi)

NG Compressor

O2 Compressor~23%* ~34%* ~43%*

(*) % wt of the total NG flowrate


Performance Summary

(1) including step-up transformer losses

OVERALL PERFORMANCECase 2

SCOC-CC

Case 3

NET Power Cycle

Case 4

Modified S-Graz

Cycle

Case 5

Supercritical CES

Cycle

Natural gas flowrate k lb/h 205.6 205.6 205.6 205.6

Thermal input (LHV/HHV basis) MWth 1,240 / 1,373 1,240 / 1,373 1,240 / 1,373 1,240 / 1,373

Gross Electric Power Output MWe 763.6 850 791.4 812

Auxiliary power demand (1) MWe 179.2 185.8 204.1 215.9

Net Electric Power Output MWe 584.4 664.2 587.4 596.1

Net Efficiency (LHV/HHV basis) % 47.1 / 42.5 53.6 / 48.4 47.4 / 42.8 48.1 / 43.4

Net Heat Rate (LHV/HHV basis) Btu/kWh 7,246 / 8,026 6,368 / 7,052 7,200 / 7,975 7,096 / 7,859

CO2 removal rate % 90.4 90.1 90.2 90.2

Fuel consumption per net power

production MWth/MWe 2.12 1.87 2.11 2.08

CO2 emission per net power production kg/MWh 40.9 37.4 41.8 41.7

CO2 emission per net power production lb/MWh 90.1 82.5 92.1 91.9


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gas & coal oxy-combustion feasibility studies · case 1. oxy-fired usc pc key design features...

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