Post-combustion CO2 capture from natural gas combined cycles by solvent supported membranes - presentation by Matteo Romano of Politecnico di Milano at the UKCCSRC Natural Gas CCS Network Meeting at GHGT-12, Austin, Texas, October 2014

1. Post-combustion CO2 capture from natural gas combined cycles by solvent supported membranes
Alberto Volenoa, Matteo C. Romanoa, Davide M. Turia, Paolo Chiesaa,
Minh T. Hob, Dianne E. Wileyb
a Politecnico di Milano, Department of Energy, Milan, Italy
b CO2CRC, University of New South Wales, Sydney, Australia
GHGT-12, Austin, TX, USA – 6-9th October 2014

2. 2
Integration in NG combined cycles
NGCC flue gas:
•
CO2 concentration ~ 4%
•
N2/CO2 ~ 19  large surface and low CO2 purity with a simple post- combustion capture configuration
NGCC with flue gas recycle:
•
CO2 concentration ~ 8-10%
•
N2/CO2 ~ 10  smaller surface, but still low CO2 purity (purification step required)

3. 3
Integration in NG combined cycles
Alternative configuration with selective CO2 flue gas recycle
Merkel TC, Lin H, Wei X, Baker R. J Membr Sci 2010;359:126-139.
e.me.mCO2CO2Flue gas ventedair / flue gasfuelCO2water/steam~ Gas turbineSteam turbineHRSG~ HPevaIPevaLPecoIPrhHP sh IPecoHPecoIPshHPecoLPevaLPshmemb. 2memb. 1CO2to storageNatural gasFlue gas coolere.m
At memb.1 inlet:
•
CO2 concentration ~ 33-35%
•
N2/CO2 ~ 1.7

4. 4
Results
Sensitivity analysis on membrane feed pressure:
Ref. NGCC Membrane cases Membrane feed pressure, bar 1.52 2.03 3.04 4.05 Power balance, MW: Gas turbine net power 272.1 249.8 249.4 249.2 249.0 Steam turbine gross power 147.1 167.3 167.6 167.7 168.0 Steam cycle pumps -1.79 -2.13 -2.14 -2.14 -2.15 Aux. for cond. heat rejection -1.86 -2.05 -2.05 -2.05 -2.05 Aux. for heat reject. other than cond. -0.77 -0.82 -0.90 -0.98 Fresh air fan -2.08 -2.05 -2.03 -2.01 Flue gas compressor -25.55 -45.44 -76.60 -100.8 Flue gas expander 11.65 21.25 36.46 48.03 CO2 compression -19.20 -19.02 -18.89 -18.59 Gross Power, MW 419.2 417.1 417.0 417.0 416.9 Net Power, MW 415.6 376.9 366.7 350.8 338.4 Heat input, MW, LHV 711.3 711.3 711.3 711.3 711.3 Net efficiency, %LHV 58.4 53.0 51.6 49.3 47.6 CO2 capture efficiency, % 90.0 90.0 90.0 90.0 Specific emission, kg/MWh 353.7 40.3 41.5 43.3 44.9 CO2 avoided, % 88.6 88.3 87.8 87.3 SPECCA, MJ/kg 2.01 2.63 3.66 4.55 CO2 purity, %mol dry 95.2 96.0 96.5 96.7

5. 5
Economic analysis - Results
Cost of CO2 avoided
020406080100120p_f=1.5barp_f=2barp_f=3barp_f=4barCost of CO2avoided, US$/t Other OpexEnergy OpexCapex - otherCapex - CO2 compr. andtreatm. Capex - flue gas compr./exp. Capex - membranes
73.5 $/t
DOE-NETL MEA baseline: 96 $/t DOE/NETL, 2012. Updated Costs (June 2011 Basis) for Selected Bituminous Baseline Cases.

6. 6
Conclusions

Economic analysis is needed to define the optimal operating parameters of CO2 membrane systems

Optimal operating parameters will depend on the membrane properties (permeability, selectivity) and cost

Techno-economic analysis is a fundamental tool to correctly tailoring the properties of solvent supported membranes to specific applications

Low efficiency penalties (-5.4% pts.) and competitive cost of CO2 avoided (73 $/t) have been obtained for this specific application, with membrane performance and cost in line with state-of-the-art polymeric membranes.

It is likely that existing GT turbines cannot operate with CO2-enrichment as high as obtained with this configuration  The development of tailored GTs is challenging in absence of a sufficient market  limited retrofitability in existing NGCC.

Easier integration and retrofitability in PC plants and other industrial sources (e.g. cement and iron & steel plants) is foreseen for CO2 membranes.

7. 7
MCFC as post-combustion CO2 separation systems

8. 8
MCFC technology can be utilized in cement plant for CO2 separation from fue gases at the preheating tower outlet, and for power production.

Anode side fed with natural gas (direct and indirect internal reforming);

Cathode side fed with fuel gases (@33-34% CO2) and additional air, providing O2.
MCFC in cement plant
CO2 from cement plant
CO2 from NG
CO2 to storage
CO2 to asmosphere
CH4+4CO32-2H2O+5CO2+2e-
2O2+4CO2+8e- 4CO32-
CO32-

9. 9
Q LHV, in [MWLHV]
178.4
MCFC LHV efficiency
52.8
Air utilization factor [UO2,%]
39.3
CO2 Utilization factor [UCO2,%]
70
Fuel cell power [MWE]
106.1
ORC Power [MWE]
8.31
Auxiliares [MWE]
-19.86
Overall net power [MWE]
94.58
Net electric LHV efficiency
53.0
Cement plant flue gas CO2 capture efficiency [%]
73.2
Equivalent CO2 emissions from NG conversion [g/kWh]
-1061
MCFC in cement plant - performance
•
Clinker production = 3600 tpd
•
MCFC voltage = 0.8 V