A cycle capable of generating both hydrogen and power with “inherent” carbon capture is proposed and evaluated. The cycle uses chemical looping combustion to perform the primary energy release from a hydrocarbon, producing an exhaust of CO. This CO is mixed with steam and converted to H2 and CO2 using the water-gas shift reaction (WGSR). Chemical looping uses two reactions with a recirculating oxygen carrier to oxidize hydrocarbons. The resulting oxidation and reduction stages are preformed in separate reactors—the oxidizer and reducer, respectively, and this partitioning facilitates CO2 capture. In addition, by careful selection of the oxygen carrier, the equilibrium temperature of both redox reactions can be reduced to values below the current industry standard metallurgical limit for gas turbines. This means that the irreversibility associated with the combustion process can be reduced significantly, leading to a system of enhanced overall efficiency. The choice of oxygen carrier also affects the ratio of CO versus CO2 in the reducer’s flue gas, with some metal oxide reduction reactions generating almost pure CO. This last feature is desirable if the maximum H2 production is to be achieved using the WGSR reaction. Process flow diagrams of one possible embodiment using a zinc based oxygen carrier are presented. To generate power, the chemical looping system is operated as part of a gas turbine cycle, combined with a bottoming steam cycle to maximize efficiency. The WGSR supplies heat to the bottoming steam cycle, and also helps to raise the steam necessary to complete the reaction. A mass and energy balance of the chemical looping system, the WGSR reactor, steam bottoming cycle, and balance of plant is presented and discussed. The results of this analysis show that the overall efficiency of the complete cycle is dependent on the operating pressure in the oxidizer, and under optimum conditions exceeds 75%.

1.
Haywood
,
R. W.
, 1991,
Analysis of Engineering Cycles—Power, Refrigeration and Gas Liquefaction Plant
,
4th ed.
,
Pergamon
,
Oxford
, pp.
38
42
.
2.
Haywood
,
R. W.
, 1974, “
A Critical Review of the Theorems of Thermodynamic Availability, With Concise Formulations—Part I: Availability
,”
J. Mech. Eng. Sci.
0022-2542,
16
, pp.
160
173
.
3.
McGlashan
,
N. R.
, 2008, “
Chemical Looping Combustion—A Thermodynamic Study
,”
Proc. Inst. Mech. Eng., Part C: J. Mech. Eng. Sci.
0954-4062,
222
, pp.
1005
1019
.
4.
Horlock
,
J. H.
, 2002,
Combined Power Plants
,
1st ed.
,
Krieger
,
Malabar, FL
, pp.
35
36
.
5.
Richter
,
H. J.
, and
Knoche
,
K. F.
, 1983, “
Reversibility of Combustion Processes
,”
Efficiency and Costing—Second Law Analysis of Processes
(
ACS Symposium
Series No. 235),
American Chemical Society
,
Washington, DC
, pp.
71
85
.
6.
Ishida
,
M.
, and
Jin
,
N.
, 1997,
“CO2 Recovery in a Power Plant With Chemical Looping Combustion
,”
Energy Convers. Manage.
0196-8904,
38
, pp.
S187
S192
.
7.
Brandvoll
,
Ø.
, and
Bolland
,
O.
, 2004, “
Inherent CO2 Capture Using Chemical Looping Combustion in a Natural Gas Fired Cycle
,”
ASME J. Eng. Gas Turbines Power
0742-4795,
126
, pp.
316
321
.
8.
Naqvi
,
R.
, and
Bolland
,
O.
, 2007, “
Multi-Stage Chemical Looping Combustion (CLC) for Combined Cycles With CO2 Capture
,”
Int. J. Greenhouse Gas Control
,
1
, pp.
19
30
.
9.
Mattisson
,
T.
,
García-Labiano
,
F.
,
Kronberger
,
B.
,
Lyngfelt
,
A.
,
Adánez
,
J.
, and
Hofbauer
,
H.
, 2007, “
Chemical-Looping Combustion Using Syngas as Fuel
,”
Int. J. Greenhouse Gas Control
,
1
, pp.
158
169
.
10.
Leion
,
H.
,
Mattisson
,
T.
, and
Lyngfelt
,
A.
, 2008, “
Solid Fuels in Chemical-Looping Combustion
,”
Int. J. Greenhouse Gas Control
,
2
, pp.
180
193
.
11.
Anheden
,
M.
, and
Svedberg
,
G.
, 1998, “
Exergy Analysis of Chemical-Looping-Combustion Systems
,”
Energy Convers. Manage.
0196-8904,
39
, pp.
1967
1980
.
12.
McGlashan
,
N. R.
,
Heyes
,
A. L.
, and
Marquis
,
A. J.
, 2007, “
Carbon Capture and Reduced Irreversibility Combustion Using Chemical Looping
,” ASME Paper No. GT2007-28116.
13.
Hougan
,
O. A.
, and
Watson
,
K. M.
, 1947,
Chemical Process Principles—Part 2 Thermodynamics
,
1st ed.
,
Wiley
,
New York
, pp.
737
741
.
14.
Jerndal
,
E.
,
Mattisson
,
T.
, and
Lyngfelt
,
A.
, 2006, “
Thermal Analysis of Chemical-Looping Combustion
,”
Trans. Inst. Chem. Eng., Part A
0263-8762,
84
, pp.
795
806
.
15.
Winterbone
,
D. E.
, 1997,
Advanced Thermodynamics for Engineers
,
1st ed.
,
Arnold
,
London
, pp.
47
48
.
16.
Berkowitz
,
N.
, 1979,
An Introduction to Coal Technology
,
1st ed.
,
Academic
,
New York
, p.
275
.
17.
Newsome
,
D. S.
, 1980, “
The Water-Gas Shift Reaction
,”
Catal. Rev. - Sci. Eng.
0161-4940,
21
, pp.
275
318
.
18.
Kubaschewski
,
O.
,
Evans
,
E. LL.
, and
Alcock
,
C. B.
, 1967,
Metallurgical Thermochemistry
,
4th ed.
,
Pergamon
,
New York
, pp.
303
447
.
19.
Kelley
,
K. K.
, 1949, “
Critical Evaluation of High-Temperature Heat Capacities of Inorganic Compounds
,” U.S. Bureau of Mines Bulletin No. 476.
20.
Yaws
,
C. L.
, 1999,
Chemical Properties Handbook
,
1st ed.
,
McGraw-Hill
,
New York
, pp.
109
110
.
21.
Moore
,
J. M.
, and
Siverding
,
C. H.
, 1976,
Two-Phase Steam Flow in Turbines and Separators
,
1st ed.
,
Hemisphere
,
Washington, DC
, p.
22
.
22.
Maier
,
C. G.
, 1930, “
Zinc Smelting From a Chemical and Thermodynamic Viewpoint
,” U.S. Bureau of Mines Bulletin No. 324.
23.
Barton
,
P. I.
, and
Pantelides
,
C. C.
, 1994, “
Modelling of Combined Discrete/Continuous Processes
,”
AIChE J.
0001-1541,
40
, pp.
966
979
.
24.
Oh
,
M.
, and
Pantelides
,
C. C.
, 1996, “
A Modelling and Simulation Language for Combined Lumped and Distributed Parameter Systems
,”
Comput. Chem. Eng.
0098-1354,
20
, pp.
611
633
.
25.
Schumann
,
R.
, and
Schadler
,
H. W.
, 1960, “
Chemistry and Physics of Zinc Technology
,”
Zinc—The Science and Technology of the Metal, Its Alloys and Compounds
(
ACS Monograph
No. 142),
C. H.
Mathewson
, ed.,
Reinhold Publishing Corporation
,
New York
, pp.
65
102
.
26.
Azakami
,
T.
, 1985, “
Thermodynamic Studies on Reduction of Zinc Oxide
,”
Zinc ‘85, Proceedings of the International Symposium on Extractive Metallurgy of Zinc
, Tokyo, Japan,
The Mining and Metallurgical Institute of Japan
,
Tokyo, Japan
, pp.
201
216
.
You do not currently have access to this content.