Application analysis of a hybrid solid oxide fuel cell-gas turbine system for marine power plants

Figures & data

Figure 1. Diagram of a marine electric power plant using SOFC stacks in combination with a regenerative gas turbine operating with over-expansion: 1. electric generator; 2. compressor; 3. turbine; 4. exhauster; 5. gas cooler; 6. regenerator; 7. air superheater; 8. circulation pump; 9. ejector supply of associated gas; 10. preliminary reformer; 11. built-in reformer; 12. combustor; 13 (1), 13 (2). DC-AC inverters; 14. AC-DC inverter; A. atmospheric air; G. exhaust gases; F. fuel supply (associated gas).

Table 1. Results of verification of the gas turbine part’s model.

Microturbine specification parameters	Capstone C30	Capstone C65	Capstone С200S
Electric power, kW	30	65	200
Efficiency, %	26	29	33
Exhaust temperature, K	548	582	553
Calculated parameters	Capstone C30	Capstone C65	Capstone С200S
Electric power, kW / Computational error, %	30.18 / 0.60	66.07 / 1.65	197.69 / −1.15
Efficiency, % / Computational error, %	25.83 / −0.65	28.84 / −0.54	33.28 / 0.85
Exhaust temperature, K / Computational error, %	539.00 / −1.64	585.20 / 0.55	550.00 / −0.54

Table 2. Assumptions for the SOFC stack mathematical model.

Parameters	Value
Total working area (1152 cells), m^2	96.1
Electric stack power, kW	146.5
The efficiency of current transformation by inverters, %	96
Stack efficiency, %	46.24
Fuel consumption (associated gas), g s^−1	7.2
Fuel utilisation factor	0.85
Thermal energy loss in the stack, %	2
Air flow rate at the stack input, kg s^−1	0.303
Total pressure loss in the stack, %	4
Operating stack temperature, K	1183

Figure 2. Efficiency of the SOFC-regenerative gas turbine with overexpansion hybrid scheme.

Figure 3. Gas turbine inlet temperature in a hybrid power generation system.

Figure 4. The total power of a hybrid scheme (kW) per 1 stack.

Table 3. The main parameters of a hybrid SOFC-GT system.

Parameter	Value
Number of Siemens-Westinghouse SOFC stacks	3
Outside temperature, K	288
Air flow through the gas turbine compressor, kg s^−1	0.9084
Compression ratio	1.95
Air temperature at the regenerator inlet, K	363
Internal compressor efficiency, %	81
Air temperature at the regenerator exit, K	800
Air temperature at the superheater exit, K	1053
Air temperature at the stack exit, K	1183
Air pressure at the stack exit, MPa	0.1849
Air flow rate at the stack battery exit, kg s^−1	0.8526
Natural gas total flow rate, kg s^−1	0.0216
Combustible mixture flow rate at the stack battery exit, kg s^−1	0.0786
Combustible mixture temperature at the stack battery exit, K	1183
The gas temperature at the combustion chamber exit, K	1302
Inlet gas turbine temperature, K	1068
Gas flow rate at the turbine inlet, kg s^−1	0.9128
Pressure reduction ratio in gas turbine	2.38
Internal turbine efficiency,%	90
Exit gas turbine temperature, K	878
The gas temperature at the regenerator exit, K	448
Compression ratio in gas turbine exhauster	1.4
Exhauster internal efficiency, %	82
The temperature at the exhauster inlet, K	294
The temperature at the exhauster exit, K	330
GTE power, kW	83.19
Stack battery power, kW	440
Total power, kW	523
Power plant efficiency, %	55

Figure 5. Geometry model of the combustor: (a) longitudinal combustion section; (b) combustion liner.

Table 4. Reactions to the fuel oxidation mechanism.

H + O2$\to$OH + O;	OH + O$\to$H + O2;	O + H2$\to$OH + H;
OH + H$\to$O + H2;	OH + H2$\to$H2O + H;	H2O + H$\to$OH + H2;
OH + OH$\to$H2O + O;	H2O + O$\to$OH + OH;	H + O2+M$\to$HO2+M;
HO2+H$\to$OH + OH;	HO2+H$\to$H2+O2;	HO2+OH$\to$H2O + O2;
CO + OH$\to$CO2+H;	CO2+H$\to$CO + OH;	CH4(+M)$\to$CH3+H(+M);
CH3+H(+M)$\to$CH4(+M);	CH4+H$\to$CH3+H2;	CH3+H2$\to$CH4+H;
CH4+OH$\to$CH3+H2O;	CH3+H2O$\to$CH4+OH;	CH3+O$\to$CH2O + H;
CH2O + H$\to$HCO + H2;	CH2O + OH$\to$HCO + H2O;	HCO + H$\to$CO + H2;
HCO + M$\to$CO + H+M;	CH3+O2$\to$CH3O + O;	CH3O + H$\to$CH2O + H2;
CH3O + M$\to$CH2O + H+M;	HO2+HO2$\to$H2O2+O2;	H2O2+M$\to$OH + OH + M;
OH + OH + M$\to$H2O2+M;	H2O2+OH$\to$H2O + HO2;	H2O + HO2$\to$H2O2+OH;
H + OH + M$\to$H2O + M;		H + H+M$\to$H2+M;

Figure 6. Experimental and calculated dependences of air flow via the ejector on air flow via the combustor: (a) – cool blow mode; (b) – hot blow mode.

Figure 7. Velocity vector coloured by velocity magnitude, m s⁻¹.

Figure 8. Contours of static temperatures, K.

Figure 9. Contours of mass fraction of (a) H₂; (b) CO; (c) CO₂; (d) NO.