ANALYSIS OF PARAMETERS AFFECTING THE EFFICIENCY OPTIMIZATION OF BINARY SOFC CO-GENERATION POWER PLANTS

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 10, October (2014), pp. 180-190 © IAEME
180
ANALYSIS OF PARAMETERS AFFECTING THE
EFFICIENCY OPTIMIZATION OF BINARY SOFC
CO-GENERATION POWER PLANTS
Done Tashevski1
, Risto Filkoski2
, Dame Dimitrovski3
, Igor Shesho4
Faculty of Mechanical Engineering, University “Ss Cyril and Methodius”,
Karpos II bb, 1000 Skopje, Republic of Macedonia, Email: done.tashevski@mf.edu.mk
ABSTRACT
Binary co-generation power plants with solid oxide fuel cells (BCFC) belong to the category
of modern power systems with high efficiency. Calculation and optimization of this type of power
plants is a complex task, due to a number of influencing variables (parameters). The objective of the
present study is obtaining a realistic insight of the importance of the certain variables (parameters),
narrowing of the value ranges and assessing the overall impact of the considered variables to the
efficiency of the fuel cells and the plant as whole, including electricity and thermal power output.
Particular attention is devoted to the analysis of the impact of the fuel cell parameters to the plant
efficiency. For the analysis of the impact of each parameter, previously developed and verified
mathematical model is used, based on the exergy method. The impact of each parameter to the plant
efficiency is separately analyzed and explained. As a result of the analysis, the optimum range of
values of each variable is determined, at which the maximum efficiency is obtained.
Keywords: Binary Co-Generation Power Plant, Optimization, Solid Oxide Fuel Cell.
1. INTRODUCTION
Binary co-generation power plants with solid oxide fuel cells (BCFC) belong to the category
of modern power systems composed of high-temperature solid oxide fuel cells (SOFC), gas turbine
(GT) and steam turbine (ST) co-generation power plant. These plants are characterized by a threefold
production of electricity (SOFC inverter, gas and steam turbine generators) and reusable production
of thermal energy (co-generation steam turbine) [1,2,3,4].
In this way drafted complex plants are characterized by a number of parameters (variables)
that have different impacts on the BCFC optimization (Fig.1). To be able to make a detailed analysis
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of the impact of each parameter previously is developed and verified mathematical model (software
package) for the calculation and optimization of BCFC. This software package is prepared by the
Institute for Thermal Engineering, Faculty of Mechanical Engineering in Skopje [5,6]. For obtaining
a realistic insight of overall BCFC efficiency, calculation is based on the exergy method [7,8,9].
Figure 1: BCFC parameters subject of analysis
Table 1: Input parameters (input data) of analysed BCFC
BCFC Input parameters
Gas fuel
(natural gas)
Gaseous fuel
(solid and liquid)
SOFC electrical power MW 100 100
Individual SOFC voltage V 0.7 0.7
SOFC fuel utilization % 93 93
SOFC oxidant utilization % 85 18
SOFC fuel inlet temperature K 823 673
SOFC oxidant inlet temperature K 973 973
Fuel composition
CH4/C2H6/C3H8/N2/CO2/CO/H2
%
97/0.2/1.8/1.0/-
/-
0.6/-
/0.6/8.0/45.2/33.9
Oxidant (air) composition
O2/N2/H2O
% 20.8/78.2/1.0 20.8/78.2/1.0
Compressor air inlet temp. o
C 15 15
Compressor pressure ratio - 3 7
HRSG steam outlet press./temp. MPa/ o
C 5 14/560
Steam extraction pressure MPa 0.5 0.5
Specific steam extraction kg/kg 0.3 0.3
Deaerator/Condenser pressure MPa 0.7/0.006 0.7/0.006
For analysis of the impact of parameters on the optimization of BCFC is used BCFC on gas
and gaseous fuel (gasified from solid/liquid fuel) with parameters given in Table 1, where is properly
modified a parameter that is the subject of analysis.

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Analyzing is the impact of parameters on the values (results) of electrical and thermal power,
electrical efficiency and the main emphasis is the analysis of the impact of each parameter on the
optimization criteria, i.e. overall BCFC efficiency [10-15]. When doing the analysis, one variant of
BCFC with large power output is selected, represented with a SOFC of 100 MW, with and without
additional combustion (burner AB) placed ahead of the gas turbine (GT) and heat recovery steam
generator (HRSG).
2. ANALYSIS OF PARAMETERS AFFECTING THE EFFICIENCY
2.1 Impact of the type of gas fuel
Fuels which are reach in methane, such as the natural gas, biogas etc. can be used as base
fuels directly in the SOFC without going through the reforming phase (Table 2). These types of fuels
in the SOFC are inside reformed into gas fuel with high percentage of H2 (chemical equations for
inside gas fuel reforming) [1, 4, 5].
Table 2: Impact of type of gas fuel
Results NG Biogas Lignite Oil
SOFC gas fuel consumpt. kg/s 3.34 8.152 22.87 17.148
SOFC air consumption kg/s 62.03 62.029 163.14 205.630
SOFC outlet gas flow kg/s 65.37 70.184 186.01 222.778
SOFC electrical power kW 100,000.0 100,000.0 100,000.0 126,000.0
SOFC electrical efficiency - 0,689 0,423 0.354 0.431
GT electrical power kW 12,076.66 13,395.45 82,305.27 50,906.82
ST electrical power kW 5,793.73 6,924.77 38,634.16 43,093.64
ST thermal power kW 5,102.72 5,928.64 21,948.26 24,490.28
BCFC electrical power kW 117,870.4 120,320.2 220,939.4 220,000.5
BCFC elect. efficiency - 0.812 0.509 0.642 0.735
BCFC overall efficiency - 0.824 0.517 0.665 0.764
Lignite/oil consumption kg/s - - 20.58 6.86
From the presented data in Table 2 can be drawn conclusion that, using natural gas reach in
methane with inside reforming process within the SOFC, results in gas fuel with improved quality,
higher percentage of H2, higher electrical and overall efficiency of the BCFC compared to that with
biogas [16, 17].
The BCFC parameters are highly influenced by the gas fuel composition obtained by the
gasification process of solid and liquid fuels (lignite, oil etc.). The gasification unit (outsource fuel
reformer) design is depends from the fuel type (solid, liquid). Analysis for the fuel type impact is
done for BCFC with equal electrical power (Table 2), and for known gas fuel composition obtained
in gasifiers which are already in function [17,18]. Table 2 data’s shows that using more quality
gaseous fuels (higher H2 content), results in SOFC with higher electrical efficiency. Using same type
of gasifier (Destec), the oil gasifier gives more quality fuel, compared to that obtained in the lignite
gasifier. In the oil gasifier is required less oil quantity than that on lignite, for obtaining the same gas
fuel quantity [18, 19].
2.2 Impact of gas fuel utilization
Fuel utilization at the individual fuel cells, according the producer recommendation is in the
limits of 75-85 % and for the modular fuel cells (subject of this analysis) is higher and is above 90 %
[20, 21].

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Table 3: Impact of gas fuel utilization
Results Gas fuel utilization
90 % 93 % 95 %
SOFC fuel consumption kg/s 3.45 3.34 3.27
SOFC air flow kg/s 62.03 62.03 62.03
SOFC gases flow kg/s 65.48 65.37 65.29
SOFC gases exit temperature °C 1,113.483 1,041.113 995.152
SOFC electrical power kW 100,000.0 100,000.0 100,000.0
GT electrical power kW 13,414.16 12,076.66 11,242.92
ST steam flow kg/s 8.543 7.35 6.538
ST steam extraction flow kg/s 2.563 2.205 1.961
ST electrical power kW 7,506.626 5,793.739 4,805.025
ST (BCFC) thermal power kW 6,211.477 5,102.727 4,399.967
BCFC electrical power kW 120,920.79 117,870.39 116,047.95
BCFC electrical efficiency - 0.806 0.812 0.817
BCFC overall efficiency - 0.820 0.824 0.827
ST exit steam quality (wetness) % 6.0 9.0 13.0
The results presented in Table 3 shows that at lower value of the fuel utilization in SOFC it is
need more fuel for the same power. During lower utilization of fuel, in flue gases from fuel cell is
increased the percentage content of fuel elements H2 and CO. They additional combust in the
additional combustion chamber, causing an increase in the proportion of the reaction components in
the flue gas CO2 and H2O, as well as higher temperature at the SOFC exit. Due to the higher
temperature of flue gases from SOFC, the gas turbine flue gas temperature increases, which affect
the improvement of the parameters of the cogeneration steam turbine. Increasing the fuel utilization
over 95 % results with deterioration in the quality of the steam (deep wetness) at the exit of steam
turbine, which is unacceptable. This means that these plants can operate with maximum fuel
utilization by 93 %. By reducing fuel utilization decreases SOFC and gas turbine electrical
efficiency. Generally, reducing the fuel utilization reduces electrical and overall efficiency of BCFC,
and inversely proportional increase its electrical power.
2.3 Impact of oxidant utilization
Oxidant (air) utilization of in the individual fuel cells by producers are recommended to move
up to 50 %, and the modular fuel cell on natural gas allows higher oxidant utilization by 80-85 %
[19.20]. From the results shown in Table 4 can be concluded that the oxidant utilization does not
affect directly the performance of SOFC, because they do not affect the fuel consumption. With the
increasing oxidant utilization, increases the temperature of the flue gas outlet from the SOFC (after
additional chamber combustion). It reduces the flow of oxidant and the flue gas, which directly
affects the reduction of gas turbine power and efficiency. The higher flue gas temperature from the
SOFC affects on the increase of the gas turbine flue gas temperature, which positively affects the
steam outlet parameters from the HRSG, reduces thermal power and increases the electrical power
and efficiency of the steam turbine. But with the increasing oxidant utilization it is reduced the total
and electrical power and the overall efficiency of the BCFC. During utilization of the oxidant less
than 80 % at the output of the steam turbine is achieved inadmissible steam quality (deep wetness).
From the above can be concluded that these facilities achieve the highest overall efficiency when the
oxidant utilization is in the range of 80-85 %.

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Table 4: Impact of oxidant utilization
BCFC on natural gas
Results
Oxidant utilization
70 % 80 % 85 % 90%
SOFC fuel consumption kg/s 3.34 3.34 3.34 3.34
SOFC air flow kg/s 75.32 65.91 62.03 58.58
SOFC gases flow kg/s 78.66 69.25 65.37 61.92
SOFC gases exit temp. °C 1,011.37 1,031.40 1,041.11 1,050.64
SOFC efficiency - 0.689 0.689 0.689 0.689
ST steam flow kg/s 7.760 7.475 7.35 7.234
ST steam extraction flow kg/s 2.328 2.243 2.205 2.170
ST (BCFC) thermal power kW 5,227.97 5,140.16 5,102.73 5,068.77
BCFC electrical efficiency - 0.820 0.814 0.812 0.810
ST exit steam quality % 13 11 9 8
BCFC on lignite
Results
Oxidant (air) utilization
10 % 15 % 18 % 20 %
SOFC gas fuel consump. kg/s 22.87 22.87 22.87 22.87
SOFC air flow kg/s 280,30 192,43 163.14 148.49
SOFC exit gases flow kg/s 303.17 215.29 186.01 171.36
SOFC exit gases temp. o
C 1,149.9 1,345.44 1,449.12 1,583.33
SOFC electrical efficiency - 0.354 0.354 0.354 0.354
ST (BCFC) thermal power kW 18,798.35 21,425.46 21,948.26 22,217.13
Lignite consumption kg/s 20.58 20.58 20.58 20.58
ST exit steam quality % 16 10 6 4
From the manufacturer recommendations the oxidant utilization in the fuel cells on solid and
liquid fuels is lower and is in the limits of 10-20 % [20,21]. In Table 6 is presented the impact of
oxidant utilization for BCFC on lignite. Table 4 results shows that the influence of the oxidant
utilization using gaseous fuels and gaseous fuels produced by gasification of solid and liquid fuels is
very similar. During oxidant utilization by 20 % the output of the SOFC achieves temperatures
higher than 1500 °C, which temperatures exceed the maximum allowed inlet gas temperature of gas
turbine. On the other hand, the oxidant utilization of 10 % results with deterioration in the quality of
steam at exit of steam turbine (deep wetness), which is unacceptable. From this can be concluded
that the highest overall efficiency of BCFC on solid fuel is achieved in the range of oxidant
utilization of 15-18 %. Better efficiency is achieved at values close to 18 %.
2.4 Impact of individual fuel cells voltage
Modern individual fuel cells are manufactured with a voltage of 0.5-0.7 V [1,20,21].
According to the present status of the fuel cell this voltage for the individual cells is sufficient to
achieve required performance and the required electrical power to the SOFC. With increasing of fuel
cell voltage reduces SOFC fuel consumption and electricity current. BCFC achieve higher efficiency
(0.824) at higher voltages (0.7 V).

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2.5 Impact of SOFC inlet fuel and oxidant temperature
The influence of the temperature of the fuel and oxidant at the inlet of the SOFC needs to be
considered together because of their mutual connection with performing the chemical reactions and
internal reforming SOFC (fuel heating, BCFC on natural gas). For this purpose the previously
analyzed temperature difference between the temperature of oxidant and the fuel. The temperature of
the gas fuel into the modern SOFC, recommended by the manufacturers for the proper and smooth
execution of the reaction is not allowed to be lower than 500 °C. At lower temperature of the fuel is
achieved SOFC operating temperature of the 800 °C, which is significantly lower than the
recommended 1000 °C, which significantly affects the deterioration of the parameters of the BCFC
[1, 3, 4, 5, 20, 21].
Therefore the change of the temperature difference between the temperature of the fuel and
the oxidant at the inlet of the SOFC, it is necessary to monitor the flue gas temperature of the SOFC
output. The temperature of the gas the outlet of the fuel cell module before additional combustion
chamber should be around 850 °C [1,7].
Table 5: Impact of SOFC fuel and oxidant inlet temperature
Results Temperature difference 150-250 o
C
SOFC fuel inlet temperature o
C 550 550 650
SOFC oxidant inlet temperature o
C 700 750 800
SOFC air flow kg/s 62.03 62.03 62.03
SOFC gases exit temperature °C 1,041.113 1,012.829 1,044.875
SOFC efficiency - 0,689 0,689 0,689
ST electrical power kW 5,793.739 4,362.421
ST (BCFC) thermal power kW 5,102.727 4,070.955
BCFC electrical power kW 117,870.39 115,968.922
BCFC electrical efficiency - 0.812 0.799
BCFC overall efficiency - 0.824 0.808
The temperature difference of the fuel and of the SOFC entry from 0-100 °C, are obtained
unrealistically high temperature for the flue gases at the outlet of the SOFC module before the
additional combustion chamber 900-950 °C. During temperature differences of 150 and 200 °C, are
achieved realistic gas temperatures of about 850 °C.
From Table 5 can be seen that by increasing the temperature difference between the fuel and
the oxidant at the SOFC inlet, the electrical power and overall efficiency of the BCFC are reduced. It
occurs due to a decrease in temperature of the flue gases at the outlet of the module, which directly
affects the temperature decrease at the SOFC outlet after the additional combustion chamber. As a
result of that it is reduced the power and efficiency of the gas turbine. On the other hand, raising the
temperature of the oxidant causes increased need for heating the oxidant in the recuperator, and
deterioration of the characteristics of co-generation steam turbine. That can be seen in the last case
shown in Table 5, when there is no possible combination with steam turbine. Increasing in the fuel
temperature at the fuel inlet in the SOFC increases the required heat for its heating and reforming.
That again causes decrease in the power, electrical and overall efficiency of the BCFC. So far the
highest values of power, electrical and overall efficiency are achieved for fuel temperature at the
entrance of 500-550 °C and temperature of the oxidant at the fuel cell entry of 700-750 °C.
The BCFC of solid and liquid fuel the fuel temperature at the fuel cell inlet can be lower and
ranges from 400-450 °C, and the influence on power and overall performance is identical.

186
2.6 Impact of SOFC pressure
SOFC operates with pressures up to 15 bar. According to recent research (Siemens-
Westinghouse) these SOFC-s can operate with pressures up to 30 bar [20,21].
From the results in Table 6 it can be concluded that an increase in pressure (compressor
pressure ratio) increases the gas turbine electrical power and electrical efficiency. But on the other
hand, it is reduced the temperature of the flue gases of gas turbine, which causes a decrease outlet
steam temperature of the HRSG, where exists the possibility of deterioration in the quality of the
steam at the steam turbine, as it is for the pressures ratio 4.0. For the compressor pressures ratio of
3.0 it is achieved greater gas turbine power, but because of the lower flue gas temperature at the
outlet of the gas turbine, steam turbine characteristics are less favorable in relation of those in
pressures ratio of 2.0. This means that with the increase in the pressures ratio the gas turbine
characteristics are improved, and deteriorated the steam turbine characteristics. In general an
increase in the compressor pressures ratio increases electrical power, electrical and overall efficiency
of the BCFC. From the above analysis can be concluded that BCFC without additional combustion
can work in maximum pressures ratios of 3.0.
The pressure ratios in the compressor has pronounced influence in the BCFC with additional
combustion before the gas turbine and HRSG (steam pressure and temperature of 14 MPa and 560
°C). From the obtained results presented in Table 6 can be concluded that BCFC with additional
combustion achieves the highest efficiency and electrical power, for pressure ratios between 8.0-
10.0 [22]. Maximum overall efficiency are achieved at BCFC without additional combustion. Higher
electrical power is achieved at BCFC with additional combustion.
Table 6: Impact of SOFC pressure
BCFC without additional combustion
Results
Compressor pressure ratio
2 3 4
SOFC gases exit temperature °C 1,041.113 1,041.113 1,041.113
SOFC efficiency - 0.689 0.689 0.689
BCFC electrical power kW 114,714.33 117.870.39 119,678.16
ST exit steam quality/wetness % 6 9 13
BCFC with additional combustion
Results
Compressor pressure ratio
6 8 10 12 14
SOFC fuel consum. kg/s 3.34 3.34 3.34 3.34 3.34
SOFC gases flow kg/s 65.37 65.37 65..37 65.37 65.37
SOFC elec. power kW 100,000 100,000 100,000 100,000 100,000
SOFC elec. effic. - 0.689 0.689 0.689 0.689 0.689
AB1 fuel consump. kg/s 1.08 1.08 1.08 1.08 1.08
GT gases flow kg/s 66.45 66.45 66.45 66.45 66.5
AB2 fuel consump. kg/s - - 0.033 0.064 0.085
HSRG gases flow kg/s 66.45 66.45 66.482 66.513 66.534
GT electric. power kW 30,560.1 33,521.9 35,342.1 36,525.3 37,314.9
ST electrical power kW 14,540.1 14,489.8 14,461.0 14,440.1 14,422.1
ST thermal power kW 8,370.41 8,341.5 8,324.9 8,312.8 8,302.5
Total fuel consum. kg/s 4.42 4.42 4.45 4.48 4.50
BCFC elec. power kW 145,100 148,011 148,515 148,030 147,142
BCFC elec. effic. - 0.755 0.770 0.767 0.760 0.752
BCFC overall effic. - 0.771 0.785 0.782 0.775 0.766

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2.7 Impact of SOFC fuel inlet pressure
The pressure of the fuel at the SOFC inlet is required to be approximately 50 % higher than
the operating pressure in the cell (the manufacturer’s recommendations) [20,21]. Fuel pressure
depends from the pressure of the natural gas in the distribution network. If the pressure in the
network is lower than necessary, further compressing the fuel is needed, which directly affects the
reduction of total power BCFC (reduced power to drive the compressor). In Macedonia joining on
the secondary pipeline (12 bar) of the network [16,17]. In that case, the BCFC without additional
combustion has no need for compressor, but with reduction on the pressure in the network will be
reached the SOFC fuel pressure, and at the BCFC with additional combustion there is need for a fuel
compressor which directly affects the reduction on the electrical power and overall efficiency on the
BCFC (Table 7).
Table 7: Impact of SOFC fuel inlet pressure
Results
Compressor pressure ratio (gas turbine)
10 12
Additional combustion with without with without
NG net pressure MPa 1.2 1.2 1.2 1.2
Fuel pressure MPa 1.426 - 1.71 -
Fuel compressor power kW 1,288.34 - 2,935.23 -
BCFC electrical efficien. - 0.767 0.774 0.760 0.775
2.8 Impact of gas turbine inlet temperature
The temperature at the inlet in the gas turbine at BCFC without additional combustion
depends from the temperature on the flue gases from the SOFC, which in the analysis is repeatedly
emphasized. Inlet temperature in the gas turbine at BCFC with burner for additional combustion
before the gas turbine, provides the possibility for the modern gas turbines to reach the maximum
recommended 1500 °C (Mitsubishi – Japan) [22]. It directly affects the increase on the gas turbine
electric power and thus on the electrical power and overall efficiency of the BCFC.
2.9 Impact of HRSG steam pressure and temperature
From the results (Table 8) can be concluded that the BCFC without additional combustion
with increasing the steam pressure at the HRSG increases the electrical power of the steam turbine,
causing an increase in total electric power on the BCFC. On the other hand for the low value is
reduced the heating power as a result on the lower value of the inlet enthalpy in the steam consumer.
With the increase of the steam pressure at the HRSG it increases the electrical power, and thus the
overall efficiency of the BCFC. With further increase of the steam vapor pressure at the HRSG to 6
MPa, the output of the steam turbine achieves deep wetness. For this reason these BCFC operate
with vapor pressure at the HRSG with up to 5 MPa. The BCFC with burner for additional
combustion installed before HRSG does not exists a possibility of deep wetness at the outlet of the
steam turbine. This means that can be used HRSG which operate at high steam pressures up to 14
MPa.
The steam temperature at the outlet of the HRSG at BCFC without additional combustion
depends on the flue gases temperature after air recuperator. Its influence is mentioned several times
during the analysis. At the BCFC with burner for additional combustion (AB) before the HRSG, the
temperature of the steam at the outlet of the HRSG depends from the characteristics of the selected
HRSG. From Table 8 can be concluded that an increase in temperature at the outlet of HSRG
increases the electrical and thermal power of the steam turbine and thus the total electrical power of
the BCFC. Due to achieving higher temperature at the outlet of the HRSG increases the fuel

188
consumption of the burner for additional combustion (AB2), which causes an increase in total fuel
consumption at the BCFC. It directly affects on the reduction of the electrical power and the overall
efficiency of the BCFC (steam temperature of 600 °C). This means that these power plants operates
optimal between the steam temperatures of 500-600 °C at the outlet of the HRSG, and the highest
values of electrical and overall efficiency are achieved at standard steam temperature of 560 °C.
Table 8: Impact of HRSG steam pressure and temperature
Results
HRSG steam pressure
4 MPa 5 MPa 6 MPa
ST outlet steam quality % 7 9 13
Results
HRSG steam temperature
500 o
C 560 o
C 600 o
C
AB1 fuel consumption kg/s 1.08 1.08 1.08
AB2 fuel consumption kg/s - 0.012 0.094
BCFC total fuel consumption kg/s 4.42 4.43 4.51
Table 9: Impact of extracting steam pressure and specific flow for heat consumer
Pressure of steam extraction (0.3 MPa)
Results
Specific flow of steam extraction kg/kg
0 0.3 0.5 1.0
ST (BCFC) thermal power kW - 5,090.55 8,775.96 19,202.48
Pressure of steam extraction (1.0 MPa)
Results
Specific flow of steam extraction kg/kg
0 0.3 0.5 1.0
ST (BCFC) thermal power kW - 5,127.05 8,785.15 19,897.61

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2.10 Impact of steam turbine extracted steam pressure, flow and temperature
The pressure of the regulated steam extraction for the technological needs vary depending on
the type technological consumer [23].
From the results presented in Table 9 can be concluded that by increasing the flow of
extracted steam, it increases the thermal power of the power plant as a result of the electrical power it
is reduced the electrical efficiency and increased the overall efficiency. With the increasing of the
pressure of steam extraction increases the thermal power plant, but overall performance is lower for
low-value, as a result of the reduction of the electric power of the power plant at higher pressures of
steam extraction.
From what has been said can be concluded that to achieve higher overall efficiency, it takes
lower pressure and higher specific flow of steam extraction for the technological consumer. The
highest values of the electrical efficiency is achieved when the plant operates with condensing
turbine and on the overall efficiency when operates with back-pressure turbine.
3. CONCLUSION
This analysis contributes to the narrowing parameters (variables) field of vary affecting the
efficiency optimization of BCFC and it can be concluded that the highest overall efficiency (criteria
of optimization) is achieved when:
- Utilizing quality gas fuels with high percentage of H2,
- Fuel utilization of 90-93 %
- Oxidant utilization for BCFC on gas fuels (natural gas) from 80-85 % and for BCFC on
gasified fuels 15-18 %
- Voltage on the individual cell from 0.7 V,
- Fuel temperature 500-550 °C (BCFC on gas fuels) and 450-500 °C (BCFC on gasified fuels)
and the oxidant temperature 700-750 °C,
- The pressure in SOFC i.e. the compressor pressure ratio for BCFC without additional
combustion up to 3 and BCFC with additional combustion 8-10,
- Steam pressure in HRSG up to 5 MPa (BCFC without additional combustion) and up to 14
MPa (BCFC with additional combustion)
- Steam temperature at outlet of HRSG from 500-600 °C (BCFC with additional combustion
and appropriate HRSG selection (BCFC without additional combustion).
- Without gas fuel compressor (BCFC without additional combustion),
- Lower pressures and higher specific flow of steam extraction for the technological consumer.
- Integrating of backpressure turbines.
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