scholarly journals Parametric Study of Fuel Cell and Gas Turbine Combined Cycle Performance

1997 ◽  
Author(s):  
Dawn Stephenson ◽  
Ian Ritchey
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Solid Oxide ◽  
Simple Cycle ◽  
Cycle Performance ◽  
Oxide Fuel ◽  
Combined Cycles

A number of cycles have been proposed in which a solid oxide fuel cell is used as the topping cycle to a gas turbine, including those recently described by Beve et al. (1996). Such proposals frequently focus on the combination of particular gas turbines with particular fuel cells. In this paper, the development of more general models for a number of alternative cycles is described. These models incorporate variations of component performance with key cycle parameters such as gas turbine pressure ratio, fuel cell operating temperature and air flow. Parametric studies are conducted using these models to produce performance maps, giving overall cycle performance in terms of both gas turbine and fuel cell design point operating conditions. The location of potential gas turbine and fuel cell combinations on these maps is then used to identify which of these combinations are most likely to be appropriate for optimum efficiency and power output. It is well known, for example, that the design point of a gas turbine optimised for simple cycle performance is not generally optimal for combined cycle gas turbine performance. The same phenomenon may be observed in combined fuel cell and gas turbine cycles, where both the fuel cell and the gas turbine are likely to differ from those which would be selected for peak simple cycle efficiency. The implications of this for practical fuel cell and gas turbine combined cycles and for development targets for solid oxide fuel cells are discussed. Finally, a brief comparison of the economics of simple cycle fuel cells, simple cycle gas turbines and fuel cell and gas turbine combined cycles is presented, illustrating the benefits which could result.

Comparison of a Multi-Megawatt High Temperature Fuel Cell System With Reciprocating Engines and Aero-Derivative Gas Turbines

2008 ◽  
Author(s):  
Georgia C. Karvountzi ◽  
Paul F. Duby
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Gas Turbines ◽  
Cell System ◽  
Combined Cycle ◽  
Simple Cycle ◽  
Fuel Cell System

High temperature fuel cells can be successfully integrated in a simple cycle or in a combined cycle configuration and achieve lower heating value (LHV) efficiencies greater than gas turbines and reciprocating engines. A simple cycle fuel cell system reaches 50 to 51% LHV efficiencies. A fuel cell system integrated with gas and steam turbines in a hybrid system could lead to LHV efficiencies of 70% to 72%. An aero-derivative gas turbine that is the most efficient simple cycle gas turbine achieves 40% to 46% thermal efficiency and a new generation reciprocating engine 39% to 42%. Upon integration in a combined cycle configuration with steam injection, aero-derivative gas turbines potentially reach LHV efficiencies of 55% to 58%. The purpose of the present paper is to compare initially the performance of a stand alone fuel cell with a stand alone gas turbine and a stand alone reciprocating engine. Then the fuel cell is integrated in a hybrid system and it is compared with a gas turbine combined cycle plant. The system sizes explored are 5MW in the stand alone case, and 20MW, 30MW, 60MW, 100MW and 200MW in the hybrid / combined cycle case. The performance of the hybrid system was reviewed under different ambient temperatures (0° F–90° F) and site elevations (0 ft–3000 ft). High temperature fuel cells are more efficient and have lower emissions than gas turbines and reciprocating engines. However fuel cells cannot be used for peak power generation due to long start-up time or load following applications.

Comparison of Molten Carbonate and Solid Oxide Fuel Cells for Integration in a Hybrid System for Cogeneration or Tri-Generation

2004 ◽  
Author(s):  
Georgia C. Karvountzi ◽  
Clifford M. Price ◽  
Paul F. Duby
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Molten Carbonate ◽  
Hybrid Cycle

High temperature fuel cells, such as molten carbonate fuel cells (MCFC) and solid oxide fuel cells (SOFC) can be integrated in a hybrid cycle with a gas turbine and a steam turbine and achieve overall lower heating value (LHV) efficiencies of about 70%. A hybrid cycle designed for cogeneration or tri-generation applications could lead to even higher overall LHV efficiencies. Tri-generation is the combined generation of power, heat and cooling from the same fuel source. The purpose of the present paper is to compare the performance of a 20MW MCFC system and a 20MW tubular SOFC system and assess their potential to cogeneration and tri-generation applications. The system includes a fuel cell, a gas turbine, a multiple pressure heat recovery steam generator (HRSG), a steam turbine and an absorption chiller (for cooling). The systems were designed and sized using GatecycleTM heat balance software by GE Enter Software, LLC. In order to optimize each system we developed curves showing LHV “electric” and “cogeneration” efficiency versus power for different ratios of “MCFC and SOFC fuel cell-to-gas turbines size.” At atmospheric pressure and at 675°C (1247°F) the 20MW MCFC system achieves “electric” efficiency of 69.5%. The SOFC at the same pressure and at 980°C achieves 67.3% “electric” efficiency. The MCFC alone is more efficient (58%) than the SOFC alone (56%). However the SOFC produces more heat than the MCFC leading to slightly higher cogeneration and tri-generation efficiencies. Pressurized operation at 9atm boosts the performance of the SOFC system to higher efficiencies (70.5%). Pressurized operation is problematic for the MCFC due to increased cathode corrosion leading to cathode dissolution as well as sealant and interconnection problems. However we can pressurize the MCFC system independently of the fuel cell with the integration of a gas turbine with a compressor pressure ratio of 10 to 16. Thus we achieve efficiencies close to 69%. In conclusion SOFC is more efficiently integrated in a hybrid configuration with gas turbine and a steam turbine for trigeneration applications when pressurized. MCFC is more efficiently integrated at atmospheric and pressures below 6 atm.

Effect of Fuel Cell Operation Pressure on the Optimization of a Hybrid System SOFC/Turbine for Cogeneration

2004 ◽  
Author(s):  
Georgia C. Karvountzi ◽  
Clifford M. Price ◽  
Paul F. Duby
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Hybrid System ◽  
Heat Balance ◽  
Gas Turbines ◽  
Solid Oxide ◽  
Oxide Fuel

A solid oxide fuel cell (SOFC) integrated in a hybrid system with a gas turbine can achieve lower heating value (LHV) power of efficiencies of about 70%. Given the high operating temperature of the SOFC, it produces high grade heat, and a hybrid system designed for cogeneration may achieve total LHV efficiencies of 78% of 80% without post combustion and 85%–88% with post combustion. The present paper illustrates the optimum integration of a tubular solid oxide fuel cell in a cogeneration cycle with a multiple pressure heat recovery steam generator (HRSG) and a back pressure steam turbine. We considered fuel cells of 7.5 MW, 9 MW, 15 MW, 15 MW, 18 MW, 22.5 MW and 27 MW by scaling up published data for a 1.2 MW tubular solid oxide fuel cell. The operating pressures were 3 and 9atm. We used GateCycle™ heat balance software by GE Enter Software, LLC, to design a 20–40 MW high efficiency cogeneration plant. We performed a calculation of the heat balance of the fuel cell stack in Microsoft® Excel and then we imported the results into GateCycle™. We developed curves showing LHV “electric” efficiency versus power for different ratios of “fuel cell-to-gas turbine size”. Pressurization has a positive impact on the fuel cell polarization curve leading to higher power output. The gain in electric power, however, is offset by the additional power requirement of the compressor at higher pressures. Our analysis shows that an optimum pressure of about 9 atmospheres results in an overall hybrid system power efficiency of about 70% and a LHV “cogeneration” efficiency of about 80%. In conclusion, high efficiencies are obtained by optimization of a hybrid system consisting of pressurized high temperature fuel cells with gas turbines and a steam turbine.

Exergy Analysis of a Solid-Oxide Fuel Cell, Gas Turbine, Steam Turbine Triple-Cycle Power Plant

2012 ◽  
Author(s):  
Rebecca Z. Pass ◽  
Chris F. Edwards
Keyword(s):  
Fuel Cell ◽  
Power Systems ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Exergy Analysis ◽  
Combined Cycle ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Starting Point ◽  
Natural Gas Combined Cycle

In an effort to make higher efficiency power systems, several joint fuel cell / combustion-based cycles have been proposed and modeled. Mitsubishi Heavy Industries has recently built such a system with a solid-oxide fuel cell gas turbine plant, and is now working on a variant that includes a bottoming steam cycle. They report their double and triple cycles have LHV efficiencies greater than 52% and 70%, respectively. In order to provide insight into the thermodynamics behind such efficiencies, this study attempts to reverse engineer the Mitsubishi Heavy Industries system from publicly available data. The information learned provides the starting point for a computer model of the triple cycle. An exergy analysis is used to compare the triple cycle to its constituent sub-cycles, in particular the natural gas combined cycle. This analysis provides insights into the benefits of integrating the fuel cell and gas turbine architectures in a manner that improves the overall system performance to previously unseen efficiencies.

scholarly journals Solid Oxide Fuel Cell Combined Cycles

1996 ◽  
Author(s):  
Frank P. Bevc ◽  
Wayne L. Lundberg ◽  
Dennis M. Bachovchin
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Power Plants ◽  
Combined Cycle ◽  
Solid Oxide ◽  
Plant Performance ◽  
Gaseous Emissions ◽  
Oxide Fuel ◽  
Plant Design ◽  
Combined Cycles

The integration of the solid oxide fuel cell (SOFC) and combustion turbine technologies can result in combined-cycle power plants, fueled with natural gas. that have high efficiencies and clean gaseous emissions. Results of a study are presented in which conceptual designs were developed for three power plants based upon such an integration, and ranging in rating from 3 to 10 MW net ac. The plant cycles are described, and characteristics of key components are summarized. In addition, plant design-point efficiency estimates are presented, as well as values of other plant performance parameters.

Internal Reforming Solid Oxide Fuel Cell Gas Turbine Combined Cycles (IRSOFC-GT): Part B — Exergy and Thermoeconomic Analyses

2001 ◽  
Author(s):  
Aristide F. Massardo ◽  
Loredana Magistri
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Specific Work ◽  
Oxide Fuel ◽  
Internal Reforming ◽  
System Pressure ◽  
Combined Cycles

The aim of this work is to investigate the performance of Internal Reforming Solid Oxide Fuel Cell (IRSOFC) and Gas Turbine (GT) combined cycles. A mathematical model of the IRSOFC steady-state operation was presented in Part A of this work (Massardo and Lubelli, 1998), coupled to the thermodynamic analysis of a number of proposed IRSOFC-GT combined cycles, taking into account the influence of several technological constraints. In the second part of this work, both an exergy and a thermoeconomic analysis of the proposed cycles have been carried out using the TEMP code developed by the Author (Agazzani and Massardo, 1997). A suitable equation for IRSOFC cost evaluation based on cell geometry and performance has been proposed and employed to evaluate the electricity generation cost of the proposed combined systems. The results are presented and the influence of several parameters is discussed: external reformer operating conditions, fuel to air ratio, cell current density, compressor pressure ratio, etc. Diagrams proposed by the Author (Massardo and Scialo’, 2000) for cost vs. efficiency, cost vs. specific work, and cost vs. system pressure are also presented and discussed.

Internal Reforming Solid Oxide Fuel Cell Gas Turbine Combined Cycles (IRSOFC-GT)—Part II: Exergy and Thermoeconomic Analyses

2002 ◽  
Vol 125 (1) ◽  
pp. 67-74 ◽  
Author(s):  
A. F. Massardo
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Specific Work ◽  
Oxide Fuel ◽  
Internal Reforming ◽  
System Pressure ◽  
Combined Cycles

The aim of this work is to investigate the performance of internal reforming solid oxide fuel cell (IRSOFC) and gas turbine (GT) combined cycles. A mathematical model of the IRSOFC steady-state operation was presented in Part I of this work coupled to the thermodynamic analysis of a number of proposed IRSOFC-GT combined cycles, taking into account the influence of several technological constraints. In the second part of this work, both an exergy and a thermoeconomic analysis of the proposed cycles have been carried out using the TEMP code developed by the author. A suitable equation for IRSOFC cost evaluation based on cell geometry and performance has been proposed and employed to evaluate the electricity generation cost of the proposed combined systems. The results are presented and the influence of several parameters is discussed: external reformer operating conditions, fuel-to-air ratio, cell current density, compressor pressure ratio, etc. Diagrams proposed by the author for cost versus efficiency, cost versus specific work, and cost versus system pressure are also presented and discussed.

Performance Evaluation of Solid Oxide Fuel Cell Engines Integrated With Single/Dual-Spool Turbochargers

2011 ◽  
Vol 8 (6) ◽  
Author(s):  
So-Ryeok Oh ◽  
Jing Sun ◽  
Herb Dobbs ◽  
Joel King
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Control Strategies ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Operating Characteristics ◽  
Load Following ◽  
Fuel Flow

This study investigates the performance and operating characteristics of 5kW-class solid oxide fuel cell and gas turbine (SOFC/GT) hybrid systems for two different configurations, namely single- and dual- spool gas turbines. Both single and dual spool turbo-chargers are widely used in the gas turbine industry. Even though their operation is based on the same physical principles, their performance characteristics and operation parameters vary considerably due to different designs. The implications of the differences on the performance of the hybrid SOFC/GT have not been discussed in literature, and will be the topic of this paper. Operating envelops of single and dual shaft systems are identified and compared. Performance in terms of system efficiency and load following is analyzed. Sensitivities of key variables such as power, SOFC temperature, and GT shaft speed to the control inputs (namely, fuel flow, SOFC current, generator load) are characterized, all in an attempt to gain insights on the design implication for the single and dual shaft SOFC/GT systems. Dynamic analysis are also performed for part load operation and load transitions, which shed lights for the development of safe and optimal control strategies.

Combined Heat and Power Systems Based on an Externally Integrated Solid Oxide Fuel Cell – Gas Turbine Hybrid System: The Case of a Hospital Under French Legislation

2004 ◽  
Author(s):  
M. Diacakis ◽  
R. Hales ◽  
M. Morin ◽  
P. Pilidis
Keyword(s):  
Fuel Cells ◽  
Power Systems ◽  
Gas Turbines ◽  
Heat Engine ◽  
Solid Oxide ◽  
Cycle Performance ◽  
Oxide Fuel ◽  
Optimum Configuration ◽  
Maintenance Requirements ◽  
Engine Systems

High temperature Fuel Cells are an attractive technology to generate electricity at high efficiencies. Advantages over traditional heat engine systems include lower irreversibilities, stack modularity and lower maintenance requirements. Solid Oxide Fuel Cells can be coupled with Gas Turbines to further increase cycle performance. In the present study the evaluation of an Externally Integrated Solid Oxide Fuel CellGas Turbine (EISOFCGT) system is presented. The cycle has been designed to meet the requirements of a hospital with a peak thermal demand of 12 MW and electrical of 4.75 MW. Various configurations have been analyzed, with particular emphasis on the effects of operating temperature and air flow-rate in order to identify the optimum configuration. Finally a comparison has been made to a simple CHP plant in order to evaluate the system economics, taking into account the French legislation.

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