Power generation with an externally red gas turbine (EFGT) is a promising technology for solid fuels such as coal and biomass because it offers high ef ciency, low cost, and low environmental impacts. Different systems of EFGT are presented, including externally red combined cycles and externally red humid air turbines. Recent research and engineering development of the technologies are reviewed. Topics including system con gurations, thermal ef ciencies, and high-temperature heat exchangers issues are discussed. The results of this study can be applied to guide the future development of solid-fuel-based externally red gas turbine systems.
This paper is a presentation of systematic study on externally fired gas turbine cogeneration fueled by biomass. The gas turbine is coupled in series with a biomass combustion furnace in which the gas turbine exhaust is used to support combustion. Three cogeneration systems have been simulated. They are systems without a gas turbine, with a non top-fired gas turbine, and a top-fired gas turbine. For all systems, three types of combustion equipment have been selected: circulating fluidized bed (CFB) boiler, grate fired steam boiler and grate fired hot water boiler. The sizes of biomass furnaces have been chosen 20 MW and 100 MW fuel inputs. The total efficiencies based on electricity plus process heat, electrical efficiencies, and the power-to-heat ratios for various alternatives have been calculated. For each of the cogeneration systems, part load performance with varying biomass fuel input is presented. Systems with CFB boilers have a higher total efficiency and electrical efficiency than other systems when a top-fired gas turbine is added. However, the systems with grate fired steam boilers allow higher combustion temperature in the furnace than CFB boilers do. Therefore, a top combustor may not be needed when high temperature is already available. Only one low grade fuel system is then needed and the gas turbine can operate with very clean working medium.
The pulp and paper industry handles large amounts of energy and today produces the steam needed for the process and some of the required electricity. Several studies have shown that black liquor gasification and combined cycles increase the power production significantly compared to the traditional processes used today. It is of interest to investigate the performance when advanced gas turbines are integrated with next-generation pulp and paper mills. The present study focused on comparing the combined cycle with the integration of advanced gas turbines such as steam injected gas turbine (STIG) and evaporative gas turbine (EvGT) in pulp and paper mills. Two categories of simulations have been performed: (1) comparison of gasification of both black liquor and biomass connected to either a combined cycle or steam injected gas turbine with a heat recovery steam generator; (2) externally fired gas turbine in combination with the traditional recovery boiler. The energy demand of the pulp and paper mills is satisfied in all cases and the possibility to deliver a power surplus for external use is verified. The study investigates new system combinations of applications for advanced gas turbines. Transactions of the ASME Downloaded From: http://gasturbinespower.asmedigitalcollection.asme.org/ on 06/20/2015 Terms of Use: http://asme.org/terms Journal of Engineering for Gas Turbines and Power OCTOBER 2001, Vol. 123 Õ 735 Downloaded From: http://gasturbinespower.asmedigitalcollection.asme.org/ on 06/20/2015 Terms of Use: http://asme.org/terms
This paper is a presentation of a systematic study on externally fired gas turbine cogeneration fueled by biomass. The gas turbine is coupled in series with a biomass combustion furnace in which the gas turbine exhaust is used to support combustion. Three cogeneration systems have been simulated. They are systems without a gas turbine, with a non-top-fired gas turbine, and a top-fired gas turbine. For all systems, three types of combustion equipment have been selected: circulating fluidized bed (CFB) boiler, grate fired steam boiler, and grate fired hot water boiler. The sizes of biomass furnaces have been chosen as 20 MW and 100 MW fuel inputs. The total efficiencies based on electricity plus process heat, electrical efficiencies, and the power-to-heat ratios for various alternatives have been calculated. For each of the cogeneration systems, part-load performance with varying biomass fuel input is presented. Systems with CFB boilers have a higher total efficiency and electrical efficiency than other systems when a top-fired gas turbine is added. However, the systems with grate fired steam boilers allow higher combustion temperature in the furnace than CFB boilers do. Therefore, a top combustor may not be needed when high temperature is already available. Only one low-grade fuel system is then needed and the gas turbine can operate with a very clean working medium.
Externally fired gas turbines have the features of using solid fuel and requiring no particulate cleaning up to protect the gas turbine path. The solid fuel can be, for example, coal or biomass. Evaporative gas turbines (e.g., HAT cycle) have the potential to enhance the power output and increase the efficiency without including a bottoming steam turbine. The integration of the two systems, so called externally fired evaporative gas turbine, can offer the features from both of the systems. In the present paper, the modified externally fired evaporative cycle with intercooling and recuperation is proposed and analyzed. The externally fired gas turbine system is divided into three main subsystems: gas turbine subsystem, solid fuel combustion subsystem and heat recovery subsystem. This paper presents an in-depth investigation of the heat recovery subsystem and its impacts on the total system. The effects of intercooler and aftercooler on the whole system have been addressed and discussed. The optimization strategies for multiple interaction variables, such as air temperature after the recuperation, water-to-air ratio and combustion air temperature for the externally fired combustor, have been provided. The optimization results show that the behavior of the heat recovery subsystem greatly affects the cycle efficiency and power output. Using exhaust heat to heat humid air in a recuperator and to preheat combustion air to the biomass combustor are important for improving the externally fired evaporative gas turbine system. With the electrical efficiency as the objective function of the optimization, there exists an optimum water-to-air ratio located at 0.17 to 0.20 for the system studied in this paper.
The pulp and paper industry handles large amounts of energy and today produces the steam needed for the process and some of the required electricity. Several studies have shown that black liquor gasification and combined cycles increase the power production significantly compared to the traditional processes used today. It is of interest to investigate the performance when advanced gas turbines are integrated with next-generation pulp and paper mills. The present study focused on comparing the combined cycle with the integration of advanced gas turbines such as steam injected gas turbine (STIG) and evaporative gas turbine (EvGT) in pulp and paper mills. Two categories of simulations have been performed: (1) comparison of gasification of both black liquor and biomass connected to either a combined cycle or steam injected gas turbine with a heat recovery steam generator; (2) externally fired gas turbine in combination with the traditional recovery boiler. The energy demand of the pulp and paper mills is satisfied in all cases and the possibility to deliver a power surplus for external use is verified. The study investigates new system combinations of applications for advanced gas turbines.
The integration of externally fired gas turbines and evaporative gas turbines (e.g., the HAT cycle) can offer the features from both systems: using solid fuel without requiring particulate clean up to protect the gas turbine path, and having the potential to enhance the power output and increase the efficiency without including a bottoming steam turbine. Exhaust gases from externally fired evaporative gas turbines have a high moisture content. Using a condensing heat exchanger makes it possible to recover more exhaust heat, thereby providing more potential for improving the system performance. This paper presents a new system with integration of a condensing heat exchanger in an externally fired evaporative gas turbine. The first and second laws of thermodynamics have been used to analyze the system. This study extends the overall knowledge on the externally fired evaporative gas turbine system and provides an investigation of the system with a condensing heat exchanger.
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