Environmental pressures and economic requirements have led to a drive to ever increasing steam parameters to further increase steam turbine cycle efficiencies. This poses a number of challenges: plant architecture,ste...Environmental pressures and economic requirements have led to a drive to ever increasing steam parameters to further increase steam turbine cycle efficiencies. This poses a number of challenges: plant architecture,steam turbine design and turbine material requirements. GE has been developing USC technology for more than 18 years and has many reference plants. The limits on inlet pressure and temperatures have been challenged as the technology and product development has proceeded. This paper discusses some of the options on how plant efficiency can be increased and some of the related challenges. The performance difference between a single reheat and double reheat is quantified based on a simplified thermodynamic model.展开更多
In order to clarify the reason why the creep rupture time of pre-strained Ni-23Cr-7W Alloy (HR6W) is longer than that of the non-pre-strained HR6W, microstructures of HR6W after a series of creep tests were investigat...In order to clarify the reason why the creep rupture time of pre-strained Ni-23Cr-7W Alloy (HR6W) is longer than that of the non-pre-strained HR6W, microstructures of HR6W after a series of creep tests were investigated. The creep tests were conducted at 750°C, 90 and 100 MPa. In the pre-strained samples, the grain boundary shielding ratio by precipitates was larger than that of the non-pre-strained sample. In addition, in the pre-strained samples the size of the M23C6 carbide in the grains was finer than in the non-pre-strained sample. The W content in the M23C6 carbide in the pre-strained samples tended to be larger than in the non-pre-strained sample. Therefore, the Ostwald ripening of the carbide was delayed and the size of M23C6 carbide was thought to be fine for a long time. These observations show that creep strength in the pre-strained samples is higher than that of the non-pre-strained sample because of both precipitation strengthening inside of the grains and grain boundaries.展开更多
The coal-fired power unit integration with a CO2 capture and compression installation involves a considerable rise in the costs of electricity generation. Therefore, there is a need for a continuous search for methods...The coal-fired power unit integration with a CO2 capture and compression installation involves a considerable rise in the costs of electricity generation. Therefore, there is a need for a continuous search for methods of improving the electricity generation efficiency in steam power plants. One technology which is especially promising is the advanced ultra-supercritical (A-USC) power unit. Apart from steam parameters upstream the turbine, the overall efficiency also depends on the efficiency values of individual elements of the plant and the size of energy consumption of the process of CO2 sequestration from the boiler flue gases. These problems are considered herein to emphasize that without specifying the efficiency values of the power plant main elements the information concerning its electricity generation efficiency is incomplete. This paper presents the influence of the efficiency of individual elements of the power plant on its electricity generation efficiency. The lack of information of the efficiencies of the power plant individual elements, by presenting its overall efficiency, may lead to the false conclusions.展开更多
700°C double reheat advanced ultra-supercritical power generation technology is one of the most important development directions for the efficient and clean utilization of coal.To solve the great exergy loss prob...700°C double reheat advanced ultra-supercritical power generation technology is one of the most important development directions for the efficient and clean utilization of coal.To solve the great exergy loss problem caused by the high superheat degrees of regenerative steam extractions in 700°C double reheat advanced ultra-supercritical power generation system,two optimization systems are proposed in this paper.System 1 is integrated with the back pressure extraction steam turbine,and system 2 is simultaneously integrated with both the outside steam cooler and back pressure extraction steam turbine.The system performance models are built by the Ebsilon Professional software.The performances of optimized systems are analyzed by the unit consumption method.The off-design performances of optimization systems are analyzed.The results show that:the standard power generation coal consumption rates of optimization systems 1 and 2 are decreased by 1.88 g·(kW·h)^(–1),2.97 g·(kW·h)^(–1)compared with that of the 700°C reference system;the average superheat degrees of regenerative steam extractions of optimized systems 1 and 2 are decreased by 122.2°C,140.7°C(100%turbine heat acceptance condition),respectively.The comparison results also show that the performance of the optimized system 2 is better than those of the optimized system 1 and the 700°C reference system.The power generation standard coal consumption rate and the power generation efficiency of the optimized system 2 are about 232.08 g·(kW·h)^(–1)and 52.96%(100%turbine heat acceptance condition),respectively.展开更多
High-temperature fatigue properties were investigated for a nickel-based superalloy 617 as a typical candidate material for high-temperature components using an advanced ultra super critical （A-USC） power plant. Cre...High-temperature fatigue properties were investigated for a nickel-based superalloy 617 as a typical candidate material for high-temperature components using an advanced ultra super critical （A-USC） power plant. Creep-fatigue data obtained by strain-controlled tests at 700 ？ C was analyzed for the superalloy 617 focused on position of hold at peak strain in comparison with continuously cycled tests. The fatigue life was the shortest with the hold tensile strain wave, which showed mainly intergranular fracture appearance. The life was the longest with symmetrical triangular wave which fractured from the specimen surface, while the wave with the hold compressive strain showed partially intergranular fracture appearance and the life was middle in the both waves. In this study, it is discussed with the creep-fatigue interaction for the superalloy 617.展开更多
Influence of Ti/Al ratios on the thermal stability of a new low cost Ni-Fe-Cr base wrought alloy,designed for application at 700℃ in advanced ultra-supercritical coal-fired power plants(700℃A-USC),was investigated b...Influence of Ti/Al ratios on the thermal stability of a new low cost Ni-Fe-Cr base wrought alloy,designed for application at 700℃ in advanced ultra-supercritical coal-fired power plants(700℃A-USC),was investigated both experimentally and thermodynamically. After standard heat treatment,the alloys with different Ti/Al ratios had the same microstructural characteristics. However,compared with the alloys with high Ti/Al ratio,the low Ti/Al ratio can increase the γ’-solvus temperature,decrease γ’ coarsening rate and reduce the temperature range of η phase precipitation. For the alloys with low Ti/Al ratio,the yield strength has no obvious decrease during long-term thermal exposure at 700 and 750℃,but after thermal exposure at 750℃ for 5000 h,the yield strength of the alloys with high Ti/Al ratio obviously decreases due to the η phase precipitation. The influence of h phase on mechanical properties is related with its size. When the h phase is small,it has no obvious influence on mechanical properties,but h phase becomes the crack initiation site with the further growth of η phase. It can be concluded that the decrease in Ti/Al ratio can improve the thermal stability to meet the requirement of 700℃ A-USC coal-fired power plants.展开更多
文摘Environmental pressures and economic requirements have led to a drive to ever increasing steam parameters to further increase steam turbine cycle efficiencies. This poses a number of challenges: plant architecture,steam turbine design and turbine material requirements. GE has been developing USC technology for more than 18 years and has many reference plants. The limits on inlet pressure and temperatures have been challenged as the technology and product development has proceeded. This paper discusses some of the options on how plant efficiency can be increased and some of the related challenges. The performance difference between a single reheat and double reheat is quantified based on a simplified thermodynamic model.
文摘In order to clarify the reason why the creep rupture time of pre-strained Ni-23Cr-7W Alloy (HR6W) is longer than that of the non-pre-strained HR6W, microstructures of HR6W after a series of creep tests were investigated. The creep tests were conducted at 750°C, 90 and 100 MPa. In the pre-strained samples, the grain boundary shielding ratio by precipitates was larger than that of the non-pre-strained sample. In addition, in the pre-strained samples the size of the M23C6 carbide in the grains was finer than in the non-pre-strained sample. The W content in the M23C6 carbide in the pre-strained samples tended to be larger than in the non-pre-strained sample. Therefore, the Ostwald ripening of the carbide was delayed and the size of M23C6 carbide was thought to be fine for a long time. These observations show that creep strength in the pre-strained samples is higher than that of the non-pre-strained sample because of both precipitation strengthening inside of the grains and grain boundaries.
基金The results presented in this paper were obtained from research work co-financed by the Polish National Centre of Research and Development in the framework of Contract SP/E/1/67484/10—Strategic Research Programme—Advanced technologies for energy generation:Development of a technology for highly efficient zero-emission coal-fired power units integrated with CO2 capture.
文摘The coal-fired power unit integration with a CO2 capture and compression installation involves a considerable rise in the costs of electricity generation. Therefore, there is a need for a continuous search for methods of improving the electricity generation efficiency in steam power plants. One technology which is especially promising is the advanced ultra-supercritical (A-USC) power unit. Apart from steam parameters upstream the turbine, the overall efficiency also depends on the efficiency values of individual elements of the plant and the size of energy consumption of the process of CO2 sequestration from the boiler flue gases. These problems are considered herein to emphasize that without specifying the efficiency values of the power plant main elements the information concerning its electricity generation efficiency is incomplete. This paper presents the influence of the efficiency of individual elements of the power plant on its electricity generation efficiency. The lack of information of the efficiencies of the power plant individual elements, by presenting its overall efficiency, may lead to the false conclusions.
基金financially supported by National key research and development program of China(No.2017YFB0602101,2018YFB0604404)。
文摘700°C double reheat advanced ultra-supercritical power generation technology is one of the most important development directions for the efficient and clean utilization of coal.To solve the great exergy loss problem caused by the high superheat degrees of regenerative steam extractions in 700°C double reheat advanced ultra-supercritical power generation system,two optimization systems are proposed in this paper.System 1 is integrated with the back pressure extraction steam turbine,and system 2 is simultaneously integrated with both the outside steam cooler and back pressure extraction steam turbine.The system performance models are built by the Ebsilon Professional software.The performances of optimized systems are analyzed by the unit consumption method.The off-design performances of optimization systems are analyzed.The results show that:the standard power generation coal consumption rates of optimization systems 1 and 2 are decreased by 1.88 g·(kW·h)^(–1),2.97 g·(kW·h)^(–1)compared with that of the 700°C reference system;the average superheat degrees of regenerative steam extractions of optimized systems 1 and 2 are decreased by 122.2°C,140.7°C(100%turbine heat acceptance condition),respectively.The comparison results also show that the performance of the optimized system 2 is better than those of the optimized system 1 and the 700°C reference system.The power generation standard coal consumption rate and the power generation efficiency of the optimized system 2 are about 232.08 g·(kW·h)^(–1)and 52.96%(100%turbine heat acceptance condition),respectively.
文摘High-temperature fatigue properties were investigated for a nickel-based superalloy 617 as a typical candidate material for high-temperature components using an advanced ultra super critical （A-USC） power plant. Creep-fatigue data obtained by strain-controlled tests at 700 ？ C was analyzed for the superalloy 617 focused on position of hold at peak strain in comparison with continuously cycled tests. The fatigue life was the shortest with the hold tensile strain wave, which showed mainly intergranular fracture appearance. The life was the longest with symmetrical triangular wave which fractured from the specimen surface, while the wave with the hold compressive strain showed partially intergranular fracture appearance and the life was middle in the both waves. In this study, it is discussed with the creep-fatigue interaction for the superalloy 617.
基金supported by the National High Technology Research and Development Program of China ("863 Program",No.2012AA03A501)the National Natural Science Foundation of China (No.51301171)+1 种基金the National Energy Administration Program of China (No.NY20110102-1)Chinese Academy of Sciences and Sichuan Province Cooperation Program
文摘Influence of Ti/Al ratios on the thermal stability of a new low cost Ni-Fe-Cr base wrought alloy,designed for application at 700℃ in advanced ultra-supercritical coal-fired power plants(700℃A-USC),was investigated both experimentally and thermodynamically. After standard heat treatment,the alloys with different Ti/Al ratios had the same microstructural characteristics. However,compared with the alloys with high Ti/Al ratio,the low Ti/Al ratio can increase the γ’-solvus temperature,decrease γ’ coarsening rate and reduce the temperature range of η phase precipitation. For the alloys with low Ti/Al ratio,the yield strength has no obvious decrease during long-term thermal exposure at 700 and 750℃,but after thermal exposure at 750℃ for 5000 h,the yield strength of the alloys with high Ti/Al ratio obviously decreases due to the η phase precipitation. The influence of h phase on mechanical properties is related with its size. When the h phase is small,it has no obvious influence on mechanical properties,but h phase becomes the crack initiation site with the further growth of η phase. It can be concluded that the decrease in Ti/Al ratio can improve the thermal stability to meet the requirement of 700℃ A-USC coal-fired power plants.
