Using the efficient,space-saving,and flexible supercritical carbon dioxide(sCO_(2)) Brayton cycle is a promising approach for improving the performance of nuclear-powered ships.The purpose of this paper is to design a...Using the efficient,space-saving,and flexible supercritical carbon dioxide(sCO_(2)) Brayton cycle is a promising approach for improving the performance of nuclear-powered ships.The purpose of this paper is to design and compare sCO_(2) cycle power systems suitable for nuclear-powered ships.Considering the characteristics of nuclear-powered ships,this paper uses different indicators to comprehensively evaluate the efficiency,cost,volume,and partial load performance of several nuclear-powered sCO_(2) cycles.Four load-following strategies are also designed and compared.The results show that the partial cooling cycle is most suitable for nuclear-powered ships because it offers both high thermal efficiency and low volume and cost,and can maintain relatively high thermal efficiency at partial loads.Additionally,the new load-following strategy that adjusts the turbine speed can keep the compressor away from the surge line,making the cycle more flexible and efficient compared to traditional inventory and turbine bypass strategies.展开更多
Using supercritical carbon dioxide(S-CO2)Brayton cycle instead of the traditional steam Rankine cycle is a promising technique to enhance the coal-fired power generation efficiency.Researchers from all over the world ...Using supercritical carbon dioxide(S-CO2)Brayton cycle instead of the traditional steam Rankine cycle is a promising technique to enhance the coal-fired power generation efficiency.Researchers from all over the world are actively designing and exploring efficient S-CO2 coal-fired power plants in recent years with great efforts made to overcome the significant technical challenges in the cycle layouts of S-CO2 and its specific thermal integration with coal-fired heat resources.This paper provides a detailed review of the research progress on the coal-fired power generation using S-CO2 Brayton cycles.The basic knowledge of S-CO2 properties,the promising S-CO2 power cycles and the conceptual designs for S-CO2 coal-fired power plants are comprehensively summarized,with some key issues in the constructing process and the corresponding engineering solutions being emphatically discussed.Based on the current achievements,the overall technical and economic evaluations on the S-CO2 coal-fired power system are figured out.Furthermore,the specific integration applications of S-CO2 cycles with different coal firing devices and modes including pulverized coal combustion,circulating fluidized bed combustion,oxy-coal combustion,pressurized fluidized bed combustion,chemical looping combustion are discussed.Finally,the main challenges requiring further studies are highlighted.展开更多
Supercritical carbon dioxide(S-CO_2) Brayton power cycle is a competitive technology to achieve high efficiency in a variety of applications. However, in coal power applications, the CO_2 generated from coal combustio...Supercritical carbon dioxide(S-CO_2) Brayton power cycle is a competitive technology to achieve high efficiency in a variety of applications. However, in coal power applications, the CO_2 generated from coal combustion still discharges into the atmosphere causing a series of environment problems. In this work, an 300 MWe S-CO_2 power cycle with circulating fluidized bed(CFB) oxy-coal combustion was established including air separation unit(ASU), CFB boiler, recuperator system and carbon dioxide compression and purification unit(CPU). Based on the material and energy conservation, the cycle efficiency of S-CO_2(620°C, 25 MPa) Brayton power cycle with CFB oxy-coal combustion is evaluated compared to the oxy-coal combustion steam Rankine cycle and S-CO_2 Brayton power cycle with the 31.65 kg/s coal supply. After that, the influence of several factors, e.g., exhaust flue gas temperature, split ratio in recuperator system and the oxygen supply on the cycle efficiency was investigated and analyzed. The results show that the net efficiency of S-CO_2 power cycle with CFB oxy-coal combustion(32.67%) is much higher than the steam Rankine cycle utilizing CFB with 17.5 Mpa, 540°C steam(27.3%), and 25 Mpa, 620°C steam(30.15%) under the same exhaust flue gas temperature. In addition, lower exhaust flue gas temperature and higher split ratio are preferred to achieve higher cycle efficiency. Lower oxygen supply can reduce the energy consumption of ASU and CPU, further increasing the system net efficiency. However, the energy losses of ASU and CPU are still very large in oxy-coal combustion and need to be improved in further work.展开更多
基金supported by the National Natural Science Foundation of China (52276150)。
文摘Using the efficient,space-saving,and flexible supercritical carbon dioxide(sCO_(2)) Brayton cycle is a promising approach for improving the performance of nuclear-powered ships.The purpose of this paper is to design and compare sCO_(2) cycle power systems suitable for nuclear-powered ships.Considering the characteristics of nuclear-powered ships,this paper uses different indicators to comprehensively evaluate the efficiency,cost,volume,and partial load performance of several nuclear-powered sCO_(2) cycles.Four load-following strategies are also designed and compared.The results show that the partial cooling cycle is most suitable for nuclear-powered ships because it offers both high thermal efficiency and low volume and cost,and can maintain relatively high thermal efficiency at partial loads.Additionally,the new load-following strategy that adjusts the turbine speed can keep the compressor away from the surge line,making the cycle more flexible and efficient compared to traditional inventory and turbine bypass strategies.
基金Financial support from the National Key Research and Development Program of China(No.2017YFB0601802)Key Research and Development Program of Jiangsu Province(No.BE2017159)。
文摘Using supercritical carbon dioxide(S-CO2)Brayton cycle instead of the traditional steam Rankine cycle is a promising technique to enhance the coal-fired power generation efficiency.Researchers from all over the world are actively designing and exploring efficient S-CO2 coal-fired power plants in recent years with great efforts made to overcome the significant technical challenges in the cycle layouts of S-CO2 and its specific thermal integration with coal-fired heat resources.This paper provides a detailed review of the research progress on the coal-fired power generation using S-CO2 Brayton cycles.The basic knowledge of S-CO2 properties,the promising S-CO2 power cycles and the conceptual designs for S-CO2 coal-fired power plants are comprehensively summarized,with some key issues in the constructing process and the corresponding engineering solutions being emphatically discussed.Based on the current achievements,the overall technical and economic evaluations on the S-CO2 coal-fired power system are figured out.Furthermore,the specific integration applications of S-CO2 cycles with different coal firing devices and modes including pulverized coal combustion,circulating fluidized bed combustion,oxy-coal combustion,pressurized fluidized bed combustion,chemical looping combustion are discussed.Finally,the main challenges requiring further studies are highlighted.
基金supported by the National key research and development program of China (project number: 2017YFB0601802)the project of the National Natural Science Foundation of China (project number: 51876037)the Key Research and Development Program of Jiangsu Province, China (No.BE2017159)
文摘Supercritical carbon dioxide(S-CO_2) Brayton power cycle is a competitive technology to achieve high efficiency in a variety of applications. However, in coal power applications, the CO_2 generated from coal combustion still discharges into the atmosphere causing a series of environment problems. In this work, an 300 MWe S-CO_2 power cycle with circulating fluidized bed(CFB) oxy-coal combustion was established including air separation unit(ASU), CFB boiler, recuperator system and carbon dioxide compression and purification unit(CPU). Based on the material and energy conservation, the cycle efficiency of S-CO_2(620°C, 25 MPa) Brayton power cycle with CFB oxy-coal combustion is evaluated compared to the oxy-coal combustion steam Rankine cycle and S-CO_2 Brayton power cycle with the 31.65 kg/s coal supply. After that, the influence of several factors, e.g., exhaust flue gas temperature, split ratio in recuperator system and the oxygen supply on the cycle efficiency was investigated and analyzed. The results show that the net efficiency of S-CO_2 power cycle with CFB oxy-coal combustion(32.67%) is much higher than the steam Rankine cycle utilizing CFB with 17.5 Mpa, 540°C steam(27.3%), and 25 Mpa, 620°C steam(30.15%) under the same exhaust flue gas temperature. In addition, lower exhaust flue gas temperature and higher split ratio are preferred to achieve higher cycle efficiency. Lower oxygen supply can reduce the energy consumption of ASU and CPU, further increasing the system net efficiency. However, the energy losses of ASU and CPU are still very large in oxy-coal combustion and need to be improved in further work.
