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《Journal of Xi'an Jiaotong University》 2018-09
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Novel System Design for a 300MW Single Reheat Subcritical Coal-Fired Power Plant

LI Qinlun;WANG Lukai;LIU Yinhe;CHE Defu;State Key Laboratory of Multiphase Flow in Power Engineering,Xi'an Jiaotong University;  
For conventional 300 MW single reheat subcritical coal-fired power plants,the heat transfer temperature difference between flue gas and air in the air preheater is large,resulting in a large exergy loss.Moreover,the sulfuric acid vapor easily condenses on the cold side,which causes low-temperature corrosion and ash plugging on the heated surface.In the regenerative system,the heat transfer temperature difference between the extraction steam and the condensate water at the hot end of regenerative heater(RH)is large,and the superheat degree of the extraction steam is difficult to use.To solve these problems,a novel conceptual system design for the conventional power plants is proposed.Thermodynamic analysis and techno-economic analysis of the proposed plant are performed.In the proposed system,air preheater in conventional power plant is completely replaced by flue gas-condensate preheater(FGCP),all the flue gas from theeconomizer is used to heat partial condensate in FGCP,total air together with the rest of the condensate is preheated by extraction steam,and an extra steam bleed is added to ensure that the air temperature meets the design requirement.The results show that keeping heat-capacity flowrate of the partial condensate equal to that of flue gas in FGCP can avoid the pinch point of temperature difference of conventional air preheater,and the exit temperature of flue gas from boiler can be reduced to 130℃ without cold end corrosion and clog.Steam and air heaters are arranged in series after corresponding RHs,and total air is preferentially heated by extraction steam,which reduces the heat transfer temperature difference between the steam and the condensate.The power generation efficiency and the net power generation efficiency of the novel power plant are 45.34% and 44.20% respectively,increasing 1.2 and 1.0 percentage points compared with that of the conventional unit at the same capacity.The dynamic investment payback period of the modified power plant is about 4.27 years,which is feasible.
【Fund】: 国家自然科学基金资助项目(51576158)
【CateGory Index】: TM621
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