低温余热有机朗肯循环发电系统热经济性分析

摘要

针对工业中排放的低温烟气,建立有机朗肯循环发电系统的热经济分析模型,分析蒸发压力、热源温度及蒸发器最小传热温差对系统经济性能的影响.分析结果表明:热源温度为140℃,循环采用R123的经济性最佳,相应的发电成本与动态投资回收期分别为0.142元/(kW.h)与3.68年.余热发电系统存在一个经济性最高的蒸发压力,不同工质对应的最佳蒸发压力也不同.蒸发器内最小传热温差为15℃时,系统的经济性较好.烟气温度在100～180℃时,系统采用R123的投资回收期最短,而烟气温度高于180℃时,R141b的经济性更高；不宜采用有机朗肯循环发电技术回收温度低于100℃的低温烟气.%An thermo-economic analysis model was developed for the power generating using the low temperature exhaust from industry.According to the model,the effect of evaporation pressure,waste heat temperature and minimum temperature difference in evaporator on the economic performance was presented.The results show that when the temperature of exhaust is 140 ℃,system with R123 can achieve the most economic performance.The corresponding electricity production cost and payback period of system is at 0.142 yuan/(kW · h)and 3.68 years respectively.There is an optimal evaporation pressure for ORC system in order to get better economic performance and the optimal pressure varies with working fluids.In order to shorten the payback period,the optimal temperature difference.in evaporator is about 15 ℃.Compared with other working fluids,R123 is the best choice for the temperature range at 100 ～ 180 ℃and Rl41b shows better performance when the temperature higher than 180 ℃.When the temperature of exhaust is lower than 100 ℃,ORC system is uneconomical.