有机工质余热发电系统的经济性分析

Economic Analysis of Waste Heat Power Generation System of Organic Rankine Cycle

由于有机工质余热发电系统的经济性是影响该技术推广应用的关键因素,本文对系统的经济性进行分析研究。以蒸发温度、蒸发器窄点温差、余热介质流量及冷却水流量为自变量,建立了以最小电力生产成本为目标函数的优化模型;分析了各参数对系统电力生产成本的影响,并以6种有机工质为例,对系统进行了参数优化;且比较了余热温度对最佳参数的影响。结果表明:由于蒸发温度、蒸发器窄点温差、余热介质及冷却水流量对系统设备造价和净输出功的综合影响,其均存在最佳值使电力生产成本最小;在余热介质进口温度170℃和冷却水进口温度20℃时,工质R245fa的经济性最好,对应的最小电力生产成本约0.433 9元/(k W·h);且随着余热介质进口温度的升高,系统经济性提高,对应的最佳蒸发温度、蒸发器窄点温差及余热介质流量均增大。

The system economy, a key factor influencing the popularization and application of waste heat power genera- tion of organic rankine cycle, was analyzed in this paper. The evaporating temperature, pinch point temperature differ- ence, waste heat and cooling water flow were selected as independent variables to establish the optimization mode, in which the minimum electric production cost was the objective function. And the influence of different parameters on e- lectric production cost was analyzed. Six working fluids were taken as examples to optimize the system parameters. In addition, the influence of water heat temperature on optimal parameter was compared. The results showed that while the evaporating temperature, pinch point temperature difference, waste heat and cooling water flow had a comprehensive in- fluence on net output and equipment cost, there existed optimal values to make electric production cost a minimum. The economy of R245fa was the best at waste heat 170℃and cooling water 20℃ , when the corresponding electric pro- duction cost was about 0. 4339 yuan/ （kW · h）. And also, with the rise of waste heat inlet temperature, the best e- vaporating temperature, pinch point temperature difference, and waste heat flow increased, and the system economy was also improved.