基于LNG冷能发电的ORC混合工质研究

Research on ORC mixed working mediums based on LNG cold energy power generation

对于低温有机朗肯循环(ORC),采用混合工质能有效提高系统性能。初选R170、R1150、R744、R1123、R32五种循环工质,从降低易燃风险、降低成本、提高运行稳定性三个方面对五种工质进行混配研究;结合LNG冷能发电工程项目,研究了冷、热源条件,蒸发侧、冷凝侧夹点温度对混合工质的影响。结果表明:混合工质R170/R744(0.8/0.2)具有较优的安全性,R1123/R32(0.6/0.4)具有较优的经济性,R170/R1150(0.6/0.4)具有较优的循环效率;以采用混合工质R170/R744的LNG冷能发电ORC系统为例,建议透平机出口干度设定为0.9,冷凝端夹点温度设定为15℃,蒸发端夹点温度设定为5℃。研究结果可为混合工质的应用提供必要的基础数据。

For the low-temperature organic Rankine cycle(ORC), the use of mixed working mediums can effectively improve the system performance. Five circulating working mediums, R170, R1150, R744, R1123 and R32, were initially selected, and they were studied from three aspects: reducing flammable risk, reducing cost and improving operation stability.Combined with the LNG cold energy power generation project, the effects of the cold and heat source conditions, the pinch point temperature of the evaporation side and the condensation side on the mixed working medium were studied. The results show that the mixed working medium R170/R744(0.8/0.2) has better safety, R1123/R32(0.6/0.4) has better economy, and R170/R1150(0.6/0.4) has better cycle efficiency.Taking the LNG cold energy power generation ORC system with mixed working medium R170/R744 as an example, it is recommended that the dryness of the turbine outlet be set at 0.9, the pinch point temperature of the condensation end be set at 15 ℃, and the pinch point temperature of evaporation end be set at 5 ℃. The research results can provide necessary basic data for the application of mixed working mediums.