液化天然气冷能回收系统的性能分析

Liquefied natural gas (LNG) will produce a lot of cold energy into conventional natural gas in the gasification, which can be used for power generation in the LNG gasification process by the use of thermal cycling work, improving energy efficiency. In this paper, the industrial waste heat of 250℃ was used as the heat source, and the LNG was used as the cold source. A joint Rankine cycle containing LNG direct expansion and Rankine thermal cycle was established by Aspen plus software simulation. Eight kinds of organic pure working materials such as R23, R290 and R134a were compared and screened, analyzing the latent heat of vaporization, the temperature of condensation and the specific work, exergy efficiency and thermal efficiency in the cycle. The result shows that R170, R290 and R1270 have better performance in the cycle, and taking into account the safety of the pump and the exergy economy, the final evaluation of R290 is the best. With R290 as the Rankine cycle working fluid, the performance of the combined cycle is analyzed under the conditions of different maximum circulating pressure, heat source temperature, heat source flow and working fluid flow, taking the exergy destruction, exergy efficiency and thermal efficiency as the evaluation index. And finally determining the highest efficiency of the cycle parameters, analyzing of the flow of the current conditions and the exergy destruction of the components, found that the largest component of the loss is the heat exchanger equipment, the exergy destruction of pump is relatively minimal.