两种乙烷回收新流程的热力学对比分析

Thermodynamic analysis of two new ethane recovery processes

现今国内油气田大力倡导发展天然气乙烷回收工程建设以提升油气田经济效益。基于此背景下改进设计出两种高效乙烷回收新流程:(1)带丙烷制冷的RSV流程(RPC);(2)带吸收塔和自冷循环的分流预热乙烷回收流程(SPAS)。经模拟及热力学分析,两种流程主要差别有:(1)相比于RPC流程,SPAS流程取消了干气回流,外输压缩机功耗更低;(2)SPAS采用内部自冷循环制冷,原料气预冷换热冷箱中物流温位匹配更合理,热集成度更优;(3)SPAS两级自冷循环压比较RPC流程丙烷制冷系统两级压比更均匀,SPAS流程的制冷循环压缩机负荷较RPC流程更低。综合看来,创新设计的SPAS流程相较于改进的RPC流程热力学性能更佳。

Nowadays China's oil and gas fields vigorously advocate the development of natural gas ethane recovery project to improve their economic benefits.On this background,two efficient processes for ethane recovery are designed innovatively:(1)recycle split vapor process with propane cycle(RPC);(2)split preheating ethane recovery process combined with absorber and selfcooling cycle(SPAS).Through simulation and thermodynamic analysis,it is found that the two processes have the following differences:(1)compared with RPC process,the SPAS process cancels the residue gas recycle,which makes the residue gas compressor consume less power;(2)SPAS adopts self-refrigeration cycle,and its multi-stream precooled heat exchanger has more reasonable temperature matching,and its thermal integration is better than that of RPC process;(3)the two-stage self-cooling cycle pressure ratio of SPAS is more uniform than that of the propane refrigeration system of the RPC process,and the power of refrigeration compressors of the SPAS process is much lower than that of the RPC process.In summary,the thermodynamic performance of the innovatively designed SPAS process is better than that of the improved RPC process.