三种混合制冷剂循环液化天然气的比功耗和对比

Comparison of Unit Power Consumption and Exergy for Mixed Refrigerants Cycle to LNG

针对利用混合制冷剂循环液化天然气技术能降低循环功耗及提高?效率的特点,通过建立模拟的无预冷混合制冷剂循环、三级丙烷预冷混合制冷剂循环和单级丙烷预冷混合制冷剂循环3种天然气液化模型,在一定约束条件下模拟计算液化过程压缩机的比功耗、损失及制冷剂流量,对比分析压缩机的比功耗和损失。结果表明:无预冷混合制冷剂循环的比功耗和损失量都是最大的,其比功耗分别是三级丙烷预冷混合制冷剂循环的7.28倍、单级丙烷预冷混合制冷剂循环的7.23倍,其损失量是三级丙烷预冷混合制冷剂循环的10.74倍、单级丙烷预冷混合制冷剂循环的10.62倍;但单级丙烷预冷混合制冷剂循环较三级丙烷预冷混合制冷剂循环有流程更简单、更便于维护的优势。因此应优先选用单级丙烷预冷混合制冷剂循环液化流程。

The technology of mixed refrigerant cycle to LNG may not only reduce power consumption but also improve exergy efficiency. So, three models of liquefaction process were developed, including mixed refrigerant cycle without pre-cooling, and singlestage and three-stage propane-precooled mixed refrigerants cycle.Under the condition of certain constraints, these models were used to simulate and calculate the unit power consumption, exergy loss,and refrigerant flow of the air compressor. Furthermore, unit power consumption and exergy loss were analyzed. Results show that(1)for the mixed refrigerant cycle without pre-cooling, its unit power consumption and exergy loss are the biggest ones among these of single-stage and three-stage propane-precooled mixed refrigerants cycle 7.28 times and 10.74 times of three-stage one, and 7.23 times and 10.62 times of one-stage one, individually; and(2)single-stage one is superior to three-stage one owing to simpler process and more easy maintenance. In general, the single-stage propane-precooled mixed refrigerant cycle should be optimally selected.