冷剂制冷-油吸收复合凝液回收工艺的应用

Application of the Cryogen Refrigeration-Oil Absorption Combination Process for NGL Recovery

为了进一步提高天然气凝液装置的产品收率,本文针对凝析气田中气源压力高,无压差可利用的工况条件,应用冷油吸收原理,通过工艺流程模拟分析与研究,确定了冷剂制冷-油吸收复合凝液回收工艺原理流程。通过流程模拟,分析了影响丙烷回收率的主要因素。本文实例研究表明:相同制冷温度下,冷剂制冷-油吸收复合工艺的丙烷回收率比原冷剂制冷工艺可提高23%～27%。适当提高吸收塔的压力,对增大丙烷回收率有利,但吸收塔压力的确定要综合考虑原料气压力和外输气压力的大小。吸收剂循环流量对丙烷回收率、两塔热负荷的影响是十分显著的,吸收剂循环流量越大,丙烷收率越高,但吸收剂流量增大到一定值后,丙烷回收率增加量变缓,同时脱乙烷塔、塔冷凝器以及重沸器热负荷显著增加,吸收剂循环流量比控制在0.7～0.75之间比较合理。

In order to improve the NGL recovery rate for some condensate gas fields, which had high pressure gas source and there was no differential pressure for utilization, this paper put forward a cryogen refrigeration-oil absorption combination process to recover NGL on the basis of cold oil absorption theory. By the simulation of process flow, the main factors which effected propane recovery rate were studied. It showed that the propane recovery rate of new process would be 23%～27% higher than that of cryogen refrigeration process at the same refrigeration temperature. To increase the absorption tower pressure appropriately was good to improve the propane recovery rate. However, the choice of pressure must take the pressure of the feed natural gas and product gas into account together.The flow rate of absorbent had great effect on propane recovery rate and tower heat load. The propane recovery rate would become greater and greater with the increase of absorbent flow rate. But, when the circulating flow rate of absorbent increased to a certain value, the improvement of propane recovery rate will be slow down. At the same time, heat load of the deethanizer, condenser and reboiler would increase drastically. So circulating flow rate ratio of absorbent should be adjusted between 0.7 and 0.75.