针对我国目前普遍应用LSP工艺将低温分离器凝液直接进脱甲烷塔塔顶造成回流中重烃含量多、冷凝吸收效果差、乙烷回收率低的问题，提出2种低压（<2.2 MPa）外输气乙烷回收工艺：改进流程GAL，脱甲烷塔塔顶回流为低温分离器部分气相；改进流程FSP，部分原料气作为脱甲烷塔塔顶回流。研究了不同油田伴生气气质、不同原料气中CO₂摩尔分数对2种改进流程能耗、回收率的影响，以及原料气分流比对改进流程FSP能耗、回收率的影响。通过HYSYS软件对2种改进流程进行模拟，结果表明，在2种低压外输气改进工艺中FSP工艺对原料气中CO₂含量适应性更强。

In view of the widespread application of LSP process in China,low-temperature separator condensate enters directly into the top of the demethanizer tower,which resulting in high heavy hydrocarbon content in the reflux,poor condensation absorption effect,and low ethane recovery rate.According to the external gas transmission pressure level,two improved low pressure (<2.2 MPa) external gas ethane recovery processes are proposed:(1)the improved GAL process,in which the reflux from demethanizer column top is the low temperature separator part gas phase;(2)the improved FSP process,in which part of feed gas is used as the reflux of the demethanizer top.The effects of CO₂ content in different oilfields on the energy consumption and recovery rate of the two improved processes are studied,and the effect of the feed gas split ratio on the energy consumption and recovery rate of the improved FSP process are also investigated.Two improved processes are simulated by HYSYS software,showing that the improved FSP process is more adaptable to CO₂ content in the feed gas than the improved GAL process.