为了降低单一工艺中提氦的能量消耗及设备成本、使氮气循环膨胀制冷提供的冷量得到更加充分的利用,将自产冷剂制冷+膨胀制冷+冷箱集成换热的直接换热(DHX)轻烃回收工艺与天然气低温提氦工艺相结合,设计出一种可以同时生产C₃+、粗氦以及LNG的联产工艺。通过对关键参数影响因素分析,确定了膨胀机出口的压力为1.2 MPa、DHX塔顶回流温度为-70℃、一级提氦塔进料温度为-50℃、压缩泵出口压力为5 MPa、低温分离器进料温度为35℃、制冷剂流量为4 000 kmol/h。模拟计算得出,联产工艺C₃+回收率为78.95%、粗氦回收率为93.77%、粗氦浓度为60.43%、LNG产量为663.84 kmol/h。联产工艺与单一工艺相比总压缩机能耗降低了12.95%、单位综合能耗降低14.10%。研究表明,联产轻烃回收与LNG提氦工艺在能耗和投资成本方面具有较大优势,具有一定的经济价值。

In order to reduce the energy consumption and equipment cost of helium extraction in a single process and make full use of the cooling energy provided by nitrogen cycle expansion refrigeration,the direct heat transfer (DHX) process for light hydrocarbon recovery,with self-produced refrigerant refrigeration + expansion refrigeration + cooling box integrated heat transfer,is combined with the low temperature natural gas helium extraction process to design a co-production process for producing C₃+,crude helium and LNG simultaneously.Through analyzing the influencing factor of key parameters,it is determined that the pressure at the outlet of the expander is 1.2 MPa,the reflux temperature at the top of DHX tower is -70℃,the feed temperature for the first-stage helium-extracting tower is -50℃,the pressure at the outlet of the compression pump is 5 MPa,the feed temperature for the cryogenic separator is 35℃,and the refrigerant flow rate is 4 000 kmol·h^-1.Simulation results show that the recovery rate of C₃₊ is 78.95%,the recovery rate of crude helium is 93.77%,the concentration of crude helium is 60.43%,and the output of LNG is 663.84 kmol·h^-1.In addition,total compressor energy consumption of the co-production process is 12.95% lower than that of the single process,and the unit comprehensive energy consumption is 14.10% lower.Study shows that the light hydrocarbon recovery combined with LNG natural gas helium extraction process has great advantages in energy consumption and investment cost,presenting a certain investment value.