利用氢气分离膜降低乙烯深冷系统制冷压缩机的功耗

Reducing refrigeration compressor power in chilling process of ethylene plant by using hydrogen separation membrane

针对传统乙烯过程中深冷脱氢工艺冷凝温度低、能耗大的问题,基于某800 kt/a乙烯的裂解气脱氢装置,提出了两级膜与深冷耦合回收乙烯裂解气中氢气的流程,利用Uni Sim Design软件对新流程进行了模拟分析,确定了两级膜面积分别为28000m^2和10110m^2。由于第一级膜分离装置回收了裂解气中的部分氢气,显著地减少了深冷系统中制冷压缩机的功耗和脱甲烷塔塔顶的乙烯损失,新流程深冷系统的制冷压缩机功耗为39496 k W,比原流程减少了8996k W,乙烯损失率由1.29%降低到0.46%。第二级膜分离装置实现了氢气回收的高纯度(99%)和高回收率(98.52%),获得的氢气产品可以直接并入氢网或用于对氢气浓度要求较高的加氢裂化装置中。

The chilling process of traditional ethylene process has several disadvantages,including low condensation temperature,which requires significant amount of energy. To recover hydrogen from an ethylene plant of 800 kt/a,a hybrid process combining two-stage hydrogen separation membrane and cryogenics was proposed. Based on simulation and optimization with the Uni Sim Design software,the optimal conditions of this membrane system were identified,i.e,membrane areas in two stages were 28000m^2 and 10110m^2,respectively. In conclusion,refrigeration compressor power and ethylene loss were significantly decreased because part of hydrogen was recovered by the first-stage membrane system. The compressor power in the chilling process was 39496 k W,8996 k W lower than that in the traditional process. The ethylene loss of demethanizer overhead decreased from 1.29% to 0.46%. H_2 product with high concentration（99%） and high recovery（98.52%） was achieved through the second-stage membrane system,which could merge into hydrogen network directly or be used for hydrocracking with higher demand for hydrogen concentration.