Ethylene Recovery From Refinery Gas By Adsorption And Distillation Process

This article introduced the importance of ethylene in national economy and analized the internatinal and domestic market demand. According to the demands exceeds supply of ethylene and the combination of oil refinery and chemical, this article put forward a new separation process to recovery the refinery gas. The recoverd C2 above will be used as complementary feed for ethylene plant or polymer grade ethylen will be used as chemical raw material.This article continued to introduce several separation processes such as cryogenic process, expander process, ARS process, middle low temperature oil absoption process, complexation process and chemical adsorption process etc.. It also analized the main reason that why these process had not been extended in the aspect of the recovery of olefin, raw material, assistant material and energy consumption. Under the advantages of cryogenics process and physical adsorption process, it put forward a low energy consumption process named adsorption-distillation process.The article explained the characters of adsorption-distillation process. Compared with Jrie cryogenics process, the adsorption-distillation process saved a large amount of compression energy, the scale and investment on purification would be reduced for the treated gas flow decreased to 20-30% of refinery gas, the grade of coolant decreased eighter, the refrigenerting cycle became simple, the physical adsorbent had been used in large scale PSA plant.The article decribed the process of recovery of refinery gas. The refinery gas was diveded into two part, one was enriched with H2, O2, N2, CO CH4 named Hz enriched distillate, and the other was enriched with C2H4, C2H6, C3H6,C3H8, C4, C4 above and CO2 which named C2H4 enriched distillate. The acide gas in the C2H4 enriched distillate then was removed by the sequence of amine absorption, NaOH absorption, hydrogeneratin, desiccation etc.. At last the polymer grade of ethylene could be get by superficial low temperature distillation.Theoretic analysis and mathematic model has been made on every unit consists of adsorption-distillation process such as pressure swing adsorption, compression, acid gas removal by amine and NaOH, selectivity hydrogeneration, desiccation, CH4 removal and C2H4 distillation etc.. The inner process selection and inner process organizatin had been introduced.The refinery gas of maoming division of SINOPEC which has 13500kt/a oil refining scale had been separated by simulation design through ASPEN PLUS simuatin program. Several optimization has been made such as the combinatin of adsorption and distillation, acid gas removal, CH4 removal tower and CH4 distillation tower etc.. At last the energy consumption had been analized and the investment estimate had been made.Under the simulatin design and the comparation of other process, the adsorption-distillation process had the advantages of low energy consumption and investment with mature technique. It has important extension signification. It will play an important acceleration role on refinery gas synthetic utilization and the combinatin of oil refinery and chemical industry.