基于分壁精馏塔的乙烯装置顺序分离新工艺及其模拟研究

A New Sequential Separation Process and Its Simulation for Ethylene Plant Based on a Dividing Wall Column

改进了乙烯装置顺序分离流程,将传统流程中的脱甲烷塔和脱乙烷塔集成为1个分壁精馏塔,实现C1、C2和C3+的分离,再分别经脱丙烷塔、炔烃选择加氢器、乙烯精馏塔、丙烯精馏塔等,得到聚合级的乙烯和丙烯产品。利用Aspen对分壁精馏塔进行等效模拟,并对新工艺进行全流程模拟。模拟结果表明,分壁精馏塔塔板数为43,进料在第17块板,侧线采出在第13块板,回流比2.6,隔板处于第7到第29块板之间,塔顶采出物中C1质量分数为99.94%,中间侧线采出物中C2的质量分数为99.97%,塔底釜液中C3+的质量分数为100%,实现了C1、C2和C3+的清晰分割。采用该新工艺可以得到质量分数分别为99.97%和99.98%的聚合级乙烯和丙烯产品,因此,建立的基于分壁精馏塔的乙烯装置顺序分离新工艺在技术上可行。

Sequential separation process of the ethylene plant was improved, in which the demethanizer and deethanizer were integrated into a dividing wall column in order to separate C1, C2 and C3＋. Finally, polymerization grade ethylene and propylene were obtained through depropanizer, hydrotreater of alkyne, ethylene rectifier and propylene rectifier. Equivalent simulation of dividing wall column and full process simulation were carried out by Aspen software. The simulation results indicated that plate number of dividing wall column was 43, feed inlet was at 17th plate, side product outlet was at 13th plate, reflux ratio was 2.6, and the dividing wall was located from 7th to 29th plate. At these parameters, C1 content in the top product was 99.94%, C2 content in the side product was 99.97%o and C3＋ content in the bottom product was 100%. It is suggested that a clear separation of C1, C2 and C3＋ was achieved by using the dividing wall column. The mass fraction of ethylene product and propylene product obtained by the new separation process could reach 99.97% and 99.98%, respectively, both of which achieved the polymerization grade, indicating that the new separation process for ethylene plant based on dividing wall column designed in this study was feasible in technology.