Abstract:

The performance of MTO olefin separation process directly affects the quality of target product and the overall benefits. The previous cryogenic separation processes are gradually replaced by the inter-cooling separation processes because of process complex and high energy consumption. In the paper, several industrial separation processes for front-end depropanization are compared and discussed by process simluation. The result indicates that big discrepancies at the different processes are localized in the systems of depropanizer and demethanizer. The double-tower type of high and low pressure depropanizers can reduce the energy comsumption compared with the double-tower type of condensate stripping tower and depropanizer. For the demethanizer, the amount of absorbent in the single demethanizer type is more than that in the double-tower type of pre-segmentation and oil-absorption and the double-section single-tower type of oil-absorption and stripping. At present, the long circulation loop of absorbent in those existing processes increases working load and investment of each tower in the loop. Thus, a new design to short circulation loop of absorbent can reduce the tower equipment investment without increasing energy consumption.

Key words: methanol to olefins, front-end depropanizer separation process, simulation, equation of state, energy consumption, equipment investment, optimal design

摘要：

甲醇制烯烃（MTO）分离流程的性能直接影响目标产品质量和整体收益。早期MTO深冷分离流程复杂、能耗高，已逐渐被现有中冷油吸收分离流程所取代。通过流程模拟，本文对比考察了几种已工业应用的MTO前脱丙烷分离流程。结果表明，现有MTO前脱丙烷分离流程主要差异在于脱丙烷系统和脱甲烷系统；脱丙烷系统中采用高、低压脱丙烷塔，较凝液汽提塔+脱丙烷塔型式可节省能耗；脱甲烷系统中采用预切割-油吸收双塔或油吸收-汽提双段单塔型式，较单脱甲烷塔型式可节省丙烷吸收剂用量（约29%）。现有流程都存在吸收剂循环回路过长导致循环内各塔操作负荷和设备投资增大问题。由此，提出的一种吸收剂短回路MTO前脱丙烷分离流程，可在不增加能耗的基础上，降低塔设备投资。

关键词: 甲醇制烯烃, 前脱丙烷分离流程, 模拟, 状态方程, 能耗, 设备投资, 优化设计