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Research and optimization of separation technology of methanol to propylene
Zizong WANG, Hongqian LIU, Jiming WANG
CIESC Journal    2019, 70 (1): 136-145.   DOI: 10.11949/j.issn.0438-1157.20171033
Abstract   (564 HTML20 PDF(pc) (925KB)(199)  

Based on the actual equipment of 1.7 million tons/year methanol to propylene (MTP), this paper studies and optimizes the MTP separation process, draws on the experience of separation of naphtha ethylene unit, and optimizes the formation characteristics of MTP product gas. The process combination, process simulation and optimization of the separation technology are carried out together with de-methanizer tower and its exhaust gas recovery system, highly thermal coupling decarburization system (de-ethanizer and ethylene rectifying column), sorbent selection, and screen out a more suitable separation technology consisting of the following process unit: pre-cutting front-end deethanizer, recovery of de-methanizer tail gas by combination of intercooling oil absorption and throttle expansion, highly thermally coupled deethanizer system, take carbon four mixture as absorbing agent, etc.Assuming that there are no ethylene, carbon four and carbon five cycles back to the MTP reactor, the ethylene loss in the exhaust meets the design requirements, using the optimized separation technique, the dual power of the compressor and propylene compressor is 19.8 MW. The simulation results show that the optimized flow has a good application prospect.

Fig.3 Schematic diagram of front-end deethanizer separation technique (C3H8 as absorbent)
Extracts from the Article
优化的前脱乙烷分离流程如图3所示,来自反应器的产品气经压缩、净化后,以气液两相形式入脱乙烷塔;脱乙烷塔对产品气进行清晰切割,塔顶物料压缩升压、冷却后进脱甲烷塔,塔底物料进脱丙烷塔; 脱甲烷塔塔顶尾气经中冷油吸收、膨胀节流回收乙烯后去燃料气系统,塔底物料进乙烯精馏塔分离得到聚合级乙烯产品;脱丙烷塔顶物料去丙烯精馏塔分离得到聚合级丙烯产品,塔底物料去脱丁烷塔;脱丁烷塔塔顶得到混合碳四,塔底得到混合碳五及以上更重组分。
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