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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.10 Schematic diagram of front-end deethanizer separation process (C4S as absorbent, non-clear cutting)
Extracts from the Article
在图10所示流程中,脱乙烷塔对碳三进行部分切割,让一部分碳三从脱乙烷塔塔顶进入脱甲烷塔,以减小塔顶回流回路中产品气压缩机第四段和冷箱的功率或负荷,吸收塔塔底的富吸收剂以回流形式进入脱甲烷塔塔顶,脱甲烷塔底物料进第二脱乙烷塔;第二脱乙烷塔塔顶物料去乙烯精馏塔得到合格的乙烯产品,塔底物料去脱丙烷塔;脱丙烷塔塔顶物料经丙烯精馏塔得到合格的丙烯产品,塔底物料去脱丁烷塔;脱丁烷塔塔顶得到混合碳四C4S,塔底得到混合碳五C+5
图10所示分离技术存在以下循环回路。
对图10所示流程进行模拟计算、优化操作参数和换热网络,产品气压缩机和丙烷压缩机功耗、装置的冷却水和蒸汽消耗见表4。表4包括了前脱乙烷清晰切割和非清晰切割两种流程的公用工程消耗对比,图11是两种分离流程标准燃料油消耗对比,为便于比较,假设脱乙烷塔回流量为600 kmol/h。
对图12流程进行模拟计算、优化操作参数和换热网络,双机功耗、冷却水和蒸汽消耗见表5,图10和图12所示前脱乙烷流程标准燃料油消耗对比见图13。
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