催化轻汽油醚化技术的应用与研究

Application and research of FCC light gasoline etherification technology

关键词:  轻汽油醚化  原料预处理  反应器  内构件  醇烯比  甲醇回收系统  腐蚀

Key words:  light gasoline etherification  feed pretreatment  reactor  internal  methanol to olefin molar ratio  methanol recovery system  corrosion

摘要:

催化轻汽油醚化工艺是一种清洁汽油生产工艺,在提高催化汽油辛烷值的同时,可降低其烯烃含量。重点讨论了催化轻汽油醚化工艺在原料预处理、醚化反应、甲醇回收方面的一些应用与研究成果。结果 表明:①原料预处理采用微萃取深度分离设备代替常规水洗塔,可降低水洗水用量；②醚化反应优先选用“两台醚化反应器串联+共沸塔+醚化反应器”流程；③醚化反应器内件采用条缝筛网代替不锈钢孔板和丝网可避免石棉绳脱落等事故的发生；④醇烯比与轻汽油进料组成及共沸塔或催化蒸馏塔的操作压力有关,其取值范围可在1.2~1.5；⑤甲醇和催化轻汽油进料采用比值控制方案,当进料中活性烯烃含量变化不大时,可取消控制方案中价格昂贵的在线分析仪；⑥采用萃取精馏法对C₅组分与甲醇分离存在设备和管线腐蚀问题,解决的主要措施是在萃取水管线上设置净化器。另外,共沸塔侧线抽出-反应-分离工艺和变压精馏工艺因不使用萃取水,在降低设备和管线腐蚀的同时不向外界排放难以处理的含甲醇污水,值得大力推广。 

Abstract:

FCC light gasoline etherification process is a clean gasoline production process which can improve the octane number of FCC gasoline while reducing its olefin content. This paper focuses on some applications and research results in feed pretreatment, etherification reaction and methanol recovery. The results showed as follows:(1) Using the microextraction-colescence separation equipment instead of the conventional washing towers for feed pretreatment could greatly reduce the washing water flow. (2) "Two etherified reactors in series + one azeotropic tower + one etherified reactor” was one preferred etherification process. (3) Stainless steel orifice plate and wire mesh could be replaced by Johnson screen in etherified reactor in order to avoid the accidents such as the fall-off of the asbestos ropes. (4) The methanol to olefin molar ratio which is between 1.2 and 1.5 was related to the composition of light gasoline feed and the operating pressure of azeotropic column or catalytic distillation column. (5) The ratio control scheme was adopted for methanol and catalytic light gasoline feeding, and the expensive on-line analyzer could be cancelled in the control scheme when the content of active olefins in the feed was not greatly changed. (6) There were corrosion problems in equipment and pipelines for separation of methanol and C₅ by extraction distillation, and the main measure was setting up purifiers on the extraction pipelines. In addition, as side draw-reaction-separation process and pressure swing distillation process of azeotrope tower did not use extraction water, which could reduce the corrosion of equipment and pipelines without discharging refractory methanol-containing sewage to the outside world, and therefore it was worthy of great popularization.