异丁烯选择性叠合工业化装置工艺流程优化与节能措施

Process flow optimization and energy saving measures of an industrialized isobutylene selective dimerization unit

关键词:  异丁烯选择性叠合  水洗  共沸物  外循环回路  变压精馏  三塔流程  TBA  二异丁烯 

Key words:  isobutene selective dimerization  water washing  azeotropes  external circulating loop  pressure-swing distillation  three-tower process  TBA  diisobutylene

摘要:

目的 对某异丁烯选择性叠合工业化装置工艺流程进行优化。方法 ①增加水洗塔,用于脱除C₄原料中金属阳离子和碱氮化合物；②取消将TBA直接注入至催化蒸馏塔的管道和相关设备；③采用包含“催化蒸馏塔+高压塔+低压塔”的三塔变压精馏流程对TBA-二异丁烯共沸物进行分离；④取消用于控制反应器温升的外循环回路。结果 ①将C₄原料中金属离子、碱性氮化物质量分数降至1 mg/kg以下,可保证催化剂长周期运行；②采用与C₄组分形成共沸的、来自水洗塔的溶解水和游离水作为催化蒸馏塔叠合反应的抑制剂,降低了TBA耗量及设备费用,简化了流程；③分别在高压塔、低压塔得到TBA质量分数≤100 mg/kg的叠合油、纯度大于99.99%的TBA；④在相同的条件下,降低了因反应产物返混造成的副反应产物生成量,使二异丁烯的选择性提高3%~7%、叠合反应器催化剂用量降低20%~40%。结论 装置经优化后可生产高纯度的二异丁烯产品,并可降低能耗。 

Abstract:

Objective Optimize the process flow of an industrialized isobutylene selective dimerization unit. Methods (1) Add water washing tower to remove metal cations and alkali nitrogen compounds from C₄ raw materials. (2) Remove the related pipelines and equipment used to directly inject TBA into the catalytic distillation tower. (3) Use a three-tower pressure-swing distillation process including "catalytic distillation tower + high pressure tower + low pressure tower" to separate TBA-diisobutylene azeotropes. (4) Remove the external circulating loops used to control the temperature rise of the reactors. Results (1) Reduced the mass fraction of metal ions and basic nitrides in C₄ to less than 1 mg/kg, which could ensure the long-term operation of the catalyst. (2) The dissolved water and free water from the water washing tower, which were azeotropic with C₄ components, were used as inhibitors for the dimerization reactions of catalytic distillation tower, which reduced the TBA consumption and equipment cost and simplified the process. (3) Dimers with TBA mass fraction equal or lesser than 100 mg/kg and TBA with purity greater than 99.99% could be obtained from high-pressure tower and low-pressure tower respectively. (4) Under the same conditions, the amount of side reaction products caused by the backmixing of reaction products was reduced, the selectivity of diisobutylene was increased by 3%-7%, and the amount of catalyst used in the reactors was reduced by 20%-40%. Conclusion After optimizations, the unit could produce high purity diisobutylene product and reduce energy consumption.