Abstract: The process of phosgene-recirculation system in toluene diisocynate (TDI) production is analysed and two shortcomings of the old process are found：① High hydrogen chloride concentration of phosgene will decrease the reaction’s yield and ② The phosgene in the kettle under saturated state will become a potential hazard. In order to overcome these two shortcomings, a tower is added to purify the phosgene which is supercooled before entering the kettle to ensure safety. Compared with the old process, the weight percent of hydrogen chloride in phosgene decreases from 0.3% to 0.1%, a reduction of about 66.7%. Without any increase in refrigeration, the phosgene in the kettle is kept in a super-cooled state and production safety is improved.

摘要： 对甲苯二异氰酸酯（TDI）生产中光气循环系统流程进行了分析，认为原流程中存在两个缺点：①循环使用的光气中氯化氢含量过高，会降低反应收率；②光气罐中光气始终处于饱和状态，不利于安全。提出了增加光气提纯塔来降低循环使用的光气中氯化氢含量、在进入光气罐之前就冷却循环光气来增加光气罐安全性的改造方案。改造后，循环使用的光气中氯化氢的含量由原来的0.3%降低到0.1%，降幅达到66.7%；在冷量没有增加的条件下，使得光气罐中光气保持在过冷状态，提高了系统的安全性。