关键词: 异氰酸酯, 光气回收, 优化设计, 模拟优化

Abstract: The traditional method of phosgene recovery for 3-chloro-4-methyl phenyl isocyanate (CMPI) equipments has following disadvantages：The phosgene cannot be recovered completely. Once the phosgene goes to the off-gas，there would be some bad consequence such as：the security of system is decrease；the security of system，the cost of production，the consumption of sodium hydroxide and the discharge of waste water are increase. The research in references which studied the phosgene recovery for producing toluene diisocyanate cannot be used in CMPI system for the difference of reactive conditions. An equipment of 2000 t/a for producing CMPI was taken for example，the phosgene recovery system was simulated and optimally designed：Under the condition of meeting the technological requirements，the number of theoretical plates was identified as 12 and the optimal feeding rate was defined as 780 kg/h. We as compared the phosgene recovery systems of normal pressure reactive system and that of high pressure. The results showed that under normal pressure system，the phosgene recovery system needed more absorbent than that of under high pressure，but no intercooler in the absorber was needed and the theoretical explanation for the phenomenon was provided. Considered the generility for various kinds of isocyanate production processes，the conclusion of this study can be applied in other similar isocyanate equipments.

Key words: isocyanate, phosgene recovery, optimal design, simulation and optimization