二苯基甲烷二异氰酸酯精馏过程节能工艺研究

为了开发二苯基甲烷二异氰酸酯(MDI)分离的节能流程,采用热平衡法和有效能分析法,对MDI精馏过程进行节能研究,从单个换热过程到整个系统分3个步骤进行改进。首先改变脱光气塔和减压脱溶剂塔的用能品位,节省高品位热源;然后通过回收各个子系统的冷凝热和冷却热,实现单元内部的能量再利用;最后通过常压脱溶剂塔与脱光气塔的热量集成,使得能耗进一步降低。通过以上3个过程的节能改进,得到的工艺流程同原工艺相比节能30%以上。给出的节能方法适用于MDI分离过程,也可应用于类似的宽沸程物系的分离过程。

Study of energy saving of MDI distillation process

In order to develop energy saving technology for MDI separation process,both heat equilibrium and exergy analysis methods were used to study the process.From single unit to whole system,the solving procedure included three steps: firstly,the heat sources of dephosgenizing and desolventization columns were changed to save the heat source with high temperature;secondly,the heat of condensation and cooling of some operation units was reused;finally,thermal coupling was realized between dephosgenizing column and desolventization column.After the procedure provided was carried out,the energy consumption of the MDI separation process reduced by 30% above.The result shows that the energy saving method is suited for the MDI separation process and can be applied to other similar wide-boiling systems.