高黏度聚合MDI新工艺的设计及运行优化

Design and optimization of novel process for high viscosity polymeric MDI

简述了目前生产高黏度聚合MDI(多亚甲基多苯基多异氰酸酯)的3种生产工艺,为解决现有工艺中存在的填料污染、纯MDI质量差等问题,文中结合现有工艺的特点设计了短程蒸发+分离塔组合新工艺,对新工艺进行了物料平衡模拟以及短程蒸发器关键参数计算,并将短程蒸发+分离塔新工艺进行了工业化实施。为实现新工艺的长周期稳定运行,开展了短程蒸发+分离塔新工艺下的刮片材质优化、防飞溅挡板优化、操作温度优化等。通过设备及工艺条件优化,短程蒸发+分离塔新工艺工业化装置实现6个月以上的长周期运转,同时中间体M中重组分质量分数、PM中二聚体质量分数都较现有工艺大大降低,新工艺生产的高黏度聚合MDI的低温稳定性、长期储存稳定性均优于分离塔工艺,高黏度聚合MDI产品质量明显提升。文中通过工艺流程设计、模拟计算、工业化实施、装置运行优化等,将短程蒸发+分离塔新工艺成功地用于生产高黏度聚合MDI。

Three present processes of producing high viscosity polymeric MDI were summarized. In order to solve the problem of filter pollution and poor quality of high viscosity polymeric MDI, a new process was successfully designed which combined knockout tower with short-path distillation. During the industrial application of this process, the materials balance was simulated and the critical parameters of the short-path distillation were calculated. With the optimization of the evaporation temperature of short-path distillation procedure, the material of scrapers and anti-spatter baffles, the short-path distillation ＆ knockout tower process was proved to be capable of stable operation for more than six months. Compared with the former three processes, the heavier components contained in M and the dimers contained in PM-700 significantly decreased. Products through this new process presented a better stability under low temperature and a longer shelf life, which showed a huge raise in quality. In conclusion , design the short-path distillation ＆ knockout tower process and managed to produce first class high viscosity polymeric MDI through process design, analog calculation, industrialized application and operation optimization.