Exit Structure of the Mist Swirl Separators in Acrylonitrile Production Units
丙烯腈装置气液分离器的出口结构

The mist separator is a key apparatus in the acrylonitrile producing process, which is used to remove sulfuric acid mist from the gas product. High separation efficiency is necessitated to avoid the blockage and corrosion of the downstream facilities. The structure of the exit of the separator is one of the most important factors for increasing the separation efficiency. In the present investigation, 3-D gas flow field of the mist swirl separator was simulated using general CFD code PHOENICS. It was found that the separation efficiency of the mist separator could be improved by increasing the opportunity for liquid droplets to move towards the wall, as well as by decreasing the re-entrainment. The exit structure of mist swirl separator was then optimized experimentally according to the above CFD simulation findings. A new type of exit, double-deck sleeve, was developed and its structure was optimized. The experimental results showed that this structure had higher separation efficiency than other structures. High separation efficiency could be obtained at both low and high gas velocities, indicating better operating flexibility. The industrial application showed that the mist swirl separator with the optimized exit structure had higher separation efficiency than that of the original design.