非光气异氰酸酯热解反应釜流场和温度场的CFD模拟研究

Numerical simulation of the amplification of a non-phosgene isocyanate pyrolysis reactor

采用计算流体力学(CFD)方法研究了1 L、1000 L单层桨和1000 L双层桨非光气异氰酸酯热解反应釜的流场和温度场,同时研究了N 2吹扫对反应釜温度分布和温度变化速率的影响,结果表明:1 L、1000 L单层桨间歇热解反应釜流体经三叶搅拌桨加速后均分为上下两个循环区,上循环区平均温度高于下循环区平均温度;与1000 L单层桨热解反应釜相比,1000 L双层桨热解反应釜的双层桨之间形成了明显的漩涡,且不同搅拌时间下的温度变化情况与1000 L单层桨热解反应釜模拟结果基本一致,表明多层桨的引入对热解反应釜温度变化速率无明显影响;N 2通气速率从0增加到600 mL/min,反应釜内的温度变化速率由0.180℃/s增加到0.215℃/s,因此N 2的通入增加了热解反应釜内流体的湍动程度,增大了釜内侧的表面传热系数,导致温度变化速率增加。

The flow fields and temperature fields in 1 L,1000 L(single impeller),and 1000 L(double impeller)non-phosgene isocyanate pyrolysis reactor have been studied by the CFD method.The effect of N 2 purging on the temperature distribution and heat transfer rate in the reactors was also studied.The results showed that the flow fields in the 1 L and 1000 L(single impeller)batch pyrolysis reactor can be divided into upper and lower circulation areas by the three blade agitator,and the average temperature of the upper circulation area is higher than that of the lower circulation area.In contrast the 1000 L(single impeller)pyrolysis reactor,the 1000 L(double impeller)pyrolysis reactor has an obvious vortex between the double-layer impeller.The temperature changes after different stirring times are consistent with the simulation results for the 1000 L(single impeller)pyrolysis reactor.The introduction of multi-layer impellers has no obvious effect on the rate of temperature change in the pyrolysis reactor.When the flow rate of N 2 increased from 0 to 600 mL/min,the heat transfer rate in the reactor increased from 0.180℃/s to 0.215℃/s.This is because the introduction of N 2 increased the degree of turbulence of the fluid in the pyrolysis reactor,leading to an increase of the surface heat transfer coefficient as well as the rate of heat transfer inside the reactor.