雾化角对造粒塔内颗粒飞行及换热影响的数值模拟

以某化工厂造粒塔为研究对象,通过对造粒塔中颗粒的运动进行受力分析,建立了颗粒运动速率方程,并结合单颗粒与气流间的Ranz和Marshall传热关联式建立了颗粒的对流换热模型。以此模型为基础,对颗粒的运动和温度变化进行了数值模拟,讨论了在不同颗粒直径下雾化角的取值及不同雾化角下颗粒温度的变化规律。一般来说造粒喷嘴的雾化角越大,对造粒越有利,但角度过大会出现碰壁的现象,造成产品形状不规则,降低产品的质量。考虑到实际运行状况,雾化角要尽可能地接近理论值,一般取小于理论值2°~3°即可。

The Numerical Simulation of the Effect of Atomizing Angle on the Particle's Movement and Convection in Granular Tower

Based on a granular tower in a chemical plant,through the force analysis of the particle movement and combining the heat transfer correlations of Ranz and Marshall between single particle and air current in granular tower,the velocity equation of the particle movement and the model of the particle convective heat transfer were established.The numerical simulation of the particle movement and temperature variation was made based on the model.The value of atomizing angle with different particle diameter and the temperature variation of particle at different atomizing angle were discussed.Generally,the larger atomizing angle,the better effect of spray granulation,but too big atomizing angle gives rise to the collision of particle against the wall of granular tower,the particle will be deformed and the product quality is dropped.Considering the actual condition in granular tower,the actual atomizing angle is less than the theoretic value by from two to three degrees.