Numerical Simulation Of Atomization Process And Flow Pattern Of Spray Drying Process

Spray drying,as a crucial operation for getting particle products in industrial production,converts solution to fine particle.It seems that the process of spray drying is quite simple,but the moving states and the mass or heat transfer procedures are very complicated.It requires a large amount of time and cost to obtain detailed data of spray drying through traditional experimental methods.Besides,some microscopic parameters cannot find in the experimental methods.Therefore,compared with the experimental method,computational fluid dynamics(CFD)modeling is a powerful and convenient tool for simulating the spray process.It is possible to obtain the actual moving status and the results of spray drying by numerical modeling,which can guide and predict the experimental research efficiently by numerical computation.In this work,the vital parts of spray drying were studied by CFD simulation comprehensively.The spray moiety directly affects the final particle morphology,size and distribution.Based on the verified CFD model,different materials of atomizer were simulated to investigate the effect on droplet size and distribution in this work.The modeling result proved that the droplet size and distribution were influenced by the resistance coefficient of materials,wherein the Reynolds number could change the effect of roughness along with the change of mass flow rate on spray process.The results in this work have implication for controlling droplet size through developing new spray nozzle with different materials or surface coating.In the drying process of atomized droplets,there are two different patterns for the drying air with different spray drying towers: direct flow and swirling flow.Different drying air flow patterns have significantly impact on the result of spray drying.Therefore,two models of different air flow patterns are built with same size for investigating the effect of air flow pattern on drying result.The simulation results show that the drying performance of the swirling drying tower is better than the direct flow drying tower,but problems also exist,like sticking walls and overheating.Besides,the special particle size distribution of drying polymer materials was discussed and some operation requirements were proposed to get qualified products.Spray drying of polymer materials should pay attention to control the temperature and residence time in drying tower for drying process.