Study On The Factors Of Influencing Moisture Content Of Milk Powder Gained By Air-blast Spray Drying

The structure of air-blast spray drying equipment is simple,the effect is good.So it is widely used in food drying process.In recent years the sale of milk powder has been steadily increasing,most of the milk powder production enterprises are using this way to process milk powder.So the study of air-blast drying technology is important to milk powder industry.Based on the spray drying experimental equipment provided by Tianjin University,this paper focused on the influence of some parameters on the moisture content of milk powder by theoretical analysis,experimental study and simulation.This can not only provide the basis for the production and processing of milk powder,but also can be used as the theoretical basis for the optimization of drying tower.Air-blast spray drying experiment platform was built and the effects of four single variables,such as inlet temperature、feed concentration、feed rate and air flow rate on the moisture content of milk powder were studied by experiment during the research.The experimental results were analyzed and the conclusions were drawn.The result of milk powder spray drying is determined by the moisture content of the dried milk powder particles.The mathematic model of air-blast spray drying was established during the research.In order to describe the spray drying process of milk powder,the gas phase governing equation,the particle motion equation,the gas-liquid two-phase mass transfer and heat transfer mathematical model and the gas-liquid coupling equation were established.This particle used the finite volume method to discretize gas phase control equation and particle motion equation,and used Simple algorithm to solve the gas phase control equations which are be discretized.This particle also used PSI-Cell algorithm coupling effect between gas phase and discrete phase calculation,use PSI-Cell algorithm to the coupling interaction between gas phase and discrete phase.ICEM-CFD software was used for building spray drying tower model and meshing this model.Fluent software was used for simulation calculation to the spray drying process in the drying tower.The temperature field cloud picture、the velocity field cloud picture、the humidity field cloud pictures of the air in the spray tower and particle trajectories picture and particle moisture content picture will be gained after calculation,and spray drying process can be analyzed by studying these pictures.The process plan of improving the drying effect of milk powder was obtained.The research process and conclusions can provide reference for the optimization of drying towers for processing milk powder.