Uniformity Of Liquid Film On Inert Particles By Spray Freezing Coating

Spray freeze drying technology(SFD)combines spray drying and freeze drying to Spray freeze drying technology(SFD)is a combination of spray drying and freeze-drying to form food,medicine and biological drying products which are more suitable for high added value.It is a technology that the droplets of atomized liquid are frozen to form powder particles at low temperature after atomization of liquid material and then dried to powder.The powder prepared by SFD has the advantages of uniform particle size distribution,good solubility and no damage to biological activity.It has become the key technology of preparing powder in biomedical industry.However,the existing spray freeze drying technology is not yet mature.In the production process,the problems of low output,continuous operation,poor mass transfer and heat transfer efficiency,and unstable product quality are the problems.In order to optimize SFD technology,Li Zhanyong proposed to add inert carrier particles to fluidized bed spray freeze-drying.The atomized material was then frozen on the surface of low temperature inert spherical carrier particles,then the carrier particles were freeze-dried after drying,and the powders were stripped after drying.Through this improved method,the spray freeze-drying process can be continuously operated without the need of two processing,so as to accelerate the drying process and realize the integration of equipment.In order to determine the design and experimental parameters of an inert particle spray freezing fluidized bed dryer,the experiment was carried out to study the freezing process of atomized droplet group on the surface of cryogenic carrier particles,and the experimental platform for coating droplet droplets on cryogenic carrier particles was built.A number of variables were used to observe the coating process of atomized droplets.The projection area and coating amount of droplets were obtained by high-definition camera photography and image processing tools.The effects of different factors on the coating of cryogenic carrier particles on droplets were analyzed.Using Minitab software,the main effect analysis and regression analysis of the data were carried out,and the multi-parameter mathematical equation of droplet group coated carrier particles was obtained.The variation trend of particle surface coating amount and coating thickness was predicted by the equation,which provided theoretical support for the controllability of coating process.The regression equation of coating projection area and coating quantity was obtained by experiment analysis.The reliability of the regression equation was higher than 99%.The critical state of particles when they were just fully coated was deduced.The minimum spray volume and coating thickness(140-180 um)required for coating carrier particles were obtained.The growth trend of carrier particle coating after fully coated was obtained.The spray volume of 3mm particles was 5.9%.The average coating thickness of 12 particles is 173.04 um,which is very close to the theoretical value of 173.71 um.It shows that the theoretical value is more accurate.It shows that the mathematical equation obtained in this study is more reliable and the theoretical value is very close to the actual value.It provides theoretical support for the dynamic process of particle surface coating and better realizes the detection of coating thickness and control.