Developing and utilizing a mini food powder production facility to produce industrially relevant particles for functionality testing

In this thesis is presented research relating to a monodisperse droplet dryer for production of milk powder. The development and testing of several monodisperse droplet generators and lab-scale spray dryers was carried out. Furthermore, a number of down-scaled techniques for quality measurement were devised for analysis of the powder. Sufficient amounts of highly uniform powder could be dried to low moisture contents, using a range of feed solids concentrations and drying air temperatures. A single droplet drying model was created to simulate the situation, based on established mass and heat transfer equations and material specific kinetics using the Reaction Engineering Approach. Through a series of experiments varying drying temperature and feed solids content for a number of feed materials, the model was validated and its limits of accuracy were established. It successfully predicted the true final moisture contents and insolubilities in a range of conditions. The known and uniform temperature history and the regular particle sizes were then used to conduct original research on the formation of insoluble material during powder heat damage and the formation of particle morphology and shrinkage. Work was also done on spray freeze drying, thin layer drying, powder wetting, dissolution and the addition of surfactants.

本论文介绍了与用于奶粉生产的单分散液滴干燥器相关的研究。研究开展了多种单分散液滴发生器及实验室规模喷雾干燥机的开发与测试工作。此外，还设计了若干缩小规模的质量测量技术用于粉末分析。通过调整进料固体浓度范围与干燥空气温度，可干燥出足量且高度均一的粉末，使其达到低水分含量。基于已确立的传质传热方程及采用反应工程法（Reaction Engineering Approach）的材料特异性动力学，建立了单液滴干燥模型以模拟该过程。通过针对多种进料物料调整干燥温度与进料固体含量的一系列实验，对模型进行了验证并确定了其精度范围。该模型可在多种条件下成功预测真实的最终水分含量与不溶性。随后，利用已知且均一的温度历程与规则的颗粒尺寸，开展了关于粉末热损伤过程中不溶性物质形成及颗粒形态与收缩形成的原创研究。此外，还开展了喷雾冷冻干燥、薄层干燥、粉末润湿、溶解及表面活性剂添加相关的研究工作。