Integrated and intelligently controlled unit for suspension freeze concentration: design and experimental verification

Suspension freeze concentration (SFC) can avoid denaturation while concentrating thermal-sensitive aqueous solutions. However, the complex treatment process and high capital cost severely limit its application in large-scale production. In this paper, a compact and integrated unit is devised to overcome these shortcomings and improve the operability of SFC. The unit is in a vertical layout and supports multistage treatment to successively condense the solution. Several innovative designs are made for the key components, including the helical blades in the scraped surface heat exchanger and a dual-use column for recrystallization and washing. The former helps to establish the circulation of solution and impose forces to compress the ice column, while the latter enables seamless switch between different processes. As the whole process of SFC is well known to be time-consuming and labor-intensive, an intelligent controlling system is installed on the unit to realize on-site and/or remote monitoring and adjustment of the treatment. A concentration experiment using apple juice was conducted to verify the design and demonstrate the advantages. The results show that high-quality solutions were obtained with this unit. The recovery yields of the soluble solids and nutrients components are over 98.5% and 80.0%, respectively. Based on the work principles of the freezing and washing process in this design, the mechanism behind the superior recovery yields is analyzed. This study opens up a potential route for scaling up SFC and is expected to stimulate further work to achieve industrial application.

悬浮液冷冻浓缩（Suspension freeze concentration，SFC）可在浓缩热敏水溶液的同时避免物料变性。然而，其处理流程复杂、初始投资成本高昂，严重制约了该技术在大规模生产中的应用。本文设计了一款紧凑集成化装置，以克服上述缺陷并提升悬浮液冷冻浓缩的操作性能。该装置采用立式布局，支持多级处理以实现溶液的连续浓缩。关键组件采用多项创新设计，包括刮板式换热器内的螺旋叶片，以及用于重结晶与洗涤的两用柱体。前者可促进溶液循环并施加作用力以压缩冰柱，后者则可实现不同工艺间的无缝切换。鉴于悬浮液冷冻浓缩全流程普遍存在耗时耗力的问题，该装置搭载了智能控制系统，可实现处理过程的现场及/或远程监测与调控。本研究以苹果汁为原料开展浓缩实验，以验证该装置设计的合理性并展示其优势。实验结果表明，该装置可制备出高品质的浓缩液，其中可溶性固形物与营养成分的回收率分别可达98.5%与80.0%以上。本研究基于该设计中冷冻与洗涤工艺的工作原理，分析了其高回收率背后的机制。本研究为悬浮液冷冻浓缩技术的规模化应用开辟了可行路径，有望推动相关研究进一步实现其工业落地。