Quality Evaluation Of Pumpkin Juice During The Concentrating Process And Study On Evaporation Characteristic Of The Three-Phase Circulating Fluidized Bed Evaporator

In this paper, we applied the vapor-liquid-solid three-phase circulating fluidized bed evaporator to condense pumpkin juice. We evaluated the quality of pumpkin juice during its concentration process, and studied the synthetic characteristics of this equipment. We studied the carotene loss with the change of temperature and solid content of pumpkin juice during the thermal process. We obtained the kinetics model of carotene loss during this process, and then based on the former we established the kinetics model during the concentration process and the quality evaluation criterion. We studied the characteristics of concentrating and protecting quality comparing with vapor-liquid two-phase evaporator. We changed the parameters such as evaporating temperature, temperature of vapor, liquid flux, liquid thickness and the ratio of inert particles to analyze and study the heat transfer properties of three-phase circulating fluidized bed evaporator in different operational conditions. The heat transfer model was put forward and the experimental value accorded with the theoretic value calculated well. At the same time, we also studied the flow status and the characteristic of preventing and cleaning fouls.The results showed that the vapor-liquid-solid three-phase circulating fluidized bed evaporator had good characteristic of heat transfer, and its heat transfer coefficient was 1.35 times of the vapor-liquid two-phase evaporator's. Carotene loss in three-phase circulating fluidized bed evaporator was less than in two-phase evaporator. Inert particles could prevent and clean the fouls. The vapor-liquid-solid three-phase circulating fluidized bed evaporator has good synthetic performance, and it will be used broadly in foodstuff field in the future.