Study On The Three Phase Circulating Fluidized Bed Evaporator During Concentrating Rhubarb Liquid Extract

In this paper, the vapor-liquid-solid three-phase circulating fluidized bed evaporator was applied to concentrate rhubarb liquid extract of Chinese traditional medicine considering its advantage. In the experiment, the force of inert particle was analyzed, and the flowing properties of the vapor-liquid-solid three-phase circulating fluidized bed evaporator were studied during concentrating rhubarb liquid extract of Chinese traditional medicine. The parameters such as evaporation temperature, difference in temperature of the fluid heating and heated, liquid flux, liquid thickness and the ratio of inert particles were changed to analyze and stndy this kind of equipments' heat transfer properties under different operational conditions. One model based on enhancement model was put forward. At the same time, based on the characteristics of three-phase circulating fluidized bed evaporator, another mathematical model of three-phase circulating fluidized bed evaporator heat transfer was proposed. The status of preventing and cleaning fouls such as fouling mechanism, preventing properties and mechanism were also studied during concentrating rhubarb liquid extract of Chinese traditional medicine.The results showed that the model' theoretical value that was calculated agreed well with the experimental data. The boiling heat transfer coefficient of the vapor-liquid-solid three-phase flow was about 1.4 times that of the vapor-liquid two-phase flow under the same conditions. On the other hand, the wall temperature was lower about 1.5 degree than that when the solid particles were absent. It was found that vapor-liquid-solid three-phase circulating fluidized bed evaporator with inert particles could enhance heat transfer, and prevent and clean fouls. Because vapor-liquid-solid three-phase circulating fluidized bed evaporator has good properties of heat transfer, preventing and cleaning fouls, it will be used broadly during concentrating the liquid extract of Chinese traditional medicine in the future.