If only classified from the purpose of the scraped film evaporator, it can be mainly divided into a forced circulation scraper type thin film evaporator and an ordinary scraper type thin film evaporator, wherein the forced circulation scraper type thin film evaporator is mainly On the basis of multiple evaporators, an extra pump for external circulation is added. Under normal circumstances, the double-effect evaporation system with heat pump is basically the same as the three-effect evaporation system in terms of energy consumption. It can evaporate the flow rate of the material in the entire tube and greatly improve the heat transfer effect. Increased the intensity of evaporation. Moreover, the forced circulation scraper type thin film evaporator can be used in the evaporation process, and crystallized or non-thermosensitive materials are present.

First, the heating area: Because the scraped film evaporator in the heated area, directly determines the material balance, heat balance and heat transfer calculations, as well as the selection of processes and forms, etc., are required to be comprehensively considered.

Second, the choice of the number of effects: the key to consider should be the size of the treatment, or the evaporation of the material at the boiling point of the elevated value, there is the number of equipment, if the processing capacity is relatively large, the best choice Multi-effect operation, because the more effect, the smaller the consumption of steam, and the higher the investment of the equipment; if the increase of the boiling point is relatively large, then the effective temperature difference will be smaller, the same adoption The number of effects should also decrease.