The horizontal centrifugal thin film evaporator has the characteristics of low evaporation temperature, strong evaporation capacity, high evaporation efficiency and stepless speed regulation. This product is especially suitable for the concentration of heat-change substances (such as pigments, antibiotics, enzymes, etc.).
Since the main heating and evaporating parts of this product are conical jacket drums, the speed, viscosity and film thickness of each point are different when the material passes through the evaporation surface. Therefore, when calculating the heat transfer, it cannot be calculated by the conventional calculation formula. . We have summarized an empirical formula in practice, and now we will make an exploratory introduction.
1 conditions of use
2 Heat Transfer Calculation According to our experience, the following formula can be used as the heat transfer equation:
Q=KFA△tm..................................................................(2)
Where: Q--heat load, W;
K--total heat transfer coefficient, W/(m2·°C);
F--heat transfer area coefficient F=1+n/60;
N--drum speed, r/min;
A--total drum heat transfer area, m2;
Δtm - the average temperature difference between the two fluids undergoing heat exchange, °C.
2.1 Determination of the total heat transfer coefficient k The total heat transfer coefficient has a great relationship with the viscosity of the material, the concentration ratio of the feed liquid, the feed amount and other factors. The pigment liquid, the antibiotic liquid, and the food additive liquid are generally aqueous solutions. According to our test results, the total heat transfer coefficient is in the range of 1500 W/(m 2 · ° C) to 2000 w / (m 2 · ° C). When applied, the viscosity of the material is low, and the total heat transfer coefficient of the concentration ratio is high, and vice versa.
2.2 Determination of the average temperature difference Δtm
2.3 Determination of heat transfer area coefficient F Because the drum can be steplessly regulated, different speeds will also affect the heat transfer area. Therefore, the heat transfer area needs to be corrected. The heat transfer area factor F, F can be calculated by the following formula:
F=1+n/60............................................................(5)
Where: F--heat transfer area coefficient;
N--drum speed, r/min.
3 evaporation calculation
4 drum rotation speed determination
5 Conclusions Through the above discussion, the following conclusions can be drawn for the horizontal centrifugal thin film evaporator:
(1) The amount of solvent evaporation, which is related to the quality of the solvent (or solvent and water), the heat input, and the heat of vaporization of the solvent (or solvent and water);
(2) The rotation speed of the drum is related to the evaporation amount of the solvent, the heat of evaporation of the solvent, the evaporation area of the drum, and the average temperature difference between the two fluids for heat exchange, and the drum has a low rotation speed and a high rotation speed. limit.
July 20, 2022
