The principle of Sodium chloride multi-effect evaporation crystallization
Sodium chloride multi-effect evaporation crystallization is a combination of multiple single-effect evaporators. Its characteristic is to use the waste steam generated by the front effect to heat the after effect evaporator, reducing energy consumption. There are usually double-effect evaporators, triple-effect evaporators and even multi-effect evaporators. The more control points, the greater the influence; the smaller the temperature difference driving force under different influences. The system should be selected according to the working conditions.
Sodium chloride multi-effect evaporation crystallization can be divided into ordinary multi-effect evaporation system and forced circulation multi-effect evaporator. Forced circulation multi-effect evaporator. The forced circulation multi-effect evaporator system designs multiple forced circulation pumps on the basis of multiple evaporators to increase the flow rate of the material in the evaporation tube, improve the heat transfer effect, and increase the evaporation intensity.
In Sodium chloride multi-effect evaporation crystallization, the steam generated by the first effect heated by live steam does not enter the condenser, but is reused as the second effect heating medium. This can effectively reduce the consumption of fresh steam by approximately 50%. Reusing this principle can further reduce the consumption of fresh steam. The highest heating temperature of the first effect and the lowest boiling temperature of the last effect form a total temperature difference, which is distributed in each effect. As a result, the temperature difference per effect decreases as the number of effects increases. Therefore, the heating area must be increased in order to achieve the specified evaporation rate. Preliminary estimates show that the effective heating area increases in proportion to the number of effects, so that while the amount of steam savings is gradually reduced, the investment cost is significantly increased.