The following 3 points should be paid attention to when choosing a multi-effect evaporator for sodium chloride in vacuum concentration equipment:

The following 3 points should be paid attention to when choosing a multi-effect evaporator for sodium chloride in vacuum concentration equipment:

1. Efficiency number: mainly consider the size of the processing capacity, the boiling point rise value of the evaporated material, and the number of equipment.

2. Process: In the downstream process, the pressure of the after-effect evaporation chamber is lower than that of the former effect, and the pump power required for the transportation of the solution between the effects is small. In addition, because the after-effect evaporation temperature is low, part of the steam will be flashed out after the fore-effect solution enters the after-effect, so the consumption of raw steam is relatively small. In the downstream process, the concentration of the after-effect is high, the temperature is low, the viscosity is increased, and the heat transfer rate is small.

3. Heating area: The heating area of the evaporator is determined after comprehensive consideration of factors such as material balance, heat balance, heat transfer calculation and the adopted process form.

According to the number of effects, it can be divided into single-effect and multi-effect evaporation. If the secondary steam generated by evaporation is directly condensed and no longer used, it is called single-effect evaporation. If the secondary steam is used as the next effect heating steam, and multiple evaporators are connected in series, this evaporation process is called multi-effect evaporation. According to the situation that the solution stays in the evaporator, it can be roughly divided into two categories: circulation type and single-pass type.

According to the operating pressure, it can be divided into normal pressure, pressurized and reduced pressure (vacuum) evaporation operations. Obviously, for heat-sensitive materials, such as antibiotic solutions, fruit juices, etc., it should be carried out under reduced pressure. High-viscosity materials should be heated by a pressurized high-temperature heat source (such as heat transfer oil, molten salt, etc.) for evaporation.