What are the applications and classifications of evaporators?

Evaporation is the physical process of transforming liquid into gas. Generally speaking, an evaporator is an object that converts liquid substances into gas. There are a large number of evaporators in industry, among which the evaporator used in refrigeration systems is one of them. The evaporator is an important component among the four major refrigeration parts. Low temperature condensed liquid passes through the evaporator, exchanges heat with the outside air, vaporizes and absorbs heat, achieving the cooling effect. The evaporator is mainly composed of two parts: the heating chamber and the evaporation chamber. The heating chamber provides the heat required for evaporation to the liquid, promoting boiling and vaporization of the liquid; The evaporation chamber completely separates the gas-liquid phase.

1. Classified by evaporation method:

Natural evaporation: refers to the evaporation of a solution at a temperature below its boiling point, such as seawater drying salt. In this case, the solvent only vaporizes on the surface of the solution, resulting in a low rate of solvent vaporization.

Boiling evaporation: Heat the solution to boiling point and evaporate it in a boiling state. The evaporation operation in industry is basically of this type.

2. Divided by heating method:

Direct heat source heating is the evaporation process of mixing fuel with air, causing the high-temperature flame and smoke generated by its combustion to be directly sprayed into the evaporated solution through a nozzle to heat the solution and vaporize the solvent.

The indirect heat source heats the walls between the containers and transfers it to the evaporated solution. The heat transfer process that occurs in a wall mounted heat exchanger.

3. Divided by operating pressure:

It can be divided into atmospheric pressure, pressurized, and depressurized (vacuum) evaporation operations. Obviously, for thermosensitive materials such as antibiotic solutions, fruit juices, etc., they should be processed under reduced pressure. And high viscosity materials should be heated by a pressurized high-temperature heat source (such as thermal oil, molten salt, etc.) for evaporation

4. Score based on effectiveness:

It can be divided into single effect and multi effect evaporation. If the secondary steam generated by evaporation is directly condensed and no longer utilized, it is called single effect evaporation. If secondary steam is used as the next heating steam and multiple evaporators are connected in series, this evaporation process is called multi effect evaporation.