With the rapid development of evaporation technology, evaporators are widely used in chemical, light industry, pharmaceutical, food and other industries. Evaporators are indispensable in the chemical industry, such as evaporation and concentration, evaporation and crystallization equipment, and with the development of chemical industry technology In order to cope with different wastewater, different industries, different materials, the types of evaporators are also more and more, the working principle and operation mode are slightly different. Let's take a quick look at the types of evaporators.
First, according to the retention of the solution in the evaporator: there are circulating evaporators and single-pass evaporators.
1. Circulating evaporator
In this type of evaporator, the solution circulates in the evaporator. The causes of the cycle are different, the operation is different, and it can be divided into two types: natural circulation and forced circulation. The natural circulation evaporator is further divided into a central circulation tube evaporator, a basket type evaporator, a column type evaporator, and a forced circulation type evaporator.
2, single pass evaporator
The main feature of this type of evaporator is that the solution passes through the heating chamber only once in the evaporator, and the concentrate is discharged without circulating. When the solution passes through the heating chamber, it flows in a film on the tube wall, and thus becomes a liquid film evaporator. According to different material flow directions, the single-pass evaporator is further divided into a rising film evaporator, a falling film evaporator, and a scraper evaporator.
Second, according to the evaporation method:
1. Natural evaporation: that is, the solution evaporates at a temperature lower than the boiling point, such as sea salt. In this case, since the solvent is vaporized only on the surface of the solution, the vaporization rate of the solvent is low.
2. Boiling evaporation: The solution is heated to the boiling point to evaporate under boiling conditions. Industrial evaporation operations are basically such.
3, according to the operating pressure of the evaporator
The evaporator can be divided into normal pressure, pressurized and reduced pressure (vacuum) evaporation operations according to the operating pressure. In general, heat sensitive materials such as antibiotic solutions, juices, etc. should be carried out under reduced pressure. High-viscosity materials should be heated by pressurized high-temperature heat source (such as heat transfer oil, molten salt, etc.).
4, according to the evaporator efficiency classification
Can be divided into single-effect and multi-effect evaporation. If the secondary vapor generated by evaporation is not directly utilized, it is called single-effect evaporation. If the secondary steam is used as the next heating steam and the plurality of evaporators are connected in series, the evaporation process is multi-effect evaporation.
5. Classification according to the evaporation process mode
According to the process mode of evaporation, it can be divided into batch evaporation and continuous evaporation. Intermittent evaporation refers to the evaporation operation of batch feed or discharge. The characteristic of intermittent operation is that the concentration and boiling point of the solution in the evaporator change with time throughout the process, so intermittent evaporation is an unsteady operation. Usually, intermittent evaporation is suitable for small-scale and multi-variety applications, and continuous evaporation is suitable for large-scale production processes.
Different types of evaporators, the environment used is also different, each has its own advantages. There are many types of evaporators. When choosing to use the evaporator, we should carry out the appropriate evaporator for the customer according to the condition of the materials on site, taking into account the structure and operation and maintenance of the evaporator.