Scrubber is a new type of gas purification equipment. It is produced based on the improvement of the gas purifier with floating packing layer. It is widely used in the pretreatment of industrial waste gas purification and dust removal, and the purification effect is very good. For coal gasification process, coal gas washing is inevitable. No matter what coal gasification technology, this unit operation is used. Because its working principle is similar to the washing process, it is named washing tower.

The washing tower is similar to the distillation tower, which is composed of tower body, tray, reboiler and condenser. As the scrubber is a device for coarse separation, the number of trays is generally small, and usually will not exceed ten levels. The scrubber is applicable to the separation of mixed gas containing a small amount of dust. Each component will not react, and the product should be easy to liquefy. Impurities such as dust (also known as high boiling matter) are not easy to liquefy or solidify. When the mixed gas flows into the scrubbing tower from the middle of the scrubbing tower, the product component liquid exists between the tower plates, and the product component gas vaporizes at the same time of liquefaction, while the impurities cannot be liquefied or solidified. When passing through the tray with liquid, they will be fixed by the product component liquid to produce scrubbing effect. The scrubbing tower is designed and manufactured according to this principle.

The scrubber is composed of tower body, tray, reboiler and condenser. During use, the reboiler is usually heated with steam, and the condenser is thermally conducted with circulating water. Balance shall be established before use, that is, pure product components shall be introduced, and their evaporation capacity and return flow shall be adjusted with steam and condensate, so that they can accumulate a certain thickness of liquid on the tray. When mixed gas components are introduced, they can quickly play the role of washing.

During use, it is necessary to control a liquid level, two temperatures and two pressure differences. That is, the liquid level of the washing tower, the gas inlet temperature, the tower top temperature, the pressure difference between the towers (the difference between the inlet pressure of the washing tower and the tower top pressure), and the condenser pressure difference (the difference between the tower top and the condenser outlet pressure). Generally speaking, the higher the gas inlet temperature is, the better. It can prevent impurities from solidification or liquefaction from entering the washing tower. However, it should not be too high to prevent the system from being difficult to control due to too high temperature. While controlling the temperature, it is also necessary to ensure the gas flow rate, that is, the inlet pressure should not be too small, so that the dust can enter the washing tower. After the mixed gas is introduced into the washing tower, part of the gas will condense into liquid and remain in the tower kettle. Adjust the temperature of the reboiler to make the liquid evaporate upward, and then adjust the condenser to make the liquid return to the tower plate to form a balance.

Since there is a certain thickness of liquid on the tray, there will be a certain pressure difference between the washing towers. When adjusting the reboiler and condenser, try to keep the pressure difference constant to form a balance. When adjusting the temperature at the top of the tower, it is necessary to prevent the impurities from vaporizing or sublimating into gas due to high temperature, but the condensation temperature should not be too low to prevent the product liquid from accumulating in the condenser and affecting the use. While paying attention to the above points, it is also necessary to use the reboiler to adjust the liquid level of the washing tower. In order to prevent the precipitation caused by the high concentration of impurities in the tower kettle liquid, it should be increased slowly.