Working principle and function of washing tower

Washing tower is a new type of gas purification and treatment equipment. It is an improvement on the gas purifier with a floating packing layer and is widely used in pre-treatment of industrial waste gas purification, dust removal, and other aspects, with good purification effects. For Coal gasification process, gas washing is inevitable. No matter what Coal gasification technology, this Unit operation is used. Due to its working principle similar to the washing process, it is named the washing tower.

A washing tower is similar to a distillation tower, consisting of a tower body, a tray, a reboiler, and a condenser. Due to the fact that washing towers are equipment for coarse separation, the number of trays is generally small and usually does not exceed ten levels. The washing tower is suitable for separating mixed gases 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 substances) are not easy to liquefy or solidify. When the mixed gas flows into the scrubber from the middle of the scrubber, due to the product component liquid between the trays, the product component Liquefaction of gases will evaporate while liquefying, 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 washing effect. The scrubber is designed and manufactured according to this principle.

The washing tower consists of a tower body, a tray, a reboiler, and a condenser. During use, the reboiler is generally heated with steam, while the condenser is thermally conductive with circulating water. Before use, a balance should be established by introducing a relatively pure product component and adjusting its evaporation and reflux rate with steam and condensate water, so that it can accumulate a certain thickness of liquid on the tray. When the mixed gas component is introduced, it can quickly play a washing role. During use, it is necessary to control several key points such as a liquid level, two temperatures, and two pressure differentials. Namely, the liquid level of the scrubber, gas inlet temperature, tower top temperature, inter tower pressure difference (difference between scrubber inlet pressure and tower top pressure), condenser pressure difference (difference between tower top and condenser outlet pressure). Generally speaking, the higher the gas inlet temperature, the better it is to prevent impurities from solidifying or liquefying and not entering the washing tower. However, it should not be too high to prevent the system from being difficult to control due to high temperature. While controlling the temperature, it is also necessary to ensure the gas flow rate, that is, the inlet pressure cannot be too small, so that dust can enter the washing tower. After the mixed gas enters the washing tower, some of the gas will condense into a liquid and remain in the tower kettle. Adjust the temperature of the reboiler to evaporate the liquid upwards, and then adjust the condenser to reflux the liquid to the tower plate, forming a balance. Due to 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, it is necessary to maintain a constant pressure difference as much as possible to form a balance. When adjusting the top temperature of the tower, it is necessary to prevent impurities from vaporizing or sublimating into gas due to excessive temperature, which cannot serve as a washing agent. However, the condensation temperature should not be too low to prevent the product liquid from accumulating in the condenser and affecting its use. While paying attention to the above points, it is also necessary to use a reboiler to adjust the liquid level of the washing tower. To prevent excessive impurity concentration in the tower kettle liquid from causing sedimentation, it should be slowly raised.