Typically, a gas enters the bottom of a scrubber and moves upward while a liquid is sprayed from the top. The soluble gas is carried away by the liquid exiting out the bottom of the unit. The most common application is flue gas desulfurization using ammonia as the solvent or spray liquid. The contaminated liquid exiting the scrubber represents it's own disposal problem. As this takes place, the acid in the gas neutralizes the alkali material and forms a fine white solid.
Gas flows through a rectangular duct containing rows of metallic strips.
The efficiency is a result of the precipitators applying the collecting force to the particles only and not the gas. Periodically, the precipitators have to be taken offline and cleaned. Refrigerated Vapor Condensation, Solvent Vapor Adsorption, and Flaring. The method chosen is dependent on allowable release concentrations and the value of the solvent. Due to the high cost of refrigeration, this option is usually reserved for expensive solvents whose recovery can justify the high operating costs.