scrubber system

A dry or semi-dry scrubbing system, unlike the wet scrubber, does not saturate with moisture or the flue gas stream that is being treated. In some cases no moisture is added; while in other designs only the amount of moisture, which can be evaporated in the flue gas without condensing, is added. dry scrubbing system can be categorized as dry sorbent injectors (dsis) or as spray dryer absorbers (sdas). Spray dryer absorbers are also called semi-dry scrubbers or spray dryers. dry sorbent injection involves the addition of an alkaline material (usually hydrated lime or soda ash) into the gas stream to react with the acid gases. The sorbent can be injected directly into several different locations: the combustion process, the flue gas duct (ahead of the particulate control device), or an open reaction chamber (if one exists). The acid gases react with the alkaline sorbents to form solid salts that are removed in the particulate control device. These simple systems can achieve only limited acid gas (so2 and hcl) removal efficiencies. Higher collection efficiencies can be achieved by increasing the flue gas humidity (i.e., cooling using water spray). These devices have been used on medical waste incinerators and a few municipal waste combustors. in spray dryer absorbers, the flue gases are introduced into an absorbing tower (dryer) where the gases are contacted with finely atomized alkaline slurry. Acid gases are absorbed by the slurry mixture and react to form solid salts that are removed by the particulate control device. The heat of the flue gas is used to evaporate all the water droplets, leaving a non-saturated flue gas to exit the absorber tower. Spray dryers are capable of achieving high (80 + %) acid gas removal efficiencies. These devices have been used on industrial and utility boilers and municipal waste combustors. typical applications scrubbing fine particulates and acid gases emitted from incinerators, furnaces and boilersscrubbing gas phase particulate formations in electronics, chemical and heavy metals industriessulfur dioxide and hydrochloric acid removal