Process, apparatus and plant for effluent-free absorption of gaseous substances and separation of heavy metal compounds from combustion gases, vapours and exhaust airs

摘要

A process for treating exhaust air, in particular for separating out sulphur and/or fluorine from exhaust air of the aluminium or ceramics industry, by absorption in at least one absorption chamber and a plant relating thereto are to be improved in that the exhaust air is conducted and deflected in a meander-like manner in an essentially horizontally-running flow path having a changing cross-section, the exhaust air passing through a spray mist from spray cones directed towards it, the spray mist being produced from scrubbing water having a nozzle admission pressure of 4.5 to 10 bar which is adjusted to pH 12 to 13 by NaOH or to pH 6 to 7 by Ca(OH)2. In the plant, a plurality of absorption chambers are provided next to each other and each two are connected together at their neighbouring ends to give a roughly U-shaped flow path in plan view. At least one of the absorption chambers has a cross-section tapering or expanding in the direction of flow and the subsequent absorption chamber has a cross-section expanding or tapering in the direction of flow, that is to say a cross-section changing in the opposite direction, at least one nozzle bar having spray mist-generating spray nozzles being provided in the cross-section of the absorption chamber.