Abstract: Gas contaminated with at least one noxious component, such as SO.sub.2, HF or NO.sub.x, is scrubbed with a clear, calcium-containing, initially-basic washing liquid which also comprises the anion of a strong inorganic acid, that of a polybasic carboxylic acid and, optionally, that of a monobasic carboxylic acid. Apparatus is provided for scrubbing the gas, oxidizing produced calcium bisulfite to calcium sulfate, separating out and removing solids, and recirculating clarified liquid for scrubbing contaminated gas.

Abstract: A process for the purification of gas, which is generated in pressure gasification of coal, which uses a wash oil, especially tar oil, as the washing liquid to avoid clogging of the washing apparatus by tars and tar compounds which precipitate out of the washing liquid when water or aqueous solutions are employed as the washing liquid. The wash oil is preferably used in the circulation, from which solids and tars are continuously removed, and is then fed into the pressure reactor again. The wash oil circulation is continually regenerated through distillation, and the residues are fed into the pressure reactor. Heat is constantly extracted from the gas before or during the washing in a heat exchange process, making it possible to keep the heat loss extremely low and to create optimum temperature at every point of the total cycle by appropriate extraction or addition of heat.

Abstract: The invention is concerned with improved process and apparatus for the removal of sulphur dioxide from flue gas or other waste gas of the kind in which the waste gas is scrubbed by a circulating wash liquid containing lime suspensions, i.e. suspensions of calcium oxide, hydroxide or carbonate, the calcium/sulphur compounds so formed being oxidized and removed from the circulation, the improvements of the present invention comprising primarily the freeing of the wash liquid from solid matter before contact with the waste gas and then the control of pH values of the wash liquid at different stages of the circulation to facilitate, for example, the oxidation of the particular calcium/sulphur compound, formed in the scrubbing process, to calcium sulphate, the apparatus also being designed to improve the oxidation step.

Abstract: This invention relates to the separation of droplets of a liquid (such as a washing liquid) from a gas, in which a stream of gas is conducted along a broad-fronted arcuate path, defined by interior and exterior walls, liquid droplets impinging upon the exterior wall and being directed through slits provided in said exterior wall. Flow of gas into, through and from the part-annular chamber defined by said walls is substantially in directions lying in planes, extending at right-angles to the longitudinal axis of the chamber with little or no movement in the longitudinal direction.

Abstract: Pulverulent solid sorption agent is injected into a stream of noxious-contaminant-containing gas subjected to intensive turbulence and then separated from the gas. The solid sorption agent is optionally reused until exhausted, or purified before reuse. Apparatus is provided for the process.