The use of a composition including at least one acido-basic neutralising agent for decontaminating an atmosphere contaminated by a corrosive gas, the acido-basic neutralising agent having at least 2 pKa's and being characterised by: pKa 1≤pKa 2, pKa 1>2, pKa 2<12, 4<½ (pKa 1+pKa 2)<10 pKa 1, representing the smallest of the basic pKa's and pKa 2 representing the largest of the acidic pKa's. Also, a method for decontaminating an atmosphere contaminated by a corrosive gas comprising the spraying of the neutralising agent, and to a decontamination device.

A unit for recovering hydrogen chloride from an aqueous liquid which includes hydrogen chloride and is contaminated with compounds of low or no volatility, the unit having an evaporation unit for forming, from the liquid, a vapour which contains hydrogen chloride and a liquid concentrate which is contaminated with the compounds of low or no volatility, a first distillation unit for separating the hydrogen-chloride-containing vapour into a first top product and a first bottom product, and a second distillation unit for separating a hydrogen-chloride-containing aqueous fluid into a second top product and a second bottom product, one of these two distillation units being configured to be able to implement therein a distillation above the ambient pressure, and the other of these two distillation units being configured to be able to implement therein a distillation below the ambient pressure.

Systems and apparatuses for neutralizing acidic compounds in flue gases emitted from a heat recovery coke oven. A representative system includes a spray dry absorber having a barrel that includes a plurality of wall plates that form sidewalls of the barrel. The wall plates include a steel plate and a corrosion resistant alloy cladded to the steel plate and the wall plates are oriented such that the corrosion resistant alloy faces toward and is in fluid communication with an interior area of the barrel. The alloy is resistant to corrosion caused by the acidic compounds in the flue gas and can prevent the steel plate from being corroded by these acidic compounds.

An apparatus and method for treating a semiconductor process gas comprises a gas inlet allowing a treatment target gas (or gas to be treated) to flow therethrough; a catalytic reaction portion including a catalyst and configured to allow the treatment target gas to be brought into contact with the catalyst; a space velocity controller between the gas inlet and the catalytic reaction portion, the space velocity controller extending from the gas inlet in a diagonal direction in relation to the gas inlet; a differential pressure buffer portion between the space velocity controller and the catalytic reaction portion and including a filter; and a gas outlet configured to externally discharge a product formed as the treatment target gas comes into contact with the catalyst.

A process for purifying a feed gas stream containing at least 90% of CO.sub.2, at least 20% RH and at least one impurity chosen from chlorinated, sulfur-bearing, nitrated or fluorinated compounds is provided. The process includes a) subjecting the feed gas stream to catalytic oxidation producing a stream containing at least one of HCl, NOx, SOx or hydrofluoric acid; b) maintaining the temperature of the gas stream above the highest value between the dew points of water and the acid(s) contained in the gas; c) removing at least a part of the acid impurities by bringing the gas stream into contact with a corrosion-resistant heat exchanger to condense the acid compounds while regulating the temperature of the gas stream exiting below the dew point of water; and d) separating the acid condensates with a corrosion-resistant separator in such a way as to produce a CO.sub.2-enriched gas stream.

The invention relates to a method for reduction of HCl emission from a cement plant based on a treatment of a preheater (1) and/or bypass gas stream, characterized in that a cement raw meal, as a HCl absorber, is dispersed in the gas stream(s) from which HCl is to be removed; the cement raw meal is introduced from a raw mill (6) and/or a silo (8) into a pipe with a up going gas flow; the pipe being arranged in fluid communication at a point after a gas conditioning tower (7) and/or before a particle filter unit (5) and/or in a by-pass line before particle filter (4).

A method for producing aqueous hydrochloric acid from flue gases is provided. The method comprises conveying water to a first scrubber (102, 202, 302, 402, 502, 602, 702) or to a line (112b, 212b, 312b, 412b, 512b, 712b, 712c) to use the water in a scrubbing liquid of the first scrubber. The method also comprises providing flue gas containing chlorides into the first scrubber (102, 202, 302, 402, 502, 602, 702) and scrubbing the flue gas containing chlorides with the scrubbing liquid by contacting the flue gas with the scrubbing liquid in the first scrubber (102, 202, 302, 402, 502, 602, 702). Dilute hydrochloric acid and a flue gas derivate (104, 204, 304, 404, 504, 704) are produced. The method comprises letting out at least some of the dilute hydrochloric acid from the first scrubber (102, 202, 302, 402, 502, 602, 702) as a scrubber bleed, separating solids suspended by the scrubber bleed in a solids separator (192, 592, 692), conveying the scrubber bleed from the solids separator (192, 592, 692) into an evaporation vessel (194, 594, 694) and concentrating the scrubber bleed in the evaporation vessel (194, 594, 694) to produce hydrochloric acid vapor having a concentration of 5-22 wt-%. A corresponding system is also provided.

Systems and Methods to produce a lime hydrate sorbent composition formed of highly reactive lime hydrate (HRH) by adding compounds to the slaking water in a method that would produce a non-HRH, which will typically be a lime hydrate having citric acid reactivity as discussed above of more than ten seconds, to make the non-HRH an HRH, which is having a citric acid reactivity of less than or equal to ten seconds.

Provided is a process for separating an organic isocyanate prepared by reacting an organic amine with a stoichiometric excess of phosgene in the gas phase from the gaseous crude product obtained in the reaction, the process comprising the steps of (i) at least partially condensing the crude product stream containing at least the isocyanate, hydrogen chloride and unconverted phosgene by contacting with at least one liquid stream containing at least one quench liquid in a first separation apparatus to obtain a liquid stream containing at least some of the quench liquid and some of the isocyanate and a gas stream containing at least hydrogen chloride, evaporated quench liquid and phosgene, (ii) discharging the liquid stream obtained in step (i) via a first liquid outlet and of the gas stream obtained in (i) via a first gas conduit and (iii) at least partially condensing and/or absorbing the gas stream discharged in step (ii) through the first gas conduit, wherein that the at least partial condensation and/or absorption is effected in step (iii) by direct introduction of at least one cooling fluid, wherein the cooling fluid is introduced directly into the first gas conduit via at least one addition unit assigned to the first gas conduit.

Materials and methods for mitigating the effects of halide species contained in process streams are provided. A halide-containing process stream can be contacted with mitigation materials comprising active metal oxides and a non-acidic high surface area carrier combined with a solid, porous substrate. The halide species in the process stream can be reacted with the mitigation material to produce neutralized halide salts and a process stream that is essentially halide-free. The neutralized salts can be attracted and retained on the solid, porous substrate.