Abstract: An improved sulfur-ammonia process for removing hydrogen sulfide from coke oven gases. In the improved process, a concentrator formerly used for standby operation is used at all normal times as an ammonia scrubber to improve the efficiency of gas separation during normal operation and is used as a concentrator for its intended standby functions during the alternative operations. In its normal function, the concentrator/scrubber functions as a scrubber to strip ammonia gas from recirculating liquid streams and to permit introduction of an ammonia-rich gas into a hydrogen sulfide scrubber to increase the separation efficiency of that unit. In the standby operation, the same concentrator/scrubber serves as a concentrator to concentrate hydrogen sulfide in a "strong liquor" stream for separate recovery as a "strong liquor.

Abstract: Hydrogen cyanide in hydrogen cyanide containing gas is transformed into ammonia by a special iridium catalyst in the presence of at least the equivalent amount of hydrogen for the change. The ammonia is analyzed to provide a measure of the hydrogen cyanide in the hydrogen cyanide containing gas.

Abstract: Ion exchange techniques are utilized to treat waste water flows, especially those from plating baths, by passing the waste water through a multi-level ion exchange resin bed, the bed thereafter being regenerated by a series of steps, including backwashing, passage of an acidic regeneration fluid through the bed, multi-stage rinsing of the bed, and passage of a caustic regeneration fluid through at least a portion of the bed. Acidic waste flows developed during regeneration steps are, when desired, further treated to recover cyanide values therefrom by heating same within a generally closed tank to drive off a hydrocyanic gas, which is then reacted with caustic within a circulation reactor having an inclined passageway in order to form and recover a cyanide salt liquor suitable for re-use in the plating bath.

Abstract: A process is disclosed for the purification of an inert or non-reacting gas such as lower mono-olefins by the removal of trace amounts of reacting impurities such as carbon dioxide therefrom, comprising passing said gas through an essentially non-aqueous liquid solution of alkali or alkaline earth metal hydroxides and/or weak acid salts and certain selected liquid polyhydric alcohols.

Abstract: A cyclic urea reaction product forms as a by-product of a hindered amine acid gas scrubbing process and results in an ultimate buildup of the material in the circulating amine scrubbing solution. The buildup of this material has a deleterious effect on acid gas removal rates and accordingly, results in inefficient acid gas removal. In the process of the present invention, the cyclic urea degradation product is removed from the circulating solution by employing a selective precipitation of the cyclic urea followed by filtration. The selective precipitation is carried out by cooling the circulating solution to a particular temperature level such that the cyclic urea comes out of solution while the other components remain in solution.

Abstract: This invention relates to a process for reducing the hydrogen cyanide content of a gaseous stream which comprises providing an adsorbent bed wherein the adsorbent comprises zinc oxide and contains no more than 5%, by weight, of an oxide of an alkali or alkaline earth metal, and contacting said process stream with said adsorbent bed at a temperature of from about ambient to about 350.degree. C. for a period of time sufficient to reduce the concentration of hydrogen cyanide in said gaseous stream to the desired value.

Abstract: Inert gas-permeable granular support materials impregnated with alkali ferrates wherein the ferrates are iron compounds having an oxidation state of +4, +5, or +6 are disclosed. When they are used as a granular filter material in combination with a tobacco product, hydrogen cyanide can be significantly reduced in the smoke obtained from the tobacco product. Activated carbon or alumina impregnated with sodium permanganate and a basic sodium compound may also be combined with the granular filter material.

Abstract: A method is provided for the treatment of a waste water stream characterized by having toxic and corrosive properties due to the presence of a cyanides formates and a halide of a metal or ammonia comprising adding a ferrous ion to said waste water to convert the cyanides to iron cyanides, adding a base to said waste water until the pH of said waste water is adjusted to the range from about 9 to 11 to precipitate a sludge containing said iron cyanides, feeding said waste water to a biological reactor to convert said formates to carbon dioxide and a biological residue and recovering an environmentally upgraded waste water stream from said biological reactor.

Abstract: Organic refuse is pyrolyzed to form disposable solids and gas. The gas is washed at a temperature well above 100.degree. C. with wash oil, which is recirculated. Spent wash oil is pyrolyzed with contaminants and further organic refuse. The washed gas is filtered through sorption means to remove acid and or other noxious gases therefrom before being cooled well below 100.degree. C. to condense water vapor and other constituents having boiling points within the range of from, e.g., 75.degree. to 150.degree. C. After separating the resulting condensate, thus-purified combustion gas is used, e.g., as a fuel source for the organic-refuse pyrolysis.

Abstract: Pulverent solid sorption agent is injected into and, optionally, admixed with a stream of noxious-contaminant-containing gas and then separated from such gas. The solid sorption agent comprises an alkali-metal and/or alkaline-earth-metal compound and advantageously contains iron-III-oxide; such agent is preferably in the form of dust developed during production of iron or steel.

Abstract: A process for purifying gases containing hydrogen sulfide and/or hydrogen cyanide is provided wherein said gases are contacted with an absorbing solution containing naphthols or their salts as a catalyst having a nitroso group at .alpha.-position or .beta.-position and also acidic group(s) and also having a standard redox potential in the range of 0.4 V or higher but lower than 0.7 V to remove hydrogen sulfide and/or hydrogen cyanide by converting the former mainly into thiosulfuric acid and the latter mainly into thiocyanic acid. According to this process, no trouble caused by sulfur deposit as seen in conventional method occurs, and the scale of purification apparatus is made smaller, and also the amount of catalyst required for purification is reduced. Further, by pretreating the absorbing solution, this process becomes more advantageous.

Abstract: Clean HCN-free synthesis gas is produced from raw synthesis gas leaving a partial-oxidation gas generator by a continuous process comprising the steps of partial cooling, scrubbing with condensate, cooling below the dew point by indirect heat exchange preferably with a rich liquid absorbent from a downstream acid-gas-removal zone, and scrubbing with cold aqueous absorbent. The rich HCN-containing aqueous absorbent is then safely processed, without polluting the environment. For example, the HCN-containing aqueous absorbent may be stripped or reacted in the gas generator. Optionally, other acid gases, if present, may be removed from the synthesis gas in said acid-gas-removal zone.

Abstract: A cyclic urea reaction product forms as a by-product of a hindered amine acid gas scrubbing process and results in an ultimate buildup of the material in the circulating amine scrubbing solution. The buildup of this material has a deleterious effect on acid gas removal rates and accordingly, results in inefficient acid gas removal. In the process of the present invention, the cyclic urea degradation product is removed from the circulating solution by employing a selective precipitation of the cyclic urea followed by filtration. The selective precipitation is carried out by cooling the circulating solution to a particular temperature level such that the cyclic urea comes out of solution while the other components remain in solution.

Abstract: Optimum concentration of the acid-scrubbing solution employed in a scrubbing tower for removal of malodorous and/or toxic gases from the air is maintained automatically in a control system which senses the electrical conductivity of the solution to control acid-feeding apparatus. High and low concentration alarms are also provided to warn of malfunction.

Abstract: A process for the removal of hydrogen cyanide and of metals which form carbonyls from gases produced by partial oxidation of hydrocarbons with steam and oxygen is described involving use of an alkaline solution containing a carbonyl inhibitor in the scrubber.

Abstract: Hydrogen cyanide, carbon dioxide and ammonia present in a nitrile production effluent are recovered as an aqueous solution containing ammonium carbonate and ammonium cyanide. The cyanide is hydrolyzed to ammonia and carbon monoxide, followed by recovery of carbon monoxide, carbon dioxide and ammonia, all free of cyanide, from the hydrolyzed solution. In this manner, ammonium values are recovered from the cyanide byproduct and recovered streams are free of cyanide.

Abstract: Process for removing gaseous impurities such as CO.sub.2, H.sub.2 S, HCN and SO.sub.2 from a gaseous mixture containing the same, comprising an absorption step in which the gaseous impurities are removed by a scrubbing solution, and a regeneration step in which the exhausted solution is submitted to stripping to remove the inpurities. The regenerated solution is treated with a flow of inert gases to improve the degree of regeneration and extract heat from said solution. The flow of inert gases, containing steam and desorbed impurities, is further enriched in steam supplied from the exterior and the resulting mixture is used as stripping means in the regeneration step.

Abstract: Carbon dioxide containing acidic gases are removed from a normally gaseous mixture by a process comprising contacting the normally gaseous mixture with an aqueous solution comprising (a) a basic alkali metal salt or hydroxide and (b) an activator for said basic salt or alkali metal salt or hydroxide comprising at least one sterically hindered amine.

Abstract: Carbon dioxide containing acidic gases are substantially removed from a normally gaseous mixture by a process comprising contacting the normally gaseous mixture with an aqueous amine solution, wherein at least one of the amines is a sterically hindered amine. The process is operated at a thermodynamic cyclic capacity (as determined from the vapor liquid equilibrium isotherm of the vapor-liquid system) which is greater than in an aqueous amine CO.sub.2 scrubbing process wherein monoethanolamine is the only amine utilized under similar conditions of gaseous feed composition, scrubbing solution composition, temperatures and pressures. A particularly preferred sterically hindered amine is 2-amino-2-methyl-1-propanol.

Abstract: A process for the separation of carbon monoxide from mixed gases comprising contacting the mixed gases with an absorbent system consisting essentially of an inert diluent and a copper (I) salt of a sulfonic acid or of a dialkyl phosphate.

Abstract: Thiosulphate ions present in gas purification liquors, particularly those employed for removing H.sub.2 S by washing with aqueous alkaline solutions of vanadium compounds and anthraquinone disulphonic acids, are decomposed to sulphide and hydroxyl ions by exposing the liquor to a hydrogen rich gas at elevated temperature e.g., 650.degree. C. The liquor may be evaporated and the solid residue subjected to decomposition. Any thiocyanate ions are hydrolyzed; it being necessary to mix steam with the hydrogen rich gas if a solid residue is being decomposed.

Abstract: A process for purifying gases produced by the gasification of fossil fuels by a treatment with water vapor and oxygen under superatmospheric pressure. The raw gas produced is treated to remove catalyst-deteriorating impurities such as mono- and polyunsaturated hydrocarbons, mercaptans, HCN, HCl, H.sub.2 S, CS.sub.2, COS, and NH.sub.3, and to desulfurize the gas to produce an exhaust gas which is rich in H.sub.2 S. The gas is cooled and scrubbed under superatmospheric pressures and at normal temperatures. The raw gas, at a temperature of 150.degree.-170.degree. C., is indirectly cooled to ambient temperature. The condensible hydrocarbons are then separated and removed, and the gas is then scrubbed with water to remove ammonia in a first scrubbing stage wherein the rate of water addition is controlled to be just sufficient to remove the ammonia.

Abstract: An exhaust gas containing nitrogen oxides is efficiently purified without the necessary use of catalysts by contacting the exhaust gas with a nitrile compound at high temperature in the presence of oxygen, whereby the nitrogen oxides and the nitrile compound are selectively decomposed into harmless materials.

Abstract: A process is provided for removing ammonia, hydrogen sulfide and hydrocyanic acid from gases such as coke oven gas. In carrying out the process, the gas to be cleaned is first washed with an alkaline solution to remove the hydrogen sulfide and hydrocyanic acid. The hydrogen sulfide is oxidized by air to produce elemental sulfur, which is removed, and the alkaline solution is recirculated for reuse, a portion of the solution carrying cyanide and other compounds being diverted for further treatment. The gas to be cleaned is subjected to a second washing operation with an inorganic acid solution which removes the ammonia from the gas by formation of an ammonia salt solution. The salt solution is regenerated to recover the acid which is recirculated for reuse.

Abstract: Improvements in the elimination and recovery of gaseous acid impurities from a gaseous mixture containing them, by an absorbing step, wherein said gaseous mixture is brought into contact with an alkaline absorbing solution and a regeneration step wherein the exhausted absorbing solution is regenerated by steam stripping, said absorption step comprising a main column and a secondary column, the main column operating at a higher pressure and by means of a supply of outside heat, the secondary column operating at a lower pressure and substantially by means of the steam obtained by expansion of the solution regenerated in the main column. The exhausted solution to be regenerated is conveyed firstly in one of the two regeneration columns wherein it is regenerated in an incomplete way, and subsequently into the other column where its regeneration is completed.

Abstract: In purifying a gas containing at least one of hydrogen cyanide and hydrogen sulfide as a harmful component by fixing the harmful component in water as an aqueous solution of nitrogen-containing sulfur compound so as to render the gas free of the harmful component, an improvement characterized by:1. burning the aqueous solution of nitrogen-containing sulfur compound to obtain an exhaust gas containing sulfur dioxide,2. separating the sulfur dioxide from the exhaust gas for recovery, and3. exhausting the gas after the separation of the sulfur dioxide.

Abstract: A process for the recovery of pure concentrated ammonia in which the gaseous products of coal gasification or degassing are condensed or are washed with water to produce a phenolic-containing liquid phase (gas water), this liquid is dephenolated by extraction with a solvent, the phenol is recovered from the solvent and the gas is driven from the liquid phase. The gas is washed with circulated phenol and residual solvent is eliminated therefrom after NH.sub.3 is removed by washing.

Abstract: A process for treating a hydrogen sulfide-containing feed gas, deficient in thiocyanate ion precursors, to convert the hydrogen sulfide to elemental sulfur in which said gas is contacted with an aqueous alkaline washing solution containing a water-soluble metal vanadate, and a water-soluble anthraquinone disulfonate to yield an effluent gas of reduced sulfur content. Thiocyanate ion precursors are added to the solution to reduce the chemical consumption of the anthraquinone disulfonate. The solution is thereafter regenerated by contact with an oxygen-containing gas; elemental sulfur is recovered from the solution; and the regenerated solution is recycled to the gas-contacting step.

Abstract: In the process disclosed, gas from a coke plant is washed with an aqueous metallic salt solution including sulfureous and sulfuric acid to absorb the ammonia, hydrogen sulfide and hydrogen cyanide from the gas. The washing solution is then oxidized in an aerating tank to recover elementary sulfur. A portion of the washing fluid from the oxidizer is returned for continued washing of gas and a portion of the fluid is heated in the presence of a catalyst to yield products of combustion including an acid anhydride and a metal or metal oxide. After processing the combustion products through a heat recovering system, the acid anhydride and metal oxides are combined and react to form renewed aqueous metal salt solution that is combined with the oxidized washing solution to wash additional quantities of gas.

Abstract: A method of removing tetranitromethane from waste gases (e.g., from trinitrotoluene plants) by scrubbing the waste gases with a mixture of 1 an alkali metal hydroxide, 2 water, and 3 a liquid alcohol. Most of the tetranitromethane is converted into a soluble alkali metal salt of trinitromethane.

Abstract: A method of removing tetranitromethane from waste gases (e.g., from trinitrotoluene plants) by scrubbing the waste gases with a solution of (1) water, (2) hydrogen peroxide, and (3) an alkali metal hydroxide or alkali metal carbonate. Tetranitromethane is converted into trinitromethane or a soluble alkali metal salt of trinitromethane.

Abstract: A continuous process is provided which has the primary purpose of removing NH.sub.3, H.sub.2 S, HCN, and (CN).sub.2 from the subject gas mixtures and the secondary purpose of producing (NH.sub.4).sub.2 SO.sub.4 and iron oxide for industrial uses. The gas mixture which contains tar and other condensible vapors, NH.sub.3, H.sub.2 S, HCN, and (CN).sub.2 together with small volumes of gas from the ammonia still of the system, and gas from a system H.sub.2 SO.sub.4 plant, is contacted in a single three-stage reaction chamber in the presence, if need be, of a tar solvent, additional NH.sub.3, and the reagent Fe(OH).sub.2, which itself is a product of a concurrent reaction between NH.sub.3 and FeSO.sub.4. The unpurified gas mixture's condensible vapors are largely prevented from condensing by maintaining a steady, elevated temperature, while the mixture is essentially freed of HCN, (CN).sub.2, NH.sub.3, and H.sub.2 S in the reactor before the gas mixture passes through a primary gas cooler.

Abstract: A method for removing efficiently and economically harmful materials from a waste gas exhausted in a process for producing acrylonitrile by ammoxidation of propylene, which comprises dividing the waste gas exhausted after the absorption of acrylonitrile into two flows, mixing the first flow gas with air in an amount necessary for combustion of the combustible gas contained in the whole waste gas, subjecting the main flow gas of the mixed gas thus obtained to heat-exchange with the gas of the outlet of the first catalyst layer, combining the main flow gas with the remainder of the mixed gas, preheating thereby the mixed gas at a temperature of 200.degree. to 450.degree. C, passing the preheated mixed gas through the first catalyst layer wherein at least one noble metal is dispersed on an alumina carrier, and therein burning the gas at a temperature of 650.degree. to 750.degree.

Abstract: SO.sub.2 is removed from a SO.sub.2 -containing gas mixture utilizing an aromatic amine as absorbent, followed by scrubbing the SO.sub.2 -depleted, aromatic amine-enriched effluent gas with sulfurous acid-and ammonium sulfate-containing aqueous solution to remove substantially all of the gaseous aromatic amine from the gas. The effluent gas is discharged ultimately to the atmosphere without any additional scrubbing of the gas, after its discharge from the sulfurous acid scrubbing zone, with sulfuric acid solution or any other acid solution or any acid.

Abstract: Ammonia is added to combined aqueous scrubbing solutions containing an organic base-sulfuric acid reaction product, preferably an aromatic amine-sulfuric acid reaction product, an organic base-sulfurous acid reaction product, preferably an aromatic amine-sulfurous acid reaction product, and water in one or more separating zones located exteriorly of an absorption tower. The combined aqueous scrubbing solutions are obtained from sulfurous acid and sulfuric acid solution scrubbing sections of the absorption tower wherein an organic base, preferably an aromatic amine, is utilized as absorbent in a lower absorber section of the tower to remove SO.sub.2 from a SO.sub.2 -containing gas mixture, followed by scrubbing the SO.sub.

Abstract: An improved process for recovery of hydrogen cyanide contained in a gaseous mixture is provided which comprises (a) contacting the gaseous mixture with an aqueous solution of an alkali metal carbonate to form an aqueous solution of the alkali metal cyanide and the corresponding bicarbonate, (b) contacting the aqueous solution of (a) with a ketone to produce a cyanohydrin-ketone mixture immiscible in the aqueous solution and a regenerate the alkali metal carbonate, separating the alkali metal carbonate solution and returning it to the gas absorption step (a) and recovering the cyanohydrinketone mixture. Alternately, the cyanohydrin in the cyanohydrin-ketone mixture of step (b) can be decomposed to the corresponding ketone and hydrogen cyanide.

Abstract: To permit the processing of hydrogen sulfide-fixed nitrogen compound feed streams, e.g. H.sub.2 S-NH.sub.3 mixtures without causing plugging problems usually encountered in a Claus sulfur plant due to the formation of solid nitrogen sulfur salts, a first hydrogen sulfide feed containing substantial quantities of fixed nitrogen compounds, a portion of a second hydrogen sulfide feed essentially free of fixed nitrogen compounds and air are combined in a first thermal reaction zone where the amount of oxygen present is sufficient to achieve a high flame temperature for essentially complete conversion of the fixed nitrogen compounds to inert nitrogen, but insufficient to consume all of the hydrogen sulfide present. The effluent of the first reaction zone is combined with the balance of the second hydrogen sulfide feed in a second thermal reaction zone where hydrogen sulfide and sulfur dioxide react to form sulfur.

Abstract: Gas purification processes for removing hydrogen sulphide (H.sub.2 S) from a foul gas stream, such as coal carbonization gases, involving a circulating liquid reagent in which the H.sub.2 S is absorbed and converted to sulphur which is recovered and the reagent regenerated and recycled exhibit progressive deterioration of the circulating reagent due to contamination by process by-products. The invention provides a method of decontaminating such a circulating reagent by subjecting a bled-off sidestream to high temperature hydrolysis, so producing gaseous products recyclable to the foul gas stream. Solid products may also be produced which may be recycled to the reagent, perhaps after high-temperature reduction.

Abstract: A process for regenerating absorbent solutions used for removing gaseous impurities such as CO.sub.2, H.sub.2 S,HCN, SO.sub.2 and other acidic gases from gaseous mixtures by stripping with steam, which comprisesA. dividing the solution to be regenerated into a principal and a secondary fraction (p and s) and regenerating these fractions separately from each other in a principal and a secondary regeneration column (P and S), the principal regeneration column being operated at a pressure of at least about 0.2 to 0.5 atm above the pressure of the secondary regeneration column,B. regenerating the principal fraction in the principal regeneration column by heat which is fed from outside into the lower part of the column,C. regenerating the secondary fraction in the secondary regeneration column by heat which has been removed from the regenerated solution leaving the principal regeneration column andD. passing the regenerated fractions to the absorber.

Abstract: Ammonia, hydrogen cyanide and hydrogen sulfide contained in gas streams are separated from the gas streams by contacting the gas stream with an aqueous solution containing free oxygen for a time sufficient for the ammonia, hydrogen sulfide and hydrogen cyanide to react with the oxygen present to form ammonium thiocyanate and water for further treatment or disposal.One method of treatment is to thermally and catalytically convert for the ammonium thiocyanate to ammonia or nitrogen and hydrogen sulfide in the form of a second gas stream which is processed for recovery of any formed ammonia and the hydrogen sulfide.

Abstract: Gases containing hydrogen cyanide, ammonia and hydrogen sulfide are purified by first washing the gas with a suspension of solid sulfur to fix the hydrogen cyanide as ammonium thiocyanate and ammonium thiosulfate. The resulting suspension is then subjected to a wet-oxidation wherein the thiosulfate and a part of the thiocyanate is converted into sulfuric acid and ammonium sulfate afterwhich the resulting liquid containing unreacted thiocyanate is decomposed into an ammonium salt and is recovered from the oxidation and decomposition steps.

Abstract: Coke oven gases are washed with an aqueous metallic salt solution of sulfuric acid or sulfurous acid to absorb ammonia, hydrogen sulfide and hydrogen cyanide. The washing solution is then oxidized to recover elementary sulfur. A portion of the oxidized washing fluid is returned for continued washing of gas and a portion of the washing fluid is diverted to a separater where solid compounds which include metal hydroxide and metal cyanide compounds are removed leaving ammonium sulfate solution. The ammonium sulfate solution is heated with combustion air and in a heating agent to produce combustion products including nitrogen, hydrogen and an acid anhydride. The solid compounds from separater are conducted as a aqueous suspension to a reaction vessel wherein, at elevated temperature and pressure, hydrolysis products are formed including free ammonia, metal hydroxide and formate salts.

Abstract: Scrubbing solutions containing ammonium salts of weak acids are mixed with sufficient sulfuric acid to react with all the salts; the resultant solutions are evaporated by direct heat exchange with a hot SO.sub.2 -containing combustion gas to a 40-78% water content and combusted at 800.degree.-1,250.degree.C to produce the SO.sub.2 -containing combustion gas used in the evaporation step. The SO.sub.2 in the combustion gas can be processed in a conventional manner.

Abstract: A process is disclosed for the desulfurization of gases containing hydrogen sulfide, as well as their decyanization and removal of sulfurous acid when the gases contain hydrogen cyanide or sulfurous acid and in which process a napthoquino chelate compound is employed on a component of an absorption medium.

Abstract: In a process for the removal of hydrogen cyanide from raw gases containing at least one other acidic component selected from the group consisting of hydrogen sulfide, carbonyl sulfide and mixtures thereof comprising scrubbing said other components from the gases with a scrubbing agent, regenerating resultant loaded scrubbing agent, and recycling resultant regenerated scrubbing agent to the scrubbing step,The improvement wherein the hydrogen cyanide is scrubbed out simultaneously with the other acidic components, resultant loaded scrubbing agent is mixed with an aqueous alkali metal or alkaline earth hydroxide solution, and the thus-formed cyanide salt solution is thermally converted into ammonia and formate.

Abstract: A catalytic amount of ammonia or ammonium compounds are utilized to prevent deterioration of alkanolamines employed in gas sweetening processes. The ammonia is added either to the sour gas or the absorbing solution and acts to suppress thiocyanate .[.formation.]. .Iadd.accumulation .Iaddend.during absorption.BACKGROUND OF THE INVENTION1. Field of the InventionThis invention relates to gas purification and more particularly to gas purification by the removal of acid gases from industrial gas in an absorption/desorption process.2. Prior ArtThe term "gas sweetening" pertains to gas purification processes in which acid gases, particularly sulfurous gases are removed from industrial gases.Gas sweetening processes commonly utilize aqueous absorbing solutions into which the acid gases are scrubbed (absorbed) to be later stripped (desorbed) for possible further treatment. Desorbing is accomplished by heating the spent solution to expel the acid gases.