Abstract: A method for regenerating a spent alkanolamine absorbing solution containing absorbed H.sub.2 S and CO.sub.2 in two desorption stages to produce two separate acid gas streams. The first acid gas stream that contains substantially all of the H.sub.2 S is sent to a sulfur recovery system and the second acid gas stream that is primarily CO.sub.2 is vented to the atmosphere. The desorption stages are connected in series and both are operated at substantially the same above-atmospheric pressure within the range of 8-12 psig (1.54-1.82 atm abs).

Abstract: A method for cooling naphthalene containing gas streams using recirculated cooling water comprising physically separating suspended naphthalenic solids from the used cooling water, injecting a water immiscible solvent for naphthalene into the clarified cooling water, and vigorously mixing the solvent and cooling water to form a dispersion which is recooled in an indirect heat exchanger without serious buildup of naphthalenic solids in the heat exchanger and recycled to cool the gas stream.

Abstract: Integrating an absorption-desorption step, a Claus plant, and a catalytic hydrogen reactor in a recycle loop provides a gas-desulfuration plant that operates at a substantially zero emission level. Hydrogen sulfide is removed from industrial gas streams by absorption-desorption in a liquid absorbent. The resulting foul gas is then reacted with sulfur dioxide in a Claus reaction, i.e., the reaction of hydrogen sulfide with sulfur dioxide to form elemental sulfur and water. The tail gas from this Claus reaction is then passed through a catalytic hydrogenation reactor together with a supply of hydrogen to reduce the sulfur and sulfur compounds to hydrogen sulfide. The now reduced tail gas is then recycled back to the industrial gas, upstream of the absorption-desorption step.

Abstract: Nitrilotriacetonitrile (NTN) is produced in high yeilds from hydrogen cyanide, formaldehyde and ammonia, or its equivalent as an ammonium salt of a strong acid, by utilization of a critical two-stage reaction sequence within a narrow dilution ratio and temperature range. The reaction sequence steps provide for a first mixture to be prepared comprising a mixture of the formaldehyde and ammonia. No external adjustment of the pH of this mixture is permitted. A second mixture is prepared comprised of the HCN in an aqueous solution and a strong mineral acid such as sulfuric acid for adjusting the pH of the mixture to about 1 or less. NTN is produced by combining the mixtures at a temperature of from about 55.degree. C. to about 70.degree. C. either by adding the formaldehyde/ammonia solution to the HCN/acid solution or vice versa. The ratios and dilution of the reactants is critical for good yields.

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.