Abstract: In a method for producing a catalyst for oxidizing sulfurous acid gas which uses vanadium pentaoxide as a main catalyst, potassium salts as subsidiary catalysts and diatomaceous earth as a carrier; disclosed is a method for producing a parallel gas flow type catalyst for oxidizing sulfurous acid gas, characterized in that after an ingredient mixture of a solution containing vanadium pentaoxide and potassium salts, diatom earth, water and a binder containing sodium polyacrylate is knead, said ingredient mixture is extrusion molded into a shape in which gas passage holes have a honeycomb or grid structure.

Abstract: A solution or slurry containing a carbonate or sulfite, or both is continuously supplied into a tightly closed vessel, while any excess of the liquid is allowed to overflow the vessel. Sulfuric acid is supplied into the vessel to maintain the pH level of the liquid in the vessel at a value not exceeding 3. Air is supplied into the vessel as a carrier gas for CO.sub.2 or SO.sub.2 or both formed by the reaction of the carbonate or sulfite or both in the liquid with the sulfuric acid. The carrier gas is collected from the vessel, and the concentration of CO.sub.2 or SO.sub.2 or both in the carrier gas is determined. The concentration of the carbonate or sulfite or both in the liquid is obtained by calculations from the concentration of CO.sub.2 or SO.sub.2 or both, the flow rate of the liquid and the flow rate of the carrier gas.

Abstract: The present invention is directed to a method for treating a waste gas to separate and recover gypsum and a dust therein, characterized by comprising the steps of causing the waste gas to pass through a dry dust collector; introducing the gas into a gas absorber, in which a slurry containing at least one of calcium hydroxide or calcium carbonate as an absorbent is employed to remove SO.sub.2 and the dust passed through the dry dust collector from the waste gas; blowing air into the resultant absorbing liquid in the gas absorber to oxidize the absorbing liquid and to thereby produce gypsum; delivering them to an absorbing liquid tank, in which the slurry mainly containing the gypsum grains is separated from the other slurry mainly containing the dust by partition walls disposed therein; and directly taking out the respective slurries separately from the absorbing liquid tank.

Abstract: An exhaust fume desulfurization process is disclosed which comprises the steps of contacting an off-gas containing SO.sub.2 with a slurry containing calcium and manganese compounds, introducing a gas containing oxygen into the slurry, detecting the amount of the absorption of oxygen by the slurry, and regulating the amount of manganese present in the slurry based upon the amount of oxygen absorbed by the slurry. The desulfurization rate is correspondingly adjusted and the desulfurized gas product is recovered.

Abstract: A process for desulfurizing an exhaust gas which comprises desulfurizing an exhaust gas containing SO.sub.2 by bringing it into contact with a slurry containing calcium compounds and aluminum compounds, characterized in that the concentration of the dissolved aluminum ion in said slurry is detected and a manganese compound is supplied into said slurry in such a manner that the ratio of the concentration of manganese (including both solid and liquid) to said concentration of the dissolved aluminum ion may be maintained in a molar ratio of less than 1 in said slurry.

Abstract: In a first processor unit the relationship between the amount of nitrogen oxides in a combustion exhaust gas and a numerical value representing an amount of combustion, e.g. - fuel flow rate or the like, is stored. In a second processor unit the ratio of ammonia to nitrogen oxides as a function of the combustion exhaust gas temperature is stored. A numerical value corresponding to the actual measured amount of combustion is inputted to the first processor unit to derive the amount of nitrogen oxides in the combustion exhaust gas. The actual measured combustion exhaust gas temperature is inputted to the second processor unit to derive the ratio of ammonia to nitrogen oxides. The optimum amount of ammonia to be injected is derived by multiplying the amount of nitrogen oxides, derived by means of the first processor unit, by the ratio of ammonia to nitrogen oxides derived by means of the second processor unit.

Abstract: In a process and an apparatus for controlling oxides of nitrogen in exhaust gases from combustion equipment by decomposing the oxides, in the presence of oxygen, with ammonia blown into the equipment and associated ducting at temperatures within the range from 700.degree. to 1300.degree. C., a catalyst assembly is arranged, with the catalytic surfaces of the component units substantially in parallel to the direction of exhaust gas flow, in a region where the temperature of the gas after the decomposing treatment is between 300.degree. and 500.degree. C., and the gas after the decomposing treatment is caused to pass through the catalyst assembly to decompose residual nitrogen oxides and ammonia in the gas to innocuous substances. An additional supply of ammonia, in an amount from 0.5 to 1.

Abstract: A process for wet-treating an exhaust gas to remove oxides of sulfur and of nitrogen including:1. washing the exhaust gas with a slurry containing one or more magnesium compounds to remove oxides of sulfur from the exhaust gas;2. washing the exhaust gas treated in step (1) with an aqueous solution of an alkali metal iodide and/or an alkaline earth metal iodide to remove the oxide of nitrogen; and3. contacting the slurry from step (1) with the aqueous solution from step (2) to regenerate the solution of alkali metal iodide and/or alkaline earth metal iodide and to decompose any nitrite formed in step (2) to nitrogen.

Abstract: Nitrogen oxides and sulfur oxides are removed from exhaust gases in a two step process including a slurry removal of the sulfur oxides followed by washing the gases with an aqueous solution of an alkali metal iodide and/or an alkaline earth metal iodide.