SU1154203A1 - Method of obtaining highly concentrated gaseous sulfur dioxide - Google Patents

Abstract

A method of producing high-sulfur-centered gaseous sulfur dioxide by absorbing sulfur dioxide from sulfur dioxide with a circulating aqueous solution of sulfite, bisulfite, and ammonium sulfate, followed by thermal desorption of sulfur dioxide from the solution, withdrawing a portion of the circulating solution to remove the sweater, and the body of the product. circulating solution, characterized in that, in order to reduce the loss of the target product with the solution discharged from the cycle, the ammonia water is preliminary (L n The mixture is mixed with added water to a molar Shd / HgO ratio of 0.1-0.2, followed by separation of the solid suspensions thus formed.

Description

SP

The invention relates to methods for the preparation of highly concentrated sulfur dioxide and can be used in the production of detergents of sodium hydrosulfite, cellulose, in the food industry as a preservative. The purpose of the invention is to reduce the loss of the target product with the solution removed from the cycle. The method of producing highly concentrated sulfur dioxide gas consists in absorbing sulfur dioxide from sulfur dioxide with a circulating aqueous solution of sulfite, bisulfite, and ammonium sulfate, followed by thermal desorption of sulfur dioxide from the solution, extracting part of the circulating solution to remove the ammonium sulfate and simultaneously adding ammonia. the ammonia water is preliminarily mixed with the added water to a molar ratio of MnH / HgO of 0.1-0.2, followed by separation it forms solid suspended solids. When preliminarily treated with ammonia water or ammonia, water with the above molar ratio is fed into the circulating solution, the concentration of free ammonia in the solution of ammonium sulfate, bisulphite and ammonium decreases with the concentration gradient of free ammonia. with sulfur dioxide. Local overheating reaching in the known methods leads to a sharp increase in the rate of oxidation of the solution and to the self-decomposition of sulfite and ammonium bisulphite, and, consequently, to the loss of sulfur dioxide, ammonia and water. In addition, preliminary mixing of ammonia water with added water to a specified ratio leads to the formation of solid ammonia complex compounds with variable valence metal impurities dissolved in water, which are catalysts for the oxidation of sulfur dioxide in the liquid phase to form ammonium sulfate. The drawing is a diagram of the devices explaining the proposed method. Sulfuric acidic gas entering the absorption line passes through the products of the ion absorber 1 irrigated with a concentrated solution of sulfite, bisulfite and ammonium sulfate supplied by pump 2 from tank 3 and sanitary absorber 4 irrigated with a weak solution of sulfate, bisulfite and ammonium sulfate supplied by pump 5 from the tank 6. After sanitary cleaning, the gas is emitted into the atmosphere through the spout 7. The solution of sulfur dioxide containing sulfur dioxide enters the tank 8, from where pump 9 transfers part of the solution to the heat exchange Nick 10, where it is heated and fed to the thermal desorption stage to the desorber 11 equipped with a boiler, ohm 12, and part of the solution is withdrawn as commercial ammonium bisulfite to remove the ammonium sulfate formed during the absorption stage. Sulfur dioxide emitted in the desorber-11 through condenser 13 is sent to the consumer, and the circulating solution cooled in heat exchangers 10 and 14 enters the container 3 of the absorber 1. Preparation of a fresh solution instead of output from the circulation cycle as a commercial product is carried out by adding ammonia or ammonia water to the water in the mixer 15, where the impurities contained in the water are distributed. From the mixer 15, the mixture cleaned of solid impurities is sent to the containers 6 and 3. If necessary, the absorption cycles of the sanitary absorber 4 and the production absorber 1 can be separated. In this case, the need to treat the water supplied to the preparation of the irrigating device 4 solution disappears, and the solution of sulfite, bisulfite and ammonium sulfate obtained at this stage is directed to decomposition with sulfuric acid to form a 35-40% solution of ammonium sulfate. Example. Sulfur dioxide is supplied to the absorption, with which 2440 kg / h of sulfur dioxide is supplied. At the absorption stage, 239 kg / h of sulfur dioxide is absorbed by the sulphite, bisulphite, ammonium sulphate solution. This oxidizes

23.9 kg / h of sulfur dioxide and forms 49.3 kg / h of ammonium sulfate, which must be removed from the cycle. To remove this amount of ammonium sulfate, 25 solutions are removed, including 35 and 106 kg / h of ammonium sulfite and ammonium sulfate salts. Ammonia must be supplied to compensate for ammonia losses and water with gas and ammonium sulfate removed. 42 , 46 kg / h and water 501 kg / h. This amount of ammonia and water is fed to the pretreatment stage of water in the form of ammonia water and process water, where 544.1 kg / h of a mixture with a molar ratio is formed

1542034

NHj / HjO 0.1. In this case, a solid sediment formed by the interaction of ammonia water with impurities dissolved in water is removed from a solution of 0.015 kg / h. The clarified mixture containing impurities of 1-3 mg / l is fed into the absorption cycle. - At the stage of thermal desorption, 10 2230 kg / h of sulfur dioxide is consumed from the circulating solution.

Thus, in the proposed method, the loss of ammonia and sulfur dioxide with the solution removed to remove ammonium sulphate is 41.82 and 112 kg / h, respectively (in the well-known method, the loss is 184 kg / h of ammonia and 468 kg / h sulfur dioxide).

Claims (1)

METHOD FOR PRODUCING A HIGHLY CONCENTRATED GAS SULFUR DIOXIDE by absorbing sulfur dioxide from sulfur dioxide by a circulating aqueous solution of sulfite, bisulfite and ammonium sulfate, followed by thermal desorption of sulfur dioxide from the solution, withdrawing part of the circulating solution to remove ammonium sulfate and water and ammonium sulfate and water and characterized in that, in order to reduce the loss of the target product with the solution withdrawn from the cycle, ammonia water is pre-mixed with added water to a molar ratio of NH ₃ / H ₂ O 0.1-0.2, followed by separation of the resulting solid suspensions. SU, ..1154203>