SU709524A1 - Method of preparing sulfur dioxide - Google Patents

Description

one

The invention relates to methods for producing sulfur dioxide, intended for use in pulp and paper production and other branches of the national economy of the country.

A known method of producing sulfur dioxide when burning sulfur in air under pressure up to 50 atm with an air excess factor of more than 1.0, followed by cooling. M and purification of the resulting gas 1.

The closest to the proposed method to the technical essence and the achieved result is the method according to which the combustion of sulfur is carried out under pressure close to atmospheric, in rotary and nozzle furnaces, fluidized bed and cyclone-type devices, and cooling is performed in two steps with water first, up to 300, and then up to 40 ° С, combining this process with gas cleaning from mechanical impurities and partly from chemical impurities.

The purified and enclosed sulfur dioxide is directed to absorption by water or solutions of bases, thus obtaining the "sulphite acid used in the production of cellulose 2.

A disadvantage of the known methods for producing sulfur dioxide is that in their implementation the content of dioxide

sulfur in the resulting gas is not npeBbinjaeT 17%. and the content of sulfuric anhydride in germanium, the formation of which leads to a direct loss of sulfur in production, reaches 0.2%. The technical and economic efficiency of the preparation of sulphite acid is determined mainly by the strength of the sulfur dioxide used and it turns out that the gas is more concentrated.

The aim of the invention is to increase the concentration of sulfur dioxide and prevent the formation of sulfuric anhydride.

Claims (1)

This goal is achieved by the fact that, in the proposed method, sulfur is burned at a coefficient a in the range of 0.1 -, 0, regardless of the type of oxygen-containing gas used (air, technical oxygen, oxygen-enriched air), and gas cooling at the first stage, the temperature of the wash liquid is 115-158 ° C, and at the second stage the gas temperature is reduced to 30-35 ° C. The cooling of the gas in the first stage to 115-158 ° C, in contrast to the known method (300 ° C), is due to the need to prevent the adherence of sulfur, which is decondensed from the vapor of the cooled gas, and to remove it from the system in an easily mobile liquid state. The most favorable conditions for this are created in the proposed temperature range, the viscosity of the liquid sulfur in which is minimal and is in the range of 0.065-0.126 P. The decrease in gas temperature to 30-35 ° C in the second stage of its washing and cooling is determined by the sulfur dioxide sorption from gas in sulphite pulp production. Example. The method was tested on the unit with an air excess factor of 0.1 and a = 1.0, at a pressure of 3, 0 atm. Sulfur burning in air at a pressure of 3.0. aI is performed as follows. Solid sulfur is fed to a melter, where it is converted into a liquid state using steam. The molten sulfur is collected in a collection, from where it with a temperature of 140 ° C is continuously fed under pressure to the combustion unit for combustion. The air required for burning sulfur is compressed by compressor up to 3.0 MPa and after heating in the furnace casing up to 180-200 ° C is fed to the furnace unit. Regulation of the sulfur burning temperature in the range of 1100-1300 ° C is made by changing the flow rate of water injected into the furnace by a special nozzle. The coefficient of excess air OS is maintained at 0.1 or 1.0. The oxygen of the air supplied to the furnace is completely consumed for the formation of sulfur dioxide. In addition to nitrogen and sulfur dioxide, kiln gas contains significant amounts of vaporous sulfur. The latter is removed from the gas, previously condensed to a liquid, lightly mobile state. For this, the hot vapor-gas mixture leaving the kiln unit is cooled in two stages in direct contact with thoroughly sprayed water. The first hot gas cooling stage is most efficiently performed in a venturi-type scrubber. The gas-liquid mixture thus formed is separated in a cyclone separator. With the hot wash liquid (115-158 ° C), condensed sulfur is removed in the molten state with various impurities contained in the burnt sulfur (selenium and others). In a heat insulated settling tank, where the washing liquid from the cyclone separator flows, two layers are formed. The bottom layer is liquid sulfur with heavy impurities settling in it, and the top layer is hot (115-158 ° C) washing liquid. Periodically, part of the molten sulfur with selenium, tellurium and other heavy contaminants (cracks) deposited in it is discharged from the sump, poured into containers and sent to specialized facilities for processing as it accumulates. The main amount of liquid sulfur (the upper part of the lower layer in the sump of the washing liquid) is returned to the collector in front of the kiln unit, where it is displaced with fresh molten sulfur sent for incineration. The hot (115-158 ° C) washing liquid is displaced with a part of the washing water formed in the second stage of the washing, and after cooling it is sent for reuse. Sulfur dioxide, cooled in the second stage to 30-35 ° C, is fed to the absorption apparatus for the preparation of tower acid. The concentrations of sulfur dioxide produced during the combustion of sulfur in the air, both at aO, I and a 1.0, are close to theoretical - 21 / o.The implementation of the proposed method ensures the production of sulfur dioxide theoretical concentration free of selenium, sulfuric anhydride and other harmful substances. chemical technology cellulose technologies. The use of such gas in sulphite-pulp production will reduce the cost of building acidic departments of enterprises, significantly reduce pollution of the atmosphere with exhaust gases of the sorption equipment, increase the strength of sulfite acid, intensify the cooking of wood and significantly improve the quality indicators of the products. Claims A method for producing sulfur dioxide by burning sulfur under pressure in air or oxygen-containing gas, followed by two-step cooling and washing the resulting sulfur dioxide, characterized in that, in order to increase the concentration of the target product, sulfur is burned with an excess air or oxygen-containing gas ratio a 0.1 -1.0, and gas cooling at perj7095244 The first steps lead to temperament-I. French Patent .Kfai5I5691, tours of the washing liquid 115-158 ° C, ACL. Since 01, 1968. at the second stage, the gas is cooled to 30-35 ° C2. Nepenin N. N. Pulp technology. Sources of information, volume I. Production of sulfite cellulose, taken into account during the examination. 152-155, 1956 (prototype).