Sulfuric acid process

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This process uses sulfur as the raw material, and uses the one-turn-one-suction contact method to produce 98% sulfuric acid and 104.5% oleum, which are used as the company's own raw materials. The main reaction steps of sulfur acid production are as follows:: a) Liquid sulfur burns with oxygen in dry air in the incinerator to generate sulfur dioxide furnace gas, and releases a large amount of heat. The reaction equation is: Ｓ＋Ｏ2＝ＳＯ↑＋Ｑb) Under the catalysis of the vanadium catalyst in the converter, the sulfur dioxide and oxygen in the furnace gas are contacted and oxidized to form sulfur trioxide gas, and a large amount of heat is released. The reaction equation is: 2ＳＯ＋Ｏ2＝2ＳSO3↑＋Ｑ c) Sulfur trioxide gas combines with the water in the spray acid to generate sulfuric acid in the 98% sulfuric acid absorption tower (packed tower). The reaction equation is: ＳＯ＋Ｈ2Ｏ＝Ｈ2ＳＯ＋Ｑd) 98% sulfuric acid continues to absorb sulfur trioxide gas in the oleum tower to generate 104.5% oleum. The raw sulfur is weighed by a handcart and put into a molten sulfur pool. It is indirectly heated and melted with saturated steam. After the sulfur is melted, it undergoes static precipitation and slag removal. A sulfur pump is used to send the liquid sulfur to the sulfur incineration furnace. It is burned in the furnace together with the air sent from the drying system to generate SO2 gas and release a large amount of heat. The dry air required for sulfur combustion is supplied by a Roots blower. The air enters from the bottom of the 76% sulfuric acid drying tower (foam tower, referred to as the one-dry tower), and comes into contact with the sulfuric acid sprayed from the top of the tower. Most of the water in it is absorbed by the sulfuric acid. The air comes out from the top of the tower and then enters the 95% sulfuric acid drying tower (packed tower, referred to as the two-dry tower). It contacts the sulfuric acid sprayed from the top of the tower, and the moisture in the air is further absorbed. The dried air comes out from the top of the second drying tower and enters the wire mesh demister to remove the sulfuric acid foam entrained in the air. Part of the air with the acid foam removed passes through the internal heat exchangers between the first and second sections and the fourth and fifth sections of the converter and then enters the incinerator together with the dry air from the main air duct. The other part of the air with the acid foam removed enters the first, third and fourth sections of the SO2 converter to adjust the conversion temperature. The high-temperature SO2 furnace gas from the sulfur incinerator enters from the bottom of the sulfur dioxide heat exchanger and exchanges heat with the soft water. The temperature of the SO2 furnace gas is lowered. At the same time, the soft water is heated into steam. The steam is drawn from the heat exchanger drum for use by liquid SO3 and/or molten sulfur. The soft water required for the sulfur dioxide heat exchanger is supplied from the soft water tank and sent into the heat exchanger through a pressurized water pump. After the cooled SO2 furnace gas comes out of the heat exchanger, part of it is led to the sodium sulfite manufacturing and liquid SO2 manufacturing processes. ； Most of the SO2 furnace gas enters the SO2 gas filter through the 8# butterfly valve. At the same time, a small amount of high-temperature SO2 furnace gas is introduced from the incinerator outlet into the filter through the heat exchanger auxiliary line to adjust the reaction temperature of the conversion stage. The SO2 furnace gas entering the filter removes ash and slag and then enters the first catalyst layer of the converter (counted from top to bottom), and passes through the second, third, fourth and fifth catalyst layers in sequence. The SO2 gas is converted into SO3 gas, releasing a large amount of heat. Most of the heat released by the reaction is taken away by the air in the internal heat exchanger. The SO3 furnace gas from the converter enters the sulfur trioxide cooler for natural cooling. The cooled SO3 gas enters the 98% sulfuric acid and/or oleum absorption tower. The absorbed tail gas comes out from the top of the tower and is purified by the sulfur tail absorption tower before being discharged into the atmosphere along the exhaust pipe. The high-concentration sulfuric acid after absorbing SO3 gas flows into the acid circulation tank from the bottom of the tower, and low-concentration sulfuric acid is continuously added to adjust the circulating acid concentration. The adjusted circulating acid is sent to the sulfuric acid cooler by the circulating pump. Most of the cooled circulating acid enters the absorption tower as splash acid. ； Another part of the circulating acid is led from the cooler outlet to the sulfuric acid storage tank as semi-finished acid.