Method for using sulphur gas for reducing waste sulfuric acid to prepare liquid sulfur dioxide and sulfuric acid

Abstract

The invention relates to a method for using sulphur gas for reducing waste sulfuric acid to prepare liquid sulfur dioxide and sulfuric acid. Sulphur is gasified into the high-temperature sulphur gas,the raw material waste sulfuric acid is washed, evaporated, concentrated and split into gas, the two streams of gas is reacted in a reduction furnace to make sulfur trioxide in the waste sulfuric acidsplit gas reacted with the gas sulphur to generate sulfur dioxide gas, organic matters, powdered carbon and the like in the waste sulfuric acid split gas generate sulfur dioxide, carbon dioxide, carbon monoxide, nitrogen, hydrogen chloride, water and the like, reduced furnace gas is subjected to complete combustion, waste heat recovery, purification and drying to obtain sulfur dioxide gas, part of the sulfur dioxide is liquefied to prepare a high-purity liquid sulfur dioxide product, and sulfur dioxide-containing gas which is not liquefied and the other part of the sulfur dioxide gas are mixed, and are subjected to conversion and absorption to prepare the concentrated sulfuric acid. Compared with the prior art, the method has the advantages that low temperature is used for conducting purification, concentration and regeneration resource utilization on the waste sulfuric acid to prepare high-quality liquid sulfur dioxide and concentrated sulfuric acid products, meanwhile, impurities ofthe organic matters, salt and the like in the waste sulfuric acid are subjected to proper harmless treatment, no secondary pollutants are generated, and resource recycling and environmental friendliness are achieved.

Description

technical field [0001] The invention relates to chemical products, in particular to a method for producing liquid sulfur dioxide and sulfuric acid by reducing waste sulfuric acid with sulfur gas. Background technique [0002] The existing chemical production uses concentrated sulfuric acid as a catalyst and dehydrating agent. After being used in the production process, the concentration of sulfuric acid decreases and contains organic matter, salt and water. The concentrated sulfuric acid becomes waste sulfuric acid and sulfur-containing waste liquid. These production units include alkylation units for increasing the octane number of gasoline, sulfuric acid titanium dioxide units, pigment units, acrylonitrile units, methyl methacrylate units, nitration units for explosives and pesticides, chlor-alkali units, acetylene units, ferrous acid units Washing device, hydrofluoric acid drying device, sulfonation device, etc. If the industrial waste sulfuric acid is not properly dispo...

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Problems solved by technology

[0005] (1) High-temperature incineration regeneration needs to consume a lot of fuel and energy, and the operating cost is high;

[0006] (2) Combustion produces a large amount of CO 2 Together with the nitrogen and other inert gases brought in by the air, existing in the furnace gas reduces the furnace gas SO 2 concentration, which increases carbon emissions and pollutes the environment;

[0007] (3) CO produced by burning fossil fuels 2 And bring into the air, etc., the furnace gas contains SO 2 Low concentration, large equipment specifications for purification, conversion and absorption systems, high power consumption, high investment, and high cost of regeneration of waste sulfuric acid;

[0008] (4) Nitrogen in the fuel and air will undergo side reactions during high-temperature incineration to generate NO and NO 2 , the product concentrated sulfuric acid will also contain impurity HNO 2 、HNO 3 , the acid color is deep, affecting the quality of the finished acid, and the final exhaust gas will also contain NO X , will inevitably pollute the environment

Though there is the liquid ambient temperature condition of maintaining reaction temperature 200~250 ℃ in this invention application process, this temperature is corresponding to w(H 2 SO 4 ) 79-89% boiling point temperature of sulfuric acid solution, at this temperature, the water vapor in the reactor will evaporate, increasing the concentration of sulfuric acid. The evaporation intensity on the surface of the kettle is very limited. To maintain a high concentration of sulfuric acid in the reactor, the volume of the reactor and the evaporation surface area must be large enough to make the reaction time long enough; while the volume and area of ​​the actual reactor in a large-scale industrial production device are Limited, it is difficult to maintain the decrease of sulfuric acid concentration caused by the consumption of sulfuric acid in the reaction, which will definitely affect the reaction efficiency and the progress of the reaction. is completely broken down

[0013] (2) Cannot effectively remove organic impurities in waste sulfuric acid

The composition, content, and properties of organic matter in waste sulfuric acid are complex, and contain organic matter with different boiling points; organic matter with a boiling point lower than the reaction temperature of 200-250°C will volatilize into the gas phase, while the boiling point of organic matter such as tar will be higher than the reaction temperature. Boiling point organic matter and coke are still in the liquid at this temperature, and most of these high boiling point organic matter and coke are relatively low in activity in the liquid state at this temperature, and it is difficult to react and decompose in the liquid phase; and in the reactor Continuous accumulation will increase the viscosity of the reaction material, and the boiling point will also change with the accumulation of impurities, and will wrap the liquid sulfuric acid and sulfur, which will further affect the reaction efficiency and prevent the waste sulfuric acid from decomposing and reacting completely.

In the application process, it is stated that the organic matter entering the gas phase is separated from sulfur dioxide gas when cooled by cooling water, but the liquid condensed from the gas phase contains water, dilute sulfuric acid (converted from a small amount of sulfur trioxide), and organic matter, which belongs to sulfuric acid. How to dispose of low-concentration organic wastewater is a problem, and there is no description of how to deal with it; in addition, the application process does not describe how to dispose of unreactable waste sulfuric acid and high-boiling organic matter in the residual reaction liquid. Hazardous chemical wastes that are difficult to dispose of; therefore, this process has no effective measures for the treatment of impurity organic matter in waste sulfuric acid. If the discharge system is bound to cause serious harm to the environment, this process does not consider harmless while considering resource utilization. problem solving

[0014] (3) The organic impurities in the waste sulfuric acid raw material cannot be utilized, and the sulfur consumption is high

Under the temperature conditions of the application process, organic impurities are almost unable to react with sulfuric acid due to their low reactivity

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