Technology of synthesizing high concentration chlorosulfonic acid using low concentration salfur trioxide

Abstract

A process for synthesizing high-concentration chlorosulfonic acid from low-concentration SO2 features that the SO3 generated by directly decomposing the fuming sulfuric acid by the fume converted from sulfuric acid and the hydrogen chloride are used as raw materials. Its advantages are wide range of the concentrations for hydrogen chloride, and little environmental pollution.

Description

technical field [0001] The invention relates to a synthesis process of chlorosulfonic acid. Background technique [0002] At present, there are many manufacturers of chlorosulfonic acid in China. It is composed of sulfur trioxide and dry hydrogen chloride gas at a temperature of 150-230 ° C. According to the concentration of sulfur trioxide in raw materials, it is divided into low gas concentration method and high gas concentration method. : [0003] In the low gas concentration method, the temperature of the sulfuric acid plant is 200-260°C, the conversion rate of sulfur dioxide is 90-95%, the concentration of sulfur trioxide is 7-10%, and the volume content of the by-products from the chlor-alkali plant is more than 90% or more. The volume content of the by-product of the Hamm method potassium sulfate plant is 25-35%, and the temperature is 20-60°C. Dry hydrogen chloride gas is used as raw material, and it is synthesized by main and auxiliary reactions, cooled and separat...

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Problems solved by technology

The main disadvantages of this method are: (1) due to the high concentration of sulfur dioxide in the raw material, the utilization rate of total sulfur is low

(2) Since sulfur dioxide does not participate in the reaction, the concentration of sulfur dioxide in the tail gas is much higher than the value allowed by the national standard. A large amount of alkali will be consumed when washing with alkaline water, and the waste liquid must be treated before it can be discharged, and the cost will increase significantly.

If it is not washed with alkali, it will not be able to meet the discharge standards at all.

(3) After the waste gas is washed with water, the dilute hydrochloric acid obtained directly enters the sewage treatment, without recycling, and increases the amount of alkali when washing with alkaline water, which also increases the production cost

Although this method overcomes the shortcomings of the traditional low gas concentration method, such as low total sulfur utilization rate, large tail gas discharge and large alkali consumption during alkaline water washing, and reduces the cost of raw materials, it still has defects: (1) with 8-10kg / cm 2 Saturated steam or reforming furnace gas is used as heat source to indirectly heat free sulfur trioxide with a concentration of 20-30% oleum, and the temperature of niacin is about 150°C. Although corrosion-resistant alloys are used, the equipment materials still have a large corrosion rate. The main equipment The life of the evaporator is generally not more than one year, which often leads to irregular shutdown, and the cost and difficulty of replacement are very high

(2) If steam heating is used, the evaporator is a pressure vessel, once the steam leaks into the sulfuric acid, there will be a danger of explosion

(3) If the flue gas is used for indirect heating, the heating area is large and the heat consumption is large; the liquid film in the tubes is unevenly distributed, which often leads to local overheating and serious corrosion

(4) Due to the high corrosion rate of the equipment, the iron content in the desorbed niacin is high, which affects the quality of niacin

(5) From the perspective of heat balance, the heat carried by the raw material sulfur trioxide cannot satisfy the situation of using low-concentration hydrogen chloride as a raw material similar to the by-product of the Mannham process potassium sulfate plant

(6) Tail gas is absorbed by lye and discharged, and the waste liquid after pickling and water washing cannot be returned to the system for recycling

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