Fluorine-chlorine removal tower and device and process for removing fluorine and chlorine from sulfuric acid by fluorine-chlorine removal tower

Abstract

The invention relates to a fluorine-chlorine removal tower and a device and process for removing fluorine and chlorine from sulfuric acid by the fluorine-chlorine removal tower. The fluorine-chlorineremoval tower comprises a tower wall with an inner fluoroplastic layer and an outer steel base material layer, an air interlayer is arranged between the fluoroplastic layer and the outer steel base material layer, and a metal porous plate is arranged between the air interlayer and the fluoroplastic layer which is adhered to the metal porous plate. The fluorine-chlorine removal tower has advantagesthat the tower and the air interlayer are both vacuumized internally, and the vacuum degree of the air interlayer exceeds that of the tower; in the tower, sulfuric acid containing fluorine or chlorine contacts with low-pressure saturated steam to be heated and contacts with water to evaporate, so that fluorine or chlorine is separated from sulfuric acid and discharged from the tower along with steam to realize purification. By low-pressure saturated steam for direct heating and steam stripping, steam heat and sulfuric acid dilution heat are fully used, overhead steam temperature of a steam stripping tower is lowered under the vacuum condition, and low operating cost is realized; high fluorine-chlorine removal efficiency is realized, and conditions are created for recycling of sulfuric acid.

Description

technical field [0001] The invention belongs to the technical field of sulfuric acid purification, and in particular relates to a chlorine removal tower and a process and a device for removing chlorine and fluorine in sulfuric acid by using the tower. Background technique [0002] Sulfuric acid is widely used in the chemical industry. In many production processes, the utilization rate of sulfuric acid is very low, and a large amount of sulfuric acid is discharged with acid-containing wastewater, causing harm to the ecological environment. If sulfuric acid is not recycled, it will cause waste of resources. In recent years, my country has strict requirements on the treatment of waste acid, and the continuous introduction and improvement of relevant policies and standards has paved the way for the development of the hazardous waste industry, pointed out the direction, and promoted the rapid development of my country's hazardous waste industry. [0003] Fluorine and chlorine ex...

AI Technical Summary

Problems solved by technology

The "Comprehensive Wastewater Discharge Standard" requires fluoride to be less than 20ppm, and the primary and secondary standards require less than 10ppm. None of the above processes can meet this requirement

[0004] Chinese patent CN205347085U discloses "a device for synchronously recovering sulfuric acid and fluorine and chlorine from polluted acid". The separation of fluorine and chlorine from sulfuric acid is achieved through electrodialysis, falling film evaporation and falling film absorption, and concentrated acid is obtained. The removal rate of fluorine and chlorine in sulfuric acid is as high as 95.6% and 94.7%. The process is complex and cannot completely remove fluorine and chlorine

Chinese patent CN105502307A discloses a "method and special device for concentrating and defluorinating polluted acid". It is concentrated by multi-effect evaporation to obtain polluted acid with a concentration of 25-40%, and then steam is passed through a reboiler + defluorination The chlorine tower removes hydrogen fluoride and hydrogen chloride, and the removal rate is above 95%. This process has a concentration limit for dirty acid and cannot completely remove fluorine and chlorine

Chinese patent CN106186135A discloses a "chlorinated waste sulfuric acid dechlorination device", which uses compressed air to remove free chlorine in the acid through a packing separation tower and a separation kettle, but chlorine exists in sulfuric acid in the form of chlorine gas in this system, which is not suitable for Sulfuric acid system in the form of hydrogen chloride

Therefore, the separation environmental conditions of high vacuum superimposed high temperature (relatively) is an ideal condition in engineering, but the ideal structure of the existing defluorination chlorine tower is generally a fluorine plastic lined tower wall structure, but this structure is at high temperature (≥120 ℃) and vacuum conditions, it is unreliable to work under the superimposed conditions. Under this condition, the interface between the lining fluoroplastic layer and the base layer (steel) is subjected to the superimposed effect of temperature difference stress and vacuum stress, which exceeds the tensile strength of the fluoroplastic material body, which will cause Lead to liner debonding failure, resulting in liner leakage and overall structural failure

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