SU791399A1 - Gas cleaning method - Google Patents

Description

(54) METHOD FOR CLEANING GASES

one

The invention relates to processes for the purification of exhaust gases from acidic components, namely sulfuric and sulfuric anhydride, fluoride, phosphorus pentoxide, and can be used to purify sinter gases in the production of phosphorus. Sulfurous anhydride is the main harmful component in ethic gases.

The known methods of gas cleaning allow extracting only separate components of the mixture Jl.

A known method of purifying gases with soda solutions at the same time from several acidic components. Waste solutions after single use are sent to the neutralization station. With the simultaneous presence of sulfuric acid, fluorine and phosphorus in the gases to be purified, a mixture of sulphite-bisulphite, sulphate, fluoride and sodium phosphate is formed when treating gases with soda solutions.

The disadvantage of the method is the one-time use of a deficient copolymer solution, due to the impossibility of regeneration of the latter by sulphates, which leads to the formation of wastewater, as well as a low degree of gas purification.

The degree of gas purification with a one-step absorption scheme with soda solutions for phosphoric anhydride is 5O%, hydrogen fluoride is 96%, sulfurous anhydride is 70% and sulfuric anhydride is 7O%.

The purpose of the invention is to increase the degree of gas purification and eliminate the formation of wastewater.

15

The goal is achieved in that the absorption is carried out in two steps, in the first step 5-1O% sodium acetate solution is used as the aqueous solution of sodium salts 20, and in the second step the lime suspension is formed and absorbed on the second stage. Neither calcium acetate solution is used to regenerate the spent first-stage diluent. When the content of sodium acetate is below 5%, the required sorption capacity of the solution and the reaction rate are not provided. At a concentration of above 10%, precipitation of sodium fluorides and sodium phosphates is possible. The drawing shows a process diagram. 8, absorber 1 of the first stage is used to absorb harmful impurities with a solution containing 5-1% sodium acetate solution. The bulk of the solution through the circulation sump 2 is pumped 3 again to the absorber, and part is brought to the precipitator reactor 4. for regeneration with calcium acetate solution, which is supplied in an amount equivalent to the total salt content. The recovery solution 4, which contains sulfite, sulfate, phosphate, sodium fluoride and sodium acetate acetate remaining in solution, enters the reactor-precipitator 4 for regeneration from the first absorption stage. These salts react with calcium acetate with the formation of insoluble salts of sulfite, sulfate, phosphate, and calcium fluoride, which precipitate. The precipitate is filtered on a vacuum filter or centrifuge 5 and sent to a sludge collector 6, and a flrate (or a centrate) containing sodium acetate is taken in step 1 of absorption. The mechanical loss of sodium acetate is supplemented by the addition of soda and acetic acid. Acetic acid vapor is pressed in the second stage scrubber 7 with lime milk. Through the same scrubber passes the gas to be purified, which increases the degree of gas purification. Achieved a degree of gas purification for phosphoric anhydride 75%, hydrogen fluoride 99.9%, sulfurous anhydride 95%. Example 1. Gas containing, mr / nm: $ 02 1350; SOj. 5O; HF 2О and 80, are cleaned in the scrubber of the first stage with the initial 1O% sodium acetate solution to concentration. 4 mg / nm: SO2405; SOjlS; HP 0.8; 4O and enters a second-stage scrubber, which is irrigated with lime milk with a concentration of 100 g / l. The gas in the second stage scrubber is purified to residual concentrations, mg / nm:, 0; OZ 2.5; HF traces; 20. In the process of trapping the acidic components in the first-stage scrubber, acetic acid vapors are separated and carried away by gas to the second-stage scrubber, where they are collected with lime milk. The circulating solution from the first stage is taken out for regeneration in the amount of 60 m V4 with salt content, g / l: 94.5; Naj, S04 3.55; NaF 2.1; 3.55; CHjCOOMa 3.1. From the second stage, 3.5 suspensions with a concentration of salts, g / l: CaSOj 5.6; Ca $ OdO, 2; CaF 0.007; Sa, (PO), Oh, Sa (OH) | 34.0; Ca (CH, COO), 132.3. In the process of regeneration, insoluble calcium salts Ca5Od, Ca $ 0 are formed. CaFji, CasfPO). Insoluble salts are formed in an amount, kg / h: Ca $ 0Z54; Ca, 4; 11.7; Ca (PO) 2 23.7. Sodium acetate produces 811.8 kg / h. After regeneration, the solution is filtered, centrifuged, the dumps are dumped, and the clarified solution and filtrate (centrate) are returned to the first-stage absorption cycle. Example 2. The gas composition of example 1 is purified by a known method 15) soda solution to residual concentrations, mg / nm: HF 0.8; 4O. The spent solution in the amount of 5 is poured into the neutralization station with salt content, g / l: Ma 50z 94.5; , 55; ME2. 3.55; NaP 2.1. It is impossible to regenerate this solution, since sodium sulf87a does not regenerate, sodium sulfate accumulates in the irrigated solution, which has a bad effect on the absorption of acidic components. The table shows the data on the stage of gas purification by the proposed and known methods.

Claims (2)

1. Smooth V. A. Overview. Modern methods of cleaning the exhaust gases of industrial, large-scale cities from sulfur dioxide, GOSINTI, 1976 2. Halperin S. L, et al. Works of LenNIIGIPROCHIM, vol. 19, p. 1316, Ld, 1975. / %; j "a "50 CS H "about