SU852800A1 - Method of purifying aqueous solutions from hydrogen sulfide - Google Patents

Description

(54) METHOD FOR CLEANING AQUEOUS SOLUTIONS FROM HYDROGEN

one

The invention relates to methods i for purifying water from hydrogen sulphide and can be used in the gas industry to purify solutions from. hydrogen sulfide before their rectification.

Currently for. prevent hydrate formation in a number of gas fields; methanol is pumped into the wells, which after ot. divisions from the gas in the separators are subjected to rectification. Methanol is diluted with water in the wells, and calcium, magnesium, and bicarbonate ions are contained in the coils. If hydrogen sulfide is present in the produced gas, then solutions 15 also contain hydrogen sulfide, which makes rectification difficult, causing equipment corrosion and environmental pollution. This necessitates the purification of solutions before distillation from hydrogen sulfide.

A known method of purifying water from hydrogen sulfide l, in which alkali and alkaline earth metal chlorites at pH 6 are used for oxidation of hydrogen sulfide, being strong oxidizing agents, chlorides can react with methanol present in the solution, causing its loss and deterioration., G, Ig. process indicators 30

. The closest in technical essence to the proposed method is the method by which water purification: from hydrogen sulfide is carried out with hydrate, iron oxide, and regeneration is formed. All of the iron sulfate is carried out by blowing air 2.

 This method does not provide complete purification of aqueous solutions from hydrogen sulfide. The regeneration of the solutions is carried out by air blowing, and this greatly complicates the technology and increases the cost of the process.

If for rc sources the threefold excess of iron doxide is taken and during the regeneration four times air purging is performed, then the degree of purification of the solution from hydrogen sulfide in the presence of methanol is only 67%.

The precipitation of calcium and magnesium carbonate in the form of scale leads to equipment corrosion and complications. cleaning system and during the rectification of solutions.

The aim of the invention is to increase the degree of purification of aqueous solutions from hydrogen sulfide in the presence of methanol.

The goal is achieved by mixing aqueous solutions with geleramide chloride, neutralizing it to a pH of 7.5-8.5, separate 1 yt iron sulphide, and regeneration is carried out by decomposing iron sulfide with hydrochloric acid, followed by returning ferric chloride to the process. The drawing shows a schematic diagram of the process of purification of aqueous solutions from hydrogen sulfide. Aqueous solutions containing hydrogen sulfide are fed into the pipeline, into which a solution of ferric chloride is pumped into pump 1. The resulting mixture is sent to reactor 2, in which the required amount of alkali is added to achieve a pH of the mixture of 7.5-8.5. The resulting iron sulfide is separated from the solution on filter 3. The filtrate is sent for rectification, and iron sulfide for treatment with hydrochloric acid in reactor 4. The hydrogen sulfide that has been separated is fed to the slightest process, and the resulting iron chloride solution is returned at the beginning of the process. Example 1. An aqueous solution containing 136 mg / l of hydrogen sulfide and 50 methanol in an amount of 1000 ml is purified. To do this, 0.51 g of ferric chloride is added to the solution, and then 0.56 g of sodium hydroxide is neutralized. The resulting sulphide of the glands is filtered off and the concentration of hydrogen sulfide is determined in rastvor. The latter is not in solution. Thus, the proposed method provides 100% purification of an aqueous solution containing mehanol from hydrogen sulfide. Example 2; An aqueous solution containing, kg / m, hydrogen sulfide 5, Calcium 3.3, magnesium 0.9, bicarbonate ions 2.4 and methanol 50%, in an amount of 1 m with a specific weight of 1000 kg / m 3 is mixed with 54 kg of a 34% ferric chloride solution. Then, 12 kg of ammonia is added to the mixture to achieve a pH of 8. After the iron sulfide formed is separated, hydrogen sulfide and bicarbonate ions are not detected in the solution. The filtered iron sulfide is treated with 24 kg of 30% hydrochloric acid. In this way, 3.3 m of hydrogen sulfide and a solution of ferric chloride are returned, which is returned to the beginning of the technological cycle. Adding alkali to the solution to neutralize the solution to a pH of 7.5-8.5 is necessary, since calcium and magnesium ions are included in the aqueous solution with methanol. If the pH of the solution after the addition of alkali is above 8.5, then calcium hydroxide and magnesium hydroxide will precipitate from the solution, which together with the sulfide will enter the acid treatment stage. This will inevitably lead to an increase in the consumption of hydrochloric acid and, accordingly, alkali in the precipitation of calcium and magnesium, which will worsen the technical and economic indicators of the process. Example 3. A 1 m aqueous solution containing .kg / m, hydrogen sulfide 5, calcium 3.3, magnesium 2.4 and methanol 50% is mixed for purification with ferric chloride solution, then alkali is added to the mixture to neutralize the solution and the iron sulfide formed is treated with hydrochloric acid. Data on alkali consumption and acid treatment of 1 m solution at pH 8.5 and pH 8.5 are summarized in the table.

11.9 6.6 7.9 26.4

35.8 19.9 23.8 79.5 Iron ion concentration at various pH values of solutions from which iron sulfide precipitates, equal to 0; 12; 3; four; five; 6; 7, is, respectively, Yu, 10 10-, 10 10-8 umol / l. When iron sulfide is precipitated with ferric chloride from a solution containing hydrogen sulfide, equilibrium is established at. With such acidity, the bicarbonate ion is completely destroyed, but at the same time the acidic medium does not allow the hydrogen sulfide to be completely bound to insoluble ferrous sulfide. To ensure complete extraction of hydrogen sulfide, it is necessary to increase the pH of the reaction mixture to 7.58, 5. The pH value is determined by the fact that it is necessary to completely transfer to the solid phase an excess of iron ions that have not reacted with hydrogen sulfide. The chosen pH value ensures complete precipitation of iron. The limits of consumption of ferric chloride are determined by its solubility in water at various temperatures. The maximum solubility of ferric chloride at -9 ° C is 14.5 wt.% Its maximum concentration is 36.20 wt.%. The process of purification of aqueous solutions of hydrogen sulfide in the presence of methanol at a higher temperature is irrational, since there will be significant losses of methanol. The amount of ferric chloride that needs to be pumped to bind hydrogen sulfide into ferrous sulfide is significantly less than in the case of suspension of iron hydroxides.

Claims (2)

Caustic soda. According to the proposed method of cleaning is provided; 100% purification of aqueous solutions of hydrogen sulfide in the presence of methanol. DETAILED DESCRIPTION OF THE INVENTION A method for purifying aqueous solutions from hydrogen sulphide by treating with iron compounds and then regenerating them, characterized in that the aqueous solutions are mixed with ferric chloride and neutralized to pH 7.5-8 in order to increase the purity of solutions from hydrogen sulphide in the presence of methanol. , 5, iron sulfide is separated, and regeneration is carried out by decomposing iron sulfide with hydrochloric acid, followed by returning the iron chloride to the beginning of the process. Sources of information taken into account in the examination 1. For the FRG 2223790, cl. C 02 C 5/04, 1976. 2.Kl chko V.A., Lpeltsin N.E. Water treatment for industrial and urban water supply, M., stroiizdat, 1962, p. 691-693.