SU20648A1 - Modification of the method for producing high concentration ammonia gas from ammonia water described in patent number 3856 - Google Patents

Description

Patent No. 3856 describes a method for producing high concentration ammonia gas (directly from raw ammonia water, which implies that vapors of ammonia, water, and volatile solvents evolved when the raw ammonia water is heated in a column apparatus, after being passed through a flame lamp, is further subjected to cooling below the dissociation temperature of carbon dioxide and sulfuric mmonium, for the purpose of carbon dioxide and hydrogen sulfide release In the form of solid deposits of carbon dioxide and ammonium sulphide. m are periodically removed from the condensers and, after evaporating them, the resulting gases are treated with WATER, in order to trap ammonia from the resulting gas mixture, which is returned to the column apparatus, while carbon dioxide and hydrogen sulfide are removed In a gaseous state. from the condensers of these deposits, by evaporating them, requires an additional consumption of steam for heating the mixture, which is unfavorable for the entire method.

In general, and, in particular, in those cases when it is necessary to use raw weak ammonia water, - ammonia water of HIGH concentration as the starting material in the production of ammonia gas.

Further, the authors of the proposed modified method have found that it is possible to significantly reduce steam consumption, if concentrated ammonia water before being sent to the distillation column to release all ammonia, pass through the apparatus (dissociator) to partially remove ammonia and hydrogen sulfide. This technique facilitates the operation of ammonium carbonate capacitors and increases the amount of free ammonia produced from each ton of recycled water. However, as is known, it is impossible to pass concentrated ammonia water through a dissociator, because the temperature conditions for the release of carbon dioxide and hydrogen sulfide require heating and 94 °. In order to have the OPPORTUNITY to reach this temperature without large losses of ammonia, it is necessary to process ammonia solutions with a strength not higher than NHg.

In order to eliminate the aforementioned difficulties, in the proposed method, dilution of concentrated ammonia water to the specified limit is produced with the help of hot waste water flowing from the distillation column. This method of using waste water from the specified column to dilute strong ammonia water makes it possible to eliminate the additional steam consumption for heating the mixture, which could make the dissociation method unproductive to remove impurities in the gaseous form.

The modified method for producing pure ammonia gas from concentrated ammonia as shown in the schematic drawing is that the destillation column 8, which is heated by entering through conduit 21, is isolated. from the ammonia water introduced into it, ammonia together with impurities of water vapor, carbon dioxide, hydrogen sulfide and

Other volatile substances, which are delayed in deflamators 9, in the associator 10 of the wash column 12, and the pure ammonia gas is discharged through the pipe 24 to the gasholder. Concentrated ammonia water from reservoir 6 is sent to dissociator 7, designed to partially remove impurities from ammonia water and carbon dioxide and hydrogen sulfide impurities, which are removed from the upper part of the apparatus, irrigated with clean water from reservoir 16, for washing purposes ammonia gases. Concentrated ammonia water entering the middle part of the dissociator to pipe 26, h; mixed with hot water pumped by pump 5 of the lower part of column 8. Diluted ammonia water readily transfers carbon dioxide and hydrogen sulphide to / from impurities and flows through pipe 28, 29 to the upper part of the distillation column 8 so as to undergo complete, release from ammonia there. A closed circular process established between the dissociator 7 and the column 8 allows heat to be reused; delivered; my steam flowing through pipe 21. The application of the described method for producing ammonia from concentrated ammonia water, according to the instructions of the authors, is equally suitable as in cases where ammonia in aqueous solutions is associated with carbon dioxide and hydrogen sulfide. so and

in that case

when part of the ammonia is free. The more free ammonia is contained in ammonia water; the higher the performance of the proposed installation. If a concentrated ammonia gas is needed for production, all ammonia water must first be passed through a simple distillation column, operating without lime, for the purpose of liberating with moderate heating of free ammonia, and only that only ammonia, carbon dioxide and with hydrogen sulfide, direct this water to the dissociator 7 and column 8 for final release from ammonia. Experiments have shown that free ammonia, not contaminated with hydrogen sulfide, can be isolated with moderate heating and concentrated water, if the temperature in the upper plates of the distillation column does not exceed 60 °. Thus, the installation for the separation of ammonia from concentrated ammonium-valued water containing only ammonia in the form of carbonic acid salts and hydrogen sulfide and the other part of ammonia in the form of a solution of the free base consists of two consecutive connected distillation columns: one for distilling a distillate column, and the second is for decomposition of ammonium salts / Such a combination of two columns is used, for example, in the preparation of pure ammonia gas, in order to liquefy strong S solutions of ammonium hydrochloride. fabrication of the urea ammonium salt of carbamide, for the manufacture of sodium amide, and so forth. In the same cases, when dd production there is no need to produce 1000 / o-ny ammonia gas and, in particular, when it is necessary to have a mixture of ammonia with air, as is required for the fabrization of nitric acid by the method of contact oxidation of ammonia with atmospheric oxygen, The method described above can be modified to some extent. For example, if the starting material is concentrated ammonia water, containing a row of salts

ammonium and some amount of free ammonia, the latter can be; isolated from an ox by blowing air through it at a moderate temperature. By blowing away almost all free ammonia can be removed without contaminating the ammonia mixture with hydrogen sulfide and other impurities of an acidic nature. An apparatus for the release of ammonia by blowing through air or another gas represents the same conventional column with plates and caps through which air is blown through pump 2 into the lower part, while towards the air on one of the upper plates, column 3 flows from tank 1 concentrated water When warmed up in the reshoffer 17. Coming down from one plate to another, the water loses free ammonia and is discharged into reservoir 4, containing only bound ammonium salts. From tank 4 by pump 5, the solution of bound salts is pumped into the dissociator 7 and the distillation column 8. The air-ammonia mixture formed in the column apparatus 3 is discharged through pipe 18 to the contact apparatus for oxidation to E133. In order to protect the ammonia-air mixture from contamination with hydrogen sulfide and carbon dioxide impurities that may be entrained from the concentrated water, one or several tops, their plates from column 3 are irrigated with clean water or ammonia solution coming through the pipe 19. Thus, the washing device is not able to trap ammonia, but easily holding hydrogen sulfide and other acids, Regulation and concentration. ammonia in the gas mixture is achieved by heating the bottom plates of the column, for which lead coils are placed on the latter, steam is circulated through the KOTOpbiM. In order for the apparatus to get the ammonia-air mixture to have a stable mode, i.e. would give gaeovuyu; a mixture with a constant composition of ammonia, which is very essential for the correct operation of the contact apparatus, the column must have a large heat capacity,

/ i.e. contain a relatively large amount of ammonia water. On the other hand, the air for saturation with ammonia up to 10 percent and higher must pass through the column relatively slowly. Longer tests of the auto show showed that when purging, the temperature in such a column decreases by 18-20 ° below atmospheric, if the bottom plates are not heated. It was also noted that the amount of free ammonia obtained by prolonged purging with concentrated ammonia water is slightly higher than determined by the initial analysis of ammonia water. At the same time, part of the hydrogen sulfide is oxidized with prolonged air blowing to release sulfur from free ammonia. The process of hydrogen sulfide oxidation can be accelerated by the addition of heavy metal salts, especially manganese, iron and nickel. The partial oxidation of sulfur-Dorrda can represent a significant benefit in the organization of production, because hydrogen sulfide is usually an admixture for contact.

The subject of the patent.

1. Modification of the method of obtaining high concentration of ammonia gas: from ammonia water, marked. in patent No. 3856, characterized in that, when using a source of concentrated ammonia water as the starting material, the latter is pre-diluted with hot waste water flowing from the distillation column, and the resulting diluted mixture is passed through a dissociator, in order to remove part of the carbon dioxide and hydrogen sulfide in the gaseous state, after which the partially purified water is distilled from the ammonia hydrogen sulfide and carbon dioxide in the distillation column. 2. Acceptance of the method indicated in para. 1, characterized in that using ammonia water containing free ammonia as a starting material, the latter is removed either by moderate heating in a separate distillation column or by blowing air at a moderate temperature, after which the remaining solution of ammonium salts is diluted with hot water and treated in a dissociator and a distillation column.

3. Modification of the method of producing ammonia gas, according to p. 2, based on the fact that for the oxidation of part

hydrogen sulfide, in the case of air blowing with concentrated ammonia water, is added to the water to dissolve the same metals as, for example, the salts of manganese, iron and nickel.

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