DE743747C - Process for processing raw ammonia water - Google Patents

Description

Process for the processing of raw ammonia water In the manufacture of ammonium sulfate according to the G #, p! s procedure, a concentrated trotted. Ammön #, umcarb: onate solution with machined lenem plaster implemented. From the muddy The reaction mass is obtained by filtration Lime separated and the solution evaporated. This procedure is without difficulty with synthetic ammonia - manufactured- the ammonium, carb; onate solution. If raw ammonia water is used, how it z. B. as Gasivass; he during coking or smoldering of coal or also at the carbohydrate is incurred; `so bothers beside organic contamination in particular the content of hydrogen sulfide. It is' now known that the hydrogen sulfide is out the raw ammonia water by gassing with carbon dioxide in countercurrent or cocurrent and with or without the use of: increased Pressure can be aüsgetneh-ezi. Advantageous one works for this in a with Jüllkkörpers' sent. Tower in the opposite direction, with the Liquid through the on-iie ' for the subsequent reaction with gypsum, the most favorable temperature is brought to about 40 to 60 °; excess heat is removed, if necessary, by cooling the solution. In this way, for example, an ammonium carbonate solution with a temperature of qo to 50 ° is obtained which, per liter, contains between 15 and 160 g of ammonia and. Contains 30 to 150 g of carbon dioxide. The expelled sulfur water, serstaf has a high content of ammonia, which is withdrawn from the reaction with gypsum. B. in the Claus furnace, leads to malfunctions. In order not to have to absorb the ammaniac sulfuric acid for a long time, it can be removed from the gas coming from the expeller by washing with water. Since: this gas also contains carbonic acid, when using F1uI3 water, which usually contains a lot of lime, e.g. B. about 14o to 300m9 Ca 0 per liter, contains the packing of the water washing tower. and the lines through :. precipitated potash clogged. It is therefore necessary to use softened water or condensed water, which incurs additional costs.

It has now been found that these disadvantages can be overcome in a simple manner can thereby avoid the need to wash out the ammonia from the exhaust gas Desulfurization of a part of the resulting from the filtration of the lime sludge Using washing water. This contains ammonium sulfate, free ammonia and carbon dioxide, but only about 30 mg CaO per liter.

Because of its ammonium sulfate content, this wash water only has one poor dissolving power for carbonic acid and hydrogen sulfide; its absorption capacity Ammonia contained in the gas can be increased considerably if that free ammonia in the liquid through a separate pre-treatment with carbonic acid i! n bicarbenate is transferred. Surprisingly, in this way, the ammonia content of the gas can be reduced to o to o.5g / m3; one then needs to complete the whole Absorption of the ammonia only very small amounts of acid, e.g. B. sulfuric acid, which at the same time also absorbs pyridine bases contained in the gases, or can do without a wash completely.

To avoid contamination of the ammonium sulphate by organic compounds, like phenols, the raw ammonia water is used before desulphurisation expediently in a manner known per se with substances having an adsorptive effect, such as active Coal, treated, whereby the troublesome admixtures are removed. These will obtained in a concentrated form, so that, for. B. Phenols easily in the pure state can be won.

Does the exhaust gas formed during the defoliation contain organic impurities; like hydrocarbons, these can also be treated with active Coal or the like can be removed.

One embodiment of the method of the present invention is described below with reference to the accompanying illustration.

Ammonia water, which contains 155 to 2309 ammonia (of which r50 to 2i0 g as free ammonia), 30 to 180 g, preferably 50 to 120 g, carbon dioxide, 25 to suction, preferably 3o to 40 g, hydrogen sulfide and also small amounts of cyan and contains organic compounds, is introduced at i in the middle part of the Entsichtvefeltu @ gsko #! onn @ e A and treated in the flow stream with carbon dioxide, which kOInlIllt through line 2. At 3, an ammonium carbonate solution with only 0.1 to 1 liters of hydrogen sulfide flows into the line 7. It is stirred in container B with gypsum flour which is introduced at 8 ". The reaction material is processed, for example, on a belt-like filter device C. At ii it collects a concentrated ammonium sulfate solution, which usually still contains small amounts of ammonium carbonate and which is based on solid ammonium sulfate The lime sludge freed of sulphate with fresh water fed in at 12 is discharged at 13. Part of the scrubbing liquid goes back to the filter device via lines 14 and 15; another part is sent via line 16 to the top of column A at 4 and brought into contact here with the gas containing hydrogen sulphide which escapes from the lower Kolo@nnenit.eil; the ammonia is washed out of the gas Sulfuric acid, to be absorbed To increase the absorption capacity of the washing liquid for ammonia and for To reduce their ability to absorb hydrogen sulfide, it can be advantageous to treat them beforehand in the tower 9 with carbon oxide, which can be pure or diluted by inert gases. It is added at io; at I 0a either unabsorbed carbonic acid or the inert gas accompanying the carbonic acid flows, e.g. B. pure hydrogen in the case of the use of hydrogen-containing carbonic acid from the pressurized water purification for separating carbon dioxide from mixtures of carbon dioxide and hydrogen. In the lower part of the column A, the liquid warms up due to the action of carbonic acid, the ammonia to 50 to 70 ° and above, which promotes the expulsion of the hydrogen sulfide without any other supply of heat. Since the liquid located here mixes with the washing liquid coming from the upper part of the column, an ammonium carbonate solution is immediately obtained with a temperature of 40 to 60 °, which is advantageous for the subsequent reaction with gypsum. If necessary, excess heat is removed by pumping part of the liquid in the upper part of the column with the interposition of a cooler 6 in the circuit.

With a column about 80o mm in diameter and 22 m in height, 5 to 10 m3 of crude ammonia water of the above composition can be processed per hour in the manner described to form an ammonium carbonate solution with 0.1 to 10 g hydrogen sulfide per liter. You need 0.5 to 2.5 m3 of washing liquid every hour; The carbon dioxide consumption depends on the content of unbound ammonia and carbon dioxide in the raw ammonia water and amounts to 300 to 95o ms per hour (based on 20% carbon dioxide). The hydrogen sulfide content in the off-gas from the column is about 30 to 50 percent by volume and above with a content of crude ammonia water of 30 to 409 hydrogen sulfide per liter.

Instead of the raw ammonia water from coking plants and gas works, you can other solutions containing sulfur ammonium can be processed in a corresponding manner. The method of the invention is also for expelling. from hydrogen sulfide diluted raw ammonia water is suitable, but is with a low content of unbound ammonia is the heat of reaction resulting from decomposition with carbonic acid to carry out the deswe:, e_una process not sufficient .. Therefore, in in this case Wäime are supplied as steam or in some other form, e.g. B. by Ammonia is introduced into the desulfurization column as a gas or concentrated solution will. The ammonia content can be. of the diluted raw water increased so much be that the @desulfurized ammonium carbonate solution is one for the reaction with Plaster of paris has a suitable concentration.

One can also proceed in such a way that the raw ammonia water in the described Way desulphurized and only part of the ammonium carbonate solution running off with gypsum is implemented while the other part after a treatment in one. in; Coking plants conventional deacidifier with lime. is distilled. You can also be part of the solution Process on solid ammonium carbonate. For this purpose, the temperature of the solution flowing out of the column kept at 5o to 6o °; their concentration per liter must be from 1 to 1 6o g of ammonia and from 3o to 15o g of carbon dioxide. When such a solution is cooled to 20 ° and below, a mixture of ammonium carbonate falls and bicarbonate, .das in a known manner by decanting or filtering the mother liquor is separated.

The process of the invention has the technical advantage that the desulfurization at a pressure of 2 to 5 m water column can be carried out as it is adjusts easily at the above-mentioned loading of a reaction tower. It is also of importance that the free sulfuric acid for the saturator operation on The mines are replaced by the sulfuric acid of the gypsum and at the same time by the hydrogen sulphide of the crude ammonia water can be easily recovered in a concentrated form can.

Claims (2)

PATENT CLAIMS: i. Process for processing raw ammonia water by desulfurization - using gaseous carbon dioxide and subsequent conversion the obtained ammonium carbonate solution with gypsum, characterized in that the at the levitation: ung anfal_end.e, in we_-entlichen from Sichwe:, hydrogen and Carbon dioxide existing exhaust gas to remove the ammonia carried along with the when washing the ka: kschlamm @ that left behind during the implementation with plaster of paris. Waschflüasägkei @ ge.:asc:.@ei will. 2. The method according to claim i, dadu.- ch characterized in that the washing liquid is first treated with carbonic acid or gases containing it. To distinguish the subject of the application from the state of the art, the following publications were taken into account in the granting procedure: German patent specification ..... No. 375 309; Das Gas- und Wasserfach, 76th year 1933, p. Log to log.