Method and devices for producing biuret and cyanuric acid

FIELD: chemistry.

SUBSTANCE: method of producing biuret and cyanuric acid through thermal decomposition of urea involves cooling the product of thermal decomposition of urea in order to settle crystals which are then dissolved in an aqueous alkaline solution and cooled to obtain high-purity biuret, and after neutralising the filtered mother solution with acid, cyanuric acid crystals are settled to obtain a suspension of cyanuric acid crystals which is then filtered to separate the crystals and washed. The invention also relates to devices for realising the given methods.

EFFECT: development of a cheap and simple method of producing biuret and high-purity cyanuric acid.

19 cl, 2 ex, 1 dwg

 

This application claims a right to the privileges of the Korean application No. 10-2006-0076212, filed August 11, 2006, in the Korean Intellectual Property Office, the contents of which are fully incorporated here by reference.

The technical field to which the invention relates.

The present invention relates to methods and devices for biureta and cyanuric acid, and in particular, to a method for biureta high purity in which the products of thermal decomposition of urea, such as biuret, triuret, cyanuric acid, cooled with the formation of a crystalline substance, which is dissolved by using an alkali solution and cooled with getting biureta high purity equipment to obtain biureta, as well as to a method and apparatus for producing cyanuric acid of high purity, which is a side product of the reaction of thermal decomposition of urea.

The level of technology

In the General case, when thermal decomposition of urea at 130C-200C, is formed condensation product containing biuret. The reaction of thermal decomposition of urea is carried out effectively if the process takes place under reduced pressure, or ammonia, which is the product of thermal decomposition of urea is removed by blowing air or nitrogen through the reactor, so that biuret may receive the n in large quantities over a short period of time. In addition, since the reaction of thermal decomposition occurs at high temperature, biuret can be formed quickly, but it can produce a greater number of by-products, such as cyanuric acid, triuret and melamine ("Biuret and Related Compounds", Chemical Reviews, 56, pp.95-197 (1956)).

Next will be described the process of thermal decomposition of urea with education biureta.

Urea is heated to 130C. or higher in the reactor thermal decomposition, with the formation of ammonia and isocyanates acid as shown in reaction scheme 1:

The reaction takes place according to scheme 1 as urea absorbs heat. With increasing temperature the urea decomposes faster and solanova acid is also formed faster. The more ammonia is removed, the more likely it is a direct response.

Solanova acid reacts with urea remaining in the reactor, with the formation of biureta by reaction scheme 2:

Reaction 2 is exothermic. As the temperature is raised, solanova acid present in large quantities in equilibrium, reacts with urea to form biureta. It also produces by-products such as cyanuric acid and triuret.

Similar processes of obtaining biureta the yli previously described in many references, which focuses primarily on methods of separation biureta large quantities of by-products after its formation.

The US patent No. 3057918 describes the allocation method biureta, in which the crude biuret containing the cyanuric acid and triuret, vivariums in aqueous ammonia solution with a concentration of 10% or more at 80-110C, and then cooled with the formation of crystalline biureta, poorly soluble in water. Published U.S. patent also discloses a method of separation of purified cyanuric acid from the solution, which was dedicated biuret, by removing ammonia under reduced pressure. The above-described method, however, requires a separate complex equipment to maintain the concentration of ammonia in solution at a given level, while the process of digestion is carried out under pressure. In addition, the process of digestion must occur over a relatively long period of time, from 30 minutes to 2 hours. In addition, the allocation of cyanuric acid should be carried out under reduced pressure. Thus, the method described above is expensive.

Published patent GB No. 1324277 discloses a method of obtaining biureta high purity, in which the urea is dissolved in a glycol ether and reacts when 110-210C To produce biureta high pure is s. This method, however, involves the decomposition of urea and the process of reducing the amount of residual urea to below the required level by lowering the temperature, the process of reducing the amount of residual urea must be completed within 2-6 hours. Thus, this method is also expensive.

Thus, there is a need to develop an inexpensive method in which urea is thermally decomposed using a relatively simple method of obtaining biureta high purity.

Disclosure of inventions

The present invention is a method of obtaining biureta high purity using the reaction of thermal decomposition.

The present invention is also a method of obtaining cyanuric acid of high purity from the reaction products of thermal decomposition.

The present invention is also a device for receiving biureta high purity using the reaction of thermal decomposition.

The present invention also provides a device for producing cyanuric acid of high purity from the reaction products of thermal decomposition.

The result of the invention is to increase the purity biureta and cyanuric acid.

According to one aspect of the present invention presents a method of obtaining b is ureta, which includes: (a) melting of urea; (b) implementation by heating thermal decomposition of molten urea; (c) adding water to the resulting product of thermal decomposition for the deposition and filtration of the crude crystalline biureta; (d) dissolving the crude crystal biureta using an aqueous alkali solution; (e) cooling the dissolved product to precipitate crystals biureta; and (f) filtering the cooled product to obtain a crystalline biureta and the mother liquor and washing the crystalline biureta.

According to another aspect of the present invention presents a method of obtaining cyanuric acid, which comprises: (a) melting of urea; (b) implementation by heating thermal decomposition of molten urea; (c) adding water to the resulting product of thermal decomposition for the deposition and filtration of the crude crystalline biureta; (d) dissolving the crude crystal biureta using an aqueous alkali solution; (e) cooling the dissolved product to precipitate crystals biureta; (f) filtering the cooled product to obtain a crystalline biureta and the mother liquor and washing the crystalline biureta; (g) neutralizing the filtered mother liquor, received on the stud and (f), using acid to obtain a slurry containing crystals of cyanuric acid; and (h) filtering and washing the slurry containing crystals of cyanuric acid to isolate crystals of cyanuric acid.

According to another aspect of the present invention presents a device for receiving biureta, which includes: (1) the urea melter to melt urea; (2) reactor thermal decomposition thermal decomposition of molten urea by heating; (3) the first crystallizer to obtain a suspension containing the crude crystals by adding water to the product obtained in thermal decomposition reactor and cooling the resulting solution; (4) the first step of filtering and washing to obtain crude crystals biureta by filtration and washing the suspension containing the crude crystals; (5) capacity for dissolution to dissolve the crude crystals biureta using an aqueous alkali solution; (6) the second mold to obtain a suspension containing purified crystals biureta, by cooling the dissolved product; and (7) the second stage of filtering and washing the slurry containing crystals biureta.

According to another aspect of the present invention, the equipment for receiving the Oia cyanuric acid, which includes: device described above, namely: (1) the urea melter to melt urea; (2) reactor thermal decomposition thermal decomposition of molten urea by heating; (3) the first crystallizer to obtain a suspension containing the crude crystals by adding water to the product obtained in the reactor thermal decomposition, and cooling the resulting solution; (4) the first step of filtering and washing to obtain crude crystals biureta by filtration and washing the suspension containing the crude crystals; (5) capacity for dissolution, to dissolve the crude crystals biureta using an aqueous alkali solution; (6) the second mold to obtain a suspension containing purified crystals biureta, by cooling the dissolved product; and (7) second stage filtration and washing in order to filter the suspension containing purified crystals biureta and the mother solution, and rinse the cleaned crystals biureta; (8) neutralizing device for neutralizing the mother liquor fed from the second device for filtering and washing with acid to precipitate crystals of cyanuric acid to obtain a slurry containing crystals of cyanuric acid; and (9) the third stupa is filtering and washing the filter, and washing the slurry containing crystals of cyanuric acid to isolate crystals of cyanuric acid.

If biuret obtained using the method and device for obtaining biureta in accordance with the present invention, the crude crystals biureta, which is the product of thermal decomposition, dissolved in an aqueous alkali solution in a short period of time, and the resulting solution is cooled with selective allocation biureta having low solubility in water at low temperature, and, thus, can be obtained biuret with a high degree of purity. In addition, after the selected biuret, the mother liquor containing the cyanuric acid can be neutralized with acid to obtain crystals of cyanuric acid of high purity.

The implementation of the invention

The method of obtaining biureta according to the implementation of the present invention includes: (a) melting of urea; (b) carrying out the reaction of thermal decomposition of molten urea by heating; (C) adding water to the resulting product of thermal decomposition for the deposition and filtration of the crude crystals biureta; (d) dissolving the crude crystals biureta using an aqueous alkali solution; (e) cooling the dissolved product to OSA is the origin of crystals biureta; and (f) filtering the cooled product to obtain crystals biureta and mother liquor, and washing crystals biureta.

In (a), the temperature of the melt 12 of urea used for melting the urea may be in the range from 130C to 160C, more precisely from 132C. to 140C. If the temperature of the melt 12 of urea is less than 130C., the urea may not be completely melted. On the other hand, if the temperature of the melt 12 urea more than 160C, the reaction occurs samarangense and increased formation of by-products. After the urea is melted in the melt of urea, the urea is introduced into the reactor 13 thermal decomposition and heated.

In (b), the heating temperature may be in the range from 130C to 200C, more precisely from 140C to 150C. In this temperature range, the urea can react quickly and effectively with isocyanates acid. When the heating temperature is less than 130C, can be fused urea, and the reaction efficiency of education isocyanates acid may be too low. On the other hand, when the heating temperature more than 200C; too many side products, such as cyanuric acid, triuret, melamine, or Amelle, can be formed in addition to biuret.

The method may further include the return of gaseous ammonia and gaseous isocyanato acids is, formed in stage (b), stage (a). At the stage (b) reaction of thermal decomposition can be carried out in air or inert gas in the lower part of the reactor. With the introduction of air or inert gas in the lower part of the reactor ammonia and unreacted solanova acid may be present in the air or inert gas emerging from the reactor and, thus, ammonia and unreacted solanova acid can be re-introduced into the melter 12 urea. In melter 12 urea reentered solanova acid can react with urea to form biureta. Therefore, the degree of conversion of urea in the reaction of thermal decomposition can be increased. Ammonia can pass through the scrubber to absorb water, and then apply for the installation of liquid ammonia or aqueous ammonia solution of a given concentration.

The reaction of thermal decomposition can be performed in a single batch reactor or in a continuous reactor of the type consisting of a set of reactors connected in series. To increase the efficiency and stability of the reaction of thermal decomposition can be used reactor continuous action, which is more effective than periodic reactor. When the number of reactors exceeds 7, the increase is of the degree of conversion is no longer happens and thus, the economic efficiency may decrease.

The products obtained by the reaction of thermal decomposition may include biuret and by-products, such as cyanuric acid, triuret or similar. In the present description, the term "crude biuret" refers to a product containing biuret and other by-products. The crude biuret from the reactor 13 thermal decomposition is introduced into the first mold 14 and is then mixed with water, the mixture is cooled to precipitate crude crystals biureta to obtain a suspension containing the crude crystals biureta. Suspension of the crude crystals biureta filtered in the first stage 15 of the filtering and washing, and then fed into the container 16 for dissolution. In the first device for filtering and washing can be used centrifuge or equipment for vacuum filtration.

At the stage (C) the mother liquor may contain mainly urea; urea is fed into the device 23 for evaporation of water and heated under reduced pressure to evaporate water. The obtained urea re-introduced into the melter 12 urea for the production of biureta.

The crystals are filtered in the first stage 15 of the filtering and washing, i.e. the crude crystals biureta, can be dissolved in water RA the creators of alkali. The aqueous alkali solution may be an aqueous solution of alkali metal hydroxide or an aqueous solution of the hydroxide of the alkali earth metal, namely an aqueous solution of NaOH, KOH or Ca(OH)2. The concentration of alkali in the aqueous solution may be in the range from approximately 10% to 50%. An aqueous solution of alkali dissolves biuret, cyanuric acid and triuret, forming a solution, more precisely, reacts with cyanuric acid with the formation of salts, greatly increasing the solubility of cyanuric acid. Accordingly, an aqueous alkali solution, which is added to react with cyanuric acid with the formation of salt should be used in the corresponding equivalent with respect to cyanuric acid. According to the present invention, the amount of the alkaline solution may be in the range from 0.5 to 5 moles per 1 mole of cyanuric acid in the crude crystals biureta. When the amount of the aqueous alkali solution is too small, producing less salts of cyanuric acid and, respectively, in the cooling process may not be biuret high purity. On the other hand, when the number of used alkaline aqueous solution is too high, the concentration biureta too low, and biuret cannot be deposited in the subsequent cooling process.

At stage (d) an aqueous alkali solution may be the objavlen at a suitable temperature, in order to achieve efficiency and stability of dissolution. According to the present invention, the temperature of dissolution may be in the range from 50C to 105C, more precisely in the range from 60C to 80C. When the temperature of dissolution below 50C, the time of dissolution of the crude crystals biureta in aqueous alkali solution may be too large, and thus, the economic efficiency will be lower. On the other hand, when the temperature of dissolution above 105C, biuret can decompose, and thus, the quantity will decrease.

The solution obtained by using an aqueous alkali solution in stage (d), cool. The cooling process can be carried out through the cooling heat exchanger spiral plate or tubular type. In this implementation, the cooling process can be carried out at temperatures from 5C to 40C. When the cooling temperature is less than 5C, a solution of the crude biureta becomes so viscous that it can be technological problems. On the other hand, when the cooling temperature above 40C, only a small number biureta can be obtained in the form of sediment due to the high solubility biureta. In the process of cooling biuret having low solubility in water, may be precipitated in the form of crystals, but cyanuric acid, which exists in the de salt, can completely disappear.

The resulting suspension of crystals biureta is filtered and washed in the second stage 18 of the filtering and washing with the aim of identifying crystals biureta. Selected crystals biureta dried to obtain crystals biureta high purity, which is the aim of the present invention.

The method of obtaining cyanuric acid according to the present invention, includes: (a) melting of urea; (b) carrying out thermal decomposition of molten urea by heating; (C) adding water to the resulting product of thermal decomposition for the deposition and filtration of the crude crystalline biureta; (d) dissolving the crude crystal biureta using an aqueous alkali solution; (e) cooling the dissolved product to precipitate crystals biureta; (f) filtering the cooled product to obtain a crystalline biureta and the mother liquor and washing the crystalline biureta; (g) neutralizing the filtered mother liquor obtained in stage (f)using the acid in order to obtain crystals of cyanuric acid, with formation of a suspension of crystals of cyanuric acid; and (h) filtering and washing the slurry of crystals of cyanuric acid to isolate crystals of cyanuric acid.

Thus, the method according to the teachings of cyanuric acid, under this option includes the same processes as in method corresponding to the previous version of the implementation, namely: the implementation of thermal decomposition of molten urea by heating; adding water to the resulting product of thermal decomposition order of deposition of the crude crystals biureta and filtering the crude crystals biureta; dissolution of crystals biureta using an aqueous alkali solution; cooling the dissolved product to precipitate crystals biureta; and filtering the crystals biureta;

At stage (g) salt of cyanuric acid is neutralized with acid. In the present invention, the acid may be an inorganic acid, such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, or organic acid, such as acetic acid, carbonic acid, formic acid, oxalic acid or benzoic acid. In addition, the acid can be any acid having a pH less than 7.

The crystals precipitated by neutralizing the acid mother liquor at a stage (g), contain large amounts of cyanuric acid. The suspension of crystals is filtered and washed with water in the third stage 20 filtering and washing to obtain cyanuric acid of high purity.

A device for receiving biureta according to described the mu version of the present invention includes:

(1) the urea melter for melting urea;

(2) reactor thermal decomposition thermal decomposition of urea by heating;

(3) the first crystallizer to obtain a suspension of the crude crystals by adding water to the product obtained in the reactor thermal decomposition, and cooling the obtained product;

(4) the first step of filtering and washing to obtain crude crystals biureta by filtration and washing the suspension of the crude crystals;

(5) capacity for dissolution to dissolve the crude crystals biureta in an aqueous solution of alkali;

(6) the second mold to obtain a suspension of purified crystals biureta by cooling the dissolved product; and

(7) second stage filtration and washing for filtering suspensions of purified crystals biureta to obtain purified crystals biureta and the mother solution and rinse the crystals purified biureta.

The absorber 11 of ammonia, the melter 16 urea reactor 13 thermal decomposition, the first and second molds 14 and 17, the first and second stages 15, 18 and 19 filtering and washing, and the 16GB for dissolution of alkali as described above.

The device according to the present variant implementation may further include a device for absorption of gaseous ammonia gazoobraznoi isocyanates acid, formed in the reactor 13 thermal decomposition, and return the collected gas in the melter 12 urea. As a result of use of such returns device can be minimized loss of unreacted gaseous isocyanates acid, and, accordingly, may be increased the rate of conversion of urea in biuret. At the same time, the ammonia formed in the reaction of thermal decomposition, is passed through the absorber 11 so that the ammonia was absorbed in the absorber 11 and then sent to the plant for liquid ammonia or ammonia water, a certain concentration, and thus, could be used in other processes.

The reactor 13 thermal decomposition can be either periodic reactor or reactor continuous operation, consisting of multiple reactors connected in series. In order to achieve efficiency and stability of the reaction of thermal decomposition, can be used reactor continuous action, which is more effective than periodic reactor. When the number of reactors is greater than 7, increase the degree of conversion no longer occurs, and thus, the economic efficiency may decrease.

The device according to the described variant implementation may additionally include a device in which ispar what is the water from the mother liquor, received in the first device for filtering and washing (4), and the resulting solution is fed into the melt of urea (1). The mother liquor obtained in the first stage of filtration and washing (4) consists mainly of urea. The mother liquor is introduced into the device 23 to evaporate water and then heated under reduced pressure to evaporate water. The obtained urea enters the melter 12 urea to re-enter the reaction of thermal decomposition. Thus, the urea can be reused and can be reduced manufacturing costs.

An aqueous solution of alkali added in the vessel 16 for dissolution (5) under option exercise may be an aqueous solution of alkali metal hydroxide or an aqueous solution of a hydroxide of alkaline earth metal, more precisely, an aqueous solution of NaOH, KOH or Ca(OH)2. The aqueous alkaline solution may have a concentration from about 10% to 50%. A device for loading an aqueous solution of alkali can be any. For example, an aqueous alkali solution may be introduced through the external supply line or an aqueous alkali solution, can be directly introduced into the tank for dissolving an aqueous solution of alkali.

The temperature of the vessel 16 for dissolution (5) may be in the range from 50C to 105C, more precisely from 60C to 80C. If the temperature of capacity and 16 for dissolution (5) below 50C, the time of dissolution of the crude crystals biureta in the alkaline solution becomes too large, so that the economic efficiency may decrease. On the other hand, if the temperature of the vessel 16 for dissolution (5) above 105C, biuret may deteriorate.

Biuret obtained with the use of equipment to obtain biureta according to the described variant, does not contain cyanuric acid and has high purity. In addition, biuret can be obtained using simple equipment that can be reduced manufacturing costs.

Apparatus for producing cyanuric acid according to another implementation of the existing invention includes: (1) the urea melter to melt urea; (2) reactor thermal decomposition thermal decomposition of urea by heating; (3) the first crystallizer to obtain a suspension of the crude crystals by adding water to the product obtained in the reactor thermal decomposition and cooling the obtained product; (4) the first step of filtering and washing to obtain crude crystals biureta by filtration and washing the suspension of the crude crystals; (5) capacity for dissolution to dissolve the crude crystals biureta in aqueous alkali solution; (6) the second mold to obtain the Uspenie purified crystals biureta by cooling the dissolved product; (7) the second step for filtering suspensions of purified crystals biureta to obtain purified crystals biureta and mother liquor, and washing the treated crystals biureta; (8) the device of neutralization in order to neutralize the mother liquor obtained from the second device for filtering and washing with acid to precipitate crystals of cyanuric acid to obtain a slurry of crystals of cyanuric acid; and (9) the third step for filtering and washing the slurry of crystals of cyanuric acid to isolate crystals of cyanuric acid.

(8) the acid used for neutralization mother liquor may be an inorganic acid, such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid; or organic acid, such as acetic acid, carbonic acid, formic acid, oxalic acid or benzoic acid. In addition, the acid can be any acid having a pH less than 7.

Step 20 neutralization and the third step 21 and 22 filtering and washing the crystals of cyanuric acid as described above.

Up to this point have been described a method and apparatus for obtaining biureta and method and apparatus for producing cyanuric acid.

In the described in the present invention methods and devices of the crude to Italy biureta dissolved in an aqueous alkali solution and then cooled, to obtain crystals biureta. Therefore, biuret high purity and cyanuric acid of high purity can be obtained easily and in a shorter period of time than when using technology digestion with ammonia.

The present invention will be described hereinafter in detail with reference to examples. These examples are given for illustrative purposes only and do not limit the scope of the present invention.

Examples

Example 1

Urea (production SigmaAldrich Co.) was dissolved in the melt of urea at 140C and then introduced into the reactor thermal decomposition of a certain download speed. The temperature in the reactor thermal decomposition was maintained equal to 160C. the Reactor thermal decomposition reactor was continuous, consisting of three reactors connected in series. Air is fed into the reactor thermal decomposition through the lower part of the reactor in the amount of 1 mol air 1 mol of urea. When the air came out of thermal decomposition reactor, it contains ammonia and unreacted isocyanato acid. Exhaust air was applied to the melt of urea to unreacted solanova acid is reacted with urea. The product obtained in the reactor thermal decomposition of continuously fed into the cooling tank to precipitate the crude Krista the crystals biureta. The average residence time of the product in the cooling tank is regulated so that it was approximately 150 minutes. The product obtained in the reactor thermal decomposition, was selected to measure the degree of conversion of urea. As a result, the degree of conversion of urea was approximately 35%. The reaction product of thermal decomposition was identified by liquid chromatography. Per 100 mass parts introduced into the urea reactor, the number biureta was 29.8 mass parts of urea 50.9 mass parts, cyanuric acid 3.0 mass parts and triuret 1.3 mass parts. Thus, the total mass biureta, urea, cyanuric acid and triuret was 85 mass parts. So, minus the total mass of the products obtained from 100 mass parts introduced urea obtained loss of 15 mass parts, that due to the fact that unreacted solanova acid and ammonia were removed from the reactor thermal decomposition. In the future, the amount of each component was measured in the mass parts per 100 mass parts introduced urea.

Water in the amount of 85 mass parts was added to 85 mass parts of the product of thermal decomposition and cooled to 15C. under stirring, then the reaction product was obezvozhivani by centrifugation. Obesogenic the cake, containing the crystals was washed with 15 mass parts of water to remove any remaining urea. As a result, the amount of precipitate obtained was 28 mass parts. Dewatered sludge was analyzed by liquid chromatography. The result found that the number biureta was 85.7 wt.%, the quantity of urea 1.8 wt.%, the amount of cyanuric acid 8.9 wt.% and the number of triuret 3.6 wt.%. In addition, the mother liquor obtained after removal of water, was also investigated by liquid chromatography. Found that the number biureta 4.1 wt.%, urea 35.5 wt.%, cyanuric acid 0.3 wt.%, triuret 0.2 wt.% and water 59.9 wt.%. The mother liquor obtained after removal of water, was heated at a temperature of 110-130C under a pressure of 200 mm Hg and then re-introduced into the melt of urea. The composition of the solution was set prior to its re-introduction into the melt of urea. The number biureta was 12.2 wt.%, urea 86.5 wt.%, cyanuric acid 0.9 wt.% and triuret 0.4 wt.%. Then urea was added to the melt of urea. In the process, the composition of the products of thermal decomposition conversion biureta was increased to equilibrium. In equilibrium the composition of thermal decomposition product was as follows: 37.3 wt.% biureta, 57 wt.% urea, 4.2 wt.% cyanuric acid and 1.5 m is C.% of triuret.

Next to the dehydrated precipitate the crude biureta were added 72 mass parts of water, and then there were added 2.5 mol aqueous solution of NaOH 1 mol cyanuric acid and heated to 70C for 20 minutes for thermal decomposition of the completely reacted. When cyanuric acid is reacted with an aqueous NaOH solution with the formation of salts of cyanuric acid is very soluble in water. The solution obtained by the interaction with the aqueous NaOH solution was introduced into the cooling tank and cooled to 10C. this was accompanied by crystallization and biuret precipitated. The resulting mixture dehydrational using a centrifuge and washed with water to obtain purified biureta. The result was obtained biuret with a purity of at least 99.5 wt.%.

Then dehydrated mother liquor was introduced into the neutralization tank and to it was added HCl to achieve a pH in the neutralization tank is 4. This has precipitated cyanuric acid. The resulting mixture dehydrational at 50C and washed with water to obtain purified cyanuric acid. Obtained in this way cyanuric acid had a purity of 99 wt.%.

Comparative Example 1

122 mass parts of water and 28.6 mass parts of ammonia (19%ammonia water were added to 85 mass parts of untreated sludge biuret is, the resulting processes of thermal decomposition, cooling and filtering according to Example 1 and mixed. The resulting solution was heated to a temperature from 90C to 100C and left for 30 minutes, then cooled to 50C., the pressure in the reactor was gradually reduced to atmospheric to precipitate crystals biureta. When cyanuric acid is formed a compound with ammonia and was soluble in water. As a consequence, the cyanuric acid is not precipitated. The resulting suspension was filtered, the precipitate washed with water from the mother liquor and dried. The dried product is identified by liquid chromatography. As a result, the number biureta was 98%, urea 0.5%, cyanuric acid 0.3% and triuret 1.2%.

In the methods and devices according to the present invention the crude crystals biureta, obtained by thermal decomposition of urea, dissolved in an aqueous alkali solution. Accordingly, compared with the conventional method, methods of obtaining high-purity biureta and high-purity cyanuric acid in accordance with the present invention are simple and inexpensive. Unreacted solanova acid obtained in the process of thermal decomposition, is returned to the urea melter. Urea, obtained after dehydration of match the th solution of the product of thermal decomposition, is returned to the urea melter. Thus, loss of urea can be reduced, and the conversion of urea can be increased, which is effective from the economic point of view. In addition, the ammonia generated in the process, is absorbed in the scrubber and can be reused in other processes.

Although the present invention is discussed and described in detail in the examples, can be made a variety of changes and additions, which is clear and obvious in form and detail without departing from the spirit and scope of the present invention as defined in the following formula.

1. The method of obtaining biureta, including:
(a) melting urea;
(b) carrying out thermal decomposition of molten urea by heating;
(c) adding water to the resulting product of thermal decomposition for the deposition and filtration of the crude crystals biureta;
(d) dissolving the crude crystals biureta in an aqueous solution of alkali;
(e) cooling the dissolved product to precipitate crystals biureta; and
(f) filtering the cooled product to obtain crystals biureta and mother liquor, and washing crystals biureta.

2. The method according to claim 1, wherein in stage (a) urea is heated in the melt to a temperature of from 130 to 160C.

3. The method according to claim 1, wherein in stage (b) temperature is AREVA is in the range from 130 to 200C.

4. The method according to claim 1, in which gaseous ammonia and gaseous isocyanato acid obtained in stage (b) is directed to the step (a).

5. The method according to claim 1, wherein stage (b) is carried out at a flow of air or inert gas in the lower part of the reactor.

6. The method according to claim 1, wherein stage (b) is carried out in a batch reactor or reactor continuous operation, consisting of multiple reactors connected in series.

7. The method according to claim 1, wherein the mother liquor obtained in stage (b), dehydrated and then sent to stage (a).

8. The method according to claim 1, wherein in stage (d) an aqueous alkali solution is an aqueous solution of alkali metal hydroxide or an aqueous solution of hydroxide of alkaline earth metal.

9. The method according to claim 1, wherein in stage (d) the amount of the aqueous alkali solution is from 0.5 to 5 mol per 1 mol of cyanuric acid contained in the crude crystals biureta.

10. The method according to claim 1, wherein in stage (d) an aqueous alkali solution is used at a temperature of from 50 to 105C.

11. The method according to claim 1, wherein in stage (e) dissolved product is cooled to a temperature of from 5 to 40C.

12. The method of obtaining cyanuric acid, including:
(a) melting urea;
(b) carrying out thermal decomposition of molten urea by heating;
(c) EXT is the pressure of water to the resulting product of thermal decomposition for the deposition and filtration of the crude crystals biureta;
(d) dissolving the crude crystals biureta in an aqueous solution of alkali;
(e) cooling the dissolved product to precipitate crystals biureta; and
(f) filtering the cooled product to obtain crystals biureta and mother liquor, and washing crystals biureta.
(g) neutralization using acid filtered mother liquor to precipitate crystals of cyanuric acid to obtain a slurry of crystals of cyanuric acid; and
(h) filtering and washing the slurry of crystals of cyanuric acid for separation of crystals of cyanuric acid.

13. The method according to item 12, in which the acid is an organic acid or inorganic acid.

14. A device for receiving biureta, including:
(1) the urea melter to melt urea;
(2) reactor thermal decomposition in order to decompose the molten urea by heating;
(3) the first crystallizer to obtain a suspension of the crude crystals by adding water to the product obtained in the reactor thermal decomposition, and cooling the resulting solution;
(4) the first step of filtering and washing the crude crystals biureta by filtration and washing the suspension of the crude crystals biureta;
(5) capacity for dissolving the crude crystals biuret is in an aqueous alkali solution;
(6) the second mold to obtain a suspension of purified crystals biureta by cooling the dissolved product; and
(7) second stage filtration and washing to filter the resulting suspension of purified crystals biureta and get the crystals purified biureta and the mother solution, and rinse the cleaned crystals biureta.

15. The device according to 14, further comprising a device for trapping gaseous ammonia and gaseous isocyanates acid, which are formed in the reactor thermal decomposition to return gaseous ammonia and gaseous isocyanato acid in the urea melter.

16. The device according to 14, in which the reactor thermal decomposition is a batch reactor or reactor continuous operation, consisting of multiple reactors connected in series.

17. The device according to 14, further comprising equipment for dewatering the mother liquor obtained in the first device for filtering and washing to re-download dehydrated mother solution in the urea melter.

18. The device 14 in which the aqueous alkali solution is an aqueous solution of alkali metal hydroxide or an aqueous solution of hydroxide of alkaline earth metal.

19. Device to obtain the Yarovoy acid, including:
(1) the urea melter to melt urea;
(2) reactor thermal decomposition in order to decompose the molten urea by heating;
(3) the first crystallizer to obtain a suspension of the crude crystals by adding water to the product obtained in the reactor thermal decomposition, and cooling the resulting solution;
(4) the first step of filtering and washing the crude crystals biureta by filtration and washing the suspension of the crude crystals biureta;
(5) capacity for dissolving the crude crystals biureta in an aqueous solution of alkali;
(6) the second mold to obtain a suspension of purified crystals biureta by cooling the dissolved product; and
(7) second stage filtration and washing to filter the resulting suspension of purified crystals biureta and get the crystals purified biureta and the mother solution, and rinse the cleaned crystals biureta;
(8) a device for neutralization, in order to neutralize the mother liquor obtained after the second filtering and washing device that uses acid to precipitate crystals of cyanuric acid to obtain a slurry of crystals of cyanuric acid; and
(9) the third stage of filtering and washing the slurry of crystals to cyanide the OIC acid, to highlight the crystals of cyanuric acid.



 

Same patents:

FIELD: chemistry of polymers, chemical technology.

SUBSTANCE: invention relates to the improved method for synthesis of melamine adducts with acids of the order: cyanuric, phosphoric, boric acid in the presence of liquid medium that are modifying agents of polymers. Method involves homogenization of melamine and acid powders in a mixer at temperature from 20°C to 80°C and then prepared mixture is subjected for effect by deformation shift at temperature from 20°C to 150°C at the shift rate value 5-400 s-1 and the total deformation shift value from 1.5 x 103 to 2.0 x 105%. The ratio of melamine to acid is from 2:1 to 1:2 preferably. Effect by the deformation shift is carried out in mechanical reactor of auger type. Invention provides simplifying process in synthesis of end substances, significant decreasing consumptions and avoiding pollution of environment.

EFFECT: improved method of synthesis.

2 cl, 10 ex

FIELD: chemical industry; methods and the devices for production of the biuret.

SUBSTANCE: the invention is pertaining to the method of production of biuret and to the device for its realization. The process includes production in the pyrolysis furnace of the biuret and ammonia by the carbamide pyrolysis, purification of the gained biuret in the reactor of the recrystallization, production of the salt of the monohalogenbiuret metal by interaction of the biuret with the compound of the hypohalogen metal or with halogen and the base in the first reactor. Interaction in the second reactor of the produced biuret metal salt with ammonia, including the ammonia produced during the pyrolysis process of carbamide at the molar ratio of the salt of the monohalogenbiuret metal and the total amount of the ammonia making 1:1-1:1000. The separated excess of the ammonia extracted from biuret in the ammonia evaporator is sent to the ammonia concentrator. At that the ammonia concentrator is intended for concentration of the excess of the ammonia and the ammonia produced in the pyrolysis furnace and for delivery of the concentrated ammonia in the second reactor. The technical result of the invention is the development of the economically profitable continuous process with high efficiency and utilization of the easily accessible source product, reduction of the quantity of the by-products.

EFFECT: the invention ensures the development of the economically profitable continuous process with high efficiency and utilization of the easily accessible source product, reduction of the quantity of the by-products.

14 cl, 62 ex, 12 tbl

The invention relates to new chemical compound 1,5-bis-(2-hydroxyethyl)-biuret, or diethanolamine, and method thereof

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing1,1-1,6-hexamethylene-3,3,3',3'-tetrakis(2-oxyethyl)-bis-urea, which can be used in medicine. The method involves reacting 1,6-hexamethylene diisocyanate with diethanolamine in an aqueous medium, where diethanolamine is taken in stoichiometric amount ranging from 1.001 to 1.01 and after synthesis, excess diethanolamine is removed on a cation exchange resin, which is added to the reaction mixture in amount ranging from 5 to 10% of the mass of initial components while stirring until pH of the reaction mixture falls to a value ranging from 7.0 to 7.2.

EFFECT: simplification of the method and increased output of the end product.

1 cl, 3 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: present invention refers to method of producing diarylamine compound of Formulas , including the stage (1) including formula 21 compound tailing to amine of formula 22 with alkali salt or transition metal catalyst added, and the stage (2) group Y removing from produced compound with acid added: , where radical values are those specified in cl. 1 of formula of invention; as well as to compound of formula (A) or , where X1, X2, X3 and X4 are independently chosen from fluorine and chlorine; and R represents H or methyl.

EFFECT: high-yield production of high purity diaryamines.

49 cl, 9 ex

The invention relates to methods for drug substances, namely meta-chlorodiphenylmethane, which is the original domestic anticonvulsants and recommended Farmkomiteta the USSR for medical use as antiepileptic drugs called galadir [1]

The objective of the invention is to increase the output galadima and simplification of the method of its production
The invention relates to a method for cyclohexylamine, which is an intermediate product in the synthesis of the herbicide preparation lenacil"

The invention relates to a new range of clinical compounds and method for their production, namely to poslednym N-benzhydryl-N'-(TRIFLUOROACETYL)ureas of General formula:

< / BR>
where R is ortho, meta, para-bromine

The invention relates to the field of organic chemistry, and in particular to methods of obtaining symmetrical disubstituted ureas

The invention relates to new chemical compound and method of its production, namely N-benzhydryl-N-(TRIFLUOROACETYL) urea of the formula

< / BR>
Chemical compound synthesized for the first time and assigned state registration number N 9973090

FIELD: chemistry.

SUBSTANCE: method involves input of initial material to undergo oxidation, containing the compound to undergo oxidation into the reaction zone of a reactor-type bubble column through several openings for the initial material and a stream of oxidising agent containing molecular oxygen into the reaction zone of the said column through several openings for the oxidising agent, made in the channel of the bubbling chamber for oxidation. Pressure is reduced by a value not more than approximately 0.3 MPa in the said channel. In the second version of the method at least approximately 5 wt % of the said stream of oxidising agent is released from the said channel from top to bottom. The bubble column has a housing which defines the reaction zone which extends along the central axis with maximum diametre (D), the bottom and top levels of which are at maximum distance (L) from each other, and the ratio L:D equals at least approximately 3:1.

EFFECT: efficient and cheap liquid-phase oxidation of compounds.

35 cl, 35 dwg, 13 ex

FIELD: chemistry.

SUBSTANCE: liquid-phase oxidation is carried out in a reactor-type bubble column. In one version, the method involves input of an oxidising agent stream containing molecular oxygen into the reaction zone of the reactor-type bubble column. Input of a stream of initial material containing the compound to undergo oxidation in the said reaction zone with provision for input of not more than approximately 80 wt % of the said compound to undergo oxidation of the said stream of initial material into one vertical quadrant of the reaction zone, determined theoretically using a pair of intersecting vertical planes which divide the said reaction zone into four vertical quadrants of equal volume. Oxidation of at least a portion of the said compound to undergo oxidation in liquid phase of a multiphase reaction medium contained in the said reaction zone. In another version there is provision for input of at least approximately 25 wt % of the said compound to undergo oxidation into the said reaction zone in one or several positions inside and at a distance from the said vertical sidewalls of at least 0.05D, where D is maximum diametre of the said reaction zone. If the compound to undergo oxidation is paraxylene and the oxidation reaction product is crude terephthalic acid (CTA), then that product can be purified and extracted using cheaper methods compared to the one that could have been used if CTA had been obtained using a traditional high-temperature oxidation method.

EFFECT: more efficient reaction at relatively low temperatures.

34 cl, 35 dwg, 6 tbl, 13 ex

FIELD: engines and pumps.

SUBSTANCE: bubbler reactor of cyclohexane oxidation represents four vertically arranged and interjointed sections I, II, III, IV. Each said section consists of single-pass heat exchanger 1 and tubeless shell 2, the former being arranged longitudinally. Said hear exchanger 1 consists of heat-exchange-bubble tubes fitted in two tube sheets 4 and housing 5.

EFFECT: higher yield of high-concentration oxidiser and lower yield of by-products.

8 cl, 8 dwg

Gas-liquid reactor // 2377063

FIELD: chemistry.

SUBSTANCE: invention relates to design of apparatus for chemical processes which take place in gas-liquid media. The device has a vertical circular housing. At the top end of the housing there is a pipe for outlet of reaction products. A liquid reagent inlet pipe and a gaseous reagent inlet pipe are fitted on the lateral wall of the housing. Inside the housing near the bottom end there is a cyclone ejector directed towards the bottom end, where the said cyclone ejector includes a vertical housing pipe which narrows towards the bottom end, a socket piece for inlet of gaseous reagent and a tangential socket piece for inlet of liquid reagent. At the top of the housing pipe of the cyclone ejector there is a set of nozzles which includes one or more supersonic nozzles, which communicate with the collector cavity, for feeding gaseous reagent into the housing pipe. The collector cavity is connected to the socket piece for inlet of gaseous reagent. The tangential socket piece for inlet of liquid reagent is fitted on the housing pipe of the cyclone reactor at the cutoff level of the supersonic socket piece for inlet of gaseous reagent.

EFFECT: increased homogeneity of the reaction mixture due to higher dispersion of reagent particles.

4 dwg

FIELD: oil-and-gas production.

SUBSTANCE: invention can be used for reservoir hydrogen sulfide neutralisation systems, rubbish places, pit gases and biogas production plants, when refined gas is under pressure approximately equal to atmospheric one. Equipment contains tank with absorber 1, gas cleaning with absorber equipment, pumps for absorber circulation 9, 10, air compressor 11, sulphur extraction device 12 and control device 14. The tank with absorber 1 limited with hermetic case with exhausted air nozzle 2 and includes device for absorber regeneration 3, formed with air distributor 3' and walls 4 and 5. The wall 4 stiffly connected to the tank 1 case top part, and the wall 5 executed with gap relatively to the tank 1 case. The gas cleaning with absorber equipment includes two liquid jet injector pumps 6, two columns for gas cleaning 7, equipped with injection nozzles 8 and mist separators 18. The column for gas cleaning 7 bottom part located inside the tank with absorber 1, at that columns for gas cleaning 7 end part executed vertically up bended and connected under air distributor 3'.

EFFECT: gas cleaning efficiency increase, equipment dimensions reduction, production and installation casts cutting, power consumption and maintenance casts cutting.

4 cl, 3 dwg

FIELD: engines and pumps.

SUBSTANCE: heated heavy oil residues are continuously fed through branch pipe 2 to below horizontal separating partition 6. Air is fed through branch pipe 3 and air control valve 15 onto bottom part of housing 1. Aforesaid separating partition 6 fitted inside housing 1 is furnished with regularly spaced holes 7 and sparge tubes representing various-length branch pipes 8 environed by large-diametre cartridges 8 fitted concentrically at the bottom to make an annular gap. The said cartridges have central holes 10 in bottom 11. Right above separating partition 6, additional anti-foaming device 12 is mounted to communicate with inlet of pipeline 14. Aforesaid pipeline communicates top part of cylindrical housing 1 with its lower part where air control valve 15 is fitted.

EFFECT: higher efficiency, better quality of finished products.

4 cl, 3 dwg, 2 tbl

FIELD: process engineering, heat&mass transfer.

SUBSTANCE: gaslift reactor has tight vertical casing 1 accommodates distributors 3 and 4 for intake of chlorine and ethylene, and circulation pipe 2. Ethylene dichloride upflow originates in circular space between reactor casing 1 and circulation pipe 2, while its downflow is brought about in circulation pipe 2. Distributors 10 and 11, intended for introducing chlorine and ethylene into ethylene dichloride downflow, are arranged at the bottom of circulation pipe 2 at 0.3 to 3.0 of its diametre.

EFFECT: intensified mixing of chlorine and heat-and-mass transfer, higher selectivity of 1,2-ethylene dichloride synthesis.

6 cl, 2 dwg

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