Method of obtaining urea and installation for its realisation

FIELD: chemistry.

SUBSTANCE: invention relates to obtaining urea from ammonia and carbon dioxide. As a result of ammonia and carbon dioxide interaction at high pressure in reactor obtained is water solution, which contains urea, ammonium carbamate and ammonia. From obtained water solution carbamate and ammonia are separated by decomposing carbamate and thermal evaporation of ammonia and carbon dioxide in stripping apparatus, obtaining ammonia and carbon dioxide, which after that are again condensed in condenser obtaining carbamate, which is returned to reactor. All stages together with reaction of synthesis are carried out in fact at one and the same pressure. In addition, into reactor additionally supplied is passivating oxygen, obtained as a result of interaction waste gases, which contain carbon dioxide, ammonia and passivating oxygen which did not take part in the reaction, are removed from reactor and are supplied into bottom part of stripping apparatus for passivation of at least part of its internal surfaces. Installation for obtaining urea contains communicating with each other and forming closed high pressure contour reactor, stripping apparatus, condenser, section of final urea purification and pipelines for supply into reactor of carbon dioxide and ammonia. It is equipped with pipeline for supply into reactor of passivating oxygen and pipeline for connecting upper part of reactor with bottom part of stripping apparatus.

EFFECT: ensuring even and efficient passivation of all apparatuses of high pressure contour.

13 cl, 2 dwg

 

The technical field to which the invention relates.

The present invention relates to a method for producing urea from ammonia and carbon dioxide as a result of their interaction at a certain high pressure in the respective reactor for the synthesis of urea. The invention relates in particular to a method of the type specified above, the implementation of which is the reaction product of ammonia and carbon dioxide, which is essentially an aqueous solution containing urea, ammonium carbamate and ammonia, are divided into ammonium carbamate and ammonia, which return to the reactor, and an aqueous solution of urea, from which the subsequent purification receive urea with a minimum number of remaining ammonia and carbon dioxide. More specifically the present invention relates to a method of the type specified above, the implementation of which as a result of decomposition of the carbamate in the corresponding Stripping apparatus by thermal evaporation receive the ammonia and carbon dioxide, which then condense in the corresponding capacitor to obtain a carbamate, which is returned to the reactor, and all of these operations together with the reaction of the synthesis of urea is carried out essentially at the same pressure in a closed path, known as the high pressure circuit (ARC).

The present invention relates also what to install to get the urea proposed in the invention method.

The level of technology

It is known that currently, urea is produced by way of the type specified above, in which the carbamate and ammonia is recovered from the aqueous solution in the so-called ARCS, which consists of a reactor for the synthesis of urea, a Stripping device and the capacitor, which is typically implemented in the form of a tubular heat exchanger. It is also known that high corrosivity involved in the process of obtaining urea liquids and gases and their chemical aggressiveness reduce the service life of the respective devices ARCS.

For this reason, and also with regard to the difficult working conditions in the cell (pressure from 135 to 175 bar, the temperature in the reactor from 180 to 200°C, the temperature in the Stripping apparatus from 170 to 210°C) to further improve the technology of urea significantly depends on the possibility of using special steel grades, metals such as titanium and zirconium, as well as other materials with high corrosion resistance.

For protection made from materials such devices from corrosion and their outer and/or inner walls, which are ARCS in contact with aggressive liquids and/or gases, usually Passepartout.

It is known, in particular, the proposal to use in the synthesis of the urea oxygen and submit to the ARCS in a given volume of air (possibly enriched with oxygen), the which passivates the metal walls of the apparatus.

For this purpose, in particular, the oxygen required for the passivation of the walls of the reactor, is typically added to the composition a certain amount of air fed to the reactor through the bottom part of the carbon dioxide, and rising in the reactor up oxygen passivates the metal surface, with whom he somehow comes into contact.

The majority of the oxygen fed from below into the reactor, and then with a solution of urea is served at the top, above the tube bundle part (head) of the Stripping apparatus. Separated from the urea solution oxygen together with resulting in the Stripping apparatus of the pairs immediately out of the upper part of the Stripping apparatus and may not provide adequate passivation of its internal surfaces. Therefore, a reliable passivation rest of the ARCS in the lower part of the Stripping apparatus is necessary to additionally apply a certain controlled amount of air contained in which oxygen rises to the Stripping apparatus upward, passes through the tube bundle and accordingly passivates the inner surface of the Stripping apparatus.

For all its certain advantages to this method of obtaining urea has certain disadvantages associated with the supply of additional quantity of air in the lower part tparn the machinery.

It is obvious that at high pressure in the Stripping apparatus, reaching 140 bar, serve him only compressed air, using sophisticated equipment, particularly suitable compressor, which consumes a lot of energy and requires additional maintenance costs.

Another disadvantage of such a method of producing urea is associated with the need to use a fairly reliable device for precisely controlling the amount fed in the reactor and in the Stripping apparatus of the air, the excess of which can lead to unpleasant consequences, in particular to the formation of explosive mixtures.

Another disadvantage of this method of producing urea is related to the fact that together with the air, which is fed to the Stripping apparatus in addition to the air supplied into the reactor, in the Stripping apparatus is a significant amount of inert gas, for which the ARC must be extracted from the reaction products by using a separate and complicated separators. Thus, in particular, when the air supply to the reactor and Stripping machine with the source to obtain a urea reagent (ammonia and carbon dioxide) in order to avoid their losses and avoid reducing the total output ARCS, as well as to address environmental problems associated with the possible release into the surrounding atmosphere at existing plants for urea is necessary to use special, quite complex equipment for separation and recovery of ammonia and carbon dioxide from leaving the Stripping apparatus of gases.

Summary of the invention

The present invention was used to develop a new method to produce urea specified in the beginning of the description of a type that would ensure the possibility of effective uniform and cheap passivation apparatus ARCS and simultaneously, the possibility of cost-effective, and address the limitations and/or disadvantages of the known methods.

This problem is solved by using the proposed invention is a method of producing urea from ammonia and carbon dioxide, which is that the result of the interaction of ammonia and carbon dioxide at a certain high pressure in the respective reactor obtain an aqueous solution containing urea, ammonium carbamate and ammonia from aqueous solution produce carbamate and ammonia by decomposition of carbamate and thermal evaporation of ammonia and carbon dioxide in the corresponding Stripping apparatus receives the ammonia and carbon dioxide, which then condense in the corresponding capacitor to obtain a carbamate, which is returned to the reactor, and all these stages together with the reaction the synthesis is carried out on creatures is at the same pressure, and which is characterized by the fact that the rector of the synthesis serves passivating oxygen; from the reactor divert exhaust gases containing unreacted carbon dioxide and ammonia and passivating oxygen withdrawn from the reactor off-gases are served in the lower part of the Stripping apparatus and use them for passivating at least part of its internal surfaces.

Proposed in the invention is a method of obtaining urea can significantly reduce the amount of air supplied to the ARC, and therefore substantially increase the total output ARCS and provides an effective passivation exposed to aggressive (corrosive) liquids and gases of the internal walls of the Stripping apparatus.

Other distinctive features and advantages of the invention is a method of producing urea in more detail below, the example is not limiting, but only to illustrate the invention the preferred option its possible implementation with reference to the accompanying drawings.

Brief description of drawings

Attached to the description of the drawings shows:

figure 1 - installation diagram for obtaining urea proposed in the invention method and

figure 2 - schematic view in enlarged scale of one of the devices of the installation, the scheme of which is shown in Fi is .1.

The preferred embodiment of the invention

Attached to the description of the drawings proposed in the invention, the device for producing urea proposed in the invention method indicated total item 10.

Upon receipt of urea by the method specified in the beginning of the description type urea is produced from ammonia and carbon dioxide, which react at a certain high pressure in the respective reactor 12.

In the reactor 12 by the interaction of ammonia and carbon dioxide receive an aqueous solution containing urea, ammonium carbamate and ammonia.

From the obtained aqueous solution produce carbamate and ammonia by decomposition of carbamate and thermal evaporation of ammonia and carbon dioxide in the corresponding Stripping apparatus 14 receives the ammonia and carbon dioxide, which then condense in the corresponding capacitor 16, receiving the carbamate, which is returned to the reactor 12. All of these stages, including the reaction of the synthesis of urea, carried out essentially at the same high pressure in the high pressure circuit (ARC).

In a preferred embodiment, an aqueous solution containing urea, ammonium carbamate and ammonia, taken from the reactor 12, is fed into the upper part 14a Stripping apparatus 14.

Upon receipt of urea proposed in the invention method, the reaction is PR 12 serves also passivating oxygen, away from the reactor 12 to the exhaust gases containing unreacted carbon dioxide and ammonia and passivating oxygen, and exhaust from the reactor 12 to the exhaust gases are served in the lower part 14b Stripping apparatus 14 for the passivation of its internal metal walls or for passivating at least part of its inner surface.

Passivating oxygen is supplied in the ARCS preferably by adding air fed to the reactor 12 to carbon dioxide, i.e. by feeding air and its oxygen directly into the reactor 12. The amount of air added to the carbon dioxide appropriately regulate in order to avoid feed to the reactor is too large quantities of oxygen, which can lead to undesirable consequences, in particular to the formation in the reactor explosive mixture.

Upon receipt of the urea method, proposed in a preferred embodiment of the invention, the upper part 14a Stripping apparatus 14 divert exhaust gases which contain carbon dioxide, ammonia and passivating oxygen, and direct these gases in the condenser 16 for receiving liquid carbamate and the passivation of the inner metal walls of the capacitor 16 or at least part of the inner surface of the condenser 16.

Below with reference to prilog is administered to the description of the drawings the principal design features of the installation 10, designed for the synthesis of urea from ammonia and carbon dioxide.

The installation 10 comprises communicating with each other and forming a closed loop high pressure (CHP) of the reactor 12 synthesis of urea, a Stripping apparatus 14 and capacitor 16. At this facility, in particular, ammonia is fed into the reactor 12 through the pipeline 2, and carbon dioxide - pipeline 3.

Fed to the reactor 12 through the pipeline 5 passivating oxygen is withdrawn from the reactor through a pipeline 6, which connects the upper part 12A of the reactor 12 with the bottom part 14b Stripping apparatus 14. Passivating oxygen from pipe 5 preferably be submitted in the pipe 3, through which the reactor serves carbon dioxide. Preferably also passivating oxygen feed pipe 5 in a common air.

Taken from the reactor an aqueous solution containing urea, ammonium carbamate and ammonia, serves to line 4 in the upper part 14a Stripping apparatus 14.

Stripping apparatus 14 is essentially composed of a bundle of vertical tubes of the heat exchanger 24, through which one above it in the upper part 14a Stripping apparatus 14 pipe 33 serves taken from the reactor 12 synthesis containing urea, ammonium carbamate and ammonia aqueous solution, which from top to bottom passes through the tubes of the heat exchanger and collects the I in the lower part of the body Stripping apparatus. Withdrawn from the upper part 12A of the reactor 12 exhaust gases containing unreacted carbon dioxide and ammonia and passivating oxygen, is fed through a pipe 34 at the bottom, below the tubular heat exchanger 24 part 14b Stripping apparatus 14, from which they fall into the lower ends of the tubes of the heat exchanger 24.

Figure 2 shows one of the tubes of the heat exchanger 24, indicated by the position 24A, and marked the positions 35 and 36 nozzles, designed respectively for removal of the Stripping apparatus of exhaust gases containing carbon dioxide, ammonia and passivating oxygen, and for the selection of the urea solution with traces of ammonia and carbon dioxide.

In a preferred embodiment, the upper portion 14a Stripping apparatus 14 are connected by a pipe 7 to the condenser 16.

Upon receipt of urea proposed in the invention method, the system 10 operates as follows.

Supplied from the reactor 12 to the Stripping apparatus of an aqueous solution containing urea, ammonium carbamate and ammonia, in the form of a film flowing down the tubes 24A of the heat exchanger 24; withdrawn from the upper part 12A of the reactor and fed to the Stripping apparatus through the pipeline 6 exhaust from the reactor gases containing carbon dioxide, ammonia and passivating oxygen, climb the tubes 24A of the heat exchanger 24 and uniformly affect all under erienne corrosion of internal parts Stripping apparatus 14 (the inner walls of the lower portion 14b of the housing, the inner surface of the tubes 24A and the inner walls of the upper portion 14a of the body). It must be emphasized that since the operating pressure in the reactor 12 is somewhat higher than the pressure in the Stripping device 14 (or rather the slightly higher pressure in the Stripping apparatus 14, which is part of the ARC, in which all units operate essentially at the same pressure)discharged from the reactor exhaust gases get into the Stripping device 14 essentially by gravity without the use of any separate compressor.

Required for evaporation heat is generated by condensation of water vapor, for example, at a pressure of 25 bar, passing through the Stripping apparatus 14 through the annulus of the heat exchanger 24 and outside it heats the tube 24A. Pipelines to supply to the Stripping apparatus of fresh steam and selecting from it spent a couple marked positions 36 and 37, and the nozzle positions 38 and 39.

Taken from the upper part 14a Stripping apparatus 14 gases containing carbon dioxide, ammonia and passivating oxygen tubing 7 served in the condenser 16 for receiving liquid carbamate and the passivation of the inner walls of the capacitor 16.

In the condenser 16 (which is essentially consisting of a tube bundle heat exchanger), in which condensation occurs (essentially the full option, shown in figure 1) is withdrawn from the upper part 14a Stripping apparatus 14 gases and is provided with a certain amount of heat, receive low pressure steam (for example, about 3-5 bar), which is used for purification of urea in cleaning sections behind the ARC.

The level of urea solution in the upper part 12A of the reactor 12 is constantly regulate through conventional and therefore do not require special description built-in pipeline 4 device 4A, which allows you to separate an aqueous solution containing urea, ammonium carbamate and ammonia and fed from the reactor to the upper part 14a Stripping apparatus 14, containing unreacted carbon dioxide and ammonia and passivating oxygen flue gas, which is supplied from the reactor in the lower part 14b Stripping apparatus 14.

In taken from the reactor gases also contain inert gases, in particular hydrogen which enters the reactor 12 along with carbon dioxide from a plant for producing ammonia, which is located prior to the installation of 10 to obtain urea, liquid ammonia and nitrogen contained in the air added to the fed to the reactor 12 to carbon dioxide.

Obtained in the condenser 16, the solution of the carbamate in the pipeline serves 8 to the separator 28. In the separator 28 from a solution of carbamate allocate the largest part of the inert gases and some h is the terrain of oxygen, which pipe 9a serves in the final purification section 32 of urea (the so-called regeneration section or excretion of urea).

Coming out of the separator 28 containing no inert substances, the solution of the carbamate in the pipeline 9 is applied to the ejector 30. Of the ejector 30, through which the reactor serves liquid ammonia, a solution of carbamate together with ammonia enters the reactor 12.

The urea solution, which contains the remains of ammonia and carbon dioxide, from the lower portion 14b Stripping apparatus 14 through the pipe 13 serves in section 32 final purification of urea. Contained in the inert gases oxygen pipeline 9a serves in section 32 and use it as needed for passivation.

Obtained in section 32 of molten urea by pipeline 1 is directed to further processing, for example to install for granulation, and the flow of inert gases together with the remnants of ammonia and carbon dioxide by pipeline 9b sent for processing not shown in the drawings corresponding treatment device. In these devices of the inert gases prior to venting to remove all traces of ammonia and carbon dioxide.

In section 32 in the cleaning process of urea formed the so-called weak solution of carbamate or an aqueous solution of carbamate, which pipe 11 and pipe is the wires 7 is recycled back to the condenser 16 and is used for absorption coming to the condenser of the Stripping apparatus 14 vapors of ammonia and carbon dioxide.

On plants for urea great performance is part of the ARC capacitor 16 preferably in the form of a submerged condenser, known as the "Full Condenser"™heat exchanger, consisting of a bundle of vertical tubes of a certain size to obtain optimal for the formation of urea length of stay in it the solution of the carbamate. Such a capacitor 16 operates as a pre-reactor and dramatically reduces the volume of the main reactor 12.

In the present invention it is also proposed a method of passivating the ARC installation 10 for obtaining urea, which consists of communicating with each other reactor 12 synthesis of urea, a Stripping unit 14 and the capacitor 16. When the passivation ARC unit for production of urea proposed in the invention method serves passivating oxygen in the reactor 12 from the reactor 12 to divert exhaust gases containing unreacted carbon dioxide and ammonia and passivating oxygen, and exhaust gases from the reactor are served in the lower part 14b Stripping apparatus 14 for passivating at least a portion of the inner surfaces of the Stripping apparatus 14.

In the preferred embodiment proposed in the invention method of passivating, in addition, from the upper part 14a of the pair of device 14 divert exhaust gases, contain carbon dioxide, ammonia and passivating oxygen, and withdrawn from the Stripping apparatus of the gases fed into the condenser 16 for receiving liquid carbamate and passivating at least a portion of the inner walls of the condenser 16.

The present invention relates also to the use of exhaust from the reactor 12 installation 10 to obtain a urea exhaust gases containing unreacted carbon dioxide and ammonia and passivating oxygen, for passivating at least the inner surface of the lower part of the Stripping apparatus 14 pestiviruses oxygen, which is fed to the reactor 12.

From the above description clearly follows that proposed in the invention is a method of obtaining urea solves the invention the task and has a number of advantages, the main of which is uniform passivation of all devices ARCS.

In addition, the proposed in the invention method is simple and reliable in its implementation.

Another advantage of the proposed invention a method is associated with obvious at first glance, the possibility of using the predominant part of the oxygen fed to the reactor, for effective passivation Stripping apparatus (as well as behind it devices) and, as a consequence of this is, with significant compared with the known methods of obtaining urea of this type by reducing the flow of oxygen.

In addition, in contrast to known methods of obtaining urea and passivation of the devices ARC proposed in the invention method does not require the use of complex equipment for the separation of inert gases and regeneration or discharge of the gases emitted into the atmosphere of the original reactants.

It is obvious that the experts in this area may, in accordance with the specific requirements to make in the above-described unit for the production of urea, various changes and improvements that do not go beyond the scope of the invention defined by its formula.

1. A method of producing urea from ammonia and carbon dioxide, including the supply of ammonia and carbon dioxide in the reactor and ensuring their interaction at high pressure to obtain an aqueous solution containing urea, ammonium carbamate and ammonia, feeding the resulting aqueous solution in the Stripping apparatus and from this aqueous solution selection carbamate and ammonia by ensuring decomposition of carbamate and thermally evaporated ammonia and carbon dioxide and their subsequent re-condensation in the condenser with getting carbamate, which is returned to the reactor, and is obtained from the Stripping apparatus of the solution, the soda is containing urea, the remains of ammonia and carbon dioxide, which is directed to the section final purification of urea, and all stages of the process is carried out essentially at the same pressure, characterized in that said reactor additionally served passivating oxygen, produced by the interaction of exhaust gases containing entered in the reaction of carbon dioxide, ammonia and passivating oxygen away from the reactor and fed into the lower part of the Stripping apparatus for passivating at least part of its internal surfaces.

2. The method according to claim 1, characterized in that as pestiviruses oxygen use air added to the fed to the reactor to carbon dioxide.

3. The method according to claim 1, characterized in that an aqueous solution containing urea, ammonium carbamate and ammonia, is fed into the upper part of the Stripping apparatus.

4. The method according to claim 1, characterized in that the exhaust gases containing carbon dioxide, ammonia and passivating oxygen away from the upper part of the Stripping apparatus and submit them to the condenser to receive liquid carbamate and passivating at least part of its internal surfaces.

5. Device for producing urea from ammonia and carbon dioxide containing communicating with each other and forming a closed loop high pressure reactor, a Stripping apparatus, to which tensator, section final purification of urea and pipelines to supply to the reactor, carbon dioxide and ammonia, characterized in that it is provided with a pipeline for feeding into the reactor pestiviruses oxygen and a pipeline to connect the upper part of the reactor from the lower part of the Stripping apparatus.

6. Installation according to claim 5, characterized in that the piping for feeding into the reactor pestiviruses oxygen connected with tubing to the feed to the reactor of carbon dioxide.

7. Installation according to claim 6, characterized in that the piping for feeding into the reactor pestiviruses oxygen made with the possibility of air flow.

8. Installation according to claim 5, characterized in that it is provided with a pipeline for feeding in the upper part of the Stripping apparatus of an aqueous solution taken from the reactor, containing urea, ammonium carbamate and ammonia.

9. Installation according to claim 5, characterized in that it is equipped with a pipe connecting the upper part of the Stripping apparatus with condenser.

10. Installation according to claim 5, characterized in that the Stripping apparatus provided with a heat exchanger, consisting of a bundle of vertical tubes to feed their upper ends aqueous solution containing urea, ammonium carbamate and ammonia, taken from the reactor, the lower ends of the tubes made with the possibility of message pipeline to connect the top of the hour and the reactor lower part of the Stripping apparatus.

11. Method of passivating the high pressure circuit unit for production of urea, consisting of interconnected networks reactor, a Stripping apparatus, condenser and partition final purification of urea, including flow in the lower part of the Stripping apparatus containing tail gases entered in the reaction of carbon dioxide, ammonia and passivating oxygen obtained in the method according to claim 1 for passivating at least part of its internal surfaces.

12. The method according to claim 11, characterized in that the exhaust gases containing carbon dioxide, ammonia and passivating oxygen away from the upper part of the Stripping apparatus and submit them to the condenser to receive liquid carbamate and passivating at least part of its internal surfaces.

13. The use of off-gases containing entered in the reaction of carbon dioxide, ammonia and passivating oxygen obtained in the method according to claim 1 for passivating at least a portion of the inner surfaces of the Stripping device setup to obtain the urea according to claim 5.



 

Same patents:

FIELD: chemistry.

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EFFECT: changing production capacity by changing pump parameters, possibility of horizontal assembling, reduced expenses on servicing and increased safety.

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1 cl, 3 ex, 1 tbl

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FIELD: chemical industry; methods and devices for production of carbamide solution.

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4 cl, 1 dwg

The invention relates to improvements in the technology of production of urea from ammonia and carbon dioxide

The invention relates to a method of neutralizing ammonia in installations for the production of urea

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The invention relates to the production of mineral fertilizers, in particular to a method of obtaining crystalline urea, which provides effective environmental clean its use in agriculture, chemical industry, etc

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FIELD: chemistry.

SUBSTANCE: invention relates to production of urea from ammonia and carbon dioxide. A reaction mixture is obtained in a synthesis reactor at given high pressure as a result of a reaction between NH3 and CO2, where the said reaction mixture contains urea, ammonium carbamate and free ammonia in aqueous solution, from which ammonium carbamate and ammonia are extracted and subsequently returned to the synthesis reactor. Ammonium carbamate and ammonia are extracted from the reaction mixture on process steps for decomposing ammonium carbamate to NH3 and CO2 and their stripping and on the next process step for their re-condensation to obtain ammonium carbamate which is returned to the synthesis reactor. The reaction mixture obtained as a result of the reaction between ammonia and carbon dioxide is taken to the process steps for decomposition and stripping using a pump.

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101 cl, 2 ex, 4 tbl, 14 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a method of condensing carbamate through condensation of gaseous phase of carbon dioxide and ammonia into a liquid phase, which is carbamate in aqueous solution and optionally a solution which contains urea and non-reacting substances and liquid ammonia, in a submerged-type condenser, containing a given number of heat-exchange pipes in a bundle, meant for condensing carbamate, into each of which gaseous and liquid phases are fed simultaneously and independently from each other. The invention also relates to a submerged-type device for condensing carbamate.

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14 cl, 4 dwg

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

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11 cl, 2 ex, 2 dwg

FIELD: chemical industry; methods of production of carbamide from carbon dioxide and ammonia.

SUBSTANCE: the invention is pertaining to the method of production of carbamide from carbon dioxide and ammonia. The method of production of carbamide is realized in the reactor of synthesis with the subsequent thermal distillation from the reaction mixture of the carbamate and partially ammonia in the high-pressure apparatus at heat input by means of the steam. The separated gas phase is directed for condensation into the high-pressure condenser, where gas condensation heat is transferred to the heat-carrier with formation of the steam A. The carbamide solution from the high-pressure apparatus is fed for the ammonium carbamate decomposition into the apparatus at the average pressure with usage of the heat carrier. At that as the heat carrier use the steam condensate produced after the high-pressure apparatus in the combination the steam A. The high-pressure condenser represents the submerged condenser. The installation for production of carbamide includes the reactor of the synthesis of carbamide, the high-pressure apparatus for the thermal distillation of the carbamate and ammonia from the solution of synthesis of carbamide with the heat supply by means of the heat carrier, and also contains the apparatus for ammonium carbamate decomposition at the average pressure. As the high-pressure condenser used for the gas phase condensation the installation contains the submerged condenser. The method of the installation upgrade consists that the existing high-pressure condenser is substituted for the submerged condenser. The technical result of the invention is reduction of the power inputs due to upgrade of the equipment and the combined usage of the scheme of recuperation of the heat of the heat carriers.

EFFECT: the invention ensures the reduced power inputs, the upgrade of the equipment, the combined usage of the scheme of recuperation of the heat of the heat carriers.

12 cl, 2 dwg

FIELD: chemical industry; methods of synthesis of carbamide and the column for its realization.

SUBSTANCE: the invention is pertaining to the method of synthesis of carbamide from ammonia and carbon dioxide in the column of synthesis with the gas-liquid recycle, at which the stream of the water solution of the carbon-ammonium salts (CAS) from the area of distilling route from above or from below into the middle of the synthesis column containing the vertical cylindrical body, the corrosion-resistant material lining located on the body interior surface, the mixer and the unions of inlet and outlet of the reactants and having the located inside it perforated pipeline, which holes are disposed in pairs along the pipeline perimeter at the level of the column muddle midpoints of a column at the angle of 20° - 60° to the central axis of the column. The technical result of the invention consists in intensification of the contacting of the introduced components, the increased service life of the column lining layer and the raised conversion due to removal of the surplus of the water formed during the synthesis process.

EFFECT: the invention ensures intensification of the contacting of the introduced components, the increased service life of the column lining layer, the raised of conversion.

3 cl, 3 dwg

FIELD: chemical industry; methods and the devices for production of carbamide from ammonia and carbon dioxide.

SUBSTANCE: the invention is pertaining to the field of chemical industry, in particular, to the methods and the devices for production of carbamide from ammonia and carbon dioxide. The method of production of carbamide includes the interaction of ammonia and carbon dioxide in the zone of synthesis at the heightened temperatures and pressures with formation of the melt of the carbamide containing carbamide, water, ammonium carbamate, ammonia and carbon dioxide. The carbamide melt distillation conduct at the heat feeding on the two stages of pressure preferentially at 15-25°C and 2-5 kgf/cm2. The carbamide melt distillation on the first step of the pressure conduct sequentially in two zones. In the first zone the distillation is conducted adiabatically or at the heat feeding, and in the second zone - at the heat feeding in the stream of carbon dioxide. The condensation-absorption process at refrigeration of the gases of the distillation is conducted with utilization of the aqueous absorbers. The formed aqueous solutions of the carbon- ammonium salts are recycled from the stage of the condensation-absorption of the gases of the distillation of the second step to the stage of the condensation-absorption of the gases of distillation of the first step, and also from the stage of the condensation-absorption of the gases of distillation of the first step into the zone of the synthesis. The evaporation of the aqueous solution of carbamide is exercised in some steps at the heat exchange between the gases of the distillation of the first step and the aqueous solution of carbamide at the stage of the preliminary evaporation. The installation for production of carbamide consists of: the reactor of the carbamide synthesis; the device with the heat feeding from the external source for distillation of the carbamide melt produced in the reactor of the carbamide synthesis at the first step of the pressure and consisting of the column of distillation melt of the first step and the film-type heat exchanger; the device with the heat feeding for the distillation of the carbamide melt on the second step of pressure; apparatuses for evaporation at heating of the aqueous solution of the carbamide produced on the second step of distillation. The devices for condensation-absorption at refrigeration of the gases of the distillation of the both steps switch on the heat exchanger-recuperator for heat interchange between the gases of the distillation of the first step and the aqueous solution of carbamide. The installation also contains a means for feeding of ammonia and carbon dioxide into the reactor of synthesis of carbamide, feeding of the carbamide melt from the reactor of synthesis into the column of distillation of the first step, from the column of distillation of the first step into the film-type heat exchanger and from the film-type heat exchanger into the device for distillation of the second step, the aqueous solution of carbamide from the device for distilling of the second step into the heat exchanger-recuperator and from the heat exchanger-recuperator - into the apparatus for the subsequent evaporation; the gases of distillation from the device for distilling of the first step - in the heat exchanger-recuperator and from the heat exchanger-recuperator - into the device for condensation-absorption of the gases of distillation of the first step; the gases of distillation from the apparatus for distillation of the second step - into the device for condensation-absorption of the gases of distillation of the second step; the solution of the carbon-ammonium salts from the device for condensation-absorption of the gases of distillation of the second step - into the device for condensation-absorption of the gases of distillation of the first step and from the device for condensation-absorption of the gases of distillation of the first step - into the reactor of synthesis, a means for feeding of carbon dioxide into the film-type heat exchanger. The technical result of the invention is the increased degree of the heat recuperation of the production cycle and reduction of he quantity of the heat exchangers using the heating steam from the external sources.

EFFECT: the invention ensures the increased degree of the heat recuperation of the production cycle and reduction of he quantity of the heat exchangers using the heating steam from the external sources.

8 cl, 3 ex, 3 dwg

FIELD: chemical industry; devices and methods of production of carbamate.

SUBSTANCE: the invention is pertaining to the field of chemical industry, in particular, to carbamatecondenserof the sinking type used in the installation for production of the synthesized carbamide from the gaseous carbon dioxide and the liquid ammonia. The condenser (1) of the sinking type contains the bundle (5) of pipes, in which the condensation of the gaseous compounds is exercised and as a result of the interaction of ammonia with carbon dioxide the carbamate is formed. The condenser differs from others by availability the condensate circulating pipe (19, 23) structurally not connected with the bundle (5) of pipes and designed for circulation of the components in the closed contour of the condenser (1)of the part of the condensed inside it gaseous compounds. The availability of the separate circulating pipe structurally not connected with the bundle of the condensation pipes and communicating with the upper and the lower parts of the condenser ensures the possibility of circulation of the carbamate passing over of the bundle of the condensation pipes, what allows to increase essentially the output of carbamate gained as a result of condensation.

EFFECT: the invention allows to raise essentially the output of carbamate gained as a result of condensation.

6 cl, 3 dwg

FIELD: chemical technology.

SUBSTANCE: invention relates to technology for preparing urea. Method involves interaction of pure ammonia and carbon dioxide in reaction space to obtain reaction mixture containing urea, carbamate and free ammonia in an aqueous solution that is treated in evaporator (1) to obtain partially purified mixture that is fed to section for isolation of urea. Diluted solution of carbamate removing from the urea isolating section is subjected for treatment in evaporator (2) and at least part of vapors formed in it is recovered to the reaction space and/or into evaporator (1). Significant part of carbamate in aqueous solution is subjected for decomposition under pressure that corresponds essentially to pressure value in reaction space. Part of decomposition products including ammonia and carbon dioxide in vapor phase is recovered into reactor and/or into the first evaporator (1) and carbamate after its partial decomposing is fed into section for isolating urea. Device for preparing urea consists of the synthesis reactor, evaporators (1) and (2) for partial decomposition of carbamate and for separation of free ammonia and carbon dioxide in vapor phase, apparatus for condensation of vapor flow, pipe-line for recover of carbamate part in aqueous solution into reactor and section for isolation of urea from its aqueous solution. Preferably, pipe-line is fitted with ejector and evaporators are fitted with apparatus for feeding carbon dioxide as a evaporating agent. Invention provides enhancing yield of urea, reducing energy consumptions and investment due to updating the technological schedule of the process.

EFFECT: improved preparing and updating methods.

30 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to production of urea from ammonia and carbon dioxide. A reaction mixture is obtained in a synthesis reactor at given high pressure as a result of a reaction between NH3 and CO2, where the said reaction mixture contains urea, ammonium carbamate and free ammonia in aqueous solution, from which ammonium carbamate and ammonia are extracted and subsequently returned to the synthesis reactor. Ammonium carbamate and ammonia are extracted from the reaction mixture on process steps for decomposing ammonium carbamate to NH3 and CO2 and their stripping and on the next process step for their re-condensation to obtain ammonium carbamate which is returned to the synthesis reactor. The reaction mixture obtained as a result of the reaction between ammonia and carbon dioxide is taken to the process steps for decomposition and stripping using a pump.

EFFECT: changing production capacity by changing pump parameters, possibility of horizontal assembling, reduced expenses on servicing and increased safety.

12 cl, 2 dwg

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

SUBSTANCE: the invention is pertaining to the methods and devices for production of carbamide from ammonia and carbon dioxide. At realization of the method the reaction mixture from the synthesis reactor is fed in the stripper for the partial decomposition of the ammonium carbamate in the flow of the source carbon dioxide at the pressure practically equal to the pressure in the synthesis reactor. The stream of the source carbon dioxide is divided into two parts, one of which is routed into the stripper, and the other part is used as the working stream for injection of the gas stream from the stripper into the vertical condenser. The liquid stream from the stripper is fed at the stage of the subsequent decomposition of the ammonium carbamate, and the gaseous stream from the stripper is injected into the lower part of the vertical condenser for its mixing with source liquid ammonia. The liquid stream from the vertical condenser is fed into the synthesis reactor, butt from the gaseous stream absorb ammonia and carbon dioxide. The installation for production of carbamide consists of: the synthesis reactor; the scrubber for purification of the gaseous streams from the reactor from ammonia and carbon dioxide; the stripper for the partial decomposition of the ammonium carbamate; the vertical condenser, in which the mixing of the gas stream from the stripper with the source liquid ammonia takes place. The stripper is connected to the lines of feeding of the fluid stream from the reactor and the stream of the source carbon dioxide, and also is equipped with tool for injection of the gaseous stream from the stripper into the vertical condenser by the part of the stream of the source carbon dioxide. By the liquid stream the stripper is linked with the apparatuses for the subsequent decomposition of the ammonium carbamate and extraction of carbamide. The method of upgrading of the installation for production of carbamide consists in connection of the reactor of the synthesis to the stripper for the partial decomposition of the ammonium carbamate in the flow of the source carbon dioxide, in equipping the stripper with the tools for injection of the gaseous stream from the stripper into the vertical condenser with the part of the stream of the source carbon dioxide, and also in the availability of the lines of delivery of the gaseous mixture after the injector and the feeding line of the source liquid ammonia into the lower part of the vertical condenser. The technical result of the invention is the increased degree of conversion of the source reagents into carbamide at reduction of the scale of recirculation of the non-converted reactants.

EFFECT: the invention ensures the increased degree of conversion of the source reagents into carbamide at reduction of the scale of recirculation of the non-converted reactants.

11 cl, 2 ex, 2 dwg

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