Method of production of carbamide, the installation for the method realization (versions), method of the installation upgrade (versions)

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

 

This invention relates to a method for producing urea from carbon dioxide and ammonia in a reactor for the synthesis of urea using the method of distillation of urea.

This method is described, for example, in GB-1542371. According to this method, the solution for the synthesis of urea obtained in the reactor for the synthesis of urea, subjected to heat distillation apparatus distillation of high pressure. In the apparatus of the distillation of high pressure karmabad ammonium and the remaining ammonia is removed from the solution for the synthesis of urea by heating. The gaseous products obtained in the process of distillation, is then condensed in the condenser high pressure. Distilled solution for the synthesis of urea is fed into the apparatus, the medium pressure decomposition, where still present in solution, the ammonium carbamate is decomposed to CO2and NH3. The heat necessary for the decomposition of average pressure is provided by the condensation of water vapor, which is formed during the distillation of the solution for the synthesis of urea at high pressure.

High pressure in this description means a pressure of 12.5-20 MPa, the average pressure in this description means a pressure of 1.5 to 5 MPa.

Unexpectedly, it was found that when the above-described method as a condenser high pressure is used immersion condenser, steam And which is formed in condenatoriaoa pressure, has such a temperature and pressure that can be used in combination with the steam condensate to decompose at an average pressure of ammonium carbamate in solution for the synthesis of urea.

Use the combination of the steam condensate and steam And has the advantage that at least part of the steam condensate becomes applicable for other purposes. This is because the steam condensate has a much higher temperature and pressure than is necessary for use in the decomposition under medium pressure. The steam condensate can be used to better effect in any application in the method of producing urea or outside of this method. For example, in the method of producing urea-pressure steam condensate could be brought up to 1.2 MPa then use to drive the vacuum ejector, or to drive the CO2compressor, pumps for pumping NH3or carbamate.

The applied quantity of condensation of steam or vapor And depend on temperature and pressure steam, which is necessary for decomposition under medium pressure. In the decomposition process at an average pressure required for higher temperature and pressure requires a greater amount of condensation of steam, for less than the required temperature and pressure. The amount of steam condensate and steam And also depend on the possible applications of steam condensate in the installation is ke obtain urea or for other purposes. If the steam condensate can be used for various other applications, it is undoubtedly mainly to the amount of steam And was great as possible.

It is preferable to decompose at an average pressure of ammonium carbamate in aqueous solution of urea is used only pairs of A. This is done by use of the immersion condenser, as couples And in most cases has such a temperature and pressure that it can be used to decompose under medium pressure. Thus, the entire steam condensate can be used for other purposes.

Urea can be obtained by introduction of excess ammonia with carbon dioxide in the synthesis zone under suitable pressure (for example, 12-40 MPa) and a suitable temperature (for example, 160-250° (C) obtaining first ammonium carbamate according to the reaction:

2NH3+ CO2→ H2N-CO-ONH4

Subsequent dehydration of the resulting carbamate ammonium leads to the production of urea in accordance with the equation:

H2N-CO-ONH4↔ H2N-CO-NH2+ H2O

The extent to which these reactions proceed to completion depends, among other things, temperature and excess amount of ammonia used. As a product of this reaction will produce a solution consisting mainly of urine the ins, water, unbound ammonia and ammonium carbamate. The ammonium carbamate and ammonia must be removed from the solution and preferably returned to the reaction zone. In addition to the above solution in the reaction zone is formed of a gas mixture consisting of unreacted ammonia and carbon dioxide, and inert gases. Ammonia and carbon dioxide are removed from the gas mixture and preferably returned to the synthesis reactor.

Urea receive, for example, by way of distillation, urea. Under the method of distillation, urea refers to a method of producing urea, in which the decomposition of ammonium carbamate, is not transformed into urea, and usually remove excess ammonia is carried out mainly under pressure, which, essentially, is almost equal to the pressure in the synthesis reactor. This decomposition/destruction is carried out in one or more distillation apparatus located below in the direction of flow of the synthesis reactor, for example, with additional heating. The latter is called thermal distillation. Thermal distillation means that the ammonium carbamate degradable and present ammonia and carbon dioxide are removed from the urea solution exclusively due to the heat. Coming out of the distillation apparatus, the gas stream containing ammonia and carbon dioxide, is condensed in the condenser of the carb is ATA high pressure and is returned to the reactor in the form of a stream containing ammonium carbamate.

In the methods of distillation, urea is typically used two embodiments of the condenser high pressure for condensation eye gases.

In the first embodiment, the gas mixture subject to condensation, optionally in combination with a suitable solvent (for example, a recirculating solution of ammonium carbamate in water) is passed through a vertical pipe with condensed gas mixture, in combination with a solvent or without him, forming the wall of the tube falling film.

In the second embodiment, as described, for example, in GB-1542371, gases subject to condensation, together with the solvent pass through the horizontal pipe, in which the condensation process.

In both these embodiments the cooling is carried out by passing a suitable coolant in the annulus. As the cooler usually is water.

The lack of condensation in one of the above embodiments of the condenser high pressure is that the residence time of fluid in the pipe is small. Due to the short residence time in capacitors according to the above embodiments, the receiving urea difficult.

The third type of capacitor is a so-called immersion condenser. Submersible capacitor is described, e.g. the measures in EP-155735-A1. In immersion condenser gas mixture subject to condensation, is passed through the tube space of the shell-and-tube heat exchanger, through which may be passed through the diluted urethane solution obtained, for example, in the scrubber high pressure. The released heat of solution and condensation is given by the environment, such as water flowing through pipes, which turns into vapor A.

In the plant producing a urea clearance of inert stream of source materials that are not reacted in the reactor and which leave the reactor through the upper part together with the inert gases, is held in the scrubber high pressure. Then inert the thread is deleted. Purification is carried out using diluted urethane stream, which is formed in the partition selection urea.

Submersible capacitor may be placed in horizontal or vertical position. However, particularly advantageous to perform the condensation is the horizontal position of the immersion condenser (also known as capacitive capacitor; see, for example, Nitrogen No. 222, July-August 1996, pp.29-31), since capacitive condenser liquid, as a rule, is in for a much longer period of time compared to capacitors of other types. In the result, in addition to the carb is Atego solution in capacitance capacitor is formed, the excess amount of urea. This urea is returned to the reactor receiving urea together with urethane solution.

An embodiment of a submersible capacitor is a capacitive reactor. This reactor includes a horizontal condensation zone and the heat exchanger, which is designed as an immersion condenser. Part of the gas mixture to be condensation, is passed through the tube space of the shell-and-tube heat exchanger, through which pass the ammonia and diluted urethane solution, and the heat of solution and heat of condensation is given by the medium, usually water, which becomes steam A.

The advantage of capacitive reactor is that the heat exchanger/condenser mounted in the reactor, which allows you to build a plant for urea with lower capital costs. Capacitive reactor described in more detail in U.S. patent No. 5767313. The condensation zone in capacitive reactor has essentially the same advantages as in the submerged condenser. In this zone, condensing urea formation also occurs with a considerable degree already in section condensation, leading to improved heat transfer, and this gives you the opportunity to get in the condensation zone pairs And with such pressure and at such temperature that it can be used at the stage of decomposition under medium pressure.

Tempera is ur steam And is in the range of 150-175° With, preferably 160-170°C. the vapor Pressure And is 0.3-1 MPa, preferably 0.4 to 0.8 MPa, most preferably 0.6 to 0.8 MPa.

The use of submersible capacitor, capacitance of a capacitor or capacitive reactor may in new installations for the production of urea, which uses thermal distillation. However, it is also possible in existing facilities receiving urea, which is a thermal distillation, to replace the existing condenser submerged condenser. This can be done during a planned shutdown. The existing capacitor may also be replaced capacitance capacitor. It is also possible in the existing plant for urea to replace both the reactor and the capacitor of the capacitive reactor.

An example of a method of distillation, urea is the method described in GB-1542371.

In the method of distillation, urea, described in GB-1542371, the Stripping solution for the synthesis of urea at high pressure is carried out using steam with a pressure of 26 atmospheres (2,6 MPa) and a temperature of 225°C. This steam is used to decompose under medium pressure. In this method of steam distillation, obtained by means of the condenser high pressure, is not suitable for the decomposition of average pressure, because the pressure of this steam is only 0,45 MPa and the temperature is 147°C. with Decomposition at the front pressure is held at a pressure of about 1.8 MPa and a temperature of about 155° C.

If the above method is used submersible capacitor can be obtained pairs And with a temperature of 160-170°and a pressure of 0.6-0.8 MPa. Such pairs And suitable for use in the decomposition of the average pressure at a pressure of 1.8 MPa and a temperature of 155°C.

Description 1:

In the synthesis reactor urea 1 at 15 MPa and 190°served With CO2through the pipe 2 by means of the compressor 3 and NH3through the pipe 4 by means of a pump. Before entering the ammonia reactor 1 through the pipe 4 passes through the jet pump 6, in which the pipe 7 enters the recirculated solution of ammonium carbamate. The urea solution leaving the reactor through the pipe 8, is fed to the distillation apparatus high pressure. In the apparatus of the distillation of high-pressure ammonium carbamate and the remaining ammonia is removed from the solution of the synthesis of urea by heating. Ammonia, carbon dioxide and water vapor obtained in the distillation process, is removed from the upper part of the distillation apparatus through the pipe 10 and is served in a submerged condenser high pressure 11, which serves a solution of ammonium carbamate, out of the zone, located at the bottom of the high pressure circuit through the pipe 12, where they exothermically condense. The condensed solution of carbamate is fed through a submerged condenser high pressure 11 through the pipe 13 to the separator 14 in the rotation in the reaction zone.

The heat released in the condenser 11, is used to produce steam And when 0,6-0,8 MPa and 160-170°C. the resulting steam And is necessary for the decomposition of ammonium carbamate in solution synthesis of ammonia at an average pressure of 1.8 MPa and a temperature of 155°C.

Description 2:

In capacitive reactor for the synthesis of urea 1 at 15 MPa and 190°served With CO2through the pipe 2 by means of the compressor 3 and NH3through the pipe 4 by means of a pump. Before entering the ammonia reactor 1 through the pipe 4 passes through the jet pump 6, in which the pipe 12 enters the recirculated solution of ammonium carbamate, out of the zone, located at the bottom of the high pressure circuit. The urea solution leaving the reactor through the pipe 8, is fed to the distillation apparatus high pressure. In the apparatus of the distillation of high-pressure ammonium carbamate and the remaining ammonia is removed from the solution of the synthesis of urea by heating. Ammonia, carbon dioxide and water vapor obtained in the distillation process, is removed from the upper part of the distillation apparatus through the pipe 10 and is served in a capacitive reactor 1. The heat released in the condenser 11, is used to produce steam And when 0,6-0,8 MPa and 160-170°C. the resulting steam And is necessary for the decomposition of ammonium carbamate in solution synthesis of ammonia at an average pressure of 1.8 MPa and the temperature is e 155° C.

1. A method of producing urea from carbon dioxide and ammonia in a reactor for the synthesis of urea, followed by distillation of the carbamate and partial ammonia from the resulting solution synthesis of urea in the office of the high pressure while applying heat using water vapor and the formation of its condensate, the filing of a separate gas phase by condensation in the condenser high pressure, where the heat of condensation of the gas is transferred to the fluid with the formation of water vapor and feeding the urea solution from the high-pressure apparatus for the decomposition of ammonium carbamate in the apparatus at an average pressure using a fluid, characterized in that for the decomposition of average pressure as the coolant using the steam condensate after high-pressure apparatus in combination with water vapor And the condenser high pressure, which is a submerged condenser.

2. The method according to claim 1, characterized in that as condenser high pressure use capacitive capacitor.

3. The method according to claim 1, characterized in that for the decomposition of average pressure is used only pairs of A.

4. The method according to claim 1, characterized in that the condensation at high pressure is held in the capacitive reactor.

5. The method according to any one of claims 1 to 4, characterized in that the pairs And has a temperature of 160-170°C.

6. Pic is b according to any one of claims 1 to 4, characterized in that the pairs And has a pressure of 0.6-0.8 MPa.

7. Method of improving plant production of urea from carbon dioxide and ammonia, is equipped with a reactor for the synthesis of urea, a high-pressure apparatus for thermal removal of the carbamate and ammonia from the solution synthesis, condenser high pressure for condensation of the gas phase, the apparatus for thermal decomposition of ammonium carbamate with an average pressure when used as a coolant vapor and condensate, characterized in that the existing condenser high pressure replace immersion condenser.

8. The method according to claim 7, characterized in that the immersion capacitor is the capacitance of the capacitor.

9. Method of improving plant production of urea, including the method of thermal distillation, a condenser and a reactor receiving urea, characterized in that the existing condenser and the existing reactor receiving the urea is replaced by a capacitive reactor.

10. Device for producing urea from carbon dioxide and ammonia, comprising a reactor for the synthesis of urea and thermal distillation in the high-pressure apparatus for the distillation of carbamate and ammonia from a solution of urea with a supply of heat with the coolant, and containing the condenser high pressure for condensation of the gas phase is, and apparatus for the decomposition of ammonium carbamate with an average pressure, characterized in that as condenser high pressure contains submerged condenser.

11. Installation according to claim 10, characterized in that the immersion capacitor represents the capacitance of the capacitor.

12. Device for producing urea from carbon dioxide and ammonia, comprising a reactor for the synthesis of urea with high-pressure apparatus for thermal removal of the carbamate and ammonia from the solution of the synthesis with a supply of heat with the fluid, and containing a high-pressure apparatus for condensation of the gas phase, as well as apparatus for the decomposition of ammonium carbamate with an average pressure, characterized in that as a reactor for the synthesis of urea and high-pressure apparatus for condensation of the gas phase contains a capacitive reactor.



 

Same patents:

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: chemical technology.

SUBSTANCE: invention relates to producing urea from ammonia and carbon dioxide. Method involves preparing products of reaction in the synthesis zone as a solution containing urea, ammonium carbamate and unreacted ammonia. Part of solution obtained in synthesis of urea (preferably 10-60 wt.-%) is fed from the synthesis zone to additionally assembled zone of treatment under mean pressure at 1-4 MPa wherein gas flow is separated and subjected for absorption with ammonium carbamate solution of low pressure supplying from the section for isolation and treatment of urea. As a variant of method the invention proposes to use the combined reactor in the synthesis zone representing vertically installed or combined reactor. Enhancement of output of existing processes in synthesis of urea is achieved by feeding part of urea solution synthesized in the synthesis reactor to additionally installed zone for treatment of mean pressure including the dissociation zone, desorption zone of mean pressure and the condensation zone of mean pressure. Invention provides enhancement of output of unit for producing urea being without modification of section of high pressure.

EFFECT: improved method for producing urea.

10 cl, 4 dwg

FIELD: industrial inorganic synthesis.

SUBSTANCE: aqueous carbamate solution leaving urea recovery section at a certain temperature is decomposed by indirect heat exchange with flowing heat carrier having specified temperature. Temperature difference between aqueous carbamate solution and heat carrier is thus decreased to a value not exceeding 70°C, preferably to a value within a range of 20-40°C. Aqueous carbamate solution, prior to be fed into decomposition apparatus, is preheated in heat exchanger by stream produced in evaporation zone containing ammonia and carbon dioxide in vapor phase.

EFFECT: increased efficiency of apparatuses designed for decomposition of recycled carbamate solution.

6 cl, 2 dwg

The invention relates to the technology of complex processing of hydrocarbon fuel gases, such as methane and other natural gases, to obtain a synthesized substances

The invention relates to a method for joint production of ammonia and urea on the plant includes a reactor for the synthesis of ammonia synthesis reactor urea and the regeneration section of the urea

The invention relates to a method for producing urea by the interaction of ammonia with carbon dioxide in two reaction zones operating in parallel

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 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: chemical technology.

SUBSTANCE: invention relates to producing urea from ammonia and carbon dioxide. Method involves preparing products of reaction in the synthesis zone as a solution containing urea, ammonium carbamate and unreacted ammonia. Part of solution obtained in synthesis of urea (preferably 10-60 wt.-%) is fed from the synthesis zone to additionally assembled zone of treatment under mean pressure at 1-4 MPa wherein gas flow is separated and subjected for absorption with ammonium carbamate solution of low pressure supplying from the section for isolation and treatment of urea. As a variant of method the invention proposes to use the combined reactor in the synthesis zone representing vertically installed or combined reactor. Enhancement of output of existing processes in synthesis of urea is achieved by feeding part of urea solution synthesized in the synthesis reactor to additionally installed zone for treatment of mean pressure including the dissociation zone, desorption zone of mean pressure and the condensation zone of mean pressure. Invention provides enhancement of output of unit for producing urea being without modification of section of high pressure.

EFFECT: improved method for producing urea.

10 cl, 4 dwg

The invention relates to a method for joint production of ammonia and urea on the plant includes a reactor for the synthesis of ammonia synthesis reactor urea and the regeneration section of the urea

The invention relates to a method for producing urea by the interaction of ammonia with carbon dioxide in two reaction zones operating in parallel

The invention relates to the synthesis of urea from ammonia and carbon dioxide

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

The invention relates to a method for producing urea

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

FIELD: chemical technology.

SUBSTANCE: invention relates to producing urea from ammonia and carbon dioxide. Method involves preparing products of reaction in the synthesis zone as a solution containing urea, ammonium carbamate and unreacted ammonia. Part of solution obtained in synthesis of urea (preferably 10-60 wt.-%) is fed from the synthesis zone to additionally assembled zone of treatment under mean pressure at 1-4 MPa wherein gas flow is separated and subjected for absorption with ammonium carbamate solution of low pressure supplying from the section for isolation and treatment of urea. As a variant of method the invention proposes to use the combined reactor in the synthesis zone representing vertically installed or combined reactor. Enhancement of output of existing processes in synthesis of urea is achieved by feeding part of urea solution synthesized in the synthesis reactor to additionally installed zone for treatment of mean pressure including the dissociation zone, desorption zone of mean pressure and the condensation zone of mean pressure. Invention provides enhancement of output of unit for producing urea being without modification of section of high pressure.

EFFECT: improved method for producing urea.

10 cl, 4 dwg

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