Method of decomposing aqueous carbamate solution leaving urea recovery section of urea manufacture plant

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 technical field to which the invention relates.

The present invention relates to the production of urea. In particular, the invention relates to a method of decomposition of an aqueous solution of carbamate which emerges from the section selection urea unit for production of urea. This aqueous solution of the carbamate in the future is also referred to as "recycle solution of carbamate".

Background of invention

Currently, there are a lot of ways to obtain urea based essentially on hold in the reaction space or in the reactor the reaction of interaction between supplied to him by the ammonia and carbon dioxide and the selection of the output from the reaction space of the urea solution contained unreacted substances, particularly ammonia, carbon dioxide and carbamate in aqueous solution, which is then fed back into the reaction space.

To obtain the urea in this way, in the device for producing urea for the reaction space set working with the same, as in the reaction space of the pressure apparatus for the decomposition of carbamate, in which the appropriate treatment, leaving the reaction space of the urea solution there is a partial decomposition of carbamate and partial separation of rest the RA of free ammonia. In the apparatus for the decomposition of carbamate get ammonia and carbon dioxide in the vapor phase stream, which is recycled back into the reaction space, and containing urea and residual carbamate in aqueous solution stream.

The device for producing urea there is also a section excretion of urea, in which the result of separation from the urea remaining carbamate get carbamate in aqueous solution, which is recycled back into the reaction space.

Apparatus for the decomposition of carbamate usually performed in the form of a heat exchanger with a bundle of vertical tubes. The decomposition of the carbamate in such apparatus is the result of heating of the urea solution flowing down in the form of a film on the inner surface of the pipe corresponding to the fluid coolant, in particular water vapor, which heats the pipe. As a result of such heating of the urea solution evaporated (by the method of thermal evaporation) of unreacted ammonia and carbon dioxide.

Upon evaporation of the carbon dioxide to decompose the carbamate using a gas stream containing fresh carbon dioxide, which is passed upward through the said pipe.

Upon receipt of urea by the method proposed in EP-A-0796244, conduct additional partial decomposition obtained in section excretion of urea in the aqueous solution of carbamate, which is then recycled back into the reaction space.

With this additional partial decomposition of an aqueous solution of carbamate significantly reduced the number of returned into the reaction space of water, increases the conversion output and increases the performance of the entire plant for producing urea.

When implementing such a method of producing urea on the device for producing urea use a separate apparatus intended for the partial decomposition of at least part of the solution of the carbamate coming from sections highlight the urea cycle solution of carbamate), which results from the partial decomposition or evaporation receive an additional stream containing vapors of ammonia and carbon dioxide, which condense and return back into the reaction space.

For all its advantages, this method of producing urea has a certain disadvantage associated with insufficient decomposition of the carbamate in the above-mentioned designated for this device.

According to the results in the creation of the present invention studies it has been unexpectedly found that the pipes of the apparatus intended for the decomposition of carbamate, primarily in the upper part of the tube bundle, often there is a gap flowing down Lenka recycle solution of carbamate, which in this case is separated from the inner surface of the pipe. The inner surface of the pipe in such a device is not wetted by the liquid.

The Department of film of a solution of the carbamate from the inner surface of the pipe reduces the efficiency of heat transfer between the film flowing through the pipes of a solution of carbamate and water vapor, heating the pipe. Because of the relatively low efficiency of heat transfer and the efficiency of the evaporation apparatus for the decomposition of the carbamate is lower than expected.

To increase the efficiency of decomposition of the carbamate in these conditions could be due to the increase in size of the apparatus, requiring, as it is obvious that additional investment, in excess of theoretically required.

Summary of the invention

The present invention was based on the goal of improving the efficiency of decomposition of the carbamate in the device for producing urea apparatus for evaporation (decomposition) recycle solution of carbamate.

The basic idea of the present invention, which can solve this problem and improve the effectiveness of devices intended for the cycle decomposition of a solution of carbamate, is not connected with the improvement of the design of such devices, and to improve the known methods of decomposition of reciclados the solution of the carbamate.

To solve the problem posed in the present invention, there is proposed a method of decomposition of an aqueous solution of carbamate coming from sections highlight the urea cycle solution of carbamate), to the distinctive features of claims 1-5 claims.

Usually leaving the section allocation urea concentration of water contained in the recycle solution of carbamate, is from 10 to 70%, and its temperature is in the range from 70°to 120°C.

The present invention allows to significantly increase the efficiency of decomposition of the carbamate through controlled evaporation of a film flowing through the tube bundle recycle solution of the carbamate in the apparatus for the decomposition of the carbamate.

Thus, in particular, it has been unexpectedly found that the Department of film recycle solution of the carbamate from the inner surface of the pipe in a known apparatus for the decomposition of the carbamate is essentially due to excessive and intensive evaporation of a solution of the carbamate in the pipes, especially in their upper part. In other words, it is the excessive evaporation of a solution of carbamate and causes disruption of the normal-mode currents flowing through the pipes down film of liquid.

To reduce the intensity of evaporation of liquids in pipes apparatus for the decomposition of the carbamate in the present invention proposed is carried out to reduce too much for optimal evaporation temperature difference between the working temperature of the heating from the outside of the pipe fluid coolant (usually equal 210° C) and the temperature of the entering pipe recycle solution of carbamate (component usually from 70 to 120°).

Studies have shown that reduction of the above-mentioned temperature difference up to 70°C, preferably up to 40-20°significantly reduces the intensity of what is happening in the apparatus for the decomposition of the carbamate process of evaporation of a solution of carbamate and simultaneously increase the efficiency of decomposition of the carbamate.

Obtained by the invention result is contrary to generally accepted at the present time, the assumption that the decrease in temperature difference between the temperature of the recycle solution of carbamate and an operating temperature heat it from the outside fluid coolant must necessarily lead to a decrease in the efficiency of decomposition of the carbamate to gaseous ammonia and carbon dioxide.

Other distinctive features and advantages of the present invention is described in more detail below by not limiting its scope example, the preferred variants of its implementation with reference to the accompanying drawings.

Brief description of drawings

Attached to the description of the drawings in particular, it is shown:

figure 1 is a diagram of the plant for producing urea, in which the decomposition of a solution of carbamate coming from sections highlight urea, ongoing aetsa proposed in the invention method, and

figure 2 - diagram of apparatus intended for the cycle decomposition of a solution of carbamate proposed in the invention method.

Preferred embodiments of the inventions

Figure 1 position 1 indicated the reaction space, in which the pipe 21 serves essentially pure ammonia and in which high pressure is the synthesis of urea.

Positions 2 and 3 marked the high pressure apparatus, intended for the decomposition of carbamate and position 4 is indicated operating at high pressure to the condenser.

Units 2 and 3 for the decomposition of the carbamate and the capacitor 4 are at the same pressure essentially equal to the pressure in the reaction space 1.

Position 5 marked section excretion of urea.

Position 23 is indicated a pipe through which flows obtained in the reaction space 1, the reaction mixture containing urea and unreacted substances, mainly carbamate and free ammonia in aqueous solution.

Taken from the reaction space through the pipeline 23 liquid reaction mixture enters the apparatus 2, in which the appropriate treatment, there is a partial decomposition of carbamate and partial separation from the reaction mixture contained therein free of ammonia.

The seat is hydrated in the diagram position 2 apparatus for the decomposition of the carbamate is evaporators, where as volatile inert gas is used fed into it through the pipeline 24 source of carbon dioxide.

If the decomposition of the carbamate in the apparatus 2 is effected by heat transfer (thermal evaporation), the fresh carbon dioxide is not fed into the apparatus through the pipeline 24, and serve immediately in the reaction space 1 (shown by broken lines to line 22).

The resulting decomposition of the carbamate stream containing ammonia and carbon dioxide in vapor phase gas and liquid flow, which contains urea and residual carbamate in aqueous solution, out of the apparatus 2 through the pipes 25 and 26, respectively.

The pipe 25 passes to the condenser 4, where the at least partial condensation of ammonia and carbon dioxide in vapor phase to receive the liquid stream containing the carbamate in aqueous solution, and possibly a gas stream containing ammonia and carbon dioxide in vapour phase. Both flow (liquid and gas) pipeline 27 return from the condenser back into the reaction space 1.

A stream containing urea and residual carbamate, the pipe 26 serves indicated in the diagram position 5 section excretion of urea, which consists of several devices, in which after separation of the remaining carb the Mat from urea receive an additional amount of carbamate in aqueous solution.

This additional amount of carbamate in aqueous solution coming out from section 5 allocation of urea through the pipeline 28. In taken from sections highlight the urea aqueous solution of carbamate, the temperature of which lies in the range from 70 to 120°usually contains from 10 to 70% water.

In section 5 allocation of urea have the appropriate apparatus for the granulation, in which the solidification of the molten urea receive the final product taken from her by pipeline 29.

In accordance with a preferred embodiment of the present invention an additional amount of carbamate in aqueous solution, taken from section 5 of excretion of urea through the pipeline 28, pre-heated in a heat exchanger, indicated in the diagram position 6. Heated aqueous solution of carbamate serves indicated in the diagram position 3 apparatus for the decomposition of carbamate, in which, about which more is said below, there is a partial decomposition of the carbamate.

For preheating the solution of the carbamate in the heat exchanger 6 and its thermal decomposition apparatus 3 is preferable from the viewpoint of energy saving use of water vapor, which is formed in the condenser 4 due to the released heat in it.

In the proposed variant of the invention at least part of the image is the existing condenser water vapor in the pipe 32 is passed as an external heat source through the heat exchanger 6, and the pipe 33 through the apparatus 3 for the decomposition of the carbamate.

Received in the apparatus 3 for the decomposition of the carbamate stream of gas containing ammonia and carbon dioxide in vapor phase is withdrawn from it through the pipeline 30, and the aqueous solution remaining carbamate - through the conduit 31.

Resulting from at least partial condensation from the condenser 4 through the pipeline 30 gas stream containing ammonia and carbon dioxide in vapour phase, carbamate in aqueous solution by pipeline 27 is recycled back into the reaction space 1.

Taken from the apparatus for the decomposition of carbamate through the conduit 31 aqueous solution, which contains the remaining carbamate, serves for further processing in section 5 excretion of urea.

Figure 2 shows the diagram of the preferred alternative design of the device 3 for the decomposition of the carbamate, which in accordance with the proposed invention a method is the cycle decomposition of a solution of the carbamate.

The device 3 for the decomposition of the carbamate has the upper zone 36 in which is located a horizontal perforated grating 38, and the lower zone 37 evaporation, which is a bundle of vertical tubes 39.

Pipe 39 outside heated by the flow of a fluid coolant, in particular water vapor, which is supplied to the apparatus for razlozheny the carbamate by pipe 33 to a temperature of about 210-230° C. At this temperature in zone 37 evaporation is maintained at 170-210°C.

In the present embodiment, recycle solution of carbamate flowing through the pipe 28, is preheated in the heat exchanger 6 during indirect heat exchange with water vapor, which enters the heat exchanger through the pipe 32, and warmed served in the upper zone is intended to decompose the carbamate condenser 3.

Leaving section 5 highlight the urea cycle solution of the carbamate with temperatures ranging from 70 to 120°With a partially heated in the heat exchanger 6 to a temperature of approximately 110-160°C.

Preheated recycle the solution of the carbamate in the pipe 28 serves in a suitable decomposition of the carbamate apparatus 3, in which it passes through located in the upper area 36 of the apparatus perforated grille and under the action of gravity goes down countercurrent to rising up from the zone 37 evaporation gas containing ammonia and carbon dioxide in vapour phase.

Figure 2 flow flowing through the capacitor 3 gas indicated by the letters Fg, and the stream flowing through it, the liquid indicated by the letters Fl.

As a result of interaction with ammonia and carbon dioxide in vapor phase flow of gas recycle the solution of the carbamate in the upper area 6 of the capacitor 3 more heated and enters the zone 37 evaporation apparatus 3 with a temperature of 150-190° C.

Preheated in the upper zone 36 recycle solution of carbamate gets out of it in located in the area of the evaporation pipe 37 39 by which it is in the form of a film flows down under gravity.

During the decomposition of the carbamate proposed in the invention method, the temperature of the recycle solution of the carbamate at the outlet of the upper zone 36 of the apparatus for the decomposition of the carbamate is not much different from the operating temperature of the heat carrier (fed into the apparatus through the pipeline 33), and the difference between the coolant temperature and the temperature of the recycle solution of the carbamate in the zone of evaporation does not exceed 70°preferably ranges from 20 to 40°C.

When such a temperature difference between the evaporation of a solution of the carbamate in the pipes 39, primarily in the upper part of the pipe occurs in a controlled manner and less intensively than when receiving urea by known methods.

Controlled evaporation of a film flowing through the area 37 of the evaporation cycle solution of the carbamate, which eliminates the possibility of rupture, wetting under this regime, evaporation entire inner surface of the pipe 39, provides almost uniform decomposition of the carbamate on the entire length of the pipe.

At the same time increases the efficiency of decomposition of the carbamate in the apparatus 3 and is provided with a high degree of you the population contained in the recycle solution of carbamate and ammonia and carbon dioxide in vapour phase.

It should be noted, as shown in figure 2 diagram only illustrates an example of a possible implementation of the apparatus 3 for the decomposition of the carbamate, which can be used to cycle decomposition of a solution of carbamate proposed in the invention method.

In another embodiment, for this purpose you can use the device without perforated gratings 38 and consisting only of zone 37 evaporation. In this case, the entire stage of preheating cycle solution of the carbamate (before evaporation) must hold in the heat exchanger 6.

In addition, in some cases, you can refuse the use of the heat exchanger 6, pre (before evaporation) fueling cycle solution of the carbamate in the upper zone 36 of the apparatus 3, intended for the decomposition of the carbamate.

In addition to decomposition of the carbamate in the apparatus 3 can also be used a gas stream containing an inert volatile gas carbon dioxide.

1. The method of decomposition of an aqueous solution of carbamate coming from sections highlight the urea unit for production of urea to a specified temperature by indirect heat exchange with a fluid coolant having a different desired temperature, wherein the difference between the temperature of an aqueous solution of carbamate and the temperature of the coolant is reduced to a value n is greater than 70° C.

2. The method according to claim 1, characterized in that the difference between the temperature of an aqueous solution of carbamate and the temperature of the coolant is reduced to a value lying in the range from 20 to 40°C.

3. The method according to claim 1, characterized in that the aqueous solution of carbamate served in the apparatus (3) for the decomposition of the carbamate having at least a zone (37) evaporation, which by indirect heat exchange of an aqueous solution of carbamate with fluid coolant carbamate is subjected to at least partial decomposition of the receiving stream containing ammonia and carbon dioxide in vapour phase.

4. The method according to claim 3, characterized in that the aqueous solution of the carbamate to the decomposition of the carbamate at least in the zone of evaporation (37) is preheated.

5. The method according to claim 4, characterized in that the solution of the carbamate prior to its submission to the apparatus (3) for the decomposition of the carbamate is heated in the heat exchanger (6).

6. The method according to claim 4, characterized in that the solution of the carbamate is heated by heat exchange with the obtained at least in the zone (37) evaporation stream containing ammonia and carbon dioxide in vapour phase.



 

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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

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: 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 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 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; 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 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 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

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.

EFFECT: increased efficiency and output of the method of condensing carbamate in the proposed device.

14 cl, 4 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to corrosionproof fluid flow conducting parts and equipment comprising one or more such parts. Equipment component comprises first fluid corrosionproof flow conducting section that comprises first corrosionproof material and second fluid flow conducting section that comprises second material. First and second sections are, directly or indirectly, have their ends welded together in solid state to make integral fluid flow conducting part. Invention covers also the method of replacing at least one fluid flow conducting equipment part that proposes replacement component comprising first fluid flow conducting section that includes first material and second fluid flow conducting section that includes second material. Second material is, in fact, identical to that of equipment section whereat spare part is to be mounted. First and second sections are, directly or indirectly, have their ends welded together in solid state to make integral fluid flow conducting part. Space part is secured to equipment by flush butt welding of second material of second space part with material being, in fact identical, to that of equipment attachment section.

EFFECT: higher efficiency due to replacement with parts that feature improved corrosion resistance properties.

101 cl, 2 ex, 4 tbl, 14 dwg

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