Method of modernising urea production apparatus

FIELD: chemistry.

SUBSTANCE: invention relates to a method of modernising a urea production apparatus (1) which employs a self-stripping process. The apparatus has high pressure loop which includes at least one synthesis reactor (5) in which ammonia (18) and carbon dioxide (15) are fed as raw material, a stripping section which includes at least thermal stripping column (7), a condensation section which includes at least one carbamate condenser (6) and medium and high pressure equipment for separating carbamate and ammonia. A feed line (18a) is also provided, through which initial carbon dioxide in amount of 20-50% of the entire stream is fed into the stripping section for use as a stripping agent. A urea synthesis apparatus and a urea synthesis method are also disclosed.

EFFECT: invention enables to modernise a urea production apparatus using a cheaper method.

12 cl, 2 dwg

 

The technical field to which the invention relates.

The present invention relates to a method of modernization and the increased capacity of the plant for producing urea, using the process smootharc.

The level of technology

Process smootharc or thermal Stripping method (under the action of high temperatures) is a well known process for the synthesis of urea. Often this process is called process Snamprogetti (Snamprogetti), because it was developed by Snamprogetti in the late 60-ies of the last century. The disclosure of the mentioned technological process and the corresponding installation can be found, for example, in GB 1542371. This process is used on many installations around the world.

Essentially, the process smootharc is a reaction occurring between ammonia and CO2in the reactor under high pressure, approximately 150-160 bar, molar ratio N/C approximately 3.2 to 3.4; the solution containing ammonia and unreacted ammonium carbamate leaving the reactor, is heated in the Stripping column at high pressure, resulting in the decomposition of carbamate with the liberation of ammonia. Formed in the Stripping column vapour phase containing ammonia and CO2, is subjected to condensation in the condenser at high pressure, which, together with the reactor and the OTP is nuclear biological chemical (NBC column, is part of the high pressure circuit, and then sent to re-cycle in the above-mentioned reactor. Typically, the installation also includes a section of decomposition, operating at medium and low pressure, for further separation of urea from unreacted ammonia and carbamate.

The main equipment used at the facility to obtain urea, which is used technological process smootharc are listed below: reactor for synthesis at high pressure that receives the ammonia and carbon dioxide (carbon dioxide), and in which is formed a mixture comprising urea, carbamate and free ammonia in aqueous solution; Stripping section with steam heating, operating at high pressure, which enters the above-mentioned mixture, and in which there is a partial decomposition of carbamate and partial separation of free ammonia, obtaining a vapour phase comprising ammonia and carbon dioxide, and an aqueous solution containing urea and residual carbamate and ammonia; section average pressure, in which the above-mentioned solution containing urea and residual carbamate and ammonia, is heated, resulting in a partial decomposition of the carbamate and the Department of ammonia; section selection operating at low pressure, which of the above section average pressure is the act of urea and residual carbamate, for further decomposition of the carbamate and the separation of residual ammonia; section-condensing, operating at high pressure, comprising at least one horizontal condenser in which the vapor condensation coming from the Stripping section, with the formation of flow of liquid medium containing the return flow of carbamate in aqueous solution, which is fed to the reactor.

Stripping section comprising at least one Stripping tower; the aqueous solution leaving the reactor, is fed into the tube bundle of the column, heated by steam, without additional use odarivaemogo gas. The heat given steam, contributes to the partial decomposition of carbamate with the formation of carbon dioxide and ammonia, which together with part of the free ammonia contained in the above-mentioned mixture is highlighted in the upper part of the Stripping column is condensed in the above-mentioned horizontal condenser, after which it is sent for the second cycle in the reactor. For plants that use process smoothbark, ammonia can also be used as odarivaemogo agent.

The capacitor of the standard installation, which is applied technological process smoothbark, is a horizontal shell-and-tube apparatus evaporative type, in which con is insatia gas phase occurs in the tube space in the presence of a solution of a reflexive carbamate, coming from a section of medium or low pressure and used as a liquid medium of the condensation process. The condensation heat is used to produce steam.

Recently there has been interest in the modernization of existing plants for urea, which is applied technological process smootharc. In the context of this disclosure, the term "modernization" should be understood modification of the existing installation in order to improve its performance and achievements, for example, higher production capacity and(or) a higher degree of chemical transformations, or, for example, in order to reduce energy consumption.

However, the process smootharc has certain disadvantages, which can also have a negative impact on the economic attractiveness upgrading of such facilities. One of the drawbacks is that the efficiency of the process of Stripping under high temperature is not optimal, especially from the point of view of extracting ammonia. Moreover, the significant concentration of ammonia in solution, leaving the Stripping section, increase the load on located further along the technological scheme of the section of medium and low pressure. Such sections of medium and low pressure can be a bottleneck if there is a wish to increase the capacity of the plant.

The method of building power plants for urea using the process smoothbark, disclosed in the publication WO 2006/061083, which has set the goal to the maximum extent possible to avoid replacing expensive equipment, and, among other things, to provide such conditions that at least part of the process stream leaving the reactor, could be subjected to Stripping in carbon dioxide Stripping column in the presence of carbon dioxide as odarivaemogo gas, while increasing productivity by condensing section of the high pressure. In accordance with the disclosure set forth in the publication WO 2006/061083, this means adding carbon dioxide Stripping columns or conversion of existing thermal Stripping columns or ammonium ataboy columns in carbon dioxide Stripping column. Performance by condensation can be increased by adding a scrubber high pressure or the second capacitor operating in series or parallel with the existing capacitor. Alternatively, according to this disclosure, the authors suggest that increased productivity by condensing the existing condenser. To increase the reactivity also propose basin capacitor, the bass the river reactor or a combined reactor.

However, the method described in WO 2006/061083, still expensive, requiring the installation of new equipment (a new carbon dioxide Stripping column and(or) new capacitor), or substantial modification to existing equipment. It should be noted that the Stripping column and the condenser are the most costly items of equipment related to the high pressure circuit.

Summary of the invention

Accordingly, the technical problem underlying the present object of the invention is to further develop a less expensive way to upgrade units for production of urea, using the process smoothbark, of the type discussed above.

In accordance with the present invention, this problem is solved by the way of modernization of the equipment for production of urea, which is used technological process smoothbark, however, this apparatus comprises a reactor for synthesis at high pressure, in which the raw material comes ammonia and carbon dioxide; section thermal Stripping (at high temperatures), operating at high pressure, and partition allocation, including equipment such as medium and low pressure used for separation of carbamate and ammonia, and a condensing section, operating at high the second pressure, comprising at least one shell-and-tube condenser evaporative type, with the distinctive feature of the method is to install a feed line through which, in operation, a small part of the total source of carbon dioxide enters the Stripping section for use as odarivaemogo agent.

The above-mentioned small part of the total source of carbon dioxide ranges from 20 to 50%. In a preferred embodiment of the present invention is about 30% of the original carbon dioxide is sent to a Stripping section, and the remaining approximately 70% in the reactor.

In the first embodiment disclosed by way of implementation of the present invention retain the current shell-and-tube condenser evaporative type. In particular, the existing shell-and-tube condenser evaporative type can be left in order to reduce production costs in the case, if the increase in performance by condensation is not necessary.

In the second variant of the proposed method performance condensing increase by adding at least one capacitor, operating either in parallel or in series with the existing capacitor.

In the third variant of the proposed method original is condensator evaporative type is removed and replaced with a new vertical capacitor submersible type.

In the above-mentioned third embodiment, the way new vertical condenser is placed on a higher elevation than the reactor and Stripping column, in order, if appropriate, to ensure natural circulation by gravity in the high pressure circuit. In this case, the vertical capacitor provide acceptable support structure. In accordance with another preferred embodiment of the present invention, the condenser leave or have almost the same elevation with the reactor; with this arrangement for the feed solution and the condensed return carbamate in the reactor, the pump is used.

In accordance with another variant of the disclosure the present invention provides other means to supply a small portion of the gas phase containing ammonia and carbon dioxide, leaving a section of the Stripping unit directly into the reactor, while the remaining large part of the above-mentioned gas phase is directed to the condensing section.

The present invention has the following advantages. The use of the source of carbon dioxide as odarivaemogo agent, increases the efficiency of the process urethane bog, and this method has demonstrated its effectiveness even without increasing p is poizvoditelnosti by condensation.

In particular, it was found that the efficiency of standard equipment for production of urea, which is used technological process smoothbark, can be unexpectedly increased with lower production costs compared with the costs of technological processes of the prior art requires the addition of new items of equipment, for example, the new Stripping columns and / or condenser.

Adding a new vertical capacitor submersible is another advantage to increase the yield of urea due to chemical conversion of carbamate into urea occurring in the tubes of the condenser. Therefore, the reactivity can be increased without modifying the reactor or adding more expensive United capacitor.

In addition, benefits can be attributed to the fact that when the improved Stripping reduced the content of ammonia in the urea solution coming from the Stripping section; consequently, reduces the load on the subsequent section of the process and there is no need in removing bottlenecks for the entire installation.

It should be noted that it was found that the above-described dividing the total volume of carbon dioxide a small portion of it flowing into the Stripping section, volume, approx the tion, 30%, and the remaining large part directed into the reactor, also, in particular, is an advantage in those variants of implementation of the present invention, in which use existing evaporative condenser type, as well as in those variants, which add a new capacitor or condenser evaporative replace the capacitor submersible type, as described above.

Another object of the present invention is the installation of the synthesis of urea, containing the high pressure circuit, comprising at least one reactor for synthesis, in which the raw material comes ammonia and carbon dioxide; a Stripping section comprising at least one column for Stripping under high temperatures; and a condensing section, comprising at least one urethane capacitor; and further containing equipment for medium and low pressure separation of carbamate and ammonia, characterized by the presence of a feed line through which, in operation, a small part of the total source of carbon dioxide enters the section the Stripping unit for use as odarivaemogo agent.

Another object of the present invention is a method of synthesis of urea on the device for producing urea, using the process smoothbark, which Comte is a high pressure as raw material serves ammonia and carbon dioxide; while the above-mentioned high pressure circuit includes a reactor for synthesis, the Stripping section comprising at least one column for Stripping under high temperatures; the condensing section comprising at least one urethane capacitor, wherein a small part of the total source of carbon dioxide serves in the above-mentioned section of the Stripping unit for use as odarivaemogo agent. The above-mentioned small portion preferably ranges from 20 to 50%, more preferably about 30%.

Additional features and advantages of the present invention will be more apparent from the following description of several examples of its implementation proposed in the present invention, with reference to the accompanying drawings.

Brief description of drawings

In the drawings shown:

figure 1 - simplified outline of the traditional unit for production of urea, which is applied technological process smootharc;

figure 2 - simplified diagram of the setup is depicted in figure 1, enhanced in accordance with one example implementation of the modernization path proposed in this invention.

Detailed description of preferred embodiments of the present invention.

Figure 1 shows the layout of the conventional unit for production of urea, which is applied technological process smootharc or Stripping under high temperatures. This scheme is simplified, and links will be given only to those parts that were useful to understand the essence of the present invention.

Installation 1 includes a section synthesis at high pressure or loop 2 synthesis, working, for example, at a pressure of approximately 150 bar; section 3 process with average pressure at a pressure of 15-25 bar, and section 4 allocation of urea, working at low pressure.

Circuit 2 synthesis includes the reactor 5, a capacitor 6 and a Stripping column 7 running essentially at the same pressure, and the scrubber 8.

The condenser 6 is a horizontal shell-and-tube apparatus evaporative type, input 34 from section average pressure enters the solution of the carbamate in line 29, and the gas phase away from the Stripping column 7, line 32, 33. Condensation occurs in the tube space; the condensation heat is used for steam production.

A Stripping column 7, essentially, is a heat exchanger with tube bundle and steam heated. A solution of carbamate coming from the reactor 5, forms a liquid film inside the tubes of the tube bundle, while the hot steam flowing outside of the tubes, making the AET heat required for decomposition of the carbamate. Ammonia and carbon dioxide are highlighted in the gas phase in the upper part of the Stripping column.

Section 3 processing at an average pressure consists of the node 10, where the decomposition, distillation columns 11 and ammonia condenser, is used to produce ammonia. Division 4 process at low pressure consists of consecutive items of standard equipment and more description in the present disclosure the invention is not given.

Means for supplying different threads to the position of the equipment 1, in General, have numbers from 15 to 36. Such means for feeding can include connecting pipes or pipelines, pumps, compressors, ejectors and other devices known to experts in the art, and therefore their detailed description is not given.

In the present description of the invention, unless otherwise indicated, the terms "feed line" or "line"as a rule, means connecting pipes, pipelines, pumps, compressors, ejectors or other known devices that are acceptable for transporting fluid or gas flow from one area to another.

Standard installation is shown in figure 1, which is applied technological process smooth the RCTs, essentially works as follows. The source of carbon dioxide into the reactor 5 for the synthesis of line 15 and through the compressor 16. After synthesis of liquid ammonia is directed in the same reactor 5 via line 18 when the pump 19 and the heater 20. The ammonia obtained in section 3 low pressure, enters the line 22 for mixing with a source of ammonia. A mixture containing urea, unreacted carbamate and free ammonia, out of the reactor 5 and is supplied to the Stripping column 7, line 23, 24. In the Stripping column 7 is the decomposition solution with formation of a mixture of urea, a certain amount of residual carbamate and ammonia, which is sent to the node 10 of the distillation operating at medium pressure, through line 26, and gaseous ammonia and carbon dioxide in line 32.

At node 10 for decomposition comes another gaseous flow comprising ammonia and carbon dioxide, and an aqueous solution of urea and residual carbamate. Gaseous ammonia and carbon dioxide are mixed with a solution of a reflexive carbamate obtained further technological scheme, in section 3 medium-pressure, and the resulting mixture is fed to the cooling in the heat exchanger 27, and then, after line 28, is sent to distillation column 11. The aqueous solution is subjected to further technological processing in section 3, the middle is the second pressure receiving solution with a low content of carbamate, directed further technological processing in section 4 of low pressure.

Ammonia gas coming out of the distillation column 11, is subjected to condensation, passing through several standard stages of cooling and compression, and then, after line 22, is sent back to the reactor 5 for mixing with a source of ammonia fed to the reactor as raw materials.

A solution of carbamate, obtained in the distillation column 11, using a pump 30 and line 29, sent again in urethane capacitor 6, is mixed with the gas phase at position 33 of equipment, as in the condenser by line 34 receives the mixture of liquid/gaseous media. Gases (except inert) are almost complete condensation in the specified capacitor 6, and a solution of carbamate serves as the liquid medium of the condensation process. The product of the capacitor 6 is the solution of the carbamate in line 35 which is sent back to the reactor 5 through the separator 8 through line 36.

Figure 2 shows the setup diagram 1, modernized in accordance with the first embodiment of the present invention. New line 18a for supplying carbon dioxide is provided to supply a small part of the total amount of carbon dioxide in the Stripping column 7 for use as odarivaemogo agent. In operation, after the mod is ernestii installation part of the carbon dioxide that is sent to the Stripping column 7 through line 18a is a small part of the total number of source CO2preferably component is from 20% to 50%, even more preferably about 30%. The remaining part of the carbon dioxide into the reactor 5 through the existing line 15. In the specified line 15, is directed into the reactor, it is preferable to add the air.

In the mentioned first example of the disclosure the present invention, no further significant modification of the installation 1 is not assumed.

In another example, the disclosure of the present invention (not shown) of the modernization process comprises the further step of adding another capacitor that is installed either sequentially or in parallel with the existing capacitor 6.

In another example, the disclosure of the present invention instead of the horizontal capacitor 6 evaporative provide a new vertical capacitor submersible type, as well as a supply of gaseous ammonia and carbon dioxide from the Stripping columns 7 and mortar return carbamate, change in such a way as to apply them in the pipe above the new capacitor. With all the details and a description of the work of this new capacitor is used instead of the current of the capacitor 6, you can OSN is read in EP-A-1516664. In this example of the invention, the line 33, which was originally directed to the condenser 6 evaporative type (figure 1), subject to modification to its direction in the capacitor submersible type.

In all the above examples, the disclosure of the present invention, the aqueous solution obtained in the cube Stripping columns 7, has a very low content of ammonia, so that the load on the section 3 medium-pressure and, in particular, on the column 11 and ammonia condenser 11a, is significantly reduced. The load on the pump 19 high-pressure ammonia is also reduced. Reducing the load on the section 3 and the pump 19 is an important advantage of the present invention.

In those examples, the disclosure of the present invention, which provide for the installation of a new vertical capacitor submersible type instead of the capacitor 6 evaporative type mentioned new capacitor may be located at a higher elevation than the reactor 5 and the Stripping column 7, to provide a natural circulation by gravity solution of the carbamate from the condenser to the reactor 5 for synthesis and aqueous solution comprising urea, carbamate and free ammonia from the reactor 5 to the Stripping tower 7. In this case, to allow natural circulation, it is preferable that the reactor was operating at the same Yes the tion, that and a Stripping column.

It is also possible to set the above-mentioned new vertical condenser at almost the same elevation as the reactor 5 and a Stripping column 7. It is preferable to provide a pump for supplying the solution of the carbamate of these new condenser to the reactor 5 for synthesis.

It should be noted that chemical conversion of carbamate into urea occurs in the tubes of the condenser submersible type; it was found that the production volume of urea in the standard setting, which is applied technological process smootharc can be increased by approximately PA 30%, thanks to the installation of the above-mentioned capacitor.

1. Upgrade installation (1) to obtain a urea using the process smootharc and containing the high pressure circuit, comprising at least one reactor (5) for the synthesis, in which the raw material comes ammonia (18) and carbon dioxide (15), the Stripping section comprising at least one column (7) for thermal Stripping method, the condensing section comprising at least one urethane condenser (6), and equipment for medium and low pressure separation of carbamate and ammonia, characterized in that provide the feed line (18a), in which from 20 to 50% of the total flux of the source of carbon dioxide will occupait section of the Stripping unit for use as odarivaemogo agent.

2. The method according to claim 1, characterized in that the said part from the source of carbon dioxide, which will be used as odarivaemogo agent is about 30%.

3. The method according to claim 1 or 2, characterized in that impose additional capacitor in parallel or in series with existing condenser (6) mentioned on the installation (1) for urea.

4. The method according to claim 1 or 2, characterized in that the mount (1) to obtain a urea includes horizontal urethane shell-and-tube condenser (6)and the capacitor (6) is replaced by the vertical capacitor submersible type.

5. The method according to claim 4, characterized in that the said vertical capacitor submersible type have higher altitude compared with the existing reactor (5) and a Stripping column (7) installation (1) to obtain a urea so that during operation of the upgraded installation to ensure natural circulation by gravity in the above-mentioned high pressure circuit.

6. The method according to claim 5, characterized in that said capacitor is set at a higher elevation compared with the existing reactor and Stripping column by means of a suitable supporting structure.

7. The method according to claim 4, characterized in that the said vertical capacitor submersible type have p is kerno on the same elevation, as the reactor (5).

8. The method according to claim 7, characterized in that it set the pump for pumping the condensed solution return carbamate from the condenser to the reactor.

9. The method according to any of the preceding paragraphs, characterized in that provide a line for supplying a small part of the gas phase containing ammonia and carbon dioxide, leaving the Stripping section of the mentioned systems (1) directly into the reactor (5).

10. Installation (1) for the synthesis of urea, containing the path (2) high pressure, comprising at least the reactor (5) for the synthesis of taking the raw material ammonia (18) and carbon dioxide (15), the Stripping section comprising at least one column (7) for thermal Stripping method, the condensing section comprising at least one urethane condenser (6), and equipment for medium and low pressure separation of carbamate and ammonia, characterized by the presence of the feed line (18a) for filing, under operating conditions, 20 to 50% of the total flux of the source of carbon dioxide in the mentioned section of the Stripping unit for use as odarivaemogo agent.

11. The method of synthesis of urea at the facility (1) to obtain a urea using the process smoothbark, in the exercise of which serves as raw material ammonia (18) and carbon dioxide (15) in the circuit (2) high Yes the population, containing the reactor (5) for the synthesis, the Stripping section comprising at least one column (7) for thermal Stripping method, and a condensing section, comprising at least one urethane condenser (6), characterized in that 20 to 50% of the total flux of the source of carbon dioxide is sent to a Stripping section for use as odarivaemogo agent.

12. The method according to claim 11, characterized in that the said part of the flow of the source of carbon dioxide is about 30%.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for synthesis of urea from ammonia and carbon dioxide at high pressure and temperature with formation of ammonium carbamate as an intermediate product. The method includes a high pressure synthesis section comprising at least one step for separating unreacted ammonium carbamate from ammonia via stripping decomposition, carried out in a vertical apparatus which is a stripping column. Said step also involves feeding a CO2 stream, heated to temperature 130-230C, into the bottom part of said stripping column, in amount of 1-15 wt % with respect to total weight of fresh CO2, containing a passivating agent, fed into the process. The amount of this agent is such that its equivalent O2 content in moles ranges from 0.05 to 0.8% with respect to the number of moles of CO2 in said stream. Fresh CO2 is compressed in a multiple-stage compressor having intermediate heat-exchange stages. Apparatus for realising the improved urea synthesis method is also provided. The invention enables to optimise the urea synthesis process.

EFFECT: invention enables to optimise the urea synthesis process.

21 cl, 3 dwg, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of modernising a urea production plant (1). The plant includes: a reactor (2) for urea synthesis, means (7, 8) for feeding ammonia and carbon dioxide into said reactor (2) for urea synthesis, an apparatus (3) for desorption with carbon dioxide for treating the reaction mixture from the reactor (2) and containing urea, carbamate and free ammonia in aqueous solution, with partial decomposition of carbamate and partial separation of free ammonia, thus obtaining a stream containing ammonia and carbon dioxide in vapour phase and a stream containing urea and residual carbamate in aqueous solution, a urea extraction section for treating the stream coming out of the desorption apparatus (3) and containing urea and residual carbamate in aqueous solution for separating urea from residual carbamate in aqueous solution, at least one at least one vertical film condensation apparatus (4) for partial condensation of the stream coming out of the desorption apparatus (3) and containing ammonia and carbon dioxide in vapour phase, thus obtaining a liquid stream containing carbamate in aqueous solution and a gaseous stream containing ammonia and carbon dioxide in vapour phase, means (15, 14) for respectively feeding the stream containing carbamate in aqueous solution and the gaseous stream containing ammonia and carbon dioxide in vapour phase into said reactor (2) for urea synthesis. Said at least one condensation apparatus (4) is provided with means for essentially full condensation of at least a portion of the stream coming out of the desorption apparatus (3) and containing ammonia and carbon dioxide in vapour phase to obtain a stream containing urea and carbamate in aqueous solution. The method involves the following stages: providing second desorption apparatus (47), providing means (9) for feeding a first portion of the stream of reaction mixture coming out of the reactor (2) and containing urea, carbamate and free ammonia in aqueous solution into said desorption apparatus (3), providing means (48) for feeding a second portion of the stream of reaction mixture coming out the reactor (2) and containing urea, carbamate and free ammonia in aqueous solution into said second desorption apparatus (47), and providing means (49) for feeding at least a portion of the stream coming out of said second desorption apparatus (47) and containing ammonia and carbon dioxide in vapour phase directly into the synthesis reactor (2). A method of producing urea and a urea production plant are also disclosed.

EFFECT: invention ensures high output of the product with low power consumption.

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FIELD: chemistry.

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FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing urea from ammonia and carbon dioxide. The method comprises the following steps: feeding ammonia and carbon dioxide into a urea synthesis section operating at given high pressure; reaction of ammonia and carbon dioxide in the synthesis section to obtain an aqueous solution containing urea, ammonium carbamate and ammonia; feeding a first portion of said aqueous solution containing urea, ammonium carbamate and ammonia into a processing section operating at given medium pressure to extract ammonium carbamate and ammonia contained in that solution; dissociation of the first portion of said aqueous solution containing urea, ammonium carbamate and ammonia in the processing section to obtain an aqueous solution of urea and a vapour phase containing ammonia, carbon dioxide and water; condensation of said vapour phase containing ammonia, carbon dioxide and water in the processing section to obtain aqueous ammonium carbamate solution; directing the aqueous ammonium carbamate solution to the repeated cycle in the urea synthesis section. The method also involves feeding aqueous solution of urea obtained at the dissociation step in the processing section into a decomposition apparatus located in the urea extraction section and operating at given low pressure; decomposition of aqueous solution of urea in the decomposition apparatus in the urea extraction section to obtain concentrated urea solution and a second vapour phase containing ammonia, carbon dioxide and water; condensation of the second vapour phase in a condenser located in the urea extraction section and linked to said decomposition apparatus to obtain a first recycle aqueous solution of ammonium carbamate; steam stilling the second portion of aqueous solution containing urea, ammonium carbamate and ammonia while heating in a steam stilling unit essentially at the given high pressure to obtain a second aqueous solution of urea and a third vapour phase containing ammonia, carbon dioxide and water, where said heating is carried out via indirect heat exchange with a vapour stream which forms condensed vapour upon condensation; using at least a portion of the condensed vapour as heat carrier for dissociation of the first portion of the aqueous solution containing urea, ammonium carbonate and ammonia in the dissociation unit located in the processing section at medium pressure. The invention also discloses apparatus for producing urea and a method for upgrading existing apparatus for producing urea.

EFFECT: invention increases production capacity of apparatus for producing urea while simultaneously ensuring high degree of conversion of carbon dioxide to urea.

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FIELD: chemistry.

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EFFECT: high reliability of the used equipment.

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EFFECT: method ensures obtaining carbamide, labeled by stable isotope 13C, with high output with sufficient simplicity and manufacturability of method and absence of highly toxic and explosive substances.

4 cl, 2 tbl, 14 ex

FIELD: agriculture.

SUBSTANCE: liquid ammonia and carbon dioxide are fed to a synthesis section (100) and exposed to a reaction in it in order to produce urea. At the same time the synthesis section comprises at least a reactor, a steaming device and a capacitor, which form a high-pressure circuit, and at least some carbon dioxide is sent to the synthesis section (100) in the liquid phase. Also a plant is proposed for production of urea, as well as a method to increase urea production plant efficiency.

EFFECT: increased energy efficiency of urea production method.

13 cl, 7 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to plant intended for producing carbamide from ammonium and carbon dioxide at elevated temperature and pressure. Proposed plant comprises high-pressure section comprising reactor, stripper, condenser and scrubber operated at in face one pressure, liquid ammonium feeder, appliance to feed gaseous and liquid carbon dioxide into high-pressure section, appliances to feed liquid flows from reactor into stripper, from stripper at carbamide and circulated liquid flow extraction stage, from condenser into reactor, from scrubber into condenser, appliances to feed gas flows from reactor into scrubber, from stripper into condenser, appliances to feed circulated liquid flow into scrubber, appliance to mix liquid carbon dioxide with another flow including cylindrical housing with appliances to feed liquid carbon dioxide, another process flow and to discharge mixed flow, as well as tapered nozzle arranged inside said housing and aligned therewith and communicated with liquid carbon dioxide feed appliance. Note here that appliance to mix liquid carbon dioxide with gaseous carbon dioxide comprises gaseous carbon dioxide feed union and variable-section insert made up of tube with convergent inlet section and divergent outer. Note also that said insert is arranged to form annular clearance between housing and insert. Also it's proposed the method of carbamide production.

EFFECT: higher reliability.

2 cl, 2 ex, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to apparatus for producing carbamide from carbon dioxide and liquid ammonia at high pressure and temperature, comprising a carbamide synthesis reactor, a pump for feeding liquid ammonia into the carbamide synthesis reactor, a compressor for feeding gaseous carbon dioxide into the carbamide synthesis reactor, a pump for feeding liquid carbon dioxide into the carbamide synthesis reactor, a device for bringing into contact carbon dioxide streams, characterised by that the device for bringing into contact carbon dioxide streams has a cylindrical housing with nozzles for inlet of liquid carbon dioxide, inlet of gaseous carbon dioxide and outlet of the mixed gaseous stream of carbon dioxide, as well as the following, arranged in series inside the housing and coaxial with the housing: a convergent nozzle connected to the liquid carbon dioxide inlet nozzle, and a variable cross-section insert in form of a pipe, the inlet part of which is convergent and the outlet part divergent, where the insert lies in such a way that an annular slit forms between itself and the housing. The invention also relates to a method of producing carbamide using the described device.

EFFECT: use of the present invention simplifies process design, reduces materials consumption of the equipment used and increases reliability of the equipment used.

2 cl, 3 ex, 2 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

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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