Method of and device for production of urea

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

 

The technical field to which the invention relates.

The present invention relates to a method for producing urea and installation for its implementation. The invention relates to a method of upgrading the existing installation to obtain urea.

The level of technology

In accordance with the prior art urea is obtained by performing the reaction of liquid ammonia and gaseous carbon dioxide (CO2in the reactor high pressure, typically representing a vertical machine stainless steel, containing a number of plates to improve the mixing of the reagents. In the reactor high pressure in the liquid phase in the form of an intermediate product formed ammonium carbamate and the dehydration of the above carbamate ammonium in the liquid phase are urea. Coming out of the reactor product is essentially an aqueous solution containing urea, carbamate and free ammonia.

In General the installation of urea involves the section of the synthesis and extraction section (urea). The extraction section receives a liquid mixture of urea, carbamate, ammonia and water from the section of the synthesis and supply section synthesis of an aqueous solution recycled carbamate and ammonia. On the output side section of the extract may also be provided by the final section is the processing or purification of urea.

On most modern plants for urea use the so-called method with Stripping, designed to extract the maximum amount of carbamate contained in the aqueous solution leaving the reactor high pressure (HP), in the so-called high pressure (i.e. a pressure essentially equal to the operating pressure of the reactor), thus increasing energy efficiency.

Ways with Stripping known for decades and primarily include the method by Stripping carbon dioxide (CO2and the way to Stripping ammonia (or smootharc). For implementing the method with the Stripping section of the synthesis VD includes at least one reactor, one Stripping device and one capacitor.

The method by Stripping with a CO2the ammonium carbamate otparivat from the urea solution with fresh carbon dioxide. Typically, the Stripping is carried out in a vertical tubular heat exchanger with steam heating, in which the decomposition of neprevyshenie carbamate to gaseous ammonia and carbon dioxide, which then recombine in the condenser, receiving liquid carbamate. Liquid carbamate recycle to the reactor. The heat of condensation is also used to produce low pressure steam, which is located downstream of the section to clean the key, thus minimizing energy consumption.

In the way with smootharc Stripping is carried out with gaseous ammonia, formed by thermal dissociation of a solution of the carbamate obtained in the reactor; thus, the reagent (medium) for Stripping is not required, and the source of gaseous carbon dioxide is usually injected directly into the reactor.

Figure 7 presents a simplified schematic of the high pressure circuit for implementing the known method with the Stripping of ammonia (or smootharc).

The circuit VD mainly includes a reactor 10, a Stripping apparatus 11 and shell-and-tube condenser 12. In the reactor 10 is a reaction for the synthesis of urea to form a liquid mixture of urea, carbamate and ammonia, which pipe 20 serves in the Stripping apparatus 11. Stripping apparatus 11 is, for example, a vertical tubular heat exchanger with steam heating current through the pipes above the liquid mixture.

The liquid phase obtained in the Stripping apparatus 11, the pipe 21 serves in section extraction and purification (not shown), while the pair emerging from the Stripping apparatus, the pipe 22 is sent to the condenser 12. Recycle carbamate coming from sections of the extraction, the line 23 is also fed into the condenser 12, and formed in the condenser 12, the liquid containing reci levy carbamate, send in the reactor 10.

On closer examination the liquid obtained in the condenser 12, which contains a number of inert gases, is directed into the separator 13 to remove the above-mentioned inert gases, and the liquid phase piping 24 and 25, respectively, is fed into the ejector 14. In the ejector 14 serves a source of fresh ammonia from pipe 15 to the pipe 26 to direct fresh ammonia and recycled carbamate in the reactor 10.

Carbon dioxide fed into the reactor 10 through the discharge pipe 16 by using a multistage compressor 17, designed to increase the carbon dioxide pressure to the working pressure in the synthesis loop (>100 bar).

According to the above, in the reactor 10 includes a liquid ammonia through the ejector 14 and the pipe 26, while in the same reactor 10 is provided with the input gaseous CO2by means of the compressor 17 and the pipe 16.

On the installation by Stripping using CO2gaseous carbon dioxide is served by a multi-stage compressor is not in the reactor, and in the Stripping apparatus. CO2acts as a means for Stripping, which causes the decomposition of carbamate and partial separation of free ammonia. Gaseous phase coming from the Stripping apparatus is sent to the condenser, in which p is to obtain an aqueous solution and the steam flow, including recycled carbamate, as well as the source of ammonia and carbon dioxide, which is served in the reactor.

In the above-described configuration settings can be made many changes, however, in accordance with the prior art carbon dioxide is always served in the Stripping apparatus or reactor section synthesis in the gaseous state. In other words, in accordance with the prior art should ensure the supply of carbon dioxide gas in the section of the synthesis, i.e. in the Stripping apparatus installation using CO2for bog or in the digester with smootharc.

Disclosure of inventions

The present invention is the problem of increasing the efficiency of the known method and equipment for production of urea. In fact, energy efficiency reduce various devices and / or auxiliary equipment, which consumes electricity, and, in particular, multi-stage compressor for gaseous CO2.

The basic idea underlying the invention is that at least part of the carbon dioxide serves in section synthesis in the liquid phase.

Thus, the above problem is solved by a method of producing urea, the implementation of which liquid ammonia and carbon dioxide enter the section of the synthesis and inter is astout in this section for the formation of urea, characterized in that at least part of the carbon dioxide serves in section synthesis in the liquid phase.

In accordance with the first embodiment of the invention a portion of the carbon dioxide serves in section synthesis in the liquid phase, and the rest of the carbon dioxide serves in the gas phase.

In accordance with the second embodiment of the invention all of the carbon dioxide serves in section synthesis in the liquid phase and the gaseous CO2in section synthesis is not provided. This second variant embodiment of the invention is applicable for a method with smootharc, at which gaseous CO2for Stripping is not required.

Section synthesis unit for production of urea mainly includes at least one reactor, one Stripping device and one capacitor, forming a high pressure circuit. In accordance with the variants of the invention, the liquid CO2served in the reactor and (or) in the condenser above the high pressure section of the synthesis. Liquid CO2preferably fed into the reactor and / or the capacitor, since the above device during operation already contain liquid.

In particular, in accordance with one variant of the invention, the entire liquid CO2is sent to the reactor. In accordance with another variant is the embodiment of the invention, the entire liquid CO 2is supplied to the condenser; in accordance with another embodiment of the invention the liquid CO2partially directed into the reactor and partially into the condenser. In all the above embodiments of the invention are possible additional input gaseous CO2. In the process with smootharc additional input gaseous CO2is optional and is preferably carried out in the reactor; in the process by Stripping with a CO2the gaseous CO2necessary and is carried out in a Stripping machine.

In accordance with another feature of the invention, the supplied liquid carbon dioxide is mixed with at least part of the supplied liquid ammonia; then the resulting mixture was fed into the reactor and / or the condenser section of the synthesis.

The object of the invention is also an installation for producing urea in the above manner, including at least:

section synthesis;

- money supply that provides input of fresh ammonia and the input of fresh carbon dioxide in the above section synthesis;

different above-mentioned feed means, intended for submission to the section of the synthesis of at least part of the carbon dioxide in the liquid phase.

Money supply preferably includes means d is I mix, designed for mixing at least part of the liquid ammonia, liquid carbon dioxide and feed thus obtained mixture in the appropriate device section synthesis.

In a preferred embodiment of the invention the above mentioned means for mixing include the so-called T-shaped faucet or nozzle; the above nozzle preferably has one part with a separate coaxial passages for liquid carbon dioxide and liquid ammonia, and the second part, acting as a zone of mixing of liquid carbon dioxide and ammonia. In particular, this mixer has an internal passage with a narrowing output channel, mainly corresponding tapered portion of the outer passage, providing, thus, the mixing zone with decreasing in the axial direction of the cross section. After the mixing zone in the nozzle part with a constant cross-section and an extending portion for reducing the velocity of fluid flow.

Another object of the invention is a method of increasing the efficiency of the existing plants for urea, characterized in that provide additional tools for submission to the section of the synthesis of at least part of the carbon dioxide in the liquid phase.

In accordance with the first embodiment above is on how the installation by Stripping with a CO 2remodel, keeping the existing means of supplying gaseous CO2in the Stripping apparatus and providing an additional means of supply of liquid carbon dioxide in the reactor and / or the capacitor circuit VD.

In another embodiment, the method of installation smootharc remodel, replacing the existing means of supplying gaseous CO2means feeding the liquid CO2having features of the invention. The latter can be used to feed into the reactor and / or the capacitor in the circuit VD.

Means to supply liquid carbon dioxide used in the implementation of the above method of increasing the efficiency of the existing plants for urea, preferably include the mixer described above. In accordance with the equivalent features of the invention the new supply is provided for supplying liquid carbon dioxide to the reactor and / or the condenser section of the synthesis.

In accordance with essentially the prior art in all the above embodiments of the invention may be provided with appropriate means for liquefying carbon dioxide and its supply pump.

It should also be noted that if necessary, the reaction, Stripping and condensation equally can be implemented in a single device or the parallel in multiple devices.

The present invention has many advantages compared with the prior art.

It was determined that submission to the section of the synthesis of at least part of the carbon dioxide in the liquid state in the process leads to unexpected energy efficiency.

You should pay attention to the fact that the reaction of formation of urea occurs in the liquid phase, containing carbamate. When carrying out the known methods, and the installations of the prior art liquid ammonia and gaseous CO2entering the reactor, namely in the reaction zone within the reactor, mixed with the goal of establishing close contact between the two phases (i.e., between liquid and gas) and provision of mass - and heat transfer between the above-mentioned reagents. However, the yield of the reaction is limited by the rate of mass transfer from the gas phase into the liquid phase, in which reaction takes place.

The present invention overcomes this limitation by filing both reagents ammonia and CO2- in the liquid phase, resulting in the output is no longer limited to misoperations from the gas phase into the liquid phase. In other words, the reagents are mixed in the reaction zone in a more effective manner, providing benefits also from the point of view of the yield of the reaction.

It should also be noted that the energy consumption for megascope is atogo compressor dioxide (required in known installations) is reduced or even absent, as the supply of liquid CO2the pump requires less energy than compressing gaseous CO2. On the installation by Stripping with a CO2the number of compressible gaseous CO2decreases as part of the CO2served in a liquid state; the plant with smootharc the compressor is no longer needed and all input CO2can liquid feeding pump section synthesis. Reducing energy consumption compensates for the additional energy consumption and cost of equipment required for liquefaction and supply CO2a pump.

Additional features and advantages of the present invention will be better understood from the following non-limiting descriptions of the variants of its implementation, is presented with reference to the accompanying drawings on which is shown:

Brief description of drawings

figure 1 is a General block diagram of the plant for producing urea proposed in the invention,

2 and 3 is a simplified schematic of the high pressure circuit installation smootharc to obtain urea in accordance with a variant embodiment of the invention,

4 and 5 is a simplified schematic of the high pressure circuit unit for production of urea using CO2for Stripping unit in accordance with a variant embodiment of the invention,

6 is shown the e in the simplified cross-section view of a nozzle for feeding a mixed stream of liquid ammonia and carbon dioxide in accordance with the preferred embodiment of the invention.

The implementation of the invention

As can be seen from figure 1, the device for producing urea section 100 includes synthesis, working under high pressure section 200 extraction of urea and possibly cleaning section 300. 1 mainly relates to a device for producing urea, for example, smootharc, by Stripping with a CO2or using another method.

In section 100 of synthesis through the inlet pipe 101 serves fresh liquid ammonia and simultaneously through the pipeline 102 - fresh liquid carbon dioxide. If necessary, may be provided with an additional inlet pipe 103 to enter the gaseous CO2for example, if the unit operates according to the method by Stripping with a CO2and section 100 includes a Stripping apparatus, which receives input of gaseous carbon dioxide.

The pipe 102 is connected with the respective means for receiving liquid carbon dioxide, which are essentially known and therefore not described in detail.

Ammonia and carbon dioxide are the reagents for the reaction of receipt of urea, which is carried out in the above section 100 of the synthesis. In section 100 of the synthesis is accomplished aqueous solution containing urea, carbamate and unreacted ammonia, and pipeline 104 serves his section 200 extraction of urea; in section 200 receives the solution, containing recycle carbamate and ammonia, which pipeline 105 recycle in section synthesis.

Section 200 extraction of urea are connected via pressure lines 201, 202 with section 300 of purification, in which the urea, and the solution of carbamate and ammonia is returned to the extraction section. Purified urea U is drained through the pipeline 301.

Sections 200 and 300 are conventional and not essential to the disclosure of the present invention, so will not be described in detail.

As can be seen from figure 2, it shows the main elements of section 100 of the synthesis on the installation smootharc in accordance with the first embodiment of the invention.

The circuit VD mainly includes a reactor 110, a Stripping apparatus 112 and the capacitor 114. Stripping apparatus 112 is, for example, a vertical shell-and-tube heat exchanger with steam heating, whereas the capacitor 114 is horizontal shell-and-tube heat exchanger.

In the reactor 110 receive the solution mainly containing urea, carbamate and unreacted ammonia, and pressure pipe 120 send it from the upper part of the reactor 110 in the Stripping apparatus 112.

Emerging from the Stripping apparatus 112 liquid phase containing carbamate and urea, pressure pipe 121 is directed to the section extraction/purification (not shown). The gaseous phase from the ary apparatus 112 via pipeline 122 serves in the capacitor 114. Coming from partition retrieve recycle carbamate pipeline 123 also serves in the capacitor 114.

The product emerging from the condenser 114, not counting minor amounts of inert gases, is a liquid mixture, which is sent to the separator 116 carbamate (discharge pipe 127) and using the ejector 118 driven by supplying liquid ammonia return to the reactor 110. Inert gases are removed from separator 116 through line 129, and the liquid phase at a pressure pipe 128 is served in the ejector 118, which receives fresh ammonia pipeline 101. Then the stream consisting mainly of fresh ammonia and recycle carbamate, pipeline 126 serves in the reactor 110.

Liquid carbon dioxide is fed into the reactor 110 of the inlet pipe 102 and the pipe 124. Additional discharge pipe 125 supply to the capacitor 114 liquid CO2that pipe in the condenser zone is mixed with the gas phase coming from the Stripping apparatus and recycle carbamate. Thus, the liquid CO2partially fed into the reactor 110 via pipeline 124, and partly in the capacitor 114 through the pipeline 125, located parallel to the pipe 124.

In other embodiments of the invention (not shown) the entire quantity of liquid CO2served either in reactor 110, either the capacitor 114.

In addition, the reactor 110 may provide additional input CO2but in the gas phase. However, for plants with smootharc it is recommended that the entire quantity of carbon dioxide feeding into the reactor and / or capacitor in the liquid phase, as shown in figure 2.

In accordance with the variant shown in figure 3, the portion of the liquid ammonia in the pressure pipe 101A serves to actuate the ejector 118, and another portion of the liquid ammonia in the pressure pipe 101b fed into the mixer 150, in which liquid ammonia is mixed with liquid carbon dioxide from the pipeline 102 and the resulting liquid mixture discharge lines 124 and 125 is sent to the reactor 110 and the capacitor 114. As noted above, in other embodiments, the invention provides for the supply of the mixture obtained in the mixer 150, only in the reactor 110 or only in the capacitor 114; in addition, the reactor 110 may provide additional input gaseous CO2.

Figure 4 shows the application of the present invention for installation by Stripping with a CO2. The circuit VD includes the reactor 130, a Stripping device 132 and shell-and-tube condenser 134.

In the reactor 130 receive a solution containing urea, carbamate and ammonia, and the pipeline 140 served in the Stripping apparatus 132. In the above-mentioned Stripping apparatus 13 to the pressure pipe 103 and with a compressor 137 serves gaseous CO 2which means for Stripping.

Gaseous CO2acts as a means for Stripping, promotes the decomposition of ammonium carbamate. The liquid phase from the Stripping apparatus 132 includes a partially purified urea solution in the pressure pipe 141 is sent to the section extraction/purification, whereas the gas phase pipe 142 is served in the capacitor 134.

Gas from the upper part of the reactor 130 via pipeline 145 serves in the scrubber 136; the gas in the scrubber 136 is subjected to the absorbance of the diluted solution recycle carbamate coming from partition retrieve urea pipeline 149.

The liquid phase from the scrubber 136 is sent to the ejector 135 driven liquid ammonia coming from the pipe 101; coming out of the ejector 135 stream containing fresh source ammonia and recycle carbamate, pressure pipe 146 is sent to the condenser 134.

Liquid and gas phase from the condenser 134 separately fed into the reactor 130 for discharge lines 143 (gas) and 144 (liquid).

In accordance with the variants of the invention, the liquid carbon dioxide is served either in the reactor 130, or the capacitor 134 or in the reactor and the condenser. 4 shows a variant, in the exercise of which discharge lines 147 and 148, respectively, a portion of the liquid CO2served in the reactor 130 and the other portion of the liquid CO 2in the condenser.

As you can see from the options presented on figure 5, in the pipeline for delivery of liquid CO2set the mixer 150, and liquid ammonia discharge lines 101A and 101b are served in the ejector 135 and above the mixer 150. Thus, the portion of the source of liquid ammonia is used to power the ejector, and the other part is mixed with liquid carbon dioxide. The mixture of ammonia and carbon dioxide obtained in the mixer 150, served either in the reactor or capacitor, or in both the reactor and the condenser.

You should pay attention to the fact that 2 and 5 are simplified schematic, so parts and auxiliary devices (e.g. pumps, valves etc), well known to the person skilled in the art are not shown. It should also be noted that the above schemes provide an opportunity for the exercise of many variants, is also well known in the art.

As can be seen from Fig.6, in the preferred embodiment of the invention the mixer 150 is a nozzle that includes an external passage 151 for liquid ammonia and inner coaxial passage 152 for liquid CO2. Liquid ammonia passes into the annular space around the passage 152 and mixes well with liquid CO2coming out of the passage 152. The passage 152 is saumos the output portion 153, the corresponding tapered portion 154 of the outer passage. Tapering portion 154, reducing the cross-section of the nozzle, provides faster liquid flow, and improves the mixing of liquid ammonia and CO2. Thus, between the passages 151 and 152, around and on the side of the output portion 153 of the internal passage, a zone for mixing with decreasing cross-section.

The next part 155 with a constant cross-section is provided to extend thread. For part 155 should be expanding the output part 156, in which the speed of the mixed flow is reduced.

The nozzle 150 may be installed, for example, on the side of the entrance to the reactor 110 and the capacitor 114, so that the mixture of liquid ammonia and CO2served in the above reactor or capacitor.

The present invention is equally applicable to many different plants for urea, including those that may be aligned with the core block diagram figure 1. The invention can also be used to upgrade existing installation to obtain urea, which in addition to the current means supplying gaseous CO2or instead provide a means to supply liquid CO2.

1. A method of producing urea, the implementation of which liquid ammonia and carbon dioxide serves in section (10) synthesis and exposes in her reaction to produce urea, characterized in that section of the synthesis includes at least a reactor, a Stripping device and the capacitor, forming a high pressure circuit, and at least part of the carbon dioxide fed into the section (100) synthesis in the liquid phase.

2. The method according to claim 1, wherein a portion of the carbon dioxide fed into the section (100) synthesis in the liquid phase, and the rest served in the section (100) synthesis in the gas phase.

3. The method according to claim 1, in which the carbon dioxide is fed to the section (100) synthesis in the liquid state.

4. The method according to one of the preceding paragraphs, in which the section (100) synthesis includes the reactor (110, 130), a Stripping device (112, 132) and the condenser (114, 134), and liquid carbon dioxide serves or in the reactor, or to the condenser.

5. The method according to one of claims 1 to 3, in which the section (100) synthesis includes the reactor (110, 130), a Stripping device (112, 132) and the condenser (114, 134), and a portion of the liquid carbon dioxide fed into the reactor and the portion served in the condenser.

6. The method according to claim 1, in which liquid carbon dioxide is mixed with at least part of the liquid ammonia, obtaining a liquid mixture, which is fed to the section (100) synthesis.

7. Device for producing urea by the method according to one of the preceding paragraphs, comprising at least:
section (100) synthesis and
money supply that provides input of fresh ammonia and the input of fresh carbon dioxide in the synthetic section is a,
characterized in that the section (100) synthesis includes at least a reactor, a Stripping device and the capacitor, forming a high pressure circuit, and configured to feed at least part of the fresh carbon dioxide in the liquid phase by a specified means of submission.

8. Installation according to claim 7, further comprising means (150) for mixing, intended for mixing the injected liquid carbon dioxide at least part of the introduced liquid ammonia.

9. Installation according to claim 8, in which the mentioned means for mixing are the nozzle (150), comprising a first part with a separate coaxial passages for liquid carbon dioxide and liquid ammonia, and the second part for mixing, which is mixed with liquid carbon dioxide and ammonia.

10. Installation according to claim 9, in which the nozzle comprises an outer passage and the inner coaxial passage having a tapered outlet section, generally corresponding to a narrowing of the external passage that leads to the formation of the mixing zone with decreasing in the direction of the axis of the transverse cross-section, and the mixing zone in the nozzle part with a constant cross-section and an extending portion for reducing the velocity of flow of the liquid mixture.

11. The way to increase the efficiency of the installation to obtain the urine is ins, representing a setting with smootharc or by Stripping with a CO2that includes at least the section (100) of the synthesis containing the reactor, a Stripping unit and the condenser in the high pressure circuit, connected to the means of supply of ammonia and to the means supplying gaseous carbon dioxide, wherein the using means of supply of liquid carbon dioxide, is connected to a section of the synthesis.

12. The method according to claim 11, characterized in that optionally use the means (150) for mixing, intended for mixing the input of liquid ammonia with the input liquid carbon dioxide and feed the liquid mixture in the section synthesis.

13. The method according to claim 11 or 12, in which the use of supply of liquid carbon dioxide, designed to supply liquid carbon dioxide to the reactor and / or capacitor.



 

Same patents:

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.

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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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