Method of producing urea and apparatus for realising said method

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.

21 cl, 2 dwg

 

The technical field to which the invention relates.

The present invention in its main aspect, relates to a method for producing urea from ammonia and carbon dioxide that reacts at a given high pressure, in the corresponding section of the synthesis.

In particular, the present invention relates to a method of the above-mentioned type, in which the product of the interaction of ammonia/carbon dioxide, consisting mainly of an aqueous solution containing urea, ammonium carbamate and ammonia, is directed to the stage of extraction of the ammonium carbamate and ammonia flowing at high pressure, which then sent back to the section of the synthesis, while an aqueous solution containing urea, refer to the section extraction of urea, operating at a predetermined low pressure, to obtain a urea with the minimum possible residual ammonia and carbon dioxide.

In particular, the present invention relates to a method of the type in question in which the above-mentioned extraction of carbamate and ammonia includes the stages of decomposition of the carbamate and Stripping unit, preferably in the presence of gaseous reactant (in particular CO2)thus obtained with ammonia and carbon dioxide in the corresponding section of the bog, and then re-condensation in the corresponding section of the con is Ansatie mentioned ammonia and carbon dioxide to obtain a carbamate, which again referred to section synthesis; and in which all the above mentioned stages, including the reaction of the synthesis of urea is carried out at essentially the same high pressure (for example, 135-175 bar) closed circuit received in a given field of technology called "high pressure" or "circuit synthesis at high pressure" (path e).

The present invention also relates to an apparatus, which use the above-mentioned method.

Prior art

Methods of obtaining urea for industrial facilities that are subject to the processes of the above-mentioned type are well known.

A well-known need for increased production capacity of such facilities compared to their design capacity, which these units were originally designed to meet the increasing needs in the synthesis of urea.

For this purpose in the art have proposed various ways, providing stage process with an average pressure (10-40 bar) parts of an aqueous solution containing urea coming from the section of the synthesis, to extract the contained ammonium carbamate and ammonia.

In particular, this section of the process at an average pressure includes the step of dissociation, for which sleduet bog, in the presence of CO2, an aqueous solution containing urea, ammonium carbamate and ammonia, and the subsequent stage of condensation thus obtained vapor (ammonia, CO2and water), add a source of ammonia and an aqueous solution of carbamate (carbonate) of section extraction of urea, working at low pressure. An aqueous solution of carbamate, obtained in step condensation with an average pressure, then return back to the synthesis loop at high pressure (path e).

A method of this type is described, for example, in the publication WO-A-02909323 or even in publications NL-A-8900152.

At that time, as these methods allow to perform the above requirement, at least partially, it was found that the methods of obtaining urea above-mentioned type have the disadvantages associated with the need to use additional quantities of the condensation of water required for condensing the original CO2used as odarivaemogo agent at the stage of Stripping with an average pressure, as well as the source of ammonia is added at the stage of condensation under medium pressure.

This need for additional amount of the condensation water has a negative impact on the degree of conversion in the synthesis of urea, and hence on the efficiency of such section, as well as effectivelyverifiable section extraction of urea, working at low pressure.

Summary of the invention

Accordingly, the technical problem underlying the present invention is the development and implementation of a method of producing urea discussed above type, which would guarantee the achievement of the planned high production capacity of the installation with simultaneous high degree of conversion of carbon dioxide to obtain urea, performed a cost-effective way and at low power consumption, as well as overcoming the above mentioned disadvantages known from the prior art.

In accordance with the present invention this problem is solved by a method of producing urea from ammonia and carbon dioxide, comprising the following steps:

the supply of ammonia and carbon dioxide in the section of the synthesis of urea, operating at a predetermined high pressure,

the introduction of ammonia and carbon dioxide in the reaction section synthesis of obtaining an aqueous solution containing urea, ammonium carbamate and ammonia,

submission of the first part of the aqueous solution containing urea, ammonium carbamate and ammonia, in the section process running at a given mean pressure for the extraction of ammonium carbamate and ammonia contained in the solution,

the first exposure is the second part of the above aqueous solution, containing urea, ammonium carbamate and ammonia dissociation in the processing section, obtaining an aqueous solution of urea and a vapor phase containing ammonia, carbon dioxide and water,

exposure specified vapor phase containing ammonia, carbon dioxide and water condensation in the partition process, obtaining an aqueous solution of ammonium carbamate,

the direction of an aqueous solution of ammonium carbamate to repeat the cycle in the above-mentioned section of the synthesis of urea,

characterized in that it also comprises the steps:

submission of an aqueous solution of urea, obtained at the stage of dissociation in the processing section in the apparatus for decomposition, can be found in section extraction of urea, operating at a predetermined low pressure,

exposure of an aqueous solution of urea decomposition apparatus for decomposing under section extraction of urea, obtaining a concentrated solution of urea and a second vapor phase containing ammonia, carbon dioxide and water,

exposure to second vapor phase condensation in the condenser on the mentioned section of the extraction of urea and soobshayem with the above-mentioned apparatus for decomposition, with receipt of the first circulating an aqueous solution of ammonium carbamate,

exposure to the second part of the aqueous solution containing the his urea, the ammonium carbamate and ammonia Stripping with heat in the Stripping node (machine) mainly at a given high pressure, to obtain a second aqueous solution of urea and a third vapor phase containing ammonia, carbon dioxide and water, these heating is provided by indirect heat exchange with a stream of steam, condenses, forms a condensed steam,

using at least part of the condensed steam as a coolant for the implementation of the dissociation of the first part of an aqueous solution containing urea, ammonium carbonate and ammonia, in the above-mentioned site for dissociation under section processing under medium pressure.

Steam used to provide heat (heat input), and the condensed vapor preferably have a temperature between 200 and 235C and a pressure in the range from 15 to 30 bar, in particular between 15 and 20 bar.

Specified at least part of the condensed steam used at the stage of dissociation at an average pressure is preferably from 80 to 100% of the total number of condensed steam obtained in the Stripping node at high pressure due to the indirect heat exchange.

Stage Stripping unit, including heat-mentioned aqueous solution comprising urea, ammonium carbamate and ammonia, in the Stripping node at high pressure p is edocfile is also carried out in the presence of carbon dioxide, served as odarivaemogo agent.

The method according to the present invention preferably includes the following steps:

condensation of the above-mentioned third vapor phase containing ammonia, carbon dioxide and water obtained in the Stripping unit in the condensation unit with said predetermined high pressure, to obtain a second circulating an aqueous solution of ammonium carbamate;

the filing of this second aqueous urea solution obtained in the Stripping unit in the apparatus for the decomposition of the partition extraction of urea, working at low pressure.

In accordance with one example implementation proposed in the present invention a method node condensation at high pressure consists of a capacitor submersible type, and the above-mentioned condensation in said condenser by contacting such third vapor phase with a circulating aqueous solution of ammonium carbamate and, optionally, liquid ammonia, and recovering the heat of condensation obtained by indirect heat exchange to form a pair.

The term "capacitor submersible type" should be understood type of capacitor, made in the form of a heat exchanger with tube bundle, essentially standard, in which the gas phase, subject to condensation, and, optionally, a solution of carbamate and ammonia n is swollen in the tube space, while the means for indirect heat exchange, for example water, flows in the annular space. The heat delivered by the solution as a result of condensation is removed by using the funds flowing in the annular space, which, due to heat transfer into steam.

In accordance with one aspect of the present invention, the steam generated in the above-mentioned condenser on the site of condensation at high pressure, is used in parallel with at least part of the above condensed steam as a coolant for the dissociation of the above-mentioned first part of an aqueous solution containing urea, ammonium carbamate and ammonia, in the above-mentioned node dissociation, in the above-mentioned section of the process under medium pressure.

The above-mentioned steam generated in the condenser on the site of condensation at high pressure, preferably has a temperature in the range of from 135 to 165C. and a pressure in the range from 3 to 7 bar.

The method disclosed in the present invention preferably includes the following steps:

the flow of carbon dioxide in the above-mentioned capacitor, in the above-mentioned section of the extraction of urea;

condensation of the above-mentioned carbon dioxide with the above-mentioned second steam the phase in the condenser, in the above-mentioned section of the extraction of urea, with the receipt of the circulating aqueous solution of ammonium carbamate.

Most successful results were obtained when applying carbon dioxide in an amount of from 1 to 10 mass. % of the total amount of carbon dioxide supplied to the above-mentioned condenser in the above section the extraction of urea.

The above-mentioned first portion of an aqueous solution containing urea, ammonium carbamate and ammonia, directed in the above section of the process operating at medium pressure, is preferably from 10 to 50 wt.% from the above-mentioned aqueous solution comprising urea, ammonium carbamate and ammonia obtained in the above section synthesis.

And, again, it is preferable that the above-mentioned average pressure section of the process is in the range from 10 to 70 bar.

In accordance with a preferred embodiment of the present invention the above-mentioned circulating aqueous solution of ammonium carbamate, obtained in the above-mentioned condenser section of the extraction of urea, working at low pressure, is fed to the above-mentioned step of condensation of the vapor phase containing ammonia, carbon dioxide and water, in the above-mentioned section of the process is the processing under medium pressure.

Due to the above-mentioned step of condensing the vapor phase containing ammonia, carbon dioxide and water, carried out in the above section of the process at an average pressure, achieve a double effect.

Thanks to the method according to the present disclosure of the subject invention, it becomes possible to achieve a high production capacity with high yield, with a significant reduction of energy consumption.

With regard to energy consumption, a significant advantage can be obtained by using at least part of the condensed steam generated by indirect heat exchange in the Stripping node operating at high pressure, for dissociation of parts of an aqueous solution containing urea, ammonium carbamate and ammonia is supplied to the node of dissociation under section processing under medium pressure.

In this regard, it should be noted that the condensed steam, extending from the site of the Stripping unit, operating at high pressure, has a relatively high temperature and pressure (high heat level)to effectively use it as a carrier for the aqueous solution containing urea, carbamate and ammonia, subject to dissociation in the processing section when the average pressure is NII.

Therefore, it is possible to recover a larger part of the heat of the condensed steam, resulting in a significant reduction of the energy consumption required for the synthesis of urea.

Moreover, in accordance with an alternative example of the present disclosure of the subject invention the steam with high temperature and pressure (high heat)generated in the above-mentioned capacitor, can be successfully used, in parallel with a part of the condensed steam generated in the Stripping node at high pressure, to perform phase dissociation in the partition process with an average pressure. Therefore, a high heat content remaining portion of the condensed steam can be effectively used for other purposes, in particular in other sections of the plant for producing urea, ensuring, thus, the benefits of energy recovery and further reduce power consumption,

Thanks proposed in the present invention method, it was found that the amount of condensation water (in absolute value)required to return unreacted ammonia and carbon dioxide in the form of ammonium carbamate back section of the synthesis, will be much less compared to the amount of condensation water (in absolute value), regulatory and legal bases is to make such a return when using other methods, known from the prior art, in which the partition process, operating at medium pressure, serves a source of carbon dioxide and ammonia.

This is because at the same power unit for production of urea, the present invention method, the amount of ammonia and carbon dioxide to be returned to the section of the synthesis in the form of ammonium carbamate, is significantly smaller in comparison with other methods known from the prior art.

From this it follows that there is a significant increase in the degree of conversion in the synthesis of urea, and total output in the circuit e, which means a great advantage from the point of view of increasing production efficiency and reducing energy consumption at the facility, on which is applied the method according to the present disclosure of the subject invention.

In accordance with another aspect of the present invention mentioned above, the technical problem can be solved at the facility, on which is applied the method according to the present disclosure of the subject invention consists of operating at high pressure section of the urea; operating at medium pressure section of the processing of the first part of the urea solution obtained in the above section and synthesis, including cracker (the node for dissociation) and the capacitor; operating at high pressure node Stripping the second part of the solution obtained in the above-mentioned section of the synthesis and operating at low pressure section of the extraction of urea, including apparatus for decomposition and the capacitor; however, the above-mentioned sections are communicated with each other; and wherein said installation includes a connecting pipe between the above dissociation located in the partition process with an average pressure, and the above-mentioned apparatus for decomposition, can be found in section extraction of urea, working at low pressure, as well as those that are listed the installation includes a connecting pipe between the node bog at high pressure and the said dissociation located in the partition process with an average pressure for feeding the condensed steam, the exhaust from this node bog, in the above-mentioned cracker.

In accordance with the present invention a device for producing urea, which applies the above-mentioned method, can be a completely new installation or existing installation, modified in order to build its capacity.

In the last example in accordance with another aspect of the present image is the shadow shows how the reconstruction of the existing equipment for production of urea from ammonia and carbon dioxide, consisting of operating at high pressure section of the urea, operating at high pressure node Stripping the urea solution obtained in the above section synthesis, and operating at low pressure section of the extraction of urea, comprising the apparatus for decomposing and condenser, and these sections are communicated with each other, characterized in that it comprises the following steps:

the presence of operating at medium pressure section of the processing of the first part of the urea solution obtained in the above-mentioned section of the synthesis, including cracker and a capacitor, with the above-mentioned section of the process operating at medium pressure, is connected with the above-mentioned section of the synthesis of urea, working at high pressure, and, accordingly, section extraction of urea, working at low pressure;

the presence of the connecting pipeline between the above-mentioned apparatus of dissociation under section processing at the average pressure and the above-mentioned apparatus for decomposition, can be found in section extraction of urea, working at low pressure; and

the presence of the connecting pipeline between the above node bog at high pressure and the said dissociation located in the partition process operating at medium pressure, for supplying condensed steam coming out of the above-mentioned node bog, in the above-mentioned apparatus dissociation.

Further features and advantages of the method of producing urea in accordance with the present invention will become more apparent from the following description of preferred example of implementation shown in the illustrative and not restrictive purposes, with reference to the accompanying drawings.

Brief description of drawings

Below the invention is described in more detail with reference to the accompanying drawings, on which:

figure 1 schematically shows an installation for producing urea, which is running a method, according to one of embodiments of the present invention;

figure 2 schematically shows a device for producing urea, which is running a method, according to another exemplary embodiment of the present invention.

Detailed description of preferred embodiments of the present invention.

1 shows a device for producing urea, generally designated by the number 10, which executes the method according to one of embodiments of the present invention.

In accordance with the above-mentioned method of producing urea ammonia N and carbon dioxide With served in the appropriate section 11 of synthesis, when the ore, shown in figure 1, the section of the synthesis of urea includes one reactor R.

In particular, according to the above-mentioned example, the ammonia-N into the reactor R through the condenser 12, and carbon dioxide, in turn, is fed to the reactor R through the Stripping tower 13 and capacitor 12.

Section 11 synthesis of (reactor R), condensation unit (condenser 12), a Stripping unit (Stripping column 13), together with the scrubber 14 (a more detailed description will be given below), all operate essentially under the same high pressure, forming, thus, the circuit synthesis at high pressure (path e) according to the proposed in the present invention method.

In the reactor R, or, rather, in section 11 of the synthesis of ammonia and carbon dioxide react with each other at the said predetermined high pressure (for example, in the range from 130 to 170 bar) and high temperature (for example, in the range from 160 to 200C). From the reactor R goes aqueous solution containing urea, ammonium carbamate and ammonia.

An aqueous solution containing urea, ammonium carbamate and ammonia coming out of the reactor R, is subjected to partial decompression, essentially, in a standard way, for example by means of the valve 15, and hereinafter referred to section 16 of technological processing of such aqueous solution, operating at a given mean pressure, for example, within about is 10 to 70 bar, preferably in the range from 15 to 25 bar and even more preferably in the range from 18 to 20 bar.

To extract the ammonium carbamate and ammonia in an aqueous solution containing urea, ammonium carbamate and ammonia, the corresponding decompression, is sent to the device 17 dissociation operating at medium pressure and can be found in section 16 of technological processing, where this part of the solution is subjected to dissociation of obtaining an aqueous solution of urea and a vapor phase containing ammonia, carbon dioxide and water. In particular, in dissociator 17 the above-mentioned aqueous solution containing urea, ammonium carbamate and ammonia, are subjected to thermal dissociation.

Thus obtained vapour phase containing ammonia, carbon dioxide and water, then sent for condensation in condenser 18, operating at medium pressure and can be found in section 16 of technological processing. In the condenser 18 will receive an aqueous solution of ammonium carbonate, which comes out of the condenser 18 and then sent to re-cycle in section 11 of the synthesis of urea (rector R).

In the example shown in figure 1, an aqueous solution of carbonate coming from the condenser 18, operating at medium pressure, is subjected to appropriate compression (compression), essentially a standard way, for example by means of a pump 19, p is after which sent for recycle to the reactor R section 11 of the synthesis of urea, working at high pressure, through the scrubber 14 and the capacitor 12 high pressure.

According to an alternative, not presented here, the example proposed in the present invention a method for at least part of the aqueous solution of carbamate coming from the condenser 18, operating at medium pressure, after appropriate compression, sent directly to the condenser 12 high pressure and then to the reactor R.

The remaining aqueous solution containing urea, ammonium carbamate and ammonia coming out of the reactor R and unpiloted to the Department of 16 processing at an average pressure, enters the stage of extraction of the ammonium carbamate and ammonia contained in such solution, in the synthesis loop at high pressure, the present invention method.

In particular, in accordance with the example of figure 1 the remaining part of the aqueous solution containing urea, ammonium carbamate and ammonia coming out of the reactor R section 11 of synthesis, refer to the Stripping tower 13 site Stripping, working at high pressure, in which this part of the aqueous solution is subjected to decomposition and Stripping in the presence of CO2and when heated. Such heating is provided by indirect heat exchange with steam flow S with the high temperature and pressure (n is an example, 211-223C and 20-25 bar). To ensure CO2served as odarivaemogo agent, use the original carbon dioxide C.

In accordance with the present invention a method of producing urea preferably provides that at least part of the condensed steam SC, leaving the Stripping column 13, were sent to the pipeline 32 in cracker 17. In dissociator 17 condensed SC pairs with relatively high temperature and pressure (high heat level, for example, 211-223C and 20-25 bar), preferably used to provide the heat required for dissociation of parts of an aqueous solution containing urea, ammonium carbamate and ammonia coming out of the reactor R and sent to the cracker 17.

Proposed in the present invention the method also includes the further step of feeding the aqueous urea solution obtained in step dissociation in the running average pressure dissociator 17, can be found in section 16 of technological processing, the apparatus 22 to decomposition, can be found in section 21 of the extraction of urea, operating at the prescribed low pressure, for example in the range from 1.5 to 9.5 bar, preferably in the range from 3 to 5 bar.

For this purpose aqueous urea solution leaving dissociator 17, is subjected to appropriate decompression (pressure drop), essentially in a standard way, for example by means of the valve 20.

In particular, as shown in the preferred example proposed in the present invention method, illustrated in figure 1, an aqueous urea solution leaving dissociator 17, can be found in section 16 of technological processing, are sent directly to the device 22 to decomposition, can be found in section 21 of the extraction of urea.

Moreover, again in accordance with the example illustrated in figure 1, the portion of the source carbon dioxide preferably is sent to the condenser 23, located in section 21 extraction of urea, working at low pressure.

For this purpose the said part of the original carbon dioxide sent into the condenser 23, is subjected to appropriate decompression, essentially, in a standard way, for example by means of the valve 30.

In the apparatus 22 to decomposition, can be found in section 21 of the extraction of urea, working at low pressure, aqueous urea solution coming from dissociator 17, located in section 16 process with an average pressure, is subjected to decomposition with the production of concentrated solution U of urea and second vapor phase comprising ammonia, carbon dioxide and water.

A concentrated solution U of urea, in which the concentration of urea is n the example, from 60 to 80 wt.%, preferably they exit from the apparatus 22 to decomposition, can be found in section 21 of the extraction of urea, for his direction on the final stages of technological processing of urea (essentially standard, therefore, not presented in this disclosure of the invention) according to the present method of producing urea, for example on stage vacuum decay and on stage granulating or pilirani obtained in the previous stages of urea.

On the other hand, the second steam phase containing ammonia, carbon dioxide and water received in the apparatus 22 to decomposition, can be found in section 21 of the extraction of urea, is sent to the condenser 23, which is in the same section 21, and, primarily, is subjected to condensation with the receipt of the circulating aqueous solution of carbamate.

As shown in the example illustrated in figure 1, the second steam phase containing ammonia, carbon dioxide and water, is preferably subjected to condensation with carbon source gas supplied in the above-mentioned capacitor 23.

In the condenser 23, located in section 21 extraction of urea, working at low pressure, direct also acceptable amount of an aqueous solution of carbamate (carbonate) with a concentration of condensation water in the range from 30 to 80 wt.%, to enable the con is Ansatie second vapor phase and accordingly, the source of carbon dioxide With formation of ammonium carbamate.

The aqueous solution W carbamate (carbonate), usually served from section processing process condensate and(or) from the tank with ammonia water, which, essentially, is the standard way and for this reason are not presented in this disclosure of the invention.

As shown in figure 1, in accordance with the proposed in the present invention a method of circulating an aqueous solution of carbamate obtained in the condenser 23, located in section 21 extraction of urea, working at low pressure, preferably direct to the condenser 18 medium pressure, can be found in section 16 of technological processing, for absorption (condensation) vapor phase containing ammonia, carbon dioxide and water, leaving operating at medium pressure dissociator 17.

In this case, the phase of compression of the circulating aqueous solution of carbamate coming from the condenser 23 to the operating pressure section 16 process also provides, essentially, a standard way, for example when using a pump 24.

According to a not represented here alternative example implementation proposed in this invention method, the stage of condensation in the condenser 18, located in section 16, the technology is tion processing at medium pressure, has two levels, which the heat of condensation, instead of transmitting a cooling fluid (typically, cooling water), mainly used to further increase the concentration of the concentrated solution U of urea coming from the device 22 to decomposition, can be found in section extraction of urea, working at low pressure.

In this case, the condensation heat released during condensation of the vapor phase, is transmitted through the auxiliary heat concentrated solution U of urea, promoting decomposition and, consequently, the separation of parts of ammonium carbamate, ammonia and water, which are still present in the above-mentioned solution, and further increasing the concentration of the contained urea.

Received on a repetitive cycle in the Stripping column 13 Stripping host high-pressure ammonia and carbon dioxide, obtained by Stripping the remaining part of the aqueous solution containing urea, ammonium carbamate and ammonia coming out of the reactor R, subjected to repeated condensation with the formation of ammonium carbamate in the condenser 12, located at the site of condensation at high pressure, and direction for a second cycle, in the form of ammonium carbamate in the reactor R, can be found in section 11 of the synthesis of urea.

The condensation of ammonia and carbon dioxide, leaving atpar the Oh column 13, in the condenser 12, operating at high pressure, is due to the absorption of the above-mentioned gases in the presence of a source of ammonia N (liquid) and an aqueous solution of carbamate coming after appropriate compression of the capacitor 18, located in section 16 process with an average pressure across the scrubber 14.

An aqueous solution containing urea, ammonium carbamate and ammonia obtained in the Stripping column 13, after passing through the above stages of decomposition and Stripping in the presence of CO2expose the corresponding decompression, essentially, in a standard way, such as by means of valve 25, to the working pressure section 21 extraction of urea and then sent to the device 22 for the decomposition of operating at low pressure, in the same section 21. Here, the above-mentioned solution is subjected to decomposition with the above-mentioned aqueous solution of urea coming from dissociator 17, located in section 16 process with an average pressure, to obtain a concentrated solution U of urea and second vapor phase comprising ammonia, carbon dioxide and water as described above.

Unreacted carbon dioxide, ammonia and water in the vapor phase present in section 11 of the synthesis of urea or, rather, in the reactor R, the output of the t of the latest and fed to the scrubber 14 high pressure. These pairs usually also contain inert gases (e.g. air)present in the original carbon dioxide C.

In the scrubber 14 mentioned above pairs is subjected to wet treatment (washing) with an aqueous solution of carbamate coming after appropriate compression of the capacitor 18, located in section 16 process with an average pressure, to extract present in the carbon dioxide and ammonia and separation of inert gases. Separated thus inert gases released into the atmosphere, essentially, in a standard way, additionally providing acceptable decompression of these gases, for example when using a valve 26. Alternatively, such inert gases may be directed to re-cycle for use in other sections (not shown). On the other hand, carbon dioxide and ammonia adsorbed in aqueous solution of carbamate coming from the condenser 18, is directed through the condenser 12 high pressure, to re-cycle in section 11 of the synthesis of urea or, rather, in the reactor R.

Figure 2 shows an installation for producing urea, generally designated by the number 10, which uses a method according to another exemplary embodiment of the present invention.

This method of producing urea is different from the method described to enter the, the fact that steam escaping from the condenser 12 of the condensation unit, operating at high pressure, is served by pipeline 33, in parallel with a part of the condensed steam SC departing from the Stripping node operating at high pressure (Stripping column 13), cracker 17, located in section 16 process under medium pressure.

In dissociator 17 condensed SC pairs and pairs extending from the condenser 12 to the high pressure, relatively high temperature and pressure (high heat level), mainly used to provide the heat required for dissociation of parts of an aqueous solution containing urea, ammonium carbamate and ammonia coming out of the reactor R and sent to the above-mentioned cracker 17.

For these purposes, the condensed steam is SC and steam exhaust from the condenser 12, the guide annulus, independently from each other, the corresponding camera dissociator 17, separated from each other essentially in the standard way, for example when using the corresponding tube 34.

In accordance with this example of the invention, the condenser 12, can be found in section 11 of the high pressure, preferably in the form of a capacitor submersible type heat exchanger having a tube bundle in which the cooling fluid L, as the rights of the lo, water flowing in the annular space of the specified heat exchanger is converted into steam by heat exchange with a solution obtained by mixing a solution of ammonium carbamate coming from the condenser 18 section 16 process at medium pressure (through the scrubber 14), the source of ammonia N and sent to the condensation of the vapor phase exiting the Stripping node of the high-pressure Stripping column 13).

In particular, using the proposed in the present invention method, good results were obtained by directing a pair of S with temperature ranging from 211 to 223C. and a pressure in the range of 20 to 25 bar, in the Stripping column 13, and the direction in cracker 17 100% condensed steam SC departing from the Stripping tower 13 and having essentially the same temperature and pressure as compared with the above-mentioned high heat level. Good results were also obtained due to the direction in cracker 17 in condensed steam SC and in parallel with the latter, and also part of the pair extending from the condenser 12 of the condensation unit, operating at high pressure and / or by directing a certain amount of initial carbon dioxide, in the range from 1 to 5 wt.%, more preferably in the range of 2 to 3 wt.% of the total number of source dioxide angle of the ode, supplied to the plant 10, the capacitor 23, located in section 21 extraction of urea, working at low pressure.

Moreover, an aqueous solution containing urea, ammonium carbamate and ammonia is directed to section 16 process when the average pressure is preferably from 10 to 50 wt.%, even more preferably from 10 to 25 wt.% from the aqueous solution, leaving section 11 of the synthesis of urea.

The above-described structural features of the system 10 to obtain a urea synthesis technology from ammonia and carbon dioxide in accordance with the present disclosure of the invention will become better understood with reference to the accompanying drawings.

In accordance with the present invention, the system 10 consists of section 11 of the synthesis of urea at high pressure, the Stripping node of the high-pressure Stripping column 13), section 16 process at the average pressure and sections 21 extraction of urea, working at low pressure, between which there is a message.

Section 16 process mainly includes cracker 17 operating at medium pressure, and the condenser 18, operating at medium pressure, between which there is a message. In turn, section 21 extraction of urea includes apparatus 22 for the decomposition of operating at low the t and the capacitor 23, working at low pressure, between which also has a message.

The installation 10 includes the appropriate pipelines to supply reagents, carbon dioxide, ammonia N, and also for feeding the aqueous solution W carbamate (carbonate)containing condensation water, as well as connecting lines between the different sections and corresponding apparatus, schematically represented in the form of various flow lines in figure 1 and 2.

In particular, the system 10 connecting lines 28 and 29 primarily designed to provide a direct connection between the section 11 of the synthesis of urea and dissociation 17, located in section 16 process at medium pressure, and, respectively, between this apparatus and the apparatus 22 to decomposition, can be found in section 21 of the extraction of urea, working at low pressure.

In accordance with the present invention the system 10 also includes a connecting pipe 32 for supplying condensed steam SC departing from the Stripping tower 13 Stripping node, cracker 17.

In addition, according to a preferred variant of the present invention also provides a pipe 27 for supplying a source of carbon dioxide in the condenser 23, located in section 21 extraction of urea, operating at low pressure, the NII.

According to a not represented here alternative example installation 10 according to the present invention, the capacitor 18 medium pressure includes a standard tube bundle, providing links from the inside, i.e. on the pipe space, with a strong solution U of urea coming from the apparatus 22 for decomposition, and providing the message from the outside, i.e. in the annular space with a vapor phase containing ammonia, carbon dioxide and water, leaving dissociator 17 operating at medium pressure, as well as with circulating aqueous solution of carbamate coming from the condenser 23, working at low pressure, to obtain the above-described double effect.

In accordance with a variant of the present invention, is illustrated in figure 2, the system 10 further includes a connecting pipe 33 between the condenser 12 of the condensation unit, operating at high pressure, and dissociation 17, located in section 16, operating at medium pressure.

In this regard, the capacitor 12 Stripping node high pressure is a capacitor submersible type, comprising a tube bundle, and a connecting pipe 33 serves to provide fluid communication with the annular space above the heat exchanger.

From the preceding description it is clear that the method of producing urea in the present is the invention solves the above technical problem and has numerous advantages, the first of which is due to the fact that this method can significantly reduce the energy consumption due to the recovery of at least part of the heat of the condensed steam, the exhaust from the Stripping node high pressure to heat parts of a solution containing urea, ammonium carbamate and ammonia, leaving sections of the synthesis at high pressure and subjected to dissociation in the partition process under medium pressure.

Moreover, in the application proposed in this invention method, it is possible to achieve a higher degree of conversion in the high pressure circuit in comparison with the degree of conversion offered in the previous prior art, in particular in the section of the synthesis of urea, for example, from 58 to 62 wt.%, what is relevant also for cases of reconstruction of existing large power plants, such as plants that produce from 3000 to 4500 metric tons of urea per day.

Another advantage is that thanks to the present invention and, in particular, the high degree of conversion, it becomes possible to reduce energopotreblenie circuit synthesis, working at high pressure, as well as sections of the extraction of urea, working at low pressure, as compared with the methods proposed prior art. From this the following is the duty to regulate, that same power and same size of the apparatus, which is installed to obtain urea proposed in the present invention method allows to operate such plants with higher productivity compared with other methods of the prior art. In other words, with the same production capacity of the installation, which uses proposed in the present invention method can be smaller in size and therefore be more cost-efficient and have lower operating costs compared with plants of similar capacity, which methods are applied, the proposed prior art.

In addition, the practical implementation of the above method is rather simple, reliable and requires significant investment.

The above-mentioned advantages, mainly related to the fact that, due to the studies, it was found that the exposure of an aqueous solution of urea, obtained at the stage of dissociation in the processing section average pressure, decomposition at low pressure, the number (in absolute value) of the condensation water contained in the aqueous solution W carbamate (carbonate)required for such condensation is the formation of ammonium carbonate, significantly less compared to the amount of condensation water, which is necessary according to other methods of technology.

Considering the fact that the above-mentioned condensation water is reused in the section of the synthesis of urea with ammonium carbamate and taking into account the fact that water is a reaction product during the synthesis of urea and, consequently, has a negative effect on the degree of conversion of the reactants, the fact that the possible reduction of the above-mentioned amount of condensation water leads to a corresponding increase in the degree of conversion compared to other processes known from the prior art.

In particular, unlike the present invention methods, the proposed prior art that is necessarily included in the partition process at medium pressure stage of Stripping in the presence of carbon dioxide, an aqueous solution of urea, prior to the step of thermal dissociation in the aforesaid section, and the stage of condensation by adding a source of ammonia. In order to achieve efficient and complete condensation of such quantities of source carbon dioxide and ammonia, received in the partition process with an average pressure of obtaining ammonium carbamate, there is a need to supply significantly Bo is further amount (in absolute value) the condensation of water in the extraction section of urea, working at low pressure, as compared with the method proposed in the present invention.

As an example, it was noted that under the same operating conditions specified above, the amount of the condensation water contained in the aqueous solution W carbamate (carbonate), by the method proposed in the present invention, was 10-25 wt.% compared with the methods of the prior art, with a corresponding increase in the conversion rate of 2-3% in the section of the synthesis of urea, operating at high pressure.

Among the numerous advantages offered by the present invention, it is important to note the possibility of increasing the production capacity of the existing plant production of urea from ammonia and carbon dioxide as compared to the design capacity for which such facilities were designed to be simple, efficient and reliable way, while reducing operating costs and energy consumption of the existing installation. Preferably, it is also possible that a significant increase in the production capacity of the existing installation, for example by 30-50%compared to its design capacity.

In accordance with a preferred example of the invention illustrated in figure 1, a system 10 for obtaining urea is an installation, polucen the Yu proposed by the present invention a method of reconstruction of the existing plant for producing urea from ammonia and carbon dioxide, contains: section 11 synthesis of urea at high pressure, the node 13 bog at high pressure of the urea solution obtained in section 11, and section 21 extraction of urea, working at low pressure, comprising the apparatus 22 for decomposition and the capacitor 23; however, these sections 11, 13 and 21 are communicated with each other, and this method differs in that it provides (set):

section 16 for processing at medium pressure part of the urea solution obtained in section 11 of the synthesis of urea, including cracker 17 and capacitor 18, while section 16, operating at medium pressure, has a message section of the synthesis of urea, working at high pressure, and, accordingly, section 11, 21 extraction of urea, working at low pressure;

a connecting pipe 29 between dissociation 17, located in section 16 process at medium pressure, and a device 22 for decomposition, can be found in section 21 of the extraction of urea, working at low pressure;

the connecting pipe 32 between the Stripping node 13 high pressure and dissociation 17, located in section 16 process with an average pressure for feeding the condensed steam from the Stripping node 13 in cracker 17.

In preferred embodiments, the implementation in the way mo is ernestii the present invention also provides a connecting pipe 33 between the section 12 of the condensation at high pressure existing installation to obtain urea and dissociation 17, under section 16 of technological processing, with an average pressure for steam extending from the node 12 condensation in cracker 17.

It is also preferable that proposed in the present invention the method comprises the further step of providing pipe 27 for supplying a source of carbon dioxide in the condenser 23, located in section 21 extraction of urea, working at low pressure.

Naturally, the experts in the art may devise numerous modifications and variations of the above-described method of producing urea to meet their specific conditions and requirements, within the scope of the present invention, in accordance with the following claims.

1. A method of producing urea from ammonia and carbon dioxide, comprising the following steps:
the supply of ammonia and carbon dioxide in the section of the synthesis of urea, operating at a predetermined high pressure,
the introduction of ammonia and carbon dioxide in the reaction section synthesis of obtaining an aqueous solution containing urea, ammonium carbamate and ammonia,
submission of the first part of the aqueous solution containing urea, ammonium carbamate and ammonia, in the section process running at a given mean pressure for the extraction of ammonium carbamate and ammonia, containing the s in this solution,
exposure to the first part of the aqueous solution containing urea, ammonium carbamate and ammonia dissociation in the partition process of obtaining an aqueous solution of urea and a vapor phase containing ammonia, carbon dioxide and water,
exposure specified vapor phase containing ammonia, carbon dioxide and water condensation in the partition process of obtaining an aqueous solution of ammonium carbamate,
the direction of an aqueous solution of ammonium carbamate to repeat the cycle section of the synthesis of urea,
characterized in that it also comprises the following steps:
submission of an aqueous solution of urea, obtained at the stage of dissociation in the processing section in the apparatus for decomposition, can be found in section extraction of urea and operating at a predetermined low pressure,
exposure of an aqueous solution of urea decomposition apparatus for decomposing section extraction of urea to obtain a concentrated solution of urea and a second vapor phase containing ammonia, carbon dioxide and water,
exposure to second vapor phase condensation in the condenser section of the extraction of urea and soobshayem with the aforementioned apparatus for decomposition, with receipt of the first circulating an aqueous solution of ammonium carbamate,
the exposure of the second part of an aqueous solution containing urea, the ammonium carbamate and ammonia Stripping with heat in the Stripping node in the primary at a given high pressure to obtain a second aqueous solution of urea and a third vapor phase containing ammonia, carbon dioxide and water, these heating is provided by indirect heat exchange with a stream of steam, condenses, forms a condensed steam,
using at least part of the condensed steam as a coolant for the implementation of the dissociation of the first part of an aqueous solution containing urea, ammonium carbonate and ammonia, in the node for dissociation under section processing under medium pressure.

2. The method according to claim 1, characterized in that the said steam used for heating, and the condensed steam, have a temperature of from 200 to 235C and a pressure of from 15 to 30 bar.

3. The method according to any of the preceding paragraphs, characterized in that the said at least part of the condensed steam used for dissociation at an average pressure is from 80 to 100% of the total number of condensed steam, obtained by indirect heat exchange in said Stripping node high pressure.

4. The method according to claim 1, characterized in that it further includes the following steps:
the exposure of the third vapor phase containing ammonia, carbon dioxide coal is ode and water, obtained in the Stripping node, condensation in the condensation unit mainly with said predetermined high pressure to obtain a second circulating an aqueous solution of ammonium carbamate,
submission of the second aqueous urea solution obtained in the Stripping unit in the apparatus for the decomposition in section extraction of urea at low pressure.

5. The method according to claim 4, characterized in that the condensation unit at high pressure includes a capacitor submersible type and the above-mentioned condensation occurs in the condenser due to the contact of the third vapor phase with a circulating aqueous solution of ammonium carbamate and, optionally, with liquid ammonia with recovery of the heat of condensation by indirect heat exchange to form a pair.

6. The method according to claim 5, characterized in that it also includes the stage of use of the steam formed in the capacitor node condensation at high pressure, in parallel with at least part of the condensed steam as a coolant for the dissociation mentioned the first part of an aqueous solution containing urea, ammonium carbamate and ammonia, in the node dissociation section of the process under medium pressure.

7. The method according to claim 5, characterized in that the said circulating solution of ammonium carbamate is at least part of the solution, obtained by condensa the AI in the partition process under medium pressure.

8. The method according to claim 7, characterized in that the said at least part of the solution, obtained by the condensation section processing with an average pressure, return through the scrubber in the above-mentioned capacitor node condensation at high pressure.

9. The method according to claim 1, characterized in that it also comprises the following steps:
supply of carbon dioxide in the condenser section of the extraction of urea, the exposure of the carbon dioxide from the second vapor phase condensation in the condenser section of the extraction of urea with the receipt of the circulating aqueous solution of ammonium carbamate.

10. The method according to claim 9, characterized in that the amount of carbon dioxide supplied to the condenser section of the extraction of urea is from 1 to 10 wt.% of the total number of source carbon dioxide.

11. The method according to claim 1, characterized in that the said aqueous solution containing urea, ammonium carbamate and ammonia is supplied to the processing section operating at medium pressure ranges from 10 to 50 wt.% from the aqueous solution obtained in section synthesis and containing urea, ammonium carbamate and ammonia.

12. The method according to claim 1, characterized in that the said average pressure at which the working section processing, is from 10 to 70 bar.

13. The method according to claim 1, characterized in that the said circulating aqueous solution of ammonium carbamate, obtained in the condenser section of the extraction of urea at low pressure, refer to the section of the processing at the above-mentioned step of condensation of the vapor phase containing ammonia, carbon dioxide and water.

14. The method according to claim 1, characterized in that the said stage of condensation of the vapor phase containing ammonia, carbon dioxide and water, in the partition process is two-stage.

15. Installation (10) for obtaining urea from ammonia and carbon dioxide by the method according to claim 1 that contains the partition (11) synthesis of urea at high pressure section (16) process with an average pressure of the first part of the urea solution obtained in section (11) synthesis with dissociation (17) and the condenser (18), a Stripping unit (13) high-pressure Stripping unit at a high pressure second part of the urea solution obtained in section (11) synthesis, and section (21) extraction of urea at low pressure, comprising the apparatus (22 for decomposition and the condenser (23), and these sections (11, 13, 16, 21) communicate with each other, characterized in that it also includes a connecting pipe (29) between dissociation (17) of section (16) processing at the average pressure and the apparatus (22)intended for decomposition in section (21) extraction of urea at low pressure, and a connecting pipe (2) between the Stripping node (13) high pressure and dissociation (17) of section (16) process with an average pressure, intended for the supply of condensed steam (SC), departing from the Stripping node (13), cracker (17).

16. Installation (10) according to 15, characterized in that it also includes the pipeline (27) for supplying a source of carbon dioxide (C) in the condenser (23) section (21) extraction of urea at low pressure.

17. Installation (10) according to item 15 or 16, characterized in that it also includes a connecting pipe (33)disposed between the node (12) condensation at high pressure and the said dissociation (17) of section (16) process with an average pressure, designed for steam extending from the node (12) condensation, cracker (17).

18. Installation (10) according to 15, characterized in that the capacitor (18) of section (16) process with an average pressure includes a tube bundle, providing links on-line space with a strong solution (U) of urea leaving the apparatus (22) for the decomposition in section (21) extraction of urea at low pressure, and the annular space with a vapor phase containing ammonia, carbon dioxide and water in and out of dissociator (17) of section (16) process with an average pressure, as well as with circulating aqueous solution carbamate leaving the condenser (23) section (21) extraction of urea at low pressure is I.

19. The method of reconstruction of the existing plant for producing urea from ammonia and carbon dioxide, contains the partition (11) synthesis of urea at high pressure, a Stripping unit (13) high-pressure Stripping unit at a high pressure of the urea solution obtained in section (11), and section (21) extraction of urea at low pressure, comprising the apparatus (22) for the decomposition and the condenser (23), and these sections (11, 13, and 21) communicate with each other, characterized in that it comprises the following steps:
the provision of section (16) for processing under medium pressure part of the urea solution obtained in section (11) of the synthesis of urea, and this section (16), operating at medium pressure, includes cracker (17) and the condenser (18) and is connected with the section of the synthesis of urea at high pressure and, respectively, with section (11, 21) extraction of urea at low pressure,
the provision of the connecting pipe (29) between dissociation (17) of section (16) processing at the average pressure and the apparatus (22), intended for the decomposition in section (21) extraction of urea at low pressure,
the provision of the connecting pipe (32) between the Stripping node (13) high pressure and dissociation (17) of section (16) process with an average pressure, intended to supply the outdoor is consistent pair (SC) of the Stripping node (13) cracker (17).

20. The method according to claim 19, characterized in that it further provides a pipe (27) for supplying a source of carbon dioxide (C) in the condenser (23) section (21) extraction of urea at low pressure.

21. The method according to claim 19 or 20, characterized in that it further provides a connecting pipe (33) between node (12) condensation at high pressure existing installation to obtain urea and dissociation (17) of section (16) process with an average pressure, designed for steam extending from the node (12) condensation, cracker (17).



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention refers to the way of carbamide production at higher temperatures and under the pressure in the installation that contains a high pressure section including a reactor, stripper, condenser and gas washer. The method includes interaction between ammonia and carbon dioxide in the reactor with formation of the reactor feed and separate withdrawal of the liquid flow containing carbamide, ammonium carbamate and free ammonia in water solution from the reactor, and the gas flow containing predominantly inert gases. The flows of liquid and gas carbon dioxide are fed to the high pressure section. The liquid flow from the reactor is for to the stripper for partial decompounding of the ammonium cabamade and partial release of the free ammonia in the current of the gas carbon dioxide that is introduced into the stripper and includes ammonia and carbon dioxide admixed with water vapour, and of the liquid flow including carbamide and residual ammonium carbamade in the water and ammonia solution. The liquid flow from the stripper is fed at the stage of subsequent decompounding of the ammonium carbamade and separation of ammonia and carbon dioxide thus obtaining carbamide and recirculating liquid flow containing ammonium carbamade in the water and ammonia solution. The gas flow from the stripper is fed to the condenser for partial absorption and condensation in the course of mixing with ammonia and the liquid flow from the gas washer. The liquid flow from the condenser is fed to the reactor. The gas flow from the reactor is cleaned from ammonia and carbon dioxide while contacting with the recirculating liquid flow in the gas washer. The flow of liquid carbon dioxide is introduced into the reactor or condenser after it has been mixed with another process flow; the flow of liquid carbon dioxide is mixed with the liquid flow coming out from the gas washer or the condenser.

EFFECT: improvement of reliability of the applied equipment.

4 cl, 3 dwg, 3 ex

FIELD: chemistry.

SUBSTANCE: carbamide is obtained at high temperature and pressure in an apparatus having a high-pressure section, including a reactor, a stripper, a condenser and a scrubber, using a method which involves reaction of ammonia and carbon dioxide in the reactor to form a reaction mixture and separate outlet from the reactor of a liquid stream containing carbamide, ammonium carbamate and free ammonia in aqueous solution, and a gas stream mainly containing inert gases, feeding into the high-pressure section streams of liquid and gaseous carbon dioxide, feeding the liquid stream from the reactor into the stripper for partial decomposition of ammonium carbamate and partial extraction of free ammonia in the current of gaseous carbon dioxide fed into the stripper to obtain a gas stream containing ammonia and carbon dioxide with a water vapour impurity, and a liquid stream, feeding the liquid stream from the stripper to the next ammonium carbamate decomposition step and separating ammonia and carbon dioxide to obtain carbamide and a recycled liquid stream containing ammonium carbamate in an aqueous ammonium solution, feeding the gas stream from the stripper into the condenser for partial absorption-condensation thereof while mixing with ammonia and the liquid stream from the scrubber, feeding the liquid stream from the condenser into the reactor, removing ammonia and carbon dioxide from the gas stream from the reactor upon contact with the recycled liquid stream in the scrubber, where the stream of liquid carbon dioxide is fed into the high-pressure section after mixing with another process stream, where the stream of liquid carbon dioxide is mixed with a gas stream coming from the stripper or condenser, in the apparatus for mixing said streams, where when feeding the liquid stream into an insert with a variable cross-section through a convergent nozzle and the gas stream into the housing, liquid carbon dioxide evaporates through contact in the insert with part of said gas stream entering the insert, followed by contact of the mixed stream at the outlet of the insert with the remaining part of the gas stream passing through a slit between the insert and the housing.

EFFECT: high reliability of the used equipment.

4 cl, 3 ex, 4 dwg

FIELD: medicine, pharmaceutics.

SUBSTANCE: invention relates to method of obtaining carbamide with stable carbon isotope 13C for application in medical diagnostics of gastrointestinal tract diseases. Claimed method has two stages, the first stage includes interaction of labeled carbon dioxide and propylene oxide at temperature 120-130C and pressure 1.3-1.5 MPa in presence of catalyst with further isolation of labeled propylene carbonate. Catalyst of the first stage is complex of zinc bromide with tertiary organophosphine or 1-butyl-3-methylimidasolium chloride, and mole ratio of propylene oxide to catalyst constitutes 500-2000:1. At the second stage carried out is ammonolysis of isolated liquid propylene carbonate at temperature 130-150C and pressure 5.0-7.0 MPa with further isolation of target product.

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: chemistry.

SUBSTANCE: invention relates to a novel method of producing carbamide with a stable 13C isotope used in medical diagnostics, involving reaction of labelled carbon dioxide and ethylene oxide at temperature 80-150C, pressure 2.1-6 MPa in the presence of a catalyst - complex of zinc bromide and tertiary organophosphines in molar ratio of ethylene oxide to the catalyst equal to 500-5000:1, followed by extraction of the labelled ethylene carbonate and ammonolysis of the extracted ethylene carbonate at temperature 120-170C and pressure 2.8-4.7 MPa.

EFFECT: possibility of obtaining an end product with good output using a fairly simple and technologically effective method.

4 cl, 14 ex, 2 tbl

FIELD: chemistry.

SUBSTANCE: method of producing urea from ammonia and carbon dioxide involves the following steps: feeding ammonia and carbon dioxide into a urea synthesis section working at given high pressure, reaction of ammonia and carbon dioxide in the synthesis section to obtain aqueous solution containing urea, ammonium carbamate and ammonia, feeding a portion of the said aqueous solution containing urea, ammonium carbamate and ammonia into a processing section working at given average pressure for extraction of ammonium carbamate and ammonia contained therein, dissociation of the said portion of the aqueous solution containing urea, ammonium carbamate and ammonia in the processing section to obtain 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 solution of ammonium carbamate, recirculation of said aqueous solution of ammonium carbamate into the urea synthesis section, feeding the remaining portion of the said aqueous solution containing urea, ammonium carbamate and ammonia into a decomposition apparatus in the urea extraction section through an evaporation zone, essentially working at said given high pressure, and characterised by that it also involves the following steps: feeding aqueous solution of urea obtained after dissociation in the processing section into the decomposition apparatus in the urea extraction section working at given low pressure, decomposition of the aqueous solution of urea in the decomposition apparatus of 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 the condenser of the urea extraction section linked with said decomposition apparatus to obtain recycled aqueous solution of ammonium carbamate. The invention also relates to apparatus for realising said method and a method of renovating an already mounted installation.

EFFECT: high conversion of carbon dioxide to obtain urea with low power consumption.

12 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to basic organic synthesis and a method of producing ethylene glycol together with carbamide from carbon dioxide, ethylene oxide and ammonia. The method involves carrying out the process in two steps: first, reaction of carbon dioxide and ethylene oxide at temperature 80-150C, pressure 2.1-6 MPa in the presence of a homogeneous catalyst - complex of zinc bromide with tertiary organophosphines with subsequent extraction of ethylene carbonate, followed by ammonolysis of ethylene carbonate in a single process step in ether-type solvents which partially dissolve carbamide, at temperature 120-170C and pressure 2.8-6 MPa to obtain ethylene glycol and carbamide.

EFFECT: method enables virtually complete conversion of starting material to the end products, and also considerably lowers power consumption due to improvement of the process of separating ethylene glycol and carbamide.

3 cl, 2 tbl, 14 ex

FIELD: chemistry.

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

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

13 cl, 2 dwg

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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