The way co-production of ammonia and urea, the installation for implementing the method, the way of modernization of the facilities of the synthesis of ammonia and urea

 

(57) Abstract:

The way co-production of ammonia and urea are carried out by the technological scheme includes a reactor for the synthesis of ammonia, the section of the synthesis of the carbamate, the reactor for the synthesis of urea, but also the regeneration section of the urea. Part of the stream containing carbamate in aqueous solution coming from the regeneration section of the urea treated with partial decomposition of the carbamate to obtain a flow comprising ammonia and carbon dioxide in vapour phase and a flow comprising diluted carbamate in aqueous solution. The obtained diluted carbamate together with a gas flow comprising hydrogen, nitrogen and carbon dioxide, preferably obtained at the stage of reforming of hydrocarbons, join c by a stream of ammonia coming from the synthesis reactor ammonia. The mixture is sent to a section of the synthesis of carbamate, where ammonia and carbon dioxide receive a flow comprising carbamate in aqueous solution, and a gas flow comprising hydrogen and nitrogen. The flow comprising carbamate in aqueous solution, and then sent to the reactor for the synthesis of urea, while the gas flow comprising hydrogen and nitrogen, is directed to a reactor for the synthesis of ammonia. Installation for assetbased with the reforming section, reactor for the synthesis of carbamate and urea, as well as sections of regeneration and concentration of urea. Modernization of individual plants for the synthesis of ammonia and urea involves the creation of the technological cycle specified above. The technical result - the reduction of capital, energy and material costs. 3 C. and 20 C.p. f-crystals, 1 Il.

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

In the following description and in the following claims the term: "method for simultaneous production of ammonia and urea is expected to identify a single method that combines the method of production of ammonia to the method of manufacture of urea.

In other words, according to this technology, urea is produced, at least partially, by carrying out the synthesis of synthetic ammonia in the reactor to interact with carbon dioxide contained in the synthetic crude gas stream, including among other products hydrogen and nitrogen included, for example, from a section of the reformer. Synthetic crude haseotes of this type allow you to exclude or in any case reduce to a noticeable extent section decarbonization synthetic crude gas stream, partition separating the ammonia obtained in the corresponding synthetic reactor, and the section of the compression of carbon dioxide. In addition, the consumption and investment resulting from a single integrated system, can be essentially lower than these parameters, which is the result of two separate methods for ammonia and urea.

The need to provide United way is especially noticeable in all cases where the whole, or, in some cases, where most of the ammonia is converted into urea due to its interaction with the carbon dioxide obtained as a side product in the preparation of synthetic gas.

In the following description and in the subsequent claims, the term: "the regeneration section of the urea is expected to designate part of the installation of the lower flow reactor for the synthesis of urea, including one or two reactor for the decomposition of the carbamate with an average pressure (18 bar), respectively, at average and low pressure (4 bar) and adjacent urethane capacitors, whose function is to separate the obtained urea from the reaction mixture leaving the corresponding synthesis reactor, allowing in this way recip is estline the above method, and also to the method of simultaneous upgrade of ammonia production and installation of production of urea.

In the following description and in the subsequent claims, the term: "simultaneous modernization" is supposed to denote the upgrade, which comes at the same time and an existing installation of ammonia synthesis, and an existing installation of the synthesis of urea with the aim of combining them.

The Association between methods of production of ammonia and urea, where the carbon dioxide contained in the synthetic crude gas, and synthetic ammonia is forced to interact with the formation of an aqueous solution of carbamate, which is sent to the synthesis reactor urea, includes, on the one hand, simplifying installation with particular reference to section decarbonization and separation of ammonia with section compression CO2but on the other hand, a noticeable corporacracy sections associated with the production of urea, mainly due to the lack of heat and excess molar relation of H2O/CO2in the reactor for the synthesis of urea, with a low degree of conversion and high power consumption.

As a consequence, in the field of joint proizvodsto transformation of urea in a simple way with low current consumption and investment.

The level of technology.

In order to satisfy the above requirements, it was suggested that in some ways co-production of ammonia and urea.

For example, in U.S. Patent US-A3303215 and US-A-3310376 reveals the way co-production according to the previously known prior art, where respectively purified liquid ammonia is loaded into the reactor for the synthesis of urea, where the ammonia is subjected to interaction with carbon dioxide contained in the synthetic crude gas comprising hydrogen and nitrogen.

In the reactor for the synthesis of urea from ammonia and carbon dioxide interact and form ammonium carbamate, which, in turn, is converted into urea by dehydration.

The first disadvantage of this process lies in the fact that the achievement of high values of heat produced in the production of carbamate, and the presence of inert gases (hydrogen and nitrogen), which partially reduces the pressure of the ammonia and carbon dioxide, makes it necessary operation in the reactor for the synthesis of urea at high pressures to maintain the reacting substances in the liquid phase, with a consequent high consumption and investment is of carbamate in aqueous solution to facilitate the absorption of carbon dioxide in aqueous ammonia and subsequent conversion to carbamate the molar ratio of N2O/CO2in a mixed reactor is relatively high, and the degree of conversion is poor.

Another disadvantage lies in the structural and operational complexity of the reactor for the synthesis of urea required for the implementation of the method described above, which must include a special device for separating inert gases (hydrogen and nitrogen) from carbon dioxide and ammonia in the vapor phase.

According to the method of the previous prior art is also provided by the stage of condensation and separation of ammonia, derived from unreacted gases, typical methods of producing ammonia, which is likely required from an economic point of view and from the point of view of energy consumption.

In U.S. patent US-A-3349126, US-A-4012443, US-A-4013718 and USA-4320103 reveals another way in which carry out phase separation to absorb carbon dioxide and synthesis of carbamate.

As the closest analogue may be taken patent US 4012443 And describing how co-production of ammonia and urea on the installation comprising a reactor for the synthesis of ammonia synthesis reactor urea and the regeneration section of the urea.

In this case, the absorption of carbon dioxide and the subsequent conversion to the carbamate takes place in an environment enriched water, which is then sent together with the carbamate synthesis reactor urea.

In addition, the heat of formation of carbamate, which is released in the process of absorption of carbon dioxide by aqueous ammonia, causes severe evaporation of the latter, which includes the need for additional regeneration of ammonia at the outlet section of the synthesis of the carbamate with addressing the problems of excessive dilution of the carbamate. At the same time, as in the reactor conversion of urea is not enough heat for the formation of carbamate, the conditions specified in the reactor become more difficult.

In other words, according to the method previously known prior art, the production of carbamate outside of the reactor for the synthesis of urea involves not only the loss, ecii with subsequent dehydration of urea and thus it is not possible to obtain a satisfactory degree of conversion.

As the closest analogue can also be availed plant for combined production of ammonia and urea in patent US 4320103 And includes a reactor for the synthesis of ammonia, the section of the synthesis of the carbamate, the reactor for the synthesis of urea and the regeneration section of the urea.

In conclusion, the methods for co-production of ammonia and urea according to the prior art, in addition to the required very complex installations for their implementation and including high investment costs and high energy consumption, do not allow in any case to obtain a high degree of conversion of urea due to excess molar relation of H2O/CO2present in the corresponding synthetic reactor.

Because of these disadvantages of the above methods is not found up to the present time the particular application, despite the growing need in this area.

Summary of the invention.

The problem underlying the present invention is that provides a method for simultaneous production of ammonia and urea, which allows, on the one hand, to achieve a high degree of conversion, and which, on the other M energy.

The above problem is solved according to the invention using the method of the above type, which includes stages:

treatment with partial decomposition of at least part of the flow comprising carbamate in aqueous solution coming from the specified partition regeneration of urea, for obtaining a flow comprising ammonia and carbon dioxide in vapour phase and a flow comprising diluted carbamate in aqueous solution;

supply the specified stream comprising ammonia and carbon dioxide in vapor phase in the reactor for the synthesis of urea;

supply the specified flow comprising diluted carbamate in aqueous solution arising from this stage of processing, a gas flow comprising hydrogen, nitrogen and carbon dioxide, preferably obtained by reforming hydrocarbon vapor and a flow comprising ammonia coming out of the reactor for the synthesis of ammonia in section synthesis of carbamate,

interaction specified ammonia with the specified carbon dioxide in the specified section of the synthesis of carbamate, receiving a flow comprising carbamate in aqueous solution and the gas flow comprising hydrogen and nitrogen;

supply the specified flow comprising carbamate in aqueous solution in the specified rear synthesis of ammonia.

Mainly thanks to the method according to the present invention and, in particular, the stage of partial decomposition of carbamate coming from the regeneration section of the urea, it is possible to send in the section synthesis of carbamate vodoobortnyh solution and send at the same time in the reactor for the synthesis of urea flow comprising ammonia and essentially anhydrous carbon dioxide, which reduces the molar ratio of N2O/CO2in this reactor, thereby increasing the degree of conversion of urea.

Thus, in addition to saving molar ratio of N2O/CO2in the reactor for the synthesis of urea becomes possible mainly operate at least part of the water included in the carbamate in aqueous solution coming from the regeneration section of urea, recyclist its simple and effective method in section synthesis of carbamate, in order to facilitate the absorption of carbon dioxide and save carbamate obtained in aqueous solution, preventing, thus, undesired crystallization.

Another advantage, which is manifested from this method is actually that, sending in the reactor for the synthesis of urea gas the reactions required for the synthesis of urea directly from the heat, generated by the reaction between ammonia and carbon dioxide in the reactor for the synthesis of urea (the heat of formation of carbamate). In doing so, it becomes possible to eliminate the problem of heat balance in the reactor for the synthesis of urea, even in those cases, when essentially all of the carbon dioxide included in the synthetic crude gas, is converted into the carbamate in a particular section of the synthesis.

Therefore, the method according to the present invention allows an extremely simple and efficient method for simultaneous production of ammonia and urea at low investment and low cost, and low power consumption and high degree of conversion of urea.

In contrast to the methods according to the previously known prior art, the present method mainly eliminates burdensome the extraction of ammonia by condensation or absorption of the unreacted gases.

Indeed, according to the present invention, the ammonia and carbon dioxide are allocated at the same time from the respective streams and sent directly to the interaction in a single section of the synthesis of carbamate due to the exploitation of their S="ptx2">

Preferably the stream exiting the reactor for the synthesis of ammonia, includes ammonia in the vapor phase, so that the synthesis of ammonium carbamate may be at least partially in the gas phase, with extremely fast reaction between ammonia and carbon dioxide, which does not require pre-absorption of carbon dioxide in the stream, including ammonia.

If in section synthesis of carbamate will require a higher amount of water than the number included in the diluted flow comprising carbamate in aqueous solution formed at the stage of processing, the method according to the present invention mainly includes a further stage feed stream comprising water coming from the section of the concentration of urea in the specified section of the synthesis of the carbamate.

Thus, by recycling water from one of the sections of the lower flow reactor for the synthesis of urea, then there is no need to send in the section synthesis of carbamate stream comprising water coming from outside the process, thus generating savings in production costs.

In order mainly to increase the degree of conversion of urea, the method according to the present sabreen in aqueous solution, received in the specified section of the synthesis of carbamate, with partial decomposition to obtain a flow comprising ammonia and carbon dioxide in vapour phase and a flow comprising diluted carbamate in aqueous solution;

supply the specified stream comprising ammonia and carbon dioxide in vapor phase in the specified reactor for the synthesis of urea;

supply the specified flow comprising diluted carbamate in aqueous solution, appearing at this stage of processing, the gas stream into the specified section of the synthesis of the carbamate.

In fact, by doing so, it becomes possible to refer to the section synthesis of carbamate anhydrous stream comprising ammonia and carbon dioxide, which allows to further reduce the molar ratio of N2O/CO2with a guaranteed increase the degree of conversion, mainly recyclist in section synthesis of carbamate water present in the flow of carbamate coming out this section.

In order to control the temperature inside the reactor for the synthesis of urea and to ensure optimum production conditions for the conversion of the urea, the method according to the present invention further involves the following stages:

- pre-heat flow, varicella heated stream, including ammonia, in the specified reactor for the synthesis of urea.

In accordance with an alternative method according to the present invention, the temperature inside the reactor for the synthesis of urea is controlled due to the fact further stages include:

- cooling flow comprising ammonia and carbon dioxide in vapour phase coming from the stage partial decomposition of the specified carbamate;

- feeding the cooled stream into the specified reactor for the synthesis of urea.

The above two alternatives allow for direct and effective control of the temperature in the reactor for the synthesis of urea, allowing you to apply the exact amount of heat necessary for a high degree of conversion.

In the first case, the reactor for the synthesis of urea is loaded, respectively, the pre-heated stream comprising retalitory ammonia, while in the second case, the flow comprising ammonia and carbon dioxide in vapour phase, respectively, is cooled before being filed in the reactor for the synthesis of urea.

To implement the above method, the invention provides a plant for combined production of ammonia and much the same:

means for feeding at least part of the flow comprising carbamate in aqueous solution coming from the specified partition regeneration of urea in the specified partition decomposition;

means for feeding the flow comprising ammonia and carbon dioxide in vapour phase obtained in the specified partition decomposition, in the specified reactor for the synthesis of urea;

the appropriate tool for flow comprising diluted carbamate in aqueous solution obtained in the specified partition decomposition, the gas flow comprising hydrogen, nitrogen and carbon dioxide, extending preferably from the hydrocarbon stream reforming section, and a flow comprising ammonia coming from the specified reactor for the synthesis of ammonia in the specified section of the synthesis of carbamate;

means for feeding the flow comprising carbamate in aqueous solution obtained in the specified section of the synthesis of the carbamate in the specified reactor for the synthesis of urea;

means for feeding a gaseous flow comprising hydrogen and nitrogen obtained in the specified section of the synthesis of the carbamate in the specified reactor for the synthesis of ammonia.

According to another aspect of the invention also provides a method for the simultaneous modernization osteoar synthesis of urea and the regeneration section of the urea, characterized in that it comprises the stage of:

the provision of section synthesis of carbamate and sections decomposition of carbamate;

providing means for feeding at least part of the flow comprising carbamate in aqueous solution coming from the specified partition regeneration of urea in the specified partition decomposition;

providing means for feeding the flow comprising ammonia and carbon dioxide in vapour phase obtained in the specified partition decomposition, in the specified reactor for the synthesis of urea;

providing appropriate means for feeding the flow comprising diluted carbamate in aqueous solution obtained in the specified partition decomposition, the gas flow comprising hydrogen, nitrogen and carbon dioxide coming preferably from section reforming of hydrocarbon vapor and a flow comprising ammonia coming from the specified reactor for the synthesis of ammonia, in the specified section of the synthesis of carbamate;

providing means for feeding the flow comprising carbamate in aqueous solution obtained in the specified section of the synthesis of the carbamate in the specified reactor for the synthesis of urea;

providing means for feeding a gaseous flow comprising hydrogen and nitrogen obtained in the mind the way of modernization, which combines the existing installation of ammonia and an existing installation of urea, it becomes possible to obtain a simple and economical manner urea with a high degree of transformation, and at the same time, greatly reduce production costs and energy consumption.

Properties and advantages of the purposes of the invention are presented further in the description of its options, shown below with the help of a non-limiting example with reference to the accompanying drawing.

A brief description of the drawing.

The drawing schematically shows a plant for co-production of urea and ammonia according to the invention, realized or ex novo, or by upgrading an existing installation of ammonia and an existing installation of production of urea conventional type.

A detailed description of the preferred option.

Only to make the description of the present invention easier, the link will be placed on connecting pipes of different parts of the installation, and on the same part of the installation, which is described hereinafter and shown in the drawing, conventional in themselves, only if it is clearly needed.

As for drawing, it is about the CLASS="ptx2">

Primarily installation 1 includes a reactor 2 ammonia, section 3 synthesis of carbamate, section 4 of the synthesis of urea, section 21 of the regeneration of urea and section 23 of the decomposition of the carbamate.

Section 4 of the synthesis of urea includes arranged in series relative to each other reactor 5 synthesis of urea and the stripper 6 high pressure (180 bar) for the partial decomposition of carbamate and allocation of free ammonia in aqueous solution present in the reaction mixture coming from the reactor 5.

As will be seen later, the way co-production of ammonia and urea according to the present invention allows to obtain in the reactor 5 synthesis of urea output, comparable to the yield obtained with plants urea production according to the previously known prior art, i.e. the output is between 62% and 70%.

Example operating conditions of the reactor 5 synthesis of urea used in the present invention is: the molar ratio of NH3/CO2equal to 3.8, the molar ratio of N2O/CO2equal to 0.8, yield 64%, pressure 180 bar, temperature 190oC.

In the example of the drawing part of an installation for the production of urea is the installation of a fully recyclized tee is a specific type of method for the synthesis of urea, but can be advantageously used also in installations that work with the methods of synthesis of urea, for example with partial recycling or type "carried out in one pass without recycling of the reacting substances.

Figures 7, 8, 9a and 9b specifies a pipe for feeding a gas flow comprising hydrogen, nitrogen and carbon dioxide, the flow comprising ammonia, stream comprising water and a flow comprising diluted carbamate in aqueous solution, respectively, in section 3 synthesis of carbamate.

The gas flow comprising hydrogen, nitrogen and carbon dioxide, preferably extends from section 10 of reforming hydrocarbon vapor, including primary reformer and secondary link reforming, not shown in the drawing, which are parts of a conventional type and therefore well-known experts in this field.

In the following description and the subsequent claims, the term "hydrocarbon" refers to typically the crude raw material, which is the source of hydrogen and carbon, such as, for example, methane or a mixture of liquid and/or gaseous hydrocarbons such as natural gas and naphtha.

The gas flow comprising hydrocarbons and water the native pair, which leads to the formation of hydrogen, carbon monoxide and carbon dioxide. Then create conditions for the decomposition proceeded in the secondary stage of reforming, where there is also a gas stream comprising nitrogen (usually air).

Rooms 12, 13 and 14 respectively indicate the section of the flue stream comprising hydrocarbons, section high temperature of transformation and the low-temperature section of reaction for the conversion of carbon monoxide to carbon dioxide.

Sections 12, 13 and 14 are sections of a conventional type and will therefore not be described in more detail in the following description.

For the purposes of the present invention the gas flow comprising hydrogen, nitrogen and carbon dioxide supplied through tube 7 in section 3 of the synthesis of the carbamate can be obtained using any known method, as an alternative to hydrocarbon steam reforming.

The flow comprising ammonia coming out of reactor 2 synthesis of ammonia and served in section 3 through a pipe 8.

According to the example of the drawing is worth nothing that the pipe 8 is directly connected to the reactor 2 synthesis of ammonia with section 3 of the synthesis of the carbamate. Thus, it becomes possible to apply in the sid carbon which is present in section 3, facilitating the synthesis of carbamate.

Mostly, at least part of the water supplied in section 3 synthesis of carbamate in order to achieve absorption of carbon dioxide and its immediate reaction with ammonia, contained in the stream, comprising diluted carbamate in aqueous solution coming through the pipe 9b of section 23 of the decomposition of the carbamate, which will be described in more detail later.

In the example of drawing a predetermined amount of water is also loaded into the section of the synthesis of carbamate through the pipe 9a. Such water or part of it can come from a source outside installation 1 or mainly of section 22 of the concentration of urea.

However, the feed stream comprising water, through the pipe 9a is totally optional and is used mainly to increase the water content inside the section 3 synthesis of carbamate.

Indeed, there is provided, but does not seem variant of the invention, where all water is supplied in section 3 through a pipe 9b and out of the section 23 of the decomposition of the carbamate. According to another variant of the invention, not represented, section 3 of the synthesis of the carbamate is loaded only through the pipe 9b, the additional amount is Preferably about 30-40% of the total amount of water supplied in section 3 synthesis of carbamate, is fed through the pipe 9a and about 60-70% (e.g., 65%) is fed through the pipe 9b.

From section 3 synthesis of carbamate pipes 15 and 16 are branched to flow comprising carbamate in aqueous solution in the reactor 5 synthesis of urea and flow comprising hydrogen and nitrogen in the reactor 2 synthesis of ammonia, respectively.

Before to be fed into the reactor 2 ammonia synthesis gas flow comprising hydrogen and nitrogen, is directed to pass through the pipe 16 section 17 of mechanisatie and in the drying section 18 of conventional type, where the gas flow respectively cleared.

In particular, in section 17 of mechanisatie possible traces of carbon monoxide and/or carbon dioxide are suitable for conversion to methane. In the drying section 18 of the gas flow comprising hydrogen and nitrogen, on the contrary, dehydratases by washing it with liquid ammonia in order to remove possible traces of water.

In accordance with this gas stream comprising ammonia is allowed to enter the pipe 16 through the pipe 19, and then it is served together with a gas flow comprising hydrogen and nitrogen, in the drying section 18, which typically includes a separator gas/liquid.

In smiga, primarily recyclized in section 4 of the synthesis of urea by means of pipes 20 and 15; at the same time, the gas stream that is free of water, comprising hydrogen and nitrogen, is fed into the reactor 2 synthesis of ammonia through the pipe 16.

The operating conditions of pressure and temperature inside the reactor 2 synthesis of ammonia are typical conditions typical installation of ammonia synthesis, a well-known specialists in this field.

In addition, section 4 of the synthesis part of the installation for the production of urea, also includes a section 21 regeneration urea, section 22 of the concentration of urea and mainly section 23 of the decomposition of the carbamate.

In the example of the drawing section 21 of the regeneration of urea is section of the type comprising a reactor 24 for the decomposition of the carbamate with an average pressure (18 bar) and the reactor 25 for the decomposition of the carbamate at low pressure (4 bar) and the distillation column 26 of ammonia.

Section 22 of the concentration of urea includes, in turn, a pair of vacuum devices 27, 28 respectively, and the vacuum unit 29 shown in dotted lines in the drawing.

The reactor 25 synthesis of urea is connected in its lower part and through pipes 15 and 30 with section 3 of the synthesis of the carbamate is a and the reactor 5 synthesis of urea is provided a separator 31 for extraction from the stream, comprising carbamate in aqueous solution, through a pipe 32 possible ash hydrogen and nitrogen.

The reactor 5 is connected also always in its lower part and through the pipe 33 with the stripper 6, from which it follows vapor phase (including ammonia, carbon dioxide and water vapor), which recyclized in the reactor 5 through the pipe 34, and a liquid phase comprising a solution of partially purified urea) which is fed to the apparatus 24 for the decomposition of carbamate section 21 of the regeneration of urea through the pipe 35.

Tube 35 passes through sections 21 and 22 concentration and regeneration of urea, in order to obtain at the outlet of the apparatus 28, the flow of purified urea, which is always sent through the pipe 35 into the devices selection, conventional in themselves and therefore not present.

Number 36 specifies hose vapors, including ammonia, in the vacuum unit 29, where such vapors are condensed according to a well-known method.

The resulting condensates, containing a residual amount of ammonia in aqueous solution, are sent to the section processing of water (not shown) through a pipe 37.

According to the features of the invention, the pipe 9a feed stream comprising water, in clubs is but the drawing).

In this regard, it becomes possible to load the section 3 synthesis of carbamate stream comprising water coming out of the section 22 of the concentration of urea, mainly recyclist, thus, part of the water already present in the installation.

Pairs, including water, ammonia and carbon dioxide obtained in the devices 24 and 25 decomposition of the carbamate, sent after at least partially condensed in the distillation column 26 ammonia, separating essentially pure ammonia from an aqueous solution of carbamate.

The ammonia resulting from the distillation column is condensed and at least partially recyclized in the reactor 5 synthesis of urea through pipes 19 and 30, and in the drying section 18 through a pipe 19 and 16, respectively.

According to a particular preferred feature of the present invention, the flow comprising carbamate in aqueous solution coming from the bottom of the distillation column 26, is sent through the pipe 39 in section 23 of the decomposition of the carbamate. Thus, it turns out, essentially anhydrous stream comprising ammonia and carbon dioxide in vapour phase, which recyclized in the reactor 5 synthesis of urea through pipes 40 and 34, and a very razbavlenie pipe 9b.

Mainly in accordance with the method of joint production of ammonia and urea of this invention, at least part of the flow comprising carbamate in aqueous solution coming out (trumpet 39) section 21 of the regeneration of urea, subjected to partial processing of decomposition, resulting in obtaining a flow comprising ammonia and carbon dioxide in vapour phase and a flow comprising diluted carbamate in aqueous solution. The flow comprising ammonia and carbon dioxide in vapour phase, served as the pipes 40, 34) in the reactor 5 synthesis of urea, while the flow comprising diluted carbamate in aqueous solution together with a gas flow comprising hydrogen, nitrogen and carbon dioxide, and a flow comprising ammonia coming from the reactor 25 synthesis of ammonia, served (pipe 9b, 7 and 8) in section synthesis of carbamate, where ammonia and carbon dioxide interact with obtaining a flow comprising carbamate in aqueous solution, and a gas stream, comprising hydrogen and nitrogen. The flow comprising carbamate in aqueous solution, then served (pipe 15) to the reactor 5 synthesis of urea, while the gas flow comprising hydrogen and nitrogen, is fed (trumpet 16) in the reactor 2 synthesis of ammonia.

Thanks to this izobreteny reactor 5 synthesis of urea, which mainly recyclized in section 3 synthesis of carbamate, thus allowing a simple and efficient way to get the urea with a high degree of conversion.

In other words, the stage of partial decomposition of carbamate provides high flexibility of the method, as it allows you to work even with very large quantities of water in section 3 synthesis of carbamate, without harmful effect on the molar ratio of N2O/CO2in the reactor 5 synthesis of urea, and therefore on the degree of transformation.

According to a specific preferential variant of the present invention, it becomes possible to further decrease molar ratio of N2O/CO2in the reactor 5 synthesis of urea, consistently increasing the degree of transformation, by supplying at least part of the flow comprising carbamate in aqueous solution coming from section 3 to section 23 of the decomposition of the carbamate through the pipe 41 (represented by a dotted line in the drawing), receiving essentially anhydrous stream comprising ammonia and carbon dioxide in vapour phase, which is sent to the reactor 5 synthesis of urea through pipes 40 and 34, and a very dilute flow of carbamate in aqueous solution, which preimushestvennogo ammonia and urea is characterized further by the fact that that at least part of the flow comprising carbamate in aqueous solution coming (pipe 15) of section 3 of the synthesis of carbamate, exposed mainly a part of the processing by decomposition with obtaining a flow comprising ammonia and carbon dioxide in vapour phase and a flow comprising diluted carbamate in aqueous solution, which is sent (pipe 40, 34) in the reactor 5 synthesis of urea, and in section 3 synthesis of carbamate (pipe 9b), respectively.

Mainly depending on the water content in the streams comprising carbamate in aqueous solution coming from sections 3 and 21, a larger or a smaller portion of these flows is directed to section 23 of the decomposition of the carbamate in order to get recyclebank water in section 3 synthesis of carbamate and sent to the reactor 5 synthesis of urea, essentially anhydrous reactive substances.

Partial decomposition of carbamate contained in the stream emerging from section 3 synthesis of carbamate, and in the stream exiting the section 21 of the regeneration of urea, respectively, can take place in two separate devices decomposition or, as shown in the drawing, in the single section 23 of the apparatus of decomposition.

Preferably, the section 23 of the decomposition of the carbamate work the guilt.

According to a particular preferred aspect of the present invention section 3 synthesis of carbamate includes three chambers 42, 43 and 44, separated by two film absorbers 45 and 46.

In the example of the drawing chamber 42-44 and film absorbers 45-46 included inside the unit, essentially, a vertical tubular device.

The first chamber 42 is located in the lower part of the section 3 and is in liquid communication with the pipe 7, the feed gas stream comprising hydrogen, nitrogen and carbon dioxide, in section 3 synthesis of carbamate, and with the pipe 15, the feed stream comprising carbamate in aqueous solution obtained in section 3 for the synthesis of carbamate in the reactor 5 synthesis of urea.

The second chamber 45 is located in the Central part of the section 3 and is in liquid communication with the pipe 8, the feed stream comprising ammonia coming out of the reactor 2 synthesis of ammonia, in section 3 synthesis of carbamate.

The third chamber 44 is located in the upper part of the section 3 and is in liquid communication with the pipes 9a and 9b, a feed stream comprising water and diluted carbamate in aqueous solution in section 3 synthesis of carbamate, and with the pipe 16, a feed gas stream comprising hydrogen and nitrogen obtained in the synthesis reactor AMM is the number of pipes, having opposite ends in fluid communication with the first and second camera.

The second film absorber 46 is located between the second and third chambers 43, 44 and includes a number of tubes having opposite ends in fluid communication with the second and the third camera.

Thanks designed section 3 synthesis of carbamate becomes possible to perform a quick and efficient reaction between the carbamate and carbon dioxide in a structurally simple device of small size, including low implementation cost and low running costs.

The flow comprising diluted carbamate in aqueous solution coming from section 21 of the regeneration of urea, preferably served in the third chamber 44 through the pipe 9b is close to the second film absorber 46.

In addition, particularly satisfactory results have been obtained by supplying the specified flow comprising diluted carbamate in aqueous solution, in the third chamber 44, close to the upper end of the section 3 of the synthesis of the carbamate as shown in the drawing dashed lines.

The same way the stream comprising water is fed into the third chamber 44 through the pipe 9a, close to the upper end of the section 3 economic conditions, includes many horizontal perforated plates of conventional type, which increase the absorptive output.

In accordance with the specific structure of section 3 of the synthesis of carbamate drawing flow comprising hydrogen, nitrogen and carbon dioxide, leaving a section 10 reforming of hydrocarbon vapor, is fed through the pipe 7 into the first chamber 42.

From the chamber 42 the specified thread is forced to enter from the sides of the tubes in the first film absorber 45, where it flows countercurrent flow comprising ammonia and carbamate in aqueous solution leaving the second chamber 43.

In this part, a large part of the carbon dioxide reacts with free ammonia or preferably in the vapor phase or in liquid form, to form a carbamate, which is collected in the chamber 42.

An example of the composition of the flow comprising carbamate in aqueous solution leaving the camera 42, obtained by the method according to the present invention is the following example: ammonia is 37.7 wt.%, carbon dioxide 43,7% wt. and water 19.0 wt.%.

The gas stream leaving the first film absorber 45, is mixed in the chamber 43 with a stream of ammonia leaving the reactor 2 synthesis of ammonia through the pipe 8, and comes from trobbiani solution of ammonia, coming out of the third chamber 44.

The third chamber 44, which is loaded through pipes 9a and 9b stream comprising water coming out of the section 22 of the concentration of urea, and a flow comprising carbamate in aqueous solution coming from section 21 of the regeneration of urea, allowing you to permanently remove residual ammonia and carbon dioxide.

Thanks to the present invention, for example, becomes possible to obtain a gas stream comprising hydrogen and nitrogen coming out of the camera 44 (trumpet 16) having a content of residual ammonia, equal to about 1 mole.%, and the content of residual carbon dioxide, equal to about 0.05 mole.%.

The heat of reaction, which is developed in section 3 synthesis of carbamate, mainly removed through indirect heat exchange with a cooling liquid (e.g. water), which preferably is forced to pass through the side shell in film absorbers 45 and 46.

Thus, it becomes possible to maintain the temperature within section 3 of the synthesis of carbamate within the parameters such that prevent the crystallization of the carbamate in the pipes of the film absorbers 45 and 46.

The optimal values of temperature and pressure within section 3 SinTe the positive 130o(C), respectively.

Escaping gas, enriched with inert substances such as nitrogen and methane leaving the reactor 2 synthesis of ammonia, separated respectively from the reaction gas and washed in the washing section 47 of the stream, including water supplied in section 3 synthesis of carbamate through the pipe 9a. Being washed out, leaving the gas delivered to the regeneration of conventional type (not shown).

In doing so, it becomes possible to regenerate the wash water through the greater part of the ammonia dissolved in the outgoing gas, which is predominantly served in section 3 synthesis of carbamate.

Number 50 is represented here, the cooling apparatus to cool the flow comprising ammonia coming from the synthesis reactor 2 to values lower than about 100oC.

According to a particular preferred aspect of the present invention is provided in the plant for combined production of ammonia and urea means for cooling a gas stream comprising hydrogen, nitrogen and carbon dioxide, through indirect heat exchange with a flow comprising urea in aqueous solution in section 21 of the regeneration of urea.

In castestinformer, forced to pass through the pipe 7 through the devices 24 and 25 decomposition of carbamate section 21 of the regeneration of urea, where it is cooled through indirect heat exchange with a stream of partially purified urea.

Thus, it is mainly the double benefit of cooling, on the one hand, the gas flow emerging from the reforming section 10, will be presented in section 3 synthesis of carbamate and power, on the other hand, the heat necessary for the decomposition of carbamate, is included in the partially purified stream of urea, without the need for external heat sources, which may therefore result in significant savings in terms of energy consumption and operating costs.

According to another aspect of the present invention, the reaction temperature for the synthesis of urea is mainly controlled with the startup of the reactor 5, respectively preheated stream comprising ammonia.

To this end, the installation of combined production of ammonia and urea is further provided means (shown in the drawing, the heat exchanger 48) for pre-heating of the stream, including retalitory ammonia coming through the pipes 29 and 30 of section 21 of the regeneration MoA urea.

If small amounts of ammonia and carbon dioxide are directed into the reactor 5 synthesis of urea, the temperature control of the reaction is no longer (only) with pre-heating flow comprising ammonia and using respectively the cooling flow comprising ammonia and carbon dioxide.

In fact, in this case, the heat required for the reaction of synthesis of urea, is at least partly due to the heat of formation of the carbamate produced inside the reactor 5.

As a consequence, depending on the amount of ammonia and carbon dioxide, filed in the reactor 5, it can be filed with the need for more heat through the heat exchanger 48 or to reduce the heat inside the reactor 5 by removing excess heat.

The latter is usually, if in addition to stripper 6 and section 4 of the synthesis of urea is also provided by section 23 of the decomposition of the carbamate.

In this case, the installation according to the present invention mainly includes a tool (represented in the drawing, the heat exchanger 49) for cooling flow comprising ammonia and carbon dioxide in vapour phase leaving sections of the decomposition of the carbamate (with whom Icewine.

The water stream is preferably used as a coolant so as to produce a regenerative steam on a high heat level, for example 5 bar.

Installation drawing can be a new installation or it can be implemented by upgrading the existing installation for the production of ammonia and existing installations for the production of urea.

According to the present invention a method for the simultaneous upgrade of ammonia synthesis and installing the synthesis of urea, comprising respectively the reactor (2) ammonia synthesis reactor (5) synthesis of urea and section (21) for the regeneration of urea, mainly includes stage software, respectively, of section (3) synthesis of carbamate and section (23) of the decomposition of the carbamate, means for feeding at least part of the flow comprising carbamate in aqueous solution coming from the specified section (21) for the regeneration of urea in the specified partition decomposition, means (40, 34) to flow, comprising ammonia and carbon dioxide in vapour phase obtained in the specified partition decomposition, in the specified reactor (5) synthesis of urea, the corresponding means (9b, 7 and 8) for flow comprising diluted carb carbon preferably coming from a section of the reforming of hydrocarbon vapor and a flow comprising ammonia coming from the specified reactor (2) synthesis of ammonia, specified in section 3 of the synthesis of carbamate, means (15) for feeding the flow comprising carbamate in aqueous solution obtained in the specified section 3 synthesis of carbamate in the specified reactor (5) synthesis of urea, and means (16) for feeding a gas flow comprising hydrogen and nitrogen obtained in the specified section 3 synthesis of carbamate in the specified reactor (2) synthesis of ammonia.

In addition, according to other variants of the above method of modernisation according to the invention are provided principally to sections or means, as described in specific paragraphs 18-22 attached to them.

In the present description and the subsequent claims, the term "means for feeding" are usually referred to various parts of the device, such as, for example, pipes, pumps and compressors, which are used for transporting liquid or gaseous fluid from one part of the plant to another part of the installation.

From the above description clearly derive numerous advantages achieved by the present invention; in particular, obespechivayushchuyu and low operational costs and low energy consumption.

1. The way co-production of ammonia and urea on the installation comprising a reactor for the synthesis of ammonia synthesis reactor urea and the regeneration section of the urea, providing for the reforming of hydrocarbon vapor, receiving stream containing ammonia and carbon dioxide, the interaction of solutions of ammonia and carbon dioxide in the synthesis process of urea and carbamate, characterized in that it comprises the stage of: processing with partial decomposition of at least part of the flow comprising carbamate in aqueous solution coming from the specified partition regeneration of urea, for obtaining a flow comprising ammonia and carbon dioxide in vapour phase and a flow comprising diluted carbamate in aqueous solution; feeding the specified stream comprising ammonia and carbon dioxide in vapor phase in the reactor for the synthesis of urea; feed section synthesis of carbamate flow comprising diluted carbamate in aqueous solution obtained by decomposition of the carbamate, a gas stream that contains hydrogen, nitrogen and carbon dioxide and which is preferably obtained at the stage of reforming of hydrocarbon vapor and a stream containing ammonia from the reactor for the synthesis of ammonia, the interaction of ammonia with the solution and the gas flow, comprising hydrogen and nitrogen; flow comprising carbamate in aqueous solution in the reactor for the synthesis of urea; submission of a specified gas flow comprising hydrogen and nitrogen in the reactor for the synthesis of ammonia.

2. The method according to p. 1, characterized in that the stream exiting the reactor for the synthesis of ammonia, contains ammonia in the vapor phase.

3. The method according to p. 1, characterized in that it further includes a preliminary stage of cooling flow coming from the reforming step, and comprising hydrogen, nitrogen and carbon dioxide by indirect heat exchange of this stream with a stream comprising an aqueous solution of urea from the stage of synthesis of urea decomposition of carbamate in section regeneration of urea.

4. The method according to p. 1, characterized in that it further includes stages: processing with partial decomposition of at least part of the flow comprising carbamate in aqueous solution obtained in section synthesis of carbamate, for obtaining a flow comprising ammonia and carbon dioxide in vapour phase and a flow comprising diluted carbamate in aqueous solution; feeding the specified stream comprising ammonia and carbon dioxide in vapor phase in the reactor for the synthesis of urea; flow comprising diluted ka carbamate, in section synthesis of carbamate.

5. The method according to p. 1, characterized in that it further includes the stage of preliminary heat flow with recycled ammonia, leaving a section of the regeneration of urea, and supply the specified pre-heated stream comprising ammonia, in section synthesis of urea.

6. The method according to p. 1 or 4, characterized in that it further includes stages: cooling flow comprising ammonia and carbon dioxide in vapour phase resulting from stage partial decomposition of carbamate; feeding the cooled stream into the specified reactor for the synthesis of urea.

7. The method according to p. 1, characterized in that it further includes a step of feeding a stream comprising water, leaving sections of the concentration of urea in the specified section of the synthesis of the carbamate.

8. Installation for the combined production of ammonia and urea, containing the reactor 2 synthesis of ammonia, section 3 of the synthesis of the carbamate, the reactor 5 synthesis of urea and section 21 of the regeneration of urea, characterized in that it includes section 23 decomposition of carbamate; means 39 for supplying at least part of the flow comprising carbamate in aqueous solution coming from the specified partition 21 regenerated in the vapor phase, received in the specified section 23 of decomposition in the reactor 5 synthesis of urea; appropriate means 9b, 7 and 8 for a flow comprising diluted carbamate in aqueous solution obtained in the specified section 23 decomposition, the gas flow comprising hydrogen, nitrogen and carbon dioxide, leaving preferably from section 10 reforming of hydrocarbon vapor and a flow comprising ammonia coming from the specified reactor 2 synthesis of ammonia are specified in section 3 of the synthesis of carbamate; a means 15 for feeding the flow comprising carbamate in aqueous solution, received in the specified section 3 synthesis of carbamate in the specified reactor 5 synthesis of urea; means 16 for feeding a gaseous flow comprising hydrogen and nitrogen obtained in the specified section 3 synthesis of carbamate in the specified reactor 2 synthesis of ammonia.

9. Installation under item 8, characterized in that it further includes means 9a for supplying a stream comprising water specified in section 3 of the synthesis of carbamate in liquid connection with section 22 of the concentration of urea.

10. Installation under item 8, characterized in that the specified section 3 synthesis of carbamate includes: the first chamber 42 is in fluid communication with the specified tool 7 to the gas flow, including flow, comprising carbamate in aqueous solution obtained in the specified section 3 synthesis of carbamate in the specified reactor 5 synthesis of urea, respectively; the second chamber 43 in fluid communication with the specified means 8 for feeding the flow comprising ammonia coming from the specified reactor 2 synthesis of ammonia, specified in section 3 of the synthesis of carbamate; a third chamber 44 in fluid communication with the specified means 9b for flow comprising diluted carbamate in aqueous solution, specified in section 3 of the synthesis of carbamate, and with the specified means 16 for feeding a gas flow comprising hydrogen and nitrogen, received in the specified section 3 synthesis of carbamate in the specified reactor 2 synthesis of ammonia, respectively; the first film absorber 45, located between the said first and the second chambers 42, 43 and includes many pipe having opposite ends in fluid communication with the specified first, respectively the specified second chambers 42, 43; the second film absorber 46, located between the said second and the third chambers 43, 44 and includes many pipe having opposite ends in fluid communication with the specified second, respectively identified third chambers 43, 44.

11. Huila flow, including the water coming out of the section 22 of the concentration of urea.

12. Installation according to p. 10, characterized in that the camera 42-44 and these absorbers 45-46 included in a single, essentially, a vertical tubular device, the first chamber 42 and the third chamber 44 which are respectively in the lower and upper ends of the specified device.

13. Installation under item 8, characterized in that the means 8 for feeding the flow comprising ammonia, directly connects the specified reactor 2 synthesis of ammonia with the specified session 3 synthesis of carbamate.

14. Installation under item 8, characterized in that it further includes means 24, 25 for cooling the specified stream comprising hydrogen, nitrogen and carbon dioxide, through indirect heat exchange with a flow comprising urea in aqueous solution in the specified section 21 of the regeneration of urea.

15. Installation under item 8, characterized in that it additionally includes means 41 for supplying at least part of the flow comprising carbamate in aqueous solution coming from the specified partition 3 synthesis of carbamate in the specified section 23 of the decomposition of the carbamate.

16. Installation under item 8, characterized in that the IAK, coming out of the section 22 of the regeneration of urea, and a means 30 for filing specified in the heated stream comprising ammonia, in the specified reactor 5 synthesis of urea.

17. Installation on p. 8 or 15, characterized in that it further includes means 49 for cooling the specified stream comprising ammonia and carbon dioxide in vapour phase leaving the specified section 23 section decomposition of carbamate; means 34 for supplying a specified cooled stream into the specified reactor 5 synthesis of urea.

18. The method of simultaneous upgrade of ammonia synthesis and installing the synthesis of urea, containing, respectively, the reactor 2 synthesis of ammonia and the reactor 5 synthesis of urea, and section 21 of the regeneration of urea and section 3 of the synthesis of carbamate, characterized in that it includes: the provision of section 23 of the decomposition of carbamate; providing means 39 for supplying at least part of the flow comprising carbamate in aqueous solution coming from the specified section 21 of the regeneration of urea in the specified section 23 of decomposition; the securing means 40, 34 to flow, comprising ammonia and carbon dioxide in vapour phase obtained in the specified section 23 decomposition in the specified reactor 5 SinTe is in aqueous solution, received in the specified section 23 decomposition, the gas flow comprising hydrogen, nitrogen and carbon dioxide, preferably leaving section 10 reforming of hydrocarbon vapor and a flow comprising ammonia coming from the specified reactor 2 synthesis of ammonia are specified in section 3 of the synthesis of carbamate; providing means 15 for feeding the flow comprising carbamate in aqueous solution obtained in the specified section 3 synthesis of carbamate in the specified reactor 5 synthesis of urea; providing means 16 for feeding a gas flow comprising hydrogen and nitrogen, received in the specified section 3 synthesis of carbamate in the specified reactor 2 synthesis of ammonia.

19. The way of modernization under item 18, characterized in that said section synthesis of carbamate include the first chamber 42 is in fluid communication with the specified means 7 for feeding a gas flow comprising hydrogen, nitrogen and carbon dioxide, specified in section 3 of the synthesis of carbamate, and with the specified tool 15, for a flow comprising carbamate in aqueous solution obtained in the specified section 3 synthesis of carbamate in the specified reactor 5 synthesis of urea, respectively; the second chamber 43 in fluid communication with the specified tool 8 for flow, vluu chamber 44 in fluid communication with the specified means 9b for flow, comprising diluted carbamate in aqueous solution, specified in section 3 of the synthesis of carbamate, and with the specified means 16 for feeding a gas flow comprising hydrogen and nitrogen obtained in the specified section 3 synthesis of carbamate in the specified reactor 2 synthesis of ammonia, respectively; the first film absorber 45, located between the said first and the second camera 42, 43 and includes many pipe having opposite ends in fluid communication with the specified first, respectively the specified second chambers 42, 43; the second film absorber 46, located between the said second and the third chambers 43, 44 and includes many pipe having opposite ends in fluid communication with the specified second, respectively identified third chambers 43, 44.

20. The way of modernization under item 18, characterized in that it also encompasses the provision of means 24, 25 for cooling the specified stream comprising hydrogen, nitrogen and carbon dioxide, through indirect heat exchange with a flow comprising urea in aqueous solution in the specified section 21 of the regeneration of urea.

21. The way of modernization under item 18, characterized in that it also encompasses obespecheniya from the specified partition 3 synthesis of carbamate in the specified section 23 of the decomposition of the carbamate.

22. The way of modernization under item 18, characterized in that it also encompasses the provision of means 48 for pre-heating of the stream, including retalitory ammonia coming out of the section 22 of the regeneration of urea; the provision of means 30 for filing specified in the heated stream comprising ammonia, in the specified reactor 5 synthesis of urea.

23. The way of modernization under item 18, characterized in that it also encompasses: securing means 49 for cooling the specified stream comprising ammonia and carbon dioxide in vapour phase leaving the specified section 23 decomposition of carbamate; providing means 34 for feeding the cooled stream into the specified reactor 5 synthesis of urea.

 

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