Abstract: A method for producing carbamate including a urea production step; a carbamate-forming step; an ammonia separation step of absorbing the gas with water in the presence of carbonate to produce a gas absorption water, and separating ammonia; an aqueous alcohol solution separation step of separating an aqueous alcohol solution from the gas absorption water; an ammonia/carbon dioxide separation step of separating carbon dioxide gas from the aqueous ammonia solution in the gas absorption water from which the aqueous alcohol solution is separated; an aqueous ammonia solution reusing step of mixing the aqueous ammonia solution and carbonate with the water to be used for production of the gas absorption water.

Abstract: Method for the production of urea from ammonia and carbon dioxide in a urea plant containing a high-pressure synthesis section with a horizontal pool condenser, wherein the method comprises exchanging heat from a high pressure process medium received in a shell section of the pool condenser to a medium pressure urea containing solution received in a first heat exchanging section provided in the pool condenser to at least decompose ammonium carbamate into NH3 and CO2, wherein the method further comprises exchanging heat from the high pressure process medium to a low pressure steam condensate received in a second heat exchanging section provided in the pool condenser to produce low pressure steam. The invention also relates to an apparatus for the production of urea from ammonia and carbon dioxide.

Abstract: A process for the direct synthesis of urea from ammonia and carbon dioxide with increased corrosion resistance, comprising, in the high-pressure synthesis section, a reaction step in a vertical reactor fed with at least one stream of fresh carbon dioxide containing a passivating agent and a decomposition-stripping step of the non-converted reagents, wherein the gas-liquid mixture collected at the head of the reactor is separated into a gaseous stream and a liquid stream fed to the tail and head of the stripper, respectively.

Abstract: A process for synthesis of urea and a related reaction section of a urea plant, where: ammonia and carbon dioxide are reacted in a liquid phase in a first reaction zone (S1) and heat (Q1) is withdrawn from said first reaction zone to promote the formation of ammonium carbamate, the liquid product (103) from said first reaction zone is then passed to a second reaction zone (S2) distinguished from said first reaction zone, and heat (Q2) is added to said second reaction zone to promote the decomposition of ammonium carbamate into urea and water, where the liquid phase in at least one of said first reaction zone and second reaction zone is kept in a stirred condition. A downflow reactor for carrying out the above process is also disclosed.

Abstract: Plant for urea production from ammonia and carbon dioxide having a so-called high-pressure section which comprises a synthesis reactor and a condensation unit (7, 107) positioned inside the reactor, all substantially operating at the same pressure.

Abstract: A method and apparatus is provided for cleaning flue gases from combustion plants. The method includes removing dust and removing nitrogen from flue gases, bringing flue gases into contact with an aqueous ammonia solution in the presence of an oxidizing agent whereby a reaction solution forms which contains at least ammonium carbonate, heating the reaction solution such that ammonium carbonate decomposes and carbon dioxide and ammonia transfer into the gas atmosphere, and reacting the gaseous carbon dioxide and the gaseous ammonia to form urea. The apparatus includes a device for removing nitrogen and removing dust from the flue gases, a washing device downstream of the device for removing nitrogen and removing dust, a stripper downstream of the washing device, and a urea installation downstream of the stripper.

Abstract: Methods for producing urea are provided. A method for producing urea can include exchanging heat from a syngas comprising hydrogen and carbon dioxide to a urea solution comprising urea and ammonium carbamate. The heat transferred can be sufficient to decompose at least a portion of the ammonium carbamate. In one or more embodiments, the syngas can be reacted with liquid ammonia to provide a carbon dioxide lean syngas and an ammonium carbamate solution. The ammonium carbamate solution can be heated to a temperature of about 180 C. or more. At least a portion of the ammonium carbamate in the heated ammonium carbamate solution can be dehydrated to provide the urea solution.

Abstract: Process for increasing the capacity of an existing urea plant comprising a high-pressure urea synthesis section and one or more recovery sections, wherein next to the existing urea plant a urea production unit, comprising a high-pressure urea synthesis section and a medium-pressure recovery section, is installed, wherein a urea-containing stream is produced from ammonia and carbon dioxide and the urea-containing stream is sent to the existing urea plant where the urea-containing stream is further purified in the low-pressure recovery section.

Abstract: A process for producing urea is disclosed, wherein liquid ammonia and carbon dioxide are reacted in a high-pressure synthesis section (100), and at least part of the carbon dioxide is fed to said synthesis section (100) in liquid phase. A plant operating according to said process and a method for modernizing existing plants accordingly are also disclosed.

Abstract: Process for the preparation of urea from ammonia and carbon dioxide in a urea production process comprising, in a high-pressure synthesis section: a. a reactor, wherein ammonia and carbon dioxide react to form a urea-comprising synthesis solution; b. a stripper, wherein the urea-comprising synthesis solution is heated and stripped, optionally in counter-current with a stripping agent; c. a submerged condenser, wherein the gas leaving the top of the stripper is, at least partially, condensed to form a condensate solution and d. an ejector, in the line connecting the submerged condenser and the reactor, supporting the transport of the condensate solution from the submerged condenser to the reactor, wherein a gas stream leaving the top of the submerged condenser is controlled by one or more controlling elements.

Abstract: A process for producing urea is disclosed, wherein liquid ammonia and carbon dioxide are reacted in a high-pressure synthesis section (100), and at least part of the carbon dioxide is fed to said synthesis section (100) in liquid phase. A plant operating according to said process and a method for modernizing existing plants accordingly are also disclosed.

Abstract: A method for revamping a conventional self-stripping urea plant is disclosed, where a minor portion (18a) of the carbon dioxide feed is fed to the stripper (7) and used as a stripping agent. In further embodiments, another carbamate condenser is installed, or the conventional horizontal shell-and-tube carbamate condenser (6) is replaced with a vertical submerged unit.

Abstract: Process for the production of urea from ammonia and carbon dioxide in a urea plant containing a high-pressure synthesis section comprising two reactor sections, a stripper and a condenser, and a recovery section, wherein in the first reactor section a first synthesis solution is formed that is fed to the second reactor section; fresh carbon dioxide is fed to the second reactor section and in the second reactor section a second synthesis solution is formed that is fed to the stripper, wherein the second synthesis solution is stripped with the use of carbon dioxide as stripping gas and the mixed gas stream obtained in the stripper is sent to the condenser together with fresh ammonia and a carbamate stream, whereafter the condensate that is formed in the condenser is fed to the first reactor section and the urea stream that is obtained in the stripper is further purified in the recovery section, wherein the flow of the first synthesis solution from the first reactor section to the second reactor section, the flo

Abstract: A process and a related plant layout for producing urea are disclosed, wherein the high-pressure loop (1) comprises a synthesis reactor (2), a thermal stripper (3), a condenser (4), and an adiabatic CO2 stripper (10) disposed upstream said thermal stripper, separating a vapour phase (13) containing ammonia from the urea solution (9) discharged from the reactor, and recycling said vapour phase to the reactor. The adiabatic stripper (10) can be incorporated in a reactor (200) having a top reaction zone and a bottom adiabatic stripping zone. A revamping method for a conventional urea plant in accordance with the inventive process is also disclosed.

Abstract: An enhanced process is described for the synthesis of urea from ammonia and carbon dioxide, at a high pressure and temperature, with the formation of ammonium carbamate as intermediate, which includes a high pressure synthesis section, comprising at least one separation step by decomposition-stripping with ammonia of the non-converted ammonium carbamate, carried out in a vertical apparatus, commonly called stripper, characterized in that said step also comprises a feeding, in the lower part of said stripper, of a stream of CO2, heated to a temperature ranging from 130 to 230° C., in a quantity of 1 to 15% by weight with respect to the total weight of the fresh CO2 fed to the process, containing a passivating agent in such a quantity that its equivalent content of O2 in moles varies from 0.05% to 0.80% with respect to the moles of CO2 of said stream.

Abstract: A method and apparatus is provided for cleaning flue gases from combustion plants. The method includes removing dust and removing nitrogen from flue gases, bringing flue gases into contact with an aqueous ammonia solution in the presence of an oxidizing agent whereby a reaction solution forms which contains at least ammonium carbonate, heating the reaction solution such that ammonium carbonate decomposes and carbon dioxide and ammonia transfer into the gas atmosphere, and reacting the gaseous carbon dioxide and the gaseous ammonia to form urea. The apparatus includes a device for removing nitrogen and removing dust from the flue gases, a washing device downstream of the device for removing nitrogen and removing dust, a stripper downstream of the washing device, and a urea installation downstream of the stripper.

Abstract: A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the steps of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section and of using at least a part of the condensed steam, obtained by indirect thermal exchange with a second part of said aqueous solution comprising urea, ammonium carbmate and ammonia in a high-pressure stripping unit, as a heating fluid for the dissociation of the first part of the aqueous solution comprising urea, ammonium carbmate and ammonia in the medium-pressure treatment section.

Abstract: A method for co-producing electric power and urea from carbonaceous fuels such as coal, by pyrolizing the coal with oxygen to produce a raw rich gas and a hot char which is gasified with air to produce a raw lean gas. Subsequent to the cleaning of the two gases, the cleaned rich gas is made up of CO and 2H2, and the clean lean gas is made up of N2+CO. The CO in the rich gas is separated from the 2H2 and is added to the lean gas to enrich it with CO to become a lean fuel gas which fuels a gas turbine and is part of a combined cycle system which efficiently generates electric power while exhausting an off-gas (flue gas) made up of N2+CO2. The 2H2 separated from the CO, and the N2+CO2 of the exhausted flue gas are together synthesized to produce urea —CO(NH2)2.

Abstract: An enhanced process is described for the synthesis of urea from ammonia and carbon dioxide, at a high pressure and temperature, with the formation of ammonium carbamate as intermediate, which includes a high pressure synthesis section, comprising at least one separation step by decomposition-stripping with ammonia of the non-converted ammonium carbamate, carried out in a vertical apparatus, commonly called stripper, characterized in that said step also comprises a feeding, in the lower part of said stripper, of a stream of CO2, heated to a temperature ranging from 130 to 230° C., in a quantity of 1 to 15% by weight with respect to the total weight of the fresh CO2 fed to the process, containing a passivating agent in such a quantity that its equivalent content of O2 in moles varies from 0.05% to 0.80% with respect to the moles of CO2 of said stream.

Abstract: A process for urea production comprises a first process step in which ammonia (7) and carbon dioxide (6) are obtained, subjecting natural gas (1) to reforming treatments (12, 14), and a second step of urea (8a) production from such ammonia (7) and from carbon dioxide, through a formation of a solution comprising urea and ammonium carbamate in a urea synthesis reactor (20) and a subsequent decomposition of the ammonium carbamate and. urea recovery, the process comprises the steps of:—treating combustion smokes (5) comprising carbon dioxide with an aqueous solution (9a) comprising a part (7b) of such ammonia (7), obtaining an aqueous ammonium carbamate solution (9c);—supplying the solution (9c) thus obtained to the second process step.

Abstract: Disclosed is a method for the production of urea from natural gas, wherein a) natural gas undergoes partial oxidation or autothermal reformation with a gas containing oxygen in a first step and the raw synthesis gas thus arising, consisting essentially of carbon monoxide, carbon dioxide, methane and hydrogen, can be transformed by catalytic conversion of CO and H2O to form CO2 and H2, whereupon carbon monoxide and methane are removed in a multistep gas cleaning process and the hydrogen is converted into ammonia upon addition of nitrogen, and subsequently, b) the ammonia is recombined with the previously separated carbon dioxide in a second step and the ammonia is thus fully converted into urea.

Abstract: A method for modernizing a urea production plant including a urea synthesis reactor, a stripping unit and at least one condensation unit. The method includes providing: means in the condensation unit for substantially condensing at least a portion of a flow comprising ammonia and carbon dioxide in vapor phase leaving the stripping unit; a second stripping unit; means for feeding a first portion of a reaction mixture flow comprising urea, carbamate and free ammonia in aqueous solution leaving the reactor to the first stripping unit; means for feeding a second portion of the reaction mixture flow leaving the reactor to the second stripping unit; and means for feeding at least a portion of a flow comprising ammonia and carbon dioxide in vapor phase leaving the second stripping unit directly to the synthesis reactor. A de-bottlenecking of the high-pressure section downstream of the synthesis reactor may be achieved, improving production capacity.

Abstract: Systems and methods for producing urea are provided. A method for producing urea can include exchanging heat from a syngas comprising hydrogen and carbon dioxide to a urea solution comprising urea and ammonium carbamate. The heat transferred can be sufficient to decompose at least a portion of the ammonium carbamate. In one or more embodiments, the syngas can be reacted with liquid ammonia to provide a carbon dioxide lean syngas and an ammonium carbamate solution. The ammonium carbamate solution can be heated to a temperature of about 180° C. or more. At least a portion of the ammonium carbamate in the heated ammonium carbamate solution can be dehydrated to provide the urea solution.

Abstract: The invention relates to a process for the preparation of urea from ammonia and carbon dioxide in a urea plant that contains a high-pressure synthesis section and one or more recovery section(s) at a lower pressure, the high-pressure synthesis section comprising a reactor, a stripper and a condenser, with gases leaving the high-pressure synthesis section being condensed in a medium-pressure condenser at 0.5-12 MPa to which also a carbamate stream from one of the recovery sections is supplied, after which at least a part of the formed condensate is supplied to the high-pressure condenser.

Abstract: A method for revamping a urea plant of the type comprising a synthesis section (2) having a urea synthesis reactor (5), a thermal stripping unit (7) and at least one horizontal condensation unit (6), a treatment section (3) operating at medium pressure and a recovery section (4) operating at low pressure foresees the transformation of said at least one horizontal condensation unit (6) into a vertical condensation unit of the submerged type comprising a tube bundle and the provision of means (37, 41) for feeding a flow comprising ammonia and carbon dioxide in vapor phase and a flow of condensation liquid comprising carbamate simultaneously and independently in each of the tubes of said tube bundle with circulation inside said tubes in equicurrent from the bottom towards the top, and means (39, 50) for feeding at least one part of the feed carbon dioxide into said stripping unit (7) for use as stripping agent.

Abstract: A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the step of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section.

Abstract: It is intended to enable an apparatus for synthesizing urea and a method for revamping the same to place a heavy condenser at a relatively low position and to circumvent problems associated with letting a process fluid flow within a tube in the condenser. The present invention provides an apparatus for synthesizing urea including: a synthesis reactor for reacting NH3 with CO2 to obtain a urea synthesis solution containing urea, unreacted NH3 and CO2, and water; a stripper for stripping the urea synthesis solution with use of at least a part of raw material CO2 to separate a gas containing the unreacted NH3 and CO2; a vertical submerged condenser having a shell and tube structure for condensing the gas in an absorbing medium on the shell side while cooling the gas with a cooling medium passing through the tube side; and recycling means for recycling a liquid obtained from this condenser to the synthesis reactor, wherein this condenser is placed below the synthesis reactor.

Abstract: It is intended to enable more smooth operation in an apparatus for synthesizing urea by circumventing the downward flow of a urea synthesis solution which is a gas-liquid two-phase flow and stabilizing the flow of the urea synthesis solution still remaining the gas-liquid two-phase flow and to reduce energy loss by giving smaller flow resistance.

Abstract: A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the step of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section.

Abstract: In a process and an apparatus for synthesizing urea which synthesize urea from ammonia and carbon dioxide, the operating condition can be grasped easily and with good accuracy. A process for synthesizing urea which includes: a reaction step of obtaining a urea synthesis solution which contains urea, unreacted ammonia, unreacted carbon dioxide and water by causing ammonia and carbon dioxide to react with each other; a stripping step of separating a gas mixture containing the unreacted ammonia and the unreacted carbon dioxide by stripping the urea synthesis solution by using at least a portion of raw material carbon dioxide; a condensing step of obtaining a condensed liquid by condensing the gas mixture in an absorbing medium while cooling the gas mixture; a recycling step of recycling the condensed liquid to the reaction step; and a step of measuring the density of the condensed liquid online. An apparatus for carrying out this process is provided.

Abstract: In a process for urea production of the type comprising the reaction between ammonia and carbon dioxide in a high-pressure reactor followed by an autothermal stripping of the resulting reaction mixture so as to obtain a gaseous flow comprising ammonia and carbon dioxide and a liquid flow comprising urea and residual carbamate in aqueous solution and by a stripping of said gaseous flow in units operating at medium pressure, a gaseous flow coming from said units operating at medium pressure and comprising ammonia and carbon dioxide is partially condensed in a condenser to give a mixed liquid/gaseous flow. The uncondensed gases comprising ammonia and carbon dioxide are separated from the liquid phase in a separator and subjected to washing in a packed portion of a column in countercurrent with a flow of a carbonate solution obtaining a gaseous flow essentially consisting of ammonia and a liquid flow comprising a carbamate solution in which the carbon dioxide contained in said uncondensed gases has been absorbed.

Abstract: Process for increasing the capacity of a urea plant comprising a compression section, a high-pressure synthesis section, a urea recovery section, in which a urea melt is formed, and optionally a granulation section, the capacity of the urea plant being increased by the additional installation of a melamine plant and the urea melt from the urea recovery section of the urea plant being fed wholly or partly to the melamine plant and the residual gases from the melamine plant being returned wholly or partly to the high-pressure synthesis section and/or the urea recovery section of the urea plant.

Abstract: A process for urea production comprises the steps of:—performing a reaction between ammonia and carbon dioxide in a reaction space to obtain a reaction mixture comprising urea, carbamate and free ammonia in aqueous solution,—subjecting said mixture to a stripping treatment with carbon dioxide feed as a stripping agent to obtain a first flow comprising ammonia and carbon dioxide in vapor phase and a flow comprising urea and residual carbamate in aqueous solution,—feeding said flow comprising urea and residual carbamate in aqueoue solution to a urea recovery section,—separating in said recovery section said residual carbamate from the urea to obtain a first flow of carbamate in aqueous solution.

Abstract: Urea is prepared by reacting ammonia and carbon dioxide in an apparatus comprising a vertical condensation and synthesis column and a stripper, to provide a urea synthesis solution comprising urea, unreacted ammonia, unreacted carbon dioxide and water. The urea synthesis solution is transferred from the top of the vertical condensation and synthesis column to the top of a stripper. Carbon dioxide is introduced into the bottom of the stripper and contacted with the urea synthesis solution, thereby separating the unreacted ammonia and the unreacted carbon dioxide from the urea, and providing a mixed gas comprising ammonia, carbon dioxide and water. The mixed gas is transferred into the bottom of the vertical condensation and synthesis column, where it is reacted with liquid ammonia injected into the bottom and a middle of the vertical condensation and synthesis column. The mixed gas and liquid ammonia are condensed and react to form urea.

Abstract: The invention relates to a process for the preparation of urea from ammonia and carbon dioxide with the application of a synthesis reactor, a condenser, a scrubber and a stripper, wherein an outlet of the stripper, through which a gas stream is discharged during operation, is functionally connected to the inlet of the condenser and to the inlet of the reactor and wherein an outlet of the condenser is functionally connected to an inlet of the scrubber and wherein the obtained reaction mixture is stripped in the stripper in countercurrent with one of the starting materials, wherein the division of the gas stream from the stripper to the condenser and the reactor is completely or partly controlled by one or more controlling elements present in the non-common part of the functional connection between the outlet of the stripper and the inlet of the condenser and/or the inlet of the reactor.

Abstract: The invention relates to a process for the preparation of urea from ammonia and carbon dioxide, which preparation takes places wholy or partly with the application of a synthesis reactor, a condenser, a scrubber and a stripper, wherein an outlet of the stripper, through which a gas stream is discharged during operation, is functionally connected to the inlet of the condenser and to the inlet of the reactor and wherein an outlet of the condenser is functionally connected to an inlet of the scrubber and wherein the obtained reaction mixture is stripped in the stripper in countercurrent with one of the starting materials, wherein the gas stream coming from the top of the submerged condenser is subjected to an extra washing step before this gas stream is supplied to the high-pressure scrubber. The submerged condenser operating as such may be for example a submerged condenser of horizontal or vertical design of a falling-film high-pressure carbamate condenser transformed into a submerged condenser.

Abstract: A method for the production of synthesis urea from liquid ammonia and gaseous carbon dioxide, comprising the step of feeding separate flows (6, 8) of liquid ammonia and gaseous carbon dioxide in continuous to a substantially vertical or horizontal column synthesis reactor (1), is distinguished in that the feed of liquid ammonia is split up into at least two consecutive sections (Z1-Z7) of said column.

Abstract: Process for the preparation of urea from ammonia and carbon dioxide in which all or part of the liquid ammonia needed for the process is supplied to the high-pressure scrubber in such a way that it is in direct contact with the other streams supplied to this scrubber. In particular in such a way that there is direct contact between the liquid ammonia and the off-gases transferred to the high-pressure scrubber from the urea synthesis reactor. More in particular in such a way that there is direct contact between the liquid ammonia and the off-gases transferred to the high-pressure scrubber from the urea reactor and with the carbamate stream, which is transferred from the low-pressure urea recovery section.

Abstract: Process for the preparation of urea from ammonia and carbon dioxide in which a urea synthesis solution containing urea, ammonium carbamate and unconverted ammonia is formed in a synthesis zone, a part of the urea synthesis solution being transferred from the synthesis zone to a medium-pressure treatment zone operating at a pressure of 1-4 MPa, and a gas stream from the medium-pressure treatment zone being absorbed into the low-pressure ammonium carbamate solution from the urea recovery section.

Abstract: The invention relates to a process for the preparation of urea from ammonia and carbon dioxide in which the low-pressure carbamate stream formed in the further upgrading of the urea synthesis solution is stripped in a CO2-carbamate stripper in countercurrent contact with CO2, which results in the formation of a gas mixture consisting substantially of ammonia and carbon dioxide. This gas mixture is preferably subsequently condensed in a high-pressure carbamate condenser and then returned to the synthesis zone.

Abstract: A method for the modernization of a plant for urea production of the type comprising a reactor (2) for urea synthesis, a stripping unit (3) with carbon dioxide and at least one vertical condensation unit (4) of the film type, foresees the provision of means (36) for feeding a major portion of a flow comprising ammonia and carbon dioxide in vapor phase leaving the stripping unit (3) to the condensation unit (4) and the provision in said condensation unit (4) of means (37) for subjecting to substantially total condensation such major portion of the flow comprising ammonia and carbon dioxide in vapour phase, obtaining a flow comprising urea and carbamate in aqueous solution, then fed to the reactor (2) for urea synthesis. Thanks to the present method of modernisation, the efficiency of the condensation unit (4) is remarkably improved, thus permitting an increase of its capacity.

Abstract: A process for the combined production of ammonia and urea of the type comprising an ammonia synthesis reactor (2), a urea synthesis reactor (5) and a urea recovery section (21) stands out for the fact of submitting at least a part of a flow comprising carbamate in aqueous solution coming from the urea recovery section (21) to a partial decomposition treatment, to obtain a flow comprising ammonia and carbon dioxide in vapor phase and a flow comprising diluted carbamate in aqueous solution, which is fed together with a gas flow comprising hydrogen, nitrogen and carbon dioxide, preferably obtained by hydrocarbons steam reforming, and a flow comprising ammonia coming from the ammonia synthesis reactor (2) to a carbamate synthesis section (3), where ammonia and carbon dioxide are caused to react, to obtain a flow comprising carbamate in aqueous solution and a gas flow comprising hydrogen and nitrogen.

Abstract: The invention relates to an installation for the preparation of urea from ammonia and carbon dioxide, the installation comprising two reactor sections in a vertically placed combined reactor and a high-pressure condenser section. The installation may comprise a vertically placed combined reactor, with the two reactor sections being separated by a high-pressure condenser section. In another embodiment the installation comprises a vertically placed combined reactor that comprises two reactor sections and a high-pressure condenser section placed outside the reactor. The invention also relates to a process for the preparation of urea in this installation. This involves feeding the gas stream leaving the stripper wholly or partly to the high-pressure condenser section of the installation. Preferably, a portion of the gas stream leaving the scrubber is fed to the second reactor section in the vertically placed combined reactor via an ammonia-driven ejector.

Abstract: In a process for decomposing a carbamate aqueous solution coming from a urea recovery section of a urea production plant at a predetermined temperature by indirect heat exchange with a heating fluid having a different predetermined temperature, the temperature difference between said carbamate aqueous solution and said heating fluid is reduced to a value not higher than 70° C.

Abstract: A process for urea production in a synthesis loop based on CO2 stripping is distinguished by the fact that at least part of a flow recycle carbamate is sent to a treatment of carbamate decomposition and removal of free ammonia to obtain a vapour flow containing CO2 and NH3 with minimum content of water, and a weak water carbamate solution sent back to a urea recovery unit URS and being at least part of above vapour flow containing CO2 and NH3 with minimum content of water directly fed to the bottom zone of a reaction space.

Abstract: A method for the preparation of urea in a reactor using ammonia and carbon dioxide as starting materials, includes a) bringing the ammonia and carbon dioxide into contact in the reactor under conditions for the formation of carbamate; and b) decomposing the carbamate thus formed to give urea and water. The water formed during step b) is removed from the reaction mixture by a water-selective membrane which is preferably a pervaporation membrane, such as a porous ceramic membrane. Furthermore, a pressure difference is preferably maintained or applied over the selective membrane. The method can in particular be carried out in liquid circulating stream which, in addition to the reactants fed to the circulating stream and the carbamate formed in step a), also contains at least some of the water formed in step b) and also the urea formed in step b), the urea being recovered from the circulating stream and the circulating stream being recycled to the reactor.

Abstract: A process for the synthesis of urea, which comprises subjecting a urea synthesis solution from a urea synthesis column to stripping with a raw material carbon dioxide under a pressure approximately equal to the urea synthesis pressure to separate a major portion of unreacted ammonia and carbon dioxide as a mixed gas from the urea synthesis solution, condensing the mixed gas by indirect heat exchange with the urea synthesis solution from which the mixed gas was separated and that is preferably decompressed to a pressure lower than the urea synthesis pressure, and heating the urea synthesis solution by heat of condensation generated at the time of the condensation of the mixed gas.

Abstract: Urea is prepared by reacting ammonia and carbon dioxide in an apparatus comprising a vertical condensation and synthesis column and a stripper, to provide a urea synthesis solution comprising urea, unreacted ammonia, unreacted carbon dioxide and water. The urea synthesis solution is transferred from the top of the vertical condensation and synthesis column to the top of a stripper. Carbon dioxide is introduced into the bottom of the stripper and contacted with the urea synthesis solution, thereby separating the unreacted ammonia and the unreacted carbon dioxide from the urea, and providing a mixed gas comprising ammonia, carbon dioxide and water. The mixed gas is transferred into the bottom of the vertical condensation and synthesis column, where it is reacted with liquid ammonia injected into the bottom and a middle of the vertical condensation and synthesis column.

Abstract: A process for urea production in a synthesis loop based on CO2 stripping is distinguished by the fact that at least part of a flow recycle carbamate is sent to a treatment of carbamate decomposition and removal of free ammonia to obtain a vapour flow containing CO2 and NH3 with minimum content of water, and a weak water carbamate solution sent back to a urea recovery unit URS and being at least part of above vapour flow containing CO2 and NH3 with minimum content of water directly fed to the bottom zone of a reaction space.

Abstract: The present invention involves a process for the co-production of ammonia and urea in which two parallel gasifiers are utilized so as to optimize the H2/CO2 ratio in the combined syngas product, thereby maximizing the ammonia and urea production. In a first gasifier, solid and/or liquid hydrocarbon materials are partially oxidized in the presence of an oxygen-rich gas in the presence of a temperature moderator, thereby generating a first synthesis gas mixture comprising carbon monoxide, hydrogen and carbon dioxide. In a second gasifier, natural gas is partially oxidized in the presence of an oxygen-rich gas, thereby generating a first synthesis gas mixture comprising carbon monoxide, hydrogen and carbon dioxide. Because natural gas has a lower C/H ratio than the solid and/or liquid hydrocarbon materials, insufficient CO2 is produced in the natural gas gasifier for urea production when only natural gas is used to produce syngas.