Abstract: A process for synthesis of urea from CO2 and NH3 wherein a steam flow (13) produced in the condenser (3) of a high-pressure synthesis loop is compressed to raise its pressure and temperature before using the steam as a heat source for a downstream step of the process.

Abstract: Disclosed is an ethylene and/or propylene cracker unit that uses recycled carbon dioxide as a working fluid. A boiler may also use recycled carbon dioxide as a working fluid. In either instance, instead of releasing high-purity CO2 into the atmosphere, the bulk of the CO2 is utilized as the working fluid and the produced CO2 is captured and sent to the pipeline for utilization or storage. These systems will minimize heat loss and achieve essentially zero CO2 emission to the air.

Abstract: A process for the production of formaldehyde-stabilised urea is described comprising the steps of: (a) generating a synthesis gas; (b) subjecting the synthesis gas to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas; (c) cooling the shifted gas to below the dew point and recovering condensate to form a dried shifted gas; (d) recovering carbon dioxide from the dried shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas; (e) synthesising methanol from the carbon dioxide-depleted synthesis gas in a methanol synthesis unit and recovering the methanol and a methanol synthesis off-gas; (f) subjecting at least a portion of the recovered methanol to oxidation with air to form formaldehyde in a stabiliser production unit; (g) subjecting the methanol synthesis off-gas to methanation in a methanation reactor containing a methanation catalyst to form an ammonia synthesis gas; (h) synthesising ammonia from the ammonia synthesis gas i

Abstract: Systems and methods are provided for producing high quality synthesis gas from a fluidized coking system that includes an integrated gasifier. Additionally or alternately, systems and methods are provided for integrating a fluidized coking process, a coke gasification process, and processes for production of compounds from the synthesis gas generated during the coke gasification. The integrated process can also allow for reduced or minimized production of inorganic nitrogen compounds by using oxygen from an air separation unit as the oxygen source for gasification. Although the amount of nitrogen introduced as a diluent into the gasification will be reduced, minimized, or eliminated, the integrated process can also allow for gasification of coke while reducing, minimizing, or eliminating production of slag or other glass-like substances in the gasifier. Examples of compounds that can be produced from the synthesis gas include, but are not limited to, methanol, ammonia, and urea.

Abstract: A process for ammonia-urea production where: liquid ammonia produced in an ammonia section is fed to a urea section directly at the ammonia synthesis pressure, and where the liquid ammonia is purified at high pressure with the steps of: cooling the liquid ammonia (20) obtaining a cooled liquid ammonia stream (21), separating a gaseous fraction (22) comprising hydrogen and nitrogen from said cooled liquid ammonia, obtaining purified liquid ammonia (23) at a high pressure, and reheating said purified liquid ammonia (23) after separation of said gaseous fraction, obtaining a reheated purified ammonia (24) having a temperature suitable for feeding to the urea synthesis process. The application also deals with an ammonia-urea plant comprising an ammonia cooler, a liquid-gas separator and an ammonia re-heater and with a method for revamping existing ammonia-urea plants.

Abstract: The invention relates to a method of manufacturing urea as a nitrogen-rich synthetic fertilizer from refuse of any composition, preferably from domestic waste. The organic waste components are first turned into gas in a high-temperature reactor with oxygen (O2) which has been obtained in a cryogenic air separation plant. A synthesis gas arises which predominantly comprises carbon monoxide (CO), hydrogen (H2) and carbon dioxide (CO2). The carbon monoxide (CO) contained in the synthesis gas is subsequently converted with steam into hydrogen (H2) and carbon dioxide (CO2). The hydrogen is subsequently separated and is used for ammonia synthesis together with the elementary nitrogen (N2) which arises as a by-product in cryogenic air separation, In the last process step, urea (CO(NH2)2) is manufactured from ammonia (NH3) and the further synthesis gas component carbon dioxide (CO2).

Abstract: An integrated process for the manufacture of olefins and intermediates for the production of ammonia and urea, comprising an FCC reactor, a regenerator, a steam reforming unit, an air-separation unit, an ammonia production unit and a urea production unit, is described. This process makes it possible to minimize CO2 emissions to atmosphere, make use of heavy feedstocks of low added value (AR) for the production of light olefins, in addition to making maximum use of all the flows involved, thus increasing the energy efficiency achieved, all at the same time.

Abstract: A process for the direct synthesis of urea from ammonia and carbon dioxide at high pressures and temperatures, with the formation of ammonium carbamate as intermediate, comprising a decomposition step of the ammonium carbamate and stripping of the gases formed, operating substantially at the same pressure as the synthesis step, wherein the recycled liquid streams are fed, at least partially, to the same decomposition and stripping step after being preheated by heat exchange with a stream included in the high-pressure synthesis cycle.

Abstract: Disclosed is a process for the production of ammonia comprising a step wherein synthesis gas is formed in two different ways, viz. by catalytic partial oxidation (31) and by steam reforming, and wherein the combined streams of synthesis gas are subjected to a water gas shift reaction (50). Also disclosed is a process of producing urea, wherein ammonia is formed (90) in a process involving said combined streams and wherein carbon dioxide (110) formed in the same process is reacted with said ammonia so as to form urea.

Abstract: A process is provided for preparing C8-C22 acyl amido compounds via reaction in a polyol (molecular weight 76 to 400) of interesterifying a C1-C3 alkyl ester of a C8-C22 fatty acid with an amino compound or salt thereof. The resultant mass of material will have a Hunter Lab Color Scale value L ranging from 70 to 100.

Abstract: A process for ammonia -urea production where: liquid ammonia produced in an ammonia section is fed to a urea section directly at the ammonia synthesis pressure, and where the liquid ammonia is purified at high pressure with the steps of: cooling the liquid ammonia (20) obtaining a cooled liquid ammonia stream (21), separating a gaseous fraction (22) comprising hydrogen and nitrogen from said cooled liquid ammonia, obtaining purified liquid ammonia (23) at a high pressure, and reheating said purified liquid ammonia (23) after separation of said gaseous fraction, obtaining a reheated purified ammonia (24) having a temperature suitable for feeding to the urea synthesis process. The application also deals with an ammonia -urea plant comprising an ammonia cooler, a liquid-gas separator and an ammonia re-heater and with a method for revamping existing ammonia -urea plants.

Abstract: The present invention is directed to providing a method of producing synthetic fuels and organic chemicals from atmospheric carbon dioxide. Carbon dioxide gas is extracted from the atmosphere, hydrogen gas is obtained by splitting water, a mixture of the carbon dioxide gas and the hydrogen gas (synthesis gas) is generated, and the synthesis gas is converted into synthetic fuels and/or organic products. The present invention is also directed to utilizing a nuclear power reactor to provide power for the method of the present invention.

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: A method of producing urea includes reacting SiO2/Al2O3 or SiO2/Al2O3-containing material, with addition of a carbon source, with gaseous nitrogen at elevated temperature to produce silicon nitride (Si3N4)/aluminum nitride (AlN) or silicon nitride/aluminum nitride-containing material; reacting the silicon nitride/aluminum nitride or silicon nitride/aluminum nitride-containing material in the presence of a basic alkali metal compound and/or alkaline-earth metal compound, with water at elevated temperature, to produce ammonia and alkali metal silicates/aluminates and/or alkaline earth metal silicates/aluminates; and reacting the ammonia with carbon dioxide to produce the urea.

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: An integrated process for the manufacture of olefins and intermediates for the production of ammonia and urea, comprising an FCC reactor, a regenerator, a steam reforming unit, an air-separation unit, an ammonia production unit and a urea production unit, is described. This process makes it possible to minimize CO2 emissions to atmosphere, make use of heavy feedstocks of low added value (AR) for the production of light olefins, in addition to making maximum use of all the flows involved, thus increasing the energy efficiency achieved, all at the same time.

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: The present invention is directed to providing a method of producing synthetic fuels and organic chemicals from atmospheric carbon dioxide. Carbon dioxide gas is extracted from the atmosphere, hydrogen gas is obtained by splitting water, a mixture of the carbon dioxide gas and the hydrogen gas (synthesis gas) is generated, and the synthesis gas is converted into synthetic fuels and/or organic products. The present invention is also directed to utilizing a nuclear power reactor to provide power for the method of the present invention.

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: 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: 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: An ammonia and fertilizer production process is based on partial oxidation of fossil fuel, which co-produces polycarbonsuboxide. The four step process is low-cost and low-carbon-dioxide emission. It comprises the steps of reacting fossil fuel with oxygen in air and steam in an electric discharge plasma to produce a gas exit stream of polycarbonsuboxide, hydrogen with associated nitrogen (110); cooling the gas stream to condense and separate the polycarbonsuboxide as a solid polymer (120); compressing the gas stream to pressures for synthesis of ammonia (140); and, converting the gas stream to ammonia by employing a catalytic converter (150). Optional steps involve gas cleanup, which include removal of contaminants from the gas stream and adding hydrogen or nitrogen to the gas stream to adjust the ratio of hydrogen to nitrogen to three to one, respectively, prior to converting the gas stream to ammonia (130).

Abstract: A method of preparation of (R)-(?)-5-(2-aminopropyl)-2-methoxybenzenesulfonamide of formula I and its use for production tamsulosin. A protective group is introduced to N-[(1R)-2(4-methoxyphenyl)-1-methylethyl]-N-[(1R)-1-phenylethyl)]amine and the resulting amide of formula IX is chlorosulfonated and the resulting sulfochloride is converted to a sulfonamide of formula X, from which the compound of formula I is obtained by hydrogenation.

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: Ammonia is catalytically produced from a nitrogen-hydrogen mixture. First of all, a vaporous feed mixture, which comprises 30 to 60 vol-% methanol and 40 to 70 vol-% steam and has a volume ratio steam:methanol of 1 to 3, is passed through at least one bed of a breakdown catalyst at pressures in the range from 30 to 200 bar, the temperatures in the catalyst bed lying in the range from 200 to 500° C. From the catalyst bed, a first gas mixture is withdrawn, which, calculated dry, comprises 40 to 80 vol-% H2 and 10 to 30 vol-% CO2. The first gas mixture is cooled, CO2 is removed in a gas cleaning, and a second gas mixture is generated, which comprises at least 95 vol-% nitrogen and hydrogen, and which is supplied as synthesis gas to an ammonia synthesis for the catalytic production of ammonia.

Abstract: A method for producing ammonia from natural gas, fed to an autothermic reformer with an O2 rich gas. Crude synthesis gas is produced at temperatures of 900 to 1200° C., pressures of 40 to 100 bar and in the presence of a cracking catalyst. The crude synthesis gas is led through a catalytic conversion system to convert CO to H2, thereby obtaining a conversion synthesis gas with a H2 content of at least 55 vol.-% and a CO content of not more than 8 vol.-%. The conversion synthesis gas is subjected to a gas purification to remove CO2, CO and CH4, thereby producing an N2—H2 mixture that is subjected to a catalytic ammonia synthesis. The ammonia produced can at least be partially converted to urea by reacting it with CO2.

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 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 combined preparation of urea and ammonia reactant by steps of providing ammonia synthesis gas containing carbon dioxide and conversion of the synthesis gas to the ammonia reactant, reacting the ammonia reactant with the carbon dioxide in the synthesis gas to ammonium carbamate and to urea product, which process comprises further steps of prior to the conversion of the synthesis gas to the ammonia reactant, (i) washing the synthesis gas with an aqueous solution of the ammonia reactant and forming a solution being rich in ammonium carbamate; (ii) removing excess of ammonia reactant from the washed synthesis gas by washing with water and withdrawing an aqueous solution of ammonia reactant; (iii) purifying the water washed synthesis gas by removing remaining amounts of water and ammonia; and (iv) passing the purified synthesis gas to the conversion of the gas to ammonia reactant.

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: 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.

Abstract: A urea synthesis process with improved heat economy, wherein a urea synthesis solution obtained by removing most of the unreacted ammonium carbamate by stripping with carbon dioxide at a pressure approximately equal to a urea synthesis pressure is subjected to a high and low pressure decomposition. The gas mixture obtained from the high-pressure decomposition is condensed in at least two steps.

Abstract: The invention relates to a process for the preparation of urea from ammonia and carbon dioxide, the preparation being effected in whole or in part in a vertical combi-reactor. The gas stream leaving the stripper is fed to the condenser section of a vertical combi-reactor in which this gas stream is wholly or partially condensed in the carbamate stream which is transferred from the scrubber section to the condenser section via a downcomer. Ammonia and carbon dioxide are partially converted into urea in this condenser section of the combi-reactor. The urea conversion is completed in the reaction section of the combi-reactor.

Abstract: A plant for manufacturing urea from carbonaceous materials, oxygen from an air separation unit and water, preferably steam, is made up of a syngas generator unit, an air separation unit, Fischer-Tropsch unit, a CO2 removal unit, a hydrogen removal unit, a methanator unit, an ammonia converter unit and a urea synthesizer unit. Each of Fischer-Tropsch liquids, ammonia, hydrogen and urea can be recoverable under proper economic conditions. Electrical power is recoverable by the addition of at least one of a steam turbine and a gas turbine which is/are coupled to an electrical generator.

Abstract: Process for the combined preparation of urea and ammonia reactant by steps of providing ammonia synthesis gas containing carbon dioxide and conversion of the synthesis gas to the ammonia reactant, reacting the ammonia reactant with the carbon dioxide in the synthesis gas to ammonium carbamate and to urea product, which process comprises further steps of

Abstract: In the present process for the preparation of urea, an off-gas stream released during the synthesis of melamine in a high-pressure melamine process which consists predominantly of ammonia and carbon dioxide, is introduced into at least one high-pressure section of a urea stripping plant and is used in the synthesis of urea. The off-gas stream can be used directly without any further treatment.

Abstract: In a process for the production of urea, substantially pure ammonia and carbon dioxide are reacted in a reaction space (1) from which comes out a reaction mixture subjected to stripping (2) to obtain a partially purified mixture sent to a urea recovery section (3, 4, 7, 8). From the recovery section (3, 4, 7, 8) it is obtained a dilute carbamate solution, which is subjected to stripping (9) with recycling of vapors to the reaction space (1) after condensation (6). This process achieves high conversion yield with reduced energy consumption and low implementation costs.

Abstract: A method for the simultaneous modernization of a plant for ammonia synthesis and a plant for urea synthesis, provides—inter alia—the arrangement of a carbamate synthesis section and a carbamate decomposition section, in order to obtain a predetermined amount of carbamate in aqueous solution and of hydrogen and nitrogen in gaseous phase which are fed to the existing sections for urea synthesis, respectively ammonia synthesis. Thanks to this method of modernization it is possible to remarkably increase the production capacity and at the same time to reduce the energy consumption of the urea and ammonia plants without being forced to replace or anyway overload the existing sections of decarbonation, methanation and compression, in general.

Abstract: In a process for urea production, substantially pure ammonia and carbon dioxide are reacted in a main reaction space from which outgoes a reaction mixture subjected to stripping to obtain a partially purified mixture sent to a urea recovery section. From this section, a dilute carbamate solution is obtained which is recycled to an auxiliary reaction space in which the residual carbamate is converted into urea. This process achieves high average conversion yield with reduced energy consumption.

Abstract: Process for the revamping of urea production plants for the synthesis of ammonia (NH3) and carbon dioxide, with a stripping section with NH3, in which the process carries out with differentiated yields, a majority reaction a) between highly pure reagents and a reaction b) between less pure substantially recycled reagents, according to European Patent No. 91116297.2/0479103. According the invention, the urea solution is now fed upstream the stripping section and a reactor with heat removal is utilized. Advantageous, the production capacity of the existing reactor is reduced, with respect to the projected one, in a quantity of 35% to 5%, preferably from 20% to 10%, in favor of the capacity of the “once-through” reactor.

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: Method for increasing the capacity of an existing urea process, the existing urea process comprising a reactor (R), a pressure-reduction section (SC) and a urea-recovery section (U), characterized in that(i) a stripping column (S) is added, in which ammonium carbamate from the reaction mixture is stripped with carbon dioxide or is thermally stripped at almost the same elevated pressure, resulting in a gaseous mixture (G1) and a liquid mixture (M4), which liquid mixture (M4) is fed to the pressure-reduction section (SC),(ii) a condenser (C) is added, which is fed with the gaseous mixture (G1), ammonia and optionally carbon dioxide, in which the gaseous mixture (G1) is condensed at almost the same elevated reactor pressure (P) and at least 30% of the equilibrium amount of urea obtainable under the condensation conditions is furthermore formed, in which a liquid mixture containing urea, water and ammonium carbamate (MS) is formed, which mixture is fed to the bottom of the existing reactor (R), and a gaseous mixt

Abstract: In the present process for the preparation of urea, an off-gas stream released during the synthesis of melamine in a high-pressure melamine process which consists predominantly of ammonia and carbon dioxide, is introduced into at least one high-pressure section of a urea stripping plant and is used in the synthesis of urea. The off-gas stream can be used directly without any further treatment.

Abstract: The present invention provides an improved process for synthesizing urea from ammonia and carbon dioxide while preventing corrosion of sites, that are to be in contact with a condensate, of the joints of a tube plate and cooling tubes in a condenser installed vertically or horizontally. According to this process, the sites, that are to be in contact with the condensate, of the joints of the tube plate and the cooling tubes in the condenser are prevented from corrosion by enveloping the sites with liquid ammonia or a solution rich in ammonia in the synthesis of urea comprising separating unreacted ammonia and carbon dioxide as a gaseous mixture thereof from a urea synthesis solution at a pressure substantially equal to the urea synthesis pressure, bringing the gaseous mixture into contact with an absorption medium in the condenser to form a condensate, and recirculating the condensate to the synthesis column.

Abstract: Improved yield process for urea synthesis by starting from ammonia and carbon dioxide, comprising a reaction zone under high pressure and temperature conditions, a section wherein a portion of unreacted ammonia and carbon dioxide are stripped and recycled to the reactor, which section operates under substantially the same reactor pressure, and a subsequent section, operating under medium and/or low pressure conditions, for urea purification and simultaneous recovery of residual carbon dioxide and a portion of residual ammonia contained in the effluent stream from the stripping section, as an aqueous solution of ammonium carbamate, in which said aqueous ammonium carbamate solution is either totally or partially fed to said stripping section. Said process makes it possible a conversion of carbon dioxide into urea to be obtained in the reactor which is higher than 70%.

Abstract: A urea production process with high energy efficiency, in which the urea solution obtained from the synthesis stage is subjected to a first stage of high pressure thermal decomposition of the ammonium carbamate which has not undergone conversion to urea together with simultaneous self-stripping by excess ammonia, the gaseous products from said decomposition being condensed in two stages at different temperatures, in the first of which the heat is directly transferred to a second ammonium carbamate decomposition stage which is divided into two parts, namely a first thermal decomposition part and a second part consisting of adiabatic stripping with part of the carbon dioxide feed to the process.

Abstract: Urea is formed by the synthesis of ammonia with carbon dioxide at high pressure and temperature in an internal space of reactors through which flow a liquid phase cocurrently with a gas phase. The reactors are divided into compartments to avoid excessive mixing of the entire liquid phase and to allow the intermittent redistribution of the gas in bubbles of a suitable size for increasing the transfer of heat and mass between the two phases. At each passage from one compartment to the next, the liquid phase and the gas phase are made to flow on separate routes and are distributed in each compartment with a continuous, permanent, and even flow.

Abstract: An improved process for urea production as well as a method of retrofitting a pre-existing urea plant based on the Stamicarbon process are disclosed. According to the invention, a high-yield reactor with partial removal of the reaction heat and a urea recovery section of the solution leaving the high-yield reactor, are added to the pre-existing urea plant, means being provided for recycling unreacted ammonia and carbon dioxide vapors as well as a carbamate solution obtained in the urea recovery section to the pre-existing reactor.

Abstract: Improved yield process for urea synthesis by starting from ammonia and carbon dioxide, comprising a reaction zone under high pressure and temperature conditions, a section wherein a portion of unreacted ammonia and carbon dioxide are stripped and recycled to the reactor, which section operates under substantially the same reactor pressure, and a subsequent section, operating under medium and/or low pressure conditions, for urea purification and simultaneous recovery of residual carbon dioxide and a portion of residual ammonia contained in the effluent stream from the stripping section, as an aqueous solution of ammonium carbamate, in which said aqueous ammonium carbamate solution is either totally or partially fed to said stripping section. Said process makes it possible a conversion of carbon dioxide into urea to be obtained in the reactor which is higher than 70%.