Preparing Directly From Ammonium Carbamate (i.e., From Hnh-coo-hhnhh) Patents (Class 564/66)
  • Patent number: 9988345
    Abstract: The present invention regards a process for the production of an aqueous solution comprising urea for use in the removal of nitrogen oxides from combustion gas or fumes, the process being characterized in that it comprises the steps of: —subjecting at least a part of a urea-concentrated aqueous solution comprising residual free ammonia, obtained directly from or downstream of a recovery section of a plant for the production of urea, to washing with carbon dioxide, so obtaining a first vapor phase comprising carbon dioxide and optionally ammonia and a urea-concentrated aqueous solution comprising carbamate and essentially lacking in free ammonia, and —diluting said urea-concentrated aqueous solution comprising carbamate and essentially lacking in free ammonia with water until the desired concentration of urea in aqueous solution is reached.
    Type: Grant
    Filed: January 30, 2008
    Date of Patent: June 5, 2018
    Assignee: Casale SA
    Inventor: Federico Zardi
  • Patent number: 9770699
    Abstract: A method for revamping a self-stripping urea plant comprising the installation of a new CO2-stripping synthesis section (6), wherein at least part of the aqueous urea solution (10) leaving said new section (6) is directed to the existing low pressure recovery section (4) of the self-stripping plant, by-passing the existing self-stripping high-pressure section (2) and medium pressure treatment section (3).
    Type: Grant
    Filed: March 5, 2014
    Date of Patent: September 26, 2017
    Assignee: Casale SA
    Inventors: Andrea Scotto, Paolo Bertini, Serena Gabbiadini
  • Patent number: 8927770
    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.
    Type: Grant
    Filed: May 3, 2012
    Date of Patent: January 6, 2015
    Assignee: Salpem, S.p.A.
    Inventors: Lino Carlessi, Alessandro Gianazza
  • Patent number: 8481786
    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.
    Type: Grant
    Filed: November 30, 2009
    Date of Patent: July 9, 2013
    Assignee: Kellogg Brown & Root LLC
    Inventor: Vishnu D. Singh
  • Patent number: 8383856
    Abstract: A process for urea production from ammonia and carbon dioxide, made to react at a predetermined high pressure in an appropriate synthesis reactor (112), from the reaction between NH3 and CO2 being obtained a reaction mixture comprising urea, ammonium carbamate and free ammonia in aqueous solution, from which a recovery of ammonium carbamate and ammonia is carried out with their subsequent recycle to the synthesis reactor (112), said recovery from the reaction mixture taking place through operative steps of decomposition of the ammonium carbamate into NH3 and CO2 and of their stripping and a subsequent operative step of their recondensation into ammonium carbamate that is recycled to the synthesis reactor, the said reaction mixture obtained from the reaction between ammonia and carbon dioxide being pumped to the operative steps of decomposition and stripping.
    Type: Grant
    Filed: November 15, 2005
    Date of Patent: February 26, 2013
    Assignee: Urea Casale S.A.
    Inventors: Domenico Romiti, Paolo Sticchi
  • Patent number: 8377399
    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.
    Type: Grant
    Filed: March 30, 2009
    Date of Patent: February 19, 2013
    Assignee: Stamicarbon B.V.
    Inventor: Johannes Henricus Mennen
  • Patent number: 7732640
    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.
    Type: Grant
    Filed: July 22, 2005
    Date of Patent: June 8, 2010
    Assignee: Urea Casale S.A.
    Inventors: Domenico Romiti, Paolo Sticchi
  • Publication number: 20100076222
    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.
    Type: Application
    Filed: November 30, 2009
    Publication date: March 25, 2010
    Applicant: KELLOGG BROWN & ROOT LLC
    Inventor: Vishnu D. Singh
  • Patent number: 7674933
    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.
    Type: Grant
    Filed: March 19, 2008
    Date of Patent: March 9, 2010
    Assignee: Urea Casale S.A.
    Inventor: Federico Zardi
  • Publication number: 20100016635
    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.
    Type: Application
    Filed: July 21, 2008
    Publication date: January 21, 2010
    Applicant: KELLOGG BROWN & ROOT LLC
    Inventor: Vishnu D. Singh
  • Patent number: 7642377
    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.
    Type: Grant
    Filed: July 21, 2008
    Date of Patent: January 5, 2010
    Assignee: Kellogg Brown & Root LLC
    Inventor: Vishnu D. Singh
  • Patent number: 7619114
    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.
    Type: Grant
    Filed: November 12, 2007
    Date of Patent: November 17, 2009
    Assignee: Urea Casale S.A.
    Inventor: Giorgio Pagani
  • Publication number: 20090216045
    Abstract: Apparatus and methods for producing urea are provided. In one or more embodiments, an apparatus for producing urea can include a first zone, which can include a first flow channel in fluid communication with a first tube disposed about a first end of a plurality of trays, a second flow channel in fluid communication with a second tube disposed about the first end of the trays and a second end of the trays, and a third flow channel in fluid communication with a third tube disposed about the first and second ends of the trays. The apparatus can include a second zone, which can include a fixed bed comprising one or more inert packing materials disposed therein to provide additional surface area. The apparatus can include a third zone, which can include a plurality of tubes disposed therein. The second zone can be disposed between the first and third zones.
    Type: Application
    Filed: February 27, 2008
    Publication date: August 27, 2009
    Inventor: VISHNU D. SINGH
  • Patent number: 7279599
    Abstract: Method for carbamate condensation of a carbon dioxide/ammonia gaseous phase in a liquid phase in a condensation unit of the so-called submerged type comprising a heat exchange tube bundle having a predetermined number of tubes intended for carbamate condensation, wherein the gaseous phase and the liquid phase are fed contemporaneously and independently to each of the tubes intended for condensation.
    Type: Grant
    Filed: September 10, 2004
    Date of Patent: October 9, 2007
    Assignee: Urea Casale S.A.
    Inventor: Lorenzo Pennino
  • Patent number: 7220882
    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.
    Type: Grant
    Filed: April 17, 2006
    Date of Patent: May 22, 2007
    Assignee: Urea Casale S.A.
    Inventors: Lino Porro, Pasquale Gueli
  • Patent number: 7094927
    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.
    Type: Grant
    Filed: July 10, 2003
    Date of Patent: August 22, 2006
    Assignee: DSM IP Assets B.V.
    Inventors: Tjay Tjien Tjioe, Jozef Hubert Meessen
  • Patent number: 6855846
    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.
    Type: Grant
    Filed: November 1, 2001
    Date of Patent: February 15, 2005
    Assignee: DSM IP Assets B.V.
    Inventors: Andreas Johannes Biermans, Kees Jonckers
  • Publication number: 20040199013
    Abstract: The invention relates to a method for obtaining an ammonium carbamate solution from a gas mixture that contains more than 40 wt. % NH3, less than 50 wt. % CO2 and less than 40 wt. % H2O and has a pressure between 0.1 MPa and 4 MPa, comprising a compression step, in which the pressure of the gas mixture is increased to a pressure between 0.5 MPa and 25 MPa, and an absorption step.
    Type: Application
    Filed: January 13, 2004
    Publication date: October 7, 2004
    Inventor: Guillame Mario Hubert Jozef Lardinois
  • Patent number: 6730811
    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.
    Type: Grant
    Filed: June 2, 2000
    Date of Patent: May 4, 2004
    Assignee: DSM N.V.
    Inventor: Johannes H. Mennen
  • Patent number: 6696026
    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.
    Type: Grant
    Filed: January 16, 2001
    Date of Patent: February 24, 2004
    Assignee: Urea Casale
    Inventors: Giorgio Pagani, Umberto Zardi
  • Publication number: 20040028578
    Abstract: A carbamate condensation unit of the submerged type for synthesis urea production plants comprising a tube bundle for the condensation of gaseous compounds, is distinguished in that it further comprises a duct, structurally independent from the tube bundle, for the circulation of part of the condensed gaseous compounds inside the condensation unit.
    Type: Application
    Filed: August 25, 2003
    Publication date: February 12, 2004
    Inventor: Federico Zardi
  • Patent number: 6680407
    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.
    Type: Grant
    Filed: September 26, 2002
    Date of Patent: January 20, 2004
    Assignee: DSM N.V.
    Inventor: Johannes Henricus Mennen
  • Patent number: 6649795
    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.
    Type: Grant
    Filed: February 15, 2002
    Date of Patent: November 18, 2003
    Assignee: Urea Casale S.A.
    Inventors: Giorgio Pagani, Federico Zardi, Domenico Romiti
  • Patent number: 6538157
    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.
    Type: Grant
    Filed: June 12, 2002
    Date of Patent: March 25, 2003
    Assignee: Continental Engineering B.V.
    Inventors: Josephus Johannes Petrus Maria Goorden, Jacobus Johannes De Wit
  • Publication number: 20030013914
    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.
    Type: Application
    Filed: February 15, 2002
    Publication date: January 16, 2003
    Inventors: Giorgio Pagani, Federico Zardi, Domenico Romiti
  • Patent number: 6344588
    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.
    Type: Grant
    Filed: June 30, 2000
    Date of Patent: February 5, 2002
    Assignee: DSM, N.V.
    Inventor: Julius G. T. Van Wijck
  • Patent number: 6287525
    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.
    Type: Grant
    Filed: August 25, 1997
    Date of Patent: September 11, 2001
    Assignee: Urea Casale
    Inventor: Giorgio Pagani
  • Publication number: 20010002245
    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.
    Type: Application
    Filed: January 16, 2001
    Publication date: May 31, 2001
    Inventors: Giorgio Pagani, Umberto Zardi
  • Patent number: 6118023
    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
    Type: Grant
    Filed: January 9, 1998
    Date of Patent: September 12, 2000
    Assignee: DSM N.V.
    Inventors: Kees Jonckers, Hendrik F. Perree
  • Patent number: 6114579
    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.
    Type: Grant
    Filed: August 29, 1997
    Date of Patent: September 5, 2000
    Assignee: DSM. N.V.
    Inventor: Julius G. T. Van Wijck
  • Patent number: 5767313
    Abstract: The present invention relates to a process and apparatus for the preparation of urea, and in particular for urea obtained from ammonium carbamate formulated from carbon dioxide and ammonia at a pressure of about 125 bar to about 350 bar in a urea synthesis solution in a urea reactor. The reactor defines a horizontally arranged condensation zone and contains a heat exchanger. According to this process, NH.sub.3 and CO.sub.2 are supplied to the reactor and are largely absorbed into the urea synthesis solution. A substantial portion of the heat formed in the condensation is discharged by means of the heat exchanger. The residence time of the urea synthesis solution in the reactor preferably is selected so that at least about 85% of the theoretically obtainable amount of urea is prepared. Thereafter, the urea synthesis solution can be processed into a urea solution or solid urea.
    Type: Grant
    Filed: May 23, 1996
    Date of Patent: June 16, 1998
    Assignee: DSM N.V.
    Inventor: Kees Jonckers
  • Patent number: 5750780
    Abstract: A process for the synthesis of urea starting from ammonia and carbon dioxide, comprising a reaction step carried out in at least two distinct operating zones basically at the same pressure, but having a different operating temperature, the difference being preferably between 5.degree. and 60.degree. C., and subsequent separation steps of the non-converted reagents, wherein a gaseous stream is transferred from the first zone, at a higher temperature, to the second zone, at a lower temperature, and a liquid stream, containing urea and/or ammonium carbamate, is transferred from the second zone to the first, so that said gaseous stream is preferably at least 5% by weight with respect to the stream effluent from the first zone to the subsequent separation steps. This process allows a ratio urea/(urea+carbamate), in the stream leaving said reaction step, of more than 70%, to be obtained.
    Type: Grant
    Filed: December 22, 1995
    Date of Patent: May 12, 1998
    Assignee: Snamprogetti S.p.A.
    Inventor: Carlo Rescalli
  • Patent number: 5597454
    Abstract: A urea production process combining lower pressure urea concentration and carbamate recovery steps into a single non-vacuum operation. Following high pressure stripping wherein a bulk of unreacted carbamate is recovered from the reaction effluent, remaining carbamate is stripped by heated air at atmospheric pressure wherein urea is concurrently concentrated without the use of vacuum evaporators. Weak carbamate solution subsequently formed is stripped of water (and residual urea is hydrolyzed) using air and steam at a medium pressure single tower hydrolyzer/stripper to obtain a concentrated carbamate stream suitable for recycle to the reactor. The process employs heat integration for enhanced energy efficiency and produces a good quality aqueous condensate suitable for direct use as boiler feed water. Thus the aqueous condensate produced requires no additional cooling and ammonia treatment. The process employs simplified and reduced process unit operation to eliminate equipment for cost reduction.
    Type: Grant
    Filed: April 6, 1995
    Date of Patent: January 28, 1997
    Inventor: Jing M. Lee
  • Patent number: 5523482
    Abstract: In a process of producing urea in which ammonia and carbon dioxide are reacted in a first reaction space (E-1, R-1) the unreacted carbamate present in the reaction mixture is subjected to a thermal decomposition treatment, so as to obtain ammonia and carbon dioxide which are sent to a second reaction space (R-2) in which they react with a solution of recycled carbamate coming from an urea recovery section (3). Advantageously, the regulation of the temperature and of the ammonia/carbon dioxide molar ratio in the second reaction space (R-2) is carried out by respectively regulating the temperature of the recycled carbamate solution and the temperature of the thermal decomposition treatment of the residual carbamate leaving the first reaction space (E-1, R-1).
    Type: Grant
    Filed: May 2, 1994
    Date of Patent: June 4, 1996
    Assignee: Urea Casale S.A.
    Inventor: Giorgio Pagani
  • Patent number: 5403956
    Abstract: A process is described for the industrial synthesis of urea, making the ammonia (NH3) and the carbon dioxide (CO2) react, in at least one reaction space, at high pressures and temperatures and recycling at least in part the unreacted products obtained in a recycle section, characterized by: a) a synthesis reaction between reactants of high purity; and b) a synthesis reaction between less pure reactants, substantially recycled by the so-called recycle section.The corresponding new plant includes a reactor (R1) of high yield ("once through"), a reactor (R2) of lower yield and a section of recovery and recycle.The application of the process to preexisting plants requires the simple addition of a reactor of high yield and of pumping devices.
    Type: Grant
    Filed: April 2, 1993
    Date of Patent: April 4, 1995
    Assignee: Urea Casale, S.A.
    Inventor: Giorgio Pagani
  • Patent number: 5359140
    Abstract: A urea production process in which the urea solution produced in the reaction zone is treated in sequence with a first thermal decomposer at the same pressure as the reaction, to decompose part of the residual ammonium carbamate into its components, then with an adiabatic stripper in which the free ammonia is stripped with CO.sub.2 operating at a pressure which is 1-7 MPa less than the synthesis pressure, then with two further carbamate thermal decomposition stages at decreasing pressures. The gaseous products obtained from those stages at pressures less than the synthesis pressure are mixed with the recycle solutions from the downstream stages, condensed by heat transfer against said downstream stages, and then recycled to the reaction as liquid.
    Type: Grant
    Filed: March 19, 1992
    Date of Patent: October 25, 1994
    Assignee: Snamprogetti S.p.A.
    Inventors: Franco Granelli, Giuseppe Carloni
  • Patent number: 5316554
    Abstract: Ammonium carbamate, in solution with urea, water and ammonia and under high temperature and pressure is cooled to below its crystallization temperature while being subjected to an elevated pressure. The crystallized substance formed is then dried, crushed, and pelletized with the aid of a binding agent to produce pellets having substantial strength and stability, and having particular utility as a deicer for roadways.
    Type: Grant
    Filed: July 28, 1993
    Date of Patent: May 31, 1994
    Inventor: Charles N. Hansen
  • Patent number: 4988491
    Abstract: The process of the present invention which produces the flexible integration for the production of ammonia and urea uses adiabatic reforming of the carbonaceous feedstock such as natural gas. With adiabatic reforming of natural gas, a surplus of carbon dioxide is produced. With adiabatic reforming, substantially pure oxygen and nitrogen may be used which does not involve inert gases such as argon in the system. More importantly, adibatic reforming allows operation at much higher pressure than standard primary reforming, namely, between 700 and 3000 psig. When these pressures are used, the process includes a recycle of the methane and hydrogen from the ammonia synthesis loop to the adiabatic reformer.The process of the present invention uniquely removes the carbon dioxide which is produced by the reforming of the carbonaceous feedstock and treatment by the watergas shift reaction in two independent stages.
    Type: Grant
    Filed: April 11, 1989
    Date of Patent: January 29, 1991
    Inventors: Christiaan Van Dijk, Lowell D. Fraley
  • Patent number: 4613697
    Abstract: A process for the displacement to the gaseous phase, at 80-250 Kg/cm.sup.2, of the excess NH.sub.3 contained in an aqueous urea solution, coming, at 150.degree.-230.degree. C., from a former stripping, isobaric with the urea synthesis, and containing also CO.sub.2 as ammonium carbamate. The CO.sub.2 is, at most, 25% b.w. of the urea, and the displacement is performed by means of a CO.sub.2 stripping within a falling-film exchanger, hereinafter called the CO.sub.2 stripper, isobaric too with said synthesis. The amount of carbamate leaving the bottom of said CO.sub.2 stripper is substantially equal to the amount of carbamate entering the same stripper. The global NH.sub.3 :CO.sub.2 ratio, in the solution entering the CO.sub.2 stripper, is from 2 to 8 b.w. and heat is supplied only to the uppermost portion of the pipes of the CO.sub.
    Type: Grant
    Filed: December 26, 1984
    Date of Patent: September 23, 1986
    Assignee: Montedison S.p.A.
    Inventor: Giorgio Pagani
  • Patent number: 4382800
    Abstract: Soluble polymeric colorants composed of free amine groups and chromophoric groups covalently bonded to an organic backbone are disclosed. The number of free amine groups is not less than one-half the number of chromophoric groups. The colorants are characterized by being free of sulfonate, phosphonate and carboxylate groups. The preparation and use of these colorants is also disclosed.
    Type: Grant
    Filed: September 28, 1981
    Date of Patent: May 10, 1983
    Assignee: Dynapol
    Inventors: Patricia C. Wang, Robert E. Wingard, Jr.
  • Patent number: 4320103
    Abstract: In an integrated flexible installation for producing ammonia and urea, the improved method which consists in that a portion of the gaseous stream comprising carbon dioxide, hydrogen and nitrogen is fed to a complementary decarbonation area and then admixed with a portion of a similar, but non-decarbonated stream of gas prior to entering the carbon-dioxide-absorption unit. Liquid ammonia is recovered from a portion of the ammoniated aqueous solution used for abating the ammonia and sent to a distillation column to recover liquid ammonia therefrom.
    Type: Grant
    Filed: September 4, 1980
    Date of Patent: March 16, 1982
    Assignee: Snamprogetti S.p.A.
    Inventor: Giorgio Pagani
  • Patent number: 4291006
    Abstract: In an integrated or combined process for the production of ammonia and urea, the improvement consisting in that the absorption of CO.sub.2 from the raw gas going to the synthesis reactor for ammonia is carried out with an absorption apparatus which is divided into two sections, one being of the plate type and the other of the thin film type. The predominant fraction of CO.sub.2 is stripped in the thin-film section, the remainder in the adiabatic plate section.
    Type: Grant
    Filed: July 20, 1979
    Date of Patent: September 22, 1981
    Assignee: Snamprogetti S.p.A
    Inventors: Giorgio Pagani, Vincenzo Lagana, Francesco Saviano