Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/14—Fractional distillation or use of a fractionation or rectification column
  • B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
  • B01D3/148—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step in combination with at least one evaporator
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/14—Fractional distillation or use of a fractionation or rectification column
  • B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
  • B01D3/322—Reboiler specifications
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C273/00—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
  • C07C273/02—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups of urea, its salts, complexes or addition compounds
  • C07C273/04—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups of urea, its salts, complexes or addition compounds from carbon dioxide and ammonia
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/141—Feedstock
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Definitions

• the invention relates to methods and devices for producing urea from ammonia and carbon dioxide. State of the art
• SUBSTITUTE SHEET (RULE 26) the first stage, is used to remove part of the water from the urea solution, which leads to a decrease in the total cost of heating steam during the production of urea.
• a plant for producing urea including a urea synthesis reactor, a device with heat from an external source for distilling the urea melt obtained in the synthesis reactor at the first pressure stage, a device with heat from an external source for distilling a urea melt the second stage of pressure, apparatus for evaporation during heating of the aqueous urea solution obtained in the second stage of distillation, apparatus for condensation-absorption during cooling of ha distillation of both stages, a heat exchanger-recuperator for heat exchange between the distillation gases of the first stage and an aqueous urea solution, means for feeding ammonia and carbon dioxide to the urea synthesis reactor, urea melt from the synthesis reactor to the first stage distillation device and from the first stage distillation device to the apparatus for distillation of the second stage, an aqueous urea solution from the apparatus for distillation of the second stage to the heat exchanger-recuperator and from the heat exchanger-recuperator to the apparatus for following
• SUBSTITUTE SHEET (RULE 26) stages distillation gases from the second stage distillation apparatus to the second stage condensation-absorption apparatus, ammonium carbamate solution from the second stage condensation-absorption apparatus to the first stage condensation-absorption apparatus and from the first stage condensation-absorption apparatus to synthesis reactor (US 3366682, 260-555, 1968).
• synthesis reactor US 3366682, 260-555, 1968.
• the technical result to which the invention is directed is to further increase the degree of heat recovery of the production cycle and reduce the number of heat exchangers using heating steam from external sources.
• a method for producing urea by the interaction of ammonia and carbon dioxide in the synthesis zone at elevated temperatures and pressures with the formation of a urea melt stream containing urea, water, ammonium carbamate, ammonia and carbon dioxide, distillation of a urea melt stream with heat at two stages is proposed.
• a plant for producing urea including a urea synthesis reactor, a device with heat supply from an external source for distillation of urea melt obtained in
• SUBSTITUTE SHEET (RULE 26) synthesis reactor at the first pressure stage, a device with heat supply for distillation of urea melt at the second pressure stage, apparatus for evaporating upon heating an aqueous urea solution obtained at the second distillation stage, condensation-absorption devices for cooling distillation gases of both stages, heat exchanger-recuperator for heat exchange between the distillation gases of the first stage and an aqueous urea solution, means for feeding ammonia and carbon dioxide to the urea synthesis reactor, urea melt from p synthesis reactor to the device for distillation of the first stage and from the device for distillation of the first stage to the device for distillation of the second stage, an aqueous solution of urea from the device for distillation of the second stage to the heat exchanger-recuperator and from the heat exchanger-recuperator to the apparatus for subsequent evaporation of distillation gases from a device for distillation of the first stage to a heat exchanger-recuperator and from a heat exchange
• gases from the first zone of the first distillation stage are sent to the condensation-absorption stage of the first stage distillation gases after heat exchange in series with the urea melt in the second distillation stage and with an aqueous urea solution at the preliminary evaporation stage, and gases from the second zone of the first the distillation stages are returned to the first zone of the first distillation stage and / or attached to the gases from the first zone of the first distillation stage before their heat exchange with the urea melt for the second second Upenu its distillation.
• the installation in this case as means for supplying distillation gases from the first stage distillation device to the heat exchanger-recuperator, contains means for supplying distillation gases from the first stage distillation column to the heating zone of the second stage distillation device, means for supplying distillation gases from a film heat exchanger to the first stage distillation column and / or to the heating zone of the second stage distillation device and means for supplying distillation gases from the heating zone of the distillation device second stage in a heat exchanger-recuperator.
• the gases from the first zone of the first distillation stage are sent directly to the condensation-absorption stage of the first stage distillation gases, and the gases from the second zone of the first distillation stage are directed to the condensation-absorption stage of the first distillation gases after their heat exchange in series with the carbamide melt to the second stages of its distillation and with an aqueous solution of urea at the stage of preliminary evaporation.
• the installation in this case as means for supplying distillation gases from the first stage distillation device to the heat exchanger-recuperator, comprises means for supplying distillation gases from the film heat exchanger to the heating zone of the second stage distillation device and from the heating zone of the second stage distillation device to the heat exchanger-recuperator and further comprises means for supplying distillation gases from the first stage distillation column directly to the condensation-absorption device
• gases from the first zone of the first distillation stage are sent directly to the condensation-absorption stage of the first stage distillation gases, and gases from the second zone of the first distillation stage are sent to the condensation-absorption stage of the first stage distillation gases after heat exchange with an aqueous urea solution in the stage pre-evaporation.
• the installation in this case contains means for supplying distillation gases from the film heat exchanger to the heat exchanger-recuperator and further comprises means for supplying distillation gases from the first distillation column stage directly into the device for condensation-absorption of distillation gases of the first stage.
• the supply of heat to the heating zone of the device for distillation of the second stage in this case is carried out from an external source.
• FIG. 1-3 depict plant diagrams, which are specific embodiments of the invention and implementing the above modifications of the proposed method.
• urea production plant includes a urea synthesis reactor 1, a urea melt distillation device obtained in a reactor 1, consisting of a first stage 2 distillation column and a film heat exchanger 3 connected in series with it, a urea melt distillation unit at a second pressure stage, consisting of distillation columns of the second stage 4, recuperative heat exchanger 5 and separator 6, apparatus for pre-evaporation of an aqueous urea solution, consisting of a separator 7 and a heat exchanger - recuperator 8, a device 9 for condensation-absorption during cooling of the second stage distillation gases, which is a shell-and-tube heat exchanger, a device for condensation-absorption during cooling of the first stage distillation gases, consisting of a washing column 10, a remote heat exchanger 11, a return ammonia condenser 12 and a washing scrubber 13, ammonia feed pump 14 and compressor 15 for feeding carbon dioxide into reactor 1, feed line 16
• SUBSTITUTE SHEET (RULE 26) urea melt from the reactor 1 to the distillation column 2, a pipe 17 for supplying carbon dioxide to the film heat exchanger 3, a pipe 18 for supplying urea melt from the film heat exchanger 3 to the second stage distillation column 4, a pipe 19 for supplying an aqueous urea solution from the separation a torus 6 to a separator 7, a pipe 20 for supplying an aqueous urea solution from a heat exchanger-recuperator 8 to apparatuses for further evaporation (not shown in Fig.
• a pipe 21 for supplying distillation gases from the column 2 to the annulus the regenerative heat exchanger 5 pipe 22 for supplying distillation gases from the regenerative heat exchanger 5 to the annular space of the heat exchanger-recuperator 8, pipeline 23 for supplying distillation gases from the heat exchanger-recuperator 8 to the external heat exchanger 11, pipe 24 for supplying distillation gases from the 4 distillation column a device 9 for condensation-absorption of distillation gases of the second stage, a pump 25 for supplying a solution of ammonium carbamate from a device 9 for condensation-absorption of distillation gases of a second stage neither to the external heat exchanger I, pump 26 for supplying a solution of ammonium carbamate from the wash column 10 to the synthesis reactor 1, pipe 27 for supplying ammonia return from the condenser 12 to pump 14, pipe 28 for discharging inert gases purified from ammonia into the atmosphere, pipe 29 for feeding inert gases with an admixture of ammonia into the tail absorber (
• FIG. 2 differs from the installation shown in FIG. 1, only in that the pipe 21 is designed to supply distillation gases from the column 2 directly to the external heat exchanger 11, the pipe 31 is for supplying distillation gases from the film heat exchanger 3 to the annular space of the recuperative heat exchanger 5, and the pipe 32 is absent.
• the apparatus shown in FIG. 3 differs from the installation shown in FIG. 2, only in that the pipe 31 is designed to supply distillation gases from the film heat exchanger 3 directly to the annular
• EXAMPLE 1 In accordance with FIG. 1, synthesis ammonia column 1 is supplied with liquid ammonia supplied by pump 14, carbon dioxide supplied by compressor 15, and ammonium carbamate return solution supplied by pump 26. Column 1 is supplied with a pressure of 180-200 kgf / cm 2 and a temperature of 180-195 ° C the synthesis of urea with the formation of a melt (gas-liquid mixture) containing urea, water, ammonium carbamate, not converted to urea, and excess ammonia.
• a melt gas-liquid mixture
• the melt is throttled to a pressure of 15-25 kgf / cm and through a pipe 16 enters with a temperature of 125 ° C into the distillation column of the first stage 2, equipped with mass and heat exchange devices, where, with or without heat, part of the ammonium carbamate decomposes and is released from the melt ammonia and carbon dioxide.
• the melt from the column 2 enters the film heat exchanger 3, heated by steam, where the distillation process is completed at the same pressure and 150-165 ° C.
• a portion of carbon dioxide from compressor 15 enters the film heat exchanger 3 through pipeline 17.
• Gases from the film heat exchanger 3 with a temperature of 148-15O 0 C enter through line 32 to column 2, where they are again contacted with the urea melt, heating it to 138-14O 0 C , either partially or completely, through pipeline 31 to pipeline 21.
• the melt from the film heat exchanger 3 is throttled to a pressure of 1.5-5 kgf / cm 2 and through pipeline 18 enters the second distillation column — stage 4 A, where, at the specified pressure continues to decompose ammonium carbamate and evolution of ammonia and carbon dioxide from the melt, ending in a recuperative heat exchanger 5 and a separator 6.
• the recuperative heat exchanger 5 is heated by the first stage distillation gases entering its annulus from the column 2 and the film heat exchanger 3 (directly or through column 2) through the pipe 21
• the urea solution from the separator 6, practically freed from ammonium carbamate, is throttled to atmospheric pressure and through a pipe 19 enters the separator 7 and then into the heat exchanger-recuperator pipes ra 8, wherein in the film mode,
• SUBSTITUTE SHEET (RULE 26) partial evaporation of water from the solution occurs due to heat exchange with distillation gases entering the annular space of the heat exchanger-recuperator 8 from the annular space of the recuperative heat exchanger 5 through the pipe 22.
• a urea solution with a concentration of ⁇ 78% from the heat exchanger-recuperator 8 is sent for further evaporation and granulation by known methods through pipeline 20.
• the second stage distillation gases from column 4 are condensed in apparatus 9 to form a dilute solution of ammonium carbamate.
• the distillation gases of the first stage with an admixture of liquid condensation products from the annular space of the heat exchanger-recuperator 8 are supplied with a temperature of 110-115 ° C to the external heat exchanger 11 of the washing column 10.
• condensation is absorbed, the absorption of distillation gases upon their contact with water, liquid ammonia and a solution of ammonium carbamate obtained by condensation-absorption of the second stage distillation gases in the apparatus 9.
• the purified ammonia gas removed from the upper part of the wash column condenses when water in the condenser 12 and returns through the pipe 27 to the suction line of the pump 14.
• the non-condensed gases are washed from the ammonia residues with water in the scrubber 13 and are discharged into the atmosphere via the pipe 28.
• a concentrated solution of ammonium carbamate formed in the lower part of the wash column 10 and the external heat exchanger 11 returns to synthesis reactor 1 by pump 26.
• Vapors from separator 7 and heat exchanger 9 are fed through line 29 to a sanitary absorber (in FIG. 1 not shown).
• Vapors from the heat exchanger-recuperator 8 through the pipeline 30 enter the unit of condensation of the vapor of the evaporation stage (not shown in Fig. 1).
• EXAMPLE 2 The process is carried out on the installation, a diagram of which is shown in FIG. 2, basically, similar to example 1.
• SUBSTITUTE SHEET (RULE 26) EXAMPLE 3 The process is carried out on the installation, a diagram of which is shown in FIG. 3, basically, similar to example 2. The difference is that the gases from the film heat exchanger 3 with a temperature of 148-150 ° C enter through the pipe 31 into the annular space of the heat exchanger-recuperator 8, bypassing the annular space of the heat exchanger 5, and from there - in the remote heat exchanger 11 of the washing column 10, which also receives gases from the column 2 through the pipe 21.
• the heat exchanger 5 is heated by steam from an external source.
• the urea solution with a concentration of -80% from the heat exchanger-recuperator 8 is sent for further evaporation and granulation by known methods through the pipeline 20.
• the invention can be used to obtain urea from ammonia and carbon dioxide.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2005
  • 2005-04-18 RU RU2005111522/04A patent/RU2280026C1/ru active
• 2006
  • 2006-03-20 UA UAA200707632A patent/UA85467C2/ru unknown
  • 2006-03-20 WO PCT/RU2006/000128 patent/WO2006112751A1/ru active Application Filing
  • 2006-03-20 EE EEP200700056A patent/EE05451B1/et not_active IP Right Cessation
• 2007
  • 2007-07-19 LT LT2007043A patent/LT5476B/lt not_active IP Right Cessation

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