AU2002360227B2 - Process for the preparation of urea - Google Patents
Process for the preparation of urea Download PDFInfo
- Publication number
- AU2002360227B2 AU2002360227B2 AU2002360227A AU2002360227A AU2002360227B2 AU 2002360227 B2 AU2002360227 B2 AU 2002360227B2 AU 2002360227 A AU2002360227 A AU 2002360227A AU 2002360227 A AU2002360227 A AU 2002360227A AU 2002360227 B2 AU2002360227 B2 AU 2002360227B2
- Authority
- AU
- Australia
- Prior art keywords
- pressure
- urea
- steam
- condenser
- process according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
- 239000004202 carbamide Substances 0.000 title claims description 51
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims description 50
- 238000000034 method Methods 0.000 title claims description 30
- 238000002360 preparation method Methods 0.000 title claims description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 27
- 230000015572 biosynthetic process Effects 0.000 claims description 24
- 238000003786 synthesis reaction Methods 0.000 claims description 21
- 238000000354 decomposition reaction Methods 0.000 claims description 19
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 16
- KXDHJXZQYSOELW-UHFFFAOYSA-N carbonic acid monoamide Natural products NC(O)=O KXDHJXZQYSOELW-UHFFFAOYSA-N 0.000 claims description 15
- 229910021529 ammonia Inorganic materials 0.000 claims description 14
- BVCZEBOGSOYJJT-UHFFFAOYSA-N ammonium carbamate Chemical group [NH4+].NC([O-])=O BVCZEBOGSOYJJT-UHFFFAOYSA-N 0.000 claims description 14
- 238000009833 condensation Methods 0.000 claims description 12
- 230000005494 condensation Effects 0.000 claims description 12
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 8
- 239000001569 carbon dioxide Substances 0.000 claims description 7
- 241000940835 Pales Species 0.000 claims 1
- 206010033546 Pallor Diseases 0.000 claims 1
- 239000007789 gas Substances 0.000 description 9
- KXDHJXZQYSOELW-UHFFFAOYSA-M Carbamate Chemical compound NC([O-])=O KXDHJXZQYSOELW-UHFFFAOYSA-M 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000002904 solvent Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000002826 coolant Substances 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011552 falling film Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- 150000003672 ureas Chemical class 0.000 description 1
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0006—Controlling or regulating processes
- B01J19/0013—Controlling the temperature of the process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00121—Controlling the temperature by direct heating or cooling
- B01J2219/0013—Controlling the temperature by direct heating or cooling by condensation of reactants
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
1 PROCESS FOR THE PREPARATION OF UREA The invention relates to a process for the preparation of urea from carbon Sdioxide and ammonia in a urea synthesis reactor by means of a urea stripping 0 5 process.
An embodiment of the invention is a process for the preparation of urea from c carbon dioxide and ammonia by means of a urea stripping process comprising a highpressure condenser and a high-pressure stripper, whereby a urea synthesis solution q is formed and wherein the steam condensate that forms during high-pressure stripping of the urea synthesis solution is utilized for medium-pressure decomposition C of the ammonium carbamate in the urea synthesis solution, wherein a combination of the steam condensate and steam A, which forms in the high-pressure condenser, or only steam A is used for medium-pressure decomposition, with the high-pressure condenser being a submerged condenser.
Such a process is described in for example GB-1.542.371.
According to that process a urea synthesis solution obtained in the urea synthesis reactor is thermally stripped in a high-pressure stripper. In the high-pressure stripper the ammonium carbamate and the remaining ammonia are removed from the urea synthesis solution by supplying heat. The gaseous products obtained during stripping 0 are subsequently condensed in a high-pressure condenser. The stripped urea synthesis solution is passed on to a medium-pressure decomposer wherein the ammonium carbamate still present is decomposed into CO2 and NH 3 The heat required for medium-pressure decomposition is supplied by steam condensate that is formed during high-pressure stripping of the urea synthesis solution.
High pressure here and hereinafter means a pressure of 12.5-20 MPa and medium pressure here and hereinafter means a pressure of 1.5-5 MPa.
Surprisingly, it has now been found that when in the aforesaid process a submerged condenser is used as high-pressure condenser, the steam A which forms in the high-pressure condenser has such a temperature and pressure that it can be utilized in combination with the steam condensate for medium-pressure decomposition of the ammonium carbamate in the urea synthesis solution.
Utilization of a combination of the steam condensate and steam A presents the advantage that at least a portion of the steam condensate becomes available for other purposes. This is because the steam condensate has a significantly higher S\Manla\FILES\AU PmskB31185 DSM831165 Amendd Pages 2201.09,doc temperature and pressure than needed for application in the medium-pressure decomposition. The steam condensate can be used to better effect elsewhere within or outside the urea process. Within the urea process the steam condensate could for example be expanded to a pressure of 1.2 MPa and then utilized for driving a vacuum ejector or for driving for example the CO 2 compressor, the NH 3 or the carbamate pumps.
The utilized quantities of steam condensate and of steam A depend on the temperature and pressure of the steam needed for medium-pressure decomposition.
More steam condensate is needed for a higher desired temperature S: ManlaTFILESEAU Pros\831165 DSM\31165 Amended Pages 22 01.09doc WO 03/064379 PCT/NLO2/00874 2 and pressure in the medium-pressure decomposition than for a lower desired temperature and pressure. The quantities of the steam condensate and of steam A are also dependent on the potential applications of the steam condensate within or outside the urea plant. If the steam condensate can be utilized for various other applications, it is of course advantageous for the quantity of steam A to be as large as possible.
Preferably, only steam A is used for the medium-pressure decomposition of the ammonium carbamate in the urea synthesis solution. This is possible since, where a submerged condenser is used, steam A in most cases has such a temperature and pressure as to be able to be utilized for the medium-pressure decomposition. In this manner it is also possible to utilize all steam condensate elsewhere.
Urea can be prepared by introducing excess ammonia together with carbon dioxide into a synthesis zone at a suitable pressure (for example 12-40 MPa) and suitable temperature (for example 160-250'C), which first results in the formation of ammonium carbamate according to the reaction: 2NH 3
CO
2
H
2
N-CO-ONH
4 Dehydration of the ammonium carbamate formed then results in the formation of urea according to the equilibrium reaction:
H
2
N-CO-ONH
4
H
2
N-CO-NH
2
H
2 0 The extent to which these reactions go to completion depends on inter alia the temperature and the excess amount of ammonia used. As a reaction product there is obtained a solution consisting essentially of urea, water, unbound ammonia and ammonium carbamate. The ammonium carbamate and the ammonia need to be removed from the solution and are preferably returned to the synthesis zone. Besides the aforementioned solution there arises in the synthesis zone also a gas mixture of unconverted ammonia and carbon dioxide as well as inert gases. Ammonia and carbon dioxide are removed from this gas mixture and are preferably also returned to the synthesis reactor.
Urea is prepared by means of for example a urea stripping process.
A urea stripping process is understood to be a process for the production of urea in WO 03/064379 PCT/NL02/00874 3 which the decomposition of the ammonium carbamate thatis not converted into urea and the expulsion of the customary excess ammonia largely take place at a pressure that is essentially virtually equal to the pressure in the synthesis reactor. This decomposition/expulsion takes place in one or more strippers located downstream of the synthesis reactor, for instance with addition of heat. The latter is called thermal stripping. Thermal stripping means that ammonium carbamate is decomposed and the ammonia and carbon dioxide present are removed from the urea solution exclusively by supplying heat. The ammonia and carbon dioxide-containing gas stream exiting from the stripper are condensed in a high-pressure carbamate condenser and returned to the reactor as an ammonium carbamate-containing stream.
Urea stripping processes usually employ two embodiments of a highpressure condenser for condensation of the stripping gases.
In a first embodiment, the gas mixture to be condensed, optionally in combination with a suitable solvent (for example a recirculated ammonium carbamate solution in water) is passed through vertical tubes, with the condensed gas mixture, whether or not in combination with the solvent, forming a falling film on the tube wall.
In a second embodiment, described in for example GB-1.542.371, the gases to be condensed, together with the solvent, flow through horizontally positioned tubes wherein the condensation process takes place.
In both of the aforementioned embodiments the required cooling is effected by passing a suitable coolant along the outside surface of the tubes. Water is usually used as a coolant.
A drawback of condensation in one of the two aforesaid embodiments of a highpressure condenser is that the liquid residence time in the tubes is short. Because of this short residence time, hardly any urea is formed in condensers according to the two aforesaid embodiments.
A third type of condenser is a so-called submerged condenser. A submerged condenser is described in for example EP-155735-A1. In a submerged condenser the gas mixture to be condensed is passed through the shell side of a shelland-tube heat exchanger, through which shell side may also be passed a dilute carbamrnate solution originating from for example the high-pressure scrubber. The heat of solution and condensation released here is removed with the aid of a medium, for example water, flowing through the tubes, which is converted into steam A.
In a urea plant, the high-pressure scrubber scrubs out of the inert stream the raw materials that are not converted in the reaction, which materials leave WO 03/064379 PCT/NL02/00874 4 the reactor through the top along with inert gases. Next the inert stream is vented.
Scrubbing is effected with the aid of a dilute carbamate stream which forms in the urea recovery section.
The submerged condenser may be placed in horizontal or vertical position. It is however particularly advantageous for condensation to be effected in a horizontal submerged condenser (also known as a pool condenser; see for example Nitrogen No. 222, July-August 1996, pages 29-31) in that, in comparison with other condenser designs, the liquid as a rule has a significantly longer residence time in the pool condenser. As a result, besides a carbamate solution, extra urea is formed in the pool condenser. This urea is returned to the urea reactor along with the carbamate solution.
A particular embodiment of a submerged condenser is a pool reactor.
Such a reactor comprises a horizontal condensation zone and heat exchanger that are designed as a submerged condenser. A proportion of the gas mixture to be condensed is passed through the shell side of a shell-and-tube heat exchanger, through which shell side the ammonia and a dilute carbamate solution are also passed, with the heat of solution and condensation being removed with the aid of a medium, usually water, which is converted into steam A.
A pool reactor has the advantage that the heat exchanger/condenser is integrated in the reactor, allowing a urea plant to be built at lower capital investment.
A pool reactor is described in further detail in US-5,767,313.
The condensation zone in the pool reactor has essentially the same advantages as a submerged condenser. In this condensation zone, too, urea formation takes place to a significant extent already in the condensation section, resulting in improved heat transfer as a result of which it is possible to produce in the condensation zone a steam A having such a pressure and temperature that it can be utilized in the mediumpressure decomposition.
Steam A has a temperature of 150-175 0 C, preferably of 160-170 0
C.
The steam A has a pressure of 0.3-1 MPa, preferably 0.4-0.8 MPa and most preferably 0.6-0.8 MPa.
The application of a submerged condenser, a pool condenser or a pool reactor is possible in a new urea plant that employs thermal stripping.
It is however also well possible in an existing urea plant employing thermal stripping to replace the existing condenser with a submerged condenser. This can take place during a regular maintenance shut-down of the plant. The existing condenser can also be replaced with a pool condenser. It is also possible in an existing urea plant to Cl replace both the reactor and the condenser with a pool reactor.
SAn example of a urea stripping process is the process as described in GB- 1.542.371.
In the urea stripping process as described in GB-1.542.371 high-pressure stripping of the urea synthesis solution is effected with the aid of steam having a Ci pressure of 26 atm (2,6 MPa) and a temperature of 2250C. This steam is used in the medium-pressure decomposition. In this stripping process, the steam produced by the rn, high-pressure condenser is not suitable for use in the medium-pressure decomposition, because this steam has a pressure of only 0.45 MPa and a C temperature of 1470C. Medium-pressure decomposition is effected at a pressure of approx. 1.8 MPa and a temperature of approx. 155TC.
If in the aforesaid process a submerged condenser is applied, steam A can be produced with a temperature of 160-170'C and a pressure of 0.6-0.8 MPa.
This steam A is suitable for use in the medium-pressure decomposition at a pressure of 1.8 MPa and a temperature of 1550C.
A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge as at the ?0 priority date of any of the claims.
Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereof.
SAP.Wanta'ILESAU Pms\831165 DSMW3 115 Aendod Page 22.01.09doc
Claims (9)
1. Process for the preparation of urea from carbon dioxide and ammonia by means of a urea stripping process comprising a high-pressure condenser and a high-pressure stripper, whereby a urea synthesis solution is formed and wherein the steam condensate that forms during high-pressure stripping of the c urea synthesis solution is utilized for medium-pressure decomposition of the ammonium carbamate in the urea synthesis solution, wherein a combination of q the steam condensate and steam A, which forms in the high-pressure condenser, or only steam A is used for medium-pressure decomposition, with N the high-pressure condenser being a submerged condenser.
2. Process according to Claim 1, wherein a pool condenser is used as submerged condenser.
3. Process according to Claim 1 or 2, wherein only steam A is used for medium- pressure decomposition.
4. Process according to Claim 1, wherein high-pressure condensation is effected ?0 in a pool reactor.
Process according to any one of Claims 1-4, wherein steam A has a temperature of 160-170'C.
6. Process according to any one of Claims 1-5, wherein steam A has a pressure of 0.6-0.8 MPa.
7. Urea when produced by a process according to Claim 1.
8. A process according to Claim 1 substantially as herein described or exemplified.
9. Urea according to Claim 7 substantially as herein described or exemplified. S:Aanta\FILESAU Pms\83115 DSM\8,31185 Amer5ed Pales 22.01.09 doc
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL1019848A NL1019848C2 (en) | 2002-01-28 | 2002-01-28 | Process for the preparation of urea. |
| NL1019848 | 2002-01-28 | ||
| PCT/NL2002/000874 WO2003064379A1 (en) | 2002-01-28 | 2002-12-30 | Process for the preparation of urea |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2002360227A1 AU2002360227A1 (en) | 2003-09-18 |
| AU2002360227B2 true AU2002360227B2 (en) | 2009-02-26 |
Family
ID=27656498
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2002360227A Ceased AU2002360227B2 (en) | 2002-01-28 | 2002-12-30 | Process for the preparation of urea |
Country Status (8)
| Country | Link |
|---|---|
| CN (1) | CN1260209C (en) |
| AR (1) | AR038220A1 (en) |
| AU (1) | AU2002360227B2 (en) |
| CA (1) | CA2473224C (en) |
| MY (1) | MY140851A (en) |
| NL (1) | NL1019848C2 (en) |
| RU (1) | RU2301798C2 (en) |
| WO (1) | WO2003064379A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1918273A1 (en) † | 2006-11-04 | 2008-05-07 | Urea Casale S.A. | Process for urea production and related plant |
| EA034717B1 (en) * | 2012-05-03 | 2020-03-12 | Стамикарбон Б.В. | Method for the production of urea from ammonia and carbon dioxide |
| GB201208312D0 (en) * | 2012-05-11 | 2012-06-27 | Afc Energy Plc | Fuel cell system |
| CN103570588A (en) * | 2013-08-30 | 2014-02-12 | 北京丰汉工程技术有限公司 | Urea synthesis device and urea synthesis method |
| JP7088770B2 (en) | 2018-07-26 | 2022-06-21 | 東洋エンジニアリング株式会社 | Urea production method and equipment |
| JP7157684B2 (en) | 2019-03-14 | 2022-10-20 | 東洋エンジニアリング株式会社 | Urea production method and apparatus |
| US12247002B2 (en) | 2019-03-14 | 2025-03-11 | Toyo Engineering Corporation | Process and apparatus for urea production |
| EP3736415A1 (en) * | 2019-05-10 | 2020-11-11 | Yara International ASA | Steam network assembly for a plant comprising an ammonia-producing unit and a urea-producing unit |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1068268B (en) * | 1976-09-09 | 1985-03-21 | Snam Progetti | PROCEDURE FOR THE PRODUCTION OF UREA AND PURIFICATION OF WATERS |
| NL1003923C2 (en) * | 1996-08-30 | 1998-03-04 | Dsm Nv | Process for the preparation of urea. |
-
2002
- 2002-01-28 NL NL1019848A patent/NL1019848C2/en not_active IP Right Cessation
- 2002-12-30 AU AU2002360227A patent/AU2002360227B2/en not_active Ceased
- 2002-12-30 RU RU2004126243/04A patent/RU2301798C2/en not_active IP Right Cessation
- 2002-12-30 CN CN 02827637 patent/CN1260209C/en not_active Expired - Lifetime
- 2002-12-30 WO PCT/NL2002/000874 patent/WO2003064379A1/en not_active Application Discontinuation
- 2002-12-30 CA CA2473224A patent/CA2473224C/en not_active Expired - Fee Related
-
2003
- 2003-01-10 MY MYPI20030081 patent/MY140851A/en unknown
- 2003-01-24 AR ARP030100209 patent/AR038220A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| CA2473224A1 (en) | 2003-08-07 |
| RU2301798C2 (en) | 2007-06-27 |
| NL1019848C2 (en) | 2003-07-30 |
| MY140851A (en) | 2010-01-29 |
| AR038220A1 (en) | 2005-01-05 |
| CA2473224C (en) | 2012-09-25 |
| CN1260209C (en) | 2006-06-21 |
| RU2004126243A (en) | 2006-01-27 |
| WO2003064379A1 (en) | 2003-08-07 |
| CN1617853A (en) | 2005-05-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FGA | Letters patent sealed or granted (standard patent) | ||
| PC | Assignment registered |
Owner name: STAMICARBON B.V. Free format text: FORMER OWNER WAS: DSM IP ASSETS B.V. |
|
| MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |