CN1141294C - Method of recovering dehydrogenation heat energy in urea production - Google Patents
Method of recovering dehydrogenation heat energy in urea production Download PDFInfo
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- CN1141294C CN1141294C CNB011284994A CN01128499A CN1141294C CN 1141294 C CN1141294 C CN 1141294C CN B011284994 A CNB011284994 A CN B011284994A CN 01128499 A CN01128499 A CN 01128499A CN 1141294 C CN1141294 C CN 1141294C
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- 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
- Y02P20/10—Process efficiency
Abstract
The present invention relates to a method for recovering dehydrogenation heat energy in urea production. A heat energy recovery heat exchanger is additionally arranged in an outlet of a dehydrogenation reactor for raw material gas of CO2, and boiler supply water is used as a coolant or the raw material gas of CO2 after desulphurized before dehydrogenated is used as a coolant to recover reaction heat for removing H2 and partial gas compression heat. When the boiler supply water is used as the coolant, the by-product is 0.4 to 0.5MPa (by a meter) of steam or 150 to 180 DEG C of high-temperature hot water, and the gas removing H2 is cooled to 100 to 120 DEG C by a high-pressure ring for removing urea or cooled to 160 to 180 DEG C by a cooler of a centrifugal compressor. When the raw material gas of CO2 after desulphurized and before dehydrogenated is used as the coolant, the raw material gas is introduced into the dehydrogenation reactor after heated, the dehydrogenated gas is cooled to 60 DEG and cooled to 40 to 45 DEG C by a medium pressure CO2 cooler, and the gas returns a third section or a fourth section of the compressor to be pressurized by the urea high-pressure ring after the steam and the water are separated. The method of the present invention is adopted by urea factories having the yield of 520, 000 tons per year, and the by-product of 10, 000 tons of 0.4 to 0.5MPa (by a meter) of steam is produced per year.
Description
Technical Field
The invention relates to a method for recovering heat energy of dehydrogenation reaction in the process of urea production.
Background
To prevent corrosion of stainless steel and titanium lined equipment and piping for urea production, it is necessary to feed the urea with CO2Or NH3Adding O with the volume of 0.2-0.8% of the raw material gas2Added in the form of air. Due to the raw material CO2The gas contains H2、CH4、CO、CH3OH and other combustible components, and the combustible gases can be accumulated in high-pressure or medium-pressure tail gas in urea production to cause explosion, so that a plurality of explosion accidents occur in urea production plants at home and abroad. At present, to avoid H in the tail gas2When the accumulation of combustible gases falls in the explosion zone, it is accepted to prevent H from using a dehydrogenation catalyst2Isocombustible component and O2A combustion reaction occurs to convert H2The removal is carried out to below the explosion limit, thereby greatly improving the safety of the production process.
Current urea production de-H2Flow, typically high pressure de-H from Stramikapont2Flow and medium pressure dehydrogenation flow. De-H in high pressure dehydrogenation flow2Reaction ofThe device is located in CO2The outlet gas pressure at the final stage outlet of the compressor is 13-15MPa, the temperature is 100-2The temperature of the gas at the inlet of the reactor reaches the activation temperature of the platinum catalyst, so that high-pressure CO is set2A heater for heating with steam to remove H2High temperature CO of reactor2The gas is again at high pressure CO2Cooling to 100-120 deg.C in cooler and feeding into CO produced by urea2Stripping tower, thereby consuming cooling water again, thus removing H for every 1 ton of urea produced2The unit consumes 20-40kg of medium pressure steam and 3-6m of cooling water3. Removal of H at medium pressure2In the process, H is removed2The reactor being located in a centrifugal CO2And a second-stage outlet of the compressor. High temperature CO at two stage outlet2Gas directly enters into and is removed from H2Reactor, removing H2The high-temperature gas in the reactor is sent to a two-stage gas cooler of a compressor. Medium pressure dehydrogenation H2Only one process is used for removing H2The reactor does not consume steam, but the two-stage gas cooler needs to consume more cooling water.
The high pressure removal of H2Flow and Medium pressure dehydrogenation H2The defect of the flow is the removal of H2The heat of reaction is not effectively utilized and is wasted.
Removing H2The process had the following exothermic reaction:
when CO is present2The feed gas component has a dry volume% of 98.5CO2；1.0H2；0.1CO；100×10-6CH4；300×10-6CH3When OH is present, H is removed2The chemical reaction heat is 50650KJ/t urea, 19kg0.5MPa (shown as a by-product) saturated steam can be produced, and 52 ten thousand tons of urea plants can be produced in 1 year, so that more than 1 ten thousand tons of urea can be recoveredThe steam per ton has considerable economic value.
Disclosure of Invention
The invention aims to overcome the defect of H removal in the prior urea production2The defect of the process provides a process for removing H in the urea production process2A method for recovering heat energy.
The invention aims to realize the H removal in the urea production2The method for recovering heat energy is in CO2The outlet of the raw material gas dehydrogenation reactor is additionally provided with a heat energy recovery heat exchanger, boiler feed water is used as a coolant or CO after desulfurization and before dehydrogenation is used2The raw material gas is used as a coolant for recovering and removing H2Heat of reaction and part of the heat of gas compression. When boiler feed water is used as coolant, the byproduct steam is 0.4-0.5MPa (table) or 150-180 deg.C high temperature hot water to remove H2The gas is cooled to 100-120 ℃ to remove the urea high-pressure ring, or cooled to 160-180 ℃ to remove the urea high-pressure ring from the centrifugal compressor inter-segment cooler; with CO after desulfurization and before dehydrogenation2When the raw material gas is used as coolant, the raw material gas is heated and then is removed from a dehydrogenation reactor, the dehydrogenation gas is cooled to 60 ℃, and then is subjected to medium-pressure CO2The cooler is cooled to 40-45 ℃, and the urea high-pressure ring is removed after the steam-water separation and the pressurization of the 3 or 4 sections of the compressor.
The heat energy recovery heat exchanger is a horizontal U-shaped tube heat exchanger, boiler feed water at normal temperature of 98 ℃ below zero is used as a coolant, and byproduct steam is 0.4-0.5MPa (shown).
The heat energy recovery heat exchanger uses a horizontal tube type heat exchanger, and uses boiler feed water at normal temperature of 98 ℃ below zero as a coolant to produce high-temperature water at 180 ℃ and 150 ℃.
Themethod can effectively recover the heat of dehydrogenation reaction and recover CO introduced and returned between compressor sections2Gas temperature difference heat (temperature 40-60 ℃).
Drawings
FIG. 1 is a high pressure de-H process of the present invention2A heat energy recovery process flow chart.
FIG. 2 is a medium pressure dehydrogenation of H in the process of the present invention2A process flow chart of heat energy recovery byproduct steam.
FIG. 3 is a medium pressure dehydrogenation of H in the process of the present invention2A process flow chart of heat energy recovery and by-product high-temperature hot water.
FIG. 4 is a medium pressure dehydrogenation of H in the process of the present invention2A heat energy recovery energy-saving process flow chart.
In the figure, the reference number is 1-1 multistage compressor, 1-2 centrifugal compressor, 2 auxiliary heater and 3H removal2The system comprises a reactor, 4 heat energy recovery heat exchangers, 4-1 horizontal U-shaped heat exchangers, 4-2 horizontal tubular heat exchangers, 5 start-up heaters, 6 interstage cooling separators, 7 oil removal and desulfurization tanks, 8 medium-pressure CO2A cooler, a 9 gas-water separator, 10 boiler feed water, 11 byproduct steam, 12 byproduct hot water, 13 steam and 14 condensate.
Detailed Description
The method of the present invention is further illustrated below with reference to the accompanying examples.
Example 1
The design is as shown in figure 1 for high-pressure removal of H in urea production2And (4) a heat energy recovery process flow. CO 22Raw material gas is added for corrosion prevention and H removal2By air (CO for short hereinafter)2Gas) enters a multistage compressor 1-1, and the pressure of the gas after multistage compression and the CO at the final stage is 14-18MPa and the temperature is 110-2Gas, entering the auxiliary heater 2, heating the CO with steam 132Gas, to make it attain the dehydrogenation of platinum and palladium2Initial reaction temperature of catalyst, in-and-out of H2Reactor 3 for removing H2Removing H2Post CO2The temperature of the gas is increased, and the boiler feed water 10 with the normal temperature of 98 ℃ is used as a coolant in the heat energy recovery heat exchanger 4 to lead CO to be generated2The gas temperature is reduced to 100-120 ℃ and is sent to a high-pressure ring of the urea production device. Boiler feed water 10 is heated by a heat exchanger 4 to be 0.4-0.5MPa (table) steam 11 and is sent out, or is heated to be 160-180 ℃ high-temperature hot water 12 and is sent out to users.
Example 2
The design is as shown in figure 2 for medium pressure stripping H in urea production2And (4) a heat energy recovery process flow. CO 22The gas is led out from 2 or 3 sections of the centrifugal compressor 1-2 at pressure2-3.2MPa, temperature 100-2Gas is introduced into the auxiliary heater 2 to raise the temperature thereof to a temperature for removing H2Initial temperature of reaction, in-and-out of H2Reactor 3, removing H2The high-temperature gas in the reactor 3 exchanges heat with boiler feed water 10 at the normal temperature of 98 ℃ in a heat energy recovery horizontal U-shaped heat exchanger 4-1 to produce steam 11 with the pressure of 0.4-0.5MPa (shown in the table) to be sent to a user, and CO discharged from the heat energy recovery heat exchanger 4-12The gas temperature is reduced to 160 ℃ and 180 ℃, and the gas returns to enter the cooler between 2 or 3 sections of the centrifugal compressor 1-2.
When the centrifugal compressor 1-2 is provided with an outlet CO2When the gas temperature is higher than 180 ℃, the auxiliary gas is not neededAnd a heater 2.
Example 3
The design is as shown in figure 3 for medium pressure stripping H in urea production2A process flow of heat energy recovery and by-product high-temperature hot water. CO 22The gas is led out from the 2 or 3 sections of the centrifugal compressor 1-2, the pressure is 2-3.2MPa (absolute), and the temperature is 100-2The gas is heated in the auxiliary heater 2 to remove H2After the initial temperature of the reaction, H is removed2 Reactor 3 for removing H2Removing H2The gas is cooled to 100-plus-120 ℃ by normal temperature-98 ℃ and boiler feed water 10 in the heat energy recovery horizontal tubular heat exchanger 4-2, and then returns to the 2-or 3-segment inter-cooler of the centrifugal compressor 1-2, and the boiler feed water 10 absorbs heat in the heat exchanger and is heated to 150-plus-170 ℃ high-temperature hot water 12 and then is sent to users.
When the centrifugal compressor 1-2 discharges CO2When the gas temperature is higher than 180 ℃, the auxiliary heater 2 is not needed.
The flow of the embodiment not only recovers the de-H2The heat of reaction and the recovery of CO between compressor stages leading and returning to the compressor2The heat difference of the gas is 40-60 ℃, and the heat is larger than the heat for removing H2The heat of reaction is very valuable.
Example 4
The design is as shown in figure 4, the medium-pressure energy-saving type H removal is carried out in the urea production2The process flow is as follows. CO out of reciprocating compression 1-1 two-stage or three-stage2The gas is separated by an intersegment cooling separator 6 to discharge condensed water and oil, and then further deoiled and desulfurized by an oil-removing desulfurizing tank 7Desulfurization to protect against H removal2Catalyst, CO at this time2Gas temperature lower than 40 ℃, as a coolant and in-out H in the heat energy recovery heat exchanger 42High temperature dehydrogenation of reactor 32Gas heat exchange, and temperature rise to H removal2Initial reaction temperature of catalyst for H removal2Reactor 3, removing H2After CO2The temperature of the gas is reduced to 60 ℃ through a heat energy recovery heat exchanger 4, and then the gas is subjected to medium pressure CO2The cooler 8 is cooled to 40-45 ℃ by cooling water, and then the water is separated by the gas-water separator 9 and returns to the three or four sections of the compressor. The start-up heater 5 in the process is used for the start-up production condition, and is used for removing H under the normal production condition2After CO2Gas heating for entering and removing H2CO of the reactor2Raw material gas, no steam consumption.
Claims (3)
1. A process for recovering the heat energy generated by dehydrogenation in urea production features that the CO is used as the carrier2The outlet of the raw material gas dehydrogenation reactor (3) is additionally provided with a heat energy recovery heat exchanger (4), boiler feed water is used as a coolant or CO is used after desulfurization and before dehydrogenation2The raw material gas is used as a coolant for recovering and removing H2Reaction heat and partial gas compression heat, when boiler feed water (10) is used as a coolant, the byproduct steam (11) is 0.4-0.5MPa (table) or 150-180 ℃ high-temperature hot water (12) to remove H2The gas is cooled to 100-120 ℃ to remove the urea high-pressure ring, or cooled to 160-180 ℃ to remove the cooler (6) between the centrifugal compressor sections; with CO after desulfurization and before dehydrogenation2When the raw material gas is used as a coolant, the raw material gas is heated and then is removed from a dehydrogenation reactor (3), the dehydrogenation gas is cooled to 60 ℃, and then is subjected to medium-pressure CO2The cooler (8) is cooled to 40-45 ℃, and the urea high-pressure ring is removed after the gas-water separator (9) separates and returns to the 3 or 4 sections of the compressor (1-1) for pressurization.
2. The dehydrogenation heat energy recovery method according to claim 1, wherein the heat energy recovery heat exchanger is a horizontal U-shaped tube heat exchanger (4-1), boiler feed water (10) at normal temperature of-98 ℃ is used as a coolant, and the byproduct steam (11) is 0.4-0.5MPa (table).
3. The dehydrogenation heat energy recovery method according to claim 1, characterized in that a horizontal tubular heat exchanger (4-2) is adopted, and boiler feed water (10) at normal temperature-98 ℃ is used as a coolant to produce high-temperature water (12) at 180 ℃ in the range of 150-.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011284994A CN1141294C (en) | 2001-09-27 | 2001-09-27 | Method of recovering dehydrogenation heat energy in urea production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011284994A CN1141294C (en) | 2001-09-27 | 2001-09-27 | Method of recovering dehydrogenation heat energy in urea production |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1344710A CN1344710A (en) | 2002-04-17 |
| CN1141294C true CN1141294C (en) | 2004-03-10 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB011284994A Expired - Lifetime CN1141294C (en) | 2001-09-27 | 2001-09-27 | Method of recovering dehydrogenation heat energy in urea production |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| NO2749379T3 (en) * | 2012-04-16 | 2018-07-28 | ||
| CN104302575B (en) * | 2012-04-16 | 2017-03-22 | 赛尔斯通股份有限公司 | Method for producing solid carbon by reducing carbon dioxide |
| CN106748889B (en) * | 2016-12-30 | 2018-04-06 | 安徽昊源化工集团有限公司 | Dehydrogenation heat-energy recovering apparatus in urea production |
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- 2001-09-27 CN CNB011284994A patent/CN1141294C/en not_active Expired - Lifetime
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Owner name: HUASHUO SCIENCE AND TECHNOLOGY CO., LTD. Free format text: FORMER NAME: HUBEI CHEMICAL RESEARCH INSTITUTE |
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Address after: No. 30 Guan Shan Road, Hongshan District, Hubei, Wuhan Patentee after: Huashuo Technology Co., Ltd. Address before: No. 30 Guan Shan Road, Hongshan District, Hubei, Wuhan Patentee before: Hubei Research Institute of Chemistry |
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Assignee: Hubei Sanning Chemical Co., Ltd. Assignor: Huashuo Technology Co., Ltd. Contract record no.: 2010420000117 Denomination of invention: Method of recovering dehydrogenation heat energy in urea production Granted publication date: 20040310 License type: Exclusive License Open date: 20020417 Record date: 20100812 |
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Denomination of invention: Method of recovering dehydrogenation heat energy in urea production Effective date of registration: 20100907 Granted publication date: 20040310 Pledgee: Bank of Hankou, Limited by Share Ltd, Optics Valley branch Pledgor: Huashuo Technology Co., Ltd. Registration number: 2010990000869 |
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Date of cancellation: 20151106 Granted publication date: 20040310 Pledgee: Bank of Hankou Limited by Share Ltd Optics Valley branch Pledgor: Huashuo Technology Co., Ltd. Registration number: 2010990000869 |
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Change date: 20151106 Registration number: 2010990000869 Pledgee after: Bank of Hankou Limited by Share Ltd Optics Valley branch Pledgee before: Bank of Hankou, Limited by Share Ltd, Optics Valley branch |
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