CN1036582C - Cheap, energy-saving, safety urea production process and its plant - Google Patents
Cheap, energy-saving, safety urea production process and its plant Download PDFInfo
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- CN1036582C CN1036582C CN93109664A CN93109664A CN1036582C CN 1036582 C CN1036582 C CN 1036582C CN 93109664 A CN93109664 A CN 93109664A CN 93109664 A CN93109664 A CN 93109664A CN 1036582 C CN1036582 C CN 1036582C
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- pressure
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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
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Abstract
The present invention relates to a cheap, energy-saving, safety urea production process and a device thereof. Ammonia and carbon dioxide are used as raw material. An air lifting reduction process is used, and a high pressure synthesis device, a condensing device, an absorption device, a low pressure decomposing and recovering device, a granulating device, etc. are used for producing urea. Liquid flown out of a stripper is decomposed at low pressure and is evaporated in a three-section way to obtain fusing urea which is delivered to be granulated. Thus, products are obtained. The stripper uses a Zr-lined heat exchange tube. Thus, the use level of anticorrosive air is less, and the conversion rate of the carbon dioxide is high. H2 is unnecessary to remove from the carbon dioxide, and tail gas is absorbed at high pressure and low pressure without explosive components. Thus, operation is safe. The tail gas and waste liquid are strictly treated, and then, are discharged. Thus, the present invention has no pollution for the environment. The present invention has the advantages of short technological process, low energy consumption, few equipment quantity, low investment, safe operation and convenient maintenance.
Description
The invention belongs to ammonia and carbonic acid gas is the chemical technique class of raw material production urea.
With ammonia and carbonic acid gas is that the method for raw material production urea is a lot, can be divided into water solution total cycling method and vaporizing extract process two big classes.Water solution total cycling method seldom adopts because technical process is long, equipment is many, investment is high, energy consumption is big.Now the vaporizing extract process production method that adopts is a lot, such as Dutch CTAMICARBON company is arranged, is called for short the STAC method, Japanese TOYOENGI NEERI NG company, be called for short the TEC method.
STAC method technology is seen Fig. 2, raw material CO
2Stripping tower 2 is delivered in compressed, combustion method dehydrogenation, with the synthetics counter current contact of urea synthesizer 1.Stripping gas and liquefied ammonia enter vertical high pressure condenser 3 condensations, and shell-side by-product 0.44MPa low-pressure steam is used for subsequent handling.Condensing air, liquid mixture enter urea synthesizer, and synthetic technological condition is: pressure 13.5MPa, 183 ℃ of temperature, charging NH
3/ CO
2Mol ratio=2.9, H
2O/CO
2Mol ratio=0.41.The liquid that comes out at the bottom of the gas stripping column is delivered to low pressure decomposition, flash distillation, vapo(u)rization system and is sent granulation to get product after decompression.43 is high pressure scrubber among the figure.
Because this technology stripping tower heat transfer tube adopts the CrNlMo25-22-2 material, requires steam stripping agent CO
2In higher O is arranged
2, add the dehydrogenation oxygen consumption, make a large amount of rare gas elementes import urea synthesizer, so CO
2Transformation efficiency is low, total conversion rate=51%, so need there be the high pressure scrubber condensation of band heat transfer tube to reclaim, many, the complex structure of high-tension apparatus, long flow path, investment height, energy consumption are big like this.
Fig. 3 is seen in the technical process of TEC method, contains O
2CO
2Send into stripping tower 3 bottoms, the solution of urea synthesizer 2 flow to stripping tower certainly at the bottom of tower.Stripping gas enters high pressure condenser 4, shell-side by-product 0.7MPa low-pressure steam, and it does not satisfy the subsequent handling needs, need add middle pressure steam.The synthesis process of urea condition is: pressure 17.2MPa, 190 ℃ of temperature, charging NH
3/ CO
2Mol ratio=4, H
2O/CO
2Mol ratio=0.64.Synthetic gas is through high pressure scrubber 5, with stripping tower bottom outlet liquid after medium voltage network is sent in decompression, send into lp system again and enter subsequent handling again.Though this technology CO
2The transformation efficiency height, total conversion rate reaches 67-68%, but decomposes and recovery system because of pressing in must being provided with, also exist long flow path, equipment many, invest high problem.
The objective of the invention is the problem that exists according to above-mentioned technology, be intended to design a kind of energy consumption, low, reduced investment, manipulate safety, environment do not had substantially the urea production process of harm.
The objective of the invention is to realize in the following manner, energy-conservation, joint money, safety type urea production process and device, the liquefied ammonia of purity 〉=99.5% (weight), pressure 〉=1.5MPa, temperature 〉=15 ℃ boosts to 17.7MPa through ammonia pump, through ammonia well heater 1, deliver to high pressure condenser 5 by high-pressure injector 2, raw material CO
2Gas is through CO
2Compressor pressurizes is sent into the synthetics counter current contact that steam stripping agent and urea synthesizer 3 are made in stripping tower 4 bottoms to 16MPa, and first ammonium is wherein decomposed and the NH that dissociates
3Overflow, stripping gas then enters high pressure condenser 5.The gas-liquid mixture that comes out from the high pressure condenser of horizontal layout enters urea synthesizer 3 and carries out urea synthesis, and the synthesis process of urea operational condition is: pressure 15.2-16.2MPa, temperature 188-192 ℃, charging NH
3/ CO
2Mol ratio=3.0-3.2, H
2O/CO
2Mol ratio=0.40-0.50, synthetic liquid flows automatically to stripping tower, and stripping tower heat transfer tube material is a CrNlMo25-22-2 liner zirconium thin-walled.
Contain small amount of N H
3And CO
2The urea synthesizer exit gas flow into the high-pressure absorber 6 that is arranged in tower bottom, the first ammonium liquid that comes with the pumping of first ammonium absorbs washing, establish the low pressure decomposition tower 7 of three blocks of valve traies in delivering to, from the urea first ammonium liquid of stripping tower bottom earlier the upper space flash distillation with separate, solution flow to falling film type decomposition heater 8 thermal degradation downwards, and the working pressure of low pressure decomposition tower is 0.3-0.35MPa.
The urine that goes out decomposition heater 8 enters first vapor seperator, 13 flash separations that pressure is 0.045MPa after decompression, liquid phase flows into falling film type first vaporizer epimere 11 and hypomere 12, under 0.045MPa pressure, vent one's spleen and stripping gas is made thermal source with dividing respectively, urine is concentrated into 75-80%.Deliver to second vaporizer 14 through urine pump 18, under 0.033MPa pressure, make thermal source with the 0.4-0.5MPa low-pressure steam, urine is concentrated into 95-96%, again through second vapor seperator 15, isolate urine and flow to the 3rd vaporizer 16, under 0.033MPa pressure, make thermal source with 0.6-0.9MPa steam, urine is concentrated into 99.7-99.8%, again through the 3rd vapor seperator 17, to prilling tower 20, granulation gets product by 19 dozens of melt urea pumps.
Content of the present invention is described in detail in detail with reference to the accompanying drawings.
Fig. 1 process flow sheet of the present invention
Fig. 2 STAC method process flow sheet
Fig. 3 TEC method process flow sheet
With reference to Fig. 1, high pressure condenser is horizontal U type heat transfer tube one useless shell side type clustered aggregates, pipe side working pressure 15.2-16.2MPa, condensing temperature 166-172 ℃, NH
3, CO
2, H
2O condensation in high pressure condenser 5, its degree of condensation are by shell-side byproduct steam pressure-controlling, and the low-pressure steam of by-product 0.4-0.5MPa is used for subsequent handling, accomplish to produce and use balance.At the tube sheet of horizontal heat exchanger shell-side and the gap location of pipe compartment, be full of steam condensate, make chlorion concentrate and gather in the place, crack during this time, eliminated the corrosion that produces by chlorion, improved security and life-span that equipment uses.
The solution-air phase mixture of high pressure condenser enters urea synthesizer 3 from the bottom, and mobile from bottom to top, and the dehydration of first ammonium generates urea in the liquid phase, and the continuous condensation of gas phase is emitted heat and used for dehydration of first ammonium and material intensification.Tower liner CrNlMo25-22-2 or 316L urea level material, the centre is provided with 10 blocks of column plates with holes, and material is only upwards flowed in tower, prevents back-mixing, improves CO
2Transformation efficiency, its total CO
2Transformation efficiency 62-64%, CO in the liquid phase
2Transformation efficiency=64-67%.Urea synthesis solution flows automatically to stripping tower 4 by interior upflow tube, and gas flows into high-pressure absorber 6.
The heat transfer tube of stripping tower adopts CrNlMo25-22-2 liner thin-walled, the wall thickness 0.6-1.0mm zirconium pipe of anti-physics corrosion and chemical corrosion, long service life, and simultaneously because zirconium has anti-urea first ammonium corrosion performance under the high temperature, so CO
2The O that only need contain 0.1-0.25% (volume) in the unstripped gas
2Thereby, greatly reduce CO
2In amount of inert gas, saved CO
2The compression energy consumption has been optimized the urea synthesis parameter.Produce urea per ton, provide 1.255GJ heat to stripping tower.
Stripping tower working pressure 15.2-16.2MPa, shell-side 2.0-2.5MPa steam heating.Tower bottom is provided with a porous plate, increases the gas-liquid heat-transfer effect, reduces liquid temp, reduces the growing amount of hydrolysis of urea rate and biuret.188-190 ℃ of exhaust gas phase temperature, liquid phase 160-170 ℃, ammonia stripping rate 76-80%.
Be provided with three sieve plates and a gas passage pipe in the high-pressure absorber 6.Have small amount of N H
3And CO
2Synthetic gas enter lower concentration first ammonium liquid (70-80 ℃) washing that comes with the pumping of first ammonium in the tower and absorb, absorbed dose then enters low pressure decomposition tower 7 by the gas passage management and control system in the tower.O in the exhaust gas body
2Content is less than 4%, no explosion hazard.
Three blocks of valve traies are set in the low pressure decomposition tower, at first carry out flash distillation and separate at upper space from the urea first ammonium liquid of stripping tower.Solution hot gas with decomposition heater on column plate carries out mass-and heat-transfer, and solution flow to falling film type decomposition heater 8 downwards, and shell-side heats with low-pressure steam, provides the first ammonium to decompose institute's heat requirement.
The gas that goes out the low pressure decomposition tower enters the first vaporizer epimere 11, enters low-pressure condenser 9 behind the recovery part heat, and low-pressure condenser is horizontal bubbling immersion type, at this, and NH
3-CO
2-H
2Condensation takes place and generates 70-80 ℃ of first ammonium liquid in O, emits heat and is removed a small amount of uncooled NH by the airtight warm water recycle system of shell-side
3-CO
2Enter low pressure absorption tower 10 with other rare gas element,, contain NH hardly with ammoniacal liquor and cold steam condensate washing
3Rare gas element enter atmosphere, almost pollution-free to environment.Emptying H
2-N
2-O
2O in the mixed gas
2Content is also low, no explosion hazard.
First, second, third vapor seperator exit gas all contains NH
3-CO
2-H
2O and carry a small amount of urea secretly enters vacuum system separately respectively.Vacuum system comprises surface condenser (symbol O among the figure), steam injector, and (symbol 1 among the figure, is used for condensation and reclaims NH
3-CO
2-urea forms needed vacuum tightness.The order of each gas is: 13-41-42-39,15-40-42-39,17-34-36-37-38-39, the gas after condensation is reclaimed is from surface condenser 39 emptying.
The process condensate of each vacuum system all flow to ammonia vessel 22, and desorb feeding pump 23 is delivered to first desorption tower 25 by way of desorb interchanger 24 backs from the top with the ammoniacal liquor pressurization, contains NH after the desorb
3-urea soln is boosted by hydrolysis feeding pump 27 and enters horizontal hydrolyzer 29 by way of hydrolysis interchanger 28.Be in series with several hydrolysis unit in the horizontal hydrolyzer, working pressure is that the steam distribution pipe of 2.0-4.0MPa is to each hydrolysis unit needed heat of hydrolysis of supplying urea.The solution that comes out from last unit of hydrolyzer does not almost have urea to exist, and delivers to second desorption tower, 26 tops after decompression, uses the low-pressure steam direct heating at the bottom of the tower, NH the water that comes out at the bottom of the tower
3With urea content all less than 5ppm, after desorb interchanger 24 reclaims heats, be sent to and make boiler water-filling outside the battery limit (BL).Aqua ammonia pump 33 is delivered to low pressure absorption tower 10 with ammoniacal liquor.
From the stripping gas that comes out in first desorption tower, 25 tops, contain NH
3-CO
2-H
2O delivers to and imports desorb condenser 30 again behind the first vaporizer hypomere, the 12 recovery part heats and carry out last condensation.The desorb condenser is vertical submerged condenser, and uncooled micro-rare gas element washs back emptying with steam condensate in level tank 31.The desorb phlegma is delivered to the first evaporation heater epimere, 11 shell-sides by desorb condensate pump 32.
High pressure loop equipment layout mode of the present invention is: urea synthesizer is positioned at the top of stripping tower, and absolute altitude is similar to urea synthesizer cylindrical shell lower cover tangent line absolute altitude at the bottom of the high pressure condenser shell-side, and high-pressure absorber is arranged in and the same floor absolute altitude of each vaporizer place.
Stripping tower of the present invention adopts lining zirconium heat transfer tube, and long service life also can reduce raw material CO
2In the anticorrosion O that uses
2, can be at NH
3/ CO
2Obtain high CO under low situation and suitable pressure, the temperature
2Transformation efficiency, high pressure condenser, high and low pressure absorption tower deft design, operational safety, no explosion hazard.No raw material CO in the technical process
2Dehydrogenation operation, high pressure loop equipment adopt low frame arrangement, and high-pressure absorber does not need airtight hot water cyclesystem, press in need not and decompose a circulation recovery process, so technical process of the present invention is short, energy consumption is low, number of devices is few, reduced investment, operational administrative, maintenance safe ready.
Claims (4)
1, urea production process, the liquefied ammonia of purity 〉=99.5% (weight), pressure 〉=1.5MPa, temperature 〉=15 ℃ boosts to 17.7MPa through ammonia pump, through ammonia well heater (1), deliver to high pressure condenser (5), raw material CO by high-pressure injector (2)
2Gas is through CO
2Compressor pressurizes is sent into stripping tower (4) bottom to 16MPa and is made steam stripping agent, with the synthetics counter current contact that urea synthesizer (3) comes, first ammonium is wherein decomposed and the NH that dissociates
3Overflow, stripping gas then enters high pressure condenser (5), contains small amount of N H
3And CO
2The urea synthesizer exit gas flow into the high-pressure absorber (6) that is arranged in tower bottom, the first ammonium liquid that comes with the pumping of first ammonium absorbs washing, the urine that goes out decomposition heater (8) is sent into evaporator evaporation after decompression, separate, isolated urine is concentrated into 99.7-99.8%, deliver to the granulation of prilling tower jacking row then, under prilling tower, obtain product, it is characterized in that entering urea synthesizer (3) from the gas-liquid mixture that the high pressure condenser of horizontal layout comes out carries out urea synthesis, the synthesis process of urea operational condition is: pressure 15.2 one 16.2MPa, temperature 188-192 ℃, charging NH
3/ C
2Mol ratio=3.0-3.2, H
2O/CO
2Mol ratio=0.40-0.50, synthetic liquid flows automatically to stripping tower, urea first ammonium liquid from the stripping tower bottom is delivered to low pressure decomposition tower (7), earlier the upper space flash distillation with separate, solution flow to falling film type decomposition heater (8) thermal degradation downwards, the working pressure of low pressure decomposition tower is 0.3-0.35MPa
The stripping tower fluid is through the low pressure decomposition tower with after decomposing heating, decompression enters first vapor seperator (13) flash separation that pressure is 0.045MPa, liquid phase flows into falling film type first vaporizer epimere (11) and hypomere (12), under 0.45MPa pressure, vent one's spleen and stripping gas is made thermal source with dividing respectively, urine is concentrated into 75-80%, deliver to second vaporizer (14) through urine pump (18), under 0.033MPa pressure, make thermal source with the 0.4-0.5MPa low-pressure steam, urine is concentrated into 95-96%, again through second vapor seperator (15), isolate urine and flow to the 3rd vaporizer (16), under 0.033MPa pressure, make thermal source with 0.6-0.9MPa steam, urine is concentrated the back granulation.
2, technology according to claim 1 is characterized in that stripping tower (4) working pressure 15.2-16.2MPa, shell-side 2.0-2.5MPa steam heating, raw material CO
2In contain O20.1-0.25% (volume), 188-190 ℃ of exhaust gas phase temperature, liquid phase 160-170 ℃, ammonia stripping rate 76-80%.
3, urea plant, it is characterized in that high pressure condenser (5) is horizontal U type heat pipe-useless shell side type clustered aggregates, establish three blocks of valve traies in the low pressure decomposition tower (7), be provided with three sieve plates and a gas passage pipe in the high-pressure absorber (6), low-pressure condenser is horizontal bubbling immersion type, and shell-side adopts the airtight warm water recycle system to remove heat.
4, device according to claim 3 is characterized in that high pressure condenser (5) pipe side working pressure is 15.2-16.2MPa, condensing temperature 166-172 ℃, and shell-side by-product 0.4-0.5MPa steam.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN93109664A CN1036582C (en) | 1993-08-02 | 1993-08-02 | Cheap, energy-saving, safety urea production process and its plant |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN93109664A CN1036582C (en) | 1993-08-02 | 1993-08-02 | Cheap, energy-saving, safety urea production process and its plant |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1086511A CN1086511A (en) | 1994-05-11 |
| CN1036582C true CN1036582C (en) | 1997-12-03 |
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ID=4987719
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN93109664A Expired - Fee Related CN1036582C (en) | 1993-08-02 | 1993-08-02 | Cheap, energy-saving, safety urea production process and its plant |
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| ITMI20061223A1 (en) * | 2006-06-26 | 2007-12-27 | Snam Progetti | BIMETALLIC PIPE RESISTANT TO CORROSION AND ITS USE IN TUBIWERO BAND EQUIPMENT |
| CN101823984B (en) * | 2010-04-29 | 2012-11-28 | 聊城市鲁西化工工程设计有限责任公司 | Process and device for reclaiming hydrolysis desorption heat energy |
| CN102336688B (en) * | 2011-07-05 | 2013-09-25 | 浠水县福瑞德化工有限责任公司 | Urea process water circulation system and method |
| CN103827081B (en) * | 2011-08-17 | 2016-06-01 | 斯塔米卡邦有限公司 | The urea preparation method that fusing urea time of delivery between last thickener and prilling tower is short |
| CN104341321B (en) * | 2013-07-25 | 2016-04-13 | 新煤化工设计院（上海）有限公司 | A kind of preparation method of urea for vehicle |
| CN104557616B (en) * | 2014-12-22 | 2016-06-22 | 嵊州领航信息科技有限公司 | A kind of method of urea synthesis solution |
| CN104591807A (en) * | 2014-12-22 | 2015-05-06 | 广西大学 | Preparation technology for extracting ammonia from urine to synthesize urea |
| CN104529829B (en) * | 2014-12-22 | 2016-06-15 | 嵊州领航信息科技有限公司 | A kind of method of urea synthesis |
| EP3398935A1 (en) * | 2017-05-05 | 2018-11-07 | Casale Sa | Process and plant for the synthesis of urea |
| CN107759493A (en) * | 2017-09-28 | 2018-03-06 | 刘金成 | A kind of method of free ammonia in removal carbamide dust |
| CN110776029A (en) * | 2019-10-28 | 2020-02-11 | 天津农学院 | Multi-effect evaporation treatment system and process for low-boiling-point oil-containing wastewater |
| CN115466200A (en) * | 2022-10-24 | 2022-12-13 | 上海超希实业有限公司 | High-quality synthetic urea processed by sectional control reaction and processing method |
| CN116658881B (en) * | 2023-07-26 | 2023-09-26 | 上海优华系统集成技术股份有限公司 | Residual heat steam generating system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1035109A (en) * | 1988-02-08 | 1989-08-30 | 斯塔米卡本公司 | The method for preparing urea |
| CN1067425A (en) * | 1992-05-30 | 1992-12-30 | 化学工业部第四设计院 | Energy-saving technology for production of urea |
-
1993
- 1993-08-02 CN CN93109664A patent/CN1036582C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1035109A (en) * | 1988-02-08 | 1989-08-30 | 斯塔米卡本公司 | The method for preparing urea |
| CN1067425A (en) * | 1992-05-30 | 1992-12-30 | 化学工业部第四设计院 | Energy-saving technology for production of urea |
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| Publication number | Publication date |
|---|---|
| CN1086511A (en) | 1994-05-11 |
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