CN102816091A - Aqueous solution full-cycle urea energy-saving production process - Google Patents

Aqueous solution full-cycle urea energy-saving production process Download PDF

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CN102816091A
CN102816091A CN2011101561531A CN201110156153A CN102816091A CN 102816091 A CN102816091 A CN 102816091A CN 2011101561531 A CN2011101561531 A CN 2011101561531A CN 201110156153 A CN201110156153 A CN 201110156153A CN 102816091 A CN102816091 A CN 102816091A
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urea
tower
aqueous solution
ammonia
energy
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王光荣
孙超
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ANHUI KEJIE RENEWABLE ENERGY Co Ltd
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ANHUI KEJIE RENEWABLE ENERGY Co Ltd
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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
    • 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 invention relates to an aqueous solution full-cycle urea energy-saving production process. The aqueous solution full-cycle urea energy-saving production process comprises a high pressure synthesis step, a recycling step, an evaporation step and a desorption and hydrolysis step, wherein the a high pressure synthesis step comprises enabling raw material liquid ammonia from an ammonia tank to be sent through a liquid ammonia pump to a liquid ammonia preheater to be heated and divided into two paths, enabling one path to enter a tower top distributor of a synthesis tower, enabling the other path to enter the urea synthesis tower to undergo an isothermal high-pressure synthesis reaction, and enabling a reaction product to be out of the tower top; the recycling step comprises enabling the discharged reaction mixture to undergo medium-pressure and low-pressure decomposition absorption and then be sent into an evaporation system, and enabling tail gas to be vented after ammonia cleaning treatment; the evaporation step comprises performing preconcentration on urea solution from a low-temperature circulating system, utilizing expansion steam and steam condensate to perform heating reconcentration on the preconcentrated urine, and sending the urine to a urea granulation tower; and the desorption and hydrolysis step comprises pumping ammonium bicarbonate liquid to a desorption and hydrolysis system, and enabling content of urea and ammonia in desorbed cleaned water discharged out of the tower bottom to be no larger than 5ppm. Compared with the prior art, the aqueous solution full-cycle urea energy-saving production process is simple in process flow, good in operation controllability, low in material consumption, good in heat energy recycling, low in investment cost and little in pollution.

Description

Aqueous solution complete circling urea energy-saving processing technique
Technical field
The present invention relates to urea and produce technology, relate in particular to aqueous solution complete circling urea energy-saving processing technique.
Background technology
Existing urea production process mainly contains traditional aqueous solution recycle to extinction production technique and vaporizing extract process urea production process; The former exist consume high, tail gas is prone to fire and effluent discharge contains problems such as ammonia and urea exceed standard; The latter decomposes the recovery system load when steam stripping efficiency is low increase; Ammonia and carbon dioxide-depleted strengthen, and turndown ratio is poor, operational requirement harsh.And, two kinds of above-mentioned technologies, high pressure synthesis system table of equipment number is many, and system is comparatively complicated, and operation controllability is poor, and heat energy recycle is not good enough, and cost of investment is also higher.
Summary of the invention
The object of the invention is exactly comparatively complicated in order to overcome the system that exists in the existing urea production process, and operation controllability is poor, and heat energy recycle is not good enough; Supplies consumption is high, the more high defective of cost of investment and provide a kind of technical process simple, and operation controllability is good; Supplies consumption is low; Heat energy recycle is good, and cost of investment is low, pollutes few aqueous solution complete circling urea energy-saving processing technique.
The object of the invention can be realized through following technical scheme: aqueous solution complete circling urea energy-saving processing technique comprises following operation:
High pressure synthesis procedure: from the raw materials ammonia in ammonia storehouse, after ammonia pump is pressurized to 20～23MPa, be sent to and be divided into two-way after the liquefied ammonia preheater is heated to 70 ℃, one road and from CO 2The CO of compressor 20～23MPa 2Get into the synthetic tower tower distributor together; Another road gets into through the urea synthesis tower bottom, in tower, accomplishes isothermal high pressure building-up reactions, and reaction product is come out from the top of tower;
The circulation recovery process: the reaction mixture that comes out from synthetic tower successively through press decomposition and absorption and low pressure decomposition and absorption after, urea concentration reaches about 67%, temperature is 140 ℃, sends into vapo(u)rization system then; Urea tail gas is through emptying after the clean ammonia treatment of tail gas of highly effective and safe;
Evaporization process: send into adverse current falling film type preconcentrator from the urea soln that the low pressure recycle system comes, vent one's spleen with middle pressure branch and carry out pre-concentration, urine concentration is brought up to 85% from 67% as thermal source; Make thermal source with expansion steam and steam condensate 85% urine is heated reconcentration, then deliver to urea prilling tower and carry out granulation;
Desorb, hydrolyzing process: ammonium fluid is pumped to the desorb hydrolysis system by desorb, adopts steam heating gas, makes urea and the ammonia content≤5ppm in the sucking water purification of separating that discharges at the bottom of the tower.
Preferably, getting into a road of synthetic tower tower distributor in the said high pressure synthesis procedure is the NH that accounts for total amount 80% 3With 103 ℃ of first ammonium liquid, another road of said entering urea synthesis tower bottom is the NH that accounts for total amount 20% 3
Preferably, the urea synthesizer in the said high pressure synthesis procedure is a liquid phase countercurrent flow formula isothermal synthetic tower.
Preferably, what the clean ammonia treatment of tail gas described in the said circulation recovery process was adopted is horizontal immersion tail gas absorber, and the ammonia content after the processing is less than 1%.
Preferably, middle pressure decomposition and absorption pressure is 1.7MPa described in the said circulation recovery process, and said low pressure decomposition and absorption pressure is 0.3MPa.
Preferably; The heating reconcentration that in the said evaporization process 85% urine is carried out is a two-part heating reconcentration, makes urine concentration bring up to 95% from 85% earlier, accomplishes one section evaporation to urea; The urine that goes out one section vaporizer is passed through two-section evaporating heater again, is concentrated into about 99.6%.
Preferably, come out at the bottom of the desorb hydrolysis tower in said desorb, the hydrolyzing process 188 ℃ separate 160 ℃ the stripping gas classification that sucking water purification, desorb hydrolysis cat head come out and be used in the urea decomposition operation.
Compared with prior art, beneficial effect of the present invention is following:
1, presses decomposition and absorption and low pressure decomposition and absorption in the circulation recovery process in the employing, also can not increase, can not cause the supplies consumption increase even when steam stripping efficiency is low, decompose the recovery system load.
The stripping gas classification that sucking water purification, desorb hydrolysis cat head come out of separating of 2, coming out at the bottom of the desorb hydrolysis tower is used in the urea decomposition operation, is beneficial to and saves steam, keeps systematic water balance.
3, synthetic tower adopts liquid phase countercurrent flow formula isothermal synthetic tower, optimizes building-up reactions, has improved the transformation efficiency of carbonic acid gas, thereby has also improved the production ability of equipment, has reduced the consumption of the load and the material of subsequent handling.
What 4, the clean ammonia treatment of tail gas was adopted is horizontal immersion tail gas absorber, and the ammonia content after the processing has reduced the pollution that exhaust emissions causes atmosphere greatly less than 1%.
Description of drawings
Fig. 1 is an aqueous solution complete circling urea energy-saving processing technique schema of the present invention.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment the present invention is elaborated.
Embodiment:
Aqueous solution complete circling urea energy-saving processing technique as shown in Figure 1, major equipment comprise liquid phase countercurrent flow formula urea synthesizer, urea M.P. absorber, horizontal immersion tail gas absorber, evaporative condenser and desorb water Xie Ta, and its operation is following:
1) high pressure synthesis procedure:
From the raw materials ammonia in ammonia storehouse,, ammonia pump is sent to the liquefied ammonia preheater after being pressurized to 20～23MPa, and be heated to 70 ℃ and be divided into two-way, the one tunnel is about the NH of total amount 80% 3, 103 ℃ of first ammonium liquid and from CO 2The CO of compressor 20～23MPa 2Get into the synthetic tower tower distributor together; The NH on another road about 20% 3Get into through the urea synthesis tower bottom, in tower, accomplish isothermal high pressure building-up reactions, reaction product is come out from the top of tower.
The reaction of industrial production urea is carried out in two steps, and the first step generates intermediate product ammonium carbamate (being called for short the first ammonium) by ammonia and carbon dioxide reaction, and its reaction formula is:
2NH 3(liquid)+CO 2(gas)=NH 4COONH 2(liquid)+Q 1
Second step generated urea by the dehydration of first ammonium, and its reaction formula is:
NH 4COONH 2(liquid)=CO (NH 2) 2(liquid)+H 2O (liquid)-Q 2
The first step reaction is a reversible strong exothermal reaction, and the speed of response that generates ammonium carbamate reaches chemical equilibrium easily than very fast, and reaching carbonic acid gas after the chemical equilibrium, to be converted into the degree of ammonium carbamate very high.The second step reaction is a little thermo-negative reaction of reversible, need in liquid phase, carry out, and speed of response is slow, needs the long period just can reach chemical equilibrium, whole ammonium carbamates is all dewatered be converted into urea even reach chemical equilibrium.
2) circulation recovery process
The reaction mixture that comes out from synthetic tower successively through press decomposition and absorption (pressure 1.7MPa) and low pressure decomposition and absorption (pressure 0.3MPa) after, urea concentration reaches about 67%, temperature is 140 ℃, sends into vapo(u)rization system then; Urea tail gas is through (ammonia content is less than 1%) emptying after the clean ammonia treatment of tail gas of highly effective and safe.
3) evaporization process
Send into adverse current falling film type preconcentrator from the urea soln that the low pressure recycle system comes, vent one's spleen with middle pressure branch and carry out pre-concentration, urine concentration is brought up to 85% from 67% as thermal source; Make thermal source with expansion steam and steam condensate and 85% urine is carried out two sections heating carry out reconcentration, make urine concentration bring up to 95% from 85%, accomplish one section evaporation urea.The urine that goes out one section vaporizer is passed through two-section evaporating heater again, is concentrated into about 99.6%, delivers to urea prilling tower and carries out granulation.
4) desorb, hydrolyzing process
The energy-conservation urea production technology of the aqueous solution recycle to extinction of the foregoing description is fit to newly-built urea plant and existing aqueous solution recycle to extinction device is carried out the energy-saving and production-increase transformation; The retrofit work amount is little; Invest lower; Throughput improves a lot, and can reduce raw materials consumption, elimination environmental pollution significantly, and economic benefit and environmental benefit are remarkable.Aqueous solution complete circling urea manufacturing enterprise carries out the energy-saving and production-increase transformation at home, and wide promotion prospect is arranged.Present about 6,500 ten thousand t/a of China's urea production capacity, wherein 50% is aqueous solution recycle to extinction technology, if the energy-conservation urea production technology of 30% employing aqueous solution recycle to extinction is wherein transformed, year can save energy about 700,000 tce.

Claims (7)

1. aqueous solution complete circling urea energy-saving processing technique is characterized in that, said aqueous solution complete circling urea energy-saving processing technique comprises following operation:
High pressure synthesis procedure: from the raw materials ammonia in ammonia storehouse, after ammonia pump is pressurized to 20～23MPa, be sent to and be divided into two-way after the liquefied ammonia preheater is heated to 70 ℃, one road and from CO 2The CO of compressor 20～23MPa 2Get into the synthetic tower tower distributor together; Another road gets into through the urea synthesis tower bottom, in tower, accomplishes isothermal high pressure building-up reactions, and reaction product is come out from the top of tower;
The circulation recovery process: the reaction mixture that comes out from synthetic tower successively through press decomposition and absorption and low pressure decomposition and absorption after, urea concentration reaches about 67%, temperature is 140 ℃, sends into vapo(u)rization system then; Urea tail gas is through emptying after the clean ammonia treatment of tail gas of highly effective and safe;
Evaporization process: send into adverse current falling film type preconcentrator from the urea soln that the low pressure recycle system comes, vent one's spleen with middle pressure branch and carry out pre-concentration, urine concentration is brought up to 85% from 67% as thermal source; Make thermal source with expansion steam and steam condensate 85% urine is heated reconcentration, then deliver to urea prilling tower and carry out granulation;
Desorb, hydrolyzing process: ammonium fluid is pumped to the desorb hydrolysis system by desorb, adopts steam heating gas, makes urea and the ammonia content≤5ppm in the sucking water purification of separating that discharges at the bottom of the tower.
2. aqueous solution complete circling urea energy-saving processing technique as claimed in claim 1 is characterized in that, getting into a road of synthetic tower tower distributor in the said high pressure synthesis procedure is the NH that accounts for total amount 80% 3With 103 ℃ of first ammonium liquid, another road of said entering urea synthesis tower bottom is the NH that accounts for total amount 20% 3
3. aqueous solution complete circling urea energy-saving processing technique as claimed in claim 2 is characterized in that, the urea synthesizer in the said high pressure synthesis procedure is a liquid phase countercurrent flow formula isothermal synthetic tower.
4. aqueous solution complete circling urea energy-saving processing technique as claimed in claim 1 is characterized in that, what the clean ammonia treatment of tail gas described in the said circulation recovery process was adopted is horizontal immersion tail gas absorber, and the ammonia content after the processing is less than 1%.
5. aqueous solution complete circling urea energy-saving processing technique as claimed in claim 4 is characterized in that, middle pressure decomposition and absorption pressure is 1.7MPa described in the said circulation recovery process, and said low pressure decomposition and absorption pressure is 0.3MPa.
6. aqueous solution complete circling urea energy-saving processing technique as claimed in claim 1; It is characterized in that; The heating reconcentration that in the said evaporization process 85% urine is carried out is a two-part heating reconcentration, makes urine concentration bring up to 95% from 85% earlier, accomplishes one section evaporation to urea; The urine that goes out one section vaporizer is passed through two-section evaporating heater again, is concentrated into about 99.6%.
7. aqueous solution complete circling urea energy-saving processing technique as claimed in claim 1; It is characterized in that, come out at the bottom of the desorb hydrolysis tower in said desorb, the hydrolyzing process 188 ℃ separate 160 ℃ the stripping gas classification that sucking water purification, desorb hydrolysis cat head come out and be used in the urea decomposition operation.
CN2011101561531A 2011-06-10 2011-06-10 Aqueous solution full-cycle urea energy-saving production process Pending CN102816091A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103408467A (en) * 2013-08-08 2013-11-27 中国五环工程有限公司 Low-energy-consumption urea production technology and system adopting CO2 stripping method
CN103435517A (en) * 2013-07-31 2013-12-11 北京众联盛化工工程有限公司 Yield-increasing and energy-saving technology of carbon dioxide stripping urea and equipment of carbon dioxide stripping urea
CN104387296A (en) * 2014-10-28 2015-03-04 河南骏化发展股份有限公司 Production technique of urea
CN104876838A (en) * 2015-06-06 2015-09-02 安徽瀚洋节能科技有限公司 urea production system
CN106117086A (en) * 2016-06-24 2016-11-16 合肥欧克斯新型建材有限公司 A kind of energy-saving increasing on total recycle urea plants production system
CN110997628A (en) * 2017-05-05 2020-04-10 卡萨勒有限公司 Process and plant for the synthesis of urea

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EP1279663A1 (en) * 2001-07-23 2003-01-29 Toyo Engineering Corporation Urea synthesis process
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CN101628883A (en) * 2009-08-10 2010-01-20 四川金圣赛瑞化工有限责任公司 Urea mid pressure decomposing process adopting double heating-falling film countercurrent heat exchange

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103435517A (en) * 2013-07-31 2013-12-11 北京众联盛化工工程有限公司 Yield-increasing and energy-saving technology of carbon dioxide stripping urea and equipment of carbon dioxide stripping urea
CN103435517B (en) * 2013-07-31 2016-03-02 北京众联盛化工工程有限公司 A kind of Increasing Production and Energy Saving method of carbonic acid gas stripping urea and equipment thereof
CN103408467A (en) * 2013-08-08 2013-11-27 中国五环工程有限公司 Low-energy-consumption urea production technology and system adopting CO2 stripping method
CN103408467B (en) * 2013-08-08 2015-02-18 中国五环工程有限公司 Low-energy-consumption urea production technology and system adopting CO2 stripping method
CN104387296A (en) * 2014-10-28 2015-03-04 河南骏化发展股份有限公司 Production technique of urea
CN104387296B (en) * 2014-10-28 2016-09-28 河南骏化发展股份有限公司 A kind of urea production process
CN104876838A (en) * 2015-06-06 2015-09-02 安徽瀚洋节能科技有限公司 urea production system
CN106117086A (en) * 2016-06-24 2016-11-16 合肥欧克斯新型建材有限公司 A kind of energy-saving increasing on total recycle urea plants production system
CN110997628A (en) * 2017-05-05 2020-04-10 卡萨勒有限公司 Process and plant for the synthesis of urea
CN110997628B (en) * 2017-05-05 2022-05-06 卡萨勒有限公司 Process and plant for the synthesis of urea

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Application publication date: 20121212