CN109279625B - Urea hydrolysis ammonia production system and hydrolysis ammonia production method thereof - Google Patents
Urea hydrolysis ammonia production system and hydrolysis ammonia production method thereof Download PDFInfo
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- CN109279625B CN109279625B CN201811467952.9A CN201811467952A CN109279625B CN 109279625 B CN109279625 B CN 109279625B CN 201811467952 A CN201811467952 A CN 201811467952A CN 109279625 B CN109279625 B CN 109279625B
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 199
- 239000004202 carbamide Substances 0.000 title claims abstract description 173
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 171
- 238000006460 hydrolysis reaction Methods 0.000 title claims abstract description 140
- 230000007062 hydrolysis Effects 0.000 title claims abstract description 126
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 88
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 33
- 238000010438 heat treatment Methods 0.000 claims abstract description 62
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 51
- 238000004090 dissolution Methods 0.000 claims abstract description 40
- 238000004891 communication Methods 0.000 claims abstract description 38
- 238000010793 Steam injection (oil industry) Methods 0.000 claims abstract description 14
- 238000003860 storage Methods 0.000 claims abstract description 12
- 239000000243 solution Substances 0.000 claims description 56
- 239000007788 liquid Substances 0.000 claims description 48
- 239000007789 gas Substances 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 16
- 238000010790 dilution Methods 0.000 claims description 8
- 239000012895 dilution Substances 0.000 claims description 8
- 239000002918 waste heat Substances 0.000 claims description 8
- 238000004065 wastewater treatment Methods 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 4
- 230000003301 hydrolyzing effect Effects 0.000 claims 3
- 238000002360 preparation method Methods 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 10
- 238000005265 energy consumption Methods 0.000 abstract description 10
- 239000008187 granular material Substances 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- 239000003546 flue gas Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000003916 acid precipitation Methods 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/02—Preparation, purification or separation of ammonia
- C01C1/08—Preparation of ammonia from nitrogenous organic substances
- C01C1/086—Preparation of ammonia from nitrogenous organic substances from urea
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention discloses a urea hydrolysis ammonia production system. The urea hydrolysis device comprises a urea dissolving/storing tank, wherein the steam flow generated by a steam heating system is divided into two streams, one stream of steam is introduced into a heating coil through a communication pipeline, the heating coil is positioned in a hydrolysis reactor, the other stream of steam is introduced into a stripping steam injection system through the communication pipeline, and the stripping steam injection system is positioned at the bottom of the hydrolysis reactor; the water outlet of the heating coil is communicated with a dissolution heating pipe which is positioned in the urea dissolution/storage tank; a circulating delivery pump and a second electromagnetic control valve are sequentially arranged on a communicating pipeline of the water outlet of the urea dissolving/storing tank to the water inlet; the urea dissolving/storing tank is provided with a communication pipeline leading to the hydrolysis reactor; the upper end of the hydrolysis reactor is communicated with a nozzle, and the nozzle is introduced into an ammonia mixer. The invention has the advantages of low energy consumption, high ammonia conversion rate and low cost. The invention also discloses a hydrolysis ammonia production method of the urea hydrolysis ammonia production system.
Description
Technical Field
The invention relates to the technical field of air pollution control, in particular to an ammonia production system by urea hydrolysis. More specifically, it is a system for ammonia production by urea hydrolysis for flue gas SCR (selective catalytic reduction) denitration. The invention also relates to a hydrolysis ammonia production method of the urea hydrolysis ammonia production system.
Background
The power supply in China is mainly coal-fired thermal power generation, and a large amount of flue gas is generated by the combustion of a boiler of the thermal power plant, wherein NOx is a main pollutant causing photochemical smog and acid rain. In 2012, the requirements of the emission standard of atmospheric pollutants of thermal power plants are formally met, and all fossil fuel combustion boilers must be provided with a denitration device to control the influence of NOx on the environment.
The most commonly used SCR denitration technology is that of goldUnder the action of catalyst, NOx in fume is reduced by ammonia gas to produce N 2 Thereby realizing the standard emission of NOx.
The existing method for preparing ammonia mainly comprises the steps of preparing ammonia by liquid ammonia/ammonia water, preparing ammonia by urea pyrolysis, preparing ammonia by urea hydrolysis and the like. Liquid ammonia/ammonia water all belong to dangerous goods, and there is great risk in transportation and storage. Urea is a colorless chemical, is easy to transport and store, is very suitable for being used as a production raw material of ammonia, but urea pyrolysis ammonia production equipment has the problem of higher operation cost, and urea hydrolysis has the characteristics of low operation energy consumption, safety and stability, and is increasingly popular.
The existing Chinese patent application number is 201710151844.X, the patent name is 'a urea catalytic hydrolysis ammonia production system and method using waste heat', the method adopts hot air as a heat source for ammonia hydrolysis, because the enthalpy value of the hot air is relatively small, the required air quantity is large, and the problems of incomplete hydrolysis and slower hydrolysis process can exist;
the prior Chinese patent application number is 201410490482.3, the patent name is 'method and device for preparing ammonia by utilizing the urea hydrolysis of boiler gas', the boiler flue gas is adopted as a heat source for ammonia hydrolysis, and the flue gas has complex components (fly ash and SO are contained) 2 Etc.), after being introduced into the hydrolysis system, impurities can be generated, the impurities can not be effectively removed, the use of the hydrolysis tank is affected, and the problems of blockage of an ammonia spraying channel, etc. are caused.
The existing urea hydrolysis system is mainly heated by high-quality steam of a power plant, but has the problems of low heat utilization rate, high use cost and the like.
Therefore, development of a urea hydrolysis ammonia production system and a hydrolysis ammonia production method thereof with high heat utilization efficiency, low energy consumption, high ammonia conversion rate and low cost is needed.
Disclosure of Invention
The first object of the invention is to provide an ammonia production system by urea hydrolysis, which has the advantages of higher heat utilization efficiency, low energy consumption, high ammonia conversion rate and low cost, overcomes the defect of low heat utilization efficiency in the prior art, and solves the problems of waste and pollution caused by direct discharge of urea hydrolysis waste liquid.
The second purpose of the invention is to provide a hydrolysis ammonia production method of a urea hydrolysis ammonia production system, which is simple to operate and has high ammonia conversion rate.
In order to achieve the first object of the present invention, the present invention has the following technical solutions: the urea hydrolysis ammonia production system is characterized in that: the system comprises a urea dissolving/storing tank, a hydrolysis reactor and a steam heating system, wherein steam flow generated by the steam heating system is divided into two streams, one stream of steam is introduced into a heating coil pipe through a communication pipeline, the heating coil pipe is positioned in the hydrolysis reactor, the other stream of steam is introduced into a stripping steam injection system through the communication pipeline, and the stripping steam injection system is positioned at the bottom of the hydrolysis reactor;
the water outlet of the heating coil is communicated with a dissolution heating pipe through a communication pipeline, and the dissolution heating pipe is positioned in the urea dissolution/storage tank;
a first communication pipeline communicated with the water inlet is arranged on the water outlet of the urea dissolving/storing tank, and a circulating conveying pump and a second electromagnetic control valve are sequentially arranged on the first communication pipeline;
a water inlet of the hydrolysis reactor is arranged at the lower end of the hydrolysis reactor, and a second communication pipeline communicated with the hydrolysis reactor is arranged on the urea dissolving/storing tank; the second communicating pipeline is sequentially provided with the circulating delivery pump, the first electromagnetic control valve and the energy-saving heat exchanger;
the lower end of the hydrolysis reactor is provided with a hydrolysis reactor liquid outlet which is communicated with the gas-liquid separator through a third communication pipeline, and the third communication pipeline is communicated with the energy-saving heat exchanger;
the upper end of the gas-liquid separator is provided with a gas outlet which is communicated with the ammonia mixer, the lower end of the gas-liquid separator is provided with a gas-liquid separator liquid outlet which is communicated with the urea dissolving/storing tank;
the upper end of the hydrolysis reactor is communicated with a nozzle, and the nozzle is introduced into an ammonia mixer; the dilution fan is communicated with the ammonia mixer through a communication pipeline; and a pipeline leading to a flue denitration system is arranged on the ammonia mixer.
In the above technical scheme, a third electromagnetic control valve is arranged on a communicating pipeline between the gas-liquid separator and the urea dissolving/storing tank.
In the above technical scheme, the water inlet of the urea dissolving/storing tank is arranged above the water outlet.
In the technical scheme, the water outlet of the dissolution heating pipe is communicated with the wastewater treatment system through a communication pipeline.
In the above technical scheme, the vapor flow generated by the vapor heating system is provided with a cooling and pressure reducing device on the communicating pipe of the heating coil.
In order to achieve the second object of the present invention, the present invention has the following technical scheme: the hydrolysis ammonia production method of the urea hydrolysis ammonia production system is characterized by comprising the following steps of: the method comprises the following steps:
s1: urea particles in the urea system and desalted water in the desalted water system are added into a urea dissolving/storing tank through corresponding inlets, and the urea particles are prepared into 40% -60% urea solution;
s2: condensate of a heating coil in the hydrolysis reactor is introduced into a dissolution heating pipe in a urea dissolution/storage tank, urea solution in the urea dissolution/storage tank exchanges heat with the condensate to a temperature of 40 ℃ through the dissolution heating pipe, and water from the dissolution heating pipe enters a wastewater treatment system;
s3: the circulating conveying pump promotes the circulation of urea solution in the pipeline, accelerates the dissolution process, and conveys the dissolved urea solution into the urea hydrolysis system;
s4: the energy-saving heat exchanger on the conveying pipeline raises the temperature of the urea solution on the second communicating pipeline from 40 ℃ to 160-180 ℃;
s5: controlling the hydrolysis reaction in the hydrolysis reactor by a steam heating system, wherein the hydrolysis reaction temperature in the hydrolysis reactor is 150-170 ℃ and the pressure is 1.8-2.1 Mpa;
s6: the stripping steam injection system arranged at the bottom of the hydrolysis reactor takes away the ammonia gas mixture;
s7: the ammonia gas mixture generated in the hydrolysis reactor is discharged out of the hydrolysis reactor through a nozzle, and is sent into an ammonia mixer through the nozzle;
s8: the dilution fan sends air into the ammonia mixer, and the ammonia mixed gas with the ammonia content of 30-35% in the ammonia mixer is diluted to 5% and then sent into the flue denitration system;
s9: the lean urea solution generated after hydrolysis is discharged through a liquid discharge port of the hydrolysis reactor, the temperature of the discharged lean urea solution is 190-210 ℃, the lean urea solution enters a gas-liquid separator after being utilized by waste heat of an energy-saving heat exchanger, the generated gas is converged into an ammonia gas mixer, and the liquid is discharged into a urea dissolving/storing tank through the liquid discharge port of the gas-liquid separator and is used as desalted water.
In the above technical scheme, in S1, urea granules are prepared into a 50% urea solution; in S5, the hydrolysis reaction temperature in the hydrolysis reactor is 160 ℃ and the pressure is 1.9Mpa.
The invention has the following advantages:
(1) The invention has higher heat utilization efficiency, and the energy consumption is 0.9MJ/kg NH 3 Compared with the prior art, the energy consumption of the invention is reduced by 7-10%, the conversion rate of the invention is 99%, the yield of the invention is improved by 5% or more than that of the prior art, the energy consumption of the invention is lower, the ammonia conversion rate is high, and the cost is lower;
(2) The steam heating system is divided into two parts, wherein one steam flow is introduced into the heating coil to indirectly exchange heat with urea solution, and condensate after heat exchange still contains higher temperature and is introduced into the urea dissolving tank to heat the dissolving tank so as to promote the dissolution of urea (the temperature required by urea dissolution is about 40 ℃), so that the energy utilization rate is improved; the other steam flow is taken as stripping steam and is directly sprayed into the urea hydrolysis reactor through a spray head, so that NH in urea solution is accelerated 3 The mixed gas is released to take away NH dissolved in the solution generated by urea hydrolysis 3 And CO 2 Simultaneously, the urea solution is disturbed and stirred, the solution is heated uniformly, so that urea is hydrolyzed more thoroughly, the heat transfer efficiency is high, and the waste heat of stripping steam can also keep the temperature of an ammonia gas mixture conveying pipeline, so that the ammonia gas mixture conveying pipeline is prevented from returningCondensing;
(3) The waste heat of the lean urea solution is used for preheating the urea feed solution, so that the utilization of the waste heat is promoted, the energy-saving effect can be achieved, the lean urea solution (almost pure water and with a certain temperature) after heat exchange and utilization is reused for dissolving urea, and the use of desalted water for dissolving and the heat input are reduced to a certain extent.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention.
In the figure, the device comprises a 1-urea dissolving/storing tank, a 1.1-water inlet, a 1.2-water outlet, a 1.3-first communicating pipeline, a 1.4-second communicating pipeline, a 2-circulating conveying pump, a 3-energy-saving heat exchanger, a 4-hydrolysis reactor, a 4.1-hydrolysis reactor liquid outlet, a 4.2-third communicating pipeline, a 4.3-hydrolysis reactor water inlet, a 5-cooling and depressurizing device, a 6-ammonia mixer, a 7-dilution blower, an 8-gas-liquid separator, an 8.1-gas outlet, an 8.2-gas-liquid separator liquid outlet, a 9-nozzle, a 10-first electromagnetic control valve, an 11-heating coil, a 12-stripping steam injection system, a 13-dissolving heating pipe, a 14-second electromagnetic control valve, a 15-third electromagnetic control valve, a 16-wastewater treatment system, a 17-steam heating system, an 18-desalted water system and a 19-urea system.
Detailed Description
The following detailed description of the invention is, therefore, not to be taken in a limiting sense, but is made merely by way of example. While making the advantages of the present invention clearer and more readily understood by way of illustration.
As can be seen with reference to the accompanying drawings: the urea hydrolysis ammonia production system comprises a urea dissolving/storing tank 1, a hydrolysis reactor 4 and a steam heating system 17, wherein the superheated steam generated by the steam heating system 17 is divided into two streams, one stream is introduced into a heating coil 11 through a communication pipeline, the heating coil 11 is positioned in the hydrolysis reactor 4, the other stream is introduced into a stripping steam injection system 12 through the communication pipeline, the stripping steam injection system 12 is positioned at the bottom of the hydrolysis reactor 4, and the stripping steam injection system 12 can take dissolved NH away 3 And CO 2 The stirring and stirring effects are achieved, so that the solution is heated uniformly, the mixed ammonia gas mixture can be kept warm, and the back coagulation is prevented；
The water outlet of the heating coil 11 is communicated with a dissolution heating pipe 13 through a communication pipeline, and the dissolution heating pipe 13 is positioned in the urea dissolution/storage tank 1; after the heated steam is condensed in the middle of the urea hydrolysis tank, the urea hydrolysis tank still has higher temperature, and is introduced into the urea dissolution tank for heating the dissolution tank, so that the dissolution of urea can be promoted, and the energy utilization rate is improved;
a first communication pipeline 1.3 communicated with the water inlet 1.1 is arranged on the water outlet 1.2 of the urea dissolving/storing tank 1, a circulating conveying pump 2 and a second electromagnetic control valve 14 are sequentially arranged on the first communication pipeline 1.3, the circulating conveying pump 2 can promote the circulation of urea solution in the pipeline, the dissolving process is accelerated, and the dissolved urea solution is conveyed into a urea hydrolysis system;
a water inlet 4.3 of the hydrolysis reactor is arranged at the lower end of the hydrolysis reactor 4, a second communication pipeline 1.4 communicated with the hydrolysis reactor 4 is arranged on the urea dissolving/storing tank 1, and two ends of the second communication pipeline 1.4 are respectively connected with a water outlet 1.2 and the water inlet 4.3 of the hydrolysis reactor; the pipeline is sequentially provided with the circulating delivery pump 2, the first electromagnetic control valve 10 and the energy-saving heat exchanger 3, wherein the energy-saving heat exchanger is used as a urea solution preheating device and exchanges heat with lean urea solution in the second communication pipeline 1.4;
the lower end of the hydrolysis reactor 4 is provided with a hydrolysis reactor liquid discharge outlet 4.1, the hydrolysis reactor liquid discharge outlet 4.1 is communicated with a gas-liquid separator 8 through a third communication pipeline 4.2, the third communication pipeline 4.2 is communicated with the energy-saving heat exchanger 3, and the energy-saving heat exchanger is used as a urea solution preheating device and exchanges heat with lean urea solution;
the upper end of the gas-liquid separator 8 is provided with a gas outlet 8.1, the gas outlet 8.1 is communicated with the ammonia mixer 6, the lower end of the gas-liquid separator is provided with a gas-liquid outlet 8.2, the gas-liquid separator liquid outlet 8.2 is communicated with the urea dissolving/storing tank 1, and liquid is discharged into the urea dissolving tank and is used as desalted water (containing a small amount of urea) for dissolving urea again, so that the use of the desalted water for dissolving and the heat input are reduced to a certain extent;
the upper end of the hydrolysis reactor 4 is communicated with a nozzle 9, and the nozzle 9 is introduced into an ammonia mixer 6; the dilution fan 7 is communicated with the ammonia mixer 6 through a communication pipeline; the ammonia mixer 6 is provided with a pipeline leading to a flue denitration system.
A third electromagnetic control valve 15 is arranged on a communicating pipeline between the gas-liquid separator 8 and the urea dissolving/storing tank 1.
The water inlet 1.1 of the urea dissolving/storing tank 1 is arranged above the water outlet 1.2 of the urea dissolving/storing tank 1, a circulating conveying pump is arranged between the water inlet and the water outlet, the circulating conveying pump can promote circulation of urea solution in a pipeline, the dissolving process is accelerated, and the dissolved urea solution is conveyed into a urea hydrolysis system.
The water outlet of the dissolution heating pipe 13 is communicated with the wastewater treatment system 16 through a communication pipeline.
The vapor flow generated by the vapor heating system 17 is provided with a cooling and pressure reducing device 5 on a communicating pipeline of the heating coil 11, and the temperature and pressure of the vapor flow are adjusted to meet the requirements.
The urea hydrolysis method of the urea hydrolysis ammonia production system comprises the following steps:
s1: the density in the urea system 19 was 1.335kg/m 3 Adding urea granules with density of 1.335kg/m3 into urea dissolving/storing tank 1 through corresponding inlets with desalted water in desalted water system 18 to prepare 40% -60% urea solution;
s2: the heat of the urea dissolving tank is provided by condensate of a hydrolysis reactor coil through a dissolving heating pipe in the urea dissolving/storing tank 1 (the heat exchange temperature is controlled to be 40 ℃), urea is dissolved into endothermic reaction, and the heating can promote the dissolution of urea, and the water discharged from the dissolving heating pipe enters a wastewater treatment system;
s3: the circulating conveying pump 2 can promote the circulation of urea solution in a pipeline, accelerate the dissolution process, and convey the dissolved urea solution into a urea hydrolysis system;
s4: an energy-saving heat exchanger 3 is arranged on the conveying pipeline and is used as a urea solution preheating device to exchange heat with the lean urea solution, and the energy-saving heat exchanger 3 raises the temperature of the urea solution on the second communication pipeline 1.4 from 40 ℃ to about 170 ℃;
s5: the hydrolysis reactor is internally provided with a steam heating system for providing heat for urea hydrolysis, the temperature of the hydrolysis reactor is controlled to be 150-170 ℃ and the pressure is controlled to be 1.8-2.1 Mpa; the steam heating system is a heating coil of the hydrolysis reactor, and the medium in the steam heating system is steam, so that heat is provided for hydrolysis through heat exchange of the coil;
s6: the bottom of the hydrolysis reactor 4 is provided with a stripping steam injection system 12 which can take away dissolved NH 3 And CO 2 The stirring and stirring effects are achieved, so that the solution is heated uniformly, and the mixed ammonia gas mixture can be insulated to prevent back coagulation;
s7: the ammonia gas mixture generated in the hydrolysis reactor 4 is discharged out of the hydrolysis reactor 4 through a nozzle 9, the ammonia gas mixture is sent into an ammonia gas mixer 6 through the nozzle 9, and the pressure of the ammonia gas mixture at the nozzle 9 is reduced from 1.9Mpa to 2.1Mpa to 0.2Mpa to 0.3Mpa;
s8: the dilution fan 7 sends air into the ammonia mixer 6, and the ammonia mixed gas with the ammonia content of 30% -35% in the ammonia mixer 6 is diluted to the ammonia content of 5%, and then sent into the flue denitration system;
s9: the lean urea solution generated after hydrolysis is discharged through a discharge port, and after waste heat utilization is carried out on the lean urea solution at 190-210 ℃ through an energy-saving heat exchanger, the lean urea solution enters a gas-liquid separator 8, the generated gas is converged into an ammonia gas mixer pipeline, and the liquid is discharged into a urea dissolving/storing tank 1 for desalted water (containing a small amount of urea, wherein the content of the liquid urea is less than 0.5 percent, and NH) 3 About 7 ppm).
S1, preparing urea particles into a 50% urea solution; in S5, the hydrolysis reaction temperature in the hydrolysis reactor is 160 ℃ and the pressure is 1.9Mpa.
Example 1
A urea hydrolysis process for preparing an ammonia system from urea comprising the steps of:
s1: the density in the urea system 19 was 1.335kg/m 3 Urea granules of (2) and desalinated water in the desalinated water system 18 respectively by correspondenceIs added to the urea dissolving/storing tank 1, and urea granules are prepared into 40% urea solution;
s2: the condensate of the hydrolysis reactor coil is led into a dissolution heating pipe 13 in the urea dissolution/storage tank 1, the urea solution in the urea dissolution/storage tank 1 exchanges heat with the condensate to 40 ℃ through the dissolution heating pipe 13, and the dissolution heating pipe is discharged into a wastewater treatment system;
s3: the circulating conveying pump 2 promotes the circulation of urea solution in a pipeline, accelerates the dissolution process, and conveys the dissolved urea solution into a urea hydrolysis system;
s4: the energy-saving heat exchanger 3 on the conveying pipeline increases the temperature of the urea solution on the conveying pipeline from 40 ℃ to 170 ℃;
s5: controlling the hydrolysis reaction in the hydrolysis reactor by a steam heating system, wherein the hydrolysis reaction temperature in the hydrolysis reactor is 150 ℃ and the pressure is 1.8Mpa;
s6: the stripping steam injection system 12 arranged at the bottom of the hydrolysis reactor 4 takes away the ammonia gas mixture;
s7: the ammonia gas mixture generated in the hydrolysis reactor 4 is discharged out of the hydrolysis reactor 4 through a nozzle 9, and the ammonia gas mixture is sent into an ammonia gas mixer 6 through the nozzle 9; the pressure of the ammonia gas mixture at the nozzle is reduced from 1.9Mpa to 2.1Mpa to 0.2Mpa to 0.3Mpa;
s8: the dilution fan 7 sends air into the ammonia mixer 6, and the ammonia mixed gas with the ammonia content of 30% -35% in the ammonia mixer 6 is diluted to the ammonia content of 5%, and then sent into the flue denitration system;
s9: the lean urea solution generated after hydrolysis is discharged through a liquid discharge port 4.1 of the hydrolysis reactor, the temperature of the discharged lean urea solution is 190-210 ℃, the lean urea solution enters a gas-liquid separator 8 after being utilized by waste heat of an energy-saving heat exchanger 3, the generated gas is converged into an ammonia mixer 6, and the liquid is discharged into a urea dissolving/storing tank 1 through a liquid discharge port 8.2 of the gas-liquid separator and is used as desalted water.
Conclusion: the energy consumption is 0.9MJ/kgNH 3 (Ammonia) gas, ammonia gas (NH) 3 ) The conversion of (2) was 99.0%.
Example 2
In S1, urea granules are prepared as a 50% urea solution; in S5, the hydrolysis reaction temperature in the hydrolysis reactor is 160 ℃ and the pressure is 1.9Mpa; other method steps are the same as
Example 1.
Conclusion: the energy consumption is 0.9MJ/kgNH 3 The conversion of ammonia was 99.6%.
Example 3
In S1, urea granules are prepared as a 60% urea solution; in S5, the hydrolysis reaction temperature in the hydrolysis reactor is 170 ℃ and the pressure is 2.1Mpa; other method steps are the same as
Example 1.
Conclusion: the energy consumption is 0.9MJ/kgNH 3 The conversion of ammonia was 99.5%.
Other non-illustrated parts are known in the art.
Claims (6)
1. The method for preparing ammonia by urea hydrolysis is characterized in that: the method comprises the steps that an urea hydrolysis ammonia production system is adopted for producing ammonia, the urea hydrolysis ammonia production system comprises a urea dissolution/storage tank (1), a hydrolysis reactor (4) and a steam heating system (17), steam flow generated by the steam heating system (17) is divided into two flows, one flow of steam is led into a heating coil (11) through a communication pipeline, the heating coil (11) is positioned in the hydrolysis reactor (4), the other flow of steam is led into a stripping steam injection system (12) through the communication pipeline, and the stripping steam injection system (12) is positioned at the bottom of the hydrolysis reactor (4);
the water outlet of the heating coil (11) is communicated with a dissolution heating pipe (13) through a communication pipeline, and the dissolution heating pipe (13) is positioned in the urea dissolution/storage tank (1);
a first communication pipeline (1.3) communicated with the water inlet (1.1) is arranged on the water outlet (1.2) of the urea dissolving/storing tank (1), and a circulating conveying pump (2) and a second electromagnetic control valve (14) are sequentially arranged on the first communication pipeline (1.3);
a water inlet (4.3) of the hydrolysis reactor is arranged at the lower end of the hydrolysis reactor (4), and a second communication pipeline (1.4) communicated with the hydrolysis reactor (4) is arranged on the urea dissolving/storing tank (1); the second communication pipeline (1.4) is sequentially provided with the circulating delivery pump (2), the first electromagnetic control valve (10) and the energy-saving heat exchanger (3);
the lower end of the hydrolysis reactor (4) is provided with a hydrolysis reactor liquid outlet (4.1), the hydrolysis reactor liquid outlet (4.1) is communicated with a gas-liquid separator (8) through a third communication pipeline (4.2), and the third communication pipeline (4.2) is communicated with the energy-saving heat exchanger (3);
the upper end of the gas-liquid separator (8) is provided with a gas outlet (8.1), the gas outlet (8.1) is communicated with the ammonia mixer (6), the lower end of the gas-liquid separator is provided with a gas outlet (8.2), and the gas-liquid separator liquid outlet (8.2) is communicated with the urea dissolving/storing tank (1);
the upper end of the hydrolysis reactor (4) is communicated with a nozzle (9), and the nozzle (9) is communicated with an ammonia mixer (6); the dilution fan (7) is communicated with the ammonia mixer (6) through a communication pipeline; the ammonia mixer (6) is provided with a pipeline leading to a flue denitration system;
the hydrolysis ammonia production method of the urea hydrolysis ammonia production system comprises the following steps:
s1: urea particles in the urea system (19) and desalted water in the desalted water system (18) are added into the urea dissolving/storing tank (1) through corresponding inlets, and the urea particles are configured into 40% -60% urea solution;
s2: the condensate of the heating coil in the hydrolysis reactor (4) is led into a dissolution heating pipe (13) in the urea dissolution/storage tank (1), the urea solution in the urea dissolution/storage tank (1) exchanges heat with the condensate to 40 ℃ through the dissolution heating pipe (13), and the dissolution heating pipe (13) outputs water into the wastewater treatment system;
s3: the circulating conveying pump (2) promotes the circulation of urea solution in the pipeline, accelerates the dissolution process, and conveys the dissolved urea solution into the urea hydrolysis system;
s4: the energy-saving heat exchanger (3) on the conveying pipeline raises the temperature of the urea solution on the second communication pipeline (1.4) from 40 ℃ to 160-180 ℃;
s5: the hydrolysis reaction in the hydrolysis reactor (4) is controlled by a steam heating system (17), the hydrolysis reaction temperature in the hydrolysis reactor is 150-170 ℃ and the pressure is 1.8-2.1 Mpa;
s6: a stripping steam injection system (12) arranged at the bottom of the hydrolysis reactor (4) takes away the ammonia gas mixture;
s7: the ammonia gas mixture generated in the hydrolysis reactor (4) is discharged out of the hydrolysis reactor (4) through a nozzle (9), and the ammonia gas mixture is sent into an ammonia gas mixer (6) through the nozzle (9);
s8: the dilution fan (7) sends air into the ammonia mixer (6), and the ammonia mixed gas with the ammonia content of 30% -35% in the ammonia mixer (6) is diluted to the ammonia content of 5%, and then sent into the flue denitration system;
s9: the lean urea solution generated after hydrolysis is discharged through a liquid discharge outlet (4.1) of the hydrolysis reactor, the temperature of the discharged lean urea solution is 190-210 ℃, the lean urea solution enters a gas-liquid separator (8) after being utilized by waste heat of an energy-saving heat exchanger (3), the generated gas is converged into an ammonia mixer (6), and the liquid is discharged into a urea dissolving/storing tank (1) through a liquid discharge outlet (8.2) of the gas-liquid separator and is used as desalted water.
2. The method for producing ammonia by hydrolyzing urea according to claim 1, wherein: and a third electromagnetic control valve (15) is arranged on a communicating pipeline between the gas-liquid separator (8) and the urea dissolving/storing tank (1).
3. The urea hydrolysis ammonia production method according to claim 1 or 2, characterized in that: the water inlet (1.1) of the urea dissolving/storing tank (1) is arranged above the water outlet (1.2).
4. A process for the preparation of ammonia by hydrolysis of urea according to claim 3, characterized in that: the water outlet of the dissolution heating pipe (13) is communicated with the wastewater treatment system (16) through a communication pipeline.
5. The method for producing ammonia by hydrolyzing urea according to claim 4, wherein: the steam flow generated by the steam heating system (17) is provided with a cooling and pressure reducing device (5) on a communicating pipe of the heating coil (11).
6. The method for producing ammonia by hydrolyzing urea according to claim 5, wherein: s1, preparing urea particles into a 50% urea solution; in S5, the hydrolysis reaction temperature in the hydrolysis reactor (4) is 160 ℃ and the pressure is 1.9Mpa.
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| CN111036076A (en) * | 2019-12-26 | 2020-04-21 | 内蒙古电力(集团)有限责任公司内蒙古电力科学研究院分公司 | Urea hydrolysis ammonia supply system with injection steam as heat source |
| CN110963506B (en) * | 2019-12-26 | 2021-04-06 | 内蒙古电力(集团)有限责任公司内蒙古电力科学研究院分公司 | Urea ammonia production system with injection steam as auxiliary heat source |
| CN112010328A (en) * | 2020-09-14 | 2020-12-01 | 中国华电科工集团有限公司 | Urea hydrolysis ammonia production equipment |
| CN112691561A (en) * | 2020-12-22 | 2021-04-23 | 青岛诺瑞尔节能环保科技有限公司 | Gas-liquid mixer for denitration and use method thereof |
| CN112499649A (en) * | 2020-12-24 | 2021-03-16 | 昆山市三维换热器有限公司 | Urea hydrolysis ammonia dehydration system and method thereof |
| CN113274855B (en) * | 2021-04-13 | 2022-06-07 | 华电电力科学研究院有限公司 | System and method for preparing denitration urea solution by using flue gas waste heat of gas-steam combined cycle unit |
| CN113697827B (en) * | 2021-08-20 | 2023-05-16 | 江西赣能股份有限公司 | SCR denitration urea hydrolysis ammonia production device |
| CN114436291B (en) * | 2022-02-16 | 2023-11-10 | 西安西热锅炉环保工程有限公司 | Heat supply system and method for preparing ammonia through urea hydrolysis reaction |
| CN114291824A (en) * | 2022-02-16 | 2022-04-08 | 西安西热锅炉环保工程有限公司 | Flexible heat supply system and method for preparing ammonia through urea hydrolysis reaction |
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