CN109319736B - Ammonia tank purge gas recovery device and process thereof - Google Patents
Ammonia tank purge gas recovery device and process thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
- C01B3/52—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with liquids; Regeneration of used liquids
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- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/02—Preparation, purification or separation of ammonia
- C01C1/022—Preparation of aqueous ammonia solutions, i.e. ammonia water
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/02—Preparation, purification or separation of ammonia
- C01C1/12—Separation of ammonia from gases and vapours
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
- C01B2203/0405—Purification by membrane separation
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Abstract
The invention belongs to the technical field of purified ammonia absorption and hydrogen recovery, and particularly relates to an ammonia absorption device for purge gas of an ammonia tank for synthetic ammonia and a hydrogen recovery process. The hydrogen recovery process in the process adopts a hollow fiber membrane to separate pure hydrogen needed by devices for synthesizing ammonia, hydrogen peroxide and the like, the ammonia content after purification is controlled to be less than 50ppm, the purge gas is heated to 50 ℃ and enters the hollow fiber membrane to separate the hydrogen, and the whole membrane separation system is basically free of moving parts, has the characteristics of few control loops and monitoring points, convenient and quick start and stop, few maintenance and extremely high start rate. The concentrated ammonia water can be recovered to obtain pure liquid ammonia by further treatment, the membrane tail gas mainly contains methane and nitrogen, etc., and is fed into primary converter for synthetic ammonia as fuel to provide heat source for equipment, and the discharged gas after combustion is mainly H2O and CO2And no pollution to the atmosphere.
Description
Technical Field
The invention belongs to the technical field of purified ammonia absorption and hydrogen recovery, and particularly relates to an ammonia absorption device for purge gas of an ammonia tank for synthetic ammonia and a hydrogen recovery process.
Background
At present, in the production process of a domestic and overseas synthetic ammonia device, liquid ammonia produced by the synthetic ammonia device enters an ammonia tank for storing liquid ammonia, non-condensable gas dissolved in the liquid ammonia is flashed out due to decompression flash evaporation, and simultaneously flash evaporation gas is formed and a certain amount of purge gas generated in the liquid ammonia enters the ammonia tank due to leakage and the like. In order to maintain the pressure of the liquid ammonia storage tank at a certain level, the part of flash gas is discharged, thereby forming purge gas of the ammonia tank; typically, the ammonia tank purge gas contains 40% gaseous ammonia, 38% hydrogen, and 8% methane and 14% nitrogen, with the total flow rate varying depending on the ammonia synthesis scale, and the pressure varying with the ammonia tank control pressure. The pressure tank purge gas is referred to herein and is typically at a purge gas pressure of 2.1 MPaG.
Ammonia is a typical toxic and harmful industrial pollutant, and if a large amount of ammonia-containing purge gas is not recycled and directly discharged into the atmosphere, the ammonia and hydrogen loss is caused, the economic benefit of enterprises is directly reduced, the living environment of people is polluted, and in addition, the ammonia can also cause harm to the health of human bodies; if the exhausted gas of the ammonia tank is directly sent into a first-stage furnace for direct combustion as fuel after recovery, NOx gas is generated after ammonia combustion, the NOx in flue gas exceeds the standard to form acid rain, underground water is polluted, the environment is polluted, and the emission does not reach the standard; if the ammonia tank purge gas is directly sent into the normal pressure neutralization of the ammonium nitrate device after being decompressed for recovery, only the ammonia gas in the ammonia tank purge gas is absorbed in the normal pressure neutralization, and other valuable gases such as methane, hydrogen and the like in the purge gas cannot be recovered, so that a great deal of waste of useful gas is caused, and the economic benefit of enterprises is reduced.
With the rapid development of the synthetic ammonia industry in China, the yield of synthetic ammonia is continuously increased, and the discharged purge gas is further increased, so that ammonia and hydrogen in the purge gas of an ammonia tank can be separated and recycled, and the discharge of the purge gas is pollution-free, and the new technology becomes a new technology which is needed at present; the ammonia purification tower of the ammonia recovery device in the common purge gas recovery device is generally divided into an upper section and a lower section for absorption, a bubble cap, a vertical tower plate or a float valve is adopted in the ammonia purification tower as a mass transfer element, and the lower section is a bubble layer, so that the defects that the tower diameter of the ammonia purification tower is large, gas-liquid contact is poor, excessive desalted water is needed to remove ammonia in purge gas of an ammonia tank, a large amount of desalted water with high price is wasted, a large amount of low-concentration dilute ammonia water can be generated, the concentration of the recovered dilute ammonia water is low, and the cost of ammonia recovery by steam stripping evaporation is greatly improved; at present, the main technology for recovering hydrogen in the purge gas of the ammonia tank comprises a hollow fiber membrane method, a low-temperature freezing method, a pressure swing adsorption method and the like.
Although the chinese patent application CN 103864098A discloses an ammonia absorption device and an absorption process for ammonia tank purge gas, an ammonia purification tower is used as a main device, an ammonia evaporation cooling system is matched at the lower part of the tower, a compressor is used to compress evaporated ammonia gas, and high-pressure ammonia gas is cooled by evaporation cooling, so that the ammonia gas is changed from gaseous state to liquid state, and a circulation cooling process is completed; the upper part of the tower is subjected to countercurrent absorption reaction with desalted water by using a plurality of layers of tower plates, but the effect of ammonia removal is not ideal, the ammonia content of the washed purge gas is 150-200 ppm, and the hydrogen in the purge gas is not separated, recycled and reused, but is directly used as fuel to be combusted, so that the method is not very favorable for environment and improving the economic benefit of enterprises.
Disclosure of Invention
The invention aims to provide a process for recovering purge gas of an ammonia tank, which has the advantages of simple process flow, easy operation, small equipment size, no desalted water waste and high ammonia recovery rate, and overcomes the technical defects of the prior process device. The hydrogen recovery process in the process adopts a hollow fiber membrane to separate pure hydrogen needed by devices for synthesizing ammonia, hydrogen peroxide and the like, the ammonia content after purification is controlled to be less than 50ppm, the purge gas is heated to 50 ℃ and enters the hollow fiber membrane to separate the hydrogen, the whole membrane separation system is basically free of moving parts, control loops and monitoring points are few, the start and stop are convenient and quick, the maintenance is few, and the start rate is extremely high.
In order to achieve the above purpose, the specific technical solution of the present application is:
the ammonia tank purge gas recovery device comprises a bubble absorber, an absorption liquid pump a, an absorption liquid pump b, a desalination water tank, an absorption tower, a circulating washing tower, a circulating absorption pump a, a circulating absorption pump b, a demister, a heater, a membrane module and a hydrogen compressor, wherein a storage liquid ammonia tank is connected with the bubble absorber through a purge gas inlet area pipeline, the circulating washing tower is connected with the bubble absorber through a circulating washing tower kettle liquid level control valve, a desalination water tank enters the desalination water tank through a desalination water tank liquid level control valve, and is connected with the absorption tower through the absorption liquid pump a and the absorption liquid pump b; the bubbling absorber is connected with a gas phase pipe orifice at the lower part of the circulating washing tower through a pipeline, the outlets of the circulating absorption pump a and the circulating absorption pump b are divided into two paths, one path is connected with the circulating washing tower through a tower top inlet pipeline of the circulating washing tower, and the other path is connected with the bubbling absorber through a circulating washing tower kettle liquid level control valve; the circulating washing tower is connected with a gas phase pipeline inlet at the lower part of the absorption tower through a pipeline, an absorption liquid pump a and an absorption liquid pump b are connected with the absorption tower, and the absorption tower is connected with the circulating washing tower through a liquid phase pipeline; the absorption tower is connected with a demister through a pipeline, the absorption tower is connected with a urea device through a demister liquid level control valve and a bubbling absorber liquid level control valve, the demister is connected with a heater and then connected with a membrane assembly through a purge gas temperature control regulating valve, and the membrane assembly is respectively connected with a hydrogen compressor and a membrane tail gas delivery pipeline.
The ammonia tank purge gas recovery process comprises the following steps: the ammonia in the ammonia tank purge gas is dissolved into water to form concentrated ammonia water (> 20%) through a set of ammonia purification system, so that the ammonia content in the purge gas is reduced to <50ppm, water vapor droplets possibly carried in the purge gas are removed through separation, the purge gas enters a membrane separation system, and hydrogen in the purge gas is separated through a hollow fiber membrane, wherein the recovery rate of the hydrogen is greater than 90% and the purity is greater than 92%. The remaining tail gas can be used as fuel to be sent to the relevant production unit.
The specific process is as follows:
the first step is as follows: after the purge gas from the ammonia tank is buffered by a buffer tank (the pressure is 2.0-2.1 MPa), the purge gas flow entering the system is stabilized by a flow regulating valve, then enters the bottom of the bubbling absorber through a collecting pipe, and is subjected to countercurrent bubbling absorption in the bubbling absorber together with the dilute ammonia water (or dilute ammonia water from other ammonia washing devices) collected by the circulating washing tower. The bubbling absorber is a shell-and-tube reaction absorber, the absorption reaction of ammonia and dilute ammonia water is carried out in the shell pass, and the reaction of ammonia and desalted water is an exothermic reaction, so that the temperature of the ammonia water is prevented from rising, and the tube pass of the bubbling absorber is cooled by circulating water, thereby accelerating the dissolution of the ammonia in the desalted water. Most of ammonia in the purge gas is absorbed by ammonia water after passing through the bubbling absorber, and 20-30% of concentrated ammonia water generated by absorption is sent to a relevant device after the liquid level of the bubbling absorber is controlled by a liquid level regulating valve for ammonia recovery treatment. After most of ammonia is absorbed by the purge gas of the ammonia tank through a bubbling absorber, the purge gas enters a circulating washing tower at the temperature of 40-45 ℃.
The second step is that: the purge gas washed by the bubbling absorber enters the lower part of a circulating washing tower, enters a spray head at the top of the circulating washing tower to be sprayed with dilute ammonia water from a circulating absorption pump a/b, and is in countercurrent contact with a regular packing section of the tower, so that the gas ammonia in the purge gas from the bubbling absorber is further absorbed, the ammonia content in the purge gas is reduced, the ammonia content can be reduced to a micro-scale level, and the purge gas leaves the circulating washing tower and enters the absorption tower; the outlet of the circulating absorption pump a/b is divided into two paths, one path enters a top spray head of the circulating absorption tower to absorb the gas ammonia in the purge gas, and the other path enters a bubble absorber after the liquid level of the circulating washing tower is controlled by a regulating valve, supplements the liquid level of the bubble absorber and absorbs the ammonia in the purge gas. Because the ammonia content in the section is less and the reaction heat release of the generated ammonia water is not high, a cooling device is arranged at the end of the section.
The third step: the purge gas from the top of the circulating washing tower enters the lower part of the absorption tower, the absorption tower is in a form of a float valve tower, the purge gas passes through all layers of tower trays step by step and is in countercurrent contact with desalted water from the top to the bottom for absorption, desalted water from an absorption liquid pump is added on the uppermost float valve tower tray of the tower and flows downwards step by step, the purge gas rises step by step and is in mass transfer reaction with desalted water with lower and lower concentration, so that the ammonia content of the purge gas is continuously reduced, the ammonia content of the purge gas out of the absorption tower is less than 50ppm, and the temperature is about 35-40 ℃; and (4) conveying the bottom kettle liquid of the absorption tower to a circulating washing tower for further thickening.
The fourth step: the ammonia tank purge gas after ammonia purification through a bubbling absorber and a double tower enters a demister (X-101) at the pressure of 1.8MPa and the temperature of 35-40 ℃ and the ammonia content of less than 50ppm, most of fog drops and other particles are removed, in order to prevent water vapor in the purge gas from being condensed into liquid drops in the subsequent process, gas from the demister enters a heater (E-101), the purge gas is heated to 50 ℃ by steam, the raw gas is far away from the dew point and the operating temperature of a membrane separation system is constant, and a steam regulating valve (TV-101) and a temperature transmitter (TT-101) are combined to realize the regulation, indication, alarm and interlocking of the temperature of the raw gas; the heated gas enters a hollow low-pressure membrane separator group for separation to obtain hydrogen with the pressure of more than 0.5MPaG, the hydrogen is sent to a synthetic ammonia system for producing synthetic ammonia after being pressurized, and non-permeable gas (mainly methane, nitrogen and hydrogen) is sent to a first-stage furnace for burning as fuel after being depressurized. The hydrogen recovery was >90% and the purity was > 90%.
Compared with the traditional purge gas recovery process, the positive effects of the invention are as follows:
in the device, the temperature of purge gas can be well reduced by arranging a circulating water cooling device of the bubble absorber, so that the temperature of the mixture of the purge gas and ammonia water in the bubble absorber is reduced, and the dissolving recovery rate of ammonia is greatly improved; most of ammonia is absorbed by a bubbling absorber, the purge gas absorbed by bubbling adopts a double-tower ammonia absorption and purification process, a circulating tower adopts large circulation absorption, so that the ammonia in the purge gas can be further greatly reduced, excessive desalted water is not added, the concentration of dilute ammonia water is improved, and the absorption tower adopts a fixed tower disc type absorber, and fresh desalted water is in countercurrent contact with the purge gas for gradual absorption, so that the ammonia content of the purge gas finally discharged out of the tower is ensured to be less than 50 ppm.
And (II) performing membrane separation on the washed purge gas through a hollow fiber membrane, recovering hydrogen and returning the hydrogen to a production system, and sending the non-permeate gas to a first-stage furnace to be used as fuel.
Thirdly, the method produces the stronger ammonia water (20-30%), thereby reducing the energy consumption of the subsequent ammonia distillation process; the membrane permeation separation recovery process is adopted to recover the hydrogen to return to a production system for use, and the production cost of enterprises is reduced, so that the method is a production technology with low cost, high efficiency, energy consumption saving and high added value.
Description of the drawings:
FIG. 1 is a schematic structural view of an ammonia tank purge gas recovery apparatus according to the present invention.
Wherein: 1-a bubble absorber, 2-an absorption liquid pump a, 2 ' -an absorption liquid pump b, 3-a desalted water tank, 4-a desalted water tank liquid level control valve, 5-an absorption tower, 6-a bubble absorber to circulating washing tower gas phase pipeline, 7-a circulating washing tower to absorption tower gas phase pipeline, 8-an absorption tower to circulating washing tower liquid phase pipeline, 9-a circulating washing tower, 10-a circulating absorption pump a outlet to circulating washing tower top inlet pipeline, 10 ' -a circulating absorption pump b outlet to circulating washing tower top inlet pipeline, 11-a circulating absorption pump a, 11 ' -a circulating absorption pump b, 12-a circulating washing tower kettle liquid level control valve, 13-a bubble absorber liquid level control valve, 14-ammonia tank purge gas inlet area pipeline, 15-an absorption tower to demister gas phase pipeline, 16-a demister liquid level control valve, 17-a demister, 18-a heater, 19-a purge gas temperature control regulating valve, 20-a membrane assembly, 21-a membrane tail gas outward delivery pipeline and 22-a hydrogen compressor.
Detailed Description
The ammonia tank purge gas recovery device comprises a bubble absorber, an absorption liquid pump a, an absorption liquid pump b, a desalination water tank, an absorption tower, a circulating washing tower, a circulating absorption pump a, a circulating absorption pump b, a demister, a heater, a membrane module and a hydrogen compressor, wherein a storage liquid ammonia tank is connected with the bubble absorber through a purge gas inlet area pipeline, the circulating washing tower is connected with the bubble absorber through a circulating washing tower kettle liquid level control valve, a desalination water tank enters the desalination water tank through a desalination water tank liquid level control valve, and is connected with the absorption tower through the absorption liquid pump a and the absorption liquid pump b; the bubbling absorber is connected with a gas phase pipe orifice at the lower part of the circulating washing tower through a pipeline, the outlets of the circulating absorption pump a and the circulating absorption pump b are divided into two paths, one path is connected with the circulating washing tower through a tower top inlet pipeline of the circulating washing tower, and the other path is connected with the bubbling absorber through a circulating washing tower kettle liquid level control valve; the circulating washing tower is connected with a gas phase pipeline inlet at the lower part of the absorption tower through a pipeline, an absorption liquid pump a and an absorption liquid pump b are connected with the absorption tower, and the absorption tower is connected with the circulating washing tower through a liquid phase pipeline; the absorption tower is connected with a demister through a pipeline, the absorption tower is connected with a urea device through a demister liquid level control valve and a bubbling absorber liquid level control valve, the demister is connected with a heater and then connected with a membrane assembly through a purge gas temperature control regulating valve, and the membrane assembly is respectively connected with a hydrogen compressor and a membrane tail gas delivery pipeline.
In order that the present disclosure may be more readily understood, reference will now be made to the following description taken in conjunction with the accompanying drawings. It should not be understood that the scope of the above-described subject matter of the present invention is limited to the following examples.
All references to% in this application, unless otherwise indicated, refer to their volume percent, i.e.,% vol.
Example 1:
the ammonia tank purge gas recovery device in the specific implementation mode is adopted to carry out the ammonia tank purge gas recovery process, and the ammonia tank purge gas recovery device comprises the following steps:
the first step is as follows: the purge gas of ammonia tank for storing liquid ammonia contains 40% of gas ammonia and 38% of hydrogenGas, 8% methane and 14% nitrogen, total flow 3000Nm3H; the purge gas of the ammonia tank enters a bubble absorber through a purge gas inlet area pipeline, and reacts with dilute ammonia water from a circulating washing tower kettle liquid level control valve in the bubble absorber to generate 20-30% concentrated ammonia water, and the concentrated ammonia water is cooled by circulating water of a shell pass, so that the ammonia recovery rate is increased.
Desalted water from outside the boundary area enters the desalting water tank through a desalting water tank level control valve and then is pumped into the absorption tower through an absorption liquid pump a/b to remove ammonia gas in the purge gas, and the stroke of the absorption liquid pump a/b is controlled to ensure that the ammonia content in the purge gas is less than 50 ppm.
The second step is that: the gas ammonia discharged from the gas phase pipeline of the bubble absorber to the circulating washing tower is removed; the outlet of the circulating absorption pump a/b is divided into two paths, one path of the outlet of the circulating absorption pump a/b enters the circulating washing tower from the inlet pipeline at the top of the circulating washing tower, and the other path of the outlet of the circulating absorption pump a/b enters the bubbling absorber after passing through the liquid level control valve of the tower of the circulating washing tower.
The third step: circulating the washing tower to a gas phase pipeline of the absorption tower to enter an inlet of a gas phase pipeline at the lower part of the absorption tower, and carrying out countercurrent contact on tower trays of the absorption tower and desalted water from an absorption liquid pump a/b to remove most of ammonia in exhausted gas, wherein the ammonia content of a demister is controlled to be less than 50ppm, and the temperature is controlled to be 35-40 ℃; tower bottom liquid of the absorption tower enters the circulating washing tower through a liquid phase pipeline.
The fourth step: the gassing of speeding of absorption tower gets into the defroster through absorption tower to defroster gas phase pipeline, separates the liquid drop of speeding the gassing, and the regulation back of the thin aqueous ammonia process defroster liquid level control valve after the separation, the thick aqueous ammonia of thin aqueous ammonia and tympanic bulla absorber liquid level control valve mixes, goes the urea device to recycle after mixing, and the gassing of speeding after the defroster separation gets into the heater.
The fifth step: the purge gas separated from the demister is heated in a heater and is regulated by a purge gas temperature control regulating valve, the purge gas enters a membrane module after the temperature control is qualified, useful hydrogen is recovered, the hydrogen enters a hydrogen compressor to be pressurized to 2.5map and then is supplemented to a front working section for recycling, and membrane tail gas is conveyed to a first-stage furnace through an outward pipeline for combustion.
The ammonia tank purge gas treatment is carried out by adopting the process, about 7400 tons of ammonia can be recovered each year, about 8208000 standard prescriptions of hydrogen can be recovered, if all the ammonia is returned to a synthetic ammonia system for producing synthetic ammonia, about 4100 tons of synthetic ammonia can be increased, and about 11500 tons of synthetic ammonia can be recovered in total, so that the process has great economic value.
Although the present invention has been described in detail with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
Claims (3)
1. Ammonia tank purge gas recovery unit, including tympanic bulla absorber (1), absorption liquid pump a (2), absorption liquid pump b (2 '), desalination basin (3), absorption tower (5), circulation scrubbing tower (9), circulation absorption pump a (11), circulation absorption pump b (11'), defroster (17), heater (18), membrane module (20) and hydrogen compressor (22), its characterized in that: the ammonia storage tank is connected with the bubble absorber (1) through a purge gas inlet area pipeline (14), the circulating washing tower (9) is connected with the bubble absorber (1) through a circulating washing tower kettle liquid level control valve (12), the desalted water tank enters the desalting water tank (3) through a desalting water tank liquid level control valve (4), and is connected with the absorption tower (5) through an absorption liquid pump a (2) and an absorption liquid pump b (2'); the bubbling absorber (1) is connected with a gas phase pipe orifice at the lower part of the circulating washing tower (9) through a pipeline, the outlets of the circulating absorption pump a (11) and the circulating absorption pump b (11') are divided into two paths, one path is connected with the circulating washing tower (9) through a tower top inlet pipeline (10) of the circulating washing tower, and the other path is connected with the bubbling absorber (1) through a circulating washing tower kettle liquid level control valve (12); the circulating washing tower (9) is connected with the inlet of a gas phase pipeline at the lower part of the absorption tower (5) through a pipeline, an absorption liquid pump a (2) and an absorption liquid pump b (2') are connected with the absorption tower (5), and the absorption tower (5) is connected with the circulating washing tower (9) through a liquid phase pipeline (8); the absorption tower (5) is connected with a demister (17) through a pipeline, and then is connected with a urea device through a demister liquid level control valve (16) and a bubbling absorber liquid level control valve (13), the demister (17) is connected with a heater (18) and then is connected with a membrane module (20) through a purge gas temperature control regulating valve (19), and the membrane module (20) is respectively connected with a hydrogen compressor (22) and a membrane tail gas outward conveying pipeline (21).
2. The ammonia tank purge gas recovery process is characterized by comprising the following specific steps of:
the first step is as follows: after the purge gas from the ammonia tank is buffered by the buffer tank, the flow of the purge gas is stabilized into the system by the flow regulating valve, and then enters the bottom of the bubbling absorber by the collecting pipe, and is subjected to countercurrent bubbling absorption in the bubbling absorber together with the dilute ammonia water extracted by the circulating washing tower or the dilute ammonia water from other ammonia washing devices; cooling the tube pass of the bubbling absorber by using circulating water; most of ammonia in the purge gas is absorbed by ammonia water after passing through the bubbling absorber, and 20-30% of concentrated ammonia water generated by absorption is sent into an ammonia recovery processing device after the liquid level of the bubbling absorber is controlled by a liquid level regulating valve; after most of ammonia is absorbed by purge gas of an ammonia tank through a bubbling absorber, controlling the temperature to be 40-45 ℃ and then entering a circulating washing tower;
the second step is that: the purge gas washed by the bubbling absorber enters the lower part of a circulating washing tower, enters a spray head at the top of the circulating washing tower to be sprayed with dilute ammonia water from a circulating absorption pump a/b, and is in countercurrent contact with a regular packing section of the tower, so that the gas ammonia in the purge gas from the bubbling absorber is further absorbed, the ammonia content in the purge gas is reduced, the ammonia content is reduced to a micro-scale level, and the purge gas leaves the circulating washing tower and enters the absorption tower; the outlet of the circulating absorption pump a/b is divided into two paths, one path enters a top spray head of the circulating absorption tower to absorb the gas ammonia in the purge gas, and the other path enters a bubble absorber after the liquid level of the circulating washing tower is controlled by a regulating valve, supplements the liquid level of the bubble absorber and absorbs the ammonia in the purge gas;
the third step: the purge gas from the top of the circulating washing tower enters the lower part of the absorption tower, the absorption tower is in a form of a float valve tower, the purge gas passes through all layers of tower trays step by step and is in countercurrent contact with desalted water from the top to the bottom for absorption, desalted water from an absorption liquid pump is added on the uppermost stage of the tower tray and flows downwards step by step, the purge gas rises step by step and is in mass transfer reaction with desalted water with lower and lower concentration, so that the ammonia content of the purge gas is continuously reduced, the ammonia content of the purge gas out of the absorption tower is less than 50ppm, and the temperature is 35-40 ℃; the bottom kettle liquid of the absorption tower is sent to a circulating washing tower for further thickening;
the fourth step: the ammonia tank purge gas after passing through the bubbling absorber and the double-tower ammonia purification enters a demister under the pressure of 1.8MPa and the temperature of 35-40 ℃ and the ammonia content of less than 50ppm, the gas from the demister enters a heater, the purge gas is heated to 50 ℃ by steam, the raw material gas is far away from the dew point and the operating temperature of a membrane separation system is constant, and a steam regulating valve and a temperature transmitter are combined to realize the regulation, indication, alarm and interlocking of the raw material gas temperature; the heated gas enters a hollow low-pressure membrane separator group for separation to obtain hydrogen with the pressure of more than 0.5MPaG, the hydrogen is sent to a synthetic ammonia system for producing synthetic ammonia after being pressurized, and the non-permeation gas is sent to a first-stage furnace for burning as fuel after being decompressed.
3. The ammonia tank purge gas recovery process of claim 2, wherein: the bubbling absorber is a shell-and-tube reaction absorber, and the absorption reaction of ammonia and dilute ammonia water is carried out in a shell pass.
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| CN112279216A (en) * | 2020-11-16 | 2021-01-29 | 河南骏化发展股份有限公司 | Device and process for preparing hydrogen for fuel cell by using synthetic ammonia purge gas |
| CN112279271A (en) * | 2020-11-16 | 2021-01-29 | 河南骏化发展股份有限公司 | Device and process for producing electronic-grade ammonia water by using purge gas of synthetic ammonia |
| CN116282071A (en) * | 2023-02-28 | 2023-06-23 | 新疆玉象胡杨化工有限公司 | Comprehensive recovery process for purge gas and special device thereof |
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| CN102515099A (en) * | 2011-12-07 | 2012-06-27 | 天邦膜技术国家工程研究中心有限责任公司 | Membrane separation method and device for recycling hydrogen from purge gas of synthetic ammonia liquid ammonia storage tank |
| CN202876637U (en) * | 2012-08-01 | 2013-04-17 | 天邦膜技术国家工程研究中心有限责任公司 | Double-tower ammonia washing system for membrane separation treatment |
| CN203959842U (en) * | 2014-07-02 | 2014-11-26 | 安徽泉盛化工有限公司 | Reclaim the speed system of ammonia in venting of ammonia car |
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