CN102218261B - Method and equipment for collecting carbon dioxide from fuel gas by using ammonia water fine spraying - Google Patents

Abstract

The invention provides a method for collecting carbon dioxide from fuel gas by using ammonia water fine spraying. The method comprises the following steps that: step A, flue gas passes through an absorbing tower from bottom to top, and CO2 within the fuel gas is absorbed by sprayed ammonia water; step B, carbon-containing pregnant solution is processed through thermal desorbing in a desorbing tower; step C, NH3 is removed from the desorbed gas in a washing tower, and the resulting gas is processed through a dewatering procedure by a condenser, such that carbon dioxide gas with high density isobtained; step D, weak ammonia water obtained from the above steps is pumped into an ammonia distilling tower to be concentrated; step E, concentrated ammonia water is diluted with water in an ammonia absorbing tower, such that the concentration of the ammonia water for spraying is adjusted. Correspondingly, the invention provides equipment for collecting carbon dioxide from fuel gas by using ammonia water fine spraying. The method and the equipment provided by the present invention are suitable for power stations with conditions of large flue gas flux and low carbon dioxide concentration, and assists in removing carbon dioxide effectively. According to the present invention, ammonia and water are used circularly, such that energy is saved, and cost for operation and maintenance are substantially reduced. Preferably, CO2 gas separated by the equipment is prepared into industrial grade liquid carbon dioxide.

Description

Method and equipment for capturing carbon dioxide in flue gas by fine spraying of ammonia water

technical field

The invention belongs to the field of carbon dioxide emission reduction, and in particular relates to a method and equipment for capturing carbon dioxide in power plant flue gas by fine spraying of ammonia water.

Background technique

With the increasing impact of the greenhouse effect on global climate change, controlling the emission of CO ₂ , the main greenhouse gas, has become an international and urgent problem to be solved. At present, for a long period of time, new energy cannot become the main source of energy that human beings rely on, and the contribution of energy conservation and emission reduction and improvement of energy use efficiency to carbon emission reduction is limited after all, while carbon capture and storage technology (CCS-Carbon capture and storage) storage) is considered to be an effective way to achieve carbon emission reduction. About 40% of the CO ₂ in the world is produced by fossil fuel power plants, and the proportion is even greater in China, so low-carbon or zero emissions from fossil fuel power plants are the key to reducing CO ₂ emissions. At the same time, carbon dioxide is also widely used in the chemical industry, such as the production of urea or methanol, food preservation, and enhanced oil recovery.

The capture and recovery methods of carbon dioxide in power plant flue gas mainly include the following types: chemical absorption method, physical absorption method, adsorption method, low temperature separation method, membrane separation method and biological fixation method. More industrial considerations are chemical absorption and physical absorption, among which physical absorption is more suitable for flue gas with high pressure and high _CO2 concentration; for flue gas from fossil fuel power plants, its carbon dioxide concentration is low and the flue gas flow High, a reasonable way to decarbonize is to use chemical absorption. The principle of the chemical absorption method is to use the acidic characteristics of CO ₂ to make carbon dioxide react with chemical reagents and be absorbed to generate rich liquid (liquid with high carbon content). The rich liquid enters the regeneration tower, heats and decomposes to release carbon dioxide, so as to achieve the purpose of separating and capturing carbon dioxide, and the chemical reagents can be regenerated and recycled. At present, the commonly used chemical reagent is alcohol amine solution, and the absorption tower and regeneration tower are used to form a circulation system to capture CO ₂ . The use of alcohol amine carbon capture mainly has the following problems: first, the reaction rate between alcohol amine and carbon dioxide is low, and the absorption efficiency is not high; second, its rich solution has a corrosive effect on the system; third, due to oxidation, thermal degradation, Causes such as irreversible reaction and evaporation will cause the loss of alcohol amine solvent and the change of solution properties, and alcohol amine is a kind of relatively expensive chemical products, which will inevitably increase the cost of recovering carbon dioxide. Finally, due to the large flue gas flow rate of the power plant, the carbon dioxide concentration is not high (about 10-15%). When the alcohol amine solution is used to remove carbon dioxide, the volume of the absorption tower will be large, and the construction, operation and equipment maintenance will be difficult.

Compared with traditional ethanolamine (MEA) to absorb CO ₂ , the ammonia water absorption technology has the advantages of low material cost, high absorption efficiency, strong absorption capacity, less corrosion to the absorption tower and low regeneration energy consumption. Existing research on the removal rate of _CO2 absorbed by ammonia water shows that under proper conditions, the removal rate of _CO2 in flue gas can be maintained between 95% and 99%. For example, in Chinese patent documents CN101423214A and CN201333374Y, there are reports of using ammonia water to absorb carbon dioxide in flue gas. In CN201333374Y, a device for capturing carbon dioxide in the flue gas of a power station by ammonia method is described, including an absorption tower, a regeneration tower, a water washing tower, etc.; wherein the absorption tower is an empty tower structure, and there are porous plates, two-stage ammonia water in it Spraying device and defogging device, ammonia water captures carbon dioxide in the absorption tower to generate ammonium bicarbonate rich liquid, ammonium bicarbonate decomposes in the regeneration tower to release carbon dioxide, and ammonia gas is washed by process water in the water washing tower to generate ammonia water for recycling; A gas-liquid separator, a dryer, a compressor, a condenser and a liquid carbon dioxide storage tank are connected after the water washing tower to extract the carbon dioxide separated from the flue gas into an industrial-grade liquid product.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method and equipment for effectively reducing carbon dioxide emissions in power plant flue gas, which can adapt to the characteristics of large gas flow and low carbon dioxide concentration in power plant flue gas; and the method and equipment Compared with the prior art, the ammonia and water are used in a closed cycle, which saves more energy and reduces operating costs.

The carbon removal technical solution provided by the present invention is a method for capturing carbon dioxide in flue gas by fine spraying of ammonia water, which is characterized in that it includes the following steps:

Step A, ammonia water spraying to absorb CO ₂ : the flue gas is introduced from the flue gas inlet below the absorption tower, and at the same time, a certain concentration of ammonia solution is sprayed into the absorption tower from the top of the tower in a fine spray state, and it contacts with the flue gas countercurrently. The carbon dioxide is absorbed by ammonia water, and the generated carbonized ammonia water rich liquid falls into the bottom of the absorption tower, while the decarbonized flue gas enters the washing section at the top of the absorption tower, and the ammonia gas carried in the flue gas is washed out by clean water and the flue gas At the same time, a certain amount of dilute ammonia solution is generated in the washing section; the rich liquid falling into the bottom of the absorption tower is divided into two paths, one of which is circulated in the absorption tower in a spray state through a circulation pump. The chemical reactions that take place in this step are as follows:

Step B, desorbing _CO2 gas: In step A, the other channel of the rich liquid at the bottom of the tower enters the top of the desorption tower through the rich liquid pump and heat exchanger, and performs heating and desorption treatment to obtain a mixed gas of high-concentration carbon dioxide, ammonia and water vapor. At the same time, the poor solution of carbonized ammonia water is obtained and flows down into the dilute ammonia water tank to become dilute ammonia water solution. The corresponding chemical reaction formula of this step is:

Step C, water washing to remove NH ₃ : wash the mixed gas obtained in step B in the water washing tower, absorb the ammonia gas in the water to generate a dilute ammonia solution, and flow down into the dilute ammonia water tank, and the unabsorbed gas flows up into the condenser, where it is separated Carbon dioxide gas and liquid water flow back to the washing tower.

Step D, concentration of ammonia water: the dilute ammonia solution generated in the washing section in step A is pumped to the ammonia distillation tower, and the dilute ammonia solution in the dilute ammonia water tank in steps B and C is also pumped to the ammonia distillation tower, from the ammonia distillation tower The steam at the bottom strips dilute ammonia water from bottom to top to obtain a mixture of high-concentration ammonia and water vapor, and the stripped water flows down into the circulating water tank.

Step E, adjust the concentration of ammonia water for spraying: pass the mixed gas in step D into the ammonia absorption tower, and after cooling the water in the circulating water tank through the fourth heat exchanger, spray and dilute it from above the ammonia absorption tower to prepare a certain Concentration ammonia solution is recycled as a carbon dioxide absorber.

Preferably, the method further includes a step F of purifying and liquefying the gaseous carbon dioxide separated from the condenser in step C to prepare a liquid CO ₂ product. For example, the gas-liquid separation of high-concentration _CO2 after cooling treatment is carried out to remove condensed water to obtain _CO2 gas with a purity of up to 99%. After the gas is further dried, it is compressed and condensed into an industrial-grade carbon dioxide liquid product. This operation makes the flue gas at the tail of the power plant boiler turn waste into treasure, and obtain industrial-grade liquid carbon dioxide while effectively reducing greenhouse gas carbon dioxide emissions.

Preferably, in step A of the method, the mass concentration of sprayed ammonia water is 6% to 15%, the spray particle size is 30 to 100 microns, the molar ratio of ammonia in sprayed ammonia water to carbon dioxide in flue gas is greater than 2, and the reaction temperature is 10 ~50°C, the reaction pressure is 1atm~10atm. Further preferably, the mass concentration of the ammonia solution is 8%, the reaction temperature is about 35°C, and the reaction pressure is normal pressure.

Preferably, the thermal desorption temperature in step B of the method is 100-150° C.; at this desorption temperature, ammonium bicarbonate can be rapidly and completely decomposed to release carbon dioxide gas. Preferably, the temperature of water washing to remove _NH in the step C is 60-90°C; at this temperature, the spray water can absorb ammonia well, and the ammonia water generated is not easy to react with carbon dioxide, that is, under this condition, it has Good selective absorption. Preferably, the condenser cools the unabsorbed gas to 25-35°C, more preferably 25°C; thus most of the water vapor is condensed into water and removed. Preferably, the temperature for enriching ammonia water in step D is 90-120°C. Preferably, in the step E, the ammonia water prepared to a certain concentration is cooled to 10-40°C.

Correspondingly, the present invention also provides a device for capturing carbon dioxide in flue gas by fine spraying of ammonia water, which will be described in detail in the following specific embodiments with reference to the accompanying drawings.

The method and equipment provided by the invention have the following beneficial effects: firstly, the carbon dioxide in the flue gas is effectively captured, which is beneficial to realize the resource utilization of the flue gas and reduce the emission of greenhouse gases. Second, compared with the traditional -ethanolamine (MEA) method to absorb CO ₂ , the ammonia washing technology has the advantages of low material cost, less corrosion to the absorption tower and energy saving, and the removal rate of ammonia to carbon dioxide can be as high as 95% or more . Third, compared with the packed tower, the ammonia water in the spray tower is atomized to form a fine mist of 30-100 microns, which rapidly increases the gas-liquid contact area. At the same time, the rotational movement of the mist droplets enhances the turbulence of the gas-liquid two-phase interface. , help to enhance the reaction of ammonia water to absorb carbon dioxide, improve the removal efficiency of carbon dioxide, and avoid clogging caused by setting fillers. Fourth, the entire system is closed and circulated. Through the connection of absorption tower, desorption tower, water washing tower, dilute ammonia water tank, ammonia distillation tower, circulating water tank, ammonia absorption tower, reboiler and other device connections and optimized combination of operating parameters, ammonia and water can achieve Recycling can save energy and greatly reduce the cost of operation and maintenance.

Description of drawings

Fig. 1 is the equipment flowchart of ammonia water fine spray trapping carbon dioxide in the flue gas in the embodiment of the present invention; Below is the explanation in the reference numerals:

1: Flue gas inlet 9: Second heat exchanger 20: Dilute ammonia water tank

2: Absorption tower 10: The third heat exchanger 21: Desorption tower

2a: Perforated plate 11: Ammonia absorption tower 22: Condenser

2b: Ammonia water spray section 12: Second water pump 23: Water washing tower

2c: Demisting device 13: The first diluted ammonia water pump 24: Reboiler

3: The first water pump 14: Ammonia distillation tower 25: Gas-liquid separator

4: Washing section 15: The second dilute ammonia water pump 26: Dryer

5: Ammonia water pump 16: Steam inlet 27: Compressor

6: First heat exchanger 17: Circulating water tank 28: Condenser

7: Circulation pump: 18: Fourth heat exchanger 29: Liquid _CO2 storage tank

8: rich liquid pump 19: third water pump 30: flue gas outlet

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The following are only preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any changes or changes that can be easily carried out by those skilled in the art within the technical scope disclosed by the present invention are all covered by the scope of the present invention. within the scope of protection. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Fig. 1 shows that a kind of ammonia water fine spray traps the equipment of carbon dioxide in flue gas, and it comprises the absorption tower 2 that is used for trapping carbon dioxide that is connected through pipeline, is used for desorbing CO _The desorption tower 21 of gas, is used for removing Ammonia water washing tower 23, reboiler 24 for heating, dilute ammonia water tank 20, circulating water tank 17, ammonia distillation tower 14 for thickening dilute ammonia water, ammonia absorption tower 11 for ammonia water concentration preparation and for A condenser 22 for removing moisture; wherein, the absorption tower 2 is sequentially provided with a perforated plate 2a for dispersing the flue gas and an ammonia water spray section 2b from bottom to top between the lower flue gas inlet 1 and the top flue gas outlet 30 1. Washing section 4 and demisting device 2c for water washing to remove ammonia; the first path at the bottom of the absorption tower 2 is connected to the top of the perforated plate 2a through a circulation pump 7 to form a circulation path, and the other path at the bottom of the absorption tower 2 passes through the rich liquid The pump 8, the third heat exchanger 10 and the fourth heat exchanger 18 are connected to the upper inlet of the desorption tower 21, and the rich liquid is transported to the desorption tower 21; the bottom of the desorption tower 21 is bypassed and connected to a reboiler 24, that is, the desorption tower 21 lower liquid outlet is connected with reboiler 24 lower liquid inlet, and the gas outlet of reboiler 24 upper part is connected with the lower gas inlet of desorption tower 21, and the outlet of reboiler 24 bottom is connected with dilute ammonia water tank 20 inlet; The upper part of desorption tower 21 The gas outlet links to each other with the bottom inlet of water washing tower 23; The top of water washing tower 23 is connected with condenser 22, and the liquid outlet at the bottom of water washing tower 23 also links to each other with 20 inlets of dilute ammonia water tank; The liquid inlet at the top of the ammonia tower 14 is connected, and the liquid outlet at the bottom of the washing section 4 in the absorption tower 2 is also connected with the liquid inlet at the top of the ammonia distillation tower 14 through the first heat exchanger 6 and the first dilute ammonia water pump 13. The liquid outlet is connected to the circulating water tank 17, the gas outlet above the ammonia distillation tower 14 is connected to the gas inlet below the ammonia absorption tower 11; the liquid outlet at the bottom of the ammonia absorption tower 11 passes through the first heat exchanger 6 and the ammonia water pump 5 and the ammonia water on the upper part of the absorption tower 2 The spray section 2b is connected; the outlet at the bottom of the circulating water tank 17 passes through the fourth heat exchanger 18 and then is connected in three ways: the first way is connected with the liquid inlet above the water washing tower 23 through the third water pump 19, and the second way is connected with the suction tank through the second water pump 12. The liquid inlet above the ammonia tower 11 is connected, and the third path is connected to the liquid inlet above the washing section 4 in the absorption tower 2 through the third heat exchanger 10 , the second heat exchanger 9 and the first water pump 3 .

In a preferred embodiment, a gas-liquid separator 25, a drier 26, a compressor 27, a condenser 28, and a liquid carbon dioxide storage tank 29 are connected in series after the condenser 22; wherein, the gas passes through the water washing tower The condenser 22 above the 23 is connected with the inlet of the gas-liquid separator 25 from the upper gas outlet. Further preferably, the condensed water outlet of the gas-liquid separator 25 is also connected to the process inlet at the upper part of the water washing tower 23 .

In another preferred embodiment, the gas outlet at the top of the ammonia absorption tower 11 is connected to the process port below the ammonia spray section 2b of the absorption tower. The gas in this path contains relatively high concentration ammonia gas, which is further absorbed by the ammonia water spray in the absorption tower 2 during the upward process in the absorption tower 2, and is used for the removal reaction of carbon dioxide.

The corresponding workflow of the above equipment is as follows:

Absorption: After the flue gas at the tail of the boiler has been treated by conventional dust removal and desulfurization (and denitrification), it is input into the tower from the flue gas inlet 1 at the lower part of the absorption tower, and passes through the porous plate to go up. At the same time, the ammonia solution is sprayed downward with a fine mist. At about 8%, the reaction temperature is preferably 25-40°C, the reaction pressure is normal pressure, the spray particle size of the ammonia solution is 30-100 microns, the gas-liquid contact area is large, the carbon dioxide and the ammonia water undergo a rapid chemical reaction, and the carbon dioxide is quickly absorb. The flue gas after being absorbed and decarbonized by ammonia water continues to flow upwards, passes through the washing section 4 above the absorption tower, contacts with the water sprayed down from the washing section 4, absorbs the ammonia carried in the flue gas, and then passes through the demisting section at the top. After the device 2c removes the mist, the clean flue gas is directly discharged into the atmosphere. Part of the rich liquid that has absorbed carbon dioxide is re-sprayed into the absorption tower 2 in the form of a spray through the circulation pump 7 for recycling, and the other part passes through the rich liquid pump 8, the third heat exchanger 10 and the fourth heat exchanger 18 from the top of the desorption tower 21. Enter.

Desorption: The desorption tower is a packed tower with nozzles and packing layers arranged inside the tower. The ammonium bicarbonate rich liquid is sprayed on the packing layer of the desorption tower, stripped by rising steam, and heated to 100-150°C by a reboiler , Analyze the mixed gas of carbon dioxide, ammonia and water vapor, and at the same time reduce the rich solution of ammonium bicarbonate to the poor solution of ammonia water from which CO ₂ has been removed. Ammonia poor solution is introduced downwards in the dilute ammonia water tank 20.

Water washing: The high-concentration mixed gas from the top of the desorption tower is passed into the bottom of the water washing tower, and at the same time, the process water is evenly sprayed on the sieve plate of the water washing tower, and the ammonia gas in the mixed gas is absorbed by water to form a low-concentration ammonia solution. Flow into dilute ammonia water tank 20. The high-concentration carbon dioxide enters the condenser 22 above the water washing tower, and the airflow is condensed to 25-35° C., and most of the water vapor is condensed into water, which flows into the water washing tower 23 below.

Ammonia distillation and enrichment: the dilute ammonia water tank contains ammonia solution flowing down from the desorption tower and water washing tower; the concentration of ammonia water in it is relatively low, which cannot meet the concentration requirements of the spray ammonia water in the absorption tower, so it is passed into the ammonia distillation tower liquid Upper liquid inlet. In addition, the dilute ammonia water from the bottom of the washing section 4 in the absorption tower is also pumped to the ammonia distillation tower. The bottom-up steam in the ammonia distillation tower heats and strips the injected dilute ammonia water, and the ammonia gas is removed from the ammonia solution to form a mixed gas of high-concentration ammonia gas and water vapor. Simultaneously, the water after the ammonia gas is removed from the dilute ammonia water flows into the circulating water tank 17 for recycling.

Prepare ammonia water of appropriate concentration: the mixed gas of ammonia gas and water vapor exits the top of the ammonia distillation tower and enters the gas inlet below the ammonia absorption tower. The cold water poured into the ammonia absorption tower from top to bottom and the mixed gas are prepared to make an ammonia solution that meets the concentration requirements. After heat exchange with the ammonia washing liquid at the top of the absorption tower, it is condensed to 20-35°C, and finally enters the spray from the top of the absorption tower to absorb carbon dioxide.

Preparation of liquid CO ₂ : the condensed high-concentration carbon dioxide gas enters the gas-liquid separator 25, and the liquid entrained in the carbon dioxide is completely separated by centrifugation to obtain carbon dioxide gas with a purity of 99%, which flows out of the gas-liquid separator The condensate is returned to the process water inlet of the washing tower for recycling. High-purity carbon dioxide gas is dried, compressed, and condensed into liquid carbon dioxide products, which are stored in liquid _CO2 storage tanks.

Claims (10)

1. a kind of ammoniacal liquor fine spray traps the method for carbon dioxide in flue gas, is characterized in that comprising the steps: Step A, ammonia water spraying to absorb CO ₂ : the flue gas is introduced from the flue gas inlet (1) below the absorption tower (2), and at the same time, a certain concentration of ammonia solution is sprayed into the absorption tower (2) from the top of the tower in a fine spray state, In countercurrent contact with the flue gas, the carbon dioxide in the flue gas is absorbed by ammonia water, and the carbonized ammonia water-rich liquid generated falls into the bottom of the absorption tower (2), while the decarbonized flue gas enters the washing section (4) at the top of the absorption tower. The ammonia gas carried in the flue gas is eluted by clean water, and the flue gas is discharged into the atmosphere, and a certain amount of dilute ammonia solution is generated in the washing section; the rich liquid falling into the bottom of the absorption tower (2) is divided into two paths, one of which is circulated The pump (7) circulates in the absorption tower in a spray state; Step B, desorbing CO ₂ gas: in step A, the other channel of the rich liquid at the bottom of the tower enters the top of the desorption tower (21) through the rich liquid pump (8) and heat exchanger, and undergoes heating and desorption treatment to obtain high-concentration carbon dioxide and ammonia gas Mix the gas with water vapor, and simultaneously obtain the poor solution of carbonized ammonia water and flow down into the dilute ammonia water tank (20) to become a dilute ammonia water solution; Step C, water washing to remove NH ₃ : wash the mixed gas obtained in step B in the water washing tower (23), and the clean water absorbs the ammonia gas to generate a dilute ammonia solution, which flows down into the dilute ammonia water tank (20), and the unabsorbed gas flows up into the condensate device (22), wherein the carbon dioxide gas is separated, and the liquid water flows back to the washing tower; Step D, concentration of ammonia water: the dilute ammonia solution generated in the washing section in step A is pumped to the ammonia distillation tower (14), and the dilute ammonia solution in the dilute ammonia water tank (20) in steps B and C is also pumped to the ammonia distillation tower Tower (14), the steam from the bottom of the ammonia distillation tower (14) strips dilute ammonia water from bottom to top to obtain a mixture of high-concentration ammonia and water vapor, and the stripped water flows down to the circulating water tank ( 17) in; Step E, adjusting the concentration of ammonia water for spraying: pass the mixed gas in step D into the ammonia absorption tower (11), and cool the water in the circulating water tank (17) through the fourth heat exchanger (18), then from the ammonia absorption tower The top of the tower (11) is sprayed and diluted to prepare a certain concentration of ammonia solution, which can be recycled as a carbon dioxide absorbent. 2. The method according to claim 1, characterized in that it further comprises a step F of purifying and liquefying the gaseous carbon dioxide separated from the condenser (22) in step C to prepare a liquid CO ₂ product. 3. The method according to claim 1 or 2, characterized in that, in the step A, the mass concentration of spraying ammonia water is 6% to 15%, the spray particle size is 30 to 100 microns, and the ammonia in spraying ammonia water is The molar ratio to carbon dioxide in the flue gas is greater than 2, the reaction temperature is 10-50°C, and the reaction pressure is 1atm-10atm. 4. The method according to claim 1 or 2, characterized in that, the temperature of thermal desorption in the step B is 100-150°C; the temperature of water washing to remove _NH in the step C is 60-90°C, The condenser cools the unabsorbed gas to 25-35°C. 5. The method according to claim 1 or 2, characterized in that, in the step D, the temperature at which the ammonia water is concentrated is 90-120°C. 6. The method according to claim 1 or 2, characterized in that in the step E, the ammonia water prepared to a certain concentration is cooled to 10-40°C. 7. A device for capturing carbon dioxide in flue gas by fine spraying of ammonia water, which includes an absorption tower (2), a desorption tower (21), a water washing tower (23), a reboiler (24), and a dilute ammonia water tank connected through pipelines (20), circulating water tank (17), ammonia distillation tower (14), ammonia absorption tower (11) and condenser (22); wherein, in the absorption tower (2) from the lower flue gas inlet (1) to the top A perforated plate (2a), an ammonia water spray section (2b), a washing section (4) and a demisting device (2c) are sequentially arranged between the flue gas outlets (30); the bottom of the absorption tower (2) The first path is connected to the top of the perforated plate (2a) through the circulation pump (7) to form a circulation path, and the other path at the bottom of the absorption tower (2) passes through the rich liquid pump (8), the third heat exchanger (10) and the fourth heat exchanger The heater (18) is connected to the upper inlet of the desorption tower (21), and the rich liquid is transported to the desorption tower (21); the bottom of the desorption tower (21) is connected with a reboiler (24) in a bypass cycle, and the reboiler (24) The bottom outlet is connected to the inlet of the dilute ammonia water tank (20); the upper gas outlet of the desorption tower (21) is connected to the lower inlet of the water washing tower (23); the condenser (22) is connected above the water washing tower (23), and the water washing tower (23) The bottom liquid outlet is also connected to the inlet of the dilute ammonia water tank (20); the outlet of the dilute ammonia water tank (20) is connected to the liquid inlet above the ammonia distillation tower (14) through the second dilute ammonia water pump (15), and there is another absorption tower (2) The liquid outlet below the washing section (4) is also connected to the liquid inlet above the ammonia distillation tower (14) through the first heat exchanger (6) and the first dilute ammonia water pump (13), and the liquid outlet below the ammonia distillation tower (14) is connected to the circulation The water tank (17) is connected, the gas outlet above the ammonia distillation tower (14) is connected to the gas inlet below the ammonia absorption tower (11); the liquid outlet at the bottom of the ammonia absorption tower (11) passes through the first heat exchanger (6) and the ammonia water pump (5 ) is connected with the ammonia water spray section (2b) on the upper part of the absorption tower (2); the outlet below the circulating water tank (17) passes through the fourth heat exchanger (18) and then is connected in three ways: the first way passes through the third water pump (19) and The liquid inlet above the washing tower (23) is connected, the second path is connected to the liquid inlet above the ammonia absorption tower (11) through the second water pump (12), and the third path passes through the third heat exchanger (10), the second heat exchanger (9) and the first water pump (3) are connected to the liquid inlet above the washing section (4) in the absorption tower (2). 8. The equipment according to claim 7, characterized in that, after the condenser (22), a gas-liquid separator (25), a dryer (26), a compressor (27), a condenser Device (28), liquid carbon dioxide storage tank (29). 9. The equipment according to claim 7, characterized in that the condensed water outlet of the gas-liquid separator (25) is also connected to the upper process inlet of the water washing tower (23). 10. The equipment according to any one of claims 7 to 9, characterized in that the gas outlet at the top of the ammonia absorption tower (11) is connected to the process port below the ammonia spray section (2b) of the absorption tower.

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