Energy-saving method and device for ammonia-based carbon capture and co-production of nitrogen fertilizer

Abstract

The present invention relates to an energy-saving method and device for ammonia-based carbon capture and the co-production of a nitrogen fertilizer. In the method of the present invention, ammonia is used as an absorbent, CO2 in flue gas is captured by means of an atmospheric pressure method, an ammonium bicarbonate fertilizer is co-produced, the temperature during absorption is controlled at 25-40°C, and air is used as a cold source to transfer heat generated by absorption. The device of the present invention comprises an ammonia-based decarbonization apparatus and an air cooler. The ammonia-based decarbonization apparatus sequentially comprises a cooling functional zone, an ammonium bicarbonate generation zone, a carbon dioxide absorption zone and an ammonia-removal functional zone along the direction in which flue gas flows. The ammonia-based decarbonization apparatus is configured to remove CO2 from the CO2-containing flue gas by using an ammonia absorber so as to generate ammonium bicarbonate. The air cooler is connected to the carbon dioxide absorption zone of the ammonia-based decarbonization apparatus, and is configured to extract heat from the carbon dioxide absorption zone of the ammonia-based decarbonization apparatus.

Description

Energy-saving ammonia method carbon capture co-production of nitrogen fertilizer method and device TECHNICAL FIELD

[0001] The present application relates to an energy-saving ammonia method carbon capture co-production of nitrogen fertilizer method and device. BACKGROUND

[0002] Ammonia decarburization technology has always been the focus of research and the best method to solve greenhouse gases. However, ammonia is volatile, and decarburization needs to be carried out under slightly alkaline conditions, resulting in an increase in ammonia escape. If not addressed, large amounts of ammonia escape not only increase the cost of decarburization, but also cause secondary pollution.

[0003] CN200880122376.2 discloses a multi-stage CO2 removal system and method for treating a flue gas stream, using an absorber vessel to contact the flue gas stream with an ionic solution containing ammonia at a low temperature of 0-20℃, while the solution of the first absorption stage has a higher temperature and a lower ammonia-carbon ratio than the solution of the third absorption stage. By controlling the lower temperature, and the third stage has a lower temperature, the ammonia escape can be reduced, but the third stage has a higher ammonia-carbon ratio, which will increase the ammonia escape. The process is carried out at a low temperature of 0-20℃, and there are problems of low decarburization efficiency and high energy consumption.

[0004] CN201110039363.2 discloses an ammonia method atmospheric capture and absorption of sulfur dioxide and carbon dioxide system and process, which first carries out desulfurization and then decarburization, and multiple heat exchangers are arranged in the desulfurization and decarburization units for controlling the absorption temperature, wherein the decarburization temperature is controlled at 40℃-50℃, and high-concentration ammonia water is used for desulfurization and decarburization, and then dilute-concentration ammonia water is used for desulfurization and decarburization, and the gas after decarburization is directly discharged. The process only uses temperature control and low-concentration ammonia water absorption, and cannot solve the problem of ammonia escape, in addition, the concentration of ammonia water cannot be too low, and low-concentration ammonia water will bring in a large amount of water, causing the desulfurization product ammonium sulfate and the decarburization product ammonium bicarbonate to be unable to crystallize.

[0005] 202223487588.7 discloses an ammonia method decarburization system, which comprises an ammonia method decarburization device and a cooling tower connected with the ammonia method decarburization device, and along the flue gas flow direction, the ammonia method decarburization device comprises a cooling functional area (2), an ammonium bicarbonate generation area (5), a carbon dioxide absorption area (7) and an ammonia removal functional area (15) in sequence, the ammonia method decarburization device is configured to remove CO2 from flue gas containing CO2 with ammonia absorbent to produce ammonium bicarbonate, and the cooling tower is configured to extract heat from the ammonia method decarburization device, wherein the temperature of the decarburization absorption circulating liquid is controlled at 20℃-30℃. The temperature control of the process needs a lower environmental temperature to be realized, and the process needs a large amount of cooling water, the cooling tower occupies a large area, and the water consumption is also large. SUMMARY

[0006] Technical problems to be solved and beneficial effects

[0007] To produce ammonium bicarbonate economically and efficiently by capturing carbon dioxide with ammonia, the present solution adopts a solution gradient control method, and under specific ammonia addition and ammonia washing conditions, ammonium bicarbonate is produced by ammonia method carbon capture at a relatively high temperature. The reaction temperature can be controlled at 25-40℃ by using an air cooler. The specific operations of the solution gradient control, ammonia addition and ammonia washing in the technical solution of the present application are as follows.

[0008] An energy-saving ammonia method carbon capture co-production nitrogen fertilizer device, comprising an ammonia method decarbonization device and an air cooler, the air cooler is connected with the ammonia method decarbonization device, along the flue gas flow direction, the ammonia method decarbonization device comprises a cooling function area 2, an ammonium bicarbonate generation area 5, a carbon dioxide absorption area 7 and an ammonia removal function area 15 in sequence, and the ammonia method decarbonization device is configured to remove CO2 from flue gas containing CO2 with ammonia absorbent to produce ammonium bicarbonate.

[0009] Regarding the solution gradient control, the carbon dioxide absorption area 7 in the technical solution of the present application can be designed with multiple stages of spraying according to the carbon dioxide concentration in the process gas and the decarbonization efficiency requirement, at least 2 stages are provided, along the flue gas flow direction, the flue gas upper source is the first stage, then in sequence is the second stage, the third stage,..., and the stages are separated by a liquid collector that only allows gas to pass through.

[0010] Regarding ammonia addition, in the technical solution of the present application, ammonia is mainly added from the second stage of the carbon dioxide absorption area 7, and the ammonia source in the first stage of the carbon dioxide absorption area 7 is only added through the supplement of the second stage. If multiple stages of spraying are provided, the circulating liquid of the previous stage is sequentially supplemented into the next stage, so that the carbonate concentration gradually accumulates.

[0011] The supplement of the ammonium bicarbonate generation area 5 is supplemented through the first stage of the carbon dioxide absorption area. No ammonia is added to the ammonium bicarbonate generation area 5 to promote the generation of ammonium bicarbonate.

[0012] The carbon dioxide absorption area 7 is provided with at least 3 stages, and the amount of ammonia added after the third stage is sequentially reduced.

[0013] Regarding ammonia washing (i.e. ammonia removal), in the technical solution of the present application, the ammonia removal function area 15 is provided with at least 2 stages of spraying 15-1 and 15-2, wherein 15-1 is process water washing to remove ammonia, the circulating liquid is forced to circulate through a pump 17-1, cooled through a heat exchange device 22, and the solution obtained by washing is supplemented into the second stage 7-2 of the carbon dioxide absorption area as an ammonia source. 15-2 is acid washing to remove ammonia, which can directly supplement sulfuric acid, or supplement the condensed water obtained from the cooling function area 2, or supplement the acidic desulfurization circulating liquid of the desulfurization device 23.

[0014] The present application also relates to the following embodiments:

[0015] 1. A method for energy saving ammonia based carbon capture co-production of nitrogen fertilizer, characterized in that ammonia is used as absorbent, CO2 in flue gas is captured by atmospheric pressure method, ammonium bicarbonate fertilizer is co-produced, the temperature of absorption process is controlled at 25-40℃, preferably 28-40℃, more preferably 30-38℃, most preferably 32-38℃, and air is used as cold source to remove the heat generated by absorption.

[0016] 2. The method according to embodiment 1, characterized in that air cooler is used for temperature control.

[0017] 3. The method according to embodiment 2, characterized in that the air cooler is in the form of wet air cooler.

[0018] 4. The method according to embodiment 1, characterized in that the heat is removed directly by air cooler or indirectly by heat exchanger.

[0019] 5. The method according to embodiment 3, characterized in that the heat is removed directly by wet air cooler, in which the circulating liquid directly enters the inlet of wet air cooling solution, and returns to the ammonia based carbon capture device from the outlet after cooling.

[0020] 6. The method according to embodiment 1, characterized in that the ammonia based carbon capture includes cooling unit, ammonium bicarbonate generation unit, absorption unit, ammonia escape control unit, and at least the absorption unit uses air cooler for temperature control.

[0021] 7. The method according to embodiment 6, characterized in that the cooling unit uses air cooler for temperature control, preferably wet air cooling.

[0022] 8. The method according to embodiment 7, characterized in that the temperature is controlled at 25-40℃.

[0023] 9. The method according to embodiment 6, characterized in that the ammonium bicarbonate generation unit uses air cooler for temperature control, preferably wet air cooling.

[0024] 10. The method according to embodiment 6, characterized in that the absorption unit includes at least 2 absorption stages, and ammonia is added to the second stage in the flue gas flow direction.

[0025] 11. The method according to embodiment 6, characterized in that the temperature of cooling unit is controlled at 25-40℃.

[0026] 12. The method according to embodiment 1, characterized in that the capture pressure is less than 90kpa (gauge pressure).

[0027] 13. The method according to embodiment 1, characterized in that after absorption, water is used to wash the escaped ammonia in flue gas, and the washing temperature is 20-40℃.

[0028] 14. The method of embodiment 13, wherein the scrubbing liquid is returned to the absorption unit.

[0029] 15. An apparatus for energy saving carbon capture and nitrogen co-production by ammonia process, wherein the apparatus comprises an ammonia process decarbonization unit and an air cooler, the ammonia process decarbonization unit comprises a cooling functional zone, an ammonium bicarbonate generation zone, a carbon dioxide absorption zone and an ammonia removal functional zone in sequence along the flue gas flow direction, the ammonia process decarbonization unit is configured to remove CO2 from flue gas containing CO2 with ammonia absorbent to produce ammonium bicarbonate, the air cooler is connected with the carbon dioxide absorption zone of the ammonia process decarbonization unit and is configured to extract heat from the carbon dioxide absorption zone of the ammonia process decarbonization unit.

[0030] 16. The apparatus of embodiment 15, wherein the air cooler is a wet air cooler, and a circulation liquid pipeline of the carbon dioxide absorption zone of the ammonia process decarbonization unit is connected with the wet air cooler.

[0031] 17. The apparatus of embodiment 15, wherein the air cooler is connected with the ammonium bicarbonate generation zone of the ammonia process decarbonization unit and is configured to extract heat from the ammonium bicarbonate generation zone of the ammonia process decarbonization unit.

[0032] 18. The apparatus of embodiment 17, wherein the air cooler is a wet air cooler, and a circulation liquid pipeline of the ammonium bicarbonate generation zone of the ammonia process decarbonization unit is connected with the wet air cooler.

[0033] 19. The apparatus of embodiment 15, wherein the air cooler is connected with the cooling functional zone of the ammonia process decarbonization unit and is configured to extract heat from the cooling functional zone of the ammonia process decarbonization unit.

[0034] 20. The apparatus of embodiment 19, wherein the air cooler is a wet air cooler, and a circulation liquid pipeline of the cooling functional zone of the ammonia process decarbonization unit is connected with the wet air cooler.

[0035] 21. The apparatus of embodiment 15, wherein the air cooler is connected with the ammonia removal functional zone of the ammonia process decarbonization unit and is configured to extract heat from the ammonia removal functional zone of the ammonia process decarbonization unit.

[0036] 22. The apparatus of embodiment 21, wherein the air cooler is a wet air cooler, and a circulation liquid pipeline of the ammonia removal functional zone of the ammonia process decarbonization unit is connected with the wet air cooler. BRIEF DESCRIPTION OF DRAWINGS

[0037] FIG. 1 is a schematic diagram illustrating an embodiment of the present application.

[0038] FIG. 2 is a schematic diagram of a cooling tower cooling device used as a heat exchange device in an embodiment of the present application.

[0039] Figure 3 is a schematic diagram of an air cooling device used as a heat exchange device in the embodiment of the present application.

[0040] Figure 4 is a schematic diagram of a wet air cooling device used as a heat exchange device in the embodiment of the present application.

[0041] The following reference signs are used in the figure: process gas 1, cooling function zone 2, cooling circulation pump 3, heat exchange device 4, ammonium bicarbonate generating zone 5, liquid collector 6, carbon dioxide absorption zone 7, heat exchange device 8, ammonium bicarbonate generating zone circulation pump 9, carbon dioxide absorption zone circulation pump 10, heat exchange device 11, second section of the scrubbing liquid to the carbon dioxide absorption zone 12, process water 13, ammonium bicarbonate fertilizer 14, ammonia removal function zone 15, decarbonated gas 16, ammonia removal function zone water washing circulation pump 17, mother liquor return pipe 18, ammonia adding device 19, ammonia 20, ammonium bicarbonate discharge pump 21, heat exchange device 22, desulfurization device 23, ammonium sulfate fertilizer 24, circulation liquid in 25, circulation liquid out 26, tube and shell heat exchanger 27, cooling water in 28, cooling water out 29, circulation water pump 30, cooling tower 31, air cooler 32, wet air cooler 33. DETAILED DESCRIPTION

[0042] The process gas (also referred to as flue gas) 1 containing SO2and CO2passes through the ammonia desulfurization device 23 to produce ammonium sulfate 24 by removing SO2, and then enters the ammonia decarbonization device, which includes the cooling function zone 2, the ammonium bicarbonate generating zone 5, the carbon dioxide absorption zone 7, and the ammonia removal function zone 15.

[0043] The process gas containing SO2, CO2and ammonium sulfate particulate matter after desulfurization first enters the cooling function zone 2, and the temperature of the process gas is controlled at 25-40°C, preferably 30-38°C.

[0044] The cooling function zone 2 can be indirect heat exchange between heat exchangers to cool the process gas.

[0045] The cooling function zone 2 can also be a spray type direct contact cooling, in which the gas is cooled by countercurrent spray contact with the circulating liquid, which is circulated by the cooling circulation pump 3, and the circulating liquid is cooled by the heat exchange device 4. The cooling function zone is provided with at least 2 layers of spray.

[0046] The cooled gas enters the ammonium bicarbonate formation zone 5 where it is contacted with the circulating liquid in counter current spray to form ammonium bicarbonate. The circulating liquid is circulated by the circulating pump 9 and cooled by the heat exchange equipment 8. The gas leaving the ammonium bicarbonate formation zone 5 enters the carbon dioxide absorption zone 7. The circulating liquid of the carbon dioxide absorption zone 7 is circulated by the circulating pump 9. The carbon dioxide absorption zone 7 is separated from the ammonium bicarbonate formation zone 5 by a gas passable collector 6. Part of the circulating liquid of the carbon dioxide absorption zone 7 flows to the ammonium bicarbonate formation zone 5. The ammonium bicarbonate formation zone 1-3 is provided with sprays to control the temperature at 30-35°C.

[0047] In the carbon dioxide absorption zone 7, CO2 in the gas reacts with ammonia in the circulating liquid to form ammonium carbonate or carbamic acid. Part of the circulating liquid of the carbon dioxide absorption zone 7 flows to the ammonium bicarbonate formation zone 5. In the ammonium bicarbonate formation zone 5, CO2 in the gas reacts with ammonium carbonate or carbamic acid in the circulating liquid to form ammonium bicarbonate. The carbon dioxide absorption zone 7 is provided with two sections of sprays 7-1 and 7-2 separated by a gas passable collector 6-2. The temperature is controlled at 25-40°C, preferably 28-40°C, more preferably 30-38°C, most preferably 32-38°C. The temperature is controlled by the heat exchange equipment 11.

[0048] The ammonia adding equipment 19 can be an ammonia tank. The ammonia 20 is 99.8wt% liquid ammonia added to 7-2.

[0049] The carbon dioxide absorption zone 7 can be designed with multiple sections of sprays according to the concentration of CO2 in the gas and the requirement of the decarbonization efficiency. At least two sections are provided, the first section, the second section, etc. The sections are separated by collectors which only allow gas to pass. Ammonia is mainly added to the second section of the carbon dioxide absorption zone. The first section of the carbon dioxide absorption zone only receives make-up liquid from the second section. If multiple sections of sprays are provided, the circulating liquid of the previous section is sequentially fed to the next section to gradually accumulate the concentration of the carbonate.

[0050] The gas after the carbon dioxide absorption zone 7 enters the ammonia removal function zone 15 where it is contacted with the circulating liquid in counter current spray to absorb free ammonia. The circulating liquid is circulated by the circulating pump 17. The process gas 16 after the ammonia removal is discharged from the top of the tower.

[0051] The ammonia removal function zone 15 is provided with two sections of sprays 15-1 and 15-2. The 15-1 is a water wash to remove ammonia. The circulating liquid is forced to circulate by the pump 17-1 and cooled by the heat exchange equipment 22. The solution obtained by the washing is fed to the second section 7-2 of the carbon dioxide absorption zone. The temperature of the process gas is controlled at 20-30°C by the heat exchange equipment 22. The 15-2 is an acid wash to remove ammonia. Sulfuric acid can be directly fed, or the condensed water obtained from the cooling function zone 2, or the acidic desulfurization circulating liquid from the desulfurization equipment 23 can be fed.

[0052] The circulating liquid of the ammonium bicarbonate production zone 5 is pumped into the ammonium bicarbonate treatment system to produce solid ammonium bicarbonate 14 by the ammonium bicarbonate discharge pump 11. The ammonium bicarbonate treatment system comprises a crystallization device 12, a solid-liquid separation device 13, and the mother liquor 18 is returned to the carbon dioxide absorption zone 7.

[0053] The heat exchange devices 4, 8, 11, 22 can use air as a cold source to remove heat, and these heat exchange devices are used to cool the respective circulating liquid 25. As shown in Fig. 2, the circulating liquid 25 that needs to be cooled enters the heat exchanger 27, and the cooled circulating liquid 26 is sprayed in the device. The cooling tower 31 produces circulating cooling water 28, which is pumped into the heat exchanger 27 by the circulating water pump 30, and the cooled cooling water 29 is returned to the cooling tower 31 for cooling.

[0054] As shown in Fig. 3, the circulating liquid 25 that needs to be cooled enters the heat exchanger 27, and the cooled circulating liquid 26 is sprayed in the device. The air cooler 32 produces circulating cooling water 28, which is pumped into the heat exchanger 27 by the circulating water pump 30, and the cooled cooling water 29 is returned to the air cooler 32 for cooling.

[0055] As shown in Fig. 4, the circulating liquid 25 that needs to be cooled enters the wet air cooling 33, and the cooled circulating liquid 26 is sprayed in the device. The wet air cooling 33 is sprayed by the circulating water pump 30 to cool the circulating liquid flowing inside.

[0056] Key points

[0057] In the embodiment of the present application, "using air as a cold source to remove heat generated by absorption", such devices generally include cooling towers, air coolers (including dry air coolers and wet air coolers). The heat exchange mode of the cooling tower is indirect heat exchange between the circulating liquid and the cooling water medium, and the heat transfer efficiency is reduced through the medium; the cooling limit of the dry air cooler is the dry bulb temperature, which is greater than the wet bulb temperature; the wet air cooler can directly pass the circulating liquid for cooling, and the limit temperature is the wet bulb temperature.

[0058] 1. The temperature of the carbon dioxide absorption zone 7 is controlled at 25-40℃, preferably 28-40℃, more preferably 30-38℃, and most preferably 32-38℃. However, the temperature of about 25℃ for the cooling tower is generally only achieved under the condition of very low ambient temperature (such as in northern China in winter), so the present application also illustrates that the ammonia-based decarbonization system can be operated with particularly low energy consumption and low cost, especially in winter when the ambient temperature is relatively low. In the present patent, it is found in the experiment that under the solution gradient control mode and under the specific conditions of ammonia addition and ammonia washing, the ammonia escape can still be effectively controlled at a temperature exceeding the previous experience (20-30℃). At a higher temperature, the chemical reaction rate is increased, and the corresponding decarbonization efficiency is improved; at a higher temperature, the cooling cost of decarbonization can be saved, and especially in the range of 30-40℃, the temperature control can be completely achieved by using air cooling source. Because it is at a higher temperature, the air cooler can be used, and the wet air cooler is preferred, which is referred to as a wet air cooler.

[0059] The working principle of the wet air cooler is based on the characteristic that water absorbs heat instantaneously when evaporating. When air passes through the filler layer, water evaporates into water vapor, thereby absorbing heat and reducing the temperature of the air. Compared with the dry air cooler, the wet air cooler is more advantageous when the ambient temperature is high in hot summer or when the ambient temperature is high. This is because the wet air cooler utilizes the latent heat exchange of water evaporation and the air cooling by humidification to strengthen heat transfer, and the presence of water mist can make the inlet air temperature of the air cooler close to the ambient wet-bulb temperature, thereby improving the average temperature difference of heat transfer.

[0060] Therefore, the heat exchange efficiency of the wet air cooler is improved, and the investment and operating cost is reduced. Moreover, the wet air cooler design is flexible, and one set of wet air cooler can be provided for one pump, which is convenient for arrangement.

[0061] 2. The temperature of the cooling function zone 2 is controlled at 25-40℃, preferably 30-38℃, because it is at a higher temperature, the air cooler can be used, and the wet air cooler is preferred.

[0062] 3. The temperature of the ammonium bicarbonate generation zone 5 is controlled at 25-40℃, preferably 30-38℃.

[0063] 4. The temperature of the process water ammonia washing section 15-1 is controlled at 20-40℃, and the air cooler can be used, and the wet air cooler is preferred.

[0064] 5. The present application adopts the solution gradient control mode, and under the specific conditions of ammonia addition and ammonia washing, the ammonia-based carbon capture is realized at a higher temperature to produce ammonium bicarbonate.

[0065] EMBODIMENT

[0066] The present application provides Example 1 and Comparative Example 1 to further illustrate the technical scheme of the present application.

[0067] EMBODIMENT 1

[0068] As shown in Figure 1, the flue gas 1 is 420000 Nm 3 / h, CO2 content 12.9% (volume), SO2 content 3000 mg / Nm 3 , temperature 132℃. After desulfurization, SO2 and NH3 contents are less than 10 mg / Nm 3 and 2 mg / Nm 3 , temperature 45℃, and then enters the ammonia method decarbonization device, sequentially passes through cooling functional zone 2, ammonium bicarbonate generation zone 5, carbon dioxide absorption zone 7, and ammonia removal functional zone 15 in the ammonia method decarbonization device. Wet air cooling is used to control the temperature of cooling functional zone 2, ammonium bicarbonate generation zone 5, carbon dioxide absorption zone 7, and process water ammonia removal section 15-1 at 32-38℃. No chilled water is needed. The decarbonization efficiency is 92%, and ammonia escape is 1.5 mg / Nm 3 .

[0069] Comparative Example 1

[0070] The same process and parameters are used, and the temperature of cooling functional zone 2, ammonium bicarbonate generation zone 5, carbon dioxide absorption zone 7, and process water ammonia removal section 15-1 is controlled at 15-20℃. Due to the low temperature, air cooling equipment cannot be completely used, and pre-cooling by air cooling equipment and cooling by chilled water must be used. In the case of achieving the same decarbonization efficiency and ammonia escape as in Example 1, the chilled water consumption is 1919 t / h.

[0071] The above only describes the preferred embodiments of the present application, and those skilled in the art can make changes according to actual needs under the guidance of the present application. Therefore, any equivalent changes and modifications made within the scope of the present application should still be covered by the present application.

Claims

1. A method of energy-efficient ammonia-based carbon capture co-production of nitrogen fertilizer, characterized in that, The temperature control of the absorption process is at 25-40℃, preferably 28-40℃, more preferably 30-38℃, and most preferably 32-38℃, and air is used as the cold source to remove the heat generated by the absorption.

2. The method of claim 1, wherein, An air cooler is used for temperature control.

3. The method of claim 2, wherein, The air cooler is a wet air cooler.

4. The method of claim 1, wherein, The air cooler is used to remove the heat directly or the heat exchanger is used to remove the heat indirectly.

5. The method of claim 3, wherein, The wet air cooler is used to remove the heat directly, in which the circulating liquid directly enters the wet air cooler solution inlet and returns to the ammonia carbon capture device from the outlet after cooling.

6. The method of claim 1, wherein, The ammonia carbon capture includes a cooling unit, an ammonium bicarbonate generation unit, an absorption unit, and an ammonia escape control unit, and at least the absorption unit uses an air cooler for temperature control.

7. The method of claim 6, wherein, The cooling unit uses an air cooler for temperature control, preferably a wet air cooler.

8. The method of claim 7, wherein, The temperature control is at 25-40℃.

9. The method of claim 6, wherein, The ammonium bicarbonate generation unit uses an air cooler for temperature control, preferably a wet air cooler.

10. The method of claim 6, wherein, The absorption unit includes at least two absorption stages, and ammonia is added to the second stage in the flow direction of the flue gas.

11. The method of claim 6, wherein, The cooling unit is controlled at a temperature of 25-40℃.

12. The method of claim 1, wherein, The capture pressure is less than 90kpa (gauge pressure).

13. The method of claim 1, wherein, After absorption, water is used to wash the escaped ammonia in the flue gas, and the washing temperature is 20-40℃.

14. The method of claim 13, wherein, The washing liquid returns to the absorption unit.

15. An apparatus for energy-efficient ammonia-based carbon capture co-production of nitrogen fertilizer, characterized in that, The device includes an ammonia decarbonization device and an air cooler, and along the flow direction of the flue gas, the ammonia decarbonization device includes a cooling functional area, an ammonium bicarbonate generation area, a carbon dioxide absorption area, and an ammonia removal functional area in sequence, the ammonia decarbonization device is configured to remove CO2 from flue gas containing CO2 with ammonia absorbent to produce ammonium bicarbonate, and the air cooler is connected with the carbon dioxide absorption area of the ammonia decarbonization device and is configured to extract heat from the carbon dioxide absorption area of the ammonia decarbonization device.

16. The apparatus of claim 15, wherein, The air cooler is a wet air cooler, and the circulating liquid pipeline of the carbon dioxide absorption area of the ammonia decarbonization device is connected with the wet air cooler.

17. The apparatus of claim 15, wherein, The air cooler is connected with the ammonium bicarbonate generation area of the ammonia decarbonization device and is configured to extract heat from the ammonium bicarbonate generation area of the ammonia decarbonization device.

18. The apparatus of claim 17, wherein, The air cooler is a wet air cooler, and the circulating liquid pipeline of the carbon dioxide absorption area of the ammonia decarbonization device is connected with the wet air cooler.

19. The apparatus of claim 15, wherein, The air cooler is connected with the cooling functional area of the ammonia decarbonization device and is configured to extract heat from the cooling functional area of the ammonia decarbonization device.

20. The apparatus of claim 19, wherein, The air cooler is a wet air cooler, and the circulating liquid pipeline of the cooling functional area of the ammonia decarbonization device is connected with the wet air cooler.

21. The apparatus of claim 15, wherein, The air cooler is connected with the ammonia removal functional area of the ammonia decarbonization device and is configured to extract heat from the ammonia removal functional area of the ammonia decarbonization device.

22. The apparatus of claim 21, wherein, The air cooler is a wet air cooler, and the circulating liquid pipeline of the ammonia removal functional area of the ammonia decarbonization device is connected with the wet air cooler.

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