Apparatus and method for producing ammonium bicarbonate by using ammonia to capture carbon dioxide in flue gas

Abstract

An apparatus and method for producing ammonium bicarbonate by using ammonia to capture carbon dioxide in flue gas. According to the apparatus and method, by means of temperature control, ammonia absorbs carbon dioxide, and crystallization is carried out in the apparatus to produce ammonium bicarbonate, and by means of temperature control and zone control, ammonia escape is reduced or avoided.

Description

An apparatus and method for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia. Technical Field

[0001] This invention belongs to the field of environmental protection technology, specifically relating to an apparatus and method for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia. Background Technology

[0002] Currently, countries worldwide are seeking and developing methods to capture CO2 from industrial waste gases. The most prominent technology, CCUS (Carbon Dioxide-Screening System), suffers from high capture costs, and the utilization and storage of captured CO2 are technically challenging and prohibitively expensive. For nearly thirty years, countries have failed to achieve technological breakthroughs outside of CCUS, leaving a lack of reliable technological means for achieving carbon neutrality by 2050. Therefore, finding an efficient and cost-effective method for CO2 utilization or treatment has become a pressing issue for all countries. Ammonium bicarbonate, a fast-acting nitrogen fertilizer with the molecular formula NH4HCO3, is readily soluble in water and easily decomposes, making it suitable for various crops and soil types. Carbon dioxide is one of the raw materials for producing ammonium bicarbonate. Capturing CO2 from industrial waste gases and processing it into ammonium bicarbonate not only solves the problem of direct CO2 emissions into the atmosphere but also produces low-cost ammonium bicarbonate fertilizer—this is the research outcome of this patent. The technology has passed national-level technical appraisal and reached the world's leading level. It also won the Excellence Award (the highest award) in the 2022 Ministry of Science and Technology's Disruptive Technology Innovation Competition and was listed by the National Development and Reform Commission as a national carbon capture demonstration technology supported by the central government in 2023.

[0003] CN101830483A discloses a production method for synthesizing ammonium bicarbonate fertilizer using CO2 waste gas. The method involves countercurrent contact between CO2 waste gas (after dust removal and desulfurization) and concentrated ammonia water to generate ammonium bicarbonate. Ammonia from the preceding process is recovered via an ammonia recovery tower, and the remaining waste gas is directly discharged into the atmosphere. While this process can produce ammonium bicarbonate through countercurrent contact absorption of concentrated ammonia water and CO2-containing gas, it only describes the basic principles of a chemical reaction. Because it lacks cooling measures and does not implement zoned control for ammonium bicarbonate generation and CO2 absorption, the absorption efficiency is low, ammonia escape is severe, and it lacks industrial application prospects.

[0004] CN113262625A discloses an integrated ammonia-based desulfurization and decarbonization device and method. Ammonia is used as the desulfurization and decarbonization agent. Gas first enters the desulfurization unit for desulfurization, producing ammonium sulfate fertilizer. The desulfurized gas then enters the decarbonization unit to remove carbon dioxide, producing ammonium bicarbonate fertilizer. The decarbonized gas contains free ammonia, which is washed with a desulfurization circulating liquid, followed by washing with water. The washing liquid is returned to the desulfurization tower as an absorbent for desulfurization. The decarbonization unit is not specifically disclosed in this process.

[0005] CN114870599A discloses an apparatus and method for producing ammonium bicarbonate using an ammonia-based decarbonation system. The apparatus includes a cooling zone, an ammonium bicarbonate generation zone, a carbon dioxide absorption zone, and an ammonia removal zone. The cooling zone removes heat from the decarbonation system; the ammonium bicarbonate generation zone generates ammonium bicarbonate; the carbon dioxide absorption zone absorbs carbon dioxide from the process gas using a multi-stage absorption process; and the ammonia removal zone removes ammonia from the decarbonized process gas, with the ammonia absorbent primarily added from the carbon dioxide absorption zone. The process does not specifically disclose the equipment and control methods for ammonium bicarbonate crystallization. Summary of the Invention

[0006] This invention relates to an apparatus and method for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia. The apparatus and method are characterized by using temperature control to allow ammonia to crystallize and produce ammonium bicarbonate within the apparatus while absorbing carbon dioxide. Temperature control, zone control, and washing are used to reduce or prevent ammonia escape.

[0007] An apparatus for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia includes a temperature control zone, an ammonium bicarbonate crystallization zone, a carbon dioxide absorption zone, and an ammonia removal zone, wherein...

[0008] The temperature regulation zone is used to regulate the temperature of the decarbonized gas to meet subsequent requirements. The ammonium bicarbonate crystallization zone is used to generate ammonium bicarbonate crystallization slurry. The carbon dioxide absorption zone is mainly used to absorb carbon dioxide in the flue gas. The ammonia removal zone is used to remove ammonia from the decarbonized flue gas.

[0009] The temperature control in this invention involves temperature control in multiple zones, such as temperature regulation zone, ammonium bicarbonate crystallization zone, carbon dioxide absorption zone, and ammonia removal zone.

[0010] The ammonium bicarbonate crystallization zone is equipped with reaction and crystallization heat removal equipment.

[0011] The ammonium bicarbonate slurry produced by ammonium bicarbonate crystallization is processed into solid ammonium bicarbonate through a post-processing system, and the ammonium bicarbonate mother liquor is returned to the decarbonization unit.

[0012] The temperature control zone, ammonium bicarbonate crystallization zone, carbon dioxide absorption zone, and ammonia removal zone can be formed as independent towers or combined into a tower.

[0013] The ammonium bicarbonate crystallization zone is equipped with a gas distribution device.

[0014] The ammonium bicarbonate crystallization zone is equipped with a solid suspension device, which can be used for decarbonization gas agitation. Bubbling agitation can be achieved through an aeration device. The aeration device consists of pipes with vents distributed across the cross-section of the tower, with the vents pointing downwards or at an angle downwards, allowing gas to bubble downwards from the vents.

[0015] A method for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia involves temperature control so that ammonia crystallizes within the device while absorbing carbon dioxide, thereby reducing or preventing ammonia escape.

[0016] The system receives flue gas requiring decarbonization and sequentially passes it through a temperature regulation zone, an ammonium bicarbonate crystallization zone, a carbon dioxide absorption zone, and an ammonia removal zone.

[0017] The temperature regulation zone is used to regulate the temperature of the flue gas to meet the needs of subsequent absorption and crystallization. The ammonium bicarbonate crystallization zone produces ammonium bicarbonate slurry. The carbon dioxide absorption zone is mainly used to absorb carbon dioxide in the flue gas. The ammonia removal zone is used to remove ammonia from the decarbonized flue gas. The ammonia absorbent used to remove carbon dioxide is mainly added from the carbon dioxide absorption zone.

[0018] The ammonium bicarbonate slurry produced in the ammonium bicarbonate generation zone is processed into solid ammonium bicarbonate through a post-processing system.

[0019] The carbon dioxide content in flue gas 1 is generally low, ranging from 9% to 35% by volume. After pretreatment, the temperature is 40-60℃. Pretreatment typically includes denitrification, dust removal, and desulfurization. The temperature of flue gas 1 is controlled at 15-40℃, preferably 25-40℃, such as 30-35℃, via cooling tower 2. Crystallization tower 3 uses cooling device 11 to remove reaction heat and crystallization heat, maintaining the flue gas temperature at 15-40℃, preferably 25-35℃, which is conducive to ammonium bicarbonate crystallization. The temperature of carbon dioxide absorption tower 4 is controlled at 15-40℃, or higher than the flue gas temperature of crystallization tower 3. The carbon dioxide absorption zone is equipped with at least one layer of circulating spray device and cooling device. The flue gas outlet temperature of ammonia scrubbing tower 5 is higher than the outlet temperature of absorption tower 4.

[0020] The flue gas inlet of crystallization tower 3 is connected to gas distribution device 13 and gas bubbling agitator 12. 60% (by volume) or more of the flue gas enters gas distribution device 13, and the remaining flue gas enters gas bubbling agitator 12. This ensures sufficient gas-liquid contact and agitation. Both gas distribution device 13 and gas bubbling agitator 12 are located below the liquid level, with gas distribution device 13 positioned above gas bubbling agitator 12. Gas distribution device 13 is 0.2-2.5 meters above the liquid level, which can evenly distribute the gas while enhancing the gas-liquid reaction and promoting ammonium bicarbonate formation. Gas bubbling agitator 12 is 0.1-2 meters from the bottom of the tower to prevent ammonium bicarbonate crystallization and deposition. Absorbed ammonia is added to absorption tower 4.

[0021] The temperature control zone, ammonium bicarbonate crystallization zone, carbon dioxide absorption zone, and ammonia removal zone can be combined into one or more towers, and each zone is equipped with equipment / components that allow gas to pass through.

[0022] The crystallization tower 3 is also equipped with a stirring device 12 to prevent the deposition of ammonium bicarbonate solids. The stirring device 12 can be agitated by a stirrer or by gas bubbling. Bubbling can be achieved through an aeration device. The aeration device uses pipes with vents distributed across the cross-section of the tower, with the vents facing downwards or at an angle downwards, and the gas bubbling downwards from the vents. When gas bubbling is used, the stirring gas can be drawn from air by a separately installed blower or from the flue gas treated by the cooling tower 2.

[0023] By combining the above methods, the production of ammonium bicarbonate from carbon dioxide in the flue gas can be controlled, and ammonium bicarbonate crystals can be generated in the crystallization tower 3, while reducing ammonia escape.

[0024] Under design conditions, liquid ammonia is used as the absorbent to remove 80% of the CO2 from the flue gas, producing ammonium bicarbonate fertilizer that meets the requirements of GB3559-2001 standard, with ammonia slip ≤3mg / Nm³. 3 .

[0025] The present invention also relates to the following embodiments:

[0026] 1. An apparatus for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia, characterized in that the apparatus uses temperature control to allow ammonia to crystallize and produce ammonium bicarbonate within the apparatus while absorbing carbon dioxide, and reduces or avoids ammonia escape through temperature control, zone control, and washing.

[0027] 2. The apparatus as described in embodiment 1, wherein the partitions include a temperature control zone, an ammonium bicarbonate crystallization zone, a carbon dioxide absorption zone, and an ammonia removal zone, wherein,

[0028] The temperature regulation zone is used to regulate the temperature of the decarbonized gas to meet subsequent requirements. The ammonium bicarbonate crystallization zone is used to generate ammonium bicarbonate crystallization slurry. The carbon dioxide absorption zone is mainly used to absorb carbon dioxide in the flue gas. The ammonia removal zone is used to remove ammonia from the decarbonized flue gas.

[0029] 3. The apparatus as described in embodiment 2, wherein the ammonium bicarbonate crystallization zone is equipped with reaction and crystallization heat removal equipment.

[0030] 4. The apparatus as described in Implementation Scheme 2, wherein the ammonium bicarbonate slurry produced by ammonium bicarbonate crystallization is processed by a post-treatment system to produce solid ammonium bicarbonate, and the ammonium bicarbonate mother liquor is returned to the decarbonization unit.

[0031] 5. In the apparatus described in Implementation Scheme 2, the temperature regulation zone, the ammonium bicarbonate crystallization zone, the carbon dioxide absorption zone, and the ammonia removal zone can be formed as independent towers or combined into towers.

[0032] 6. The apparatus as described in Implementation Scheme 2, wherein the ammonium bicarbonate crystallization formation zone is equipped with a gas distribution device.

[0033] 7. The apparatus as described in Implementation Scheme 2, wherein the ammonium bicarbonate crystallization generation zone is equipped with a solid suspension device, which can be used to stir and suspend the decarbonized gas.

[0034] 8. A method for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia, characterized in that, through temperature control, ammonia crystallizes to produce ammonium bicarbonate in the device while absorbing carbon dioxide, and ammonia escape is reduced or avoided through temperature control, zone control, and washing.

[0035] 9. The method as described in Implementation Scheme 8, comprising: receiving flue gas to be decarbonized, and causing the flue gas to sequentially flow through a temperature regulation zone, an ammonium bicarbonate crystallization zone, a carbon dioxide absorption zone, and an ammonia removal zone, wherein,

[0036] The temperature control zone is used to regulate the temperature of the flue gas to meet the needs of subsequent absorption and crystallization. The ammonium bicarbonate crystallization zone produces ammonium bicarbonate slurry. The carbon dioxide absorption zone is mainly used to absorb carbon dioxide from the flue gas. The ammonia removal zone is used to remove ammonia from the decarbonized flue gas.

[0037] The ammonia absorbent used to remove carbon dioxide is mainly added from the carbon dioxide absorption zone.

[0038] 10. The method of embodiment 8, wherein the ammonium bicarbonate slurry generated in the ammonium bicarbonate generation zone is used to produce solid ammonium bicarbonate through a post-processing system.

[0039] 11. The method as described in embodiment 8, wherein the temperature regulation zone regulates the flue gas temperature to 15°C-40°C.

[0040] 12. The method as described in embodiment 8, wherein the flue gas temperature in the ammonium bicarbonate generation zone is adjusted to 15°C-40°C.

[0041] 13. As described in Implementation Scheme 8, wherein the carbon dioxide absorption zone is provided with at least one layer of circulating spray device and cooling device to adjust the flue gas temperature to 15℃-40℃. Attached Figure Description

[0042] Figure 1 is a schematic flowchart of an independent tower-building method of an apparatus and method according to some embodiments disclosed in this invention.

[0043] The markings in Figure 1 have the following meanings: 1. Flue gas; 2. Cooling tower; 3. Crystallization tower; 4. Carbon dioxide absorption tower; 5. Ammonia washing tower; 6. Clean flue gas; 7. Solid-liquid separator; 8. Packaging machine; 9. Solid ammonium bicarbonate; 10. Ammonia; 11. Cooling device; 12. Stirring device; 13. Gas distribution equipment. Detailed Implementation

[0044] An exemplary embodiment of the apparatus and method of the present invention is described below with reference to the accompanying drawings.

[0045] This invention relates to an apparatus for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia. The apparatus includes a temperature control zone, an ammonium bicarbonate crystallization zone, a carbon dioxide absorption zone, and an ammonia removal zone. The temperature control zone can adopt any structure suitable for temperature control, and particularly includes a cooling tower 2 and related equipment; the ammonium bicarbonate crystallization zone can adopt any structure suitable for ammonium bicarbonate crystallization, and particularly includes a crystallization tower 3 and related equipment; the carbon dioxide absorption zone can adopt any structure suitable for carbon dioxide absorption, and particularly includes a carbon dioxide absorption tower 4 and related equipment; the ammonia removal zone can adopt any structure suitable for ammonia removal, and particularly includes an ammonia scrubbing tower 5 and related equipment.

[0046] The CO2-containing flue gas 1 from ammonia desulfurization first enters cooling tower 2. Here, the gas can come into countercurrent contact with the spray liquid for cooling. The spray liquid is forcibly circulated by a pump and then cooled by a heat exchanger. The spray liquid can be process water, and / or a low-concentration ammonium sulfate solution from ammonia desulfurization (e.g., ammonium sulfate concentration ≤ 5% (by weight), and / or a low-concentration ammonia-containing solution from the ammonia removal zone (e.g., ammonia content ≤ 1% (by weight)). During circulation, the spray liquid absorbs components from flue gas 1, such as ammonium sulfate from ammonia desulfurization.

[0047] The cooled gas enters the crystallization tower 3 through the gas distribution device 13, which ensures the gas is evenly distributed across the cross-section of the device. In the crystallization tower 3, the gas reacts counter-currently with the circulating liquid to produce ammonium bicarbonate. The flue gas leaving the crystallization tower 3 enters the carbon dioxide absorption tower 4. The solution in the crystallization tower 3 originates from the carbon dioxide absorption tower 4.

[0048] The crystallization tower 3 is also equipped with a stirring device 12 to prevent the deposition of ammonium bicarbonate solids. The stirring device 12 can be agitated by a stirrer or by gas bubbling. Bubbling can be achieved through an aeration device. The aeration device uses pipes with vents distributed across the cross-section of the tower, with the vents facing downwards or at an angle downwards, and the gas bubbling downwards from the vents. When gas bubbling is used, the stirring gas can be drawn from air by a separately installed blower or from the flue gas treated by the cooling tower 2.

[0049] The crystallization tower 3 is also equipped with a cooling device 11 for cooling the solution in the crystallization tower 3. The cooling device 11 can be a coil type.

[0050] In carbon dioxide absorption tower 4, the gas reacts countercurrently with the circulating liquid to produce ammonium carbonate or ammonium carbamate, and the circulating liquid is circulated by a circulating pump. A heat exchange device can be installed on the circulation pipeline of the circulating pump.

[0051] The carbon dioxide absorption tower 4 can be used for single-stage absorption or multi-stage absorption.

[0052] Ammonia 10 is added to carbon dioxide absorption tower 4 through a pipeline.

[0053] The gas passing through carbon dioxide absorption tower 4 enters ammonia scrubbing tower 5 to remove free ammonia. In ammonia scrubbing tower 5, the gas can countercurrently contact water and / or acidic solutions to absorb free ammonia. The clean flue gas 6, after ammonia removal, is then discharged. During the circulation process, components carried by the flue gas enter the circulating liquid in the ammonia scrubbing tower 5, resulting in the circulating liquid containing components such as ammonium bicarbonate (a byproduct of the initial ammonia decarbonization process) and free ammonia.

[0054] The slurry from crystallization tower 3 is pumped into solid-liquid separator 7, and the resulting solid is sent to packaging machine 8 to produce solid ammonium bicarbonate 9.

[0055] The temperature control zone, ammonium bicarbonate crystallization zone, carbon dioxide absorption zone, and ammonia removal zone can be combined into one or more towers, and each zone is equipped with equipment / components that allow gas to pass through.

[0056] The present invention provides the following Example 1 to further illustrate the beneficial technical and economic effects of the apparatus and method for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia.

[0057] Example 1

[0058] Figure 1 illustrates an apparatus for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia. Flue gas 1 contains 12% carbon dioxide and has a temperature of 45-50°C. The temperature is controlled to 15-40°C, preferably 25-40°C, or even 30-35°C, by cooling tower 2. Crystallization tower 3 uses cooling device 11 to remove reaction heat and crystallization heat, maintaining the flue gas temperature at 15-40°C, preferably 25-35°C, which is beneficial for ammonium bicarbonate crystallization. The temperature of carbon dioxide absorption tower 4 is controlled to 15-40°C, or higher than the flue gas temperature of crystallization tower 3. The outlet temperature of ammonia washing tower 5 is higher than the outlet temperature of absorption tower 4.

[0059] The flue gas inlet of crystallization tower 3 is connected to gas distribution device 13 and gas bubbling agitator 12. More than 60% (by volume) of the flue gas enters gas distribution device 13, and the remainder enters gas bubbling agitator 12. This ensures both sufficient gas-liquid contact and agitation. Both gas distribution device 13 and gas bubbling agitator 12 are located below the liquid level, with gas distribution device 13 positioned above gas bubbling agitator 12. Gas distribution device 13 is 0.2-2.5 meters above the liquid level, which enhances gas-liquid reaction and promotes ammonium bicarbonate formation while uniformly distributing the gas. Gas bubbling agitator 12 is 0.1-2 meters from the bottom of the tower to prevent ammonium bicarbonate crystallization and deposition. The absorbed ammonia is added to absorption tower 4.

[0060] By combining the above methods, the production of ammonium bicarbonate from carbon dioxide in the flue gas can be controlled, and ammonium bicarbonate crystals can be generated in the crystallization tower 3, while reducing ammonia escape.

[0061] Under design conditions, liquid ammonia is used as the absorbent to remove 80% of the CO2 from the flue gas, producing ammonium bicarbonate fertilizer that meets the requirements of GB3559-2001 standard, with ammonia slip ≤3mg / Nm³. 3 .

[0062] As can be seen from the above embodiments of the present invention, the apparatus and method for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia according to the present invention, through temperature control, zone control and washing, can achieve efficient decarbonization while controlling ammonia escape, thereby achieving excellent technical and economic effects.

[0063] The above description is merely a preferred embodiment of the present invention. Those skilled in the art, upon understanding the technical means of the present invention, will naturally be able to make variations according to actual needs, guided by the teachings of the present invention. Therefore, all equivalent variations and modifications made within the scope of the claims of this invention should still fall within the scope of the patent coverage of this invention.

Claims

1. An apparatus for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia, characterized in that, This device uses temperature control to allow ammonia to crystallize into ammonium bicarbonate within the device while absorbing carbon dioxide. Temperature control, zone control, and washing reduce or prevent ammonia escape.

2. The apparatus as described in claim 1, wherein the partitions include a temperature control zone, an ammonium bicarbonate crystallization zone, a carbon dioxide absorption zone, and an ammonia removal zone, wherein, The temperature regulation zone is used to regulate the temperature of the decarbonized gas to meet subsequent requirements. The ammonium bicarbonate crystallization zone is used to generate ammonium bicarbonate crystallization slurry. The carbon dioxide absorption zone is mainly used to absorb carbon dioxide in the flue gas. The ammonia removal zone is used to remove ammonia from the decarbonized flue gas.

3. The apparatus of claim 2, wherein the ammonium bicarbonate crystallization zone is provided with reaction and crystallization heat removal equipment.

4. The apparatus of claim 2, wherein the ammonium bicarbonate slurry produced by ammonium bicarbonate crystallization is processed by a post-treatment system to produce solid ammonium bicarbonate, and the ammonium bicarbonate mother liquor is returned to the decarbonization unit.

5. In the apparatus as described in claim 2, the temperature regulation zone, the ammonium bicarbonate crystallization zone, the carbon dioxide absorption zone, and the ammonia removal zone can be formed as independent towers or combined into towers.

6. The apparatus as described in claim 2, wherein the ammonium bicarbonate crystallization zone is provided with a gas distribution device.

7. The apparatus as described in claim 2, wherein the ammonium bicarbonate crystallization zone is provided with a solid suspension device, which can employ decarbonization gas stirring suspension.

8. A method for producing ammonium bicarbonate by capturing carbon dioxide from flue gas with ammonia, characterized in that, By controlling the temperature, ammonia absorbs carbon dioxide while crystallizing to produce ammonium bicarbonate within the device. Temperature control, zone control, and washing reduce or prevent ammonia escape.

9. The method of claim 8, comprising: The system receives flue gas requiring decarbonization and sequentially passes it through a temperature regulation zone, an ammonium bicarbonate crystallization zone, a carbon dioxide absorption zone, and an ammonia removal zone. The temperature control zone is used to regulate the temperature of the flue gas to meet the needs of subsequent absorption and crystallization. The ammonium bicarbonate crystallization zone produces ammonium bicarbonate slurry. The carbon dioxide absorption zone is mainly used to absorb carbon dioxide from the flue gas. The ammonia removal zone is used to remove ammonia from the decarbonized flue gas. The ammonia absorbent used to remove carbon dioxide is mainly added from the carbon dioxide absorption zone.

10. The method of claim 8, wherein the ammonium bicarbonate slurry generated in the ammonium bicarbonate generation zone is used to produce solid ammonium bicarbonate through a post-processing system.

11. The method of claim 8, wherein the temperature regulating zone regulates the flue gas temperature to 15°C-40°C.

12. The method of claim 8, wherein the flue gas temperature in the ammonium bicarbonate generation zone is adjusted to 15°C-40°C.

13. The method of claim 8, wherein the carbon dioxide absorption zone is provided with at least one layer of circulating spray device and cooling device to adjust the flue gas temperature to 15°C-40°C.

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