Method for preventing ammonia slip during carbon dioxide removal using ammonia
By employing a multi-stage washing process involving ammonia desulfurization solution and process water or acidic water, the problem of ammonia escape in ammonia decarbonization has been solved, achieving near-zero ammonia emissions and resource recovery, reducing costs and pollution.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- JIANGSU NEW CENTURY JIANGNAN ENVIRONMENTAL PROTECTION CO LTD
- Filing Date
- 2026-01-15
- Publication Date
- 2026-07-30
AI Technical Summary
In existing ammonia-based decarbonization technologies, ammonia is easily volatile, leading to increased ammonia escape, increased decarbonization costs, and secondary pollution. Furthermore, existing methods are difficult to integrate desulfurization and decarbonization, and the final destination of ammonia is unclear.
The ammonia residue remaining during the carbon dioxide removal process is washed with ammonia desulfurization solution and then returned to the ammonia desulfurization process. Combined with process water or acidic water to wash away mist droplets and residual ammonia in the flue gas, a near-zero ammonia emission is achieved through a multi-stage washing process.
It achieves near-zero ammonia emissions, reduces decarbonization costs, avoids secondary pollution, and realizes the recovery and utilization of ammonia resources through integrated desulfurization and decarbonization design.
Smart Images
Figure CN2026072769_30072026_PF_FP_ABST
Abstract
Description
A method for solving ammonia slip during the removal of carbon dioxide using ammonia Technical Field
[0001] This application belongs to the field of environmental protection technology, specifically relating to a method for solving ammonia escape during the process of removing carbon dioxide with ammonia. Background Technology
[0002] Ammonia-based decarbonization technology is currently the best method for addressing greenhouse gas emissions and is a key research focus; however, ammonia is volatile, and decarbonization requires slightly alkaline conditions, leading to increased ammonia escape. If this issue is not addressed, the large amount of ammonia escape not only increases decarbonization costs but also causes secondary pollution.
[0003] Patent CN101600489A discloses a method for acid washing ammonia using SO2 from flue gas. This method utilizes a cooling liquid to cool the process gas, absorbing sulfur dioxide from the process gas into the cooling liquid to obtain a sulfate-containing cooling liquid. The process gas containing ammonia is then contacted with the sulfate-containing cooling liquid to remove ammonia from the process gas, which has already been treated in a CO2 absorber. To achieve the desired ammonia removal effect, sulfuric acid needs to be added to the cooling liquid after absorbing sulfur dioxide to control the pH value. However, this patent uses a sulfate-containing cooling liquid for ammonia washing, which is unlikely to achieve the desired ammonia washing effect.
[0004] CN114917743A discloses a device and method for controlling ammonia escape in an ammonia-based decarbonization system. 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 absorbed by the acidic ammonium sulfate solution and acidic water washing solution from the ammonia-based desulfurization process. This patent does not achieve integrated desulfurization and decarbonization, and does not specify the final destination of the washed ammonia. Summary of the Invention
[0005] This application relates to a method for addressing ammonia escape during the carbon dioxide removal process using ammonia. First, residual ammonia from the carbon dioxide removal process is washed with an ammonia desulfurization solution and returned to the ammonia desulfurization process for reuse. Then, process water or acidic water is used to wash away droplets and residual ammonia in the flue gas and returned to the ammonia desulfurization process. Ammonia washing is performed under different operating conditions to achieve near-zero ammonia emissions. In this invention, the acidic water can come from any source, wherein the pH value of the acidic water is <7.
[0006] Ammonia-based decarbonization must interact with ammonia-based desulfurization, meaning that ammonia-based decarbonization and ammonia-based desulfurization must be integrated.
[0007] Process water or acidic water washing can be recycled in the decarbonization washing area and eventually returned to the ammonia desulfurization area for use.
[0008] The present invention also relates to the following embodiments:
[0009] 1. A method for solving ammonia escape during the removal of carbon dioxide using ammonia, characterized in that: firstly, residual ammonia from the carbon dioxide removal process is washed with an ammonia desulfurization solution and returned to the ammonia desulfurization process; then, process water or acidic water is used to wash the mist droplets and residual ammonia in the flue gas and returned to the ammonia desulfurization process, thereby implementing ammonia washing under different operating conditions to achieve near-zero ammonia emissions.
[0010] 2. The method described in Implementation Scheme 1 is characterized in that ammonia decarbonization must interact with ammonia desulfurization, that is, ammonia decarbonization and ammonia desulfurization are integrated.
[0011] 3. The method described in Scheme 1, wherein the process water or acidic water washing can be recycled in the decarbonization washing area and eventually returned to the ammonia desulfurization area for use.
[0012] The present invention also relates to further embodiments as follows:
[0013] 1. A method for solving ammonia escape during the removal of carbon dioxide using ammonia, characterized in that: the escaped ammonia is washed at low temperature using a first process water and returned to the decarbonization unit for use; the escaped ammonia is washed using an ammonia-based desulfurization solution and returned to the desulfurization unit for use; and the escaped ammonia is washed using a second process water and returned to the desulfurization unit for use, thereby implementing three-stage ammonia washing under different operating conditions to achieve near-zero ammonia emissions.
[0014] 2. The method described in Implementation Scheme 1 is characterized in that, firstly, process water is used to wash away the escaped ammonia at low temperature and return it to the decarbonization unit for use; then, ammonia desulfurization solution is used to wash away the residual ammonia and return it to the desulfurization unit for use; then, process water is used to wash away the mist droplets and residual ammonia in the flue gas, implementing three-stage ammonia washing under different operating conditions to achieve near-zero ammonia emissions.
[0015] 3. The method described in Scheme 1, characterized in that the temperature of the first process water washing reaction is controlled at 10-20℃.
[0016] 4. The method described in Scheme 1, characterized in that the washing reaction temperature of the desulfurization solution is controlled at 30-50℃.
[0017] 5. The method as described in Scheme 1, characterized in that the reaction temperature of the second process water washing is controlled at 30-50℃.
[0018] 6. The method described in Scheme 1, wherein the ammonia content in the flue gas after ammonia decarbonization is higher than 500 ppm, and the ammonia concentration after purification is not higher than 8 ppm.
[0019] 7. The method as described in Scheme 1, characterized in that the ammonia removal rate of the first process water washing is controlled to be no less than 50%.
[0020] 8. The method described in Scheme 1, characterized in that the water replenishment amount of the first process water is controlled to be less than the water consumption of the decarbonization unit.
[0021] 9. The method described in Scheme 1, characterized in that the first process water washing circulation is set in multiple stages.
[0022] 10. The method as described in Scheme 1, characterized in that the ammonia washing desulfurization solution is taken from the absorption section of the desulfurization zone and returned to the absorption section of the desulfurization zone after ammonia washing.
[0023] 11. The method as described in Scheme 1, characterized in that the ammonia washing desulfurization solution is taken from the particulate matter control section of the desulfurization zone and returned to the absorption section of the desulfurization zone after ammonia washing.
[0024] 12. The method as described in Scheme 1, characterized in that the ammonia washing with the desulfurization solution includes multi-stage desulfurization solution washing.
[0025] 13. The method described in Scheme 1, characterized in that the second process water washing circulation is set in multiple stages.
[0026] 14. The method as described in Scheme 2, characterized in that the ammonia-containing solution generated from the second process water washing is used as makeup water for washing the ammonia section of the desulfurization process.
[0027] 15. The method as described in Scheme 1, characterized in that acid is added to the ammonia washing solution of the desulfurization solution to adjust the pH.
[0028] 16. As described in Implementation Scheme 1, the three-stage ammonia washing tower can be built independently or in combination.
[0029] 17. The method described in Scheme 1 is characterized in that, firstly, the escaped ammonia is washed with low-temperature first process water and returned to the decarbonization unit for use, then the residual ammonia in the flue gas is washed with second process water, and then the residual ammonia is washed with ammonia desulfurization solution and returned to desulfurization for use, thereby implementing three-stage ammonia washing under different operating conditions to achieve near-zero ammonia emissions.
[0030] 18. The method as described in Scheme 17, characterized in that the temperature of the first process water washing reaction is controlled at 10-20°C.
[0031] 19. The method as described in Scheme 17, characterized in that the washing reaction temperature of the desulfurization solution is controlled at 30-50℃.
[0032] 20. The method as described in Scheme 17, characterized in that the water washing reaction temperature of the second process is controlled at 15-40°C.
[0033] 21. The method described in Scheme 1 is characterized in that, firstly, residual ammonia is washed with ammonia desulfurization solution and returned to desulfurization for reuse; then, escaped ammonia is washed with low-temperature first process water and returned to the decarbonization unit for reuse; then, residual ammonia in the flue gas is washed with second process water, and three-stage ammonia washing is carried out under different operating conditions to achieve near-zero ammonia emissions.
[0034] 22. The method as described in embodiment 21, characterized in that the temperature of the first process water washing reaction is controlled at 30-50°C.
[0035] 23. The method as described in Scheme 21, characterized in that the washing reaction temperature of the desulfurization solution is controlled at 30-50℃.
[0036] 24. The method as described in embodiment 21, characterized in that the water washing reaction temperature of the second process is controlled at 30-50°C. Attached Figure Description
[0037] Figure 1 illustrates an embodiment of the present invention where the tower is constructed independently.
[0038] 1. Desulfurization solution and ammonia washing tower; 2. Flue gas after carbon dioxide removal; 3. Ammonia desulfurization solution; 4. Ammonia washing return liquid; 5. Water washing tower; 6. Make-up water; 7. Water washing tower effluent; 8. Clean flue gas. Detailed Implementation
[0039] In this invention, the flue gas first undergoes ammonia desulfurization and ammonia decarbonization processes. The gas after carbon dioxide removal (i.e., the flue gas after carbon dioxide removal) 2 first enters the ammonia washing tower 1, and then the water washing tower 5. The ammonia desulfurization solution 3 from the ammonia desulfurization unit enters the ammonia washing tower 1, specifically below the entry point of the flue gas after carbon dioxide removal, and then circulates via a pump to a position above the entry point of the flue gas after carbon dioxide removal. The ammonia washing tower 1 is equipped with a liquid distributor and a gas-liquid contactor, connected to a bottom collection tank and an upper liquid distributor at the flue gas inlet via a solution pipeline, allowing the ammonia desulfurization solution to circulate and wash away ammonia from the flue gas. A portion of the washed solution in the ammonia washing tower 1 is returned to the ammonia desulfurization unit, i.e., the ammonia wash return liquid 4. In the water washing tower 5, a washing solution (i.e., process water or acidic water) is used for washing. The water washing tower 5 is equipped with a liquid distributor and a gas-liquid contactor. A solution pipe connects the bottom liquid collection tank and the upper liquid distributor at the flue gas inlet, allowing the washing solution to circulate and remove ammonia and some mist droplets from the flue gas. Makeup water 6 is either process water or acidic water. The ammonia-containing solution washed in the water washing tower 5 is partially removed from the ammonia desulfurization unit, i.e., the water washing tower effluent 7. The cleaned flue gas 8 is then discharged.
[0040] Example:
[0041] The Ningbo Jiufeng project is the first industrial-scale demonstration unit of this patent, capable of removing 2,000 tons of carbon dioxide annually. It innovatively integrates ammonia-based desulfurization and ammonia-based decarbonization technologies, using desulfurization solution and process water or acidic water to absorb ammonia escaping from the flue gas after decarbonization and returning it for reuse in the desulfurization process. After washing, the NH3 content in the clean flue gas is stably controlled at ≤2.8 mg / Nm³. 3 It surpasses the national standard requirements for ammonia escape and solves the world-class problem of controlling ammonia escape during decarbonization. The device converts ammonia escape into an ammonia source supplement for the desulfurization system through graded ammonia washing and full reuse of desulfurization liquid and acidic water. Combined with the deep coupling design of desulfurization and decarbonization, it achieves near-zero ammonia emissions and CO2 resource utilization.
[0042] Innovation points:
[0043] (1) Desulfurization liquid circulation washing ammonia: Breaking through the traditional acid washing / water washing discharge process, the desulfurization solution is directly used to absorb the escaped ammonia and return it to the desulfurization system for reuse, avoiding additional consumption and the need to increase water treatment facilities.
[0044] (2) Closed-loop circulation: both ammonia washing liquid and water washing liquid are returned to the desulfurization system, achieving near-zero loss of ammonia resources and deep coupling of desulfurization and decarbonization materials, with no waste liquid discharge from the system.
[0045] Referring to Figure 1, the decarbonized flue gas sequentially passes through the ammonia washing tower 1 and the water washing tower 5. The washing liquid is recycled back to the desulfurization system through the ammonia washing return liquid 4 and the water washing tower discharge liquid 7, forming an integrated process flow. The clean flue gas 8 finally meets the emission standards.
[0046] in conclusion:
[0047] In this embodiment, the Ningbo Jiufeng project, through integrated desulfurization and decarbonization design and a unique ammonia washing process, achieves near-zero ammonia escape emissions and carbon resource utilization at low cost. The device has been operating stably for more than 3 years, truly embodying the circular economy. In 2022, this embodiment passed national-level appraisal, and the appraisal result was internationally leading, verifying the high efficiency and economy of this process in the field of environmental protection, and providing an innovative example for the synergistic treatment of coal-fired flue gas.
[0048] 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. A method for preventing ammonia slip during the removal of carbon dioxide using ammonia, characterized in that, First, the residual ammonia from the carbon dioxide removal process is washed with ammonia desulfurization solution and returned to the ammonia desulfurization process. Then, process water or acidic water is used to wash the mist droplets and residual ammonia in the flue gas and returned to the ammonia desulfurization process. Ammonia washing is carried out under different operating conditions to achieve near-zero ammonia emissions.
2. The method as described in claim 1, characterized in that, Ammonia-based decarbonization must interact with ammonia-based desulfurization, meaning that ammonia-based decarbonization and ammonia-based desulfurization must be integrated.
3. The method as described in claim 1, characterized in that, Process water or acidic water washing can be recycled in the decarbonization washing area and eventually returned to the ammonia desulfurization area for use.