Method for solving ammonia escape in process of removing carbon dioxide by using ammonia

Abstract

A method for solving ammonia escape in a process of removing carbon dioxide by using ammonia is characterized in that firstly, residual ammonia in the process of removing carbon dioxide is washed by using an ammonia-process desulfurization solution and is returned to ammonia-process desulfurization for use, then fog drops in flue gas are washed by using process water or acidic water, and residual ammonia is returned to ammonia-process desulfurization for use, so that ammonia washing under different working conditions is carried out; therefore, near-zero emission of ammonia is achieved. Through interaction of ammonia process decarburization and ammonia process desulfurization, namely integration of ammonia process decarburization and ammonia process desulfurization, low-cost desulfurization and decarburization and high-efficiency control of ammonia escape are realized.

Description

Technical Field

[0001] The present application belongs to the field of environmental protection technology, and specifically relates to a method for solving ammonia escape in the process of removing carbon dioxide with ammonia. Background Art

[0002] Ammonia decarbonization technology is currently the best way to solve greenhouse gas emissions and is also the focus of research; however, ammonia is volatile and decarbonization needs to be carried out under alkaline conditions, which increases the amount of ammonia escape. If it is not resolved, a large amount of ammonia escape will not only increase the cost of decarbonization, but also cause secondary pollution.

[0003] Patent CN101600489A proposes a method of using SO from flue gas 2 A method for acid washing ammonia, wherein the process gas is cooled by means of a cooling liquid, and sulfur dioxide in the process gas is absorbed into the cooling liquid, thereby obtaining a cooling liquid containing sulfate. The process gas containing ammonia is brought into contact with the cooling liquid containing sulfate to remove sulfur dioxide from the process gas already in the CO 2 The treated process gas in the absorber removes ammonia. To achieve the ammonia removal effect, sulfuric acid needs to be added to the cooling liquid after the cooling liquid absorbs sulfur dioxide to control the pH value. This patent uses a cooling liquid containing sulfate to wash ammonia, which is difficult to achieve the ammonia washing effect.

[0004] CN114917743A discloses a device and method for controlling ammonia escape in an ammonia decarbonization system. Ammonia is used as a desulfurization and decarbonization agent. The gas first enters the desulfurization device for desulfurization to generate ammonium sulfate fertilizer. The desulfurized gas enters the decarbonization device to remove carbon dioxide from the gas to generate ammonium bicarbonate fertilizer. The decarbonized gas contains free ammonia, and the free ammonia in the gas is absorbed by the acidic ammonium sulfate liquid and acidic water washing liquid of the ammonia desulfurization. This patent does not realize the integration of desulfurization and decarbonization, and does not explain the final destination of the washed ammonia. Summary of the invention

[0005] The present application relates to a method for solving ammonia escape in the process of removing carbon dioxide with ammonia. First, the residual ammonia in the process of removing carbon dioxide is washed with an ammonia desulfurization solution and returned to the ammonia desulfurization for use. Then, the droplets in the flue gas and the residual ammonia are washed with process water or acidic water and returned to the ammonia desulfurization for use. Ammonia washing is performed under different working conditions to achieve near-zero ammonia emissions. In the present invention, the acidic water can come from any source, wherein the pH value of the acidic water is <7.

[0006] Ammonia decarbonization must interact with ammonia desulfurization, that is, ammonia decarbonization and ammonia desulfurization must be integrated.

[0007] The process water or acid water washing can be recycled in the decarbonization water washing area and finally 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 in the process of removing carbon dioxide with ammonia, characterized in that the residual ammonia in the process of removing carbon dioxide is firstly washed with an ammonia-based desulfurization solution and returned to the ammonia-based desulfurization for use, and then the droplets in the flue gas and the residual ammonia are washed with process water or acidic water and returned to the ammonia-based desulfurization for use, and ammonia washing is carried out under different working conditions to achieve near-zero ammonia emissions.

[0010] 2. The method described in Implementation Option 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 Implementation Option 1 is characterized in that the process water or acidic water washing can be recycled in the decarbonization water washing area and finally returned to the ammonia desulfurization area for use. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is an implementation mode of the present invention in which the tower is independently formed.

[0013] 1. Desulfurization solution ammonia washing tower; 2. Flue gas after removal of carbon dioxide; 3. Ammonia desulfurization solution; 4. Ammonia washing return liquid; 5. Water washing tower; 6. Water replenishment; 7. Water washing tower discharge liquid; 8. Clean flue gas. DETAILED DESCRIPTION

[0014] In the present invention, the flue gas first undergoes the process of ammonia desulfurization and ammonia decarbonization. The gas after carbon dioxide is removed by ammonia (i.e., flue gas after carbon dioxide is removed) 2 first enters the desulfurization solution ammonia washing tower 1, and then enters the water washing tower 5. The ammonia desulfurization solution 3 from the ammonia desulfurization device enters the desulfurization solution ammonia washing tower 1, and in particular, the ammonia desulfurization solution 3 enters the desulfurization solution ammonia washing tower 1 at a position below the position where the flue gas after carbon dioxide is removed enters, and then circulates through a pump to a position above the position where the flue gas 2 after carbon dioxide is removed enters. The desulfurization solution ammonia washing tower 1 is provided with a liquid distributor and a gas-liquid contactor, and the bottom liquid collecting tank and the upper liquid distributor of the flue gas inlet are connected by a solution pipeline, so that the ammonia desulfurization solution is circulated and washed to remove ammonia in the flue gas. Part of the washed solution in the desulfurization solution ammonia washing tower 1 returns to the ammonia desulfurization device, that is, the ammonia washing return liquid 4. In the water washing tower 5, washing is performed with a washing solution (i.e., process water or acidic water). The water washing tower 5 is provided with a liquid distributor and a gas-liquid contactor. The bottom liquid collecting tank and the upper liquid distributor of the flue gas inlet are connected by a solution pipeline, so that the washing solution is circulated to wash and remove ammonia in the flue gas and remove part of the droplets. The replenishing water 6 is the replenishing water of the process water or the replenishing water of the acidic water. The ammonia-containing solution washed in the water washing tower 5 is partially removed from the ammonia desulfurization device, i.e., the exhaust liquid 7 of the water washing tower. The clean flue gas 8 after washing is discharged.

[0015] Example:

[0016] Ningbo Jiufeng Project is the first industrial demonstration unit of this patent, which can remove 2,000 tons of carbon dioxide per year. It innovatively integrates ammonia desulfurization and ammonia decarbonization technology, uses desulfurization solution and process water or acidic water to absorb ammonia escape in the flue gas after decarbonization, and returns it to desulfurization for use. After washing, the clean flue gas NH 3 Stable control at ≤2.8mg / Nm 3 , which is better than the national standard requirements for ammonia escape and solves the world-class problem of ammonia escape control in decarbonization. The device converts ammonia escape into ammonia source supplement for the desulfurization system through graded ammonia washing with desulfurization liquid and acidic water and full recycling. Combined with the deep coupling design of desulfurization and decarbonization, it achieves near-zero ammonia emissions and CO 2 Resourceization.

[0017] Innovation:

[0018] (1) Desulfurization liquid recycling ammonia washing: Breaking through the traditional acid washing / water washing and discharge process, the desulfurization solution is directly used to absorb the ammonia escape, and at the same time returns it to the desulfurization for reuse, avoiding additional consumption and adding water treatment facilities.

[0019] (2) Fully closed-loop circulation: Ammonia wash liquid and water wash 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.

[0020] See also Figure 1 After decarbonization, the flue gas passes through the desulfurization solution washing tower 1 and the water washing tower 5 in turn, and the washing liquid is respectively recycled to the desulfurization system through the washing ammonia 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.

[0021] in conclusion:

[0022] In this embodiment, the Ningbo Jiufeng project achieves near-zero ammonia escape emissions and carbon resource utilization at low cost through integrated desulfurization and decarbonization design and an original ammonia washing process. The device has been operating stably for more than 3 years, truly embodying the circular economy. In 2022, this embodiment passed the national appraisal, and the appraisal result was internationally leading, which verified the efficiency and economy of this process method in the application of environmental protection, and provided an innovative example for the coordinated treatment of coal-fired flue gas.

[0023] However, the above is only the preferred embodiment of the present invention. After understanding the technical means of the present invention, professionals familiar with this technology can naturally make changes according to actual needs under the guidance of the present invention. Therefore, all equivalent changes and modifications made according to the scope of the patent application of the present invention should still fall within the scope of the patent of the present invention.

Claims

1. A method for solving ammonia escape in the process of removing carbon dioxide with ammonia, characterized in that: First, the residual ammonia in the carbon dioxide removal process is washed with an ammonia-based desulfurization solution and returned to the ammonia-based desulfurization process. Then, the droplets in the flue gas and the residual ammonia are washed with process water or acidic water and returned to the ammonia-based desulfurization process. Ammonia washing is carried out under different working conditions to achieve near-zero ammonia emissions.

2. The method according to claim 1, characterized in that Ammonia decarbonization must interact with ammonia desulfurization, that is, ammonia decarbonization and ammonia desulfurization must be integrated.

3. The method according to claim 1, characterized in that The process water or acid water washing can be recycled in the decarbonization water washing area and finally returned to the ammonia desulfurization area for use.

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