Ammonia desulfurization and decarbonization integrated method

Abstract

The invention is applied to desulfurization and decarburization of process gas containing sulfur oxides and CO2, belongs to the field of environmental protection, and adopts ammonia as a desulfurization and decarburization agent, the gas firstly enters a desulfurization device for desulfurization to generate an ammonium sulfate fertilizer, the desulfurized gas enters a decarburization device, carbon dioxide in the gas is removed, and an ammonium bicarbonate fertilizer is generated; the decarbonized gas contains free ammonia, is washed with a desulfurization circulating solution and then is washed with water, and the washing solution returns to a desulfurization area to be used as an absorbent for desulfurization. The technology organically integrates decarburization and desulfurization technologies, adopts desulfurization circulating liquid to wash ammonia, is high in ammonia washing efficiency, successfully solves the problem of ammonia escape in the decarburization process, is simpler in process, is low in investment and operation cost, produces ammonium sulfate and ammonium bicarbonate fertilizers as byproducts, does not need to re-inject CO2 underground for storage, can use the byproduct ammonia water, and is environment-friendly. And the purposes of treating waste with waste and recycling economy are really achieved.

Description

[0001] This application is a divisional application of the Chinese patent application filed by the applicant on May 11, 2021, with the invention name "An integrated device and method for ammonia-based desulfurization and decarbonization". Technical field:

[0002] The invention belongs to the field of environmental protection technology and specifically relates to a method for removing sulfur oxides and CO by ammonia method. 2 method. Background technology:

[0003] Carbon dioxide is the main greenhouse gas, and the use of fossil energy is its main source of emissions. 2 The total amount of emissions has ranked first in the world, and China's energy structure will continue to be dominated by coal for some time. Coal energy will still be the basis for new energy peak regulation and energy security. 2 Capturing, storing and recycling greenhouse gases are of great significance for controlling and reducing greenhouse gas emissions and addressing the greenhouse effect.

[0004] At present, the main carbon capture technology used worldwide is the organic amine method (CCUS). CCUS technology mainly absorbs CO in flue gas through organic amines. 2 , and then the absorbed CO 2 Separation of amines and CO has high investment and operation costs, high system energy consumption, and 2 Storage has restricted the development and application of CCUS technology. Global technical experts have been exploring new CCU technology. 2 The reaction directly generates ammonium bicarbonate fertilizer, achieving the purpose of carbon fixation with fertilizer. Ammonium bicarbonate is a high-quality fertilizer that has been tested in many rounds of field trials in China and around the world (see attachment). Field trials of wheat, rice, corn, potatoes, soybeans and cotton in Europe, China and other places have shown that ammonium bicarbonate fertilizer has a significant carbon fixation effect, is more effective and has a lower cost than existing fertilizers.

[0005] CN201110039363.2 reports an ammonia method atmospheric pressure capture and absorption system and process of sulfur dioxide and carbon dioxide, which first performs desulfurization and then decarbonization. Multiple heat exchangers are set in the desulfurization and decarbonization units to control the absorption temperature. At the same time, high-concentration ammonia water is used for desulfurization and decarbonization, and then dilute ammonia water is used for desulfurization and decarbonization. The gas is directly discharged after decarbonization. Only low temperature and low-concentration ammonia water absorption cannot solve the ammonia escape problem. The desulfurization and decarbonization units are independent of each other. A large amount of dilute ammonia water causes the desulfurization product ammonium sulfate and the decarbonization product ammonium bicarbonate to be unable to crystallize. The desulfurization and decarbonization of the present invention are integrated and interact with each other. The desulfurization solution is introduced into the decarbonization system to wash the ammonia escape in the flue gas after decarbonization, and then returns to the desulfurization system. Summary of the invention:

[0006] In view of the above problems, the present invention combines the experience of ammonia desulfurization to invent an integrated ammonia desulfurization and decarbonization technology. During the desulfurization process, the absorption liquid and / or process gas are cooled to meet the temperature requirements of subsequent decarbonization; the ammonia-containing process gas after decarbonization is first absorbed by the desulfurization circulating liquid, and the circulating solution after absorption is returned to the desulfurization functional area for desulfurization, thereby reducing the amount of ammonia added for desulfurization; process water or acidic water can be further used to wash the exhaust gas after decarbonization, and the ammonia-containing washing water after washing is returned to the desulfurization functional area to be used as washing water replenishment for desulfurization particulate matter removal. The present invention has the following advantages:

[0007] 1. Use desulfurization absorption liquid to wash ammonia-containing process gas, with good washing effect;

[0008] 2. Desulfurization circulating liquid is used to remove ammonia from the process gas after decarbonization. The desulfurization circulating liquid after washing is directly used for desulfurization, which simplifies the process flow and realizes the integration of desulfurization and decarbonization.

[0009] 3. The ammonia-containing washing water after washing ammonia is directly used for washing and replenishing water for desulfurization particles, reducing the desulfurization replenishment water;

[0010] 4. Recycle ammonium sulfate and ammonium carbonate fertilizers without the need to convert CO 2 Reinjecting it back into the underground for storage truly achieves carbon emission reduction.

[0011] 5. Recycling ammonium bicarbonate fertilizer is a high-efficiency fertilizer with high value, which greatly reduces CO 2 Capturing costs can even lead to profitability.

[0012] Some embodiments of the present invention are described in detail below with reference to the accompanying drawings. Figure 1 A schematic flow chart of an integrated implementation method for ammonia-based desulfurization and decarbonization is shown.

[0013] Figure 1 The meanings of the reference numerals in the figure are as follows: 1. Flue gas; 2. Desulfurization zone; 3. Desulfurization circulating liquid; 4. Ammonia washing return liquid; 5. Water washing tower discharge liquid; 6. Cooling tower; 7. Carbon dioxide absorption tower; 8. Desulfurization solution ammonia washing tower; 9. Water washing tower; 10. Water replenishment; 11. Clean flue gas; 12. Ammonium bicarbonate fertilizer; 13. Ammonium sulfate fertilizer.

[0014] See also Figure 1 , the flue gas 1 enters the desulfurization zone 2, and part of the SO in the process gas is removed by the desulfurization circulating liquid 2 .

[0015] After desulfurization, the process gas enters the cooling tower 6 for cooling, and then passes through the carbon dioxide absorption tower 7 to remove part of the CO in the process gas using the decarbonization circulating liquid. 2. The gas after the removal of carbon dioxide enters the desulfurization solution ammonia washing tower 8, and then enters the water washing tower 9. The desulfurization circulating liquid 3 from the ammonia desulfurization device enters the desulfurization solution ammonia washing tower 8, so that the solution circulates and washes to remove ammonia in the flue gas. The washed solution in the desulfurization solution ammonia washing tower 8 is partially returned to the ammonia desulfurization device, that is, the ammonia washing return liquid 4. The water washing liquid is used for washing in the water washing tower 9, so that the solution circulates and washes to remove ammonia in the flue gas. The make-up water 10 is process water make-up or acidic water make-up. The washed water washing tower discharge liquid 5 in the water washing tower 9 is sent to the ammonia desulfurization device, and the clean flue gas 11 is discharged after washing.

[0016] The ammonium sulfate slurry produced by desulfurization is treated to produce ammonium sulfate fertilizer 13, and the ammonium bicarbonate slurry produced by decarbonization is treated to produce ammonium bicarbonate fertilizer 12. Brief description of the drawings:

[0018] Figure 1 A schematic flow chart of an integrated implementation method for ammonia-based desulfurization and decarbonization is shown. Example:

[0019] Example 1 (Industrial pilot project of ammonia-based desulfurization and decarbonization with by-product ammonium sulfate / ammonium bicarbonate fertilizer integrated technology (ADSC))

[0020] 1. This embodiment 1 is the first industrial demonstration project of this patent. The project produces 30,000 tons of ammonium sulfate fertilizer per year and 2,000 tons of ammonium bicarbonate fertilizer per year. The process first uses desulfurization circulating fluid to remove more than 90% of SO in boiler flue gas. 2 , using the flue gas heat to concentrate and crystallize to produce ammonium sulfate products; after desulfurization, part of the gas is used to absorb CO with decarbonization circulating liquid 2 , CO 2 The capture efficiency can reach up to 90% or more, generating ammonium bicarbonate product; the free ammonia in the decarbonization tail gas is washed with desulfurization circulating liquid, and the washing ammonia liquid is returned to the desulfurization functional area. This embodiment 1 has been running stably for more than 3 years.

[0021] 2. Products: Ammonium sulfate fertilizer products meet the GB / T 535-2020 standard; ammonium bicarbonate fertilizer products meet the GB3559-2001 standard.

[0022] 3. Technical effects:

[0023] (1) Improved comprehensive utilization rate of ammonia, clean flue gas NH 3 Concentration ≤2.8mg / Nm 3 .

[0024] (2) The project passed the national appraisal in 2022, and the appraisal committee unanimously agreed that "the project results have reached the international leading level and are recommended for promotion and application, which will provide strong technical support for my country to achieve its "dual carbon" goals."

[0025] Example 2 (Etuoke Banner Jianyuan Coal Coking Co., Ltd. uses coke oven gas to produce by-product ammonium carbonate and ammonium sulfate while removing carbon dioxide. The circular economy demonstration project integrates an annual production of 2.3 million tons of ammonium carbonate and ammonium sulfate fertilizers and removes 1.2 million tons of carbon dioxide. Green circular economy project)

[0026] 1. This embodiment 2 is a national flue gas carbon capture demonstration project of this patent. The project captures 1.2 million tons of carbon dioxide per year and produces 2.3 million tons of nitrogen fertilizer per year. The first phase captures 200,000 tons of carbon dioxide per year, produces more than 350,000 tons of ammonium bicarbonate fertilizer per year, and produces more than 50,000 tons of ammonium sulfate fertilizer per year. The process first uses a desulfurization circulating liquid to remove most of the SO in the boiler flue gas. 2 , using the flue gas heat to concentrate and crystallize to produce ammonium sulfate products; after desulfurization, part of the gas is used to absorb CO with decarbonization circulating liquid 2 , CO 2 The capture efficiency can reach up to more than 90%, generating ammonium bicarbonate product; the free ammonia in the decarbonization tail gas is washed with desulfurization circulating liquid, and the washing ammonia liquid is returned to the desulfurization functional area for reuse.

[0027] 2. Products: Ammonium sulfate fertilizer products meet the GB / T 535-2020 standard; ammonium bicarbonate fertilizer products meet the GB3559-2001 standard.

[0028] 3. Technical effect: This embodiment is the world's largest integrated ammonia-based desulfurization and decarbonization device. The first phase captures more than 200,000 tons of carbon dioxide annually. It has been selected as a national demonstration project for "comprehensive utilization of flue gas carbon capture" supported by the central government, and has received a central government subsidy of 25 million yuan, providing strong support for the country's promotion of the "pollution reduction and carbon reduction, synergistic efficiency improvement" policy.

Claims

1. An integrated method for desulfurization and decarbonization by ammonia, using ammonia to remove sulfur oxides and CO in process gas 2 , It is characterized in that The following steps are included in sequence: 1) Use desulfurization circulating fluid to remove part of the SO in the process gas 2 ; 2) Use decarbonization circulating fluid to remove part of the CO in the process gas 2 ;and 3) A portion of the free ammonia in the process gas is removed using the desulfurization circulating fluid, and the desulfurization circulating fluid is returned to the desulfurization device.

2. The method according to claim 1, Features: The products are ammonium sulfate fertilizer and ammonium bicarbonate fertilizer.

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