Device and method for controlling ammonia escape of ammonia-based decarbonization system

Abstract

A device and method for controlling ammonia escape of an ammonia-based decarbonization system. Ammonia is used as desulfurization and decarbonization agents. Gas first enters a desulfurization device to be subjected to desulfurization, so as to generate an ammonium sulfate chemical fertilizer; the desulfurized gas enters a decarbonization device to remove carbon dioxide in the gas, thereby generating an ammonium bicarbonate chemical fertilizer. The decarbonized gas contains free ammonia, and an acidic ammonium sulfate solution and an acidic water washing solution in an ammonia-based desulfurization method are used to absorb the free ammonia in the gas. According to the device and the method, ammonia escape of the ammonia-based decarbonization system is effectively controlled, and moreover, the ammonia recycled by washing can further be used for desulfurization, and the ammonia consumption is saved.

Description

Device and method for controlling ammonia escape in an ammonia decarbonization system Technical Field

[0001] The present invention belongs to the technical field of environmental protection, and in particular relates to a device and method for controlling ammonia escape in an ammonia-based desulfurization and decarbonization system. Background Art

[0002] In recent years, the greenhouse effect has gradually become one of the most serious problems facing humanity. Carbon dioxide is the most important greenhouse gas, and fossil energy use is its primary source. my country's total CO2 emissions already rank first in the world. Furthermore, China's coal-dominated energy structure will continue for some time. Coal energy will remain the foundation of new energy peak regulation and energy security. my country has pledged to the world to reach carbon peak by 2030 and achieve carbon neutrality by 2060. Capturing, storing, and utilizing CO2 in flue gas as a resource is crucial for controlling and reducing greenhouse gas emissions and addressing the greenhouse effect and global warming.

[0003] Currently, the predominant carbon capture technology used worldwide is the organic amine method, but it faces challenges such as high operating costs and large, difficult-to-treat emissions of three wastes. Both domestic and international research is actively exploring new carbon capture technologies. Compared to the organic amine method, the ammonia method offers advantages such as easy regeneration, low operating costs, and the production of the important decarbonization byproduct, ammonium bicarbonate fertilizer. Ammonium bicarbonate is a typical compound fertilizer that simultaneously provides nitrogen fertilizer and CO2 to plants. It is particularly well-suited for modern soilless agriculture and greenhouse plant growth. This truly realizes the resource utilization of CO2, completes the carbon cycle, and avoids potential secondary pollution and CO2 environmental accidents caused by underground carbon storage. Compared to the decarbonization products of organic amines, ammonia absorbs CO2 more efficiently and ammonium bicarbonate is more easily regenerated, significantly reducing decarbonization costs.

[0004] Ammonia-based decarbonization technology has long been a research focus and the best approach to addressing greenhouse gas emissions. However, ammonia is volatile, and decarbonization requires alkaline conditions, which increases ammonia escape. If unaddressed, this high level of ammonia escape not only increases decarbonization costs but also causes secondary pollution.

[0005] Patent CN113262625A proposes an integrated desulfurization and decarbonization device that uses a desulfurization circulating fluid for scrubbing to reduce some of the free ammonia in the process gas. The scrubbing fluid is then returned to the desulfurization tower for use as a desulfurization absorbent. Simply using the desulfurization circulating fluid to scrub the free ammonia in the process gas still results in significant ammonia escape. After scrubbing with the desulfurization circulating fluid and then with process water, a large amount of ammonia-containing solution is produced. Returning the solution to the desulfurization zone for use as a desulfurization absorbent disrupts the water balance of the desulfurization system and generates wastewater.

[0006] Patent CN101600489B proposes a method for acid washing ammonia using SO2 from flue gas. The process gas is cooled using a cooling liquid, and the sulfur dioxide in the process gas is absorbed into the cooling liquid, thereby producing a cooling liquid containing sulfate. The ammonia-containing process gas is brought into contact with the cooling liquid containing sulfate to remove ammonia from the process gas treated in the CO2 absorber. The cooling liquid absorbs sulfur dioxide, primarily producing sulfite. To achieve ammonia removal, sulfuric acid must be added to the cooling liquid to control its pH, significantly increasing the difficulty of controlling the device. Furthermore, the patent fails to consider the material balance of desulfurization and decarbonization as a whole system, and only partially removes sulfur dioxide to obtain sulfate.

[0007] To address the above-mentioned issues, the present invention, drawing on operational experience with ammonia-based desulfurization and decarbonization, has developed a device and method for controlling ammonia escape from an ammonia-based decarbonization system. Using ammonia as the desulfurization and decarbonization agent, the gas first enters the desulfurization unit for desulfurization. The desulfurized gas then enters the decarbonization unit to remove carbon dioxide from the gas. The decarbonized gas contains free ammonia, which is absorbed by the acidic ammonium sulfate solution and acidic water wash used in the ammonia-based desulfurization process. This invention effectively controls ammonia escape from the ammonia-based decarbonization system. Furthermore, the ammonia recovered from the washing process can be reused for desulfurization, saving ammonia consumption.

[0008] Summary of the Invention

[0009] This invention develops a device and method for controlling ammonia slip in an ammonia-based decarbonization system. Ammonia is used to remove sulfur oxides and CO2, producing ammonium sulfate and ammonium bicarbonate fertilizers. The ammonia-based desulfurization and decarbonization system comprises an ammonia-based desulfurization zone, an ammonia-based decarbonization zone, and an ammonia slip control zone. The ammonia-based desulfurization zone includes a scrubbing and cooling section, an absorption circulation section, and a particulate matter control section. The ammonia-based decarbonization zone includes a cooling and cooling section, an absorption circulation section, and an ammonia slip control zone. The ammonia slip control zone includes an acidic ammonium sulfate scrubbing system and an acidic water scrubbing system. The absorption circulation section of the ammonia-based desulfurization zone is connected to the acidic ammonium sulfate scrubbing system of the ammonia slip control zone via a pipeline. The particulate matter control section or the cooling and cooling section of the ammonia-based decarbonization zone is connected to the acidic water scrubbing system of the ammonia slip control zone via a pipeline. The ammonia-based decarbonization absorption circulation section utilizes multiple absorption stages, with minimal or no ammonia addition in the final stage to minimize NH3 slip after decarbonization.

[0010] Ammonia is used as a desulfurization and decarbonization agent. Gas first enters the desulfurization zone for desulfurization, producing ammonium sulfate fertilizer. The desulfurized gas then enters the decarbonization zone, where carbon dioxide is removed and ammonium bicarbonate fertilizer is produced. The decarbonized gas contains free ammonia, which is scrubbed and absorbed using the acidic ammonium sulfate solution and acidic water wash solution from the ammonia desulfurization process. The acidic ammonium sulfate solution uses the solution from the absorption circulation section of the ammonia desulfurization zone, with an ammonium sulfate concentration of 10-38 wt% and a pH of 4.5-6.5. The acidic water wash uses the solution from the particulate matter control section of the ammonia desulfurization zone or the cooling section of the ammonia decarbonization zone, with an ammonium sulfate concentration of 0-5 wt% and a pH of 3-7. After scrubbing in the ammonia escape control zone, the concentrations of the acidic ammonium sulfate solution and acidic water wash solution remain essentially unchanged, with a pH of 4.6-6.9 for the acidic ammonium sulfate solution and 3.5-7.5 for the acidic water wash solution.

[0011] The temperature of the acidic ammonium sulfate solution and the acidic water washing solution is 20-60°C, preferably 30-50°C.

[0012] Acidic ammonium sulfate solution and acidic water washing solution are cooled in a cooler before washing.

[0013] A liquid distributor and a gas-liquid contact component are provided in the acidic ammonium sulfate solution and the acidic water washing liquid scrubber. The liquid distributor is preferably a trough distributor, and the gas-liquid contact component is preferably a filler.

[0014] Before the free ammonia in the gas is absorbed by the acidic ammonium sulfate solution and acidic water wash solution from the ammonia desulfurization process, process water is used to wash and absorb the free ammonia. The process water is preferably desalted water, solution from the cooling section of the ammonia decarbonization functional area, or wastewater from the acidic water wash system in the ammonia escape control functional area.

[0015] At least one layer of liquid distributor is set up for the acidic ammonium sulfate liquid washing of ammonia desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system.

[0016] At least one layer of liquid distributor is set up for the acidic water washing of ammonia desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system or decarbonization system.

[0017] At least one layer of liquid distributor is set up for process water washing, and the generated ammonia solution is returned to the desulfurization system or decarbonization system.

[0018] Between the acidic ammonium sulfate solution used in ammonia desulfurization and the acidic water washing solution, a liquid collector is provided that only allows gas to pass through.

[0019] A liquid collector that only allows gas to pass is installed between the acidic ammonium sulfate liquid used for ammonia desulfurization and the process water washing.

[0020] The above-mentioned functional areas can be combined into one tower or multiple towers. In the desulfurization functional area, each section is equipped with at least one spray layer, and equipment / components that allow gas to pass through are installed between sections. The particle removal section is divided into two parts. The first part uses a high-concentration ammonium sulfate solution for spray washing, and the second part uses a dilute ammonium sulfate solution for circulation washing. Equipment / components that allow gas to pass through are installed between the two sections. In the decarbonization functional area, each section is equipped with at least one spray layer, and equipment / components that allow gas to pass through are installed between sections.

[0021] The present invention also relates to the following embodiments:

[0022] 1. A method for controlling ammonia escape in an ammonia decarbonization system, characterized in that the gas after ammonia decarbonization contains free ammonia, and the free ammonia in the gas after ammonia decarbonization is washed and absorbed by an acidic ammonium sulfate solution and an acidic water washing solution used in ammonia desulfurization.

[0023] 2. The method as described in Embodiment 1 is characterized in that before the acidic ammonium sulfate solution and acidic water wash liquid of ammonia desulfurization are used to absorb free ammonia in the gas, the method also includes washing with process water to absorb free ammonia, and the process water is preferably desalted water, washing condensate, and acidic water wash liquid drainage.

[0024] 3. The method according to embodiment 1 is characterized in that the ammonia-containing solution produced by washing with the acidic ammonium sulfate solution and the acidic water washing solution in ammonia-based desulfurization is returned to the desulfurization system or the decarbonization system.

[0025] 4. The method described in Embodiment 1 is characterized in that at least one layer of liquid distributor is provided for washing the acidic ammonium sulfate liquid in ammonia-based desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system.

[0026] 5. The method described in Embodiment 1 is characterized in that at least one layer of liquid distributor is provided for the acidic water washing of ammonia desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system or the decarbonization system.

[0027] 6. The method as described in Embodiment 2 is characterized in that at least one layer of liquid distributor is set up for process water washing, and the generated ammonia-containing solution is returned to the desulfurization system or the decarbonization system.

[0028] 7. The method according to embodiment 1 is characterized in that a device or component that only allows gas to pass is provided between the acidic ammonium sulfate solution used for ammonia desulfurization and the acidic water washing solution.

[0029] 8. The method according to embodiment 2 is characterized in that a device or component that only allows gas to pass is provided between the acidic ammonium sulfate solution for ammonia desulfurization and the process water for washing.

[0030] 9. The method described in Embodiment 1 is characterized in that the ammonia decarbonization absorption cycle section includes multi-stage absorption, in which less or no ammonia is added in the last stage to reduce NH3 escape after decarbonization.

[0031] 10. The method according to embodiment 1 is characterized in that the NH3 content in the gas after treatment in the absorption cycle section of the ammonia decarbonization functional zone is 200 to 2000 ppm; preferably 400 to 1500 ppm; more preferably 500 to 1000 ppm.

[0032] 11. The method according to embodiment 1 is characterized in that the NH3 content in the gas after treatment in the ammonia escape control functional zone is 0 to 30 ppm; preferably 0 to 20 ppm; more preferably 0 to 10 ppm.

[0033] 12. The method according to embodiment 1, wherein the acidic ammonium sulfate solution has a pH of 4.5-6.5 and an ammonium sulfate concentration of 10-38 wt %; and the acidic water wash solution has a pH of 3-7 and an ammonium sulfate concentration of 0-5 wt %.

[0034] 13. The method according to embodiment 1, characterized in that the temperature of the acidic ammonium sulfate solution and the acidic water wash solution is 20-60°C, preferably 30-50°C.

[0035] 14. The method according to embodiment 1, wherein the acidic ammonium sulfate solution and the acidic water washing solution are cooled in a cooler before washing.

[0036] 15. The method according to embodiment 2 is characterized in that the liquid-to-gas ratio of process water is generally 5-25, preferably 10-20, and more preferably 12-18.

[0037] 16. The method according to embodiment 1, wherein the liquid-to-gas ratio of the acidic ammonium sulfate solution is generally 1-20, preferably 1-10, and more preferably 2-6.

[0038] 17. The method according to embodiment 1 is characterized in that the liquid-to-gas ratio of the acidic water wash solution is generally 1-15, preferably 1-8, and more preferably 2-5.

[0039] 18. The method according to embodiment 1 is characterized in that a gas-liquid contact component is provided in the acidic ammonium sulfate solution and the acidic water washing liquid scrubber, and the gas-liquid contact component is preferably a filler.

[0040] 19. The method according to embodiment 2, wherein the pH of the process water, wash condensate, and acidic water wash drainage is no greater than 8.

[0041] 20. The method according to embodiment 2, wherein acid is added to process water, wash condensate, and acidic water wash drainage to adjust the pH, and preferably the acid is sulfuric acid.

[0042] 21. A device for controlling ammonia escape in an ammonia-based desulfurization and decarbonization system, comprising an ammonia-based desulfurization functional area, an ammonia-based decarbonization functional area, and an ammonia escape control functional area.

[0043] in,

[0044] The ammonia desulfurization functional area includes the washing and cooling section, the absorption circulation section, and the particulate matter control section.

[0045] The ammonia decarbonization functional area includes the cooling section and the absorption circulation section.

[0046] The ammonia escape control functional area includes the ammonia escape control section, including the acidic ammonium sulfate washing system and the acidic water washing system.

[0047] The absorption circulation section of the ammonia desulfurization functional area is connected to the acidic ammonium sulfate liquid washing system of the ammonia escape control functional area through a pipeline, and the particulate matter control section of the ammonia desulfurization functional area or the cooling section of the ammonia decarbonization functional area is connected to the acidic water washing system of the ammonia escape control functional area through a pipeline.

[0048] 22. The device as described in embodiment 21 is characterized in that the ammonia decarbonization absorption cycle section includes multi-stage absorption, in which less or no ammonia is added in the last stage to reduce NH3 escape after decarbonization.

[0049] 23. The device as described in Embodiment 21 is characterized in that the ammonia escape control functional area may also include a process water washing system, which is connected to the process water pipe through a pipeline and is connected to the absorption circulation section of the ammonia desulfurization device or the absorption circulation section of the ammonia decarbonization device.

[0050] 24. The device as described in Embodiment 21 is characterized in that the sections of the ammonia desulfurization functional area and the ammonia decarbonization functional area can be combined into one tower or multiple towers, and equipment / components allowing gas to pass through are provided between the sections.

[0051] 25. The device as described in Embodiment 21 is characterized in that the particulate matter control section of the ammonia desulfurization functional zone can partially or completely realize the function of the cooling section of the ammonia decarbonization functional zone. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG1 shows Example 1 of the present invention. Before the free ammonia in the gas is absorbed by the acidic ammonium sulfate solution and acidic water washing solution of ammonia desulfurization, process water is also used for washing to absorb the free ammonia.

[0053] FIG2 shows Example 2 of the present invention, in which the free ammonia in the absorption gas is scrubbed with the acidic ammonium sulfate solution and acidic water wash solution of ammonia desulfurization.

[0054] Figure 3 is a comparative example, in which process water is used for washing to absorb free ammonia.

[0055] Process gas 1, desulfurization functional area 2, desulfurization washing and cooling section 2-1, desulfurization absorption circulation section 2-2, desulfurization particulate matter control section 2-3, desulfurization circulation pump a 3, desulfurization circulation pump b 4, desulfurization circulation pump c 5, desulfurization circulation tank 6, oxidation air 7, desulfurization system ammonia addition 8, ammonium sulfate discharge pump 9, desulfurization circulation pump d 10, desulfurization heat exchanger 11, desulfurization tail gas 12, decarbonization absorption tower 13, decarbonization circulation pump 14, ammonium sulfate discharge pump 15, decarbonization system ammonia addition 16, decarbonization tail gas 17, ammonia washing tower 18, process water washing section 18-1, ammonium sulfate washing section 18-2, acid washing section 18-3, ammonia washing circulation pump a 19, desulfurization absorption section ammonium sulfate solution 20, return desulfurization liquid 21, ammonia washing circulation pump b 22, Desulfurization particulate matter control section solution 23, returned acidic solution 24, clean flue gas 25, finished product ammonium sulfate 26, finished product ammonium bicarbonate 27, process water 28, ammonia-containing solution 29, process water washing section filler 30-1, ammonium sulfate washing section filler 30-2, acid washing section filler 30-3, process water washing section trough distributor 31-1, ammonium sulfate washing section trough distributor 31-2, acid washing section trough distributor 31-3, desulfurization absorption section ammonium sulfate solution heat exchanger 32 for removing ammonia, desulfurization particulate matter control section solution heat exchanger 33 for removing ammonia. DETAILED DESCRIPTION

[0056] In the method for controlling ammonia slip in an ammonia-based decarbonization system of the present invention, the gas after ammonia-based decarbonization contains free ammonia. Specifically, the present invention utilizes the acidic ammonium sulfate solution and acidic water wash solution from the ammonia-based desulfurization process to scrub and absorb the free ammonia in the gas after ammonia-based decarbonization. Furthermore, before absorbing the free ammonia in the gas with the acidic ammonium sulfate solution and acidic water wash solution from the ammonia-based desulfurization process, the present invention also includes scrubbing with process water to absorb the free ammonia. The process water is preferably desalted water or scrubbing condensate.

[0057] In the method of the present invention, the flow rate of the acidic ammonium sulfate solution, acidic water washing solution or process water used for washing and absorption can be appropriately adjusted as needed. The liquid-to-gas ratio of the process water is usually 5-25, preferably 10-20, and more preferably 12-18; the liquid-to-gas ratio of the acidic ammonium sulfate solution is usually 1-20, preferably 1-10, and more preferably 2-6; the liquid-to-gas ratio of the acidic water washing solution is usually 1-20, preferably 1-15, and more preferably 2-10.

[0058] Liquid-gas ratio = Q / V,

[0059] Q, liquid circulation volume, L / h

[0060] V, process gas flow after ammonia decarbonization (working conditions, i.e. gas flow under operating conditions (temperature, pressure, etc.)), m 3 / h.

[0061] The treatment according to the method of the present invention mainly removes free ammonia contained in the gas after ammonia decarbonization, while having little effect on the SO2 content and CO2 content.

[0062] In the method of the present invention, the pH of the acidic ammonium sulfate solution is 4.5-6.5, the ammonium sulfate concentration is 10-38wt%, preferably 12-35wt%, more preferably 15-30wt%, and most preferably 17-28wt%; the pH of the acidic water wash solution is 3-7, the ammonium sulfate concentration is 0-5wt%, preferably 0-3wt%, more preferably 0-1wt%, and most preferably 0-0.6wt%.

[0063] In the method of the present invention, the temperature of the acidic ammonium sulfate solution and the acidic water washing solution is 20-60°C, preferably 30-50°C.

[0064] The NH3 content in the gas after treatment in the decarbonization absorption tower is 200 to 2000 ppm; preferably 400 to 1500 ppm; more preferably 500 to 1000 ppm.

[0065] The SO2 content in the gas after treatment in the decarbonization absorption tower is 0 to 20 mg / Nm 3 ; preferably 0 to 15 mg / Nm 3 More preferably 0 to 10 mg / Nm 3 .

[0066] The CO2 content in the gas after treatment in the decarbonization absorption tower is 0-20v%; preferably 1-10v%; more preferably 2-7v%.

[0067] After being treated by the method of the present invention, the NH3 content in the gas is 0 to 30 ppm; preferably 0 to 20 ppm; more preferably 0 to 10 ppm.

[0068] The method for controlling ammonia escape from an ammonia-based decarbonization system protected by the present invention is preferably carried out in an apparatus for controlling ammonia escape from an ammonia-based desulfurization and decarbonization system defined in the present invention.

[0069] The method and apparatus of the present invention achieve beneficial economic effects in addition to the technical effects, in particular reducing ammonia slip and significantly reducing ammonia consumption, specifically reducing ammonia consumption losses by 96%-99%, preferably 97%-99%, as shown in the following examples.

[0070] The method for testing the SO2 content in the gas in the present invention is HJ 629-2011 Stationary pollution source exhaust gas. Determination of sulfur dioxide. Non-dispersive infrared absorption method;

[0071] The CO2 content test method is HJ 870-2017 Determination of carbon dioxide in waste gas from stationary pollution sources - Non-dispersive infrared absorption method;

[0072] The NH3 content test method is HJ 533-2009 Determination of ammonia in ambient air and exhaust gas - Nessler's reagent spectrophotometry.

[0073] All concentrations mentioned herein are by weight unless otherwise stated.

[0074] Example

[0075] The present invention specifically provides Examples 1 and 2 and a comparative example to further illustrate the technical solution of the present invention and its beneficial effects.

[0076] Example 1

[0077] As shown in Figure 1, process gas 1 containing sulfur oxides and CO2 enters the desulfurization functional area 2 and passes through the desulfurization, washing, and cooling section 2-1, the desulfurization, absorption, and circulation section 2-2, and the desulfurization particulate matter control section 2-3. In the desulfurization, washing, and cooling section 2-1, desulfurization circulation pump-a 3 sprays and circulates the exhaust gas, simultaneously cooling the exhaust gas and concentrating the ammonium sulfate solution. The concentrated ammonium sulfate slurry, which has precipitated solids, is then delivered to the ammonium sulfate production unit 26 via the ammonium sulfate discharge pump 9. Desulfurization circulation pumps-b 4 and 5, along with the desulfurization circulation tank 6, perform absorption spray circulation to absorb sulfur oxides (sulfur dioxide and sulfur trioxide) in the exhaust gas. A portion of the ammonium sulfate solution 20 discharged by the desulfurization circulation pump-c 5 is cooled to 35°C in the cooler 32 before being sent to the ammonium sulfate washing section 18-2 of the ammonia tower. The washed solution 21 is then returned to the desulfurization circulation tank 6. The desulfurization circulation pump 10 performs a scrubbing spray cycle, and the desulfurization heat exchanger 11 controls the scrubbing temperature and the temperature of the desulfurized exhaust gas 12. The particulate matter control section 2-3 in the ammonia desulfurization functional area provides cooling for ammonia decarbonization. The acidic solution 23 condensed from the flue gas is cooled to 35°C in the cooler 33 and then used as water for the acidic water scrubbing section 18-3 of the ammonia scrubbing tower. The washed solution 24 is then returned to the desulfurization circulation tank 6. Ammonia is metered in the desulfurization system 8 and then added to the desulfurization circulation tank 6. Oxidizing air 7 is supplied to the desulfurization circulation tank 6 to oxidize the solution.

[0078] The desulfurized tail gas 12 enters the decarbonization absorption tower 13, is absorbed and circulated by the decarbonization circulation pump 14, and the finished ammonium carbonate 27 is delivered by the ammonium carbonate discharge pump 15. The decarbonization system ammonia addition 16 is metered and then sent to the decarbonization absorption tower 13 for ammonia addition.

[0079] After decarbonization, tail gas 17 enters ammonia scrubbing tower 18, passing sequentially through process water scrubbing section 18-1, ammonium sulfate scrubbing section 18-2, and acid scrubbing section 18-3. In process water scrubbing section 18-1, ammonia scrubbing circulating pump-a 19 is used for process water scrubbing. This section is equipped with a trough distributor 31-1 and packing 30-1. Process water is replenished through external process water pipe 28. The washed ammonia-containing solution 29 is then sent to decarbonization tower 13. Part of the ammonium sulfate solution 20 from the desulfurization absorption section, delivered by desulfurization circulating pump-c 5, enters ammonium sulfate scrubbing section 18-2 of the ammonia scrubbing tower. This section is equipped with a trough distributor 31-2 and packing 30-2. The washed solution (i.e., the return desulfurization solution) 21 returns to the desulfurization circulation tank 6. The acidic solution condensed from the flue gas (i.e., the solution from the desulfurization particulate matter control section) 23, delivered by desulfurization circulation pump d 10, is used to replenish the acidic water wash section 18-3 of the ammonia scrubber. This section is equipped with a trough distributor 31-3 and packing 30-3. The washed solution (i.e., the returned acidic solution) 24 is returned to the desulfurization circulation tank 6. Clean flue gas 25 is discharged after washing.

[0080] Acidic ammonium sulfate solution 20 flow 350m 3 / h, pH 6.4, ammonium sulfate concentration 18wt%, the acidic ammonium sulfate liquid returned after washing in the ammonia washing tower has a pH of 6.9, and the ammonium sulfate concentration remains basically unchanged.

[0081] The flow rate of the acidic water washing liquid 23 is adjusted according to the pH value of the water washing liquid in the acidic water washing section 18-3 of the ammonia washing tower, pH 3.8, ammonium sulfate concentration 2wt%, and the acidic water washing liquid returned after washing in the ammonia washing tower has a pH of 4.2 and ammonium sulfate concentration that remains basically unchanged. The circulation volume of the ammonia washing circulation pump b 22 is 500m 3 / h to ensure the ammonia washing effect.

[0082] The flow rate of process water 28 is adjusted according to the pH value of the water washing liquid in the process water washing section 18-1 of the ammonia washing tower, wherein the circulation volume of the ammonia washing circulation pump a 19 is 1200m 3 / h to ensure the ammonia washing effect. The pH of the demineralized water is 6.9, and the pH of the solution returned after washing in the ammonia washing tower is 7.9.

[0083] Desulfurization and decarbonization use 99.6% liquid ammonia as the absorbent. The process gas 1 parameters are shown in the table below:

[0084] The parameters of the gas 12 after desulfurization and cooling are shown in the following table:

[0085] The main parameters of gas 17 after treatment in the decarbonization absorption tower are shown in the following table:

[0086] The main parameters of gas 25 after treatment in the ammonia scrubbing tower are shown in the following table:

[0087] The ammonia escape volume is 4.98t / year, and the ammonia consumption loss is about 20,000 yuan / year.

[0088] Example 2

[0089] As shown in Figure 2, the process water washing section 18-1 is the same as in Example 1, but without the ammonia washing tower. The desulfurization and decarbonization parameters are the same. The main parameters of the gas 25 after treatment in the ammonia washing tower are shown in the following table:

[0090] The amount of ammonia escape is 8.96t / year, and the ammonia consumption loss is about 36,000 yuan / year.

[0091] Comparative Example

[0092] As shown in Figure 3, the same as in Example 1, but without the ammonium sulfate washing section 18-2 and the acidic solution washing section 18-3 of the ammonia washing tower. The desulfurization and decarbonization parameters are the same. The main parameters of the gas 25 after treatment in the ammonia washing tower are shown in the following table:

[0093] The amount of ammonia escape is 248t / year, and the ammonia loss is about RMB 992,000 / year.

[0094] From the comparison between the above embodiments of the present invention and the comparative examples, it can be seen that the amount of ammonia escape in the gas treated by the method and apparatus of the present invention is significantly reduced, so that the ammonia loss is greatly reduced, thereby achieving excellent technical and economic effects.

[0095] The above description is merely a preferred embodiment of the present invention. Those skilled in the art, once understanding the technical means of the present invention, will naturally be able to modify the present invention according to their actual needs. Therefore, all equivalent changes and modifications made within the scope of the present invention are still covered by the present invention.

Claims

1. A method for controlling ammonia escape in an ammonia decarbonization system, characterized in that: The gas after ammonia decarbonization contains free ammonia, which is washed and absorbed by the acidic ammonium sulfate solution and acidic water washing solution of ammonia desulfurization.

2. The method according to claim 1, wherein Before the free ammonia in the gas is absorbed by the acidic ammonium sulfate solution and acidic water washing liquid of ammonia desulfurization, the process water is also used for washing to absorb the free ammonia. The process water is preferably desalted water, washing condensate, and acidic water washing liquid drainage.

3. The method according to claim 1, wherein The ammonia-containing solution produced by washing with the acidic ammonium sulfate solution and acidic water washing solution of ammonia desulfurization is returned to the desulfurization system or decarbonization system.

4. The method according to claim 1, wherein At least one layer of liquid distributor is set up for the acidic ammonium sulfate liquid washing in ammonia-based desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system.

5. The method according to claim 1, wherein At least one layer of liquid distributor is set up for the acidic water washing of ammonia desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system or decarbonization system.

6. The method according to claim 2, wherein At least one layer of liquid distributor is set up for process water washing, and the generated ammonia solution is returned to the desulfurization system or decarbonization system.

7. The method according to claim 1, wherein Between the acidic ammonium sulfate solution and the acidic water washing solution used in ammonia desulfurization, there is a device or component that only allows gas to pass through.

8. The method according to claim 2, wherein Between the acidic ammonium sulfate solution used for ammonia desulfurization and the process water for washing, there are devices or components that only allow gas to pass through.

9. The method according to claim 1, wherein The ammonia decarbonization absorption cycle includes multiple stages of absorption, in which less or no ammonia is added in the last stage to reduce NH3 escape after decarbonization.

10. The method according to claim 1, wherein The NH3 content in the gas after treatment in the ammonia decarbonization functional zone absorption cycle section is 200 to 2000 ppm; preferably 400 to 1500 ppm; more preferably 500 to 1000 ppm.

11. The method according to claim 1, wherein After being treated in the ammonia slip control functional zone, the NH3 content in the gas is 0 to 30 ppm; preferably 0 to 20 ppm; more preferably 0 to 10 ppm.

12. The method according to claim 1, wherein The acidic ammonium sulfate solution has a pH of 4.5-6.5 and an ammonium sulfate concentration of 10-38 wt %; the acidic water wash solution has a pH of 3-7 and an ammonium sulfate concentration of 0-5 wt %.

13. The method according to claim 1, wherein The temperature of the acidic ammonium sulfate solution and the acidic water washing solution is 20-60°C, preferably 30-50°C.

14. The method according to claim 1, wherein Acidic ammonium sulfate solution and acidic water washing solution are cooled in a cooler before washing.

15. The method according to claim 2, wherein The liquid-to-gas ratio of process water is usually 5-25, preferably 10-20, and more preferably 12-18.

16. The method according to claim 1, wherein The liquid-to-gas ratio of the acidic ammonium sulfate solution is usually 1-20, preferably 1-10, and more preferably 2-6.

17. The method according to claim 1, wherein The liquid-to-gas ratio of the acidic water wash solution is usually 1-15, preferably 1-8, more preferably 2-5.

18. The method according to claim 1, wherein A gas-liquid contact component is provided in the acidic ammonium sulfate solution and acidic water washing liquid scrubber, and the gas-liquid contact component is preferably a filler.

19. The method according to claim 2, wherein The pH of process water, washing condensate and acidic water wash drainage shall not exceed 8.

20. The method according to claim 2, wherein Acid is added to process water, wash condensate, and acidic water wash water to adjust the pH. Preferably, the acid is sulfuric acid.

21. A device for controlling ammonia escape in an ammonia-based desulfurization and decarbonization system, characterized in that: Including ammonia desulfurization functional area, ammonia decarbonization functional area, ammonia escape control functional area, in, The ammonia desulfurization functional area includes the washing and cooling section, the absorption circulation section, and the particulate matter control section. The ammonia decarbonization functional area includes the cooling section and the absorption circulation section. The ammonia escape control functional area includes the ammonia escape control section, including the acidic ammonium sulfate washing system and the acidic water washing system. The absorption circulation section of the ammonia desulfurization functional area is connected to the acidic ammonium sulfate liquid washing system of the ammonia escape control functional area through a pipeline, and the particulate matter control section of the ammonia desulfurization functional area or the cooling section of the ammonia decarbonization functional area is connected to the acidic water washing system of the ammonia escape control functional area through a pipeline.

22. The device according to claim 21, wherein The ammonia decarbonization absorption cycle includes multiple stages of absorption, in which less or no ammonia is added in the last stage to reduce NH3 escape after decarbonization.

23. The device according to claim 21, wherein The ammonia escape control functional area may also include a process water washing system, which is connected to the process water pipe through a pipeline and is connected to the absorption circulation section of the ammonia desulfurization device or the absorption circulation section of the ammonia decarbonization device.

24. The device according to claim 21, wherein The sections of the ammonia desulfurization functional area and the ammonia decarbonization functional area can be combined into one tower or multiple towers, and equipment / components allowing gas to pass through are provided between the sections.

25. The device according to claim 21, wherein The particulate matter control section of the ammonia desulfurization functional area can partially or completely realize the function of the cooling section of the ammonia decarbonization functional area.