Apparatus and method for controlling ammonia leakage in an ammonia-based decarbonation system

Abstract

An apparatus and method for controlling ammonia leakage in an ammonia-based decarbonation system, in which ammonia may be used as a desulfurization and decarbonation agent, the gas may first enter a desulfurization device for desulfurization to produce ammonium sulfate fertilizer, and the desulfurized gas may enter a decarbonation device to remove carbon dioxide in the gas and produce ammonium bicarbonate fertilizer. The decarbonated gas may contain free ammonia, and the free ammonia in the gas may be absorbed with the acidic ammonium sulfate solution and acidic water wash of the ammonia-based desulfurization.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of Chinese Patent Application No. 202210552210.6, filed on May 19, 2022, which is incorporated herein by reference in its entirety. The present invention belongs to the technical field of environmental protection, and in particular to an apparatus and method for controlling ammonia leakage in an ammonia-based desulfurization and decarbonation system. [Background technology]

[0002] In recent years, the greenhouse effect has gradually become one of the most serious problems facing human beings. Carbon dioxide is the most important greenhouse gas, and the use of fossil energy is its main source of emissions. China's total CO 2 China's carbon emissions rank first in the world. Moreover, the situation that China's energy structure is dominated by coal will continue for some time. Coal energy will still be the basis of the new energy peak and energy security. China has committed to the world to reach its carbon peak in 2030 and achieve carbon neutrality in 2060. CO in exhaust flue gas 2 The capture, storage and resource utilization of greenhouse gases are of great importance for controlling and reducing greenhouse gas emissions and for combating the greenhouse effect and global warming.

[0003] At present, the carbon capture technology mainly used in the world is the organic amine method, but this method has problems such as high operating costs and large discharge of three wastes in the system. New decarbonation technologies are being actively researched at home and abroad. Compared with the organic amine method, the ammonia method has the advantages of easy regeneration, low operating costs, and the by-product of decarbonation is the important ammonium bicarbonate fertilizer. Ammonium bicarbonate is a nitrogen fertilizer and CO 2 It is a typical compound fertilizer that can simultaneously supply plants with CO. It is particularly suited to the needs of modern agriculture with soilless cultivation and greenhouse plant growth. 2resource use, carbon cycle, and CO2 reductions that may be caused by underground carbon storage 2 Environmental accidents can be avoided. Compared with organic amine decarboxylation products, ammonia has a high CO 2 It has an absorption efficiency and ammonium bicarbonate is easier to regenerate, which can greatly reduce the cost of decarbonation.

[0004] Ammonia-based decarbonation technology has always been the focus of research and is also the best way to solve greenhouse gases, but ammonia is volatile and decarbonation needs to be carried out under alkaline conditions, which leads to increased ammonia leakage. If this problem is not solved, a large amount of ammonia will leak, which not only increases the cost of decarbonation, but also causes secondary pollution.

[0005] China Patent Publication No. 113262625 proposes an integrated device for desulfurization and decarbonation, in which a part of the free ammonia in the process gas is reduced using a desulfurization circulation liquid for washing, and the washing liquid is returned to the desulfurization tower to be used as an absorbent for desulfurization. For the free ammonia in the process gas, even if the desulfurization circulation liquid is simply used for washing, a large amount of ammonia leakage may still occur. After washing with the desulfurization circulation solution and then washing with process water, a large amount of ammonia-containing solution is generated. If the ammonia-containing solution is returned to the desulfurization function zone to be used as an absorbent for desulfurization, the water balance of the desulfurization system may be disturbed and wastewater may be generated.

[0006] Chinese Patent No. 101600489 is for the prevention of SO from flue gas 2 The present paper proposes a method for acid washing ammonia using a cooling liquid, in which the process gas is cooled by using a cooling liquid, and sulfur dioxide in the process gas is absorbed in the cooling liquid, thereby obtaining a cooling liquid containing sulfate. Ammonia can be produced by contacting a process gas containing ammonia with a cooling liquid containing sulfate, and then absorbing the sulfur dioxide in the cooling liquid. 2It is removed from the process gas treated in the absorber. After the coolant absorbs sulfur dioxide, the main product produced should be sulfite. To achieve the effect of removing ammonia, sulfuric acid is added to the coolant to control the pH value of the coolant, which greatly increases the difficulty of controlling the device. In addition, this patent does not consider the material balance of desulfurization and decarbonation as a whole system, and only partial removal of sulfur dioxide is performed to obtain sulfate.

[0007] Therefore, it is desirable to provide an apparatus and method for controlling ammonia leakage in an ammonia-based decarbonation system, in which ammonia is used as a desulfurization and decarbonation agent, the gas first enters a desulfurization unit for desulfurization, and the desulfurized gas enters a decarbonation unit to remove carbon dioxide in the gas. The decarbonated gas contains free ammonia, and the free ammonia in the gas is absorbed by the acidic ammonium sulfate solution and acidic water wash of the ammonia-based desulfurization.

[0008] It is therefore desirable to control ammonia leakage in an ammonia-based decarbonation system while also using the ammonia recovered by scrubbing for desulfurization to conserve ammonia consumption. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] China Patent Application Publication No. 113262625 [Patent Document 2] China Patent No. 101600489 Summary of the Invention

[0010] An apparatus and method for controlling ammonia breakthrough in an ammonia-based decarbonation system is provided. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 shows a first embodiment. [Diagram 2] FIG. 2 shows a second embodiment. [Diagram 3] FIG. 3 shows a comparative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The method may include receiving a gas from an ammonia-based decarbonation process, the gas including free ammonia. The method may include receiving an acidic ammonium sulfate solution from an ammonia-based desulfurization process. The method may include receiving an acidic water wash from the ammonia-based desulfurization process. The method may include absorbing the free ammonia from the gas by scrubbing the gas with an acidic ammonium sulfate solution. The method may include absorbing the free ammonia from the gas by scrubbing the gas with an acidic water wash.

[0013] The absorption may be a first absorption. The method may include a second absorption of the free ammonia from the gas. The second absorption may occur prior to the first absorption. The second absorption may include washing the gas with process water including demineralized water, wash condensate and effluent of acid water wash.

[0014] The method may include using at least one layer of liquid distributor to cause contact of the acidic ammonium sulfate solution with the gas in the scrubbing. The method may include recovering the acidic ammonium sulfate solution after contact of the acidic ammonium sulfate solution with the gas. The method may include returning the recovered acidic ammonium sulfate solution to the desulfurization process. The method may include using at least one layer of liquid distributor to cause contact of the acidic water wash with the gas in the scrubbing. The method may include recovering the acidic water wash after contact of the acidic water wash with the gas. The method may include returning the recovered acidic water wash to the desulfurization process.

[0015] The method may include using at least one layer of liquid distributor to cause contact of the acidic ammonium sulfate solution with the gas in the scrubbing. The method may include recovering the acidic ammonium sulfate solution after contact of the acidic ammonium sulfate solution with the gas. The method may include returning the recovered acidic ammonium sulfate solution to the desulfurization process. The method may include using at least one layer of liquid distributor to cause contact of the acidic water wash with the gas in the scrubbing. The method may include recovering the acidic water wash after contact of the acidic water wash with the gas. The method may include returning the recovered acidic water wash to the decarbonation system.

[0016] The method may include scrubbing the gas with process water in the second absorption using at least one liquid distributor.The method may include returning the ammonia-containing solution produced in the second absorption to the desulfurization process.

[0017] The method may include providing at least one layer of a liquid distributor for washing with process water, the washing with process water producing an ammonia-containing solution. The method may include conveying the ammonia-containing solution to a decarbonation system.

[0018] The method may include providing a provision for passing only gas between the acidic ammonium sulfate solution wash and the acidic water wash.

[0019] The method may include providing a gas-only passing component between the acidic ammonium sulfate solution wash and the acidic water wash.

[0020] The method may include providing a gas-only passage provision between the acidic ammonium sulfate solution wash and the process water wash.

[0021] The method may include providing a gas-only passing component between the acidic ammonium sulfate solution wash and the process water wash.

[0022] The ammonia-based decarbonation process may include multiple absorption stages, including a final stage, in which less ammonia is added to the final stage than in the previous stage, and NH 3 Reduce leakage to 200-2000ppm.

[0023] After being processed in the absorption and recycle section of the ammonia decarbonation zone, the gas has a NH 3 The gas after being treated in the ammonia leakage control zone may have an NH 3 It may have a content.

[0024] The acidic ammonium sulfate solution may have a pH in the range of 4.5 to 6.5. The acidic ammonium sulfate solution may have an ammonium sulfate concentration in the range of 10 to 38 wt% (weight percent). The acidic water cleaning solution may have a pH in the range of 3 to 7. The acidic water cleaning solution may have an ammonium sulfate concentration in the range of 0 to 5 wt%.

[0025] The acidic ammonium sulfate solution and the acidic water washing solution may have a temperature in the range of 20 to 60°C, and the acidic ammonium sulfate solution and the acidic water washing solution are cooled by a cooler before washing.

[0026] The liquid-gas ratio for cleaning with process water may be in the range of 5 to 25. The liquid-gas ratio for cleaning with an acidic ammonium sulfate solution may be in the range of 1 to 20. The liquid-gas ratio for cleaning with an acidic water cleaning solution may be in the range of 1 to 15.

[0027] The method may include providing a first gas-liquid contacting component for scrubbing with an acidic ammonium sulfate solution.The method may include providing a second gas-liquid contacting component for scrubbing with an acidic water scrubbing solution.

[0028] One or more of the process water, wash condensate and acid water wash effluent may have a pH of 8 or less.

[0029] The method may include adding acid to the process water, wash condensate and acidic wash effluent to adjust the pH.

[0030] The apparatus may include equipment for controlling ammonia breakthrough in an ammonia-based desulfurization and decarbonation system.

[0031] The apparatus may include an ammonia-based desulfurization zone.The apparatus may include an ammonia-based decarbonation zone.The apparatus may include an ammonia breakthrough control zone.

[0032] The ammonia-based desulfurization zone may include a scrubbing and cooling section.The ammonia-based desulfurization zone may include an absorption recycle section.The ammonia-based desulfurization zone may include a particle control section.

[0033] The ammonia-based decarbonation zone may include a cooling section.The ammonia-based decarbonation zone may include an absorption recycle section.

[0034] The ammonia leak control zone may include an ammonia leak control section. The ammonia leak control section may include an acidic ammonium sulfate solution washing system. The ammonia leak control section may include an acid water wash system.

[0035] The absorption circulation section of the ammonia-based desulfurization zone may be connected via a pipe to an acidic ammonium sulfate solution wash system of the ammonia breakthrough control zone. The particle control section of the ammonia-based desulfurization zone may be connected via a pipe to an acidic water wash system of the ammonia breakthrough control zone.

[0036] The absorption recycle section of the ammonia-based decarbonation zone may include multiple absorption stages, including a final stage, which may be configured to add less ammonia than the previous stage.

[0037] The final step is NH after decarboxylation. 3 It may be configured to reduce leakage to between 200 and 2000 ppm.

[0038] The ammonia breakthrough control zone may include a process water wash system. The process water wash system may be connected via a pipe to the process water line. The process water wash system may be connected to the absorption recycle section of the ammonia-based desulfurization unit.

[0039] The ammonia breakthrough control zone may include a process water wash system. The process water wash system may be connected via piping to the process water line. The process water wash system may be connected to the absorption recycle section of the ammonia-based decarbonation unit.

[0040] The apparatus may include one or more columns. The apparatus may include a device configured to pass only gas.

[0041] The ammonia-based desulfurization zone and the ammonia-based decarbonation zone sections may be configured to be combined into one or more towers, and equipment may be provided between the sections.

[0042] The particle control section of the ammonia-based desulfurization zone may be configured to provide the cooling provided by the cooling section of the ammonia-based decarbonation zone.

[0043] The apparatus may include an ammonia-based desulfurization zone.The apparatus may include an ammonia-based decarbonation zone.The apparatus may include an ammonia breakthrough control zone.

[0044] The ammonia-based desulfurization zone may include. The ammonia-based desulfurization zone may include a scrubbing and cooling section. The ammonia-based desulfurization zone may include an absorption circulation section. The ammonia-based desulfurization zone may include a particle control section.

[0045] The ammonia-based decarbonation zone may include a cooling section.The ammonia-based decarbonation zone may include an absorption recycle section.

[0046] The ammonia leak control zone may include an ammonia leak control section. The ammonia leak control section may include an acidic ammonium sulfate solution wash system. The ammonia leak control section may include an acidic water wash system.

[0047] The absorption recycle section of the ammonia-based desulfurization zone may be connected via piping to an acidic ammonium sulfate solution wash system of the ammonia breakthrough control zone.

[0048] The cooling section of the ammonia-based decarbonation zone may be connected via piping to the acid water wash system of the ammonia breakthrough control zone.

[0049] The absorption recycle section of the ammonia-based decarbonation zone may include multiple absorption stages, including a final stage. The final stage may be configured to add less ammonia than the previous stage. The final stage may add NH 3 It may be configured to reduce leakage to between 200 and 2000 ppm.

[0050] The ammonia breakthrough control zone may include a process water wash system. The process water wash system may be connected via a pipe to the process water line. The process water wash system may be connected to the absorption recycle section of the ammonia-based desulfurization zone.

[0051] The ammonia breakthrough control zone may include a process water wash system. The process water wash system may be connected via piping to the process water line. The process water wash system may be connected to the absorption recycle section of the ammonia-based decarbonation unit.

[0052] The apparatus may include one or more columns. The apparatus may include a facility configured to allow only gas to pass through.

[0053] The ammonia-based desulfurization zone and the ammonia-based decarbonation zone sections may be configured to be combined into one or more towers, and equipment may be provided between the sections.

[0054] The particle control section of the ammonia-based desulfurization zone may be configured to provide the cooling provided by the cooling section of the ammonia-based decarbonation zone.

[0055] The apparatus and method may include controlling ammonia leakage within an ammonia-based decarbonation system, where the ammonia is used to reduce sulfur oxides and CO 2 and may be employed to produce ammonium sulfate fertilizer and ammonium bicarbonate fertilizer. The ammonia-based desulfurization and decarbonation device may include an ammonia-based desulfurization functional zone, an ammonia-based decarbonation functional zone, and an ammonia leakage control functional zone. The ammonia-based desulfurization functional zone may include a cleaning and cooling section, an absorption circulation section, and a particle control section. The ammonia-based decarbonation functional zone may include a cooling section and an absorption circulation section. The ammonia leakage control functional zone may include an acidic ammonium sulfate solution cleaning system and an acidic water cleaning system. The absorption circulation section of the ammonia-based desulfurization functional zone may be connected to the acidic ammonium sulfate solution cleaning system of the ammonia leakage control functional zone via a pipe, and the particle control section of the ammonia-based desulfurization functional zone or the cooling section of the ammonia-based decarbonation functional zone may be connected to the acidic water cleaning system of the ammonia leakage control functional zone via a pipe. The ammonia-based decarbonation absorption circulation section is configured to purify the NH 2 after decarbonation. 3To reduce leakage, multiple absorption stages may be provided with little or no ammonia added in the final stage.

[0056] Ammonia may be used as a desulfurization and decarbonation agent. The gas may first enter a desulfurization functional zone for desulfurization to produce ammonium sulfate fertilizer. The desulfurized gas may enter a decarbonation functional zone to remove carbon dioxide in the gas and produce ammonium bicarbonate fertilizer. The decarbonated gas may contain free ammonia, and may be washed with an acidic ammonium sulfate solution of ammonia-based desulfurization and an acidic water washing solution to absorb the free ammonia in the gas. The acidic ammonium sulfate solution may include a solution of the absorption circulation section of the ammonia-based desulfurization functional zone, the ammonium sulfate concentration of which may be in the range of 10 to 38% by weight, and the pH of which may be in the range of 4.5 to 6.5. The acidic water washing solution may include a solution of the particle control section of the ammonia-based desulfurization functional zone or a solution of the cooling section of the ammonia-based decarbonation functional zone, the ammonium sulfate concentration of which may be in the range of 0 to 5% by weight, and the pH of which may be in the range of 3 to 7. After cleaning in the ammonia leakage control functional zone, the concentrations of the acidic ammonium sulfate solution and the acidic water cleaning solution may be essentially unchanged, the pH of the acidic ammonium sulfate solution may be in the range of 4.6 to 6.9, and the pH of the acidic water cleaning solution may be in the range of 3.5 to 7.5.

[0057] The temperature of the acidic ammonium sulfate solution and the acidic water washing solution may be in the range of 20 to 60°C, preferably 30 to 50°C.

[0058] Prior to washing, the acidic ammonium sulfate solution and the acidic water washing solution may be cooled by a cooler before washing.

[0059] A liquid distributor and a gas-liquid contact section may be provided inside the scrubber for the acidic ammonium sulfate solution and the acidic water scrubber. The liquid distributor may include a trough distributor, and the gas-liquid contact section may include a packing.

[0060] This may include scrubbing the gas with process water to absorb the free ammonia prior to using the acidic ammonium sulfate solution and acidic water wash of the ammonia-based desulfurization to absorb the free ammonia in the gas. The process water may include demineralized water or solution in the cooling section of the ammonia-based decarbonation functional zone, or the effluent of the acidic water wash system of the ammonia breakthrough control functional zone.

[0061] At least one liquid distributor may be provided for washing with an acidic ammonium sulfate solution for ammonia-based desulfurization, and the solution after gas-liquid contact washing may be recovered and returned to the desulfurization system.

[0062] At least one liquid distributor may be provided for washing with the acidic water washing solution of the ammonia-based desulfurization, and the solution after the gas-liquid contact washing may be recovered and returned to the desulfurization system or the decarbonation system.

[0063] At least one liquid distributor may be provided for washing with process water and the produced ammonia-containing solution may be returned to the desulfurization or decarbonation system.

[0064] A liquid collector that allows only gas to pass through may be provided between the washing with the acidic ammonium sulfate solution of the ammonia-based desulfurization and the washing with the acidic water washing solution.

[0065] Between the acidic ammonium sulfate solution wash of the ammonia-based desulfurization and the process water wash, a liquid collector that allows only gas to pass through may be provided.

[0066] The above functional zones may be combined in one tower or in several towers. In the desulfurization functional zone, at least one spray bed may be provided in each section, and equipment / components through which gas passes may be provided between the sections. The particle removal section may be divided into two parts. The spray cleaning in the first part may include circulating cleaning with a high-concentration solution containing ammonium sulfate, and the spray cleaning in the second part may include circulating cleaning with a dilute solution containing ammonium sulfate. Equipment / components through which gas passes may be present between the two parts. In the decarbonation functional zone, at least one spray bed may be provided in each section, and equipment / components through which gas passes may be provided between the sections.

[0067] The ammonia-based decarbonated gas may include free ammonia. The apparatus and method may include the use of an ammonia-based desulfurization acidic ammonium sulfate solution and an acidic water wash to scrub the ammonia-based decarbonated gas to absorb the free ammonia therein. The apparatus and method may include scrubbing with process water to absorb the free ammonia prior to using the ammonia-based desulfurization acidic ammonium sulfate solution and an acidic water wash to absorb the free ammonia in the gas. The process water may include demineralized water and wash condensate.

[0068] In the present apparatus and method, the flow rate of the acidic ammonium sulfate solution, the acidic water cleaning solution, or the process water used for cleaning and absorption may be adjusted as necessary, and the liquid-gas ratio of the process water may be in the range of 5 to 25, 10 to 20, or 12 to 18, the liquid-gas ratio of the acidic ammonium sulfate solution may be in the range of 1 to 20, 1 to 10, or 2 to 6, and the liquid-gas ratio of the acidic water cleaning solution may be in the range of 1 to 20, 1 to 15, or 2 to 10. Liquid to gas ratio = Q / V Here, Q is the liquid circulation rate (L / h), V is the process gas flow rate after ammonia decarbonation (the gas flow rate under the working conditions, i.e., the operating conditions (temperature, pressure, etc.)) (m 3 / h).

[0069] The present device and method can mainly remove free ammonia contained in the gas after ammonia-based decarbonation, and can also remove SO 2 Content and CO 2 It has almost no effect on the content.

[0070] For the acidic ammonium sulfate solution, the pH may be in the range of 4.5 to 6.5, and the ammonium sulfate concentration may be in the range of 10 to 38% by weight, 12 to 35% by weight, 15 to 30% by weight, or 17 to 28% by weight. For the acidic water cleaning solution, the pH may be in the range of 3 to 7, and the ammonium sulfate concentration may be in the range of 0 to 5% by weight, 0 to 3% by weight, 0 to 1% by weight, or 0 to 0.6% by weight.

[0071] In the method of the present invention, the temperature of the acidic ammonium sulfate solution and the acidic water washing solution may be in the range of 20 to 60°C or in the range of 30 to 50°C.

[0072] NH in the gas after being treated by the decarbonation absorption tower 3 The content may be in the range of 200 to 2000 ppm, in the range of 400 to 1500 ppm, or in the range of 500 to 1000 ppm.

[0073] SO in gas after treatment by the decarbonation absorption tower 2 The content is 0-20mg / Nm 3 Range: 0-15mg / Nm 3 or 0 to 10 mg / Nm 3 may be in the range.

[0074] CO in gas after being treated by the decarbonation absorption tower 2 The content may be in the range of 0 to 20v% (volume percent), in the range of 1 to 10v%, or in the range of 2 to 7v%.

[0075] NH in the gas after treatment 3 The content may be in the range of 0 to 30 ppm, in the range of 0 to 20 ppm, or in the range of 0 to 10 ppm.

[0076] The present apparatus and methods may provide beneficial economic effects in addition to technical effects, such as reduced ammonia leakage, reduced ammonia consumption, and reduced ammonia consumption losses by 96% to 99% or 97% to 99%, as shown in the examples below.

[0077] In the present invention, the SO 2 The content can be tested according to HJ 629-2011 Fixed Pollution Source Waste Gas-Determination of Sulfur Dioxide-Non-Dispersive Infrared Absorption Method, and CO 2 The content can be tested according to HJ 870-2017 Fixed Pollution Source Waste Gas-Determination of Carbon Dioxide-Non-Dispersive Infrared Absorption Method, NH 3 The content can be tested according to HJ 533-2009 Ambient Air and Waste Gas-Determination of Ammonia-Nesseler's Reagent Spectroscopic Analysis.

[0078] All concentrations referred to in this invention are by weight unless otherwise specified.

[0079] Exemplary embodiments of apparatus and methods according to the principles of the present invention will now be described with reference to the accompanying drawings, which form a part hereof. It is to be understood that other embodiments may be utilized, structural, functional and procedural modifications, additions or omissions may be made, and features of the exemplary embodiments, whether apparatus or methods, may be combined without departing from the scope and spirit of the invention.

[0080] FIG. 1 shows an illustrative example 1 in which the gas was scrubbed with process water to absorb free ammonia prior to using an acidic ammonium sulfate solution and an acidic water wash of ammonia-based desulfurization to absorb the free ammonia in the gas.

[0081] FIG. 2 shows an illustrative example 2 in which an acidic ammonium sulfate solution of ammonia-based desulfurization and an acidic water wash were used to scrub the gas and absorb the free ammonia therein.

[0082] FIG. 3 shows an exemplary comparative example where the gas was scrubbed with process water to absorb the free ammonia.

[0083] Illustrative Example 1 As shown in Figure 1, sulfur oxides and CO 2 The process gas 1 containing the above-mentioned enters the desulfurization function zone 2 and passes through the desulfurization cleaning cooling section 2-1, the desulfurization absorption circulation section 2-2, and the desulfurization particle control section 2-3 in this order. In the desulfurization cleaning cooling section 2-1, the desulfurization circulation pump a3 is used to perform spray circulation, and the ammonium sulfate solution is concentrated while cooling the exhaust gas, and the concentrated ammonium sulfate slurry with the solids precipitated is sent to the ammonium sulfate production 26 via the ammonium sulfate discharge pump 9. The desulfurization circulation pump b4, the desulfurization circulation pump c5, and the desulfurization circulation tank 6 are used to perform absorption spray circulation, and the sulfur oxides (sulfur dioxide and sulfur trioxide) in the exhaust gas are absorbed. The desulfurization circulation pump c5 cooled a part of the ammonium sulfate solution 20 to 35 ° C. by the cooler 32, and then sent it to the ammonium sulfate washing section 18-2 of the ammonia washing tower, and returned the washed solution 21 to the desulfurization circulation tank 6. The desulfurization circulation pump d10 was used to perform cleaning spray circulation, and the desulfurization heat exchanger 11 was used to control the cleaning temperature and the temperature of the exhaust gas 12 after desulfurization. The particle control section 2-3 of the ammonia-based desulfurization functional zone performed the cooling function of the ammonia-based decarbonation. The acid solution 23 condensed from the flue gas was cooled to 35°C by the cooler 33 and then used as makeup water for the acid water washing section 18-3 of the ammonia washing tower, and the washing liquid 24 was returned to the desulfurization circulation tank 6. It went to the desulfurization system 8 for ammonia addition, and after metering, it went to the desulfurization circulation tank 6 for ammonia addition. The oxidation air 7 went to the desulfurization circulation tank 6 to oxidize the solution.

[0084] The desulfurized exhaust gas 12 enters the decarbonation absorption tower 13, where it is absorbed and circulated using the decarbonation circulation pump 14, and the final product, ammonium carbonate 27, is pumped out using the ammonium hydrogen carbonate discharge pump 15. It is sent to the decarbonation system 16 for ammonia addition, and after metering, it is sent to the decarbonation absorption tower 13 for ammonia addition.

[0085] The decarbonated exhaust gas 17 entered the ammonia washing tower 18 and passed through the process water washing section 18-1, the ammonium sulfate washing section 18-2 and the acid water washing section 18-3 in this order. In the process water washing section 18-1 of the ammonia washing tower, process water washing was performed using the ammonia washing circulation pump a19, the process water washing section 18-1 of the ammonia washing tower was provided with a trough distributor 31-1 and a packing 30-1, process water was replenished through an external process water pipe 28, and the ammonia-containing solution 29 after washing was sent to the decarbonation tower 13. A part of the ammonium sulfate solution 20 in the desulfurization absorption section sent by the desulfurization circulation pump c5 entered the ammonium sulfate washing section 18-2 of the ammonia washing tower, the ammonium sulfate washing section 18-2 of the ammonia washing tower was provided with a trough distributor 31-2 and a packing 30-2, and the washed solution (i.e., the return desulfurization solution) 21 was returned to the desulfurization circulation tank 6. The acid solution (i.e., the solution in the desulfurization fine particle control section) 23 concentrated from the flue gas sent out by the desulfurization circulation pump d10 was used as makeup water for the acid water washing section 18-3 of the ammonia washing tower, which was provided with a trough distributor 31-3 and packing 30-3, and the washed solution (i.e., the return acid solution) 24 was returned to the desulfurization circulation tank 6. After washing, the cleaned flue gas 25 was discharged.

[0086] The flow rate of the acidic ammonium sulfate solution 20 is 350m 3 / h, pH was 6.4, and ammonium sulfate concentration was 18 wt%. The acidic ammonium sulfate solution returned after entering the ammonia wash tower had a pH of 6.9 and its ammonium sulfate concentration was essentially unchanged.

[0087] The flow rate of the acid water washing solution 23 was adjusted according to the pH value of the water washing solution in the acid water washing section 18-3 of the ammonia washing tower, whose pH was 3.8 and whose ammonium sulfate concentration was 2 wt%. The acid water washing solution returned after entering the ammonia washing tower had a pH of 4.2 and its ammonium sulfate concentration was basically unchanged. The circulation volume of the ammonia washing circulation pump b22 was 500 m 3 / h.

[0088] The flow rate of the 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, and the circulation volume of the ammonia washing circulation pump a19 is adjusted to 1200 m 3 / h. The pH of the demineralized water was selected to be 6.9, and the pH of the returned solution after entering the ammonia wash tower was 7.9.

[0089] 99.6% anhydrous ammonia is selected as the absorbent for desulfurization and decarbonation, and the parameters of process gas 1 are shown in the table below.

[0090] [Table 1]

[0091] The parameters of the gas 12 after desulfurization and cooling are given in the table below.

[0092] [Table 2]

[0093] The main parameters of the gas 17 treated by the decarbonation absorption tower are shown in the table below.

[0094] [Table 3]

[0095] The main parameters of the gas 25 after being treated by the ammonia scrubber are given in the table below.

[0096] [Table 4]

[0097] The ammonia leakage amount is 4.98t / year, and the ammonia consumption loss is about 20,000 yuan / year.

[0098] Illustrative Example 2 As shown in Figure 2, the exemplary embodiment 2 is similar to the exemplary embodiment 1, except that the process water washing section 18-1 of the ammonia wash tower is not provided. The parameters of desulfurization and decarbonation are the same, and the main parameters of the gas 25 after treatment in the ammonia wash tower are shown in the following table.

[0099] [Table 5]

[0100] The amount of ammonia leakage is 8.96t / year, and the ammonia consumption loss is about 36,000 yuan / year.

[0101] Illustrative Comparative Examples As shown in Figure 3, the exemplary comparative example is the same as the exemplary embodiment 1, except that the ammonium sulfate washing section 18-2 and the acidic solution water washing section 18-3 of the ammonia washing tower are not provided. The parameters of desulfurization and decarbonation are the same, and the main parameters of the gas 25 after treatment in the ammonia washing tower are shown in the following table.

[0102] [Table 6]

[0103] The amount of ammonia leakage is 248t / year, and the ammonia consumption loss is about 99,2000 yuan / year.

[0104] From a comparison of the above exemplary examples and the exemplary comparative examples, it can be seen that the amount of ammonia leakage in the gas treated by the method and apparatus of the present invention is significantly reduced, resulting in a significant reduction in ammonia consumption loss.

[0105] Exemplary features may include the following: 1. A method for controlling ammonia leakage in an ammonia-based decarbonation system, in which the gas after ammonia-based decarbonation contains free ammonia, and the gas after ammonia-based decarbonation is scrubbed with an acidic ammonium sulfate solution of ammonia-based desulfurization and an acidic water scrubber to absorb the free ammonia therein.

[0106] 2. The method of embodiment 1, wherein prior to absorbing the free ammonia in the gas with the acidic ammonium sulfate solution and acidic water wash of ammonia-based desulfurization, the method further comprises scrubbing the gas with process water to absorb the free ammonia, the process water being preferably demineralized water, wash condensate, and effluent of the acidic water wash.

[0107] 3. The method of embodiment 1, wherein the ammonia-containing solution produced by washing with the acidic ammonium sulfate solution and acidic water wash of the ammonia-based desulfurization is returned to the desulfurization or decarbonation system.

[0108] 4. The method according to embodiment 1, wherein at least one liquid distributor is provided for washing with an acidic ammonium sulfate solution of ammonia-based desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system.

[0109] 5. The method according to embodiment 1, wherein at least one liquid distributor is provided for washing with an acidic water washing solution of ammonia-based desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system or decarbonation system.

[0110] 6. The method according to aspect 2, wherein at least one liquid distributor is provided for washing with process water, and the produced ammonia-containing solution is returned to the desulfurization or decarbonation system.

[0111] 7. The method of embodiment 1, wherein equipment or components are provided that allow only gas to pass during the scrubbing with the acidic ammonium sulfate solution and acidic water scrubbing of the ammonia-based desulfurization.

[0112] 8. The method of embodiment 2, wherein equipment or components that allow only gas to pass are provided between the acidic ammonium sulfate solution wash of the ammonia-based desulfurization and the process water wash.

[0113] 9. The ammonia decarbonation absorption circulation section is equipped with multi-stage absorption, and in the final stage, the NH after decarbonation is circulated with little or no ammonia added. 3 The method of embodiment 1, wherein leakage is reduced.

[0114] 10. NH in the gas after it has been treated in the absorption circulation section of the ammonia decarbonation function zone 3 The method according to aspect 1, wherein the content is 200 to 2000 ppm, preferably 400 to 1500 ppm, and more preferably 500 to 1000 ppm.

[0115] 11. NH in the gas after being treated in the ammonia leakage control function zone 3 The method according to aspect 1, wherein the content is 0 to 30 ppm, preferably 0 to 20 ppm, and more preferably 0 to 10 ppm.

[0116] 12. The method of 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.%, and the acidic water wash has a pH of 3-7 and an ammonium sulfate concentration of 0-5 wt.%.

[0117] 13. The method according to aspect 1, wherein the temperature of the acidic ammonium sulfate solution and the acidic water washing solution is 20 to 60°C, preferably 30 to 50°C.

[0118] 14. The method of claim 1, wherein the acidic ammonium sulfate solution and the acidic water wash are cooled by a cooler before washing and then washed.

[0119] 15. The method according to aspect 2, wherein the liquid-gas ratio of the process water is generally 5-25, preferably 10-20, and more preferably 12-18.

[0120] 16. The method according to aspect 1, wherein the liquid-gas ratio of the acidic ammonium sulfate solution is generally 1-20, preferably 1-10, and more preferably 2-6.

[0121] 17. The method according to aspect 1, wherein the liquid-gas ratio of the acidic water cleaning solution is generally 1-15, preferably 1-8, and more preferably 2-5.

[0122] 18. The method of claim 1, wherein a gas-liquid contacting component is provided in the scrubber of the acidic ammonium sulfate solution and the acidic water scrubber, and the gas-liquid contacting component is preferably a packing.

[0123] 19. The method of claim 2, wherein the pH of the process water, wash condensate and acid water wash effluent is 8 or less.

[0124] 20. The method of claim 2, wherein an acid is added to the process water, wash condensate and acid water wash effluent to adjust the pH, preferably the acid is sulfuric acid.

[0125] 21. An apparatus for controlling ammonia leakage in an ammonia-based desulfurization and decarbonation system, the apparatus comprising an ammonia-based desulfurization functional zone, an ammonia-based decarbonation functional zone, and an ammonia leakage control functional zone; The ammonia-based desulfurization functional zone comprises a scrubbing and cooling section, an absorption circulation section, and a particle control section; The ammonia decarbonation functional zone comprises a cooling section and an absorption circulation section; The ammonia leakage control functional zone comprises an ammonia leakage control section including an acidic ammonium sulfate solution washing system and an acidic water washing system; The absorption circulation section of the ammonia-based desulfurization functional zone is connected to the acidic ammonium sulfate solution washing system of the ammonia leakage control functional zone via a pipe, and the particle control section of the ammonia-based desulfurization functional zone or the cooling section of the ammonia-based decarbonation functional zone is connected to the acidic water washing system of the ammonia leakage control functional zone via a pipe, in this apparatus.

[0126] 22. The ammonia decarbonation absorption circulation section has multi-stage absorption, and in the final stage, the NH 3 22. The device of embodiment 21, which reduces leakage.

[0127] 23. The apparatus of embodiment 21, wherein the ammonia breakthrough control functional zone can also include a process water wash system, the process water wash system being connected to the process water pipe through a pipe and connected to the absorption circulation section of the ammonia-based desulfurization apparatus or the absorption circulation section of the ammonia-based decarbonation apparatus.

[0128] 24. The apparatus of embodiment 21, wherein the sections of the ammonia-based desulfurization functional zone and the ammonia-based decarbonation functional zone can be combined into one tower or multiple towers, with equipment / components provided between the sections that allow gas to pass through.

[0129] 25. The apparatus of embodiment 21, wherein the particle control section of the ammonia-based desulfurization functional zone can partially or completely realize the functions of the cooling section of the ammonia-based decarbonation functional zone.

[0130] All ranges and parameters disclosed herein are to be understood to encompass any and all subranges subsumed therein, all numbers between the endpoints, and the endpoints. For example, a range stated as "1 to 10" should be considered to include any and all subranges between (and including) the minimum value of 1 and the maximum value of 10, i.e., beginning with a minimum value of 1 or more (e.g., 1 to 6.1) and ending with a maximum value of 10 or less (e.g., 2.3 to 9.4, 3 to 8, 4 to 7), and ending with each of the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 included within the range.

[0131] Thus, an apparatus and method for controlling ammonia breakthrough in an ammonia-based decarbonation system has been provided. Those skilled in the art will appreciate that the invention may be practiced by other than the described embodiments, which are presented for purposes of illustration and not limitation. The invention is limited only by the scope of the following claims. [Explanation of symbols]

[0132] Process Gas 1 Desulfurization function zone 2 Desulfurization cleaning cooling section 2-1 Desulfurization absorption circulation section 2-2 Desulfurization Particle Control Section 2-3 Desulfurization Circulation Pump a3 Desulfurization Circulation Pump b4 Desulfurization Circulation Pump C5 Desulfurization circulation tank 6 Oxidizing Air 7 Addition of ammonia to the desulfurization system 8 Ammonium sulfate discharge pump 9 Desulfurization Circulation Pump d10 Desulfurization heat exchanger 11 Desulfurized exhaust gas 12 Decarbonation absorption tower 13 Decarbonation Circulation Pump 14 Ammonium bicarbonate discharge pump 15 Addition of ammonia to the decarbonation system 16 Decarbonated exhaust gas 17 Ammonia Wash Tower 18 Process Water Cleaning Section 18-1 Ammonium sulfate cleaning section 18-2 Acid Water Cleaning Section 18-3 Ammonia cleaning circulation pump a19 Ammonium sulfate solution in the desulfurization absorption section 20 Return desulfurization solution 21 Ammonia cleaning circulation pump b22 Desulfurization Particle Control Section Solution 23 Return acid solution 24 Clean flue gas 25 The final product is ammonium sulfate 26 The final product is ammonium bicarbonate 27 Process Water 28 Ammonia-containing solution 29 Process water washing section packing 30-1 Ammonium sulfate washing section filler 30-2 Acid water cleaning section filler 30-3 Trough distributor in process water washing section 31-1 Trough distributor 31-2 in ammonium sulfate washing section Trough distributor 31-3 in acid water washing section Ammonium sulfate solution heat exchanger in desulfurization absorption section to ammonia wash 32 Solution heat exchanger in desulfurization particle control section to ammonia wash 33

Claims

1. A method for controlling ammonia leakage in an ammonia-based decarbonation system, wherein the gas after ammonia-based decarbonation contains free ammonia, and the gas after ammonia-based decarbonation is scrubbed with an acidic ammonium sulfate solution of ammonia-based desulfurization and an acidic water scrub to absorb the free ammonia therein.

2. 2. The method according to claim 1, wherein prior to absorbing the free ammonia in the gas with the acidic ammonium sulfate solution and acidic water wash of the ammonia-based desulfurization, the method further comprises scrubbing the gas with process water to absorb free ammonia, the process water being preferably demineralized water, wash condensate and effluent of acidic water wash.

3. 2. The method of claim 1, wherein the ammonia-containing solution produced by the ammonia-based desulfurization acidic ammonium sulfate solution and acidic water wash is returned to the desulfurization or decarbonation system.

4. 2. The method according to claim 1, wherein at least one liquid distributor is provided for washing the ammonia-based desulfurization with an acidic ammonium sulfate solution, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system.

5. 2. The method according to claim 1, wherein at least one liquid distributor is provided for washing with the acidic water washing solution of the ammonia-based desulfurization, and the solution after gas-liquid contact washing is recovered and returned to the desulfurization system or decarbonation system.

6. 3. The method according to claim 2, wherein at least one liquid distributor is provided for washing with the process water and the produced ammonia-containing solution is returned to the desulfurization or decarbonation system.

7. 2. The method of claim 1, wherein equipment or components are provided that allow only gas to pass during the ammonia-based desulfurization acidic ammonium sulfate solution and acidic water washes.

8. 3. The method of claim 2, wherein equipment or components that allow only gas to pass are provided between the ammonia-based desulfurization acidic ammonium sulfate solution wash and the process water wash.

9. The ammonia-based decarbonation absorption circulation section is equipped with multi-stage absorption, and in the final stage, NH after decarbonation is circulated with little or no ammonia added. ３ The method of claim 1 , wherein leakage is reduced.

10. NH in the gas after being treated in the absorption circulation section of the ammonia-based decarbonation functional zone. ３ 2. The method according to claim 1, wherein the content is from 200 to 2000 ppm, preferably from 400 to 1500 ppm, more preferably from 500 to 1000 ppm.

11. NH in the gas after being treated in the ammonia leakage control function zone. ３ The method according to claim 1, wherein the content is from 0 to 30 ppm, preferably from 0 to 20 ppm, more preferably from 0 to 10 ppm.

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

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

14. 2. The method of claim 1, wherein the acidic ammonium sulfate solution and the acidic water wash are cooled by a chiller before washing and then washed.

15. The process according to claim 2, wherein the liquid to gas ratio of the process water is generally from 5 to 25, preferably from 10 to 20, more preferably from 12 to 18.

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

17. The method of claim 1, wherein the acidic water cleaning solution has a liquid-gas ratio of generally 1-15, preferably 1-8, and more preferably 2-5.

18. 2. The method according to claim 1, wherein a gas-liquid contacting component is provided in the scrubber of the acidic ammonium sulfate solution and the acidic water scrubber, the gas-liquid contacting component being preferably a packing.

19. 3. The method of claim 2, wherein the process water, the wash condensate and the acidic water wash effluent have a pH of 8 or less.

20. 3. The method of claim 2, wherein an acid is added to the process water, the wash condensate and the acidic water wash effluent to adjust the pH, preferably the acid is sulfuric acid.

21. An apparatus for controlling ammonia leakage in an ammonia-based desulfurization and decarbonation system, the apparatus comprising an ammonia-based desulfurization functional zone, an ammonia-based decarbonation functional zone, and an ammonia leakage control functional zone; The ammonia-based desulfurization functional zone comprises a scrubbing and cooling section, an absorption circulation section, and a particle control section; The ammonia-based decarbonation functional zone comprises a cooling section and an absorption circulation section; The ammonia leakage control functional zone comprises an ammonia leakage control section including an acidic ammonium sulfate solution washing system and an acidic water washing system; The absorption circulation section of the ammonia-based desulfurization functional zone is connected to the acidic ammonium sulfate solution washing system of the ammonia leakage control functional zone via a pipe, and the particle control section of the ammonia-based desulfurization functional zone or the cooling section of the ammonia-based decarbonation functional zone is connected to the acidic water washing system of the ammonia leakage control functional zone via a pipe.

22. The ammonia-based decarbonation absorption circulation section is equipped with multi-stage absorption, and in the final stage, NH after decarbonation is circulated with little or no ammonia added. ３ 22. The device of claim 21 which reduces leakage.

23. The ammonia breakthrough control functional zone may also include a process water wash system, the process water wash system is connected to a process water pipe through a pipe and to the absorption circulation section of the ammonia-based desulfurization apparatus or the absorption circulation section of the ammonia-based decarbonation apparatus according to claim 21.

24. 22. The apparatus of claim 21, wherein the sections of the ammonia-based desulfurization functional zone and the ammonia-based decarbonation functional zone can be combined into one tower or multiple towers, with equipment / components between the sections that allow gas to pass through.

25. 22. The apparatus of claim 21, wherein the particle control section of the ammonia-based desulfurization functional zone is capable of partially or completely fulfilling the function of the cooling section of the ammonia-based decarbonation functional zone.

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