Method and device for coupling electron beam irradiation with humic acid salt desulfurization and denitrification and co-production of slow-release fertilizer

Abstract

The application discloses a method and device for coupling electron beam irradiation with humic acid salt desulfurization and denitrification and co-production of slow-release fertilizer. First, flue gas containing SO2 and NO is subjected to electron beam irradiation in ammonia, and active free radicals generated are used to oxidize the flue gas into SO3 and NO2 and generate ammonium salt aerosol; then, a humic acid salt solution is used for absorption, and in-situ modification of humic acid is performed by free radicals to generate small-molecule fulvic acid; the ammonium salt aerosol is captured by absorption liquid foam to form a humic acid ammonium salt compound, and organic-inorganic composite slow-release fertilizer is obtained through drying. A gas curtain protection device and a liquid droplet interception net are arranged at an electron scanning window of an integrated reactor to form a double protection system. The application solves the problems of difficult capture, easy deliquescence and low utilization rate of by-products aerosol of the electron beam method and damage of the scanning window, realizes double utilization of electron beam energy and irradiation modification of sodium humate, the desulfurization efficiency is greater than or equal to 98%, the denitrification efficiency is greater than or equal to 98%, the product has slow-release performance, and the service life of the scanning window is prolonged by 2-3 times.

Description

Technical Field

[0001] This invention belongs to the field of atmospheric pollution control and resource utilization technology, specifically relating to a method and apparatus for oxidizing SO2 and NO in flue gas to SO3 and NO2 respectively using electron beam irradiation, absorbing them with humate solution, and simultaneously modifying humic acid in situ using irradiation energy to prepare organic slow-release fertilizer. Background Technology

[0002] Electron beam flue gas purification (EBA) is a dry technology that simultaneously desulfurizes and denitrates. Its principle is to use a high-energy electron beam to irradiate flue gas, generating a large number of active free radicals (·OH, ·O, HO2·, ·N, etc.), which oxidize SO2 and NO into high-valence oxides and react with added ammonia to generate ammonium sulfate and ammonium nitrate byproducts. This technology has the advantages of high removal efficiency and no secondary pollution, but the prominent problems are: (1) the generated ammonium sulfate / ammonium nitrate particles are small (submicron level), which easily form aerosols and are difficult to be effectively captured by traditional dust collectors, resulting in the escape of ammonium salts in the tail gas; (2) the byproducts are highly hygroscopic and deliquescent, making storage and transportation difficult; (3) when used as a single fertilizer, the nutrients are released quickly and the utilization rate is low, and long-term application can easily cause soil compaction.

[0003] Humic acid salts, as natural high-molecular-weight surfactants, have been used in wet flue gas desulfurization and denitrification due to their excellent adsorption, complexation, and foaming properties. Existing humic acid salt desulfurization and denitrification technologies mainly rely on their basic groups to neutralize acidic gases and utilize their surface activity to increase gas-liquid contact. However, the absorption efficiency of humic acid salts alone is limited, and they cannot overcome the bottleneck of slow NO oxidation rates.

[0004] Currently, there are no reports on coupling electron beam irradiation oxidation with humate absorption, and utilizing residual electron beam energy to modify humic acid in situ to prepare slow-release organic fertilizer. In particular, there is a lack of integrated reactor structural designs that can simultaneously achieve efficient flue gas purification and long-term protection of the scanning window. Summary of the Invention

[0005] This invention aims to solve the technical problems of ammonium salt byproducts being difficult to capture, prone to deliquescence, and having low fertilizer utilization in existing electron beam desulfurization and denitrification methods, as well as the susceptibility of the titanium film of the electron beam scanning window to corrosion and droplet impact damage. It provides a method and apparatus for electron beam irradiation coupled with humic acid desulfurization and denitrification, and the co-production of slow-release fertilizer. This method, while achieving efficient desulfurization and denitrification, utilizes irradiation energy to modify humic acid, generating an organic-inorganic compound fertilizer with slow-release properties. Furthermore, a dual protection system of "air curtain and interception net" significantly extends the service life of the scanning window.

[0006] To achieve the above objectives, the present invention provides a method and apparatus for electron beam irradiation coupled with humic acid desulfurization and denitrification and co-production of slow-release fertilizer, such as... Figure 1As shown, it includes the following steps: S1 Electron Beam Irradiation Oxidation: Flue gas containing SO2 and NO to be treated is introduced into the irradiation reaction zone. In the presence of ammonia, electron beam irradiation is performed at an irradiation dose of 0.5~15 kGy. The active free radicals such as ·OH, ·O, HO2·, and ·N generated by irradiation are used to oxidize SO2 in the flue gas to SO3 and NO to NO2, and to generate some ammonium sulfate and ammonium nitrate aerosols. The main reaction process is as follows.

[0007] Free radical generation: O2, H2O + e - → ·OH, ·O, HO2· (2) SO2 is oxidized to produce H2SO4: SO2 + ·O → SO3 SO3 + H2O → H2SO4 (3) NO x It oxidizes and produces nitric acid: NO + ·O → NO2, NO + HO2· → NO2 + ·OH, NO2 + ·OH → HNO3 (4) Acids react with ammonia to produce ammonium sulfate and ammonium nitrate: H₂SO₄ + 2NH₃ → (NH₄)₂SO₄ HNO3 + NH3 → NH4NO3 S2 Humic Acid Absorption and Irradiation Modification: The flue gas treated in step S1 is immediately passed into the absorption reactor, while a humic acid solution is introduced simultaneously via spraying or bubbling. This allows SO3, NO2, and incompletely oxidized SO2 and NO in the flue gas to undergo neutralization and complexation reactions with the humic acid. During this process, the active free radicals generated by electron beam irradiation act on the humic acid in the absorption liquid, causing its macromolecular structure to break down and increasing the fulvic acid content by 5-17%. Simultaneously, some carboxyl groups, phenolic hydroxyl groups, and other oxygen-containing functional groups are generated. The reaction formulas for the sulfonation and nitration of the phenyl groups in the humic acid with sulfuric acid and nitric acid are as follows: (1) The sulfonation reaction of humates produces sulfonated humates:

[0008] The nitration of humates produces nitrohumates:

[0009] The sulfonation reaction of nitrohumates produces sulfonated nitrohumates:

[0010] The main products of the above reaction are nitrohumate, sulfonated humate, and sulfonated nitrohumate. These products are easily absorbed by plants and are all high-quality organic fertilizers.

[0011] S3 Foam Capture and Product Separation: Sodium humate itself is a surfactant, and its molecular structure can significantly reduce the surface tension of the solution. It easily generates stable foam during gas-liquid mixing processes such as spraying. These tiny alkaline foams create a huge gas-liquid contact surface. When flue gas passes through, the dust and ammonium salt aerosols and other tiny particles are captured by adsorption, adhesion and coagulation. At the same time, the residual acidic gases in the flue gas can continue to react with the alkaline medium in the foam. The rich foam layer formed by the humate solution during the gas-liquid contact process is used to capture the submicron-sized ammonium sulfate / ammonium nitrate aerosols generated in S1. After the foam collapses, the aerosols mix with the absorbent to form an absorbent containing ammonium humate salt complexes. S4 product post-processing: The absorbent is concentrated and dried to obtain inorganic ammonium salt particles coated with humic acid, which is the organic-inorganic compound slow-release fertilizer.

[0012] Further, in step S1, the energy of the electron beam irradiation is 0.5~3.0 MeV, and the dose is 0.5-15 kGy. The amount of ammonia added is controlled according to the (NH3) / (SO2+NO) molar ratio of 1.5~2.2:1.

[0013] Furthermore, the humate solution has a mass concentration of 0.5% to 5%, a pH value of 8 to 11, and a liquid-to-gas ratio of 1 to 10 L / m³. 3 .

[0014] Furthermore, the absorption reactor is equipped with a gas-liquid distributor, a foam collection tank, and an irradiation window, so that the electron beam can penetrate the flue gas layer and partially irradiate the surface of the absorption liquid or the droplets.

[0015] Furthermore, the method also includes an absorbent recycling step: after solid-liquid separation, a portion of the absorbent is replenished with humic acid and water and returned to the absorption reactor for recycling.

[0016] The present invention also provides an apparatus for implementing the above method, comprising a vertical cylindrical tower body, wherein the following are arranged sequentially from bottom to top inside the tower body: (1) Flue gas inlet area: It is located at the bottom of the tower body, and the flue gas inlet is connected along the tangential direction of the tower body. An ammonia injection ring pipe is installed in this area. (2) Electron beam irradiation area: Located above the flue gas inlet area, at least two electron accelerators are symmetrically arranged on the outer side of the tower wall in this area. The scanning window of the electron accelerator extends into the tower body and emits electron beams in a horizontal or downward direction. A gas curtain protection device and a droplet interception net are installed on the outside of the scanning window. The gas curtain protection device is used to continuously blow protective gas onto the titanium film surface of the scanning window to form a positive pressure gas curtain. The droplet interception net is set on the side of the scanning window facing the inside of the tower body and is arranged parallel to the scanning window at intervals. It is used to physically intercept large-diameter droplets sputtered. The gas curtain protection device and the droplet interception net together constitute a dual protection system of "gas isolation + physical interception" for the scanning window. (3) Transition zone: Located above the irradiation zone, it is equipped with multiple perforated guide plates to guide the airflow to be evenly distributed and to prevent the spray droplets from entering the irradiation zone in the opposite direction. (4) Spray absorption zone: It is set above the transition zone. There are 2 to 4 spray layers inside from top to bottom. Each spray layer is equipped with multiple solid cone nozzles for spraying humic acid solution. (5) Demisting zone: Located above the spray absorption zone, with baffle plate demister and wire mesh demister installed in sequence inside; (6) Circulating liquid pool: Located at the bottom of the tower body, the pool is divided into a settling zone and a circulation zone by a partition.

[0017] Furthermore, the droplet interception mesh is a 316L stainless steel planar woven mesh with a wire diameter of 0.7~1.0 mm, square holes with a side length of 4~6 mm, an opening rate of not less than 40%, and a distance of 50~200 mm between it and the titanium film of the scanning window.

[0018] Furthermore, the protective gas of the gas curtain protection device is nitrogen or purified dry air with a dew point ≤ -40℃ and a gas pressure 0.5~2 kPa higher than the pressure inside the tower.

[0019] Furthermore, the number of perforated guide plates is 2 to 3 layers, the opening ratio is 30 to 50%, the hole diameter is 30 to 50 mm, and the plate thickness is 6 mm.

[0020] Furthermore, the device also includes a post-processing unit comprising a circulating pump, a foam collector, a solid-liquid separator, and a drying and granulation unit.

[0021] The inlet of the circulating pump is connected to the circulation zone of the circulating liquid tank, and the outlet of the circulating pump is connected to the inlet of the spray layer through a circulation pipeline, which is used to circulate the absorbent back into the tower for spray absorption. The inlet of the foam collector is connected to the top of the settling zone of the circulating liquid tank and is used to collect the foam layer accumulated above the liquid surface in the settling zone. The outlet is connected to the inlet of the solid-liquid separator and is used to send the defoamed absorbent into the solid-liquid separator. The bottom of the settling zone of the circulating liquid tank is provided with a drain outlet, which is connected to the inlet of the solid-liquid separator for discharging the saturated absorbent for post-treatment. The liquid phase outlet of the solid-liquid separator is connected to the circulation zone of the circulating liquid tank through a return pipeline, which is used to send the separated supernatant back to the system for recycling. The solid phase outlet of the solid-liquid separator is connected to the inlet of the drying and granulation unit, which is used to dry and granulate the dehydrated filter cake to obtain organic-inorganic composite slow-release fertilizer.

[0022] Compared with the prior art, the present invention has the following outstanding substantive features and significant progress: 1. Solving the problem of aerosol escape: Utilizing the large amount of stable foam generated by humate solution during the absorption process to form a "foam mesh", it can efficiently intercept and capture submicron-sized ammonium salt aerosols generated by electron beam method, significantly reducing particulate matter emissions in exhaust gas, with an ammonium salt capture rate of over 95%.

[0023] 2. Achieve dual utilization of irradiation energy: While the electron beam oxidizes the flue gas, the active free radicals generated by electron irradiation are used to modify the humic acid salts in the absorbent, increasing the content of small molecule active fulvic acid to 5%~17% (an increase of up to 30~60%), improving the bioactivity and chelating ability of humic acid, without the need for additional energy consumption.

[0024] 3. Obtaining high-performance slow-release fertilizer: In the generated organic-inorganic complex, humic acid combines with ammonium ions through hydrogen bonding and ion exchange to form a slow-release structure. The nutrient release period in the soil is extended to 2-3 times that of conventional ammonium salt fertilizers, and it can also improve soil aggregate structure.

[0025] 4. Synergistic Effect of Process: Electron beam irradiation requires the injection of ammonia gas to generate ammonium salts, and humic acid salts have the highest absorption efficiency for SO3 and NO2 under alkaline conditions (pH 8-11). In this invention, the addition of ammonia gas provides a suitable alkaline environment for the absorbent, eliminating the need for additional alkali to adjust the pH.

[0026] 5. Dual protection for scanning window: For the first time, a dual protection system of "air curtain and interception net" is proposed. The air curtain is responsible for isolating corrosive gases and tiny droplets and cooling the titanium film, while the interception net is specifically designed to intercept occasional large-diameter droplets that break through the air curtain. The two complement each other and are redundant and reliable, which can extend the maintenance cycle of scanning window by 2-3 times. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention. Detailed Implementation

[0028] like Figure 1As shown, an electron beam irradiation coupled humate desulfurization, denitrification, and co-production of slow-release fertilizer includes a vertical cylindrical tower, inside which are arranged sequentially from bottom to top: (1) Flue gas inlet area: It is located at the bottom of the tower body, and the flue gas inlet is connected along the tangential direction of the tower body. An ammonia injection ring pipe is installed in this area. (2) Electron beam irradiation area: Located above the flue gas inlet area, at least two electron accelerators are symmetrically arranged on the outer side of the tower wall in this area. The scanning window of the electron accelerator extends into the tower body and emits electron beams in a horizontal or downward direction. A gas curtain protection device and a droplet interception net are installed on the outside of the scanning window. The gas curtain protection device is used to continuously blow protective gas onto the titanium film surface of the scanning window to form a positive pressure gas curtain. The droplet interception net is set on the side of the scanning window facing the inside of the tower body and is arranged parallel to the scanning window at intervals. It is used to physically intercept large-diameter droplets sputtered. The gas curtain protection device and the droplet interception net together constitute a dual protection system of "gas isolation + physical interception" for the scanning window. (3) Transition zone: Located above the irradiation zone, it is equipped with multiple perforated guide plates to guide the airflow to be evenly distributed and to prevent the spray droplets from entering the irradiation zone in the opposite direction. (4) Spray absorption zone: It is set above the transition zone. There are 2 to 4 spray layers inside from top to bottom. Each spray layer is equipped with multiple solid cone nozzles for spraying humic acid solution. (5) Demisting zone: Located above the spray absorption zone, with baffle plate demister and wire mesh demister installed in sequence inside; (6) Circulating liquid pool: Located at the bottom of the tower body, the pool is divided into a settling zone and a circulation zone by a partition.

[0029] Furthermore, the droplet interception mesh is a 316L stainless steel planar woven mesh with a wire diameter of 0.7~1.0 mm, square holes with a side length of 4~6 mm, an opening rate of not less than 40%, and a distance of 50~200 mm between it and the titanium film of the scanning window.

[0030] Furthermore, the protective gas of the gas curtain protection device is nitrogen or purified dry air with a dew point ≤ -40℃ and a gas pressure 0.5~2 kPa higher than the pressure inside the tower.

[0031] Furthermore, the number of perforated guide plates is 2 to 3 layers, the opening ratio is 30 to 50%, the hole diameter is 30 to 50 mm, and the plate thickness is 6 mm.

[0032] Furthermore, the device also includes a post-processing unit comprising a circulating pump, a foam collector, a solid-liquid separator, and a drying and granulation unit.

[0033] The inlet of the circulating pump is connected to the circulation zone of the circulating liquid tank, and the outlet of the circulating pump is connected to the inlet of the spray layer through a circulation pipeline, which is used to circulate the absorbent back into the tower for spray absorption. The inlet of the foam collector is connected to the top of the settling zone of the circulating liquid tank and is used to collect the foam layer accumulated above the liquid surface in the settling zone. The outlet is connected to the inlet of the solid-liquid separator and is used to send the defoamed absorbent into the solid-liquid separator. The bottom of the settling zone of the circulating liquid tank is provided with a drain outlet, which is connected to the inlet of the solid-liquid separator for discharging the saturated absorbent for post-treatment. The liquid phase outlet of the solid-liquid separator is connected to the circulation zone of the circulating liquid tank through a return pipeline, which is used to send the separated supernatant back to the system for recycling. The solid phase outlet of the solid-liquid separator is connected to the inlet of the drying and granulation unit, which is used to dry and granulate the dehydrated filter cake to obtain organic-inorganic composite slow-release fertilizer.

[0034] The following example illustrates the process of using the above-mentioned device for humic acid desulfurization, denitrification, and co-production of slow-release fertilizer: Example 1: Take flue gas from a coal-fired boiler with a flow rate of 1000 Nm³. 3 / h, SO2 concentration is 2000 mg / m 3 NO x Concentration of 400 mg / m 3 (NO accounts for 90%). The flue gas first enters the irradiation reactor with an irradiation energy of 0.5 MeV and a dose of 0.5 kGy. Ammonia is added at a molar ratio of NH3 / (SO2+NO) of 1.5:1. After irradiation, the flue gas enters the absorption tower, where a 0.5% sodium humate solution (pH=8) is sprayed inside at a liquid-to-gas ratio of 1 L / m³. 3 After absorption, the flue gas is discharged through a demister, with an SO2 emission concentration of 38 mg / m³. 3 NO x Emission concentration 8 mg / m³ 3 The desulfurization efficiency was 98.1%, and the denitrification efficiency was 98.0%. The absorbent was concentrated and spray-dried to obtain a gray-black powder product. Testing showed that the product contained 12.3% total nitrogen (N), 28.5% humic acid, and 8.2% fulvic acid, exhibiting good slow-release properties. In this embodiment, SO2 and NO in the flue gas... xConcentration was determined using a flue gas analyzer (Testo 350XL); total nitrogen content was determined using a Kjeldahl nitrogen analyzer (K1100F) according to GB / T 17767.1-2008; humic acid and fulvic acid content were determined using a UV-Vis spectrophotometer (UV-5100) according to NY / T 1971-2010; and sustained-release performance was determined using a soil column leaching apparatus according to GB / T 23348-2009. All tests were repeated three times, and the arithmetic mean was taken as the result.

[0035] Example 2: Treatment of SO2 containing 2800 mg / m³ 3 NO x 500 mg / m 3 Coke oven flue gas, flow rate 1500 Nm 3 / h. Irradiation energy 1.8 MeV, dose 7.5 kGy, ammonia gas added at an NH3 / (SO2+NO) molar ratio of 1.85:1. A 2.75% potassium humate solution (pH=9.5) is sprayed inside the tower, with a liquid-to-gas ratio of 5.5 L / m³. 3 The SO2 emission concentration in the flue gas after absorption is 42 mg / m³. 3 NO x Emission concentration 9mg / m³ 3 The desulfurization efficiency was 98.5%, and the denitrification efficiency was 98.2%. The absorbent was concentrated and dried to obtain a gray-black powder product. Testing revealed that the product contained 12.0% total nitrogen, 29.1% humic acid, and 8.8% fulvic acid, exhibiting good slow-release properties. The testing instruments and methods were the same as in Example 1.

[0036] Example 3: Treatment of SO2 containing 3500 mg / m³ 3 NO x 600 mg / m 3 Sintering flue gas, flow rate 2000 Nm 3 / h. Irradiation energy 3.0 MeV, dose 15 kGy, ammonia gas added at an NH3 / (SO2+NO) molar ratio of 2.2:1. A 5.0% sodium humate solution (pH=11) is sprayed inside the tower, with a liquid-to-gas ratio of 10 L / m³. 3 The SO2 emission concentration in the flue gas after absorption is 17 mg / m³. 3 NO x Emission concentration 4 mg / m 3The desulfurization efficiency was 99.5%, and the denitrification efficiency was 99.3%. The absorbent was concentrated and dried to obtain a gray-black powder product. Testing revealed that the product contained 11.5% total nitrogen, 30.8% humic acid, and 9.2% fulvic acid, exhibiting good slow-release properties. The testing instruments and methods were the same as in Example 1.

[0037] Comparative example: To demonstrate the synergistic effect of this invention, a control experiment was conducted: Comparative Example 1: Using only the electron beam method (irradiation dose 3 kGy, ammonia ratio 1.5), without sodium humate solution absorption, the concentration of ammonium salt aerosol in the exhaust gas reached 45 mg / m³. 3 The product is a mixture of pure ammonium sulfate and ammonium nitrate, which is hygroscopic.

[0038] Comparative Example 2: Using only sodium humate solution (concentration 2.5%, pH=10), without electron beam irradiation, the SO2 removal efficiency was only 82%, and NO... x The removal efficiency is only 31%.

[0039] Comparative Example 3: Electron beam irradiation followed by absorption with ordinary sodium hydroxide solution (pH=10) showed high removal efficiency, but the products were sodium sulfate and sodium nitrate, which have no fertilizer value; moreover, sodium salts easily crystallize and clog the equipment, lacking foam capture function, and the aerosol content in the exhaust gas remained high (32 mg / m³). 3 ).

[0040] Comparative Example 4: Electron beam irradiation coupled with humate absorption, but without a droplet interception net, after 300 hours of operation, obvious droplet impact marks appeared on the surface of the titanium film in the scanning window, and the transmittance decreased by 5%; while in the example with an interception net, the titanium film remained intact after 800 hours of operation.

[0041] The results show that by coupling the two methods, the desulfurization and denitrification efficiency of this invention is significantly higher than that of the humate method alone. It also solves the problems of aerosol escape and fertilizer devaluation in the electron beam method. At the same time, it uses irradiation energy to modify humic acid and significantly extends the scanning window life through a dual protection system, producing a non-obvious synergistic effect.

Claims

1. A method for electron beam irradiation coupled with humic acid salt desulfurization, denitrification, and co-production of slow-release fertilizer, characterized in that, Includes the following steps: (a) Flue gas containing SO2 and NO is irradiated with an electron beam in the presence of ammonia to generate active free radicals such as ·OH, ·O, HO2·, and ·N, which oxidize SO2 to SO3 and NO to NO2, and generate ammonium salt aerosols. (b) The irradiated flue gas is brought into contact with a humate solution, and SO3 and NO2 are absorbed by the humate solution. At the same time, the active free radicals generated in step (a) are used to modify the humate in the absorption liquid in situ, thereby reducing its molecular weight and increasing its active functional groups. (c) Use the foam generated by the humate solution to capture the ammonium salt aerosol generated in step (a) to form an absorbent containing the ammonium humate complex; (d) The absorbent liquid is separated and dried to obtain an organic-inorganic compound slow-release fertilizer.

2. The method according to claim 1, characterized in that, The electron beam irradiation dose is 0.5~15 kGy and the energy is 0.5~3.0 MeV.

3. The method according to claim 1, characterized in that, The amount of ammonia added is controlled according to the total molar ratio of NH3 to SO2 and NO in the flue gas of 1.5~2.2:

1.

4. The method according to claim 1, characterized in that, The humate is one or a mixture of sodium humate, potassium humate, and ammonium humate, with a mass concentration of 0.5% to 5%, a pH value of 8 to 11, and a liquid-to-gas ratio of 1 to 10 L / m³. 3 .

5. An apparatus for implementing the method according to any one of claims 1-4, characterized in that, It includes a vertical cylindrical tower body, and the following are arranged sequentially from bottom to top inside the tower body: The flue gas inlet area is equipped with a tangential flue gas inlet and an ammonia injection ring pipe at its bottom; The electron beam irradiation zone is located above the flue gas inlet zone. At least two electron accelerators are symmetrically arranged on the outer side of the tower wall. The scanning windows of the electron accelerators extend into the tower body. A gas curtain protection device and a droplet interception net are installed on the outer side of the scanning windows. The gas curtain protection device is used to continuously blow protective gas onto the titanium film surface of the scanning window to form a positive pressure gas curtain. The droplet interception net is set on the side of the scanning window facing the inside of the tower body and is arranged parallel to the scanning window at intervals to physically intercept large-diameter droplets sputtered. The gas curtain protection device and the droplet interception net together constitute a dual protection system for the scanning window. The transition zone, located above the irradiation zone, is equipped with multiple layers of perforated guide plates. The spray absorption zone is located above the transition zone and contains 2 to 4 spray layers. The demisting zone is located above the spray absorption zone and is equipped with a baffle plate type demister and a wire mesh demister. The circulating liquid tank is integrated into the bottom of the tower body and is divided into a settling zone and a circulation zone by a baffle.

6. The apparatus according to claim 5, characterized in that, The droplet interception mesh is a stainless steel planar woven mesh with a wire diameter of 0.7~1.0 mm, square holes with a side length of 4~6 mm, an open area ratio of not less than 40%, and a distance of 50~200 mm between it and the titanium film of the scanning window.

7. The apparatus according to claim 5, characterized in that, The protective gas of the gas curtain protection device is nitrogen or purified dry air with a dew point ≤ -40℃ and a gas pressure 0.5~2 kPa higher than the pressure inside the tower.

8. The apparatus according to claim 5, characterized in that, The number of perforated guide plates is 2 to 3 layers, the opening ratio is 30 to 50%, and the hole diameter is 30 to 50 mm.

9. The apparatus according to claim 5, characterized in that, It also includes a post-processing unit: a circulating pump, a foam collector, a solid-liquid separator, and a drying and granulation unit; The inlet of the circulating pump is connected to the circulation zone of the circulating liquid tank, and the outlet of the circulating pump is connected to the inlet of the spray layer through a circulation pipeline, which is used to circulate the absorbent back into the tower for spray absorption. The inlet of the foam collector is connected to the top of the settling zone of the circulating liquid tank and is used to collect the foam layer accumulated above the liquid surface in the settling zone. The outlet is connected to the inlet of the solid-liquid separator and is used to send the defoamed absorbent into the solid-liquid separator. The bottom of the settling zone of the circulating liquid tank is provided with a drain outlet, which is connected to the inlet of the solid-liquid separator for discharging the saturated absorbent for post-treatment. The liquid phase outlet of the solid-liquid separator is connected to the circulation zone of the circulating liquid tank through a return pipeline, which is used to send the separated supernatant back to the system for recycling. The solid phase outlet of the solid-liquid separator is connected to the inlet of the drying and granulation unit, which is used to dry and granulate the dehydrated filter cake to obtain organic-inorganic composite slow-release fertilizer.

10. The apparatus according to claim 5, characterized in that, The number of electron accelerators is 2 to 6, evenly distributed around the circumference of the tower, with an electron beam energy of 0.5 to 3.0 MeV and a total irradiation dose of 0.5 to 15 kGy.

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