A low-temperature catalytic treatment system and method for low-concentration gaseous pollutants

Abstract

This application discloses a low-temperature catalytic treatment system and method for low-concentration gaseous pollutants, including a booster pump connected to a waste gas source and pressurizing the waste gas, multiple independently operable waste gas storage units, an ammonia storage unit, and a dissolution tank; it also includes a heating and temperature control mechanism and a controller. This invention, by concentrating the waste gas and quantitatively supplying it for proportional mixing and reaction, can compress low-concentration waste gas and increase the reaction concentration. Simultaneously, the multiple parallel-connected waste gas storage units can compensate for the problem of discontinuous treatment caused by the waste gas supply being less than the reaction volume, enabling this invention to achieve a balance between low-concentration, continuous, and highly efficient treatment.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to low-concentration waste gas catalytic treatment technology, specifically to a low-temperature catalytic treatment technology for nitrogen oxide waste gas, and more specifically to a low-temperature catalytic treatment system and method for low-concentration gaseous pollutants. Background Technology

[0002] Nitrogen oxides (NOx) are a series of compounds composed of nitrogen and oxygen. NOx emissions are among the most difficult to treat for waste gases. If released directly into the atmosphere without treatment, they not only pose a significant threat to the health of workers and the factory environment, but also cause pollution to surrounding residents and the ecological environment due to windblown emissions. The main hazards of nitrogen oxides include:

[0003] (1) Nitrogen oxides are very harmful to the human body, directly causing respiratory damage and are carcinogenic. (2) Nitrogen oxides can damage or even kill plants. (3) Under the catalytic effect of sunlight, nitrogen oxides easily undergo complex photochemical reactions with hydrocarbons, producing photochemical smog, leading to serious air pollution. (4) Nitrogen oxides can cause ozone layer depletion. (5) After a series of transformations in the atmosphere, nitrogen oxides can form acidic rain and fog such as nitric acid, nitrates, or nitrites, thus posing a significant threat to nature.

[0004] Existing methods for treating nitrogen oxides mainly include chemical reduction and spraying reactions. The applicant retrieved the following prior art using the search formula "((nitrogen oxides) AND (treatment) OR (exhaust gas treatment)) AND ti,ab:((exhaust gas treatment) AND (method) OR (process) OR (system))":

[0005] Prior Art 1: Chinese Invention Patent, Authorization Announcement No. CN109908733B, discloses a green and efficient method for treating nitrogen oxide waste gas. This method employs a one-step reduction process to treat nitrogen oxide waste gas. The nitrogen oxide waste gas is introduced into a waste gas treatment tower, where it is sprayed with a nitrogen oxide waste gas treatment liquid. The nitrogen oxide waste gas treatment liquid comprises the following components by weight percentage: 1%-5% soluble inorganic alkali, 10%-20% reducing agent, 0.5%-1% stabilizer, 1%-3% accelerator, and the balance being water. The accelerator is made from the following raw materials by weight: 20-30 parts organic alkali, 5-10 parts arginine, 30-40 parts sucralose-ionized trimethylglycine borohydride, 5-10 parts glucose, and 10-15 parts tetraethylenepentamine. The green and efficient nitrogen oxide waste gas treatment method disclosed in this invention can achieve safe, environmentally friendly, fast and efficient treatment of nitrogen oxide waste gas, reduce treatment costs, reduce the occurrence of secondary pollution, and the treatment process is simple, which can reduce nitrogen oxides into non-toxic and harmless nitrogen gas in one step.

[0006] Prior Art 2: Chinese Invention Patent, Authorization Announcement No. CN102974200B, discloses a nitrogen oxide waste gas treatment device and method, comprising: an acid washing unit with several acid washing absorption towers connected in series; a water washing unit including a water washing absorption tower located in series with it at a subsequent station; an alkaline washing unit including an alkaline washing absorption tower located in series with it at a subsequent station; the bottom of each absorption tower is provided with a waste gas inlet and a liquid outlet, and the top is provided with a waste gas discharge outlet and a liquid inlet, and the top of the first acid washing absorption tower is provided with an air inlet; each absorption tower is provided with a suction pump, the inlet and outlet of which are connected to the liquid outlet and the liquid inlet, respectively; an induced draft fan is connected to the waste gas discharge outlet of the alkaline washing absorption tower and the outlet is connected to the inlet of a gas-liquid separator; the exhaust port of the gas-liquid separator is connected to the air inlet of a dry adsorption tower; this invention solves the problems of existing treatment devices being unable to absorb NO, only able to absorb NO2, and generating a large amount of industrial waste salt during the waste gas treatment process, causing secondary pollution.

[0007] Of the aforementioned prior art, prior art 1 involves spraying waste gas with a novel nitrogen oxide treatment liquid, while prior art 2 uses alkaline washing and specialized spraying equipment. This application provides a completely new treatment system and method that eliminates the need for spraying and alkaline washing as in prior art 1-2, thus avoiding the need for a spray tower. Furthermore, spraying treatment methods have high recycling costs for low-concentration nitrogen oxide waste gas. This application provides a full gas-phase catalytic treatment method that is suitable for treating low-concentration waste gas and does not generate new pollutants, secondary waste gas, or wastewater after treatment, demonstrating good feasibility and practicality. Summary of the Invention

[0008] To address the pollution problem of nitrogen oxide emissions and further improve the efficient and continuous treatment of low-concentration nitrogen oxides, this application provides a low-temperature catalytic treatment system and method for low-concentration gaseous pollutants. While existing spraying or alkaline scrubbing methods can achieve continuous treatment of low-concentration waste gas, uninterrupted spraying and alkaline scrubbing are inefficient and energy-intensive for low-concentration waste gas. Generally, spraying and alkaline scrubbing are more suitable for treating high-concentration, high-content waste gas. This application employs a low-temperature catalytic treatment method for treating nitrogen oxide-containing waste gas, using pure gas-phase treatment throughout. By controlling the temperature and pressure, the concentrations of nitrogen oxides and ammonia are limited to highly efficient reaction conditions, enabling the concentration of low-concentration nitrogen oxides in the waste gas to be concentrated, improving reaction efficiency, and avoiding side reactions and the generation of secondary pollutants.

[0009] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0010] A low-temperature catalytic treatment system for low-concentration gaseous pollutants includes a booster pump connected to a waste gas source and pressurizing the waste gas. The outlet end of the booster pump is connected to multiple independently openable and closable waste gas storage units via an inlet branch pipe. The exhaust end of any waste gas storage unit is connected to a reaction tank for catalytic treatment of the waste gas via an exhaust branch pipe. One end of the reaction tank connected to the exhaust branch pipe is also connected to an ammonia storage unit for supplying ammonia. The other end of the reaction tank is provided with an exhaust manifold, and an exhaust manifold valve is provided on the exhaust manifold. The end of the exhaust manifold is connected to a diversion device for dispersing the discharged gas. The diversion device is installed in a dissolving tank and is always located below the water surface.

[0011] It also includes a heating and temperature control mechanism, which includes an oil tank for storing oil. The oil tank is connected in sequence via a heat-conducting oil pipe to multiple catalytic heat dissipation mesh boxes installed at intervals inside the reaction tank and a circulation pump installed outside the reaction tank for driving the oil circulation. It also includes a controller for controlling the oil temperature inside the oil tank. The controller is also electrically connected to the waste gas storage unit, the ammonia storage unit, the exhaust valve, the booster pump, and the reaction pressure gauge and temperature sensor installed on the reaction tank for collecting the internal pressure and temperature of the reaction tank.

[0012] To facilitate control of the waste gas supply and achieve precise supply and efficient response, the waste gas storage unit preferably includes a waste gas tank for storing waste gas, a first waste gas valve located at the inlet end of the waste gas tank, a second waste gas valve and a flow meter located at the outlet end of the waste gas tank, and a waste gas pressure gauge located on the waste gas tank for reading the internal pressure of the waste gas tank. The first waste gas valve, the waste gas pressure gauge, the second waste gas valve, and the first flow meter are all electrically connected to the controller.

[0013] More preferably, the ammonia storage unit includes an ammonia tank, a first ammonia valve disposed at the inlet end of the ammonia tank, an ammonia pressure gauge disposed on the ammonia tank for collecting the internal pressure of the ammonia tank, and a second ammonia valve and a second flow meter disposed between the ammonia tank and the reaction vessel. The first ammonia valve, the ammonia pressure gauge, the second ammonia valve and the second flow meter are all electrically connected to the controller.

[0014] To ensure the reaction temperature of the mixer remains within a preset range and facilitates dynamic adjustment, the catalytic cooling mesh box preferably includes a box body fixedly nested within the inner wall of the reaction tank, fins evenly arranged within the box body to divide the internal space into multiple slits, and heat-conducting oil pipes penetrating the fins and fixedly connected to any of the fins. The catalytic cooling mesh box serves two main functions: firstly, it rapidly dissipates heat from the heat-conducting oil pipes through the fins into the entire reaction tank, maintaining a stable, preset reaction temperature and providing favorable temperature conditions for the mixer reaction; secondly, it expands the effective catalytic area of ​​the mixer, improving catalytic efficiency. Simultaneously, the catalytic cooling mesh boxes are installed at intervals along the axis of the reaction tank, effectively dividing the tank into multiple chambers and ensuring unidirectional flow of the mixer. From entry to exit, the mixer needs to contact the fins of each catalytic cooling mesh box, thus achieving a complete catalytic reaction and reducing or even eliminating nitrogen oxide residues.

[0015] To more effectively collect unreacted gas and prevent air pollution from emissions, the diversion device preferably includes multiple thin tubes connected to the end of the exhaust manifold. Each thin tube has a microporous diversion ball installed at its free end to disperse the gas flow. The diversion ball's function is to split the gas into multiple streams composed of tiny bubbles, allowing them to react with the absorbent liquid and achieve complete absorption. Taking ammonia as an example, diverting the gas allows for more complete contact between the ammonia and water, resulting in full absorption and preventing excessive ammonia emissions into the atmosphere.

[0016] To improve the mixing degree of the gas mixture before the reaction, preferably, the end of the exhaust branch pipe extends inward through the reaction tank and then bends 180° in the opposite direction to form a first bend pipe; the end of the outlet pipe of the ammonia tank extends inward through the reaction tank and then bends 180° in the opposite direction to form a second bend pipe. The free ends of the first and second bend pipes are close to the inner wall of the reaction tank. Multiple microporous plates for improving gas turbulence are also installed inside the reaction tank between the first bend pipe and an adjacent catalytic cooling mesh box. With the above-described arrangement of the first and second bend pipes, the exhaust gas and ammonia enter the reaction tank in opposite directions to the reaction and emission, thereby creating localized turbulence and improving the uniformity of the mixture.

[0017] This invention also provides a low-temperature catalytic treatment method for low-concentration gaseous pollutants, based on the above-mentioned treatment system, specifically including the following steps:

[0018] Step P100: Close the main exhaust valve, raise the reaction tank used to treat the waste gas to the preset reaction temperature t and keep it at the temperature, wherein the reaction temperature t = 200℃-210℃;

[0019] In step P200, the booster pump pressurizes the waste gas storage units one by one in sequence. The pressurization steps for any waste gas storage unit are as follows: open the first waste gas valve, and under the action of the booster pump, the waste gas enters the waste gas tank being pressurized through the first waste gas valve until the pressure value reaches the preset pressurization value. Then, the pressure is fed back to the controller through the waste gas pressure gauge, and the first waste gas valve is closed. Then, the next waste gas storage unit is pressurized. When the waste gas flow rate of the booster pump is greater than or equal to the reaction flow rate of the reaction tank or the number of waste gas tanks pressurized meets the continuous reaction conditions of the reaction tank, proceed to step P300. Otherwise, continue to pressurize and store waste gas in other idle waste gas storage units.

[0020] Step P300: Open the second exhaust gas valve in any of the pressurized exhaust gas storage units to allow high-pressure exhaust gas to enter the reaction tank through the exhaust branch pipe until the flow rate counted by the first flow meter reaches the preset exhaust gas flow rate for a single reaction. Then, close the second exhaust gas valve through the controller. Simultaneously with opening the second exhaust gas valve, open the second ammonia valve to allow ammonia gas to enter the reaction tank until the flow rate counted by the second flow meter reaches the preset ammonia flow rate for this reaction. Then, close the second ammonia valve through the controller.

[0021] In step P400, after the waste gas and ammonia in the reaction tank react at a preset temperature for a preset time T, the exhaust main valve is opened by the controller. The reacted mixture enters the dissolution tank through the exhaust main pipe, the thin pipe and the diverter ball in sequence. Finally, it is absorbed by the copper drum dissolution tank and escapes from the surface, completing the catalytic treatment.

[0022] Preferably, the step between steps P300 and P400 further includes a step of verifying the reaction pressure inside the reaction vessel. Specifically, this includes: reading the internal pressure value Pm of the reaction vessel using a reaction pressure gauge; when Pm∈P0, proceeding to step P400; when Pm∉P0, performing pressure replenishment. The pressure replenishment process is as follows: opening the second exhaust gas valve in the next exhaust gas storage unit that has completed pressure replenishment according to the pressure increase sequence in step P200, allowing high-pressure exhaust gas to enter the reaction vessel through the exhaust branch pipe, until Pm∈P0, closing the second exhaust gas valve, and then executing step P400.

[0023] To achieve gradient treatment of different nitrogen oxides, this application further optimizes the aforementioned treatment system by providing a second reaction vessel positioned between the reaction vessel and the exhaust manifold. The purpose of the second reaction vessel is to set different reaction conditions, especially temperature conditions, for different nitrogen oxides, avoiding a series of positive and side reactions that occur under the same temperature conditions, thus preventing the reaction products from containing both the intended products and the formation of new pollutants. The two-stage reaction vessel system allows for the selection of reactants by controlling the reaction temperature, thereby achieving precise removal of nitrogen oxides.

[0024] This application also provides a low-temperature catalytic treatment method for low-concentration gaseous pollutants, implemented based on the above-mentioned optimized treatment system, specifically including the following steps:

[0025] Step P100: Close the main exhaust valve, raise the reaction tank used to treat the waste gas to the preset reaction temperature t0 and keep it warm, and raise the second reaction tank to the preset reaction temperature t1, where the reaction temperature t0 = 200℃-210℃ and t1 = 300℃.

[0026] In step P200, the booster pump pressurizes the waste gas storage units one by one in sequence. The pressurization steps for any waste gas storage unit are as follows: open the first waste gas valve, and under the action of the booster pump, the waste gas enters the waste gas tank being pressurized through the first waste gas valve until the pressure value reaches the preset pressurization value. Then, the pressure is fed back to the controller through the waste gas pressure gauge, and the first waste gas valve is closed. Then, the next waste gas storage unit is pressurized. When the waste gas flow rate of the booster pump is greater than or equal to the reaction flow rate of the reaction tank or the number of waste gas tanks pressurized meets the continuous reaction conditions of the reaction tank, proceed to step P300. Otherwise, continue to pressurize and store waste gas in other idle waste gas storage units.

[0027] Step P300: Open the second exhaust gas valve in any of the pressurized exhaust gas storage units to allow high-pressure exhaust gas to enter the reaction tank through the exhaust branch pipe until the flow rate counted by the first flow meter reaches the preset exhaust gas flow rate for a single reaction. Then, close the second exhaust gas valve through the controller. Simultaneously with opening the second exhaust gas valve, open the second ammonia valve to allow ammonia gas to enter the reaction tank until the flow rate counted by the second flow meter reaches the preset ammonia flow rate for this reaction. Then, close the second ammonia valve through the controller.

[0028] In step P400, after the waste gas and ammonia in the reaction tank react at a preset temperature for a preset time T, the exhaust main valve is opened by the controller. The reacted mixture enters the dissolution tank through the exhaust main pipe, the thin pipe and the diverter ball in sequence. Finally, it is absorbed by the copper drum dissolution tank and escapes from the surface, completing the catalytic treatment.

[0029] Beneficial effects:

[0030] 1. This invention concentrates the waste gas and supplies it quantitatively, then mixes and reacts it in proportion. This allows for the compression of low-concentration waste gas, increasing the reaction concentration. At the same time, multiple parallel waste gas storage units can compensate for the problem of discontinuous treatment caused by the waste gas supply being less than the reaction volume. This invention achieves a balance between low-concentration, continuous, and efficient treatment.

[0031] 2. The system provided by this invention has a flat design, eliminating the need to build structures similar to washing or spraying towers, thus occupying a small area. Furthermore, most of the storage tanks can be buried underground, greatly saving equipment space.

[0032] 3. The system provided by this invention is a fully dynamic closed-loop control system. The entire system collects information through front-end temperature and pressure sensors and controls gas flow through back-end valve components. The control method is simple, the system is easy to build and maintain, and multiple waste gas storage units are used as backups for each other, resulting in very high system compatibility and stability.

[0033] 4. The treatment method provided by this invention can perform gradient treatment and gradient reaction according to the type and content of nitrogen oxides in different waste gases, which effectively improves the efficiency and degree of the positive reaction, avoids the generation of side reactions, and effectively avoids the generation of new waste gases. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0036] Figure 2 yes Figure 1 Enlarged view of the structure of area A in the middle;

[0037] Figure 3 This is a schematic diagram of the heating and temperature control mechanism.

[0038] Figure 4 This is a process flow diagram of the present invention.

[0039] In the diagram: 1-Boost pump; 2-Inlet branch pipe; 3-Waste gas storage unit; 31-First waste gas valve; 32-Waste gas pressure gauge; 33-Waste gas tank; 34-Second waste gas valve; 4-Exhaust branch pipe; 41-First bend pipe; 5-Reaction tank; 51-Microporous plate; 6-First ammonia valve; 7-Ammonia tank; 8-Ammonia pressure gauge; 9-Second ammonia valve; 10-Reaction pressure gauge; 11-Temperature sensor; 12-Heating and temperature control mechanism; 121-Oil tank; 122-Circulation pump; 123-Catalytic cooling mesh box; 1231-Box body; 1232-Oil pipe; 1233-Fin; 13-Main exhaust valve; 14-Main exhaust pipe; 15-Diverter ball; 16-Dissolution tank; 17-Second bend pipe. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0042] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0043] In the description of this application, it should be noted that the use of terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These terms are used solely for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the use of terms such as "first" and "second" in the description of this application is only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0044] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this application does not imply that the component is required to be absolutely horizontal or suspended, but rather that it may be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0045] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0046] Example 1:

[0047] Refer to the instruction manual. Figure 1 The low-temperature catalytic treatment system for low-concentration gaseous pollutants shown includes a booster pump 1 connected to a waste gas source and pressurizing the waste gas. The outlet end of the booster pump 1 is connected to multiple independently openable and closable waste gas storage units 3 through an inlet branch pipe 2. The exhaust end of any waste gas storage unit 3 is connected to a reaction tank 5 for catalytic treatment of waste gas through an exhaust branch pipe 4. One end of the reaction tank 5 connected to the exhaust branch pipe 4 is also connected to an ammonia storage unit for providing ammonia. The other end of the reaction tank 5 is provided with an exhaust manifold 14. An exhaust manifold valve 13 is provided on the exhaust manifold 14. The end of the exhaust manifold 14 is connected to a diversion device for dispersing the discharged gas. The diversion device is installed in a dissolving tank 16 and is always located below the water surface.

[0048] It also includes a heating and temperature control mechanism 12, which includes an oil tank 121 for storing oil. The oil tank 121 is connected in sequence to a plurality of catalytic heat dissipation mesh boxes 123 installed at intervals inside the reaction tank 5 and a circulation pump 122 installed outside the reaction tank 5 for driving the oil circulation flow, and a controller for controlling the oil temperature inside the oil tank 121. The controller is also electrically connected to the waste gas storage unit 3, the ammonia storage unit, the exhaust valve 13, the booster pump 1, and the reaction pressure gauge 10 and temperature sensor 11 installed on the reaction tank 5 for collecting the internal pressure and temperature of the reaction tank 5, respectively.

[0049] Working principle:

[0050] The inlet of the booster pump 1 pressurizes the waste gas from the waste gas source and then fills it one by one into the waste gas storage unit 3. When the amount stored in the waste gas storage unit 3 is sufficient to meet the waste gas supply for the continuous reaction of the reaction tank 5, it starts to supply pressurized waste gas to the reaction tank 5. At the same time, ammonia is supplied to the reaction tank 5 through the ammonia storage unit. The heating and temperature control mechanism 12 heats the reaction tank 5 and maintains it at a preset constant temperature to ensure the efficient reaction of the waste gas.

[0051] There are two main factors affecting the reaction efficiency of nitrogen oxide waste gas and ammonia: temperature and pressure. Catalysts are a mature and readily available technology; commonly used catalysts include metal catalysts such as aluminum, nickel, and cobalt. The role of the catalyst is to lower the activation energy of the reaction and increase the reaction rate. Furthermore, the catalyst can improve the selectivity of the reaction and avoid unnecessary side reactions. In this embodiment, the catalyst is placed on the catalytic heat dissipation mesh box 123. When the mixed gas flow passes through the reaction tank 5, it comes into contact with the catalytic heat dissipation mesh box 123 to achieve the purpose of catalytic reaction.

[0052] Compared with existing spraying or flow-through reactions, the improvements and advantages of this embodiment are as follows:

[0053] After being pressurized by booster pump 1, the waste gas is stored in waste gas storage unit 3 at a preset pressure value, for example, 4 MPa. Similarly, the ammonia storage unit is connected to an ammonia source to provide sufficient ammonia for the reaction. During the reaction, the temperature and pressure inside the reaction tank 5 are adjusted by the controller to ensure good reaction conditions. At the same time, by controlling the gas supply of waste gas storage unit 3 and ammonia storage unit, a mixed gas of preset concentration and ratio is obtained to achieve the best energy efficiency reaction effect. Of course, it is worth noting that in the conventional treatment process, the set value should be appropriately increased based on the theoretical optimal ratio to avoid insufficient ammonia reaction and nitrogen oxide residue due to fluctuations in the concentration of nitrogen oxides in the waste gas source. Excess ammonia can be treated in the subsequent dissolution tank 16 without causing environmental pollution. This embodiment only provides a treatment system. The preset value setting depends on the actual waste gas source being treated and is irrelevant to this system, so it will not be elaborated here.

[0054] After a single treatment cycle, the main exhaust valve 13 is opened to release the treated waste gas. The treated waste gas mainly consists of nitrogen, water vapor, and excess ammonia, which is dissolved in the dissolution tank 16 and then discharged into the atmosphere. The waste gas from subsequent waste gas storage units 3 is then circulated for further treatment. It is worth noting that since there are multiple waste gas storage units 3, the order of pressurization and gas supply can be manually set and is not limited in this application. For example, assuming there are 10 waste gas storage units 3, the waste gas can be pressurized and stored in order of numbers 1-10, and simultaneously discharged in the same order. During discharge, the diversion device effectively increases the contact between ammonia and water, achieving full dissolution and preventing excess ammonia from escaping. Of course, the system described in this embodiment is also applicable to the treatment of other waste gases; it simply requires replacing the water in the dissolution tank 16 with other chemical reagents that can react with the product gas, which is obvious to those skilled in the art.

[0055] Example 2:

[0056] Based on the structure and principle of Example 1, and further in conjunction with the appendix to the instruction manual... Figures 1-3 As shown, in order to facilitate the control of the supply of exhaust gas and achieve the effect of precise supply and efficient response, in this embodiment, the exhaust gas storage unit 3 includes an exhaust gas tank 33 for storing exhaust gas, a first exhaust gas valve 31 set at the inlet end of the exhaust gas tank 33, a second exhaust gas valve 34 and a flow meter set at the outlet end of the exhaust gas tank 33, and an exhaust gas pressure gauge 32 set on the exhaust gas tank 33 for reading the internal pressure of the exhaust gas tank 33. The first exhaust gas valve 31, the exhaust gas pressure gauge 32, the second exhaust gas valve 34 and the first flow meter are all electrically connected to the controller. When pressurizing the exhaust gas, the first exhaust gas valve 31 is opened. Under the action of the booster pump 1, the exhaust gas passes through the first exhaust gas valve 31 and enters the currently pressurized exhaust gas tank 33. When the pressure value reaches the preset boosting value, the controller is fed back through the exhaust gas pressure gauge 32 and the first exhaust gas valve 31 is closed. Then the next exhaust gas storage unit 3 is pressurized. The advantage of this is that the exhaust gas storage unit 3 can concentrate the small flow and low concentration of exhaust gas and supply it according to the actual reaction rate, thereby dealing with application scenarios with low concentration and low emission.

[0057] In this embodiment, the ammonia storage unit includes an ammonia tank 7, a first ammonia valve 6 disposed at the inlet end of the ammonia tank 7, an ammonia pressure gauge 8 disposed on the ammonia tank 7 for collecting the internal pressure of the ammonia tank 7, and a second ammonia valve 9 and a second flow meter disposed between the ammonia tank 7 and the reaction vessel 5. The first ammonia valve 6, the ammonia pressure gauge 8, the second ammonia valve 9 and the second flow meter are all electrically connected to the controller.

[0058] To ensure the mixer's reaction temperature remains within the preset range and to facilitate dynamic adjustment, please refer to the instruction manual. Figure 3 As shown, the catalytic heat dissipation mesh box 123 includes a box body 1231 fixedly nested in the inner wall of the reaction tank 5, fins 1233 evenly arranged in the box body 1231 to divide the internal space of the box body 1231 into multiple slits, and a heat-conducting oil pipe that passes through the fins 1233 and is fixedly connected to any fin 1233. The catalytic heat dissipation mesh box 123 has two main functions: firstly, it rapidly dissipates the heat from the heat transfer oil pipes to the entire reaction tank 5 through the fins 1233, ensuring that the temperature in the reaction tank 5 remains stable at the preset reaction temperature, providing favorable temperature conditions for the mixer reaction; secondly, it expands the effective catalytic area of ​​the mixer and improves catalytic efficiency. Simultaneously, the catalytic heat dissipation mesh box 123 is installed at intervals along the axis of the reaction tank 5, effectively dividing the reaction tank 5 into multiple chambers. This ensures that the mixer can only flow in one direction. From the moment the mixer enters the reaction tank 5 until it exits, it needs to contact the fins 1233 of each catalytic heat dissipation mesh box 123, thereby achieving a full catalytic reaction and reducing or even eliminating nitrogen oxide residues.

[0059] To more effectively collect unreacted gases and avoid air pollution from emissions, see [link to relevant documentation]. Figure 1 As shown, the diversion device includes multiple thin tubes connected to the end of the exhaust manifold 14. Each thin tube has a microporous diversion ball 15 installed at its free end to disperse the gas flow. The diversion ball 15 functions to divert the gas into multiple streams of tiny bubbles, allowing them to react with the absorbent liquid and achieve complete absorption. Taking ammonia as an example, diverting the gas allows for more complete contact between the ammonia and water, resulting in full absorption and preventing excessive ammonia emissions into the atmosphere.

[0060] To improve the mixing degree of the gas mixture before the reaction, see Figure 2 As shown, the end of the exhaust branch pipe 4 extends inward through the reaction tank 5 and then bends 180° in the opposite direction to form a first bend pipe 41; the end of the outlet pipe of the ammonia tank 7 extends inward through the reaction tank 5 and then bends 180° in the opposite direction to form a second bend pipe 17. The free ends of the first bend pipe 41 and the second bend pipe 17 are close to the inner wall of the end of the reaction tank 5. Multiple microporous plates 51 for improving gas turbulence are also provided inside the reaction tank 5 between the first bend pipe 41 and an adjacent catalytic cooling mesh box 123. With the above-described arrangement of the first bend pipe 41 and the second bend pipe 17, the exhaust gas and ammonia enter the reaction tank 5 in opposite directions of reaction and emission, thereby creating localized turbulence and improving the uniformity of mixing.

[0061] Example 3:

[0062] See Figure 4 As shown, this embodiment provides a low-temperature catalytic treatment method for low-concentration gaseous pollutants, implemented based on the treatment system described in Embodiment 2 above. This embodiment focuses on nitric oxide as the waste gas pollutant and specifically includes the following steps:

[0063] Step P100: Close the main exhaust valve 13, raise the reaction tank 5 used for treating waste gas to the preset reaction temperature t and keep it warm, wherein the reaction temperature t = 200℃-210℃;

[0064] The reaction between NO and NH3 at a temperature t = 200℃-210℃ is as follows:

[0065] 4NH3 + 6NO == 5N2 + 6H2O

[0066] In step P200, the booster pump 1 pressurizes the waste gas storage units 3 one by one in sequence. The pressurization steps for any waste gas storage unit 3 are as follows: the first waste gas valve 31 is opened, and under the action of the booster pump 1, the waste gas enters the waste gas tank 33 that is being pressurized through the first waste gas valve 31 until the pressure value reaches the preset pressurization value. Then, the pressure is fed back to the controller through the waste gas pressure gauge 32 and the first waste gas valve 31 is closed. Then, the next waste gas storage unit 3 is pressurized. When the waste gas flow rate of the booster pump 1 is greater than or equal to the reaction flow rate of the reaction tank 5 or the number of waste gas tanks pressurized meets the continuous reaction conditions of the reaction tank 5, step P300 is performed. Otherwise, the other idle waste gas storage units 3 are pressurized to store waste gas.

[0067] Step P300: Open the second exhaust gas valve 34 in any of the pressurized exhaust gas storage units 3 to allow high-pressure exhaust gas to enter the reaction tank 5 through the exhaust branch pipe 4 until the flow rate counted by the first flow meter reaches the preset exhaust gas flow rate for a single reaction. Then, close the second exhaust gas valve 34 through the controller. At the same time as opening the second exhaust gas valve 34, open the second ammonia valve 9 to allow ammonia gas to enter the reaction tank 5 until the flow rate counted by the second flow meter reaches the preset ammonia gas flow rate for this reaction. Then, close the second ammonia valve 9 through the controller.

[0068] In step P400, after the waste gas and ammonia in the reaction tank 5 react at a preset temperature for a preset time T, the exhaust valve 13 is opened by the controller. The reacted mixture enters the dissolution tank 16 through the exhaust manifold 14, the thin pipe and the diverter ball 15 in sequence. Finally, after being absorbed by the copper drum dissolution tank 16, it escapes from the surface, completing the catalytic treatment.

[0069] As a preferred processing method in this embodiment, the step between steps P300 and P400 also includes a step of verifying the reaction pressure inside the reaction tank 5. Specifically, this includes: reading the internal pressure value Pm of the reaction tank 5 through the reaction pressure gauge 10; when Pm∈P0, proceeding to step P400; when Pm∉P0, performing pressure replenishment. The pressure replenishment process is as follows: opening the second exhaust gas valve 34 in the next exhaust gas storage unit 3 that has completed pressure replenishment according to the pressure increase sequence in step P200, allowing high-pressure exhaust gas to enter the reaction tank 5 through the exhaust branch pipe 4, until Pm∈P0, closing the second exhaust gas valve 34, and then executing step P400. Where P0 = 2.5 MPa - 4 MPa.

[0070] Example 4:

[0071] To achieve gradient treatment of different nitrogen oxides, the treatment system is further optimized based on Example 3 above. This example provides a second reaction tank located between the reaction tank 5 and the exhaust manifold 14. The purpose of setting up the second reaction tank is to set different reaction conditions, especially temperature conditions, for different nitrogen oxides, avoiding a series of positive and side reactions of nitrogen oxides under the same temperature conditions, so that the reaction products contain both the expected products and the formation of new pollutants. Setting up a two-stage reaction tank allows for the screening of reactants by controlling the reaction temperature, thereby achieving the goal of precise removal of nitrogen oxides.

[0072] Another low-temperature catalytic treatment method for low-concentration gaseous pollutants provided in this embodiment is based on the above-mentioned optimized treatment system and specifically includes the following steps:

[0073] Step P100: Close the main exhaust valve 13, raise the reaction tank 5 used for treating waste gas to the preset reaction temperature t0 and keep it warm, raise the second reaction tank to the preset reaction temperature t1, where the reaction temperature t0 = 200℃-210℃, t1 = 300℃;

[0074] In reaction vessel 5, at a temperature of t0 = 200℃-210℃, the reaction between NO and NH3 is as follows:

[0075] 4NH3 + 6NO == 5N2 + 6H2O

[0076] In the second reaction vessel, at a temperature t1 = 300℃, the reaction between NO2 and NH3 is as follows:

[0077] 8NH3 + 6NO2 = 7N2 + 12H2O

[0078] Because the temperature is low in the reaction vessel, NO2 and NH3 will not react. In the second reaction vessel, N2 is in a stable state and will not participate in the reaction, thus achieving a staged reaction and treating different nitrogen oxides separately. At the same time, no new reactants are added, and only ammonia gas needs to be introduced throughout the process. By controlling the process parameters separately, the occurrence of side reactions can also be avoided, achieving a double benefit.

[0079] In step P200, the booster pump 1 pressurizes the waste gas storage units 3 one by one in sequence. The pressurization steps for any waste gas storage unit 3 are as follows: the first waste gas valve 31 is opened, and under the action of the booster pump 1, the waste gas enters the waste gas tank 33 that is being pressurized through the first waste gas valve 31 until the pressure value reaches the preset pressurization value. Then, the pressure is fed back to the controller through the waste gas pressure gauge 32 and the first waste gas valve 31 is closed. Then, the next waste gas storage unit 3 is pressurized. When the waste gas flow rate of the booster pump 1 is greater than or equal to the reaction flow rate of the reaction tank 5 or the number of waste gas tanks pressurized meets the continuous reaction conditions of the reaction tank 5, step P300 is performed. Otherwise, the other idle waste gas storage units 3 are pressurized to store waste gas.

[0080] Step P300: Open the second exhaust gas valve 34 in any of the pressurized exhaust gas storage units 3 to allow high-pressure exhaust gas to enter the reaction tank 5 through the exhaust branch pipe 4 until the flow rate counted by the first flow meter reaches the preset exhaust gas flow rate for a single reaction. Then, close the second exhaust gas valve 34 through the controller. At the same time as opening the second exhaust gas valve 34, open the second ammonia valve 9 to allow ammonia gas to enter the reaction tank 5 until the flow rate counted by the second flow meter reaches the preset ammonia gas flow rate for this reaction. Then, close the second ammonia valve 9 through the controller.

[0081] In step P400, after the waste gas and ammonia in the reaction tank 5 react at a preset temperature for a preset time T, the exhaust valve 13 is opened by the controller. The reacted mixture enters the dissolution tank 16 through the exhaust manifold 14, the thin pipe and the diverter ball 15 in sequence. Finally, after being absorbed by the copper drum dissolution tank 16, it escapes from the surface, completing the catalytic treatment.

[0082] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A low-temperature catalytic treatment system for low-concentration gaseous pollutants, characterized in that: The system includes a booster pump (1) connected to the waste gas source and pressurizing the waste gas. The outlet end of the booster pump (1) is connected to multiple independently openable and closable waste gas storage units (3) through an air inlet branch pipe (2). The exhaust end of any waste gas storage unit (3) is connected to a reaction tank (5) for catalytic treatment of waste gas through an exhaust branch pipe (4). One end of the reaction tank (5) connected to the exhaust branch pipe (4) is also connected to an ammonia storage unit for providing ammonia. The other end of the reaction tank (5) is provided with an exhaust manifold (14). An exhaust manifold valve (13) is provided on the exhaust manifold (14). The end of the exhaust manifold (14) is connected to a diversion device for dispersing the discharged gas. The diversion device is installed in the dissolving tank (16) and is always located below the water surface. It also includes a heating and temperature control mechanism (12), which includes an oil tank (121) for storing oil. The oil tank (121) is connected in sequence to a plurality of catalytic heat dissipation mesh boxes (123) installed at intervals in the reaction tank (5) and a circulation pump (122) set outside the reaction tank (5) for driving the oil circulation flow, and a controller for controlling the oil temperature inside the oil tank (121). The controller is also electrically connected to the waste gas storage unit (3), the ammonia storage unit, the exhaust valve (13), the booster pump (1), and the reaction pressure gauge (10) and temperature sensor (11) set on the reaction tank (5) respectively for collecting the internal pressure and temperature of the reaction tank (5). The waste gas storage unit (3) includes a waste gas tank (33) for storing waste gas, a first waste gas valve (31) provided at the inlet end of the waste gas tank (33), a second waste gas valve (34) and a flow meter provided at the outlet end of the waste gas tank (33), and a waste gas pressure gauge (32) provided on the waste gas tank (33) for reading the internal pressure of the waste gas tank (33). The first waste gas valve (31), the waste gas pressure gauge (32), the second waste gas valve (34) and the first flow meter are all electrically connected to the controller. The ammonia storage unit includes an ammonia tank (7), a first ammonia valve (6) installed at the inlet end of the ammonia tank (7), an ammonia pressure gauge (8) installed on the ammonia tank (7) for collecting the internal pressure of the ammonia tank (7), and a second ammonia valve (9) and a second flow meter installed between the ammonia tank (7) and the reaction vessel (5). The first ammonia valve (6), the ammonia pressure gauge (8), the second ammonia valve (9) and the second flow meter are all electrically connected to the controller. The catalytic heat dissipation mesh box (123) includes a box body (1231) fixedly nested in the inner wall of the reaction tank (5), fins (1233) evenly arranged in the box body (1231) to divide the internal space of the box body (1231) into multiple slits, and a heat-conducting oil pipe that passes through the fins (1233) and is fixedly connected to any fin (1233).

2. The low-temperature catalytic treatment system for low-concentration gaseous pollutants according to claim 1, characterized in that: The diversion device includes multiple thin tubes connected to the end of the exhaust manifold (14), and each thin tube has a microporous diversion ball (15) installed at its free end for dispersing the airflow.

3. The low-temperature catalytic treatment system for low-concentration gaseous pollutants according to claim 2, characterized in that: The end of the exhaust branch pipe (4) extends through the reaction tank (5) and then bends 180° in the opposite direction to form a first bend pipe (41); the end of the outlet pipe of the ammonia tank (7) extends through the reaction tank (5) and then bends 180° in the opposite direction to form a second bend pipe (17). The free ends of the first bend pipe (41) and the second bend pipe (17) are close to the inner wall of the end of the reaction tank (5). A number of microporous plates (51) for improving gas turbulence are also provided in the reaction tank (5) between the first bend pipe (41) and an adjacent catalytic heat dissipation mesh box (123).

4. The low-temperature catalytic treatment system for low-concentration gaseous pollutants according to claim 3, characterized in that: It also includes a second reaction vessel located between the reaction vessel (5) and the exhaust manifold (14).

5. A low-temperature catalytic treatment method for low-concentration gaseous pollutants, characterized in that: The processing system based on claim 3 is implemented by specifically including the following steps: Step P100: Close the main exhaust valve (13), raise the reaction tank (5) used for treating waste gas to the preset reaction temperature t and keep it warm, wherein the reaction temperature t = 200℃-210℃; In step P200, the booster pump (1) pressurizes the waste gas storage units (3) one by one in sequence. The pressurization steps of any waste gas storage unit (3) are as follows: open the first waste gas valve (31), and under the action of the booster pump (1), the waste gas enters the waste gas tank (33) being pressurized through the first waste gas valve (31) until the pressure value reaches the preset pressurization value. Then, the pressure gauge (32) feeds back to the controller and closes the first waste gas valve (31). Then, the next waste gas storage unit (3) is pressurized. When the waste gas flow rate of the booster pump (1) is greater than or equal to the reaction flow rate of the reaction tank (5) or the number of waste gas tanks pressurized meets the continuous reaction conditions of the reaction tank (5), step P300 is performed. Otherwise, the other idle waste gas storage units (3) are pressurized to store waste gas. Step P300: Open the second exhaust valve (34) in any of the pressurized exhaust gas storage units (3) to allow the high-pressure exhaust gas to enter the reaction tank (5) through the exhaust branch pipe (4) until the flow rate counted by the first flow meter reaches the preset exhaust gas flow rate for a single reaction, and then close the second exhaust valve (34) through the controller; at the same time as opening the second exhaust valve (34), open the second ammonia valve (9) to allow ammonia to enter the reaction tank (5) until the flow rate counted by the second flow meter reaches the preset ammonia flow rate for this reaction, and then close the second ammonia valve (9) through the controller. In step P400, after the waste gas and ammonia in the reaction tank (5) react at a preset temperature for a time T, the exhaust valve (13) is opened by the controller. The reacted mixture enters the dissolution tank (16) through the exhaust manifold (14), the thin pipe and the diverter ball (15) in sequence. After being absorbed by the copper drum dissolution tank (16), it escapes from the surface, completing the catalytic treatment.

6. The low-temperature catalytic treatment method for low-concentration gaseous pollutants according to claim 5, characterized in that: Between steps P300 and P400, there is also a step to verify the reaction pressure inside the reaction tank (5), specifically including: reading the internal pressure value Pm of the reaction tank (5) through the reaction pressure gauge (10). When Pm∈P0, step P400 is performed. When Pm∉P0, pressure is replenished. The pressure replenishment process is as follows: according to the pressure increase sequence in step P200, the second exhaust gas valve (34) in the next exhaust gas storage unit (3) that has completed pressure increase is opened, and the high pressure exhaust gas is introduced into the reaction tank (5) through the exhaust branch pipe (4) until Pm∈P0 is closed, and then step P400 is executed. Wherein, P0=2.5 ​​MPa -4 MPa.

7. A low-temperature catalytic treatment method for low-concentration gaseous pollutants, characterized in that: The processing system based on claim 4 is implemented by specifically including the following steps: Step P100: Close the main exhaust valve (13), raise the reaction tank (5) used to treat the waste gas to the preset reaction temperature t0 and keep it warm, raise the second reaction tank to the preset reaction temperature t1, where the reaction temperature t0 = 200℃-210℃, t1 = 300℃; In step P200, the booster pump (1) pressurizes the waste gas storage units (3) one by one in sequence. The pressurization steps of any waste gas storage unit (3) are as follows: open the first waste gas valve (31), and under the action of the booster pump (1), the waste gas enters the waste gas tank (33) being pressurized through the first waste gas valve (31) until the pressure value reaches the preset pressurization value. Then, the pressure gauge (32) feeds back to the controller and closes the first waste gas valve (31). Then, the next waste gas storage unit (3) is pressurized. When the waste gas flow rate of the booster pump (1) is greater than or equal to the reaction flow rate of the reaction tank (5) or the number of waste gas tanks pressurized meets the continuous reaction conditions of the reaction tank (5), step P300 is performed. Otherwise, the other idle waste gas storage units (3) are pressurized to store waste gas. Step P300: Open the second exhaust valve (34) in any of the pressurized exhaust gas storage units (3) to allow the high-pressure exhaust gas to enter the reaction tank (5) through the exhaust branch pipe (4) until the flow rate counted by the first flow meter reaches the preset exhaust gas flow rate for a single reaction, and then close the second exhaust valve (34) through the controller; at the same time as opening the second exhaust valve (34), open the second ammonia valve (9) to allow ammonia to enter the reaction tank (5) until the flow rate counted by the second flow meter reaches the preset ammonia flow rate for this reaction, and then close the second ammonia valve (9) through the controller. In step P400, after the waste gas and ammonia in the reaction tank (5) react at a preset temperature for a time T, the exhaust valve (13) is opened by the controller. The mixture after the reaction enters the dissolution tank (16) through the exhaust manifold (14), the thin pipe and the diverter ball (15) in sequence. Finally, it is absorbed by the dissolution tank (16) and escapes from the surface to complete the catalytic treatment.

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