Method and device for treating air pollution in rubber asphalt production

Abstract

The invention discloses a method and device for treating air pollution in rubber asphalt production, and belongs to the technical field of environmental protection. According to the method, three-stage treatment is adopted, and the first-stage treatment is cooling and waste removal treatment: flue gas is fed into a reaction kettle, so that harmful substances in the flue gas are dissolved while the flue gas is cooled; the secondary treatment is plasma treatment, a strong electric field is used for generating plasmas, smoke pollutant molecules are attacked, chemical bonds of the smoke pollutant molecules are destroyed, and finally the smoke pollutant molecules are converted into harmless small molecules; and the third-stage treatment is to reduce the total emission amount of harmful gas in production. The device solves the problem of air pollution in the rubber asphalt production process, and has the characteristics of low pollution to the surrounding environment, low energy consumption and high asphalt mixing speed.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, specifically to a technology for treating flue gas emitted during the production of rubber asphalt, and removing complex pollutants such as volatile organic compounds (VOCs), particulate matter, tar, and sulfides mixed in the flue gas. Background Technology

[0002] In the traditional rubber asphalt production process, rubber powder (hereinafter referred to as rubber powder) and base asphalt are mixed at high temperatures (usually 160-180℃). During the process of adding rubber powder to asphalt and in the subsequent mixing process, environmental protection and governance issues are prominent, with the following problems: First, flue gas pollution. The production process releases a large amount of harmful gases, including benzene series compounds (such as benzene, toluene, xylene, benzothiazole), hydrogen sulfide (H2S), nitrogen oxides (NOx), and polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic. The flue gas composition is complex and has strong adhesion. Traditional treatment methods, such as single activated carbon adsorption, have problems such as easy saturation of adsorbents, high risk of secondary pollution, and high energy consumption. Secondly, traditional rubber powder addition to asphalt is mostly done in open production processes, resulting in large emissions of flue gas. Furthermore, as a product of waste tire recycling, rubber powder often has residual sulfides and cross-linked structures on its surface, leading to poor compatibility with asphalt. During the addition process, rubber powder agglomeration is prone to occur, and uneven mixing of rubber powder and asphalt reduces the mechanical properties of rubberized asphalt, such as rutting resistance and fatigue life. To achieve a thorough mixing effect, higher temperatures and longer mixing times are often required, which not only increases energy consumption but also inevitably increases the emission of harmful gases and substances due to the extended mixing time. Thirdly, dust pollution exists during the addition of rubber powder to asphalt. Dust is mainly generated during the rubber powder feeding, conveying, and mixing stages. Dust pollution is easily generated during the rubber powder feeding process and must be strictly controlled.

[0003] Chinese patent application number "202022120660.7", entitled "A Dust Recovery Device for Asphalt Concrete Production", uses an installed suction fan to draw dust generated inside the asphalt concrete production tank into a dust collection box. This allows for the filtration, recovery, and treatment of dust emitted during asphalt concrete production, preventing direct dust discharge. While it has a certain effect on dust pollution control, it does not address the issue of how to treat pollution caused by volatile organic compounds (VOCs).

[0004] The application, with application number "202022452225.4" and titled "An Asphalt Waste Gas Treatment Device," uses a waste gas rectifier plate to rectify the waste gas, a metal honeycomb catalytic plate to adsorb harmful substances in the waste gas, and then uses high-ozone UV ultraviolet lamps to irradiate the waste gas, degrading it into low-molecular-weight compounds. It primarily treats simple asphalt waste gas and does not address the issues of harmful gases and dust pollution generated by heating rubber asphalt.

[0005] Therefore, researching a targeted method and apparatus for controlling air pollution, in response to the serious environmental pollution problem in rubber asphalt production, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] This invention aims to overcome the deficiencies of existing technologies and provides a method for controlling air pollution in the production of rubber asphalt. This method can remove harmful gases and dust from flue gas and prevent pollution to the surrounding environment. In addition, this invention also provides the apparatus used in this method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for controlling air pollution during rubber asphalt production, the method employing a three-stage treatment process, specifically including: The primary treatment is cooling and waste removal treatment: the fumes emitted during the preparation of rubber asphalt are collected and centrally treated. The fumes are collected by using a negative pressure created by an air pump at the collection hood and sent into the reaction vessel. The fumes are turned into bubbles by the air hole array set on the aeration pipe and pass through the cooling and cleaning liquid layer. While the fumes are cooled in the solution, some of the harmful substances inside are dissolved. Secondary treatment is plasma treatment: After primary treatment, the flue gas enters the plasma processor after passing through the dehumidifier. The strong electric field is used to ionize the oxygen molecules in the air to generate plasma, which is rich in high-energy electrons, ozone and free radicals. This plasma attacks the flue gas pollutant molecules, breaks their chemical bonds, and finally converts them into harmless small molecules such as CO2 and H2O. The third-level treatment involves controlling the total emissions: the mixing drum is sealed, and a frustum-shaped mixing hood is installed inside the sealed mixing drum to achieve rapid and initial uniform mixing of asphalt and rubber powder. The asphalt is then rapidly heated with hot oil, and rotating mixing blades are used to perform high-speed shearing and mixing of the asphalt and rubber powder. The entire process reduces the mixing time of rubber powder and asphalt in the production process, effectively reducing the emission of harmful fumes in terms of total emissions.

[0008] In the above-mentioned method for controlling air pollution in rubber asphalt production, the plasma processor uses a flat plate electrode, which is connected to a radio frequency power supply. The radio frequency parameters are set as follows: frequency 5-8MHz, peak voltage 0.7-12 kV, electrode spacing 2-4mm. The surface of the flat plate electrode is covered with a quartz glass layer with a thickness of 0.5-3mm. Asphalt fumes enter from one end of the plasma processor, are treated by the plasma, and then flow out from the other end.

[0009] In the above-mentioned method for controlling air pollution in rubber asphalt production, the cooling and cleaning solution is an aqueous solution of NaOH or Na2CO3 with a concentration of 0.5-2%, used to cool the flue gas and absorb acidic gases in the flue gas, such as hydrogen sulfide, sulfur dioxide, some organic acids and phenols.

[0010] A treatment device for a method of controlling air pollution in rubber asphalt production, the device comprising a flue gas treatment section and a production control section; The flue gas treatment section includes a collection hood, a reaction vessel, a dehumidifier, and a plasma processor; the reaction vessel contains a cooling cleaning liquid, and an aeration pipe is installed at the bottom of the cooling cleaning liquid; the collection hood is located above the stirring drum, and is connected to the aeration pipe through a pipe, in which an air pump is installed; the flue gas discharged from the reaction vessel flows through the dehumidifier and the plasma processor in sequence before being discharged. The production control section includes a mixing drum and a mixing section and a stirring section arranged sequentially from top to bottom inside it. The mixing section includes a mixing hood, which is a frustum-shaped shell structure. It is mounted on a central shaft and can rotate. After the rubber powder and asphalt are initially mixed on the rotating mixing hood, they fall downward into the asphalt in the mixing drum.

[0011] The treatment device used in the above-mentioned method for treating air pollution in rubber asphalt production includes a rubber powder blowing section and an asphalt spray pipe on the mixing drum; the discharge direction of the rubber powder blowing section and the asphalt spray pipe is towards the mixing hood. Beneficial effects

[0012] Compared with the prior art, the present invention has the following advantages: 1. This invention includes a reaction vessel containing a solution for cooling and flue gas cleaning, which removes acidic gases such as hydrogen sulfide, sulfur dioxide, some organic acids, and phenols such as phenol and cresol from the flue gas. The array of air holes on the aeration pipes in the reaction vessel disperses the airflow into numerous bubbles that pass through the solution layer, ensuring more thorough contact between the asphalt flue gas and the solution, resulting in a faster and more complete reaction and better removal of harmful components.

[0013] 2. The plasma processor employs a dual-electrode parallel plate structure with a millimeter-level gap between them. Gas flows through and is broken down, forming numerous filamentary micro-discharge channels. The quartz glass layer surrounding the electrodes limits the unlimited current growth, preventing thermal arcs and ensuring uniform and stable discharge. Furthermore, the smooth quartz surface makes it easy to clean. Within the discharge channels, electrons gain extremely high energy and collide violently with gas molecules, generating not only ions and electrons but also a large number of active free radicals, excited-state molecules, and ultraviolet radiation, all of which can act on the harmful components in the asphalt fume.

[0014] 3. In order to reduce the total amount of harmful gases emitted during production, the present invention is equipped with a rotatable mixing hood to achieve rapid and uniform mixing. By utilizing the efficient mixing of the mixing hood and the rapid heating of the heating unit, the time required in the production process is greatly reduced, thereby effectively reducing the total amount of harmful flue gas emissions. Attached Figure Description

[0015] The invention will now be described in further detail with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic diagram of the overall steps of the present invention; Figure 2 This is a schematic diagram of the device used in this invention; Figure 3 This is a schematic diagram of the mixing section; Figure 4 This is a schematic diagram of the transmission of the mixing cover; Figure 5 This is a schematic diagram of the heating element structure; Figure 6 This is a schematic diagram of the adhesive powder blowing section; The labels in the diagram represent: 1-1. Reactor; 1-2. Dehumidifier; 1-3. Plasma processor; 1-4. Aeration pipe; 1-5. Air pump; 1-6. Collection hood; 1-7. Radio frequency power supply; 2-1. Mixing hood; 2-2. Central shaft; 2-3. Upper support; 2-4. Lower support; 2-5. Conical protrusion; 2-6. First bearing seat; 2-7. Hydraulic cylinder; 2-3-1. Outer ring; 2-3-2. Inner ring; 2-3-3. Spokes; 3-1. Stirring shaft; 3-2. Second motor; 4-1. Upper pipe; 4-2. Lower... Pipe, 4-3, intermediate pipe, 4-4, oil inlet pipe, 4-5, oil outlet pipe, 4-6, connecting plate, 5-1, powder feeding cylinder, 5-2, powder feeding shaft, 5-3, powder feeding motor, 5-4, adhesive powder hopper, 5-5, air inlet pipe, 5-6, powder dispersing plate, 6-1, asphalt spray pipe, 7-1, outlet, 7-2, three-way valve, 8-1, driven gear, 8-2, driving gear, 8-3, first motor, 8-4, hollow cylinder, 8-5, second bearing seat, 8-6, actuating rod, 9-1, mixing drum, 9-2, top cover. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] like Figure 1-6As shown, the method for controlling air pollution during rubber asphalt production according to the present invention is a three-stage treatment. The first stage is cooling and waste removal treatment: the fumes emitted during rubber asphalt preparation are collected and centrally treated. The fumes are collected using a negative pressure created at the collection hood 1-6 by an air pump and sent into the reaction vessel 1-1. The fumes are converted into dense bubbles by an array of air holes on the aeration pipe 1-4, which then pass through the cooling and cleaning liquid layer. While the fumes are cooled in the solution, some of the harmful substances inside are dissolved. The aeration pipe 1-4 can be set at the bottom of the reaction vessel 1-1, and multiple aeration pipes can be set.

[0019] Secondary treatment is plasma treatment: After primary treatment, the flue gas is dried by a dehumidifier and then enters plasma processors 1-3. A strong electric field is used to ionize oxygen molecules in the air to generate plasma, which is rich in high-energy electrons, ozone and free radicals. This plasma attacks the flue gas pollutant molecules, breaks their chemical bonds, and ultimately converts them into harmless small molecules such as CO2 or H2O.

[0020] The desiccant layer inside dehumidifiers 1-2 needs to be multi-layered. The first layer needs to remove tar from the flue gas, and coke, activated carbon, or ceramic fiber can be used. Subsequent desiccant layers can use silica gel or activated alumina as adsorbents to remove moisture from the flue gas, meeting the low dew point requirements of plasma equipment. Activated alumina is chosen because it has high adsorption capacity, good temperature resistance, high mechanical strength, and is not easily pulverized.

[0021] The third-level treatment focuses on controlling total emissions: the mixing drum is sealed, and a frustum-shaped mixing hood is installed inside the sealed mixing drum to achieve rapid and initial uniform mixing of asphalt and rubber powder. The asphalt is then rapidly heated with hot oil, and rotating mixing blades are used to perform high-speed shearing and mixing of the asphalt and rubber powder. The entire process reduces the time required for mixing and heating the rubber powder in the production process, thereby effectively reducing the emission of harmful fumes in terms of total emissions.

[0022] The plasma processor 1-3 employs planar electrodes connected to the radio frequency power supply 1-7. The surface of the planar electrodes is covered with a quartz glass layer. Asphalt fumes enter from one end of the plasma processor 1-3, are broken down by the plasma, forming numerous filamentary micro-discharge channels, and flow out from the other end, thus removing harmful components from the asphalt fumes. Both electrodes are completely encased in quartz glass. The quartz glass layer limits the unlimited growth of current, prevents the generation of thermal arcs, ensures uniform and stable discharge, and provides a smooth, easy-to-clean surface.

[0023] The plasma processors 1-3 adopt a dual-electrode parallel plate structure with radio frequency parameters of 5-8MHz, peak voltage of 0.7-12 kV, and electrode spacing of 2-4mm. The surface of the plate electrodes is covered with a quartz glass layer with a thickness of 0.5-3mm. Excessive thickness increases the high voltage required for electrode discharge, increasing energy consumption; insufficient thickness makes them susceptible to high-voltage breakdown and thermal arcing. Within the discharge channel, electrons gain extremely high energy and collide violently with gas molecules, generating not only ions and electrons but also a large number of active free radicals, excited-state molecules, and ultraviolet radiation, all of which can act on harmful components in the asphalt fume, removing them. The design is for treating asphalt fume with a concentration of 80-200 mg / m³, a processing capacity of 1000 m³ / h, and a temperature of 60°C. The designed asphalt fume purification efficiency is ≥95%, the VOCs removal efficiency is ≥90%, and the plasma processor power is 700-1000W. Figure 1 A pair of parallel electrodes is provided. If the flue gas treatment volume is large, multiple pairs of parallel electrodes can be set to treat more asphalt fumes.

[0024] The pollution control method of the present invention can employ the following device: the device includes a flue gas treatment section and a production control section. The flue gas treatment section includes a collection hood 1-6, a reaction vessel 1-1, a dehumidifier 1-2, and a plasma processor 1-3. The reaction vessel 1-1 is filled with a cooling cleaning liquid, and an aeration pipe 1-4 is provided at the bottom of the cooling cleaning liquid. The collection hood 1-6 is located above the stirring drum 9-1 and is connected to the aeration pipe 1-4 through a pipe. An air pump 1-5 is provided on the pipe. The flue gas discharged from the reaction vessel 1-1 flows sequentially through the dehumidifier 1-2 and the plasma processor 1-3 before being discharged.

[0025] The production control section includes a mixing drum 9-1 and a mixing section, a heating section, and a stirring section arranged sequentially from top to bottom inside it. The mixing section is equipped with a mixing cover 2-1, which is a frustum-shaped shell structure. It is mounted on a central shaft 2-2 and can rotate. The central shaft 2-2 is located on the upper cover 9-2 of the mixing drum 9-1. After the rubber powder and asphalt are initially mixed on the rotatable mixing cover 2-1, they flow downwards into the asphalt liquid.

[0026] In the production control section, a frustum-shaped mixing hood 2-1 forms a uniform thin layer of asphalt on its surface. Rubber powder is blown onto this surface and adheres to the asphalt layer, resulting in rapid initial mixing of the asphalt and rubber powder. The mixing hood is then immersed in the asphalt tank, carrying the asphalt with the adhered rubber powder into the tank. When the mixing hood 2-1 rises, a new thin layer of asphalt is formed. This process repeats continuously, accelerating the initial uniform mixing of the asphalt and rubber powder and preventing the agglomeration of the rubber powder that occurs during normal powder addition. The initially mixed asphalt-rubber powder enters the mixing zone, where rotating mixing blades perform high-speed shearing and mixing. Hot oil is used to heat the asphalt, ensuring more thorough mixing, shortening the mixing time, and reducing the total amount of emissions.

[0027] The cooling and cleaning solution in the reactor of this invention is an aqueous solution of NaOH or Na2CO3 with a concentration of 0.5-2%. It is mainly used for cooling and absorbing acidic gases in the flue gas, such as hydrogen sulfide, sulfur dioxide, some organic acids, and phenols, such as phenol and cresol. An aqueous solution of NaClO can also be used in the reactor to oxidize and decompose malodorous substances and some recalcitrant VOCs in the flue gas, and to remove dust. This invention incorporates an aeration pipe, utilizing an array of pores on the aeration pipe to convert the airflow into bubbles that pass through the solution layer, allowing for more thorough contact between the asphalt flue gas and the aqueous solution, resulting in a faster and more complete reaction and a better removal of harmful components.

[0028] In traditional rubber asphalt production processes, open mixing is commonly used, with asphalt fumes directly released into the air. Furthermore, the addition of rubber powder is typically done by pouring it in, which not only causes dust pollution but also leads to the tendency for rubber powder to agglomerate within the asphalt. To achieve thorough mixing, prolonged mixing time is necessary, further increasing fume emissions. This invention addresses this by employing the following design to achieve thorough mixing of rubber powder and asphalt within a closed space: The mixing cover 2-1 is provided with an upper support 2-3 and a lower support 2-4 at its top and bottom, respectively. The upper support 2-3 is a wheel structure with spokes, consisting of an outer wheel rim 2-3-1, an inner wheel rim 2-3-2, and spokes 2-3-3. The upper support 2-3 is rotatably mounted on the central shaft 2-2 through a central mounting hole. The lower support 2-4 has the same structure as the upper support 2-3. The upper cover 9-2 is provided with a guide hole that matches the central shaft 2-2. The upper end of the central shaft 2-2 passes through the guide hole and is connected to a hydraulic cylinder 2-7. The hydraulic cylinder 2-7 is mounted on the upper cover 9-2 and drives the mixing cover to move up and down through a piston rod, so that the mixing cover periodically completes the action of immersing in and detaching from asphalt.

[0029] The mixing hood 2-1 has a frustum-shaped shell structure, meaning it appears as a frustum from the outside. When the adhesive powder and asphalt are sprayed onto the conical surface of the frustum shell, it facilitates initial uniform mixing. The mixing hood 2-1, the central shaft 2-2, and the mixing drum 9-1 have overlapping central axes and are coaxially arranged. Figure 3 As shown, a first bearing seat 2-6 is provided in the mounting hole to enable reliable rotation of the upper bracket 2-3 on the central shaft 2-2. The lower bracket 2-4 is installed on the central shaft 2-2 with the same structure and installation method as the upper bracket 2-3.

[0030] A baffle plate can be installed on the top of the mixing hood 2-1. The baffle plate rotates with the mixing hood 2-1 to prevent asphalt and rubber powder from splashing upwards. A pressure relief hole can be installed on the mixing drum 9-1.

[0031] The rotation and drive settings for the mixing cover 2-1 can be configured as follows: A rotary drive assembly is provided on the upper cover 9-2, comprising a driven gear 8-1 and a driving gear 8-2. The driving gear 8-2 is mounted on the upper cover 9-2 through a driving shaft and is driven by a first motor 8-3. The first motor 8-3 is mounted on the upper cover 9-2, and the driving gear meshes with the driven gear. The driving shaft is mounted in the shaft hole of the upper cover 9-2 via bearing seats, and two bearing seats can be installed in the shaft hole. The number of teeth on the driven gear 8-1 is 1.5 to 5 times the number of teeth on the driving gear 8-2.

[0032] Below the upper cover 9-2 is a hollow cylinder 8-4. The central shaft 2-2 passes through the inside of the hollow cylinder 8-4. The driven gear 8-1 is mounted on the hollow cylinder 8-4 via the second bearing seat 8-5. A lever 8-6 is vertically arranged on the lower end face of the driven gear 8-1. As the mixing cover 2-1 moves up and down, the lever 8-6 can be movably inserted into or disengaged from the gap between adjacent spokes 2-3-3. When the mixing cover 2-1 moves to the upper position, the lever 8-6 is inserted into the gap between adjacent spokes 2-3-3, driving it to rotate. When the mixing cover 2-1 moves to the lower position, the lever 8-6 disengages from the gap between adjacent spokes 2-3-3, and the mixing cover stops rotating.

[0033] The number of spokes 2-3-3 can be selected as 3-5, and they are evenly distributed between the inner rim 2-3-2 and the outer rim 2-3-1; the number of actuating rods 8-6 is the same as the number of spokes 2-3-3 and their positional relationship is matched. The lower end of the actuating rod 8-6 is set as a cone to facilitate insertion. The actuating rod 8-6 plays the role of a clutch.

[0034] The rotation of the mixing hood 2-1 can also be achieved by the following method: the outlet direction of the asphalt nozzle 6-1 is biased towards one side of the mixing hood 2-1, and the asphalt sprayed by the asphalt nozzle 6-1 drives the mixing hood 2-1 to rotate.

[0035] The mixing hood (2-1) is covered with a thin plate. To further enhance the mixing effect of asphalt and rubber powder, conical protrusions (2-5) are evenly spaced on the surface of the thin plate. The conical protrusions 2-5 not only increase the contact area between asphalt and rubber powder, which is beneficial to the mixing of asphalt and rubber powder, but also, during the rotation of the mixing hood, the mixture of asphalt and rubber powder will be thrown outward along the conical protrusions under the action of centrifugal force, forming a raindrop effect. The raindrop-shaped asphalt is more conducive to the mixing of rubber powder.

[0036] The heating section is located in the middle of the mixing drum 9-1, between the mixing section and the stirring section.

[0037] The heating section includes an upper tube 4-1, a lower tube 4-2, and a middle tube 4-3. The upper tube 4-1 is arranged circumferentially around the inner wall of the stirring cylinder 9-1, forming a first circle, which is connected to the heat transfer oil heater through the oil inlet pipe 4-4. The lower tube 4-2 forms a second circle, which is connected to the oil outlet pipe 4-5. The diameter of the first circle is larger than that of the second circle. A connecting plate (4-6) is provided in the gap between the upper tube (4-1), the lower tube (4-2), and the middle tube (4-3), thereby forming a basket-shaped heating cylinder structure formed by the upper tube (4-1), the lower tube (4-2), the middle tube (4-3), and the connecting plate (4-6).

[0038] The mixture of asphalt and rubber powder is poured from the mixing hood and falls onto the wall of this cylindrical structure with an inverted cone shape, where it is quickly and evenly heated, preventing overheating and asphalt aging.

[0039] After the heat transfer oil is heated by the heat transfer oil heater, it is circulated through a high-temperature oil pump to form a complete circulating heating system. The initial temperature of the asphalt flowing in through the asphalt spray pipe 6-1 can be controlled between 160-175℃, the heating temperature of the heat transfer oil by the heat transfer oil heater should be controlled within the range of 190-200℃, and the temperature of the final heating section should be controlled within the range of 175-190℃. To prevent heat loss inside the mixing drum, an insulation layer can be installed outside the mixing drum 9-1. The insulation material can be glass wool or rock wool.

[0040] The mixing drum 9-1 is equipped with a rubber powder blowing section and an asphalt spray pipe 6-1; the discharge direction of the rubber powder blowing section and the asphalt spray pipe 6-1 is towards the mixing hood 2-1, and the head of the asphalt spray pipe 6-1 is equipped with a multi-hole nozzle.

[0041] The powder conveying unit includes a powder feeding cylinder 5-1, and a powder feeding shaft 5-2 installed inside the powder feeding cylinder 5-1. The powder feeding shaft 5-2 is equipped with a conveying screw and is driven by a powder feeding motor 5-3. The powder feeding cylinder 5-1 is provided with a feed inlet, which is connected to the powder hopper 5-4 through the feed inlet (a shut-off valve can be added here). A slanted high-pressure air inlet pipe 5-5 is connected to the powder feeding cylinder 5-1 near the outlet end. The angle between the air inlet pipe 5-5 and the axis of the powder feeding cylinder 5-1 is 30-35 degrees. The outlet of the powder feeding cylinder 5-1 is a funnel shape, and a powder dispersing plate 5-6 is provided inside the funnel shape. The powder dispersing plate 5-6 is conical, with its tip pointing towards the incoming material direction. The air outlet of the air inlet pipe 5-5 points towards the outlet end of the powder feeding cylinder 5-1. One end of the powder feeding shaft 5-2 is installed in a bearing housing inside the powder feeding cylinder 5-1. Two bearings spaced a certain distance apart can be installed in the bearing housing to ensure the stability of the powder feeding shaft 5-2 during rotation. The air inlet pipe 5-5 can be connected to a hot air furnace to preheat the adhesive powder during blowing.

[0042] The mixing unit includes a mixing shaft 3-1; the mixing shaft 3-1 is installed at the lower part of the mixing drum 9-1 and driven by a second motor 3-2. A first mixing blade and a second mixing blade are spaced apart on the mixing shaft 3-1; the first mixing blade 3-2 and the second mixing blade have opposite inclination angles, so that the material being mixed tumbles between the two mixing blades, thereby creating an up-and-down tumbling mixing effect on the asphalt and rubber powder, which is beneficial for the thorough mixing of the material. Both the first and second mixing blades consist of three blades, evenly arranged circumferentially along the mixing shaft 3-1. The first and second mixing blades can be rectangular blades bent at the desired angle.

[0043] To achieve circulating mixing and controllable quality, a three-way valve 7-2 is installed at outlet 7-1. One outlet of the three-way valve 7-2 flows towards the material consumption direction or the storage tank, and the other outlet flows towards the asphalt spray pipe 6-1. The purpose of circulation is: if the rubber powder or asphalt mixture is found to be unsatisfactory, it can flow back to the mixing drum 9-1, and the ratio of rubber powder or asphalt can be adjusted to continue mixing; of course, if the mixing is not sufficient, the asphalt can also be returned to the mixing drum 9-1 by controlling the three-way valve 7-2 to continue mixing.

[0044] The above describes the production process of mixing, heating, and stirring within a single mixing drum 9-1. Multiple mixing drums can also be set up for staged stirring, but a collection hood must be installed above each mixing drum to centrally treat the flue gas.

[0045] To improve the quality and performance of asphalt powder, an activator can be added during the mixing process. The activator can be rubber oil, added at a rate of 3-5 parts by weight of rubber oil per 100 parts of base asphalt. Rubber oil not only increases the stability of the asphalt-rubber powder mixture but also ensures the mixture's high rheological and aging resistance. Furthermore, to improve the softening point and penetration of asphalt, additives are added. These additives are styrene-butadiene rubber (SBR), montmorillonite, and sulfur. The addition rate is as follows: 2-3 parts SBR, 0.15-0.4 parts sulfur, and 3-4 parts montmorillonite powder per 100 parts of base asphalt. The SBR, montmorillonite, and sulfur are added to the hot-melt base asphalt, stirred at high speed, and aged at 130°C for approximately 1-3 hours. The additives of this invention increase the softening point and viscosity of asphalt, decrease penetration, enhance high-temperature stability and aging resistance, and simultaneously improve the low-temperature performance of asphalt.

Claims

1. A method for controlling air pollution during rubber asphalt production, characterized in that, The method employs a three-tiered governance approach, specifically including: The primary treatment is cooling and waste removal treatment: the fumes emitted during the preparation of rubber asphalt are collected and centrally treated. The fumes are collected by using a negative pressure formed at the collection hood (1-6) by an air pump. The fumes are sent into the reaction vessel (1-1) and the fumes are turned into bubbles by the air hole array set on the aeration pipe (1-4) and pass through the cooling and cleaning liquid layer. While the fumes are cooled in the solution, some of the harmful substances inside are dissolved. Secondary treatment is plasma treatment: After primary treatment, the flue gas enters the plasma processor (1-3) after passing through the dehumidifier. The strong electric field is used to ionize the oxygen molecules in the air to generate plasma, which is rich in high-energy electrons, ozone and free radicals. This plasma attacks the flue gas pollutant molecules, breaks their chemical bonds, and finally converts them into harmless small molecules such as CO2 and H2O. The third-level treatment involves controlling the total emissions: the mixing drum is sealed, and a frustum-shaped mixing hood is installed inside the sealed mixing drum to achieve rapid and initial uniform mixing of asphalt and rubber powder. The asphalt is then rapidly heated with hot oil, and rotating mixing blades are used to perform high-speed shearing and mixing of the asphalt and rubber powder. The entire process reduces the mixing time of rubber powder and asphalt in the production process, effectively reducing the emission of harmful fumes in terms of total emissions.

2. The method for controlling air pollution in rubber asphalt production according to claim 1, characterized in that, The plasma processor (1-3) uses a flat plate electrode, which is connected to a radio frequency power supply (1-7). The radio frequency parameters are set as follows: frequency 5-8MHz, peak voltage 0.7-12 kV, electrode spacing 2-4mm. The surface of the flat plate electrode is covered with a quartz glass layer with a thickness of 0.5-3mm. The asphalt fumes enter from one end of the plasma processor (1-3), are treated by the plasma, and then flow out from the other end.

3. The treatment device according to claim 1, characterized in that, The cooling and cleaning solution is an aqueous solution of NaOH or Na2CO3 with a concentration of 0.5-2%, used to cool the flue gas and absorb acidic gases in the flue gas, such as hydrogen sulfide, sulfur dioxide, some organic acids and phenols.

4. A treatment apparatus used in the method for treating air pollution in rubber asphalt production as described in any one of claims 1-3, characterized in that, The device includes a flue gas treatment section and a production control section; The flue gas treatment section includes a collection hood (1-6), a reaction vessel (1-1), a dehumidifier (1-2), and a plasma processor (1-3). The reaction vessel (1-1) is equipped with a cooling cleaning solution, and an aeration pipe (1-4) is installed at the bottom of the cooling cleaning solution. The collection hood (1-6) is located above the stirring drum (9-1) and is connected to the aeration pipe (1-4) by a pipe. An air pump (1-5) is installed in the pipe. The flue gas discharged from the reaction vessel (1-1) flows through the dehumidifier (1-2) and the plasma processor (1-3) in sequence before being discharged. The production control section includes a mixing drum (9-1) and a mixing section and a stirring section arranged sequentially from top to bottom inside it. The mixing section is equipped with a mixing hood (2-1), which is a frustum-shaped shell structure. It is mounted on a central shaft (2-2) and can rotate. After the rubber powder and asphalt are initially mixed on the rotating mixing hood (2-1), they fall downward into the asphalt in the mixing drum.

5. The treatment device according to claim 4, characterized in that, The mixing drum 9-1 is also equipped with a rubber powder blowing section and an asphalt spray pipe (6-1); the discharge direction of the rubber powder blowing section and the asphalt spray pipe (6-1) is towards the mixing hood (2-1).

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