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Selection of treatment technology for asphalt smoke produced by asphalt mixing plants

In recent years, asphalt concrete, as a new green building material, is gradually being valued by people because of its excellent performance in saving resources, being environmentally friendly, ensuring the quality of construction projects, and achieving sustainable utilization of resources. The development of asphalt concrete fully embodies my country’s policies to achieve energy conservation and emission reduction, and is also an important measure to promote the development of circular economy.

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In recent years, asphalt concrete, as a new green building material, is gradually being valued by people because of its excellent performance in saving resources, being environmentally friendly, ensuring the quality of construction projects, and achieving sustainable utilization of resources. The development of asphalt concrete fully embodies my country’s policies to achieve energy conservation and emission reduction, and is also an important measure to promote the development of circular economy.
1. Asphalt smoke
Asphalt smoke refers to the hydrocarbon organic particulate matter emitted during the production process of petroleum asphalt and asphalt products and a small amount of gaseous hydrocarbon matter under normal temperature conditions. It is a mixed flue gas containing complex chemical substances, and the main component is a hydrocarbon mixture. , among which there are many polycyclic aromatic hydrocarbons. Asphalt smoke contains polycyclic aromatic hydrocarbons such as benzopyrene, a strong carcinogen. Polycyclic aromatic hydrocarbons in the atmosphere are an important cause of the rise in respiratory cancers. Pure benzopyrene is a yellow needle-shaped crystal with a boiling point of about 310°C and a melting point of 179°C. It is insoluble in water and slightly soluble in alcohol. It is a strong carcinogen and can cause skin cancer. In asphalt smoke, it easily adheres to the particle size For particles below 8.0um.
The asphalt required for asphalt concrete production is pre-stored in an asphalt storage tank. When the servo motor is tested and used, it needs to be heated and melted by a thermal oil furnace, and then pumped into the asphalt mixing tank with an asphalt pump to mix with a certain proportion of gravel. After the asphalt is heated Asphalt fumes will be generated during the mixing process. If the traditional bag dust collector is used, the asphalt will stick to the bag, causing the bag to be clogged. The multi-tube cyclone dust collector will have poor removal efficiency of asphalt smoke.
2. Current methods for treating asphalt flue gas
(1) Incineration method The composition of asphalt smoke is complex, but it is basically hydrocarbons and can burn under high temperature conditions. Asphalt flue gas is directly introduced into a special heating furnace for incineration. Under a certain time and temperature, it can be completely burned when in contact with air. Even smoke mixed with a small amount of carbon particles can be burned when the temperature reaches above 900°C. When treating asphalt smoke by incineration, the higher the concentration of asphalt smoke, the more advantageous it is. However, when dealing with low-concentration asphalt smoke produced by asphalt concrete mixing, household coal-fired heating boilers require external energy as supplementary fuel for the asphalt smoke, and the combustion temperature needs to be adjusted. and strict control of time, the processing energy consumption is too high, the transportation cost is high and uneconomical.
(2) The electrostatic capture method uses electrostatic capture of asphalt smoke on the same principle as the electrostatic precipitator. The asphalt smoke is sent into the electric field through the induced draft fan, and the asphalt smoke is discharged between the anode and cathode with the help of corona discharge. The smoke particles are charged and adsorbed on the plate to achieve the purpose of separating asphalt smoke and gas. Dry electric traps have extremely low efficiency in capturing gas phase components, while wet electric traps can capture gaseous asphalt, but wet electric traps produce electrocapture wastewater, which brings secondary pollution.
(3) Absorption method It utilizes the different solubilities of various mixed components in asphalt flue gas in the absorbent, or the reaction of active components in the absorbent with certain components to achieve the purpose of treating asphalt flue gas. Gasoline, diesel and other substances are generally used for absorption. This method has low system resistance, low energy consumption, simple equipment, and easy maintenance, but the purification rate is not high, it is flammable, and it is not easy to use;
(4) Adsorption method It is a process that uses an active substance with a large specific surface as an adsorbent to physically adsorb asphalt flue gas, and then regenerates the adsorbent for reuse. This method has simple process, high purification efficiency, and low investment and operating costs. According to the properties of asphalt smoke and the comparative analysis of the above methods, it is recommended to use adsorption method to treat asphalt smoke exhaust gas, and use activated carbon to physically adsorb the asphalt smoke. The removal efficiency of benzopyrene and asphalt smoke reaches over 99.5%. After the asphalt oil fumes are treated to meet the standards, they will be discharged through an exhaust pipe of no less than 15 meters.

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    More Asphalt Processing

    For road construction machinery, the following is mainly about the asphalt mixer in road construction machinery equipment. Because it is the key product of Wuxi road construction machinery manufacturers, it is necessary to carry out comprehensive training and mastery, so as to ensure meticulousness and practicality, and not ignore any knowledge points.
    1. In road construction machinery, is there any difference between asphalt mixing equipment and asphalt concrete mixing equipment?
    The answer given by Sinoroader Group manufacturer to this question is no, that is, there is no difference between asphalt mixing equipment and asphalt concrete mixing equipment. They refer to the same type of equipment, but they are different in name. It can be said that they are two names for the same type of equipment, and there is no difference in essence.
    2. During the operation of the asphalt mixer, there is a sound in the mixing pot. What’s the matter?
    In the view of Sinoroader Group, there are two answers to this question. One is that the mixer arm on the asphalt mixer is not good or damaged. The second is that the wear-resistant lining in the mixer is damaged, which leads to this problem.
    3. What are the dust removal devices in the asphalt mixing equipment?
    In the asphalt mixing equipment, for its dust removal device, Sinoroader Group believes that the key is to use the dry ash removal method, because it can facilitate the collection of raw materials. In terms of its dust removal equipment type, there are filter dust removal equipment, centrifugal fan dust removal equipment and force dust removal equipment, etc., which can all be used well.
    For the asphalt mixer and asphalt mixing equipment in road construction machinery, I believe that through the practical discussion of the above relevant content, everyone can master it well and master it, so that in practice, they can have new gains and benefit a lot from it.

    The materials used in asphalt mixtures contain a lot of dust. When the equipment is operating, if the dust enters the atmosphere, it will cause pollution. Therefore, dust removal equipment must be installed, and now bag dust removal is the main method. Safety is a common sense issue. There are well-established standard safety rules.
    Do not clean, oil or adjust any mechanical equipment that is not specifically explained during operation; turn off the power and lock it before inspection or repair activities to prepare for accidents. Because each situation has its own particularity. Therefore, be vigilant about safety damage issues, incorrect operation issues and other deficiencies. All of them may lead to accidents, personal injuries, reduced production efficiency, and more importantly, loss of life. Careful and early prevention is the best way to avoid accidents.
    Careful and correct maintenance can make the equipment work more efficiently and control it within a certain level of pollution; the maintenance of each component should be carried out according to its operating standards; maintenance plans and safe operation procedures should be formulated according to the inspection and repair conditions that must be carried out.
    Take out a work log to record all inspection and repair conditions, list the analysis of each inspection of each component and the description of the repair content or the date of the repair; the second step is to give the inspection cycle for each component, which should be determined according to the service life and wear condition of each component.

    The asphalt mixing equipment mentioned here may also refer to an asphalt concrete mixing plant. At present, asphalt mixing equipment generally uses a complete set of equipment for mixing. So what are the benefits of using a complete set of equipment?
    1. More effective.
    In today’s industrial production, a complete set of asphalt mixing equipment can help improve production efficiency and ensure product quality. This is why even in a mixing plant, the equipment used is a complete set of equipment.
    2. Ensure quality.
    When mixing asphalt, a certain ratio is set. For this type of asphalt liquid used in different occasions, its ratio control has strict requirements. It is necessary to determine its mixing method and mixing time to ensure that the asphalt liquid is consistent with the production site. One of the advantages of a mixing plant is that the quality can be effectively controlled.
    3. It can be sampled.
    After mixing at the mixing plant, the quality inspector can sample and inspect to ensure that the mixed asphalt liquid meets the use requirements.
    In short, asphalt mixing equipment will use a complete set of equipment, mainly to facilitate the later asphalt to meet production needs. Through the mixing plant, the mixing time and feeding sequence can be better controlled, so that the mixed product can meet different use requirements. And after using the archiving equipment, effective spot checks can be carried out, which can better ensure that the quality meets the construction requirements.

    The actual operation steps of drying drum of asphalt mixing equipment: 1. Pay attention to routine inspection; 2. Proper operation steps; 3. Effective maintenance.
    Drying drum is a cylindrical device specially used for heating and drying stones in asphalt mixing equipment. Proper application and maintenance of drying drum can maximize the performance of drying drum, increase its service life and reduce application cost. Let’s take a look at the actual operation steps below.
    1. Pay attention to routine inspections
    The asphalt mixing equipment drying drum has been tested and inspected before leaving the factory, but it will be subjected to vibration and vibration during transportation to the construction site. A comprehensive inspection should be carried out before use: check whether all anchor bolts are tightened; whether all key pins are properly driven; whether all drive devices are adjusted according to the manufacturer’s instructions; whether all pipe connections are appropriate and whether the three-way joints are reliable; whether the entire equipment is fully lubricated; start the motor and check whether all parts can rotate steadily in the correct rotation direction; whether the pressure gauge can work normally and whether the valve is adjusted to the correct working pressure; whether the burner ignition mechanism is available and whether the gate valve is open.
    2. Correct operation steps
    After the equipment is started, it is recommended to control the machine manually at the beginning, and then switch to the automatic control mode after achieving the required production volume and pouring temperature. The stone should be dried and have a stable moisture content as much as possible so that the stone can maintain a stable final temperature when passing through the drying drum. If the stones delivered to the drying drum change frequently and the moisture content changes each time, the burner should be adjusted frequently to compensate for these changes.
    The stones directly from the crushed stone have a relatively constant moisture content, while the stones from the outdoor storage yard have a higher moisture content, and the moisture content of different piles varies greatly. Therefore, it is best for the stones to come from the same source.