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Asphalt flue gas treatment plan for asphalt mixing plants

Asphalt flue gas treatment methods, their principles and characteristics, and an asphalt flue gas environmental protection treatment plan based on the actual asphalt flue gas problems faced by the unit.

1. Basic situation
My unit’s mixing plant is equipped with a 4000-type asphalt mixing plant. During daily production of the asphalt mixing plant, a large amount of asphalt smoke will be emitted from the mixing pot discharge port. This smoke not only has an unpleasant smell, but also contains A large number of compounds that are harmful to the human body, such as benzopyrene, benzanthracene, carbazole and other polycyclic aromatic hydrocarbons, mostly have carcinogenic risks. Smoke overflow will cause pollution to the surrounding atmospheric environment and affect the personal health of workers. Although the overflow port of the mixing station is equipped with a dust retaining wall, the fine dust is seriously raised, and the cold material belt conveyor is dusty. In order to protect the environment, reduce pollution, and reduce cost investment, based on full research and absorption of technology in the same industry, and combined with the actual situation of asphalt mixing, we are planning to install asphalt mixing bag dust collectors to the flue at the discharge port of the mixing pot to control asphalt fumes. Gas is processed. The dust removal efficiency of the bag dust collector can reach 97%~99%, and the dust-containing gas can be purified to a level of 50mg/Nm3.

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Asphalt flue gas treatment methods, their principles and characteristics, and an asphalt flue gas environmental protection treatment plan based on the actual asphalt flue gas problems faced by the unit.

1. Basic situation
My unit’s mixing plant is equipped with a 4000-type asphalt mixing plant. During daily production of the asphalt mixing plant, a large amount of asphalt smoke will be emitted from the mixing pot discharge port. This smoke not only has an unpleasant smell, but also contains A large number of compounds that are harmful to the human body, such as benzopyrene, benzanthracene, carbazole and other polycyclic aromatic hydrocarbons, mostly have carcinogenic risks. Smoke overflow will cause pollution to the surrounding atmospheric environment and affect the personal health of workers. Although the overflow port of the mixing station is equipped with a dust retaining wall, the fine dust is seriously raised, and the cold material belt conveyor is dusty. In order to protect the environment, reduce pollution, and reduce cost investment, based on full research and absorption of technology in the same industry, and combined with the actual situation of asphalt mixing, we are planning to install asphalt mixing bag dust collectors to the flue at the discharge port of the mixing pot to control asphalt fumes. Gas is processed. The dust removal efficiency of the bag dust collector can reach 97%~99%, and the dust-containing gas can be purified to a level of 50mg/Nm3.

2. Purification plan
The main component of asphalt flue gas is tar fine mist particles with a particle size of 0.1-1.0 μm. The main task of asphalt flue gas treatment is to treat these tar fine mist particles so that they are not discharged into the air and reduce as much as possible the effect on the environment. In addition, we also investigated the treatment of asphalt flue gas, mainly using the induced air dust removal method and the exhaust gas photooxygen catalytic activated carbon adsorption method.
The methods to control asphalt flue gas are as follows:
1. Induced air dust removal method:
A flue is installed at the mixing pot discharge port and the stone overflow port. The asphalt fumes generated during production and the dust generated during discharging are directly extracted with an induced draft fan, and filtered through bag dust removal to achieve pure emissions. (The dust raised by the cold material belt conveyor can be treated by a single machine for dust removal)
2. UV photooxygen catalysis and activated carbon exhaust gas treatment equipment
It is a special treatment and purification equipment for removing organic waste gas and malodorous gas. It uses high-energy ultraviolet beam irradiation to decompose organic (malodorous) waste gas, such as ammonia, trimethylamine, hydrogen sulfide, methyl mercaptan, carbon disulfide, styrene, benzene, and other VOCs. The molecular chain structure of organic-like odor gases causes them to degrade and transform into low-molecular compounds, such as CO2, H20, etc.; because high-energy ultraviolet beams decompose oxygen molecules in the air to produce active ozone, because ozone has a strong oxidizing effect on organic matter, and It has an immediate removal effect on malodorous gases and other irritating odors. At the same time, the catalytic layers (nano titanium dioxide) on both sides of the lamp generate superoxide anions and hydroxyl radicals with strong chemical activity when exposed to ultraviolet light, which can degrade organic matter and effectively decompose toxic and harmful substances in odorous gases and deodorize As a result, the decomposed odorous gas can be discharged harmlessly without causing secondary pollution. At the same time, it can achieve efficient disinfection and sterilization, and then be discharged to the outdoors through the exhaust duct;

3. Flue gas dust removal and purification system technology
The entire flue gas treatment device includes two parts: flue gas collection and flue gas absorption.
In view of the characteristics of asphalt smoke and dust at the overflow port during the asphalt mixing production process, it is necessary to install a dust collection hood at the discharge port of the mixing pot. The dust collection hood is semi-enclosed, which greatly reduces the overflow of asphalt smoke. In addition, after the asphalt material is loaded into the vehicle, some of the smoke will overflow from the vehicle. Therefore, it is necessary to make a smoke hood and extend the dust collector to the front end of the vehicle to recover all the asphalt smoke as much as possible.
Induced air dust removal and UV photooxygen catalytic activated carbon method
The asphalt mixing station mixing pot discharge port is equipped with a flue for cleaning asphalt smoke and dust. The asphalt flue is connected to the dust removal flue, and the asphalt flue gas is filtered and discharged through bag dust removal.
1. Key points of system design
First, a dust collecting cover must be installed under the mixing pot to semi-close the unloading port to prevent smoke and dust from overflowing. Secondly, pipes must be installed in the overflow port dust and dust collection hood. The main component of asphalt flue gas is tar fine mist particles with a particle size of 0.1-1.0 μm. During the production process, the asphalt flue gas enters the dust removal flue through the pipeline. There is a large amount of dust-containing gas in the flue. The dust in the dust-containing gas will combine with the tar fine mist particles in the asphalt flue gas. After combined with geothermal power generation, it will be filtered by bag dust removal. The clean gas is discharged through the induced draft fan.
2. Process
(1) Dust collection cover for asphalt smoke at the mixing pot discharge port and overflow port → bag dust removal → UV light oxygen activated carbon waste gas treatment → induced draft fan
(2) Belt conveyor drop dust collector → bag dust collector → induced draft fan

4. Conclusion
Protecting the ecological environment is related to the fundamental interests of the broad masses of the people and the long-term interests of the development of the Chinese nation. It is a cause that benefits the present and will benefit the future. Only by being deeply aware of the profound significance of the environment to people’s development can we take practical actions to protect the environment and have blue skies, clear waters, green mountains, and green spaces. By constantly meeting environmental protection requirements, we can promote technological upgrading of enterprises, thereby obtaining economic benefits and A win-win situation for social benefits.

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    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.

    The drying drum of the asphalt mixing plant should pay attention to daily inspection, correct operation and reasonable maintenance, so as to extend its service life and reduce the cost of engineering use.
    1. Pay attention to daily inspection. Before the asphalt mixing plant officially works, the drying drum needs to be tested and inspected to see whether each pipeline is reliably connected, whether the lubrication of the whole machine is feasible, whether the motor can be started, whether the functions of each pressure valve are stable, whether the instrument is normal, etc.
    2. Correct operation of the mixing station. At the beginning of the asphalt mixing plant, manual operation can only switch to automatic control after reaching the specified production capacity and discharge temperature. The aggregate should be dry and have a standard mode so that it can maintain a constant temperature when flowing through the drying drum. When the entire aggregate is sent to dry, the moisture content will change. At this time, the burner should be used frequently to compensate for the change in moisture. During the rolling stone processing, the amount of water directly formed is basically unchanged, the amount of combustion accumulation increases, and the amount of water in the deposited accumulation material may change.
    3. Reasonable maintenance of the asphalt mixing plant. Aggregates should be deactivated when the asphalt mixing plant is not in operation. After work every day, the equipment should be operated to discharge the aggregate into the dryer. When the material in the hopper leaves the combustion chamber, the combustion chamber should be closed and allowed to idle for about 30 minutes to cool down, so as to reduce its impact or make the machine run in a straight line. Install the drying cylinder fixing ring on all rollers synchronously.

    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.

    Asphalt concrete, as the name implies, is a composite material formed by combining asphalt and concrete. Its main components usually include three categories, aggregate, filler and asphalt. Aggregate, as the basic skeleton of asphalt concrete, is mainly composed of crushed stones of different sizes. These crushed stones are carefully selected and proportioned to ensure the strength and stability of asphalt concrete. Filler usually refers to fine-grained materials such as stone powder, which are filled between crushed stones to increase density and improve overall strength. Asphalt is a binder that can tightly bond aggregate and filler together to form a solid whole. In the process of producing asphalt concrete, the proportion of various raw materials will be adjusted according to different formulas. These formulas are usually formulated according to the specific requirements of the road and the use environment to ensure that asphalt concrete can meet various complex road conditions. The place where this composite material is produced is a special asphalt mixing plant. This is an asphalt concrete mixing plant. The large trucks that we see every day to transport asphalt concrete come out from here. In the asphalt mixing plant, the entire production process is finely divided into multiple steps.
    First, workers use loaders to deliver aggregates into cold silos. Cold silos are usually divided into several different chambers according to the size of aggregate particles, and each chamber corresponds to aggregates of different specifications. In this way, in the subsequent mixing process, the proportion of various aggregates can be accurately adjusted according to customer needs.
    Next, these aggregates will be sent to the drying drum through a vibrating feeder and a belt conveyor. In the drying drum, the aggregates will be heated to a specified temperature by the high-temperature heat source provided by the burner. During this process, the spiral blades and sheep feed plates inside the drum will ensure that the aggregates are fully heated during rotation and remove the moisture in them. In this way, not only can the bonding strength between aggregates and asphalt be improved, but also the stability and durability of asphalt concrete after paving can be ensured.

    In highway construction, asphalt mixing station plays a vital role. As a kind of equipment integrating intelligence, high efficiency and environmental protection, asphalt mixing station provides strong support for improving the quality of highway construction. This article will introduce the relevant knowledge of asphalt mixing station in detail to help readers understand this key equipment.
    Asphalt mixing station is a kind of equipment specially used for producing asphalt concrete, which is widely used in highway, municipal road, bridge and other engineering construction. Asphalt concrete is a kind of building material mixed with asphalt, gravel, sand and other materials. It has the characteristics of strong durability and good compressive resistance. It is an ideal material for highway construction.
    2. Features
    Intelligence: Asphalt mixing station is equipped with advanced control system and sensor, which can realize automatic production, reduce manpower input and improve production efficiency.
    Environmental protection: Asphalt mixing station adopts closed design to reduce dust pollution, and is equipped with noise reduction facilities to reduce noise pollution.
    Efficiency: Asphalt mixing station has high production capacity and can produce a large amount of asphalt concrete in a short time to meet the needs of engineering construction.
    3. Function
    Provide asphalt concrete: The main function of asphalt mixing station is to produce asphalt concrete and provide necessary building materials for highway construction.
    Improve highway quality: By using asphalt concrete, the smoothness, compressive strength and durability of the highway can be improved, thereby improving the quality of the highway.