Asphalt flue gas treatment plan for asphalt mixing plants

Current highway projects are generally large-investment projects. When carrying out actual project construction, it is very necessary to control the cost of the project. The production cost control and management of asphalt mixing stations in highway projects plays a huge role in controlling the cost of the entire highway project, because the main expenses of highway projects are concentrated on the mixing stations, and almost all the equipment used in highway projects Materials are closely related to the mixing station.

In today’s road construction, the use of a large number of road construction machinery represents the entry into the era of highway mechanization. For users, the goal is to use road construction machinery reasonably and tap its potential as much as possible. However, road construction machinery requires various accessories to work together. Now let’s take the asphalt mixing plant as an example to see what commonly used accessories and equipment are available.
Asphalt mixing plant equipment is a relatively complex system, which includes many equipment, mainly nine parts, namely: bag dust removal, finished material temporary storage warehouse, grading machine, fast heating asphalt tank, asphalt barrel removal machine, asphalt recycled material crushing and screening system, coal block crusher, coal mill and dust removal equipment, etc.

In recent years, asphalt pavement has dominated highway surfaces. With the rapid development of our country’s national economy, highway traffic volume is increasing, axle loads are increasing rapidly, vehicle speeds are increasing, and there are more and more quality problems occurring on asphalt pavements. Some are damaged after repair, and some have a service life of up to Less than design age. This has put forward increasingly higher requirements for the quality of asphalt pavement, and an important factor affecting the performance of asphalt surface layers is the gradation composition of the mixture. This article discusses the mix design of asphalt mixture.

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Due to certain restrictions on the current development status and conditions, the profits of the domestic asphalt pavement construction industry are getting lower and lower. Therefore, in the process of using asphalt mixing plants for production, on the one hand, the quality of the products and customer requirements must be ensured. , on the other hand, it is necessary to reduce production costs. Therefore, cost management is very important, and refined management should be implemented in this regard.
First, for device management. Since equipment is the foundation and key of production, in the cost management of asphalt mixing stations, the management of equipment plays an important role in reducing costs. Only by managing the equipment well can the normal working status be ensured, which provides the necessary guarantee for the smooth progress of the project. In fact, in today’s highway projects, equipment costs account for a large part of the cost and profit. The huge profits after the construction of a highway will be greatly affected by the management of materials and equipment.

Asphalt mixing plant is a very practical engineering machinery. Especially in the road construction process, it plays an irreplaceable role. Due to its importance, in addition to ensuring its own quality, the use and maintenance of the equipment must be carried out normally. Let’s learn about the daily maintenance requirements of asphalt mixing plants.

Asphalt mixing plant is one of the main equipment for producing asphalt concrete. It can mix asphalt, gravel, cement and other materials together in a certain proportion to obtain the products required for highway construction. In order to ensure its operating effect, the asphalt mixing plant also needs to be powered on for trial operation before it is officially put into work.
The first step in commissioning is to run a single motor and check whether the current, steering, insulation and mechanical transmission parts are operating normally. After confirming that each motor and mechanical transmission parts are operating correctly, conduct a joint trial run. During the entire process, it is necessary to conduct patrol inspections of key parts. If any abnormal noise is found, the cause should be identified and eliminated in a timely manner.

Due to its complexity and importance, asphalt mixing plants are more critical in road construction. Modern asphalt mixing stations have five key systems. Do you know what they are?
1. Mixing system of asphalt mixing plant
Mixing equipment is one of the key systems, why? Usually, the productivity of the mixing equipment has a great impact on the next step of construction efficiency. Most asphalt mixing plants use twin-shaft forced mixing. Since the drying drum and burner of the mixing equipment have strong overload capabilities, and in most cases, the moisture content of the mineral materials is less than 5%, this improves the productivity of the mixing equipment. provide conditions. The mixing blades of the mixer have an adjustable assembly angle and are driven by dual mixing shafts and dual motors.

Determining the material is a necessary stage in the design process of asphalt mixing equipment, and it is also one of the most critical links, because the material will be directly related to the use effect and service life of the entire equipment. Generally, when we determine the machine material, we usually base it on the characteristics of the working medium, and the same is certainly true for asphalt mixing equipment.

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.

Asphalt mixing stations are constructed according to a certain process, which can not only ensure the construction quality, but also ensure that the asphalt mixing station is not damaged. Although construction details are critical, the key skills of asphalt mixing station construction must be mastered.
Before the construction of the asphalt mixing plant, the top surface of the asphalt mixing station construction range should be removed, and the site elevation should be kept dry and flat to meet the design requirements. If the surface is too soft, the foundation should be reinforced to prevent the construction machinery from losing stability and ensure that the pile frame is vertical.
Then the on-site construction machinery should be inspected to ensure that the machinery is intact and assembled and tested under the premise of meeting the requirements. To ensure the verticality of the asphalt mixing plant, the deviation of the gantry guide and the mixing shaft from the verticality of the ground shall not exceed 1.0%. Asphalt mixer manufacturer.

Colored asphalt pavement is a kind of special pavement material that mixes colored particles into asphalt and then lays on the pavement

When we operate the asphalt mixing station, we should heat the equipment half an hour in advance, and the clear tank should be heated for at least two hours; and manually operate each part of the equipment to ensure that it is in good operation. status; it is also necessary to conduct relevant inspections on the valves and manually collect and return oil to ensure that the equipment can operate normally.
Several requirements for safe operation of asphalt mixing plants:

With the strengthening of the trend of environmental protection and energy conservation, the environmental protection of asphalt mixing plants has gradually become the mainstream form of mixing plant development. What kind of equipment can be called an environmentally friendly asphalt mixing plant? What are the basic conditions that must be met?
First of all, as an environmentally friendly asphalt mixing plant, it must meet the requirement of using less energy consumption during use. That is to say, under the conditions of the same quantity and quality, less energy is consumed during the operation process, including various resources such as water and electricity.
Secondly, environmentally friendly asphalt mixing plants not only require less energy consumption, but also must achieve higher production efficiency, while also reducing carbon emissions in the entire production process, so as to meet the proposed low-carbon production requirements.

Any kind of mechanical equipment must go through precise design, testing and other processes before it can be manufactured, and the same is true for asphalt mixing stations. According to the survey, the following stages are necessary for any asphalt mixing plant.
First of all, the main technical parameters of the product to be designed must be determined according to market needs, so construction market research, data analysis and other links are indispensable. Secondly, the ideal working principle and the plan to realize this principle will be determined through innovative conception and optimization screening. , a schematic diagram of the overall design scheme should also be given.

Certain failures cannot be avoided during the use of the asphalt mixing plant. For example, a malfunction of the cold material feeding device may cause the asphalt mixing plant to shut down. This may be due to a malfunction in the asphalt mixing plant or due to gravel or foreign matter being trapped under the cold material belt.

At present, the assembly and installation technology of large-scale asphalt concrete mixing equipment in high-grade highway construction is gradually improving. In order to improve work efficiency, it is necessary to analyze the pretreatment agent for the selection and matching of large-scale mixing equipment and auxiliary equipment, and clarify the installation and commissioning of asphalt stations. With the continuous change of highway construction methods, it is necessary to adopt production equipment according to the requirements of the development of the times. Intermittent asphalt mixing equipment is a widely used road construction equipment with the characteristics of simple operation and high work efficiency. Relevant staff are required to master the installation, construction and management methods of mixing equipment.

With the strengthening of the trend of environmental protection and energy conservation, the environmental protection of asphalt mixing plants has gradually become the mainstream form of mixing plant development. What kind of equipment can be called an environmentally friendly asphalt mixing plant? What are the basic conditions that must be met?
First of all, as an environmentally friendly asphalt mixing plant, it must meet the requirement of using less energy consumption during use. That is to say, under the conditions of the same quantity and quality, less energy is consumed during the operation process, including various resources such as water and electricity.
Secondly, environmentally friendly asphalt mixing plants not only require less energy consumption, but also must achieve higher production efficiency, while also reducing carbon emissions in the entire production process, so as to meet the proposed low-carbon production requirements

Asphalt mixing station is the standard for mixing asphalt. Having said that, many people still think that this has nothing to do with us. We don’t use asphalt, but do you know that our roads are made of asphalt? When I was a child, I used asphalt to pluck pig hair. The hair on the pig’s head was indeed clean. When using asphalt, it must be burned hot, because if it is cold, it will be very hard and cannot be used. Therefore, if a large amount of asphalt is needed, there must be an asphalt mixer because there is no more convenient equipment than it.
What kind of source material is asphalt that requires special equipment. Asphalt is a black-brown, high-viscosity organic liquid composed of hydrocarbons and non-metallic substances of different molecular weights. The surface is black and soluble in carbon disulfide. At the same time, it is also a waterproof, moisture-proof and anti-corrosion organic gelling material. It can be mainly divided into three types: coal tar asphalt, petroleum asphalt and natural asphalt. Asphalt is mainly used in industries such as coatings, plastics, rubber, and paving roads.

Asphalt mixing plant is a very practical engineering machinery. Especially in the road construction process, it plays an irreplaceable role. Due to its importance, in addition to ensuring its own quality, the use and maintenance of the equipment must be carried out normally. Let’s learn about the daily maintenance requirements of asphalt mixing plants.

The asphalt mixing plant is a complete set of equipment for mass production of asphalt concrete. The whole machine of the equipment consists of multiple systems, such as batching system, drying system, combustion system, powder supply system and dust prevention system. Each system is an important part of the asphalt mixing plant.
The working condition of the combustion system of the asphalt mixing plant has a great impact on the whole system, which is related to the economic efficiency of the whole system, temperature control accuracy and flue gas emission indicators. This article will briefly introduce how to judge the working condition of the combustion system of the asphalt mixing plant.
Generally speaking, due to the complexity of the detection equipment and methods, there are no conditions to achieve in the working process of most asphalt mixing plants. Therefore, it is more convenient to judge the working condition by a series of relatively intuitive factors such as the color, brightness and shape of the flame. This method is very simple and effective.

1. Causes of overflow
The main causes of spillage are:
1) Mixing materials in cold silo. Cold material warehouses generally have 5 or 4 warehouses. Each warehouse is required to contain pellets of a certain specification. If cold materials of different specifications are mixed or mistakenly loaded during the loading process, it will cause certain occurrences in a certain period of time. The shortage of pellets of one specification and the overflow of pellets of another specification can easily destroy the supply balance between hot and cold silos.

Asphalt mixing plant equipment is mainly composed of batching system, drying system, ignition system, hot material lifting, vibrating screen, hot material storage bin, weighing mixing system, asphalt supply system, granular material supply system, dust removal system, finished product hopper and automatic control system.
Components:
⑴ Grading machine
⑵ Vibrating screen
⑶ Belt vibrating feeder
⑷ Granular material belt conveyor
⑸ Drying mixing drum;
⑹ Coal powder burner
⑺ Dust removal equipment
⑻ Bucket elevator
⑼ Finished product hopper
⑽ Asphalt supply system;
⑾ Distribution station
⑿ Automatic control system.

Asphalt mixing plants are highly professional equipment with complex systems. It is inevitable that some failures will occur during use. So, what are the common hardware failures of asphalt mixing plants? Do you know?
(I) Because its system is relatively complex, when different components have problems, the problems caused may be different. If during the operation, it is found that the material addition of each silo is inaccurate, this problem may be due to the failure of the sensor of the asphalt mixing plant. At this time, the machine should be stopped for inspection and replaced with a new sensor if necessary. It may also be caused by the jamming of the scale bar. At this time, foreign objects should be removed in time.

[1]. Composition of intermittent asphalt mixing plant
The intermittent asphalt mixing plant mainly consists of cold material silo, cold material distribution system, cold material conveying system, combustion and drying system, ventilation and dust removal system, hot material elevator, vibrating screen, hot material silo, powder conveying system and asphalt conveying system. System, metering system, mixing cylinder, control system, finished material transportation and storage system, asphalt heating and insulation system, etc.
2. Discussing the phenomenon of warehouse cascading in asphalt concrete mixing plants
2.1 First, let’s introduce the structure and principle of vibrating screen. The main components include: RetentionRubber, SupportTube, vibrating screen drive system and supporting electrical components
The working principle is introduced as follows: hot aggregate is sent to the vibrating screen through the hot aggregate elevator, and the hot aggregate is vibrated and screened by the vibrating screen. Stones of different specifications enter their corresponding hot aggregate bins through the screen and cannot pass through the geotechnical work. The super-sized particles from the cloth screen enter the overflow bin and are sent out.

There is also a reversing valve in the asphalt mixer, which generally does not cause problems, so I have not understood its solution in detail before. But in actual use, we encountered this kind of failure. How should we deal with it?

The mixing speed of asphalt mixing plant equipment is indeed very fast, and the corresponding mixing power must be very high, but the specific amount must be measured in a certain way to determine the scope of use of asphalt mixing equipment. There are many methods to measure the mixing power of asphalt mixing equipment, but the relatively small errors are the motor counter-torque measurement method and the strain measurement method.
When the motor of the asphalt mixing equipment starts running, the electromagnetic moment acting on the motor rotor and the electromagnetic moment acting on the motor stator are equal, but their directions are opposite. Therefore, as long as the torque acting on the stator is measured, the torque on the rotor can be obtained, and the actual mixing torque is obtained after deducting the friction torque on the rotor bearing.
On the premise of knowing the torque and mixing speed, the mixing power of the asphalt mixing equipment can be calculated. This is the so-called motor counter-torque measurement method, which is relatively simple and suitable for smaller mixing systems.

In order to keep the asphalt mixing plant in a stable operating process, a series of adverse factors related to it must be excluded. What should be paid attention to in this process?
First of all, the selection of the delivery pump in the asphalt mixing plant must meet the requirements of asphalt pouring per unit time during construction, height, and horizontal distance requirements. At the same time, there must be a certain technical and production capacity reserve, and the balanced production capacity is preferably 1.2 to 1.5 times.
Secondly, the movement and hydraulic systems of the asphalt mixing plant must be normal, and there must be no abnormal sound and vibration to avoid large aggregates and lumps inside the equipment, otherwise it is easy to get stuck at the feed inlet of the mixing plant or be blocked due to arching. Another point is that when the asphalt mixing plant is in the same site, it is not suitable to use too many pumps and pumps from multiple manufacturers to avoid affecting its normal operation.

The drying and heating system of the asphalt mixing plant can be regarded as an important part of the whole, so in actual work, it treats the material in a countercurrent heating manner, thereby achieving full dehydration of the cold aggregate, and heating it to a certain temperature, thereby providing the necessary conditions for the normal and continuous operation of the asphalt mixing plant.
During the entire heating process of the asphalt mixing plant, the main purpose is to make the performance of the mixture more in line with the requirements of use, and to make the finished material have good paving performance. Under normal circumstances, the heating temperature of the aggregate is about 160℃-180℃.

The quality of the asphalt mixing plant will be a key factor affecting the quality of the project. After reviewing relevant materials related to the production and construction of asphalt concrete, we summarized some cases of failures in asphalt concrete mixing stations during construction and analyzed the reasons.
1. Unstable output and low production efficiency of asphalt mixing plants
(1) Improper proportioning. The mix ratio of asphalt concrete is divided into target mix ratio and production mix ratio. Among them, the target mix ratio controls the cold material transportation ratio of sand and gravel materials, and the production mix ratio is the mixing ratio of various types of sand and stone materials in the finished asphalt concrete materials specified in the design. The production mix ratio is determined by the laboratory, which directly determines the off-site grading standard of the finished asphalt concrete. The target mix ratio is set to further ensure the production mix ratio, and can be adjusted appropriately during production according to the actual situation. When the target mix ratio or the production mix ratio is not appropriate, the stones stored in each measurement of the asphalt mixing station will be disproportionate, with some overflowing and some other materials, unable to be weighed in time, and the mixing cylinder will be idling, resulting in reduced output.