Environmental conditions and functional requirements of asphalt mixing plants

We know that the first priority in production is to ensure safety. In the process of operating equipment, staff must always pay attention to using the correct operating methods. Regarding the asphalt mixing plant, it is used to produce asphalt mixtures, modified asphalt mixtures, and colored asphalt mixtures to meet the needs of highways, graded highways, municipal roads, airports, etc.

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 station also needs to be powered on for trial operation before it is officially put into work.
At the beginning of the test run, first run a single motor, and at the same time 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.

Modified Bitumen

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.

Asphalt (composition: asphaltenes and resin) tanks are divided into: intermittent and continuous functions according to the production process: initial batching of aggregates, heating and drying, screening and measurement; heating and insulation of asphalt (composition: asphaltene and resin) , transportation and measurement; transportation and measurement of filler; uniformly mix the measured aggregate, asphalt (composition: asphaltene and resin), and filler into a finished product of a certain temperature.

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.

In the 21st century, with the booming development of modern engineering construction, complex integrated supporting equipment has been invested in large quantities. Its complex process and more independent operating components have relatively high requirements for the performance of its equipment control system. The application of PLC in asphalt mixing station realizes the control of the entire process of asphalt mixing station, which facilitates the construction of modern engineering construction. Therefore, this article discusses and analyzes the application of PLC in asphalt mixing station, which has certain economic value and practical significance.

The plug valve is a rotary valve in the shape of a closure or plunger. After rotating 90 degrees, the channel opening on the valve plug is the same as or separated from the channel opening on the valve body to complete opening or closing. It is widely used in oilfield excavation, transportation and refining equipment, and such valves are also needed in asphalt mixing plants.
The valve plug of the plug valve in the asphalt mixing plant can be cylindrical or conical. In the cylindrical valve plug, the channel is generally rectangular; in the conical valve plug, the channel is trapezoidal. These shapes make the structure of the plug valve light and very suitable for blocking and connecting media and diversion.

Judging from the situation of highways in our country, asphalt pavement is the most used, which is one of the reasons why asphalt mixing plants have developed so rapidly. Under the situation of rapid economic development, the quality problems of asphalt pavement are gradually increasing, which puts forward higher and higher requirements for the quality of asphalt. It is understood that the primary factor that affects the quality of asphalt is the ratio of raw materials. This is also covered in the introduction of asphalt mixing stations. You can discuss it together.
In order to obtain high-quality asphalt products, in addition to the asphalt mixing equipment meeting the requirements, selecting the appropriate asphalt mixture gradation type is also a top priority. According to my country’s current regulations, the maximum particle size of the asphalt mixture in the upper layer of the highway should not exceed half of the layer thickness; while the maximum particle size of the aggregate in the middle surface layer of asphalt mixture should not exceed two-thirds of the layer thickness; and the asphalt layer should not exceed half of the layer thickness. The maximum nominal aggregate size of the pavement structural layer mixture should not exceed one-third of the layer thickness.
Based on this analysis, if an asphalt surface layer with a certain thickness is selected according to the above specifications, the particle size of the asphalt mixture aggregates will generally be larger, which will inevitably bring insurmountable construction difficulties to the construction of asphalt concrete pavement. After investigation, testing, analysis, and comparison, it can be seen that the lower layer has a wider choice, so the AG-201 gradation type can be used; while the selection of the upper layer mixture type is more difficult, and it is necessary to achieve a reasonable choice of this mix ratio. , on the one hand, we must examine as many aggregate resources as possible, and on the other hand, we must also consider the model of the mixing equipment.
In order to ensure the quality of the project, strict selection and inspection of engineering materials must be carried out. Therefore, the selection and determination of raw materials should be based on the requirements for pavement structure and use quality, combined with the supply of floor materials, and inspection in accordance with the requirements of relevant test procedures, and then Select the best materials so that all technical indicators of the materials meet the specified technical requirements.

[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.

Asphalt concrete mixing equipment generally uses conveyor belt conveyors to transport cold materials. Its main advantages are large conveying capacity, continuous operation, simple equipment structure and automatic control. However, belt deviation is a common fault, which directly affects the drying operation of the drying drum and also affects the production efficiency of the mixing equipment. Therefore, it is very important for the asphalt mixing station to solve the belt deviation problem at the operation site of the asphalt concrete mixing equipment.

Judging from the current situation of domestic highway construction, asphalt mixing stations will also achieve great development for a long time to come. This is also a result of rapid economic development. However, we have found that more and more quality problems occur when constructing asphalt pavements in modern times. Therefore, we have to put forward more stringent requirements for the quality of asphalt.

When using the asphalt mixing plant, you should regularly check the fuel pressure regulating valve or pressure reducing valve to determine whether the surface of the locking nut on the adjustable bolt is clean and removable; if the surface of the screw or nut is too dirty or rusty, it needs to be repaired or Replace the regulating valve.
Check the oil pump regularly to determine whether the sealing device is intact and whether the internal pressure is stable, and replace any damaged or leaking sealing devices. When using hot oil, check whether all oil pipes are well insulated. The filter installed between the oil tank and the oil pump must be cleaned regularly and checked for excessive wear to ensure that the fuel reaches the oil pump smoothly from the oil tank and to reduce the possibility of potential component failure.

In fact, asphalt mixing stations are not uncommon in our daily lives. They are mainly a unit of equipment specially designed to mix asphalt. What we really don’t understand is the gas system of the asphalt mixing station. Only correct maintenance And operation can bring out the best production effect. So what are the faults in the gas circuit of asphalt mixing station?
The following three points are the more common gas path failures of asphalt mixing stations:

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 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.

There is also a reversing valve in the asphalt mixing plant, which generally does not cause problems, so I have not understood its solutions in detail before. But in actual use, we encountered this kind of failure. How should we deal with it?
The failure of the reversing valve of the asphalt mixing station is not complicated, that is, the reversing is not timely, gas leakage, electromagnetic pilot valve failure, etc. The corresponding causes and solutions are of course different. For the reversing valve to not change direction in time, it is generally caused by poor lubrication, the spring is stuck or damaged, oil dirt or impurities get stuck in the sliding part, etc. For this, it is necessary to check the status of the lubricator and the quality of the lubricating oil. Viscosity, if necessary, the lubricant or other parts can be replaced.
After long-term use, the reversing valve is prone to wear of the valve core sealing ring, damage to the valve stem and valve seat, resulting in gas leakage in the valve. At this time, the sealing ring, valve stem and valve seat should be replaced, or the reversing valve should be replaced directly. In order to reduce the failure rate of asphalt mixers, maintenance must be strengthened on a daily basis.

Speaking of asphalt mixing plants, we are not unfamiliar with them. This is a unit equipment specially used for asphalt mixing. In fact, what we really lack understanding of is its gas system. Even the accumulated failures that often occur in the gas system of asphalt mixing plants are not very clear. Facts have proved that only by properly maintaining the various systems of the equipment can efficient production and good benefits be achieved.
The following are four types of gas system failures that often occur in asphalt mixing plants. Let’s analyze the causes of the problems behind the failures one by one.

Due to raw materials or usage, asphalt mixing plants will be subject to a certain degree of wear or other failures during daily use. If they are not controlled or repaired in time, the problem will be further exacerbated. For asphalt mixing plants, what are the ways to prevent wear and failure?
If the asphalt mixing plant is not treated in time after being worn, it may corrode once it is in contact with air, rainwater, etc. for a long time. If the parts of the asphalt mixing plant are severely corroded, the service life and normal operation of the entire equipment will be affected.

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.

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.

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.

The driving device is one of the important components of the asphalt mixing plant, so whether it can operate reliably must be highly valued to avoid adverse effects on the entire asphalt mixing plant. In order to ensure that the driving device in the asphalt mixing plant is indeed complete and reliable, the following maintenance measures are essential.

Oscillating screen. It can screen the heated aggregate according to the design. It requires fully enclosed, double oscillating motor replacement (replacing one substance for another (mostly the strong one takes the place of the weak)) eccentric shaft oscillation, each The layer screen is easy to install quickly. The service life of the drying roller and the power part is not less than 6000h. The roller can fully use heat, the material curtain flows evenly, and the inclination is required to be adjustable.

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℃.

Road construction machinery is a large range, so let’s talk about one of it, which is the asphalt mixing plant. It is mainly used to produce asphalt, so it is very important among road construction machinery and equipment. An important part, if the quality of the finished product is not good, it will greatly affect the quality of the road. Therefore, below, the editor will use the form of question and answer to guide you to continue learning.

Natural gas is a colorless, odorless, flammable and explosive gas, the main component of which is methane, which accounts for about 98% of natural gas. The density of natural gas is lower than that of air and it is difficult to liquefy. Natural gas is not only a clean green energy for civil, commercial and industrial use, but also a raw gas for chemical industry. The theoretical ignition value of natural gas is 540 degrees, the combustion temperature is 1970 degrees, the calorific value is 40MJ/m3, and the explosion limit is 5%-15%. CNG refers to natural gas that has been compressed to 20-25MP and stored in high-pressure gas tank trucks, and then transported to various gas transmission points to supply gas to residential users, commercial users and industrial users. In order to ensure the normal operation and safety of the asphalt mixing station and our pressure regulating station, our company has specially formulated the following safety protection measures.

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.