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Analysis on improving the production efficiency of asphalt mixing plant

At present, the production efficiency of asphalt mixing plants in my country’s asphalt construction is far lower than the theoretical efficiency at the time of design. The low efficiency of organic waste gas treatment will not only delay the construction process and cause a waste of resources, but also the quality of the construction will not be very good. guarantee. In the construction of asphalt pavement, the main reasons for the low production efficiency of the asphalt plant are insufficient supply of mixture, resulting in loss of continuity of construction, improper equipment parameter settings, excessive overflow and other problems. Effective measures must be taken to deal with these problems, and ultimately improve production efficiency and ensure construction quality.

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At present, the production efficiency of asphalt mixing plants in my country’s asphalt construction is far lower than the theoretical efficiency at the time of design. The low efficiency of organic waste gas treatment will not only delay the construction process and cause a waste of resources, but also the quality of the construction will not be very good. guarantee. In the construction of asphalt pavement, the main reasons for the low production efficiency of the asphalt plant are insufficient supply of mixture, resulting in loss of continuity of construction, improper equipment parameter settings, excessive overflow and other problems. Effective measures must be taken to deal with these problems, and ultimately improve production efficiency and ensure construction quality.

1. Analysis of factors affecting construction quality
1.1 Low equipment production efficiency There are five main factors that cause low equipment production efficiency and unstable output:
First, the mix ratio of asphalt and concrete is inappropriate. The mix ratio of the asphalt mixture is used throughout the entire construction, and the scientific guidance of the mix ratio and production mix ratio must be fully utilized. Once the mix ratio is unreasonable, it will be extremely easy to affect the quality of construction, and ultimately affect the service life of the pavement when it is put into use. It will also increase the project cost accordingly for the construction company, which is not conducive to the company’s cost control and economic benefits. This requires that the mixing plant should try to prevent material overflow and material waiting during use, so as to improve production efficiency and thereby reduce costs.
Second, the selection of sand and stone is unreasonable. There are corresponding grading ranges for the specifications and models of sand and stone. However, due to insufficient strictness during procurement and verification, some gradings seriously exceeded the range, resulting in a large amount of material waste. This phenomenon not only results in low production efficiency and insufficient output, but also wastes resources and increases the cost of the enterprise.
Third, the water content of sand and gravel exceeds the standard. The drying barrel of the asphalt mixing plant and its production capacity and model are matched with each other. Once the moisture content of materials such as sand and gravel exceeds a certain standard, the drying capacity will be reduced accordingly. As a result, the amount of sand and gravel at the set temperature is greatly reduced per unit time, and the output is subsequently reduced.
Fourth, the combustion efficiency of gas burners is low. The temperature of the corresponding stone cannot be kept stable due to low combustion efficiency. Therefore, the heating capacity of the drying barrel is reduced, and the discharge speed is slowed down, which ultimately affects the production efficiency.
Fifth, the equipment operating parameters are improperly set. In terms of parameter setting issues, the main problems are improper setting of the time for dry and wet mixing, and improper adjustment of the opening and closing time of the bucket door. Under normal circumstances, each mixing production cycle is 45-60S. Only under this setting can the final production capacity reach the expected value. Taking the 2000 type asphalt plant as an example, when the mixing time is forty-five seconds, the theoretical output per hour should reach 160t/h; the actual mixing time is fifty-five seconds, and the actual output per hour But it’s only 130t/h. It can be seen that if you want to increase the output, you should minimize the mixing cycle time while ensuring that the quality meets the requirements.
1.2 The temperature of the discharge material is unstable. The temperature requirements in the production process of asphalt concrete are very strict. If the temperature is too high or too low, it will affect the quality of the asphalt. If the temperature is too high, the asphalt will be easily scorched. The asphalt produced under such conditions is called paste and is a waste material without any use value. If the temperature is too low, it will easily affect the adhesion. The adhesion of asphalt and sand and gravel materials will not be strong and uneven, and they cannot be used. Both of the above situations will cause a lot of losses and waste, with the average cost per ton being around 400. In order to reduce the waste of materials and increase costs, this requires strict temperature control during the production process, careful observation and measurement, to ensure that the quality of the materials is up to standard.
1.3 The oil-stone ratio is unstable. The oil-stone ratio mainly refers to the mass ratio of fillers such as asphalt and sand in asphalt concrete. It is an important indicator to maintain the quality of asphalt concrete. There are two main reasons for the unstable oil-stone ratio: the content of soil, dust, etc. in the sand and gravel materials exceeds the standard. Since the content of soil, dust, etc. seriously exceeds the standard, it cannot be completely removed even after dust removal treatment. Therefore, when the gravel is mixed with asphalt, it is difficult to form when there is too little asphalt adhered to the surface and the asphalt is rolled. Second, the metering system fails. During production, the zero points of the asphalt weighing scale and mineral powder weighing scale systems drift, which leads to measurement errors. Especially once an error occurs in the asphalt measuring scale, it will have a greater impact on the oil-stone ratio. This requires frequent calibration of the measurement system during production to ensure measurement accuracy.

2 Common fault analysis
2.1 Failure of the cold material feeding device If the variable speed belt conveyor stops, there may be two reasons. One is a motor failure, and the other is that the belt is stuck due to foreign matter and cannot continue to run. If it is a motor problem, you should first check the motor’s control inverter during inspection to see if the circuit status is normal or if there is a circuit break. It is also possible that the belt is not tight enough. If it is confirmed to be a foreign matter problem, it needs to be cleaned as soon as possible.
2.2 Mixer failure When using the mixer, the fault can be identified by the sound. If the sound is abnormal, it may be due to the overload operation of the mixer, which in turn causes the fixed support to be dislocated. Or the fixed bearing is damaged. When encountering the above situations, it is necessary to reset, fix or replace the bearing with a new one. Especially the mixer’s arms, blades, and internal guards. When these important parts are found to be seriously damaged or even fallen off, they need to be replaced directly. If the temperature of the discharging material is abnormal, the temperature sensor needs to be checked.
2.3 Burner failure It is extremely easy for burner problems to occur during the operation of the mixing station. When heating is required, the burner cannot ignite normally. When encountering this situation, first check the inside of the operating room to see if all the conditions supporting ignition are met, such as the status of the induced draft fan, blower, etc., whether the position is correct, and whether the switch is turned on, etc. If all the conditions for normal ignition have been met, but the burner still does not operate normally, the next step needs to be checked. Check whether the initial ignition has been carried out, whether there is enough fuel and whether the passage is clear. Check the ignition motor of the burner, mainly checking the high-voltage package, electrodes and other issues. If all the above are normal, the fuel pump needs to be checked.
2.4 Abnormal negative pressure Negative pressure mainly refers to the atmospheric pressure in the drying drum. The positive pressure inside the drum mainly comes from the blower, while the negative pressure mainly comes from the induced draft fan. If the negative pressure is too large, it will cause too much cold air inside the drum to take away heat energy, and the amount of material will be greatly increased, so the negative pressure must be strictly controlled.

3 Measures to Improve Production Efficiency
3.1 Maintenance of Mixing Plant To improve the production efficiency of asphalt mixing station, we must first improve the maintenance of the mixing station to ensure the normal operation of the mixing station and maximize the output and quality. The asphalt mixing plant is one of the equipment that is prone to failure during construction. Daily equipment maintenance should be paid attention to to improve equipment utilization and production efficiency.
The first is the maintenance of the tank. During the operation of the mixing plant, the tank is seriously worn. During daily maintenance, if it is found that the tank liner, blade stirring arm, and material door seal are worn, if the wear is minor, timely adjustment is required, and if the wear is serious, it needs to be replaced directly. It must be cleaned promptly after each use to prevent concrete from solidifying and affecting normal operation. All parts of the tank must be inspected regularly to ensure that all aspects are normal and safe before operation can begin.
Secondly, the maintenance and adjustment of the winch motor. The braking torque of the mixer is controlled and adjusted by the large nut on the back seat of the motor, so pay special attention to the use of the nut when using it, and operate according to the corresponding procedures according to the actual situation. Then, maintenance of the loading rack and bracket. Pay attention to the maintenance of the contact parts between the loading rack and the roller. Grease should be applied frequently inside and outside the groove. Firstly, it can reduce the resistance during operation and ensure the normal speed of feeding. Secondly, proper lubrication can effectively reduce wear. Thereby reducing costs. If the bracket is found to be deformed, timely processing must be carried out to avoid safety accidents. Maintenance of travel limiter. The limiters of the mixing station are divided into limit limits, upper and lower limits, etc. In daily maintenance, timely inspection must be paid attention to, including the sensitivity and reliability of the switch, as well as problems such as circuits and components.
3.2 Improve the overall quality of operators To improve the production efficiency of asphalt mixing plants, in addition to ensuring the normal operation of the asphalt plants, it is also necessary to improve the overall quality of operators to reduce the impact of human factors on production efficiency. Operators need regular training to improve their professionalism and practical experience. At the same time, they must undergo strict assessments before taking up the job, and only start operations after meeting the requirements. At the same time, ideological education and safety training of personnel are carried out to improve the safety awareness and sense of responsibility of construction personnel, so that problems can be discovered and solved in a timely manner.

4 Conclusion
In summary, there are two main factors that cause low production efficiency of asphalt mixing plants, namely human factors and equipment factors. In response to these two aspects of the problem, it is necessary to continuously improve the comprehensive quality of the staff to ensure the correctness and effectiveness of the operation; attention should be paid to daily maintenance of the equipment, and frequent inspections should be carried out during use to ensure the safety and effectiveness of the work. Quality of construction. Only by starting from the above two aspects can we ultimately improve production efficiency.

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    More Asphalt Processing

    The drive unit is one of the important components of the asphalt mixing plant, so whether it can be reliably operated must be highly valued to avoid adverse effects on the entire asphalt mixing plant. In order to ensure that the drive unit in the asphalt mixing plant is indeed complete and reliable, the following maintenance measures are essential.
    The first thing to pay attention to is the universal rotating part of the drive unit of the asphalt mixing plant. This part has always been a fault-prone part. In order to reduce the occurrence of faults, grease should be added on time, and the wear should be checked frequently, and repaired and replaced in time. Users should also prepare the universal shaft assembly to avoid affecting the working process of the entire asphalt mixer.
    Secondly, the cleanliness of the hydraulic oil used in the asphalt mixing plant must be ensured. After all, the working environment of the equipment is relatively harsh, so it is necessary to prevent sewage and mud from entering the hydraulic system. The hydraulic oil should also be replaced regularly according to the requirements of the manual. Once water or mud is found mixed in the hydraulic oil during inspection, the hydraulic system should be stopped immediately to clean the hydraulic system and replace the hydraulic oil.
    Since there is a hydraulic system, of course, a matching cooling device is also required, which is also an important focus in the drive system of the asphalt mixing plant. To ensure that its function can be fully exerted, on the one hand, the hydraulic oil radiator should be cleaned regularly to prevent the radiator from being blocked by cement; on the other hand, the radiator electric fan should be checked to see if it is running normally to prevent the hydraulic oil temperature from exceeding the standard.
    In general, as long as the hydraulic oil of the asphalt mixing plant drive device is kept clean, there are generally few faults; but the service life varies from manufacturer to manufacturer, so pay attention to its alkalinity observation and replace it in real time.

    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 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.

    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.

    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.