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Reasons for the reduction of heating efficiency of asphalt conveying pipes in asphalt mixing plants

When inspecting the asphalt mixing plant, it was found that the asphalt in the pipeline solidified because the temperature of the asphalt transportation pipeline did not meet the requirements. Analysis believes that the reasons for this result are that the high-level oil tank of the heat transfer oil is too low, resulting in poor circulation of the heat transfer oil; the second is that the inner tube of the double-layer pipe is eccentric; the third is that the heat transfer oil pipeline is too long; and the fourth is that the heat transfer oil pipeline is not insulated measure.

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When inspecting the asphalt mixing plant, it was found that the asphalt in the pipeline solidified because the temperature of the asphalt transportation pipeline did not meet the requirements. Analysis believes that the reasons for this result are that the high-level oil tank of the heat transfer oil is too low, resulting in poor circulation of the heat transfer oil; the second is that the inner tube of the double-layer pipe is eccentric; the third is that the heat transfer oil pipeline is too long; and the fourth is that the heat transfer oil pipeline is not insulated measure.
The high-level oil tank of the thermal oil is less than 3m away from the ground, while the high-level heat transfer oil circulation pipe is up to 5m away from the ground. When the asphalt mixing plant is finished working, due to the height difference, all the heat transfer oil in the high circulation pipe returns to the high heat transfer oil tank, and at the same time a large amount of air enters the heat transfer oil circulation pipe.
When the asphalt mixing plant resumes operation, the thermal oil circulation pump cannot completely drain the residual air in the high-altitude thermal oil circulation pipe, resulting in air blockage, which leads to poor circulation of the thermal oil and affects the heating effect. The asphalt conveying pipe of the asphalt mixing station adopts a double-layer pipe structure, that is, the outer pipe is heated by heat-conducting oil and the inner pipe transports asphalt.
After disassembling the asphalt delivery pipe, it was discovered that the inner pipe was not welded to the center of the outer pipe when the double-layer pipe was made, resulting in the inner pipe being eccentric. At the flange where the asphalt delivery pipe is connected, the joint of the heat transfer oil connecting pipe is welded exactly on the side of the eccentric tube with a smaller gap, which results in a reduction in the flow of heat transfer oil at the joint.
The residual welding slag and impurities from the production of asphalt conveying pipes are deposited in the small gaps at the eccentricity, causing a sharp reduction in the flow of thermal oil at the joints, resulting in a reduction in the heating efficiency of the thermal oil in the asphalt conveying pipes. If the heat transfer oil pipeline is too long, the delivery pressure at the end of the heat transfer oil pipeline will be insufficient, and the heat transfer oil at the end of the pipeline will cool down too quickly. When the ambient temperature is low, heat transfer oil pipelines without insulation measures will intensify the heat loss of the heat transfer oil.

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    More Asphalt Processing

    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.

    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 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 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 renovation of the combustion-supporting system of the asphalt mixing plant and the use of DC frequency conversion CNC machining technology are all renovations of the original system. In addition to the above renovation plans, with the existing equipment and personnel, what other measures can be taken in the application to reduce the operating costs of concrete mixing plants?
    At present, China has no mandatory national industry standards for heavy residual oil, and the quality of fuel oil varies greatly. Even from the same dealer, the quality difference between batches is very large, and it contains more residues. Therefore, bridge inspection equipment should be installed on the construction site, and professional personnel should inspect various performance parameters of gasoline and diesel to strictly control quality.
    When the burner is working, if the flame of the combustion aid is red and the smoke from the ash removal chimney is black, this is the manifestation of poor atomization of gasoline and diesel and insufficient combustion aid. At this time, the following measures should be taken to deal with it: properly adjust the distance between the nozzle and the vortex plate, generally push it inward to a suitable distance, the purpose is to prevent the atomized oil cone sprayed from the nozzle from spraying into the vortex plate; effectively adjust the ratio of gasoline and diesel to gas, so that the gasoline and diesel increase the mass conversion law slowly, or the gas increase the mass conversion law quickly; promptly remove the carbon deposits and coke around the nozzle to prevent the flame from deflecting; heavy residual oil contains more residues, which can easily cause serious damage to the high-pressure oil pump and increase the working pressure, affecting the actual effect of atomization and the shape of the flame, so the high-pressure oil pump must be repaired or replaced in time; install metal filter devices in front of the first and second high-pressure oil pumps, and clean them frequently to prevent the residues in the gasoline and diesel from blocking the nozzle.
    The operators should be trained in professional skills on a regular basis to strengthen their job responsibilities and moral education, so that they can establish their respective job responsibilities, understand the importance of their positions, understand the content of their work, and improve their professional level. Skilled operators can properly control the temperature of the asphalt mixing plant mixture to avoid gasoline and diesel waste.
    In order to improve the combustion-supporting effect and effectively reduce the operating costs of asphalt mixing stations, Sinoroader Group kindly reminds that the following issues should be noted when using the burner in the asphalt mixing station: To improve the maintenance of the burner, the burner nozzle should be cleaned of charred materials and carbon deposits on the ignition electrode regularly. The nozzle can be disassembled according to the atomization status; the air-oil ratio of the burner is generally not adjusted, and the fuel pump pressure can be adjusted according to the smoke status and the temperature of the asphalt mixture; the sulfur dioxide generated by the combustion of light fuel oil has a strong corrosion to the bag, so the bag should be maintained regularly and the air pressure changes in the bag should be paid close attention to; water deashing will produce more foam, causing the sand settling tank to flow out, so the sand settling tank should be cleaned in time, and a watering design should be carried out to settle the foam; when the steam pressure decreases or the gear oil pump noise increases, the gear oil pump must be replaced.
    When the burner is started, the fuel oil circulation system should be completed through the valve, and then the burner control box should be opened to start the burner. If the electronic ignition of the fuel oil fails, you can change the inlet tee and use the diesel engine for ignition. After the ignition is successful for 2 minutes, you can convert it into fuel oil. In this way, even the light fuel oil of lower quality can ensure combustion.