Large-scale asphalt mixture mixing equipment is a key equipment for the construction of asphalt pavement projects. The installation and debugging of the mixing equipment directly affect its operating status, pavement construction progress and quality. Based on work practice, this article describes the technical points of installation and debugging of large-scale asphalt mixture mixing equipment.

Selection for the type of the asphalt plant

Adaptability
The equipment model should be selected based on a comprehensive study based on the company's qualifications, the scale of the contracted project, the task volume of this project (tender section), combined with factors such as the climate of the construction area, effective construction days, company development prospects, and company economic strength. The equipment production capacity should be greater than the construction task volume. 20% larger.

Scalability
The selected equipment should have the technical level to adapt to the current construction requirements and be scalable. For example, the number of cold and hot silos should be six to meet the control of the mix ratio; the mixing cylinder should have an interface for adding additives to meet the requirements for adding fiber materials, anti-rutting agents and other additives.

Environmental protection
When purchasing equipment, you should fully understand the environmental protection indicators of the equipment to be purchased. It should comply with environmental regulations and the requirements of the environmental protection department in the area where it is used. In the procurement contract, the environmental protection emission requirements of the thermal oil boiler and the dust collector device of the drying system should be clearly defined. The operating noise of the equipment should comply with the regulations on noise at the enterprise boundary. Asphalt storage tanks and heavy oil storage tanks should be equipped with various overflow flue gases. collection and processing facilities.

Install for the asphalt plant
Installation work is the basis for determining the quality of equipment use. It should be highly valued, carefully organized, and implemented by experienced engineers.
Preparation
The main preparation work includes the following six items: First, entrust a qualified architectural design unit to design basic construction drawings based on the floor plan provided by the manufacturer; second, apply for distribution and transformation equipment according to the requirements of the equipment instruction manual, and calculate the distribution capacity. The power requirements for ancillary equipment such as emulsified asphalt and modified asphalt should be taken into consideration, and 10% to 15% of the surplus passenger capacity should be left; secondly, transformers of appropriate capacity must be installed for domestic power consumption at the site to ensure the stable operation of production equipment Fourth, the high and low voltage cables in the site should be designed to be buried, and the distance between the transformer and the main control room should be 50m. Fifth, since the power installation procedures take about 3 months, they should be processed as soon as possible after the equipment is ordered to ensure debugging. Sixth, boilers, pressure vessels, measuring equipment, etc. must go through relevant approval and inspection procedures in a timely manner.

Installation process
Foundation construction The foundation construction process is as follows: review drawings → stake out → excavation → foundation compaction → steel bar binding → installation of embedded parts → formwork → silicon pouring → maintenance.
The foundation of the mixing building is generally designed as a raft foundation. The foundation must be flat and dense. If there is loose soil, it must be replaced and filled. It is strictly prohibited to use the pit wall for direct pouring of the underground foundation part, and formwork must be installed. If the average day and night temperature is lower than 5°C for five consecutive days during construction, insulation measures must be taken according to winter construction requirements (such as foam boards in the formwork, building sheds for heating and insulation, etc.). The installation of embedded parts is a key process. The plane position and elevation must be accurate, and the fixing must be firm to ensure that the embedded parts do not move or deform during pouring and vibration.
After the foundation construction is completed and acceptance conditions are met, foundation acceptance must be carried out. During acceptance, a rebound meter is used to measure the strength of the concrete, a total station is used to measure the plane position of the embedded parts, and a level is used to measure the foundation elevation. After passing the acceptance, the hoisting process begins.
Hoisting construction The hoisting construction process is as follows: mixing building → hot material lifting equipment → powder silo → powder lifting equipment → drying drum → dust collector → belt conveyor → cold material silo → asphalt tank → thermal oil furnace → main control room → appendix.
If the legs of the finished product warehouse on the first floor of the mixing building are designed with embedded bolts, the strength of the concrete poured in the second time must reach 70% before the hoisting of the above floors can continue. The lower stair guardrail must be installed in time and firmly installed before it can be hoisted upward layer by layer. For parts that cannot be installed on the guardrail, a hydraulic lift truck should be used, and safety facilities should be equipped to ensure safety protection. When selecting a crane, its lifting quality should meet the requirements. Full communication and disclosure must be made with the hoisting driver before hoisting operations. Hoisting operations are prohibited in strong winds, precipitation and other weather conditions. At the appropriate time for hoisting construction, arrangements should be made to lay equipment cables and install lightning protection equipment.
Process Inspection During the operation of the mixing equipment, periodic static self-inspections should be carried out, mainly to conduct a comprehensive inspection of the structural components of the mixing equipment to ensure that the installation is firm, the verticality is qualified, the protective railings are intact, the liquid level of the thermal oil high-level tank is normal, and the power and The signal cable is connected correctly.

debug for the asphalt plant

Idle debugging
The idling debugging process is as follows: test-run the motor → adjust the phase sequence → run without load → measure the current and speed → observe the operating parameters of the distribution and transformation equipment → observe the signals returned by each sensor → observe whether the control is sensitive and effective → observe the vibration and noise. If there are any abnormalities during idling debugging, they should be eliminated.
During idling debugging, you should also check the sealing condition of the compressed air pipeline, check whether the pressure value and movement of each cylinder are normal, and check whether the position signals of each moving part are normal. After idling for 2 hours, check whether the temperature of each bearing and reducer is normal, and calibrate each load cell. After the above debugging is normal, you can purchase fuel and start debugging the thermal oil boiler.

Thermal oil boiler commissioning
Dehydration of thermal oil is a key task. The thermal oil must be dehydrated at 105°C until the pressure is stable, and then heated to an operating temperature of 160 to 180°C. The oil must be replenished at any time and exhausted repeatedly to achieve stable inlet and outlet pressures and stable liquid levels. . When the temperature of the insulated pipes of each asphalt tank reaches the normal operating temperature, raw materials such as asphalt, gravel, ore powder can be purchased and prepared for commissioning.

Feeding and debugging
The debugging of the burner is the key to feeding and debugging. Taking heavy oil burners as an example, qualified heavy oil should be purchased according to its instructions. The method to quickly detect heavy oil on site is to add diesel. High-quality heavy oil can be dissolved in diesel. The heating temperature of heavy oil is 65~75℃. If the temperature is too high, gas will be produced and cause fire failure. If the parameters of the burner are set correctly, smooth ignition can be achieved, the combustion flame will be stable, and the temperature will increase with the opening, and the cold material system can be started for feeding.
Do not add stone chips with a particle size less than 3mm during the first test run, because if the flame suddenly goes out, the undried stone chips will adhere to the drum guide plate and the small mesh vibrating screen, affecting future use. After feeding, observe the aggregate temperature and hot silo temperature displayed on the computer, discharge the hot aggregate from each hot silo separately, pick it up with a loader, measure the temperature and compare it with the displayed temperature. In practice, there are differences in these temperature values, which should be carefully summarized, measured repeatedly, and differentiated to accumulate data for future production. When measuring temperature, use an infrared thermometer and a mercury thermometer for comparison and calibration.
Send the hot aggregate from each silo to the laboratory for screening to check whether it meets the corresponding range of the sieve holes. If there is mixing or silo mixing, the reasons should be identified and eliminated. The current of each part, reducer and bearing temperature should be observed and recorded. In the waiting state, observe and adjust the position of the two thrust wheels of the flat belt, the inclined belt, and the roller. Observe that the roller should run without impact or abnormal noise. Analyze the above inspection and observation data to confirm whether the drying and dust removal system is normal, whether the current and temperature of each part are normal, whether each cylinder operates normally, and whether the time parameters set by the control system are applicable.
In addition, during the feeding and debugging process, the positions of the switches of the hot material bin door, aggregate scale door, mixing cylinder door, finished product bin cover, finished product bin door, and trolley door should be correct and the movements should be smooth.

trial production
After the material input and debugging work is completed, you can communicate with the construction technicians to conduct trial production and pave the test section of the road. Trial production must be carried out according to the mixture ratio provided by the laboratory. Trial production must be transferred to the batching and mixing state only after the measured temperature of the hot aggregate reaches the requirements. Taking AH-70 asphalt limestone mixture as an example, the aggregate temperature should reach 170~185℃, and the asphalt heating temperature should be 155~165℃.
Arrange a special person (tester) to observe the appearance of the asphalt mixture at a safe position on the side of the transport vehicle. The asphalt should be evenly coated, without white particles, obvious segregation or agglomeration. The actual measured temperature should be 145~165℃, and the Good appearance, temperature recording. Take samples for extraction tests to check the gradation and oil-stone ratio to check the control of the equipment.
Attention should be paid to test errors, and a comprehensive evaluation should be carried out in conjunction with the actual effect after paving and rolling. A trial production cannot draw a conclusion on the control of the equipment. When the cumulative output of the mixture of the same specification reaches 2000t or 5000t, the computer statistical data, actual quantity of consumed materials, quantity of finished products and test data should be analyzed together. get conclusion. The asphalt measurement accuracy of large asphalt mixing equipment should reach ±0.25%. If it cannot reach this range, the reasons should be found and solved.
Trial production is a stage of repeated debugging, summary and improvement, with a heavy workload and high technical requirements. It requires close cooperation from various departments and requires management and technical personnel with certain experience. The author believes that trial production can be considered completed only after debugging all parts of the equipment to operate stably and reliably, all parameters to be normal, and the quality of the mixture to be stable and controllable.

Staffing
Large-scale asphalt mixture mixing equipment should be equipped with 1 manager with engineering machinery management and work experience, 2 operators with high school education or above, and 3 electricians and mechanics. According to our practical experience, the division of work types should not be too detailed, but should be specialized in multiple functions. Operators should also participate in maintenance and can replace each other during work. It is necessary to select personnel who can endure hardships and love to delve into management and operations to improve the overall ability and work efficiency of the entire team.

acceptance
The managers of large-scale asphalt mixture mixing equipment should organize manufacturers and construction technicians to summarize the debugging process. The sewage treatment equipment should test and evaluate the trial production mixture quality, equipment control performance, and safety protection facilities, and compare them with the requirements of the procurement contract and instructions. , form written acceptance information.
Installation and debugging are the basis for safe and efficient operation of equipment. Equipment managers should have clear ideas, focus on innovation, make overall arrangements, and strictly abide by safety technical regulations and schedules to ensure that equipment is put into production as scheduled and operates smoothly, providing a strong guarantee for road construction.