The construction of asphalt roads, especially the asphalt pavement of expressways and airports, has a history of high-speed development in China for more than 20 years. According to statistics from the Ministry of Transport, the mileage of expressways in China in 2004 has exceeded 34,200 kilometers, an increase of 4,400 compared to 2003. Kilometers, continuing to remain the second in the world, and the total mileage of highways open to the world exceeds 230,000 kilometers. The asphalt and cement roads in rural areas built in 2003 and 2004 were 192,000 kilometers, a total of 362,000 kilometers. The investment in transportation infrastructure completed in 2004 increased by 21.2% over the previous year, of which the investment in highway construction increased by 19.9% over the previous year. Significant progress was made in highway infrastructure construction. The latest data shows that the current mileage of expressways in the country is 53,000 kilometers, and the highway construction speeds in various provinces are fast. The data is subject to change at any time. It is estimated that by 2010, the total mileage of highways in China will reach 65,000 kilometers.

With the completion and use of expressways, the maintenance workload of expressways is increasing. According to the design life of asphalt pavements of 10-15 years, 10% of the pavements each year are successively entered into the period of repair, reconstruction and expansion. Without mastering the old asphalt recycling technology and recycling equipment, the traditional pavement overhaul process is to mill off the old pavement and use the new asphalt concrete to recapture the new pavement. Milled or broken down a huge number of old asphalt materials, piled up like mountains. With the soaring oil price, the price of petroleum derivative asphalt has also soared like a rocket. Asphalt concrete, these golden treasures, have become unmanageable deposits after highway overhaul, which wastes valuable resources and Seriously pollutes the environment. According to the estimation of domestic authoritative experts, by 2010 China's old asphalt waste will exceed 100 million tons.

Asphalt pavement recycling research was first started in the United States in 1915. By the end of the 1980s, the amount of recycled asphalt mixture in the United States was almost half of the total asphalt mixture in roads. In China, because asphalt pavements were generally thin and the quality of asphalt was poor, in many cases, the surface of asphalt was treated and mixed up and down, the oil and water of asphalt pavement regeneration was not large, and the economic value was not great, and the regeneration was difficult. Therefore, although it has been done in many places before, including the regeneration of residue roads, it has not formed a large climate.

However, the situation has fundamentally changed. As a result of the rapid increase in the mileage of expressways and general highways and the high oil price, asphalt recycling is already economically “profitable”, and the problem of asphalt concrete recycling is imminent. Asphalt regeneration technology can be divided into two types: on-site regeneration and plant-mixed regeneration. On-site regeneration can be divided into on-site cold regeneration and on-site hot regeneration; plant-mixed regeneration can be divided into continuous regeneration equipment and intermittent regeneration equipment. A large number of domestic and foreign application practices have shown that the intermittent thermal regeneration equipment is the best solution to the old asphalt. Its regeneration quality and production cost can meet the practical requirements. The thermal regeneration process and equipment appeared in the late 1970s. At that time, it was hailed as a very effective and revolutionary technology. It has the advantages of fast construction speed and reduced material transportation. Taking the maintenance of two-way four lanes as an example, the paving depth is 10 cm, and about 5,600 tons of asphalt mixture is required per kilometer. At present, the market price of asphalt mixture is 420 yuan / ton, and it is produced according to 50% of the new and old mixture. Excluding other losses, it can save 380,000 yuan per kilometer, and the cost saved is pure profit. Invest in a set of asphalt thermal regeneration equipment. If a 6-10 km highway is overhauled, the investment cost of asphalt thermal regeneration equipment can be recovered.

At present, more than 98% of the asphalt mixing equipment used in China's pavement construction is forced batch mixing equipment. Matching asphalt recycling equipment on the basis of intermittent mixing stations can avoid repeated investment and reduce equipment procurement costs. The AHR series of asphalt recycling equipment produced by Xuzhou Ruima Heavy Industry is specially designed for intermittent mixing equipment and is suitable for intermittent asphalt mixing equipment produced by various manufacturers at home and abroad.

In the process of developing the AHR series of asphalt recycling equipment, Xuzhou Ruima conducted in-depth comparison and analysis of the advantages and disadvantages of various recycling processes. According to the problems that easily occur in the regeneration of asphalt materials, the following scheme was determined to be the most practical scheme. This solution is designed to solve the technical defects encountered in the processing of recycled asphalt concrete using ordinary intermittent asphalt concrete mixing equipment:

① When the recycled material is heated, it is burned and burned with flame directly;

② Secondary heating sieving cannot be performed after heating the recycled material, resulting in uncontrollable grading;

③ Recycled material is blocked during transportation and metering when it is heated and bonded;

④The problem of secondary pollution of asphalt fumes during heating.

 figure 1

Process flow of intermittent asphalt concrete regeneration equipment

The technical solution adopted by the AHR series of hot asphalt regeneration equipment is a method for treating the recycled materials of the intermittent asphalt concrete mixing equipment. On the basis of the existing intermittent mixing equipment, the heating, regeneration agent adding and metering devices of the old asphalt recycling materials are added. (It may not be used according to the actual situation), make full use of the function of the existing intermittent asphalt concrete mixing equipment. Various functions in the dashed box of FIG. 1 are performed by the existing stirring equipment. The treatment method is characterized in that the reclaimed material after screening and pretreatment uses the existing belt scale batching system to perform the primary distribution control of the reclaimed material and then reheat; the temperature-adjustable air medium is used to prevent the regenerated material from scorching and aging; The waste heat of the drum heats and maintains the hot material hoist; uses electric heaters or heat-conducting oil to heat and store the storage hopper and the measuring hopper to solve the sticking and blocking of the material path; uses special air heating device to re-burn the asphalt smoke in the exhaust gas, Both pollution and waste heat can be used.

 Working principle of intermittent asphalt concrete recycling equipment

According to the above-mentioned intermittent production process flow and the technical problems to be solved, the following design of a regeneration device scheme matching the existing intermittent asphalt concrete mixing equipment is shown in Figure 2: (Due to the different types of recycled asphalt Need to use different modifiers, resulting in the use of the same modifier function can not achieve the desired effect; and through experiments to confirm that when the old mixture is added less than 40%, the performance of recycled materials without regenerant can still In line with the requirements of highway pavement materials, the solution does not use regenerative addition and metering devices)

Recycled stream:

① The recycled materials after crushing and cold screening are loaded into different batching bins, and the primary batching control of the recycled materials is controlled by the belt batching scale.

② Recycled material after primary preparation is realized, and it is sent to the drying drum by the oblique belt of the aggregate, which is heated by the hot air heating medium in the drying drum.

③ The heated reclaimed material is fed into the reclaimed material warehouse by the hot material hoist through the smoke box.

④ The material door switch of the recycled material warehouse is controlled by the secondary metering bucket scale. After the bucket scale is measured, it directly enters the mixing pot of the matching batch type asphalt concrete mixing equipment, and is mixed with the new material in the mixing pot.

Heating air flow:

① Fresh air enters the burner to burn oil, and is further burned in the combustion chamber and mixed with the circulating exhaust gas. Finish heating air and burning light oil in exhaust gas.

② The heated air medium enters the drying drum, where it is mixed with the recycled material to heat the recycled material.

③The exhaust gas after heating the recycled material enters the smoke box, where one part is returned to the combustion chamber through the exhaust gas circulation circuit; the other part enters the aggregate drying cylinder of the supporting mixing equipment through the hot material elevator and the exhaust pipe, and the waste material is used to heat the hot material. Hoist.

④ The smoke box is equipped with a sensor that detects the air pressure to control the circulating air volume of the exhaust gas and the timing and opening of the valve that is discharged into the pipe of the aggregate drying cylinder.

The recycled asphalt mixture produced by the AHR series of asphalt recycling equipment has been tested by authoritative institutions' laboratories, and various physical and chemical indicators such as gradation ratio, Marshall stability, penetration, high and low temperature stability have reached the national standard specifications. Blue smoke emission indicators European emission standards. The measurement accuracy meets the requirements of national standards. The proportion of hot recycled used materials can be adjusted arbitrarily, and the used materials can be up to 50%. It is a domestic first-class advanced equipment.

At present, most pavement construction units in China use hot recycled asphalt mixtures for the bottom and middle layers. However, for old asphalt pavements with recyclable value, the highest economic benefit is the use of hot reclaimed asphalt mixtures for paving. LRZ series of asphalt recycling equipment can design new grading ratio according to the aging degree and gradation of old recycled materials, and accurately control the addition ratio of new and old materials, so that the mixed recycled asphalt mixture is tested by authoritative agencies and all indicators are completely Meet construction requirements.

With a special internal structure, it can make full use of thermal energy to prevent the adhesion of hot recycled materials to the cylinder wall and the feeding blades. It is equipped with an imported infrared temperature measuring device to control the temperature within ± 5 ° C. The specially designed burner adopts radiant heat transfer heating method, which can effectively prevent the aging and burning of asphalt, and ensure the performance of hot recycled asphalt mixture.

Because of the forced batch mixing equipment, compared with continuous mixing equipment, it has its unique advantages in terms of precise measurement control, adjustment of mixing time and temperature control. The recycled mixture containing modified asphalt is regenerated. Utilization has a higher advantage.

During the heating and drying process of old asphalt mixture, a large amount of blue smoke and exhaust gas will be generated. If these gases are directly discharged into the air, they will seriously pollute the environment. Xuzhou Ruima Heavy Industry uses the blue smoke and exhaust gas to enter the drying drum of the host of the asphalt mixing equipment through the flue, and performs secondary combustion to completely eliminate harmful exhaust gas, eliminate pollution, and benefit the country and the people.

At present, more than 98% of the asphalt mixing equipment currently under construction and use in China are forced intermittent. In response to the domestic market demand, the AHR series of asphalt regeneration equipment is electrically controlled. Because it adopts the industrial bus standard technology, only the interface device is needed. It can easily be perfectly combined with the control system of any equipment at home and abroad. It is an ideal choice for the construction unit of asphalt mixing equipment, and it will definitely bring you rich profits and returns.

 

 

 

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