JPH0135121B2 - - Google Patents

Description

[Detailed description of the invention] The present invention provides replacement of existing asphalt pavement,
The present invention relates to a dryer for recycling asphalt pavement waste material generated during repair work or construction of equipment buried under existing asphalt pavement.

Asphalt pavement waste material (hereinafter referred to as "waste material") dug up during road construction, etc. can be fully used as asphalt composite material by heating and melting the asphalt. Waste materials are regenerated by heating using a dryer, which is a material heating device.What is important when regenerating waste materials by heating is not to overheat the asphalt contained in the waste materials above the deterioration temperature. In this regard, various efforts have been made to dryers for recycling waste materials. If asphalt is heated above its deterioration temperature, the asphalt components will burn out and its properties will deteriorate, and the components contained in the asphalt will burn and the flue gas from the chimney will turn yellow, and when the water vapor disappears on a clear day, it will become pale blue smoke. This results in the generation of undesirable exhaust smoke from the viewpoint of pollution.

Therefore, conventional dryers for recycling waste materials employ a parallel current heating method in which high-temperature hot air is sent in the same direction as the moving direction of the waste materials to heat the materials. For example, JP-A-54-
No. 100423 uses a cocurrent heating dryer,
New aggregate is supplied from the burner side, and waste material is supplied from the low temperature area near the center of the dryer.

However, in the parallel current heating method, the temperature of the hot air exhausted from the dryer is higher than the temperature of the material after heating. For example, if the material is heated to 160℃, the temperature of the hot air exhausted from the dryer will be around 200 to 250℃. Since the hot air carries away a large amount of heat, heat loss is also large, and the heating efficiency of the dryer becomes poor. If such a co-current heating method is adopted in a dryer that can heat both new aggregate and waste material, priority will be given to heating only the waste material, and dryers that often only heat new aggregate will not be able to use the conventional method. The heating efficiency is lower than that of the flow heating method, making it economically unfavorable.

In view of the above points, the present invention employs a countercurrent heating method that can lower the temperature of the hot air being exhausted, and also improves the heating efficiency of the dryer by creating a structure that prevents waste material from overheating in the dryer's high temperature range. It is something that we are trying to improve.

That is, in the present invention, a burner is disposed at one end of a rotatably tilted drum, and a new aggregate supply section is disposed at the other end. An inner cylinder with perforations is provided,
The gist of this dryer is to provide a dryer for recycling asphalt pavement waste, characterized in that the flame of the burner is formed in an inner cylinder, and a supply section for the asphalt pavement waste is disposed approximately in the middle of the drum.

Hereinafter, the present invention will be explained based on illustrated embodiments. Reference numeral 1 denotes a dryer which is a heating device and is of a rotary kiln type, in which a cylindrical drum 2 having a large number of scraping blades (not shown) arranged around its inner periphery is rotatably supported at an angle. It is rotated at a predetermined speed by a drive device (not shown). Reference numeral 3 denotes an inner cylinder disposed inside the drum 2, and the inner cylinder 3 is provided with a number of perforations 4 on its circumferential surface to improve material heating by heat radiation. It has reached almost the middle part. Reference numeral 5 denotes a burner that forms a flame toward the inner cylinder 3 so that high-temperature hot air passes through the inner cylinder 3. 6 is a belt conveyor for supplying new aggregate into the drum 2, and the new aggregate supplied by the belt conveyor 6 is transferred to the drum 2.
While rolling and flowing down along the drum inclination direction while being scraped up by scraping blades disposed around the inner circumference of the drum, the drum is heated and discharged from the discharge section 7. It is preferable that the scraping blades disposed around the drum 2 have a shape that prevents the scraped material from falling onto the inner cylinder 3 where the inner cylinder 3 is located. Reference numerals 8a, 8b, and 8c are hoppers that store crushed waste materials according to various particle sizes, and feeders 9a, 9b, and 9c, which are equipped with a control device and can freely take out quantitative amounts, store the desired particles according to the documents of the asphalt mixture to be manufactured. An appropriate amount of waste material with a suitable diameter is taken out and supplied to the vicinity of the tip of the inner cylinder 3 at approximately the middle of the drum 2 via the belt conveyor 10 and the screw conveyor 11. The method of supplying waste material to the drum 2 is not limited to the above-described screw conveyor 11. For example, an input chute that communicates with the inside of the drum may be provided approximately in the middle of the drum 2, and the waste material conveyed by the belt conveyor may be fed into the input chute. You may also put it in.

Thus, in the dryer of the present invention, the new aggregate is supplied into the drum 2 by the belt conveyor 6, and while the new aggregate is rolled down in the drum 2 while being scraped up by the scraping blades, the inner cylinder 3 is The hot air from the burner 5, which has formed a flame, is passed through the drum 2 so as to flow countercurrently to the flow of new aggregate, and is heated. In addition, the waste material is supplied via the screw conveyor 11 to the vicinity of the tip of the inner cylinder 3 located approximately in the middle of the drum 2, so that the waste material passing through the high temperature region of the dryer is prevented from directly contacting the high temperature hot air by the inner cylinder 3. The waste material is prevented from being extremely overheated, and is heated by heat radiation from the perforation 4 of the inner cylinder 3 or the surface of the inner cylinder 3. At the same time, the shortage of heat radiation is compensated for by mixing with heated new aggregate. The temperature is then raised to a desired temperature, and the heated mixture of new aggregate and waste material is discharged from the discharge section 7. Even if the fine particles in the waste material are overheated and scattered, the hot air that has passed through the inner cylinder 3 is still at a high temperature, so the fine particles will be burned out and blue smoke, which is a pollution problem, will be emitted from the chimney. There is little risk of it happening.

As described above, the present invention heats waste material and new aggregate by flowing them countercurrently in the dryer, so the temperature of the hot air exhausted from the dryer can be increased to 100%.
Compared to the conventional co-current heating method, which has an exhaust hot air temperature of 200 to 250 degrees Celsius, the exhaust hot air temperature can be lowered considerably, increasing the heating efficiency to 80 to 85 degrees Celsius.
It is possible to improve it up to %. Also,
The inner cylinder 3 is disposed in the high-temperature region of the dryer so that high-temperature hot air passes through the inner cylinder, and the waste material is supplied near the tip of the inner cylinder 3 at approximately the middle of the drum 2. Since the asphalt does not come into direct contact with high-temperature hot air, deterioration of the asphalt component in the waste material due to overheating can be prevented as much as possible.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway schematic front view of an embodiment of the present invention. 1...Dryer, 2...Drum, 3...Inner cylinder,
4... Perforation, 5... Burner, 6... Belt conveyor, 7... Discharge section, 8a, 8b, 8c... Hopper, 9a, 9b, 9c... Feeder, 10...
Belt conveyor, 11... Screw conveyor.

Claims (1)

[Claims] 1. A burner is provided at one end of the rotatably tilted drum, and a new aggregate supply section is provided at the other end. Inside the drum on the burner side, there is an inner cylinder with numerous perforations reaching approximately the middle of the drum. 1. A dryer for recycling asphalt pavement waste material, characterized in that a burner flame is formed in an inner cylinder, and an asphalt pavement waste supply section is arranged approximately in the middle of the drum.