JPS5942762B2 - Asphalt plant pavement waste recycling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recycling asphalt pavement waste in an asphalt plant.

Conventionally, when asphalt pavement waste material (hereinafter referred to as waste material) is recycled in an asphalt plant, it is mixed into a newly produced composite material and carried out by the method shown in Fig. 1.

First, a method for producing a new pavement material will be explained.

Cold aggregate (crushed stone, sand) is heated and dried by an inclined rotary cylindrical heating dryer 1, transported to the upper part of the plant by a hot elevator 2, and sieved by vibrating screen 3 according to particle size.

At this time, it is usually classified into four types and stored in the hot bin 4.

The classified and stored aggregate is weighed by a weighing hopper 5 for each particle size, and is fed into a mixer 6.

At the same time, a predetermined amount of dissolved asphalt (6a) and filler 6b are supplied to the mixer 6 and mixed with the aggregate to form a mixture for asphalt paving.

This mixed material is normally discharged from the mixer 6 at a temperature of 160 to 170°C, so the aggregate fed into the mixer 6 is at a temperature of 170 to 170°C.
The mixture is heated to 180° C., and the mixing time in the mixer 6 is approximately 50 seconds to 1 minute.

When recycling waste materials using the above asphalt plant,
The waste materials excavated from the road are placed in a crusher (
(not shown) etc. to a predetermined particle size.

The crushed waste material is transported by a belt conveyor 7a or the like and stored in a stock bin 7 additionally installed in the asphalt plant.

This stored waste material and new aggregate are weighed by an aggregate measuring hopper 5 and fed into a mixer 6.

At this time, the waste materials input into the mixer 6 are at room temperature, so
In the weighing hopper 5 and mixer 6 of the asphalt plant, heat is absorbed from the high-temperature new aggregate by thermal conduction, and the aggregate is heated and softened.

Even when waste materials are mixed, asphalt 6a and filler 6b in the required ratio to the new aggregate are added to the mixer 6 and mixed to a temperature of 160 to 170° C. to form a composite material.

As described above, in the conventional method for recycling waste materials in an asphalt plant, the waste materials are heated by the heat of new aggregate.

Therefore, compared to the case of producing 100% new aggregate, the heat is absorbed by the waste material, so it is necessary to heat the new aggregate more by that amount.

The waste material is heated while it is in the aggregate weighing hopper 5 and while it is being mixed in the mixer 6, for a total of 1 degree of time.

When adding waste wood as described above, add waste wood at room temperature to 160~
In order to raise the temperature to 170°C, the aggregate must be heated extra, but the upper limit of the heating temperature is about 300°C due to the structure of the aggregate heating dryer and the heat resistance of the device.

Furthermore, depending on the quality of the aggregate, heating it to 300°C may cause internal crystallization water to escape, resulting in a decrease in strength.

Furthermore, when the water content of the waste material is around 3%, it takes time for the water to evaporate in the mixer 6, making it necessary to reduce the mixing ratio of the waste material or extend the mixing time in the mixer 6, resulting in the production of asphalt mixture. Capacity decreases.

As described above, due to restrictions such as the amount of heat that the aggregate can hold and the heat conduction time, it is only possible to increase the mixing ratio of waste materials to about 30%.

As described above, the conventional methods for recycling waste materials in asphalt plants are unsatisfactory from the viewpoint of recycling because the proportion of waste materials that can be added is small, and is not currently being actively adopted.

The present invention has been made in consideration of the above circumstances, and has the function of improving the mixing ratio of waste materials by modifying an existing asphalt plant, and also has the function of producing 100% new mixed material. The present invention provides a method for producing an asphalt pavement mix material, which is equipped with an inclined rotating cylindrical heating dryer for heating and drying aggregates, in which the tilting rotary cylindrical heating dryer for heating and drying the aggregate is tilted. An exhaust slit is provided on the middle circumference of the rotating cylindrical part, and the hot air discharged from the slit is used as a heating heat source for the pavement waste heating dryer.

The present invention will be explained in detail below with reference to the drawings.

FIGS. 2 and 3 show an asphalt plant in which the present invention is implemented, and the reference numeral 11 in the figures indicates an inclined rotating cylindrical heating dryer (hereinafter referred to as an aggregate dryer).

On the higher side of the inclined cylindrical portion 11a of the aggregate dryer 11, there is a part 11e of an aggregate dryer chamber, which is equipped with an input port 11c for cold aggregate transported by a belt conveyor 11b, etc., and an exhaust duct 11d. Provided with an inclined cylindrical part 1
On the lower side of 1a, there is provided a heated aggregate extraction section 11g to which a heating burner 11f is attached.

A plurality of slits 1 are provided in the middle of the inclined rotating cylindrical portion 11a.
1h... is open.

As shown in FIG. 3, the slits 11h... have slits 11h...
A buckle play N1i is attached so as to surround ....

Further, the slits 11h, .
...Manifold 11 that collects hot air to be discharged
j is provided.

A duct N1k for sending the collected hot air is attached to the upper part of this manifold 11j, and this duct 11k is provided with a damper 11m for adjusting the flow rate of the hot air.

In order to make the heated aggregate discharged from the aggregate dryer 11 into a composite material, a hot elevator 12, a vibrating screen 13, a hot bin 1
4, a weighing hopper 15 and a mixer 16 are provided.

In the method of the present invention, an inclined rotating cylindrical heating dryer (hereinafter referred to as a waste material dryer) that heats and dries the waste material is further used.
18 have been newly installed.

A hot air introduction duct 18b connected to the upper duct N1k of the manifold 11j of the aggregate dryer 11 and an input port 18c for inputting crushed waste are attached to the higher side of the waste material dryer tilted rotating cylindrical portion 18a. A chamber portion 18d is provided.

Furthermore, an auxiliary burner 18e is attached to the duct 18b to be used as necessary.

An exhaust duct N8f is provided on the lower side of the inclined rotating cylindrical portion 18a.
and extraction part 18h equipped with heated waste material extraction port 18g.
is provided.

A stock bin 17 is provided to heat and store the waste material at a temperature of about 140° C. extracted through the extraction port 18g, and a feeder 17a is attached to the lower part of the stock bin 17, and the heated waste material in the stock bin 17 is transferred to the weighing hopper 15. It is ready to be inserted.

This stock bin 17 and the outlet 1 of the waste material dryer
A conveyor such as a belt conveyor 17b is disposed between 8g and 8g, which lowers the temperature of the extracted heated waste material and transports it to the stock bin 17.

In addition, dust collectors 11n, 18i and exhaust fans 11o, 1 are installed in the exhaust routes of the aggregate dryer exhaust duct 11d and the waste material dryer exhaust duct 18f, respectively.
8j is provided.

Next, a method for recycling waste materials using this device will be explained.

The cold aggregate is charged into the inclined rotating cylindrical part 11a from the aggregate input port 11c of the aggregate dryer 11, and is then fed into the cylindrical part 11a.
burner 1 while moving downward while being stirred.
170~1 in countercurrent contact with the hot air generated by 1f.
It is heated to about 80°C.

The heated aggregate is discharged from the bottom of the extraction section 11g, transported to the top of the plant by a hot elevator 12, classified into 4 or 5 stages by a vibrating screen 13, and stored separately in hot bins 14. .

The slit 11h provided in the middle part of the cylindrical part 11a of this aggregate dryer 110 allows the hot air to exchange heat with the aggregate.
A portion where the temperature decreases from 0 to 550°C is selected and provided.

Therefore, hot air at 500 to 550° C. is taken out from the slit 11h, collected in the manifold 11j, passed through the upper duct 11k and the hot air introduction duct 18b of the waste material dryer 18, and is supplied to the waste material dryer 18.

The crushed cold waste material is charged into the inclined rotating cylindrical portion 18a from the input port 18c.

This thrown-in waste material comes into contact with the hot air of 500 to 550'C introduced from the duct 18b in parallel flow, and is heated to 140C.

At this time, the waste material input at room temperature had an initial value of 500 to 500
Although it comes into contact with hot air at 50°C, it has been confirmed that asphalt does not deteriorate when the temperature of the hot air is around this level.

Furthermore, since the waste wood and hot air come into contact with each other in parallel flow, the temperature of the hot air decreases as the temperature of the waste wood rises, and it was confirmed that asphalt in the waste wood would not deteriorate if the temperature was set at around 140°C at the 18g outlet of the waste material. .

Further, when the water content of the new aggregate is high and the temperature of the hot air collected in the manifold 11j is low, the preliminary burner of the waste material dryer 18 is ignited to adjust the temperature of the hot air introduced into the waste material dryer 18 to 500 to 550°C. .

Since this hot air discharge duct N8f is provided with an exhaust fan 18j, the waste material dryer 1 is
The amount of hot air introduced at step 8 can be freely selected to accommodate changes in the amount of waste material to be processed.

The waste material heated to about 140° C. by the waste material dryer 18 has properties similar to those of the new composite material.

This heated waste material is stored in the stock bin 17 by means of transportation such as a conveyor 17b.

It is well known that when handling waste materials that have been heated to around 140°C, care must be taken to heat and insulate the equipment used, and it is important to select the type of conveyor, feeder, etc.
A bar feeder, a screw feeder, etc. that can be heated and kept warm may be used, but this is not the gist of the present invention.

The stored heated waste material is dropped into the weighing hopper 15 by the feeder 17a, and is cumulatively weighed together with the new aggregate dropped into the hot bin 14 and the weighing hopper 15, and then put into the mixer 16.

Into this mixer 16, melted asphalt 16a and filler 16b are added and mixed in an amount suitable for the new aggregate,
Asphalt mixture is manufactured.

In this way, the waste material is heated until the temperature difference between it and the heated aggregate becomes about 20° C. before being introduced into the mixer 16, so that the temperature can be uniformized within the mixer 16 in a short time.

Therefore, the ratio of waste wood to new composite material can be increased to about 50% when the moisture content of the waste wood is 3%, and about 70% when the moisture content is 1%.

In addition, when the regeneration process is not required, as long as the damper of the upper duct of the manifold is not closed to discharge hot air, the plant can be operated in exactly the same way as the conventional method as a new composite material production plant.

As described above, the waste material recycling method according to the present invention obtains the thermal energy necessary for heating the asphalt waste material by increasing the combustion of the burner 11f of the aggregate dryer 11. After heating the aggregate by applying high-temperature, large-capacity hot air to the aggregate for a short time, a portion of the hot air whose temperature has been lowered by heating the aggregate is sent to a sulin installed in the middle of the aggregate dryer 11). This method heats the asphalt waste taken out from the 11n, but unlike the case where the asphalt waste is directly heated with high-temperature hot air using a separate burner, the asphalt waste does not deteriorate, and the high temperature of the aggregate does not cause the asphalt waste to deteriorate. Heating with a large volume of hot air is completed in a short time, and thereafter heating is continued with a small amount of hot air that remains in the aggregate dryer 11 without being discharged from Surin Nlh, so it does not affect the aggregate. I never give out.

In addition, when heating asphalt waste using a separate burner, it is necessary to lower the temperature of the combustion gas by the method described above in order to prevent the asphalt waste from deteriorating, and the combustion efficiency will decrease accordingly. However, this is not the case with this invention.

In this invention, the auxiliary burner 18e may also be used, but in this case, a small amount of combustion gas is mixed into the relatively large amount of low-temperature hot air taken out from Surin N1h, so it is possible to prevent the asphalt waste from deteriorating. do not have.

In this way, the present invention accurately captures the physical properties of aggregate and asphalt waste and heats them effectively, so it is possible to dramatically increase the rate of waste mixed into the new composite material.

In addition, since it is possible to produce only new composite materials by simply switching operations, there is no need to install a plant exclusively for recycling and a new composite material production plant, which has many advantages such as energy saving and site savings.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the conventional asphalt mixture production method and recycling method, Fig. 2 is a diagram for explaining the method according to the present invention, and Fig. 3 is a diagram for explaining the method according to the present invention. FIG. 11... Inclined rotating cylindrical heating dryer, (aggregate dryer L11a... Inclined rotating cylindrical part, 11c
...Input port, 11d...Exhaust duct,
11f... Burner, 11h... Exhaust slit, 111... Baffle, 11j...
...Manifold, 11h...Duct, 11
m...Dunbar, 17...Stock bin, 17b...Belt conveyor, 18...
...Tilting rotating cylindrical heating dryer (waste material dryer),
18a... Inclined rotating cylindrical part, 18b...
・Hot air introduction duct, 18c...Inlet, 18e
...Auxiliary burner, 18f...Exhaust duct, 18g...Heating waste material extraction port, 18j...
...Waste dryer exhaust fan.

Claims (1)

[Claims] 1. In an asphalt plant pavement waste recycling method in which asphalt pavement waste is recycled by mixing asphalt pavement waste with dissolved asphalt, filler, etc. into aggregate heat-dried by a tilt-rotating cylindrical heating dryer,
Hot air is discharged from the slit provided on the middle circumference of the inclined rotating cylindrical part of the inclined rotating cylindrical heating dryer and sent to another asphalt pavement waste heating dryer, and the asphalt paving waste heating dryer is used to asphalt pavement. A method for recycling pavement waste materials from an asphalt plant, characterized by heating and drying the waste materials in advance.