JPH0259883B2 - - Google Patents

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention is directed to heating of asphalt pavement waste, in which recycled composite material produced by crushing asphalt pavement waste is heated in a recycling dryer to regenerate it as an asphalt mixture. Regarding playback methods.

``Conventional technology'' Traditionally, a co-current rotary cylindrical dryer has often been used as a recycling dryer for asphalt pavement waste, but this recycling dryer has been used to produce recycled materials by crushing asphalt pavement waste. When drying and heating aggregates, it is necessary to prevent thermal deterioration of the asphalt contained in the recycled aggregates as much as possible. This is because when the above-mentioned asphalt deteriorates due to heat, the quality of the recycled asphalt mixture deteriorates, and the combustion products of asphalt get mixed into the exhaust gas discharged from the dryer.
This is because it may cause pollution problems. Therefore, conventionally, recycling dryers 1 and 2 as shown in FIG. 7 or 8 have been used.

That is, the recycle dryer 1 shown in FIG.
A burner 7 is attached to the combustion chamber 6 via the combustion chamber 6, and
An exhaust manifold 10 is provided with a first material input port 8 and an outlet 9 for the asphalt mixture m at the other end 5b, and a second material inlet is provided at the intermediate portion between the one end 5a and the other end 5b. An input port 11 is provided. Materials n that are not likely to cause thermal deterioration of the asphalt, such as new aggregates or recycled aggregates with large particle sizes, are input from the first material input port 8 and are heated to a high temperature on the upstream side of the combustion gas g from the burner 7. (800
The fine-grained recycled aggregate r, whose asphalt tends to undergo thermal deterioration, is heated by the combustion gas g at a temperature of 100°C to 900°C. It is heated by the combustion gas g whose temperature has been lowered.

In addition, the recycling dryer 2 shown in Figure 8
In the recycling dryer 1, the material input port is connected to the material input port 12 at one end 5a of the rotating drum 5.
In addition, an air mixture chamber 13 is interposed between the rotating drum 5 and the combustion chamber 6. and,
The combustion gas g from the burner 7 is mixed with outside air a (or a part of the exhaust gas e) in the air mixture chamber 13 to generate hot air, which is guided into the rotating drum 5 to reduce the temperature of the hot air inside the material input port 12. The temperature is kept at about 600°C, thereby preventing thermal deterioration of the asphalt in the recycled aggregate r input from the material input port 12.

In FIGS. 7 and 8, the reference numeral 14 denotes a material supply device consisting of a belt conveyor, 15 a conveyance device for the asphalt mixture m, 1
6 is a pedestal.

``The problem that the invention seeks to solve'' However, the recycling dryer 1 in Figure 7
In this method, material n such as new aggregate and fine recycled aggregate r are respectively charged from two material input ports 8 and 11, and therefore has the following drawbacks.

(b) The structure of the device becomes complicated, which increases equipment costs.

(b) Operation becomes complicated, making it difficult to stabilize product quality.

(c) To prevent thermal deterioration of asphalt, it is usually necessary to add about 20% of the total weight of new aggregate.
Raw material costs will increase.

On the other hand, in the recycle dryer 2 shown in FIG. 8, when the same thermal energy as in the above-mentioned recycle dryer 1 is applied to the rotating drum 5, the amount of combustion gas g becomes large, which causes the following problem. .

(a) The heat loss of the exhaust gas e increases, the overall thermal efficiency decreases, and the amount of fuel consumed in the burner 7 increases.

(b) When the production capacity is the same, the diameter of the rotating drum 5 is larger than that of the recycling dryer 1, and the exhaust fan, duct, and dust collector of the exhaust gas e discharge system are also larger. For this reason,
Equipment costs and power costs are high.

The present invention was made in view of the above circumstances, and
A heating method for asphalt pavement waste that can reliably prevent thermal deterioration of the asphalt content in recycled aggregate and obtain a high-quality asphalt mixture, while also keeping equipment costs, operating costs, and raw material costs low. The purpose is to provide a reproduction method.

"Means for Solving the Problem" In order to achieve the above object, the first invention provides a method for introducing recycled aggregate into a rotating drum from one end thereof and moving it toward the other end. In the method for heating and regenerating asphalt pavement waste material, the asphalt pavement waste is heated by combustion gas fed into the inside of the drum from one end to the other end and regenerated as an asphalt mixture, when the recycled aggregate is put into the inside of the rotating drum A gas is blown into the input position to send the fine particles in the recycled aggregate to a position downstream of the combustion gas than the coarse particles, and the second invention is the first invention. In implementing the
The third invention is characterized in that the temperature around the fine particles of the recycled aggregate is lowered than the temperature of the whole inside of the rotating drum by controlling the amount of gas blown and/or the temperature. When feeding the recycled aggregate into the rotating drum, after sieving the recycled aggregate into fine particles and coarse particles, gas is blown into the fine particle input position to separate the fine particles into coarse particles. The combustion gas is sent to a position on the downstream side of the combustion gas.

"Operation" In the first invention, only the fine particles of the recycled aggregate, which are prone to thermal deterioration of the asphalt content, are blown into the downstream region of the combustion gas by the gas pumping force by utilizing the weight difference, The second invention prevents thermal deterioration of the asphalt by heating it with downstream combustion gas having a low temperature.Furthermore, the second invention heats the asphalt with the downstream combustion gas, which has a low temperature. In addition to sending the fine particles to the downstream side, the temperature around the fine particles is kept low to further suppress heat exchange. Furthermore, the third invention sieves the recycled aggregate into fine particles and coarse particles before blowing the gas onto the recycled aggregate, and the fine particles are smoothed more smoothly on the downstream side of the combustion gas by the pumping force of the gas. It was designed to be transferred to

"Example" Examples of the present invention will be described below.

1 to 3 show a recycling dryer 20 suitable for carrying out the first and second methods of the present invention, which are different from the conventional recycling dryers 1 and 2 shown in FIGS. 7 and 8. Parts having the same basic structure are given the same reference numerals and their explanations will be omitted.

In the figure, reference numeral 21 denotes a blower manifold that rotatably accommodates one end 5a of the rotating drum 5, and the blower manifold 21 has a material inputting chute 22 that guides the recycled aggregate r supplied from the material supply device 14 into the rotating drum 5. installed. This material inputting chute 22 has a hopper-shaped receiving portion 22a at its upper end that protrudes upward from the upper part of the ventilation manifold 21.
It is comprised of a cylindrical body that is inclined downwardly toward the rotating drum 5, and the lower part 22c from the middle part to the lower end 22b is inserted inside one end 5a of the rotating drum 5, and bottom edge 2
2b is bent and narrowed toward the inner center of the rotary drum 5 in the left-right direction of the rotary drum 5 (vertical direction in FIG. 3). A jacket-shaped surrounding member 23 is attached to the outside of the lower part 22c of the material inputting chute 22, and covers the lower part 22c from below with an interval. The surface is the bottom edge 2 above.
2b, and the bottom surface of the lower end 23a is bent in a substantially horizontal state.

Furthermore, a blower 24 operated by a drive motor 24a is installed outside the rotary drum 5, and a suction port of the blower 24 is connected to a circulation pipe branched from an exhaust duct 25 connected to the exhaust manifold 10. The ends of the duct 26 are connected. A first damper 28 whose opening degree is adjusted by a control motor 27 is provided at a predetermined position of this circulation duct 26, and a predetermined position downstream of this first damper 28 is provided with an air vent. An outside air introduction duct 29 is connected to the outside air introduction duct 29, and a second air introduction duct whose opening degree is adjusted by a control motor 30 is also connected to the outside air introduction duct 29.
A damper 31 is provided. Further, a gas blowing duct 32 guided into the air blowing manifold 21 is connected to the discharge port of the blower 24, and a terminal end of the gas blowing duct 32 is connected to the back surface of the surrounding member 23. Then, a gas A such as exhaust gas e, outside air a, or a mixture thereof discharged from the exhaust manifold 10
is guided into the interior of the surrounding member 23 by the blower 24, and is blown out around the lower end 22b of the material inputting chute 22 (i.e., the fall path of the recycled aggregate r, and the range of approximately the same width as this fall path). It's becoming like that.

Furthermore, a temperature sensor 33 is disposed in the ventilation manifold 21, with its detection end positioned below the lower end 22b of the material input chute 22. The temperature sensor 33, each control motor 27, 30 of the first and second dampers 28, 31, and the drive motor 24a of the blower 24 are connected to a control device 34, and a detection signal from the temperature sensor 33 is connected to the control device 34. The first and second dampers 28, 31 and the blower 24 are controlled based on this.

In addition, 35 in the figure is a burner blower.

In the recycle dryer 20, the recycled aggregate r sent by the material supply device 14 is charged into the rotating drum 5 from one end 5a through the material input chute 22. While moving from one end 5a of the rotating drum 5 to the other end 5b, the asphalt mixture is dried and heated by the combustion gas g from the burner 7 and regenerated as an asphalt mixture m, which is taken out from the outlet 9 of the exhaust manifold 10 and transported. conveyed by device 15. In addition, the above-mentioned combustion gas g is sent from one end 5a of the rotating drum 5 to the other end 5b to dry and heat the recycled aggregate r.
is introduced into the exhaust gas e from the exhaust manifold 10 to the exhaust duct 25, and is discharged into the atmosphere through a dust collector (not shown) and the like.

In the first invention, in the above process, when the recycled aggregate r is introduced into the rotating drum 5, gas A is blown into the input position of the recycled aggregate r.
The fine particles inside are sent to a position downstream of the combustion gas g than the coarse particles. That is, when charging recycled aggregate r, the blower 24 is operated to blow gas A such as exhaust gas e, outside air a, or a mixture thereof through the gas blowing duct 32 onto the outer surface of the surrounding member 23 and the material input chute 22. The gas is introduced into the formed gas passage and blown out from below the lower end 22b of the material input chute 22 toward the other end 5b of the rotating drum 5. Then, when the recycled aggregate r that has slid down inside the material input chute 22 falls into the rotating drum 5 from its lower end 22b, this gas A is blown onto the recycled aggregate r. Then, the heavy coarse particles in the recycled aggregate r fall downward and move toward the other end 5b of the rotating drum 5 while being heated by the high-temperature combustion gas g, but the lighter particles in the recycled aggregate r The fine particles are suspended in the airflow generated by the gas A and are transported to the rotating drum 5.
It is carried to the other end 5b side and is dried and heated by the relatively low temperature combustion gas g downstream. Therefore, the fine particles of the recycled aggregate r, which are easily subject to thermal deterioration due to the asphalt content, are dried and heated by the low-temperature combustion gas g, thereby preventing their thermal deterioration, and the coarse particles, which are less likely to undergo thermal deterioration, are The minutes are from one end 5a of the rotating drum 5 to the other end 5
While moving towards b, it is sufficiently dried and heated,
Thereby, the quality of the recycled asphalt mixture m is maintained at a good level.

Furthermore, when using the recycling dryer 2 as shown in FIG. Since the moving speed is low and the residence time is long, there is a high possibility of thermal deterioration, but in the above method, in addition to the fine particles being transported to the low temperature side, the residence time is shortened, and While there is an air current around the fine particles, there is a synergistic effect such that the temperature of the surrounding area is lower than the temperature of the whole inside of the rotating drum 5, and the possibility of thermal deterioration is further reduced. Furthermore, in the above method, the finer the particle size of the recycled aggregate r is, the more it is blown to the downstream side of the combustion gas g, so the shorter the time required for drying and heating, the shorter the residence time, and the whole of the recycled aggregate r. It has the advantage that it is uniformly dried and heated.
Further, in the recycling dryer 20, the lower end 23a of the surrounding member 23 and the material input chute 22
The lower end 22b is bent in a required direction, and the gas A guided into the gas passage formed by the surrounding member 23 and the material inputting chute 22 hits the recycled aggregate r that has fallen from the material inputting chute 22. Since it is sprayed in a predetermined range of the path, the fine particles of the recycled aggregate r are reliably blown to the downstream side of the combustion gas g with a small amount of gas A.

Therefore, overheating of the recycled aggregate r is prevented and the generation of blue smoke is suppressed, and the temperature for each particle size is uniform, and recycling is performed with good thermal efficiency.

Here, the particle size of the recycled aggregate r is normally distributed in the range of 0 to 30 mm, and the particle size and distance of the fine particles blown away change depending on the flow rate of the gas A to be blown. Therefore, by adjusting the flow rate of gas A, the recycled aggregate r with a predetermined particle size is blown a predetermined distance. Specifically, the flow rate of gas A is adjusted so that recycled aggregate r with a particle size of about 3 mm r floats 15
A speed of about m/sec is effective.

In addition, the amount of gas A to be blown can achieve the purpose with the amount of excess air conventionally introduced from the burner 7 side, that is, 0.3 to 0.5 times the amount of combustion air. In comparison, the amount of heat required is small, and there is little decrease in thermal efficiency.

Next, in carrying out the first invention, the second invention controls the blowing amount and/or temperature of the gas A to adjust the temperature around the fine particles of the recycled aggregate r within the rotating drum. It is characterized by being lower than the overall temperature. That is, recycled aggregate r
The temperature at the input position is detected by the temperature sensor 33, and this temperature is the set temperature (450°
A range of ~600℃ has practical effects. ), the temperature of the gas A is controlled by adjusting the amount of mixed exhaust gas e through the first damper 28, and by adjusting the amount of outside air a sucked through the second damper 31. Alternatively, the entire amount of gas A blown may be controlled by controlling the rotation speed of the drive motor 24a.
As a result, the temperature around the fine particles blown away by the gas A is sufficiently lowered than the temperature of the entire interior of the rotating drum 5, and thermal deterioration of the asphalt particles is more effectively prevented.

In addition, the degree of thermal deterioration of the asphalt content increases as the asphalt content increases and the particle size of the recycled aggregate r becomes finer, so the temperature around the fine particles should be optimized depending on the particle size distribution and properties of the recycled aggregate r. adjust. At this time, for example, in the case of recycled aggregate r with a low asphalt content or recycled aggregate r with a low fine particle content, in order to keep the temperature around the fine particles relatively high, the amount of gas A should be reduced or the exhaust gas e should be mixed. However, reducing the amount of gas A means reducing the total gas amount, which reduces energy loss and increases thermal efficiency.In addition, increasing the mixing ratio of exhaust gas e improves waste heat recovery. It will be advantageous.

Although the recycle dryer 20 is equipped with a dedicated blower 24 for blowing the gas A, a burner blower 35 may be used instead.In that case, the burner blower 35 may have a larger capacity. put. Further, the method of feeding the recycled aggregate r into the rotating drum 5 may be a method using a screw feeder 36 as shown in FIG. 4, or a method using a belt conveyor 37 as shown in FIG. , a rotary bucket, etc. may also be used.

Next, FIG. 6 shows an example of a recycling dryer for carrying out the method of the third invention, and 40 in the figure is a material input chute. This material inputting chute 40 is supported by the blower manifold 21 via a spring 41 (or an elastic body such as rubber), and is vibrated by a vibrator 42 such as a swing motor. Inside thereof, a sieve 43 is attached to a wire mesh, a grizzly grid, a punched iron plate, or the like. Then, recycled aggregate r with a certain particle size (usually 5 to 7 mm) is sieved to 4
3 and flow down along the bottom plate 40a, and large particles flow down over the sieve 43 and fall into the rotating drum 5.

In the third invention, after sieving the recycled aggregate r into fine particles and coarse particles, gas A is introduced into the position where the fine particles are introduced.
The fine particles are sent to a position downstream of the combustion gas g than the coarse particles. That is, in the recycle dryer shown in FIG. 6, when the vibrator 42 is operated to vibrate the material input chute 40 and the recycled aggregate r is input into the material input chute 40, the recycled aggregate r is Sieve 43
The particles are divided into coarse particles and fine particles, and the fine particles flow down along the bottom plate 40a. Then, when the gas A is blown onto the falling portion of the fine particles, the fine particles are effectively blown away by the downstream region of the combustion gas g without being blocked by the coarse particles.

Here, it is even more preferable to not only sift the recycled aggregate r vertically, but also to sift it horizontally by changing the shape of the material inputting chute 40. Further, the material inputting chute 40 may be a rotating chute to have a trommen (rotary sieving) function.

``Effects of the Invention'' As explained above, the first invention blows gas into the input position when recycled aggregate is introduced into the rotating drum, thereby removing recycled aggregate that is prone to thermal deterioration due to the asphalt content. Since the fine particles are blown away by this gas and then dried and heated by the downstream low-temperature combustion gas, thermal deterioration of the asphalt components can be reliably prevented and a high quality asphalt mixture can be obtained. Since there is no need to add new aggregate and only one material input system is required, equipment costs and raw material costs can be kept low, and the amount of combustion gas can be reduced, so fuel costs, power costs, etc. can also be reduced. In addition, the second invention controls the amount of gas blown into the drum so that the temperature around the fine particles of the recycled aggregate blown away by the gas is lower than the temperature of the entire inside of the rotating drum. Thermal deterioration of the asphalt content can be more reliably prevented.Further, the third invention sieves the recycled aggregate into fine particles and coarse particles, and then sieves the fine particles with gas under the combustion gas. Since the particles are sent into the basin, fine particles are transported extremely smoothly, and thermal deterioration can be more reliably prevented.

Through the first to third inventions, it is possible to prevent overheating of recycled aggregates having different particle sizes, suppress generation of blue smoke, and perform recycling with uniform temperature for each particle size and high thermal efficiency.

[Brief explanation of drawings]

Figures 1 to 3 show an example of a recycling dryer for carrying out the first and second inventions, with Figure 1 being an overall side view and Figure 2 being an enlarged view of the circular portion in Figure 1. , FIG. 3 is a sectional view taken in the direction of the - arrow in FIG. 2, FIGS. 4 and 5 are side views showing other examples of the above-mentioned recycling dryer, and FIG. 6 is a diagram for carrying out the third invention. FIG. 7 and FIG. 8 are side views showing an example of a conventional recycling dryer. 5... Rotating drum, 5a... One end, 20... Recycle dryer, 22... Material input chute, 23... Surrounding member, 24... Blower.

Claims (1)

[Claims] 1. Recycled aggregate obtained by crushing asphalt pavement waste is introduced into the interior of a rotating drum from one end and moved toward the other end. In a method for heating and regenerating asphalt pavement waste material in which the asphalt pavement waste is heated by combustion gas sent toward the end and regenerated as an asphalt mixture, when the recycled aggregate is introduced, gas is introduced into a predetermined range of the fall path of the recycled aggregate. A method for heating and regenerating asphalt pavement waste material, characterized in that the fine particles in the recycled aggregate are sent to a position downstream of the combustion gas than the coarse particles by blowing the gas onto the recycled aggregate. . 2. The method for heating and regenerating asphalt pavement waste material according to claim 1, wherein the gas is outside air, exhaust gas discharged from a rotating drum, or a mixed gas of outside air and the exhaust gas. 3 Recycled aggregate obtained by crushing asphalt pavement waste was introduced into a rotating drum from one end, moved toward the other end, and fed into the rotating drum from one end toward the other end. In a method for heating and regenerating asphalt pavement waste, which is heated with combustion gas and regenerated as an asphalt mixture, when the recycled aggregate is introduced, gas is blown into a predetermined range of the falling path of the recycled aggregate to remove the gas. By blowing the gas onto the recycled aggregate, the fine particles of the recycled aggregate are sent to a position downstream of the combustion gas compared to the coarse particles, and at the same time, the amount and/or temperature of the gas blown is controlled. A method for heating and regenerating asphalt pavement waste material, characterized in that the temperature around fine particles of recycled aggregate is lowered than the temperature of the entire inside of a rotating drum. 4. The method for heating and regenerating asphalt pavement waste material according to claim 3, wherein the gas is outside air, exhaust gas discharged from a rotating drum, or a mixed gas of outside air and the exhaust gas. 5 Recycled aggregate obtained by crushing asphalt pavement waste was introduced into a rotating drum from one end, moved toward the other end, and fed into the rotating drum from one end toward the other end. In a method for heating and regenerating asphalt pavement waste in which the recycled aggregate is heated with combustion gas and recycled as an asphalt mixture, when the recycled aggregate is introduced into the rotating drum, the recycled aggregate is divided into fine particles and coarse particles. A method of heating and regenerating asphalt pavement waste material, which is characterized by blowing gas into a predetermined range of the falling path of the fine particles and sending the fine particles to a position downstream of the combustion gas than the coarse particles. Method. 6. The method for heating and regenerating asphalt pavement waste material according to claim 5, wherein the gas is outside air, exhaust gas discharged from a rotating drum, or a mixed gas of outside air and the exhaust gas.