JP2007031938A - Asphalt plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an asphalt plant for improving mileage by effectively using waste heat of a drier. <P>SOLUTION: This asphalt plant 1 comprises the drier 2 heating and drying an aggregate G, a cyclone 3 being a dust collector collecting dust generated in the drier 2, a bag filter 4 removing the dust included in exhaust gas, a fuel supply facility 6 supplying heavy oil J to the drier 2, and a heat exchanger 5 exchanging heat between the exhaust gas and the heavy oil J. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an asphalt plant, and more particularly to an asphalt plant that improves fuel efficiency by effectively using waste heat from a dryer.

  An asphalt plant is a plant which manufactures asphalt compound materials mainly by mixing aggregate, stone powder, and asphalt with a predetermined composition. In a conventional asphalt plant, high-temperature exhaust gas from a dryer that heats and drys aggregates is generally discharged from a chimney through a cyclone (dust collector) and a bag filter by an exhaust fan.

Moreover, in the asphalt plant described in Patent Document 1, exhaust gas from a dryer is guided to a deodorization furnace to burn odor components. At this time, the exhaust gas from the dryer burns in contact with hot air of about 700 to 800 ° C. in a deodorizing furnace, and most of the odorous components made of hydrocarbons are decomposed into water and carbon dioxide. And the hot air discharged | emitted from a deodorizing furnace heats the exhaust gas from the dryer supplied to a deodorizing furnace and the primary air supplied to the burner of a deodorizing furnace via two heat exchangers, Then, it discharges | emits from a chimney. Is done.
JP-A-8-209616 (paragraph 0017, FIG. 1)

By the way, a general asphalt plant often uses one kind of heavy oil (A heavy oil) that can be used without heating as a fuel for a dryer or a deodorizing furnace. The kinematic viscosity of Class 1 heavy oil is defined as 20 mm ² / s or less at 50 ° C. in the JIS standard (K2205-1980).

However, since the viscosity of heavy oil greatly depends on the temperature, for example, the viscosity of heavy oil increases as the temperature decreases. Then, it becomes difficult to supply heavy oil to the asphalt plant, and the fuel consumption of the asphalt plant decreases. Moreover, when the viscosity of heavy oil becomes high, when heavy oil is injected in a mist state and burned, heavy oil is not sprayed properly, combustion efficiency is reduced, and fuel efficiency is deteriorated.
On the other hand, in order to avoid such a situation, if an asphalt plant is additionally provided with a heater or the like for warming heavy oil, the running cost for that increases, and the fuel efficiency also deteriorates.

  This invention is made | formed in view of this problem, and makes it a subject to provide the asphalt plant which improved the fuel consumption by utilizing effectively the waste heat of a dryer.

  The present invention is an asphalt plant for producing an asphalt mixture, a dryer for heating an aggregate, a fuel supply facility for supplying heavy oil to a device using heavy oil as fuel among the devices of the asphalt plant, And a heat exchanger for exchanging heat between the exhaust gas from the dryer and the heavy oil.

  According to such a configuration, the heavy oil supplied to the fuel oil fueled device (hereinafter sometimes abbreviated as “heavy oil fuel device”) among the devices of the asphalt plant by the heat exchanger and the exhaust gas from the dryer. Since heat exchange is performed between the fuel oil and the fuel oil, the temperature of the heavy oil increases and the viscosity of the heavy oil decreases. Therefore, heavy oil can be efficiently supplied to the heavy oil fuel device. Moreover, since the viscosity of heavy oil is falling, spraying of heavy oil is performed appropriately. Therefore, the combustion efficiency of heavy oil is improved. Therefore, the fuel consumption of the asphalt plant can be improved.

  Here, among the devices of the asphalt plant, as the device using heavy oil as fuel, for example, (1) a dryer for heating and drying aggregates, and (2) deodorizing by burning odor components contained in exhaust gas A deodorizing furnace, (3) a hot oil heater that heats a medium (mainly oil) for warming stored asphalt, and the like.

  Moreover, it is preferable that the exhaust gas from a dryer is supplied to a heat exchanger, after the temperature falls to 70-90 degreeC.

If the temperature of the exhaust gas is within this range, the fuel consumption of the asphalt plant can be improved safely and effectively. That is, if the temperature of the exhaust gas is supplied to the heat exchanger in a state of 90 ° C. or higher, the temperature of the heavy oil becomes too high and the risk of ignition increases. On the other hand, when the temperature of the exhaust gas is 70 ° C. or lower, the temperature of the heavy oil is too low, the viscosity increases, and the fuel efficiency improvement effect is diminished.
In the JIS standard (K2205-1980), the flash point of Class 1 and Type 2 heavy oil is set to 60 ° C. or higher, and the flash point of Class 3 heavy oil is set to 70 ° C. or higher.

  The exhaust gas from the dryer is preferably supplied to the heat exchanger after passing through the bag filter.

According to such a configuration, the exhaust gas from which dust has been removed by the bag filter is supplied to the heat exchanger. Therefore, dust does not accumulate on the heat exchanger, and maintenance is easy. Further, since the dust is reduced, the piping in the heat exchanger is hardly worn and the durability of the heat exchanger is improved.
Further, the exhaust gas after passing through the bag filter often decreases to about 70 to 90 ° C. In other words, it is preferable to adjust the length and equipment from the dryer to the bag filter so that the temperature of the exhaust gas after passing through the bag filter is about 70 to 90 ° C. According to this structure, the fuel consumption of an asphalt plant can be improved safely and effectively by using the exhaust gas that has passed through the bag filter.
According to the inventors' research, in an asphalt plant having a cyclone type dust collector between the dryer and the bag filter, the temperature of the exhaust gas exhausted from the dryer is about 140 ° C., and the temperature of the exhaust gas exhausted from the cyclone. It was found that the temperature of the exhaust gas exhausted from the bag filter is about 70 to 90 ° C. when the temperature is about 110 ° C.

  The heat exchanger also has an exhaust gas pipe through which exhaust gas flows, and one end of the exhaust gas pipe is connected to the exhaust side of the bag filter, and the other end of the exhaust gas pipe is connected to the air supply side of the bag filter. It is preferable.

  According to this configuration, the exhaust gas passed through the heat exchanger can be circulated through the bag filter. Therefore, dust contained in the exhaust gas can be more reliably removed while effectively using the waste heat of the exhaust gas.

  In addition, the heat exchanger includes a heavy oil pipe through which heavy oil flows and a straight exhaust pipe that is disposed inside the heavy oil pipe and through which exhaust gas from the dryer flows. Is good.

  According to this configuration, since the exhaust gas pipe is disposed inside the heavy oil pipe, the heat exchanger can be configured in a double pipe structure. Therefore, heat exchange can be achieved between heavy oil and exhaust gas by bringing heavy oil into contact with the outer peripheral surface of the exhaust gas pipe. In addition, since the exhaust gas pipe is configured in a linear shape, friction (collision) between the exhaust gas pipe and the dust can be reduced as much as possible even when the exhaust gas contains dust. For this reason, the exhaust gas piping is not easily worn, and the durability of the heat exchanger is improved.

Here, as for the exhaust gas piping, it is sufficient that at least a portion disposed inside the heavy oil piping is configured in a linear shape. The parts arranged inside the heavy oil piping are difficult to maintain such as inspection and replacement. Therefore, it is preferable to configure them so that they do not wear easily, but other parts are inspected or replaced. Is relatively easy, for example, the pipe may be bent toward the bag filter.
Furthermore, if the exhaust gas piping of the heat exchanger having such a configuration is connected to the bag filter, the amount of dust is reduced, and it becomes more difficult to wear. Therefore, the durability of the heat exchanger is further improved, and maintenance is further facilitated.

  Moreover, it is preferable that the heat sink is formed in the outer peripheral surface of exhaust gas piping.

According to this configuration, since the heat radiating plate is formed on the outer peripheral surface of the exhaust gas pipe, the contact area with the heavy oil is increased, and the heat exchange efficiency between the exhaust gas and the heavy oil can be improved. In addition, a plurality of heat radiation plates may be provided at a predetermined interval, or may be provided so as to be continuous in a spiral shape. When the heat radiating plate is spiral, the contact area between the heavy oil and the heat radiating plate can be increased while improving the flow of heavy oil, so that the heat exchange efficiency can be improved.
In addition, it is preferable that the heavy oil pipe is configured in a structure with good heat retention and the exhaust gas pipe is configured in a structure with good heat dissipation. For example, by covering the heavy oil piping with a material having high heat retention such as urethane, a structure with good heat retention can be obtained. Further, for example, by configuring the exhaust gas pipe with a metal having high thermal conductivity, a structure with good heat dissipation can be obtained.

  According to the present invention, the fuel consumption of the asphalt plant is improved by effectively using the waste heat from the dryer by providing a heat exchanger that performs heat exchange between the heavy oil as fuel and the exhaust gas of the dryer. There is a remarkable effect.

<First Embodiment>
A first embodiment for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description is omitted.

<Configuration of asphalt plant>
FIG. 1 is a schematic configuration diagram illustrating an asphalt plant according to the first embodiment.
As shown in FIG. 1, the asphalt plant 1 includes a dryer 2 that heats and dries the aggregate G, a cyclone 3 that is a dust collector that collects dust generated in the dryer 2, and a bug filter 4 that removes dust contained in the exhaust gas. And a fuel supply facility 6 that supplies heavy oil J as fuel to the dryer 2 and a heat exchanger 5 that performs heat exchange between the exhaust gas and heavy oil J.

  The asphalt plant 1 includes a cold elevator CE that supplies the aggregate G to the dryer 2, a hot elevator HE that transports the aggregate G heated and dried by the dryer 2, and the heat-dried bone, in addition to the above-described devices. Hot bin HB for storing material G, measuring instrument K for measuring aggregate G, mill mixer M for mixing and stirring aggregate G, stone powder F and asphalt A, hot silo HS for storing manufactured asphalt mixture AG, bug An exhaust fan Fn that exhausts exhaust gas from the filter 4, a chimney C that exhausts exhaust gas, and the like are provided.

  The dryer 2 is a device that heats and dries the aggregate G. As shown in FIG. 1, the dryer 2 mainly includes a drum 21 into which the aggregate G is charged and a burner that heats the aggregate G loaded into the drum 21. 22.

The drum 21 is configured to be rotatable so as to stir the charged aggregate G. At this time, the dust attached to the aggregate G is dried by the stirring by the drum 21 and the heat of the burner 22 to generate dust. A cold elevator CE for charging the aggregate G is installed on one end side of the drum 21. Further, a discharge port (not shown) for discharging the heated aggregate G is provided on the other end side of the drum 21. The aggregate G discharged from the discharge port is transported to the hot bin HB by the hot elevator HE.
Further, an exhaust port 21 a for discharging high-temperature exhaust gas together with dust is provided on one end side of the drum 21.

  The burner 22 is a device that burns the heavy oil J to obtain a high temperature, and is installed on the other end side of the drum 21. A pipe 64 for supplying heavy oil J from the fuel supply facility 6 is connected to the burner 22.

The cyclone 3 is a dust collector that separates and collects dust contained in the exhaust gas by using centrifugal force, and is connected to an exhaust port 21a of the dryer 2 through a pipe 11, as shown in FIG. The cyclone 3 is connected to the bag filter 4 via the pipe 12. That is, the exhaust gas from which the dust has been removed is exhausted to the bag filter 4 through the pipe 12. Note that dust collected by the cyclone 3 is limited to relatively large dust, and fine dust is sent to the bag filter 4 together with the exhaust gas.
The temperature of the exhaust gas when supplied to the cyclone 3 is about 140 ° C.

The bag filter 4 is a device that removes dust by passing exhaust gas through a filter (not shown). As shown in FIG. 1, the cyclone 3 is connected to one end side (supply side) of the bag filter 4 via a pipe 12 so that exhaust gas is supplied. Further, an exhaust fan Fn is connected to the other end side (exhaust side) of the bag filter 4 via a pipe 13 so that the exhaust gas in the bag filter 4 can be exhausted to the chimney C. A filter (not shown) is installed inside the bag filter 4.
The temperature of the exhaust gas when supplied to the bag filter 4 is about 110 ° C., and the temperature of the exhaust gas when exhausted from the bag filter 4 is about 70 to 90 ° C.

  The heat exchanger 5 is a device that exchanges heat between the exhaust gas and the heavy oil J through the partition wall, and passes the exhaust gas that has passed through the bag filter 4 and the heavy oil J that is sent to the burner 22 as shown in FIG. It can be made to. The heat exchanger 5 will be described in detail later with reference to FIG.

  The fuel supply facility 6 is a facility for supplying heavy oil J as fuel to the burner 22 of the dryer 2. As shown in FIG. 1, the fuel supply facility 6 mainly includes a heavy oil tank 61 that stores the heavy oil J, and the heavy oil J to the dryer 2. It comprises a pump 62 for feeding oil and pipes 63 and 64. A heat exchanger 5 is interposed between the pipe 63 and the pipe 64 so that the heavy oil J can be heated using waste heat of the exhaust gas.

FIG. 2: is sectional drawing which showed the heat exchanger which concerns on 1st Embodiment, (a) is AA sectional drawing of (b), (b) is BB sectional drawing of (a). .
As shown in FIG. 2, the heat exchanger 5 according to the first embodiment includes a heavy oil pipe 51 through which heavy oil J flows and an exhaust gas pipe 52 through which exhaust gas that has passed through the bag filter 4 flows. This is a so-called double pipe heat exchanger configured in a double pipe structure.

  As shown in FIGS. 2A and 2B, the heavy oil pipe 51 has a circular cross section, and has an inlet 51a on one end side and an outlet 51b on the other end side. The inflow port 51 a is connected to the fuel supply facility 6 through a pipe 63. Further, the outlet 51 b is connected to the burner 22 of the dryer 2 through a pipe 64. As a result, the heavy oil J can flow through the heavy oil pipe 51.

  As shown in FIGS. 2A and 2B, the exhaust gas pipe 52 is a straight pipe having a circular cross section having a smaller diameter than the heavy oil pipe 51, and penetrates the heavy oil pipe 51 to the inside thereof. Has been placed. As shown in FIG. 2B, the exhaust gas pipe 52 has an air supply port 52a on one end side and an exhaust port 52b on the other end side. The air supply port 52 a is connected to the exhaust side of the bag filter 4 through the pipe 13 and the pipe 14. The exhaust port 52 b is connected to the air supply side of the bag filter 4 via the pipe 12 and the pipe 15. Thereby, the exhaust gas exhausted from the bag filter 4 can be circulated to the bag filter 4 through the exhaust gas pipe 52.

  Note that a check valve (not shown) is installed in the pipe 14 to prevent the backflow of exhaust gas. In addition, an ejector (not shown) is installed at a connection portion between the pipe 15 and the pipe 12 so that the exhaust gas in the exhaust gas pipe 52 can be sucked.

  Here, since the exhaust gas flowing through the exhaust gas pipe 52 passes through the bag filter 4 and the dust is removed, the dust does not collide with the exhaust gas pipe 52 and is not easily worn. ing. In addition, at least a portion of the exhaust gas pipe 52 disposed inside the heavy oil pipe 51 is formed in a linear shape as shown in FIG. Therefore, even if a small amount of dust is contained in the exhaust gas that has passed through the bag filter 4, the exhaust gas piping 52 and the dust are unlikely to collide. Therefore, the durability of the heat exchanger 5 is improved and the maintenance work can be omitted.

  In addition, as shown in FIGS. 2A and 2B, the exhaust gas pipe 52 includes a plurality of heat dissipation plates 53 on the outer peripheral surface thereof. The heat radiating plate 53 is a circular plate formed with a smaller diameter than the inner diameter of the heavy oil pipe 51, and is arranged at predetermined intervals along the axial direction of the exhaust gas pipe 52. A gap S is provided between the outer peripheral end of the heat radiating plate 53 and the inner peripheral surface of the heavy oil pipe 51 so that the heavy oil J can flow therethrough. The heavy oil J flows while contacting the surface of the heat radiating plate 53 and the outer peripheral surface of the exhaust gas pipe 52, so that heat can be efficiently exchanged with the exhaust gas.

  Note that the heat exchanger 5 is preferably disposed close to the bag filter 4, and more preferably configured integrally with the bag filter 4. If it does in this way, the installation space of the heat exchanger 5 can be saved.

<Operation of asphalt plant>
Next, the operation of the asphalt plant 1 will be described with reference to FIGS.

  When the operation of the asphalt plant 1 is started, the aggregate G is supplied from the cold elevator CE into the drum 21 of the dryer 2. The aggregate G put into the drum 21 is heated and dried by the heat of the burner 22.

  The heat-dried aggregate G is sent to the hot bottle HB by the hot elevator HE, weighed by the measuring device K, and put into the mill mixer M. The aggregate G is mixed with the stone powder F and the asphalt A in the mill mixer M to become the asphalt mixture AG. The asphalt mixture AG is sent to the hot silo HS.

  On the other hand, the exhaust gas from the dryer 2 heated by the burner 22 is sent to the cyclone 3 through the pipe 11. The cyclone 3 removes dust contained in the exhaust gas using centrifugal force. The exhaust gas from which the dust has been removed is sent to the bag filter 4 via the pipe 12.

  In the bag filter 4, minute dust remaining in the exhaust gas is removed by passing the exhaust gas through the filter. The exhaust gas from which the dust has been removed is exhausted from the chimney C by the exhaust fan Fn connected to the exhaust side of the bag filter 4 via the pipe 13. At this time, a part of the exhaust gas is sent to the heat exchanger 5 through the pipe 14 branched from the pipe 13.

  When the exhaust gas is sent to the heat exchanger 5, the exhaust gas pipe 52 and the heat radiating plate 53 are warmed by the heat of the exhaust gas. A heavy oil pipe 51 is arranged outside the exhaust gas pipe 52, and the heavy oil J flowing through the heavy oil pipe 51 receives heat from the surfaces of the exhaust gas pipe 52 and the radiator plate 53. .

  The heated heavy oil J has a reduced viscosity, and the resistance when flowing through the pipe 64 is reduced. Therefore, since the output of the pump 62 can be reduced, the fuel consumption of the asphalt plant 1 can be improved. Moreover, since the viscosity of heavy oil is falling, heavy oil spraying is performed appropriately in the burner 22. Therefore, the combustion efficiency of heavy oil is improved. As a result, a high amount of heat can be obtained with a small amount of fuel, and the fuel consumption of the asphalt plant 1 can be improved. Moreover, since the said effect can be achieved by simple structure, the initial cost of the asphalt plant 1 does not increase.

Second Embodiment
Subsequently, the asphalt plant according to the second embodiment will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description is omitted.

FIG. 3 is a schematic configuration diagram illustrating an asphalt plant according to the second embodiment. In FIG. 1, a part of the asphalt plant is omitted.
The asphalt plant 10 according to the second embodiment is different from the asphalt plant 1 according to the first embodiment in that the structure of the heat exchanger 5 ′ and the deodorizing furnace 7 are provided.

As shown in FIG. 3, the heat exchanger 5 ′ according to the second embodiment includes a heavy oil tank 61 that is a part of the fuel supply facility 6, and a helical exhaust gas pipe disposed inside the heavy oil tank 61. 52 '.
According to such a configuration, the heat of the exhaust gas is transferred to the heavy oil J through the surface of the spiral exhaust gas pipe 52 ′, and the temperature of the heavy oil J increases. Therefore, the viscosity of heavy oil J falls and the fuel consumption of asphalt plant 10 improves.

The deodorizing furnace 7 is a device for deodorizing by burning odor components contained in the exhaust gas, and is installed between the exhaust fan Fn and the chimney C as shown in FIG.
The deodorizing furnace 7 includes a burner (not shown) using heavy oil J as a fuel, and the temperature in the deodorizing furnace 7 can be increased to about 700 to 800 ° C. Further, the deodorizing furnace 7 is connected to a pump 62 via a pipe 65 so that the heavy oil J can be supplied from the fuel supply facility 6.

  As a result, the exhaust gas from the dryer 2 (see FIG. 1) comes into contact with hot air of about 700 to 800 ° C. in the deodorizing furnace 7 and burns, and most of the odor components made of hydrocarbons are decomposed into water and carbon dioxide. . At this time, since the viscosity of the heavy oil J is lowered, when the heavy oil J is sprayed in a mist and burned, the heavy oil is properly sprayed, and the combustion efficiency is improved. Therefore, the fuel consumption of the asphalt plant 10 is improved.

  The best mode for carrying out the present invention has been described in detail with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and may be appropriately changed without departing from the gist of the present invention. Is possible.

  For example, in the first embodiment, a plurality of disk-shaped heat sinks are arranged at equal intervals, but the present invention is not limited to this, and the heat sink is formed in a spiral shape (screw shape) to facilitate the flow of heavy oil. May be. Moreover, you may make it easy to flow heavy oil by notching a part of disk to zigzag. If it does in this way, the distance through which heavy oil flows in a heat exchanger becomes long, and heat exchange can be performed effectively.

  In the first and second embodiments, the exhaust gas that has passed through the bag filter 4 is allowed to flow through the heat exchangers 5 and 5 ′. However, the present invention is not limited to this, and the exhaust gas from the dryer 2 is used. Thus, any configuration that warms heavy oil can be used. At this time, it is preferable to pass through the heat exchanger after adjusting the temperature of the exhaust gas so that the heavy oil does not ignite.

  As an exhaust gas temperature adjustment facility (adjustment method), although not shown, a thermometer is installed at the exhaust port 52b of the exhaust gas pipe 52 and an air supply valve is provided in the middle of the pipe 14 for taking in outside air. When the temperature of the exhaust gas is equal to or higher than the threshold value, the air supply valve may be opened to reduce the temperature of the exhaust gas. At this time, it is preferable to operate the air supply valve (solenoid valve) based on the measurement data of the thermometer using an arithmetic device such as a computer. Alternatively, a thermometer may be installed at the outlet 51 b of the heavy oil J, and the supply valve may be controlled to open and close based on the measurement data of the temperature of the heavy oil J.

As a reference example, an asphalt plant may be configured as follows.
That is, an asphalt plant that manufactures asphalt composite material, and supplies heavy oil to a deodorizing furnace that deodorizes by burning odor components contained in exhaust gas, and a device that uses heavy oil as fuel among the devices of the asphalt plant A fuel supply facility and a heat exchanger that performs heat exchange between the exhaust gas from the deodorization furnace and the heavy oil may be provided.
According to this structure, the fuel consumption of an asphalt plant can be improved by warming the heavy oil which is fuel using the exhaust gas from a deodorizing furnace.

  In addition, since the exhaust gas from a deodorizing furnace is high temperature, it is preferable to provide the exhaust gas temperature reduction equipment which reduces the temperature of the exhaust gas from a deodorizing furnace. As the exhaust gas temperature lowering equipment, the “exhaust gas temperature adjusting equipment” described above can be used.

It is a schematic structure figure showing an asphalt plant concerning a 1st embodiment. It is sectional drawing which showed the heat exchanger which concerns on 1st Embodiment, (a) is AA sectional drawing of (b), (b) is BB sectional drawing of (a). It is the schematic block diagram which showed the asphalt plant which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 Asphalt plant 2 Dryer 21 Drum 22 Burner 3 Cyclone 4 Bag filter 5, 5 'Heat exchanger 6 Fuel supply equipment 7 Deodorizing furnace 51 Heavy oil piping 52, 52' Exhaust gas piping 53 Heat sink 61 Heavy oil tank 62 Pump J heavy oil

Claims (7)

An asphalt plant for producing asphalt composites,
A dryer that heats the aggregate;
Of each apparatus of the asphalt plant, a fuel supply facility that supplies heavy oil to an apparatus that uses heavy oil as fuel,
An asphalt plant comprising: a heat exchanger that exchanges heat between the exhaust gas from the dryer and the heavy oil.   2. The asphalt plant according to claim 1, wherein the exhaust gas from the dryer is supplied to the heat exchanger after the temperature is lowered to 70 to 90 ° C. 3.   The asphalt plant according to claim 1 or 2, wherein the exhaust gas from the dryer is supplied to the heat exchanger after passing through a bag filter. The heat exchanger includes an exhaust gas pipe through which the exhaust gas flows,
One end of the exhaust gas pipe is connected to the exhaust side of the bag filter,
The asphalt plant according to claim 3, wherein the other end of the exhaust gas pipe is connected to an air supply side of the bag filter. The heat exchanger is
A heavy oil pipe through which the heavy oil flows;
5. The exhaust gas pipe according to claim 1, wherein the exhaust gas pipe is arranged inside the heavy oil pipe and has a linear shape through which the exhaust gas from the dryer flows. Asphalt plant according to item.   The asphalt plant according to claim 5, wherein a heat radiating plate is formed on an outer peripheral surface of the exhaust gas pipe.   The asphalt plant according to any one of claims 1 to 6, wherein the apparatus using fuel oil as a fuel is a dryer, a deodorizing furnace, or a hot oil heater.

Images