JP2023162682A - Asphalt plant and asphalt mixture manufacturing method - Google Patents

Abstract

To provide an asphalt plant that can reduce the amount of carbon dioxide emitted into the atmosphere in spite of using existing combustion equipment.SOLUTION: An asphalt plant 1 includes a recycled dryer 40 that heats asphalt pavement waste, a deodorizing furnace 50 that thermally decomposes odor components contained in the exhaust gas discharged from the recycled dryer 40, and a drying furnace 60 that dries the dehydrated sludge by bringing the exhaust gas discharged from the deodorizing furnace 50 into contact with the dehydrated sludge to form sludge powder. When the dehydrated sludge comes into contact with the exhaust gas discharged from the deodorizing furnace 50, calcium hydroxide, which is the main component of dehydrated sludge, consolidates carbon dioxide contained in exhaust gas. Thereby, the amount of carbon dioxide emitted from the asphalt plant 1 into the atmosphere can be reduced.SELECTED DRAWING: Figure 1

Description

The present invention relates to an asphalt plant and a method for producing an asphalt mixture.

Asphalt plants that manufacture asphalt mixtures use new aggregates (hereinafter referred to as "new materials"), which are raw materials for asphalt mixtures, and waste materials (hereinafter referred to as (referred to as "waste material") is subjected to heat treatment. Heat treatment is performed mainly by burning fossil fuels in dryers of asphalt plants. Exhaust gas discharged from the dryer during the heat treatment is released into the atmosphere through the chimney.

On the other hand, in recent years, efforts have been made to reduce emissions of greenhouse gases such as carbon dioxide contained in exhaust gases in order to prevent global warming. Therefore, the development of asphalt plants that reduce carbon dioxide emissions is progressing. For example, by using pulverized coal derived from woody biomass as fuel in the combustion equipment of an asphalt plant, it is possible to reduce carbon dioxide emissions from the viewpoint of carbon neutrality. An asphalt plant equipped with a pulverized coal burner that uses pulverized coal as fuel is described in, for example, Patent Document 1.

Japanese Patent Application Publication No. 2019-027647

In order to handle woody biomass fuel in an existing asphalt plant, it is necessary to install dedicated combustion equipment compatible with the fuel. However, it is difficult to modify the combustion equipment of existing asphalt plants to be compatible with woody biomass fuel, so it is necessary to replace them with dedicated combustion equipment. Therefore, using wood-based biomass fuel in an existing asphalt plant requires a large amount of cost and man-hours.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide an asphalt plant that can reduce the amount of carbon dioxide emitted into the atmosphere while using existing combustion equipment.

In order to solve the above problems, the first invention of the present application is an asphalt plant, which includes a regeneration dryer that heats asphalt pavement waste material, and a deodorization furnace that thermally decomposes odor components contained in the exhaust gas discharged from the regeneration dryer. , a drying furnace that dries the dehydrated sludge by bringing the exhaust gas discharged from the deodorizing furnace into contact with the dehydrated sludge to form powdered sludge powder.

A second invention of the present application is the asphalt plant of the first invention, further comprising one or more filtering and dust collectors that filter dust from exhaust gas generated in the asphalt plant, and the filtering and dust collector is configured to filter dust from exhaust gas generated in the asphalt plant. The apparatus further includes a collection section that collects the sludge powder contained in the exhaust gas.

A third invention of the present application is the asphalt plant of the second invention, which includes: a sludge powder storage bin for storing the sludge powder formed in the drying furnace; a new material dryer for heating the new aggregate; The sludge powder supply unit mixes the sludge powder stored in the sludge powder storage bin into the exhaust gas discharged from the new material dryer, and at least one of the filtration and dust collectors This is a new material filtration and dust collector that filters dust and the sludge powder from exhaust gas discharged from a new material dryer.

A fourth invention of the present application is the asphalt plant according to the third invention, in which the sludge powder collected in the collection section of the new material filtration dust collector is returned to the sludge powder storage bin. It further comprises: and.

A fifth invention of the present application is the asphalt plant according to any one of the first to fourth inventions, in which the drying furnace further includes crushing blades that crush the dehydrated sludge.

The sixth invention of the present application is a method for producing an asphalt mixture, which includes a) a step of heating asphalt pavement waste material, b) a step of thermally decomposing the odor components contained in the exhaust gas generated in the step a), and c) A step of drying the dehydrated sludge by contacting it with the exhaust gas that has passed through the step b) to form a powdered sludge powder; and d) a step of mixing the sludge powder with asphalt.

According to the first to sixth inventions of the present application, when the dehydrated sludge comes into contact with the exhaust gas discharged from the deodorizing furnace, calcium hydroxide, which is the main component of the dehydrated sludge, removes carbon dioxide contained in the exhaust gas. to be fixed. This makes it possible to reduce the amount of carbon dioxide emitted into the atmosphere from the asphalt plant.

In particular, according to the third invention of the present application, sludge powder containing unreacted calcium hydroxide is brought into contact with the exhaust gas discharged from the new material dryer, and carbon dioxide contained in the exhaust gas is fixed. This makes it possible to further reduce the amount of carbon dioxide emitted into the atmosphere from the asphalt plant.

In particular, according to the fourth invention of the present application, the sludge powder collected from the new material filtration and dust collector is brought into contact with the exhaust gas again while unreacted calcium hydroxide remains. Thereby, the amount of carbon dioxide contained in the exhaust gas fixed can be increased, and the amount of carbon dioxide discharged into the atmosphere from the asphalt plant can be further reduced.

In particular, according to the fifth invention of the present application, dewatered sludge can be crushed more finely. Therefore, by increasing the specific surface area (contact area with exhaust gas) of the sludge powder, more carbon dioxide can be fixed. Furthermore, the time required to dry the dewatered sludge can be reduced.

It is a diagram showing the configuration of an asphalt plant. FIG. 2 is a cross-sectional view of the filtration and dust collector taken at a substantially central position in the width direction along a plane perpendicular to the width direction. FIG. 2 is a cross-sectional view taken along a plane perpendicular to the width direction of the filter dust collector at a position approximately ⅓ on the right side of the surface where the clean gas discharge section is provided. FIG. 2 is a cross-sectional view of the filtration and dust collector taken at a substantially central position in the longitudinal direction along a plane perpendicular to the longitudinal direction. It is a figure which shows the situation when exhaust gas is introduced into a filter dust collector. It is a figure which shows the situation when compressed air is introduced into a filter dust collector. It is a figure showing the composition of the asphalt plant concerning a modification.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

<1. Embodiment>
FIG. 1 is a diagram showing the configuration of an asphalt plant 1. As shown in FIG. This asphalt plant 1 produces an asphalt mixture by mixing new material, heat-regenerated waste material (recycled material), asphalt, and stone powder. As shown in FIG. 1, the asphalt plant 1 includes a new material hopper 10, a waste material hopper 20, a new material dryer 30, a regeneration dryer 40, a deodorizing furnace 50, a drying furnace 60, and a first filtration dust collector 70. , a second filtration and dust collector 80, a plant main body 90, a sludge powder storage bin 160, and a chimney 190.

The new material hopper 10 is a facility that temporarily stores new aggregate (hereinafter referred to as "new material") brought into the asphalt plant 1. The new material dryer 30 is a device that heat-processes the new material supplied from the new material hopper 10. The new material dryer 30 includes a drum 31, a machine stand 32, and a burner 33. The drum 31 is located at the center of the new material dryer 30. The machine stand 32 is provided to rotatably support the drum 31 from below. The burner 33 is located at one end of the new material dryer 30. The new material dryer 30 is connected to the plant main body 90 by a vertical conveyance device 101. The new material dryer 30 is connected to the second filtration and dust collector 80 through a first exhaust flue 111 .

The new material hopper 10 supplies new material to the drum 31 of the new material dryer 30. The new material dryer 30 has raking blades (not shown) on the inner circumference of the drum 31. The scraping blades are rotated at a predetermined speed by a drive device (not shown) and stir the new material supplied to the drum 31. The burner 33 heats the new material supplied to the drum 31 to a predetermined temperature. The vertical conveyance device 101 conveys the heated new material to the plant main body 90. Exhaust gas generated by heating the new material is discharged to the first exhaust flue 111. The exhaust gas generated by heating the new material contains dust generated as the new material burns.

The first exhaust flue 111 is provided with a first inertial dust collector 121 such as a cyclone. The first inertial dust collector 121 separates dust with a relatively large particle size from among the dust contained in the exhaust gas. The separated dust having a relatively large particle size is fed into the vertical conveyance device 101 by a return conveyance means (not shown). The vertical conveyance device 101 conveys the separated dust having a relatively large particle size to the plant main body 90 together with the new material that has been heated and dried. The exhaust gas discharged from the first inertial dust collector 121 is introduced into the second filtration dust collector 80 downstream.

The waste material hopper 20 is a facility for temporarily storing waste materials carried into the asphalt plant 1. The regeneration dryer 40 is a device in the asphalt plant 1 that heat-processes waste material supplied from the waste material hopper 20 to form recycled material. The regenerated dryer 40 includes a drum 41, a machine stand 42, a burner 43, a regenerated material storage bin 44, and a regenerated material measuring tank 45. The drum 41 is located between the burner 43 and the recycled material storage bin 44. The machine stand 42 is provided to rotatably support the drum 41 from below. Burner 43 is located at one end of regeneration dryer 40 . A recycled material storage bin 44 is located at the other end of the recycled dryer 40 . The recycled material measuring tank 45 is located at the lower end of the recycled material storage bin 44 . The regeneration dryer 40 is connected to a deodorizing furnace 50 by a second exhaust flue 112. The regeneration dryer 40 is connected to the plant main body 90 through an input chute 102.

The waste material hopper 20 supplies waste material to the drum 41 of the regeneration dryer 40. The regenerating dryer 40 has scraping blades (not shown) on the inner circumference of the drum 41. The scraping blades are rotated at a predetermined speed by a drive device (not shown) and stir the waste material supplied to the drum 41. The burner 43 heats the waste material supplied to the drum 41 to a predetermined temperature. The recycled material storage bin 44 temporarily stores heated waste material. The recycled material measuring tank 45 measures a predetermined amount of waste material stored in the recycled material storage bin 44 and supplies it to the input chute 102 . The input chute 102 transports a predetermined amount of waste material to the plant main body 90. Exhaust gas generated by heating the waste material is discharged from the recycled material storage bin 44 to the second exhaust flue 112.

A second inertial dust collector 122 such as a cyclone and a first exhaust fan 131 are provided in the second exhaust flue 112 in this order from the regeneration dryer 40 side. The first exhaust fan 131 sucks and exhausts the exhaust gas containing dust generated during the heating regeneration process in the regeneration dryer 40, and the dust contained in the exhaust gas is separated by the second inertial dust collector 122. The separated dust is put into an arbitrary place, such as the recycled material storage bin 44. The first exhaust fan 131 sucks the air in the second exhaust flue 112 and causes the exhaust gas generated by the regeneration dryer 40 to flow into the second exhaust flue 112 .

The deodorizing furnace 50 is a device that thermally decomposes odor components contained in exhaust gas generated by heating waste materials. Specifically, the deodorizing furnace 50 reheats the exhaust gas introduced from the second exhaust flue 112 at a high temperature to decompose odor components contained in the exhaust gas. The deodorizing furnace 50 includes a burner 51 and a retention chamber 52. The deodorizing furnace 50 is connected to the drying furnace 60 through a third exhaust flue 113.

The burner 51 maintains the temperature inside the deodorizing furnace 50 at a high temperature of about 800° C., which is higher than the temperature inside the regeneration dryer 40, for example. The retention chamber 52 retains the exhaust gas introduced from the second exhaust flue 112 for at least 1 second or more and 2 seconds or less. Thereby, the odor components contained in the exhaust gas are thermally decomposed. Thereafter, the exhaust gas is discharged to the third exhaust flue 113.

A heat exchanger 141 is provided between the second exhaust flue 112 and the third exhaust flue 113. The heat exchanger 141 performs heat exchange between the exhaust gas discharged from the deodorizing furnace 50 and the exhaust gas before being introduced into the deodorizing furnace 50. Thereby, the exhaust gas passing through the second exhaust flue 112 can be introduced into the deodorizing furnace 50 in a state where the temperature is raised in advance.

The drying furnace 60 is a device that dries dehydrated sludge obtained by dehydrating concrete sludge. Concrete sludge is the sludge that is generated when cleaning mixers, additive trucks, etc. at a ready-mixed concrete manufacturing plant. Concrete sludge is generally disposed of after separation of sand and cement contained in the sludge, followed by dehydration treatment using a filter press or the like. In addition, returned concrete received from surplus ready-mixed concrete at the pouring site, and residual ready-mixed concrete that was not shipped from the ready-mixed concrete manufacturing factory are generally subjected to the separation and dewatering treatment described above. After that, it will be discarded in the same way. However, in this embodiment, these dewatered sludges are utilized in the asphalt plant 1 without being disposed of.

The drying furnace 60 includes a dehydrated sludge receiving section 61 and a kiln main body 62. The drying oven 60 is connected to the first filtration and dust collector 70 by a fourth exhaust flue 114.

Dewatered sludge is carried into the asphalt plant 1 from a concrete plant or the like, and is supplied to the dewatered sludge receiving section 61. The dewatered sludge receiving section 61 supplies the received dehydrated sludge to the kiln main body 62. Further, the exhaust gas discharged from the deodorizing furnace 50 to the third exhaust flue 113 is supplied from the third exhaust flue 113 to the kiln main body 62.

The kiln main body 62 has a substantially cylindrical shape and rotates around the axis of the cylinder. A plurality of raking blades 621 are arranged on the inner wall of the kiln main body 62. When the kiln main body 62 rotates, the raking blades 621 rotate while raking up the dewatered sludge deposited at the bottom of the kiln main body 62. The dewatered sludge scraped upward by the scraping blades 621 falls toward the bottom of the kiln body 62 due to its own weight. This allows the dewatered sludge to be uniformly stirred. Further, the dewatered sludge is crushed by the impact of falling to the bottom of the kiln body 62.

The dehydrated sludge is agitated by the scraping blades 621 and thereby comes into uniform contact with the exhaust gas supplied from the third exhaust flue 113. As described above, the exhaust gas supplied from the third exhaust flue 113 is heated to a high temperature in the deodorizing furnace 50. Therefore, the dehydrated sludge is heated and dried by contacting the exhaust gas in the kiln main body 62. In addition, the dehydrated sludge changes from a lump to a powder during the process of being dried while being stirred.

Calcium hydroxide, which is the main component of dehydrated sludge, changes into calcium carbonate by reacting with carbon dioxide. Therefore, the dehydrated sludge is dried by the heat of the exhaust gas, and also fixes carbon dioxide in the exhaust gas. Thereby, the amount of carbon dioxide discharged into the atmosphere from the asphalt plant 1 can be reduced.

In addition, this makes it possible to more effectively utilize the exhaust heat of the deodorizing furnace 50, which is normally discharged from the chimney 190 at a high temperature even after the heat is recovered by the heat exchanger 141, thereby improving energy usage efficiency. I can do it.

Furthermore, the high temperature exhaust heat of the deodorizing furnace 50 becomes in a temperature range that can be introduced into the first filtration and dust collector 70 through heat exchange with the dehydrated sludge in the drying furnace 60. Thereby, it is possible to further reduce the amount of carbon dioxide in the first filtration and dust collector 70, which will be described later, while suppressing burnout of the filter cloth 73.

Furthermore, since the dehydrated sludge becomes powder inside the kiln main body 62, its specific surface area increases, and therefore the contact area with carbon dioxide in the exhaust gas increases. This allows the dewatered sludge to fix more carbon dioxide. Furthermore, since the dewatered sludge is in powder form, it becomes easier to transport the dehydrated sludge. In the following description, the dried dehydrated sludge powder will be referred to as "sludge powder 9."

Note that the kiln main body 62 does not need to be cylindrical or rotary as long as it can introduce exhaust gas and dry the dewatered sludge.

The exhaust gas introduced into the drying furnace 60 passes through the kiln main body 62 and is then discharged to the first filter dust collector 70 via the fourth exhaust flue 114. Further, the sludge powder 9 is discharged from the kiln main body 62 to the first sludge powder conveying section 103.

The first filtration and dust collector 70 is a device that filters dust from the exhaust gas discharged from the drying furnace 60. The first filtration and dust collector 70 includes a compressed air introduction section 71 , an exhaust gas introduction section 72 , a filter cloth 73 , a clean gas discharge section 74 , a dust screw 75 , and a powder discharge section 76 . The first filtration and dust collector 70 is connected to a sludge powder storage bin 160 through a first sludge powder conveying section 103 . The first filtration and dust collector 70 is connected to the chimney 190 by a fifth exhaust flue 115. FIG. 2 is a cross-sectional view of the first filtration and dust collector 70 taken at a substantially central position in the width direction along a plane perpendicular to the width direction. The first filtration and dust collector 70 is divided into an exhaust gas chamber 77 and a clean gas chamber 78 by a partition 79. On the exhaust gas chamber 77 side, an exhaust gas introduction section 72, a dust screw 75, and a powder discharge section 76 are provided. A compressed air introduction section 71 and a clean gas discharge section 74 are provided on the clean gas chamber 78 side.

FIG. 3 is a cross-sectional view of the first filtration and dust collector 70, taken along a plane perpendicular to the lateral direction, at approximately ⅓ of the right side of the surface where the clean gas discharge section 74 is provided. FIG. 4 is a cross-sectional view of the first filtration and dust collector 70 taken at a substantially central position in the longitudinal direction along a plane perpendicular to the longitudinal direction. The filter cloth 73 is a collection part that collects dust, and has a substantially cylindrical shape with an open upper end. As shown in FIGS. 2 to 4, rows of a plurality of filter cloths 73 are provided at regular intervals between the front end and the rear end of the first filtration and dust collector 70. Moreover, as shown in FIG. 4, the filter cloth 73 is provided so as to connect the exhaust gas chamber 77 and the clean gas chamber 78. The gas in the first filtration and dust collector 70 can flow between the exhaust gas chamber 77 and the clean gas chamber 78 only through the filter cloth 73. Specifically, the exhaust gas introduced into the exhaust gas chamber 77 passes through the filter cloth 73 and flows into the clean gas chamber 78, and the compressed air introduced into the clean gas chamber 78 passes through the filter cloth 73 and becomes the exhaust gas. It flows into chamber 77.

FIG. 5 is a diagram showing a situation when exhaust gas is introduced into the first filtration and dust collector 70. The exhaust gas introduced into the first filtration and dust collector 70 includes sludge powder 9 that has flowed from the drying furnace 60 into the fourth exhaust flue 114 together with the exhaust gas, and dust generated during the heating regeneration process in the regeneration dryer 40. It is included. The thick arrows in FIG. 5 indicate an example of the direction in which exhaust gas flows. The exhaust gas introduced from the exhaust gas introduction section 72 flows into the exhaust gas chamber 77. The exhaust gas then flows through filter cloth 73 into clean gas chamber 78 . At this time, the filter cloth 73, which is a collection section, collects the sludge powder 9 and dust contained in the exhaust gas.

FIG. 6 is a diagram showing a situation when compressed air is introduced into the first filtration and dust collector 70. The thick arrows in FIG. 6 indicate an example of the direction in which compressed air flows. When a certain amount of dust and sludge powder 9 is collected on the surface of filter cloth 73, compressed air introduction section 71 injects compressed air into clean gas chamber 78. Dust and sludge powder 9 adhering to the surface of the filter cloth 73 on the exhaust gas chamber 77 side are blown off to the lower part of the exhaust gas chamber 77 by the impact of the jet of compressed air. Thereafter, the dust and sludge powder 9 are conveyed by the dust screw 75 to the powder discharge section 76, and are discharged from the powder discharge section 76 to the first sludge powder conveyance section 103.

Further, the exhaust gas filtered by the filter cloth 73 is discharged from the clean gas discharge section 74 to the fifth exhaust flue 115. Note that, since the sludge powder 9 is in contact with the exhaust gas also inside the fourth exhaust flue 114 and the first filtration/dust collector 70, the sludge powder 9 fixes carbon dioxide during this time as well.

The first sludge powder conveying section 103 supplies the sludge powder 9 discharged from the drying oven 60 and the sludge powder 9 discharged from the first filtration/dust collector 70 to the sludge powder storage bin 160 .

A second exhaust fan 132 is provided in the fifth exhaust flue 115. The exhaust gas discharged from the first filter dust collector 70 to the fifth exhaust flue 115 passes through the second exhaust fan 132 and is discharged from the chimney 190 into the atmosphere. The second exhaust fan 132 sucks air passing through the fifth exhaust flue 115 to exhaust the exhaust gas in the drying furnace 60 from the chimney 190 into the atmosphere. The amount of carbon dioxide contained in the exhaust gas discharged from the chimney 190 is reduced by the amount fixed in the sludge powder 9 in the drying furnace 60 and the first filtration and dust collector 70.

The sludge powder storage bin 160 stores the sludge powder 9 supplied from the first sludge powder transport section 103. A second sludge powder transport section 104 is connected to the sludge powder storage bin 160. The other end of the second sludge powder conveying section 104 joins the first exhaust flue 111. A sludge powder supply section 170 is provided at the confluence of the second sludge powder conveyance section 104 and the first exhaust flue 111.

The second sludge powder transport section 104 transports the sludge powder 9 stored in the sludge powder storage bin 160 to the sludge powder supply section 170 . Specifically, the second sludge powder conveyance section 104 generates an airflow from the sludge powder storage bin 160 toward the sludge powder supply section 170 using an air pump (not shown). The sludge powder 9 is transported from the sludge powder storage bin 160 to the sludge powder supply section 170 by this airflow. At this time, the sludge powder 9 is preferably dry to the extent that it can be transported by the airflow of the air pump, and more preferably in an absolutely dry state. Note that the transport method of the second sludge powder transport section 104 is not limited to transport using an air pump, and the sludge powder 9 may be transported using, for example, a screw feeder. In this case, even if water remains in the sludge powder 9, the second sludge powder conveying section 104 stably transports the sludge powder 9 from the sludge powder storage bin 160 to the sludge powder supply section 170. It can be transported up to

Sludge powder supply section 170 supplies sludge powder 9 to first exhaust flue 111 . As the sludge powder supply section 170, for example, a rotary valve is used. As a result, the sludge powder 9 is mixed into the exhaust gas passing through the first exhaust flue 111. Note that as the sludge powder supply section 170, a nozzle that injects the sludge powder 9 to the first exhaust flue 111 may be used instead of the rotary valve.

It is preferable that the sludge powder supply section 170 is provided closer to the second filtration and dust collector 80 than the first inertial dust collector 121 in the first exhaust flue 111 . If it is provided closer to the new material dryer 30 than the first inertial dust collector 121, the sludge powder 9 supplied to the first exhaust flue 111 can be separated by the first inertial dust collector 121 depending on its particle size. There is sex. In that case, the sludge powder 9 will be mixed into the dust of the new material transported from the first inertial dust collector 121 to the stone dust storage bin 94, which is not preferable.

The second filtration and dust collector 80 is a device that filters dust from the exhaust gas discharged from the new material dryer 30. The "second filtration and dust collector 80" corresponds to the "new material filtration and dust collector" of the present invention. The exhaust gas introduced into the second filtration and dust collector 80 contains sludge powder 9 and dust generated as the new material is burned in the new material dryer 30. The second filter dust collector 80 includes a compressed air introduction section 81, an exhaust gas introduction section 82, a filter cloth 83, a clean gas discharge section 84, a dust screw 85, a powder discharge section 86, an exhaust gas chamber 87, a clean gas chamber 88, and a partition 89. Equipped with The details of the compressed air introduction section 81, exhaust gas introduction section 82, filter cloth 83, clean gas discharge section 84, dust screw 85, powder discharge section 86, exhaust gas chamber 87, clean gas chamber 88, and partition 89 are as follows. Since they are the same as the air introduction section 71, exhaust gas introduction section 72, filter cloth 73, clean gas discharge section 74, dust screw 75, powder discharge section 76, exhaust gas chamber 77, clean gas chamber 78, and partition 79, the explanation will be repeated. omitted. The second filtration and dust collector 80 is connected to the plant main body 90 by a stone powder conveying section 105. The second filtration and dust collector 80 is connected to the chimney 190 through the sixth exhaust flue 116.

In the second filter dust collector 80 , the sludge powder 9 collected on the filter cloth 83 comes into contact with the exhaust gas passing through the filter cloth 83 . As described above, the sludge powder 9 collected on the filter cloth 83 is obtained by fixing carbon dioxide in the exhaust gas discharged from the deodorizing furnace 50 when being dried in the drying furnace 60. However, the sludge powder 9 may still contain calcium hydroxide that has not reacted with carbon dioxide. Therefore, the calcium hydroxide remaining in the sludge powder 9 fixes carbon dioxide in the exhaust gas passing through the filter cloth 83. Thereby, the amount of carbon dioxide contained in the exhaust gas generated in the new material dryer 30 can be reduced.

Therefore, by introducing the sludge powder 9 together with the exhaust gas into the second filtration and dust collector 80, the amount of carbon dioxide discharged into the atmosphere from the asphalt plant 1 can be further reduced. In addition, since the sludge powder 9 is in contact with the exhaust gas while moving from the sludge powder supply section 170 to the filter cloth 83, the sludge powder 9 also fixes carbon dioxide during that time.

The powder discharge section 86 discharges the sludge powder 9 and dust that have been brushed off from the filter cloth 83 to the stone powder conveyance section 105 . The stone powder transport unit 105 transports the sludge powder 9 and dust to the stone powder storage bin 94 of the plant main body 90. Calcium carbonate produced by the reaction between calcium hydroxide contained in the sludge powder 9 and carbon dioxide in the exhaust gas is the same component as the stone powder that is the material of the asphalt mixture. Therefore, the sludge powder 9 in which carbon dioxide is fixed can be reused as stone powder.

Note that the asphalt plant 1 may include a sludge powder return section 180 that returns the sludge powder 9 brushed off from the filter cloth 83 to the sludge powder storage bin 160. The sludge powder return section 180 branches from the stone powder transport section 105 and is connected to the sludge powder storage bin 160 . The sludge powder return section 180 returns the sludge powder 9 discharged from the powder discharge section 86 to the sludge powder storage bin 160. The returned sludge powder 9 passes through the second sludge powder conveyance section 104 again, is supplied from the sludge powder supply section 170 to the first exhaust flue 111, and is introduced into the second filter dust collector 80. As a result, the sludge powder 9 comes into contact with the exhaust gas again, and the calcium hydroxide remaining in the sludge powder 9 fixes carbon dioxide in the exhaust gas. Therefore, the amount of carbon dioxide emitted into the atmosphere from the asphalt plant 1 can be further reduced. Further, the sludge powder return unit 180 may repeat returning the sludge powder 9 to the sludge powder storage bin 160 a predetermined number of times. Thereafter, the stone powder conveyance unit 105 may convey the sludge powder 9 to the stone powder storage bin 94. Thereby, carbon dioxide can be more effectively fixed in the sludge powder 9.

A third exhaust fan 133 is provided in the sixth exhaust flue 116. The exhaust gas discharged from the clean gas discharge section 84 passes through the third exhaust fan 133 and is discharged from the chimney 190 into the outside air. The third exhaust fan 133 maintains the pressure inside the equipment located between the new material dryer 30 and the third exhaust fan 133 at negative pressure. Thereby, it is possible to suppress leakage of the new material in the new material dryer 30 or the exhaust gas from the new material dryer 30 to the outside of the new material dryer 30 .

The plant main body 90 is a facility that mixes heat-treated new material, heat-regenerated waste material (recycled material), stone powder, and asphalt to produce an asphalt mixture. The plant main body 90 includes a vibrating sieve 91, an aggregate storage bin 92, an aggregate measuring tank 93, a stone powder storage bin 94, a stone powder measuring tank 95, a molten asphalt tank 96, a supply pump 97, and an asphalt measuring tank. 98 and a mixer 99.

The vibrating sieve 91 receives fresh material supplied from the vertical conveyance device 101. The vibrating sieve 91 sieves the received new material and supplies it to the aggregate storage bin 92 according to particle size. The aggregate measuring tank 93 weighs the new materials stored in the aggregate storage bins 92 according to particle size, and supplies them to the mixer 99.

The stone powder storage bin 94 temporarily stores the stone powder transported into the asphalt plant 1 and the sludge powder 9 transported from the stone powder transport section 105. In the following description, the stone powder carried into the asphalt plant 1 and the sludge powder 9 carried from the stone powder conveying section 105 are collectively referred to as "stone powder." The stone powder measuring tank 95 measures a predetermined amount of stone powder stored in the stone powder storage bin 94 and supplies it to the mixer 99 .

The molten asphalt tank 96 temporarily stores asphalt, which is a material for an asphalt mixture. Supply pump 97 transports asphalt from molten asphalt tank 96 to asphalt metering tank 98 . The asphalt measuring tank 98 measures the asphalt supplied from the asphalt conveying section and supplies it to the mixer 99.

The mixer 99 mixes new material supplied from the aggregate measuring tank 93, waste material supplied from the recycled material measuring tank 45, stone powder supplied from the stone powder measuring tank 95, and asphalt supplied from the asphalt measuring tank 98. are mixed for a predetermined period of time to produce the desired asphalt mixture.

As described above, the asphalt plant 1 of this embodiment can be constructed by adding additional equipment to an already constructed asphalt plant. Therefore, this embodiment provides an asphalt plant that reduces the amount of carbon dioxide emitted into the atmosphere while reducing costs and man-hours compared to replacing existing equipment such as combustion equipment. It is possible to do so.

<2. Modified example>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

In the above embodiment, the asphalt plant 1 manufactured an asphalt mixture using new materials and waste materials as aggregates. However, the asphalt plant 1 may use only waste materials as aggregate to produce an asphalt mixture.

For example, when only waste material is used as aggregate, the new material dryer 30 and the second filtration/dust collector 80 do not operate because the new material is not heated. At this time, the sludge powder storage bin 160 may temporarily store the sludge powder 9 without supplying the sludge powder 9 to the second sludge powder conveying section 104. Then, when the second filtration and dust collector 80 operates next time, the stored sludge powder 9 may be supplied to the second sludge powder conveyance section 104.

In the above embodiment, the kiln main body 62 of the drying oven 60 was equipped with the raking blades 621. However, in addition to the raking blades 621, the kiln main body 62 may further include crushing blades 622 that crush the dewatered sludge. FIG. 7 is a diagram showing the configuration of an asphalt plant 1 according to a modification. As shown in FIG. 7, in this modification, the drying oven 60 further includes a plurality of crushing blades 622 and a crushing blade drive motor 63.

As shown in FIG. 7, the plurality of crushing blades 622 extend in the radial direction of the kiln body 62 from the central axis of the kiln body 62. The crushing blade 622 is rotated by a crushing blade drive motor 63 around the end of the kiln main body 62 on the central axis side. As described in the above embodiment, the dewatered sludge lifted up by the scraping blades 621 due to the rotation of the kiln main body 62 falls to the bottom of the kiln main body 62 due to its own weight. Thereafter, in this modification, the rotating crushing blades 622 come into contact with the dewatered sludge that has fallen, thereby crushing the dehydrated sludge. This allows the dewatered sludge to be crushed more finely. Therefore, the time required to dry the dewatered sludge can be reduced.

Further, in the above embodiment, the second sludge powder transport section 104 was connected to the sludge powder storage bin 160, and the other end of the second sludge powder transport section 104 joined the first exhaust flue 111. . Further, the second filtration and dust collector 80 was connected to the plant main body 90 by a stone powder conveying section 105. As a result, the sludge powder 9 supplied to the sludge powder storage bin 160 was supplied to the second filtration dust collector 80 and then transported to the stone powder storage bin 94 of the plant main body 90 by the stone powder transport section 105. However, the sludge powder storage bin 160 may be connected to the stone powder storage bin 94 of the plant body 90. As a result, the sludge powder 9 supplied to the sludge powder storage bin 160 is directly supplied to the stone powder storage bin 94 of the plant main body 90. The sludge powder 9 supplied from the sludge powder storage bin 160 to the stone powder storage bin 94 is used as stone powder.

Further, in the embodiment described above, the second sludge powder conveying section 104 merged with the first exhaust flue 111. However, the second sludge powder conveyance section 104 may be connected to the second filtration and dust collector 80.

Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate to the extent that no contradiction occurs.

The present invention can be used in asphalt plants to reduce the amount of carbon dioxide emitted into the atmosphere.

1: Asphalt plant 9: Sludge powder 10: New material hopper 20: Waste material hopper 30: New material dryer 40: Regeneration dryer 50: Deodorizing furnace 60: Drying furnace 70: First filtration dust collector 71: Compressed air introduction section 72: Exhaust gas Introduction section 73: Filter cloth 74: Clean gas discharge section 75: Dust screw 76: Powder discharge section 77: Exhaust gas chamber 78: Clean gas chamber 79: Partition 80: Second filtration dust collector 90: Plant main body 121: First inertial dust collector 122: Second inertial dust collector 160: Sludge powder storage bin 170: Sludge powder supply section 180: Sludge powder return section 190: Chimney 621: Scraping blade 622: Crushing blade

Claims (6)

A recycled dryer that heats asphalt pavement waste,
a deodorizing furnace that thermally decomposes odor components contained in the exhaust gas discharged from the regeneration dryer;
a drying furnace that dries the dehydrated sludge by bringing the exhaust gas discharged from the deodorizing furnace into contact with the dehydrated sludge to form powdered sludge powder;
Asphalt plant equipped with The asphalt plant according to claim 1,
further comprising one or more filtration and dust collectors that filter dust from exhaust gas generated in the asphalt plant,
The filter dust collector is an asphalt plant including a collection section that collects the sludge powder contained in the exhaust gas generated in the asphalt plant. The asphalt plant according to claim 2,
a sludge powder storage bin for storing the sludge powder formed in the drying oven;
A new material dryer that heats new aggregate,
a sludge powder supply unit that mixes the sludge powder stored in the sludge powder storage bin into the exhaust gas discharged from the new material dryer;
Furthermore,
The asphalt plant, wherein at least one of the filtration and dust collectors is a new material filtration and dust collector that filters dust and the sludge powder from exhaust gas discharged from the new material dryer. The asphalt plant according to claim 3,
a sludge powder return section that returns the sludge powder collected in the collection section of the new material filtration and dust collector to the sludge powder storage bin;
Asphalt plant further equipped with. The asphalt plant according to any one of claims 1 to 4,
The asphalt plant, wherein the drying furnace further includes crushing blades that crush the dehydrated sludge. a) heating asphalt pavement waste;
b) a step of thermally decomposing the odor components contained in the exhaust gas generated in step a);
c) drying the dehydrated sludge by contacting it with the exhaust gas that has passed through the step b) to form a powdered sludge powder;
d) mixing the sludge powder with asphalt;
A method for producing an asphalt mixture comprising:

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