Asphalt plant and asphalt mixture manufacturing method

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

[Technical Field]

[0001] The present invention relates to an asphalt plant and an asphalt mixture manufacturing method. [Background technology]

[0002] In asphalt plants that manufacture asphalt mixtures, new aggregates (hereinafter referred to as "new aggregates"), which are the raw materials for asphalt mixtures, and waste materials (hereinafter referred to as "waste materials"), which are asphalt pavement blocks excavated during road construction and other work, crushed to a specified particle size, are subjected to heat treatment. The heat treatment is carried out in the asphalt plant's dryer, mainly by burning fossil fuels. The exhaust gases emitted from the dryer during the heat treatment are released into the atmosphere through a chimney.

[0003] Meanwhile, 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. Accordingly, development of asphalt plants that reduce carbon dioxide emissions has progressed. 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 perspective of carbon neutrality. An asphalt plant equipped with a pulverized coal burner that uses pulverized coal as fuel is described, for example, in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-027647 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to handle woody biomass fuel in an existing asphalt plant, it is necessary to install dedicated combustion equipment that is compatible with the fuel. However, because it is difficult to modify the combustion equipment of an existing asphalt plant to be compatible with woody biomass fuel, it is necessary to replace it with dedicated combustion equipment. Therefore, using woody biomass fuel in an existing asphalt plant requires significant costs and labor.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide an asphalt plant that can reduce the amount of carbon dioxide emitted into the atmosphere while using existing combustion equipment. [Means for solving the problem]

[0007] In order to solve the above problems, the first invention of the present application is an asphalt plant comprising a regenerated dryer that heats asphalt pavement waste, a deodorizing furnace that thermally decomposes odorous components contained in the exhaust gas discharged from the regenerated dryer, and a drying furnace that dries the dewatered sludge by bringing the exhaust gas discharged from the deodorizing furnace into contact with the dewatered sludge, thereby forming a powdered sludge powder.

[0008] The second invention of the present application is an asphalt plant according to the first invention, further comprising one or more filter dust collectors that filter dust from exhaust gas generated in the asphalt plant, the filter dust collectors comprising a collection section that collects the sludge powder contained in the exhaust gas generated in the asphalt plant.

[0009] The third invention of the present application is an asphalt plant according to the second invention, further comprising a sludge powder storage bin for storing the sludge powder formed in the drying furnace, a new material dryer for heating new aggregate, and a sludge powder supply unit for mixing 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 filter dust collectors is a new material filter dust collector for filtering dust and the sludge powder from the exhaust gas discharged from the new material dryer.

[0010] The fourth invention of the present application is an asphalt plant of the third invention, further comprising a sludge powder return section that returns the sludge powder collected in the collection section of the new material filter dust collector to the sludge powder storage bin.

[0011] A fifth invention of the present application is the asphalt plant of any one of the first to fourth inventions, wherein the drying furnace further includes crushing blades for crushing the dewatered sludge.

[0012] The sixth invention of the present application is a method for producing an asphalt mixture, comprising the steps of: a) heating waste asphalt pavement; b) thermally decomposing odorous components contained in the exhaust gas generated in step a); c) drying dewatered sludge by contacting it with the exhaust gas that has been through step b) to form powdered sludge; and d) mixing the sludge powder with asphalt. [Effects of the Invention]

[0013] According to the first to sixth inventions of the present application, calcium hydroxide, a main component of the dewatered sludge, immobilizes carbon dioxide contained in the exhaust gas when the dewatered sludge comes into contact with the exhaust gas discharged from the deodorizing furnace, thereby reducing the amount of carbon dioxide emitted into the atmosphere from asphalt plants.

[0014] In particular, according to the third aspect of the present invention, sludge powder containing unreacted calcium hydroxide is brought into contact with the exhaust gas discharged from the new material dryer to immobilize the carbon dioxide contained in the exhaust gas, thereby further reducing the amount of carbon dioxide emitted into the atmosphere from the asphalt plant.

[0015] In particular, according to the fourth aspect of the present invention, the sludge powder recovered from the new material filter dust collector, with unreacted calcium hydroxide remaining, is brought into contact with the exhaust gas again, thereby increasing the amount of carbon dioxide contained in the exhaust gas that is fixed, and further reducing the amount of carbon dioxide emitted into the atmosphere from the asphalt plant.

[0016] In particular, according to the fifth aspect of the present invention, the dewatered sludge can be crushed into smaller pieces. Therefore, by increasing the specific surface area (contact area with the exhaust gas) of the sludge powder, more carbon dioxide can be fixed. Furthermore, the time required to dry the dewatered sludge can be reduced. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing the configuration of an asphalt plant. [Figure 2] 2 is a cross-sectional view of the filter dust collector taken at approximately the center in the widthwise direction along a plane perpendicular to the widthwise direction. FIG. [Figure 3] FIG. 2 is a cross-sectional view of the filter dust collector taken along a plane perpendicular to the short side, at approximately one-third of the right side of the surface where the clean gas discharge section is provided. [Figure 4] 2 is a cross-sectional view of the filter dust collector taken at approximately the center in the longitudinal direction along a plane perpendicular to the longitudinal direction. FIG. [Figure 5] FIG. 10 is a diagram showing a state when exhaust gas is introduced into a filter dust collector. [Figure 6] FIG. 10 is a diagram showing a state when compressed air is introduced into the filter dust collector. [Figure 7] FIG. 10 is a diagram showing the configuration of an asphalt plant according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0019] <1. Embodiment> Figure 1 is a diagram showing the configuration of an asphalt plant 1. This asphalt plant 1 produces an asphalt mixture by mixing new material, heated and regenerated waste material (recycled material), asphalt, and stone powder. As shown in Figure 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, a first filter dust collector 70, a second filter dust collector 80, a plant main body 90, a sludge powder storage bin 160, and a chimney 190.

[0020] The new material hopper 10 is a facility for temporarily storing new aggregate (hereinafter referred to as "new material") brought into the asphalt plant 1. The new material dryer 30 is a device for heat-treating the new material supplied from the new material hopper 10. The new material dryer 30 comprises a drum 31, a machine base 32, and a burner 33. The drum 31 is located in the center of the new material dryer 30. The machine base 32 is arranged to support the drum 31 from below so that it can rotate freely. 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 conveying device 101. The new material dryer 30 is connected to the second filter dust collector 80 by a first exhaust flue 111.

[0021] The new wood hopper 10 supplies new wood to the drum 31 of the new wood dryer 30. The new wood dryer 30 has a scraper blade (not shown) on the inner periphery of the drum 31. The scraper blade is rotated at a predetermined speed by a drive device (not shown) and agitates the new wood supplied to the drum 31. The burner 33 heats the new wood supplied to the drum 31 to a predetermined temperature. The vertical conveying device 101 transports the heated new wood to the plant main body 90. Exhaust gas generated by heating the new wood is discharged into the first exhaust flue 111. The exhaust gas generated by heating the new wood contains dust generated as the new wood is burned.

[0022] 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 relatively large particle diameters from the dust contained in the exhaust gas. The separated relatively large particle diameters are fed into the vertical conveying device 101 by a return conveying means (not shown). The vertical conveying device 101 conveys the separated relatively large particle diameters to the plant main body 90 together with new wood that has been heated and dried. The exhaust gas discharged from the first inertial dust collector 121 is introduced into the downstream second filter dust collector 80.

[0023] The waste material hopper 20 is a facility for temporarily storing waste material brought into the asphalt plant 1. The regenerative dryer 40 is a device in the asphalt plant 1 that heat-treats the waste material supplied from the waste material hopper 20 to form recycled material. The regenerative dryer 40 includes a drum 41, a machine base 42, a burner 43, a recycled material storage bin 44, and a recycled material measuring tank 45. The drum 41 is located between the burner 43 and the recycled material storage bin 44. The machine base 42 is configured to rotatably support the drum 41 from below. The burner 43 is located at one end of the regenerative dryer 40. The recycled material storage bin 44 is located at the other end of the regenerative dryer 40. The recycled material measuring tank 45 is located at the lower end of the recycled material storage bin 44. The regenerative dryer 40 is connected to the deodorizing furnace 50 by a second exhaust flue 112. The regenerative dryer 40 is connected to the plant body 90 by an input chute 102 .

[0024] The waste material hopper 20 supplies the waste material to the drum 41 of the regenerative dryer 40. The regenerative dryer 40 has a scraper blade (not shown) on the inner periphery of the drum 41. The scraper blade is rotated at a predetermined speed by a drive device (not shown) and agitates 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 regenerative material storage bin 44 temporarily stores the heated waste material. The regenerative material measuring tank 45 measures a predetermined amount of waste material stored in the regenerative material storage bin 44 and supplies it to the input chute 102. The input chute 102 transports the predetermined amount of waste material to the plant main body 90. Exhaust gas generated by heating the waste material is discharged from the regenerative material storage bin 44 to the second exhaust flue 112.

[0025] A second inertial dust collector 122 such as a cyclone and a first exhaust fan 131 are provided in this order on the second exhaust flue 112 from the regenerative dryer 40 side. The first exhaust fan 131 sucks in and exhausts exhaust gas containing dust generated in the thermal regeneration process in the regenerative dryer 40, and the dust contained in the exhaust gas is separated by the second inertial dust collector 122. The separated dust is thrown into an optional destination such as a regenerated material storage bin 44. The first exhaust fan 131 sucks in air from the second exhaust flue 112 and causes the exhaust gas generated in the regenerative dryer 40 to flow into the second exhaust flue 112.

[0026] The deodorizing furnace 50 is a device that thermally decomposes odorous 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 the odorous 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 by a third exhaust flue 113.

[0027] The burner 51 maintains the temperature inside the deodorizing furnace 50 at a high temperature of, for example, about 800°C, which is higher than the temperature inside the regenerative dryer 40. The retention chamber 52 retains the exhaust gas introduced from the second exhaust flue 112 for at least 1 second to 2 seconds. This causes the odorous components contained in the exhaust gas to be thermally decomposed. The exhaust gas is then discharged into the third exhaust flue 113.

[0028] A heat exchanger 141 is provided between the second exhaust flue 112 and the third exhaust flue 113. The heat exchanger 141 exchanges heat between the exhaust gas discharged from the deodorizing furnace 50 and the exhaust gas before being introduced into the deodorizing furnace 50. This allows the exhaust gas passing through the second exhaust flue 112 to be introduced into the deodorizing furnace 50 in a pre-heated state.

[0029] The drying furnace 60 is a device that dries dewatered sludge obtained by dewatering concrete sludge. Concrete sludge is sludge generated when cleaning mixers, agitator trucks, and other equipment at ready-mix concrete manufacturing plants. Concrete sludge is generally disposed of after separating the sand and cement contained in the sludge and then undergoing a dewatering process using a filter press or other device. Furthermore, returned concrete that is excess ready-mix concrete received at a pouring site, and residual concrete that is leftover ready-mix concrete that was not shipped from a ready-mix concrete manufacturing plant, are also generally disposed of in the same manner after undergoing the separation and dewatering process. However, in this embodiment, these dewatered sludges are not disposed of but are instead utilized in the asphalt plant 1.

[0030] The drying furnace 60 includes a dewatered sludge receiving section 61 and a kiln body 62. The drying furnace 60 is connected to the first filter dust collector 70 by a fourth exhaust flue 114.

[0031] Dewatered sludge is transported from a concrete plant or the like to the asphalt plant 1 and supplied to the dewatered sludge receiving section 61. The dewatered sludge receiving section 61 supplies the received dewatered sludge to the kiln main body 62. In addition, 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.

[0032] The kiln body 62 has a substantially cylindrical shape and rotates around the axis of the cylinder. A plurality of scraping blades 621 are arranged on the inner wall of the kiln body 62. When the kiln body 62 rotates, the scraping blades 621 rotate while scraping upward the dewatered sludge accumulated at the bottom of the kiln 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 agitated. The dewatered sludge is also crushed by the impact of falling to the bottom of the kiln body 62.

[0033] The dewatered sludge is stirred by the scraping blade 621, thereby coming into uniform contact with the flue gas supplied from the third exhaust flue 113. As described above, the flue gas supplied from the third exhaust flue 113 is heated to a high temperature in the deodorizing furnace 50. Therefore, the dewatered sludge is heated and dried by coming into contact with the flue gas in the kiln main body 62. Furthermore, the dewatered sludge changes from a lump state to a powder state during the process of being dried while being stirred.

[0034] Calcium hydroxide, the main component of dewatered sludge, reacts with carbon dioxide to turn into calcium carbonate. Therefore, the dewatered sludge is dried by the heat of the exhaust gas and fixes the carbon dioxide in the exhaust gas. This reduces the amount of carbon dioxide emitted into the atmosphere from the asphalt plant 1.

[0035] This also allows for more effective utilization of the exhaust heat from the deodorizing furnace 50, which is normally discharged from the chimney 190 at a high temperature even after heat recovery by the heat exchanger 141, thereby improving energy utilization efficiency.

[0036] Furthermore, the high-temperature exhaust heat from the deodorizing furnace 50 is subjected to heat exchange with the dehydrated sludge in the drying furnace 60, and reaches a temperature range that allows it to be introduced into the first filtration dust collector 70. This makes it possible to further reduce the amount of carbon dioxide in the first filtration dust collector 70, which will be described later, while suppressing burnout of the filter cloth 73.

[0037] Furthermore, the dewatered sludge becomes powdered inside the kiln body 62, which increases its specific surface area and therefore its contact area with the carbon dioxide in the exhaust gas. This allows the dewatered sludge to fix more carbon dioxide. In addition, the dewatered sludge becomes powdered, making it easier to transport. In the following explanation, the dried dewatered sludge powder is referred to as "sludge powder 9."

[0038] The kiln body 62 does not have to be cylindrical or rotary, as long as it can introduce exhaust gas and dry the dewatered sludge.

[0039] The exhaust gas introduced into the drying furnace 60 passes through the kiln body 62 and is then discharged to the first filter dust collector 70 via the fourth exhaust flue 114. In addition, the sludge powder 9 is discharged from the kiln body 62 to the first sludge powder conveying section 103.

[0040] The first filter dust collector 70 is a device that filters dust from the exhaust gas discharged from the drying furnace 60. The first filter dust collector 70 includes a compressed air inlet 71, an exhaust gas inlet 72, a filter cloth 73, a clean gas outlet 74, a dust screw 75, and a powder outlet 76. The first filter dust collector 70 is connected to a sludge powder storage bin 160 via a first sludge powder conveying section 103. The first filter dust collector 70 is connected to a chimney 190 via a fifth exhaust flue 115. FIG. 2 is a cross-sectional view of the first filter dust collector 70 taken along a plane perpendicular to the short side, approximately at the center of the short side. The first filter dust collector 70 is divided into an exhaust gas chamber 77 and a clean gas chamber 78 by a partition 79. The exhaust gas inlet 72, the dust screw 75, and the powder outlet 76 are provided on the exhaust gas chamber 77 side. On the clean gas chamber 78 side, a compressed air inlet 71 and a clean gas outlet 74 are provided.

[0041] FIG. 3 is a cross-sectional view of the first filter dust collector 70, taken along a plane perpendicular to the short direction, at approximately one-third 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 filter dust collector 70, taken along a plane perpendicular to the long direction, at approximately the center of the longitudinal direction. The filter cloth 73 is a dust collector that captures dust and has a generally cylindrical shape with an open upper end. As shown in FIGS. 2 to 4, a row composed of multiple filter cloths 73 is provided at regular intervals between the front and rear ends of the first filter dust collector 70. As shown in FIG. 4, the filter cloth 73 is provided to connect the exhaust gas chamber 77 and the clean gas chamber 78. Gas within the first filter dust collector 70 can circulate 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 flows into the exhaust gas chamber 77.

[0042] FIG. 5 is a diagram showing the state when exhaust gas is introduced into the first filter dust collector 70. The exhaust gas introduced into the first filter dust collector 70 contains sludge powder 9 that has flowed into the fourth exhaust flue 114 together with the exhaust gas from the drying furnace 60, and dust generated during the thermal regeneration process in the regeneration dryer 40. The thick arrows in FIG. 5 indicate an example of the direction in which the exhaust gas flows. The exhaust gas introduced from the exhaust gas inlet 72 flows into the exhaust gas chamber 77. Next, the exhaust gas passes through the filter cloth 73 and flows into the clean gas chamber 78. At this time, the filter cloth 73, which serves as a collector, captures the sludge powder 9 and dust contained in the exhaust gas.

[0043] FIG. 6 shows a state when compressed air is introduced into the first filter dust collector 70. The thick arrows in FIG. 6 indicate an example of the direction in which the compressed air flows. When a certain amount of dust and sludge powder 9 is collected on the surface of the filter cloth 73, the compressed air inlet 71 injects compressed air into the clean gas chamber 78. The dust and sludge powder 9 adhering to the surface of the filter cloth 73 facing the exhaust gas chamber 77 is knocked off to the bottom of the exhaust gas chamber 77 by the impact of the compressed air injection. The dust and sludge powder 9 are then transported by the dust screw 75 to the powder discharge section 76 and discharged from the powder discharge section 76 to the first sludge powder conveying section 103.

[0044] 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 the sludge powder 9 is also in contact with the exhaust gas inside the fourth exhaust flue 114 and inside the first filter dust collector 70, and the sludge powder 9 immobilizes carbon dioxide during this time as well.

[0045] The first sludge powder conveying section 103 supplies the sludge powder 9 discharged from the drying furnace 60 and the sludge powder 9 discharged from the first filter dust collector 70 to the sludge powder storage bin 160 .

[0046] 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 into the atmosphere from a chimney 190. The second exhaust fan 132 draws in air passing through the fifth exhaust flue 115, thereby discharging the exhaust gas in the drying furnace 60 into the atmosphere from the chimney 190. The amount of carbon dioxide contained in the exhaust gas discharged from the chimney 190 has been reduced by the amount that has been fixed in the sludge powder 9 in the drying furnace 60 and the first filter dust collector 70.

[0047] The sludge powder storage bin 160 stores the sludge powder 9 supplied from the first sludge powder conveying section 103. The sludge powder storage bin 160 is connected to the second sludge powder conveying section 104. The other end of the second sludge powder conveying section 104 merges with the first exhaust flue 111. A sludge powder supply section 170 is provided at the merger between the second sludge powder conveying section 104 and the first exhaust flue 111.

[0048] The second sludge powder conveying unit 104 conveys the sludge powder 9 stored in the sludge powder storage bin 160 to the sludge powder supplying unit 170. Specifically, the second sludge powder conveying unit 104 generates an air current from the sludge powder storage bin 160 to the sludge powder supplying unit 170 using an air pump (not shown). The sludge powder 9 is conveyed from the sludge powder storage bin 160 to the sludge powder supplying unit 170 by this air current. At this time, the sludge powder 9 is preferably dry enough to be conveyed by the air current of the air pump, and more preferably in an absolutely dry state. Note that the conveying method of the second sludge powder conveying unit 104 is not limited to conveyance by an air pump; for example, the sludge powder 9 may be conveyed using a screw feeder. In this case, even if moisture remains in the sludge powder 9, the second sludge powder conveying section 104 can stably convey the sludge powder 9 from the sludge powder storage bin 160 to the sludge powder supply section 170.

[0049] The sludge powder supply unit 170 supplies the sludge powder 9 to the first exhaust flue 111. A rotary valve, for example, is used as the sludge powder supply unit 170. This allows the sludge powder 9 to be mixed with the exhaust gas passing through the first exhaust flue 111. Note that instead of a rotary valve, a nozzle that sprays the sludge powder 9 into the first exhaust flue 111 may also be used as the sludge powder supply unit 170.

[0050] The sludge powder supply unit 170 is preferably provided on the first exhaust flue 111 closer to the second filter dust collector 80 than the first inertial dust collector 121. If it is provided on the new wood dryer 30 closer to the first inertial dust collector 121, the sludge powder 9 supplied to the first exhaust flue 111 may be separated by the first inertial dust collector 121 depending on its particle size. In that case, the sludge powder 9 will be mixed with the new wood dust transported from the first inertial dust collector 121 to the stone powder storage bin 94, which is not preferable.

[0051] The second filter dust collector 80 is a device that filters dust from the exhaust gas discharged from the new material dryer 30. The "second filter dust collector 80" corresponds to the "new material filter dust collector" of this invention. The exhaust gas introduced into the second filter 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 inlet 81, an exhaust gas inlet 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. The details of the compressed air inlet 81, exhaust gas inlet 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 the same as those of the compressed air inlet 71, exhaust gas inlet 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, so duplicated explanations will be omitted. The second filter dust collector 80 is connected to the plant main body 90 by a stone powder conveying section 105. The second filter dust collector 80 is connected to a chimney 190 by a sixth exhaust flue 116.

[0052] 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 formed by immobilizing carbon dioxide in the exhaust gas discharged from the deodorizing furnace 50 when it is dried in the drying furnace 60. However, calcium hydroxide that has not reacted with carbon dioxide may remain in the sludge powder 9. Therefore, the calcium hydroxide remaining in the sludge powder 9 immobilizes the carbon dioxide in the exhaust gas passing through the filter cloth 83. This makes it possible to reduce the amount of carbon dioxide contained in the exhaust gas generated in the new material dryer 30.

[0053] Therefore, by introducing the sludge powder 9 into the second filter dust collector 80 together with the exhaust gas, it is possible to further reduce the amount of carbon dioxide emitted into the atmosphere from the asphalt plant 1. Note that the sludge powder 9 is in contact with the exhaust gas even while traveling from the sludge powder supply section 170 to the filter cloth 83, and therefore the sludge powder 9 immobilizes carbon dioxide during this time as well.

[0054] The powder discharge unit 86 discharges the sludge powder 9 and dust that have been brushed off from the filter cloth 83 to the stone powder conveying unit 105. The stone powder conveying unit 105 conveys the sludge powder 9 and dust to a stone powder storage bin 94 in the plant main body 90. The calcium carbonate produced by the reaction between the calcium hydroxide contained in the sludge powder 9 and the carbon dioxide in the exhaust gas has the same components as the stone powder that is an ingredient in asphalt mixtures. Therefore, the sludge powder 9 with the carbon dioxide fixed therein can be reused as stone powder.

[0055] The asphalt plant 1 may also 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 off from the stone powder conveying 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 conveying 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 immobilizes the carbon dioxide in the exhaust gas. This further reduces the amount of carbon dioxide emitted into the atmosphere from the asphalt plant 1. Furthermore, the sludge powder returning unit 180 may repeat the return of the sludge powder 9 to the sludge powder storage bin 160 a predetermined number of times. Thereafter, the stone powder transporting unit 105 may transport the sludge powder 9 to the stone powder storage bin 94. This allows carbon dioxide to be fixed in the sludge powder 9 more effectively.

[0056] 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 into the outside air from the chimney 190. The third exhaust fan 133 maintains a negative pressure within the equipment located between the new material dryer 30 and the third exhaust fan 133. This makes it possible to prevent the new material or exhaust gas within the new material dryer 30 from leaking out of the new material dryer 30.

[0057] Plant body 90 is a facility for producing an asphalt mixture by mixing heat-treated new wood, heat-recycled waste wood (recycled material), stone powder, and asphalt. Plant body 90 includes a vibrating screen 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, an asphalt measuring tank 98, and a mixer 99.

[0058] The vibrating sieve 91 receives new material supplied from the vertical conveying device 101. The vibrating sieve 91 sifts the received new material and supplies it by grain size to aggregate storage bins 92. The aggregate measuring tank 93 weighs each piece of new material stored by grain size in the aggregate storage bins 92 and supplies it to the mixer 99.

[0059] The stone powder storage bin 94 temporarily stores the stone powder brought into the asphalt plant 1 and the sludge powder 9 transported from the stone powder transport unit 105. In the following explanation, the stone powder brought into the asphalt plant 1 and the sludge powder 9 transported from the stone powder transport unit 105 will be 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.

[0060] The molten asphalt tank 96 temporarily stores asphalt, which is a material for the asphalt mixture. A supply pump 97 transports the asphalt from the molten asphalt tank 96 to an asphalt metering tank 98. The asphalt metering tank 98 measures the asphalt supplied from the asphalt transport unit and supplies it to a mixer 99.

[0061] The mixer 99 produces the desired asphalt mixture by mixing new material supplied from the aggregate metering tank 93, waste material supplied from the recycled material metering tank 45, stone powder supplied from the stone powder metering tank 95, and asphalt supplied from the asphalt metering tank 98 for a predetermined period of time.

[0062] 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 can provide an asphalt plant that reduces the amount of carbon dioxide emitted into the atmosphere while reducing costs and labor compared to replacing existing equipment such as combustion equipment.

[0063] <2. Modifications> Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0064] In the above embodiment, the asphalt plant 1 uses new material and waste material as aggregate to produce an asphalt mixture. However, the asphalt plant 1 may use only waste material as aggregate to produce an asphalt mixture.

[0065] For example, when only waste material is used as aggregate, the new material is not heat-treated, and therefore the new material dryer 30 and the second filter dust collector 80 are not operated. At this time, the sludge powder storage bin 160 may temporarily store the sludge powder 9 without supplying it to the second sludge powder conveying section 104. Then, the next time the second filter dust collector 80 is operated, the stored sludge powder 9 may be supplied to the second sludge powder conveying section 104.

[0066] In the above embodiment, the kiln body 62 of the drying furnace 60 is equipped with a scraping blade 621. However, the kiln body 62 may further include a crushing blade 622 that crushes the dewatered sludge in addition to the scraping blade 621. FIG. 7 is a diagram showing the configuration of an asphalt plant 1 according to a modified example. As shown in FIG. 7, in this modified example, the drying furnace 60 further includes a plurality of crushing blades 622 and a crushing blade drive motor 63.

[0067] As shown in FIG. 7, multiple crushing blades 622 extend radially from the central axis of the kiln body 62. The crushing blades 622 are rotated by a crushing blade drive motor 63 around the end of the kiln body 62 on the central axis side. As described in the above embodiment, the dewatered sludge lifted by the scraping blades 621 due to the rotation of the kiln body 62 falls to the bottom of the kiln body 62 due to its own weight. In this modification, the rotating crushing blades 622 then come into contact with the falling dewatered sludge, crushing it. This allows the dewatered sludge to be crushed into smaller pieces. Therefore, the time required to dry the dewatered sludge can be reduced.

[0068] In the above embodiment, the second sludge powder conveying section 104 is connected to the sludge powder storage bin 160, and the other end of the second sludge powder conveying section 104 joins the first exhaust flue 111. The second filter dust collector 80 is connected to the plant main body 90 by the stone powder conveying section 105. As a result, the sludge powder 9 supplied to the sludge powder storage bin 160 is supplied to the second filter dust collector 80 and then conveyed to the stone powder storage bin 94 of the plant main body 90 by the stone powder conveying section 105. However, the sludge powder storage bin 160 may be connected to the stone powder storage bin 94 of the plant main 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.

[0069] In the above embodiment, the second sludge powder conveying section 104 merges with the first exhaust flue 111. However, the second sludge powder conveying section 104 may be connected to the second filter dust collector 80.

[0070] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate within the scope of not causing any contradiction. [Industrial Applicability]

[0071] The present invention can be used in asphalt plants to reduce the amount of carbon dioxide emitted into the atmosphere. [Explanation of symbols]

[0072] 1: Asphalt plant 9: Sludge powder 10: New wood hopper 20: Waste material hopper 30: New wood dryer 40: Regenerated dryer 50: Deodorizing furnace 60:Drying oven 70: 1st filtration dust collector 71: Compressed air introduction section 72: Exhaust gas inlet 73:Filter cloth 74:Clean gas discharge section 75: Dust screw 76: Powder discharge section 77: Exhaust gas chamber 78: Clean gas chamber 79: Divider 80:Second filtration dust collector 90: Plant body 121: 1st 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: Raking feather 622: Crushing blade

Claims

1. a regenerative dryer that heats waste asphalt pavement; a deodorizing furnace for thermally decomposing odorous components contained in the exhaust gas discharged from the regenerative dryer; a drying furnace that brings the exhaust gas discharged from the deodorizing furnace into contact with the dewatered sludge to dry the dewatered sludge and form a powdery sludge; An asphalt plant equipped with:

2. The asphalt plant according to claim 1, The asphalt plant further includes one or more filter dust collectors for filtering dust from the exhaust gas generated in the asphalt plant; The filter dust collector includes a collection unit that collects the sludge powder contained in exhaust gas generated in the asphalt plant.

3. 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 the 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, At least one of the filter dust collectors is a new material filter dust collector that filters dust and the sludge powder from the exhaust gas discharged from the new material dryer.

4. The asphalt plant according to claim 3, a sludge powder returning unit that returns the sludge powder collected in the collecting unit of the new material filter dust collector to the sludge powder storage bin; An asphalt plant that also includes:

5. An asphalt plant according to any one of claims 1 to 4, The drying furnace has a crushing blade for crushing the dewatered sludge. An asphalt plant that also includes:

6. a) heating waste asphalt pavement; b) a step of thermally decomposing odorous components contained in the exhaust gas generated in the step a); c) drying the dewatered sludge by contacting it with the exhaust gas that has been subjected to the b) step to form a powdery sludge; d) mixing the sludge powder with asphalt; An asphalt mixture manufacturing method comprising the steps of:

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