Asphalt plant and asphalt mixture manufacturing method

Abstract

To provide an asphalt plant capable of reducing the amount of carbon dioxide discharged into the atmosphere while using an existing combustion facility.SOLUTION: An asphalt plant 1 includes: a dryer for heating at least one of new aggregate and asphalt pavement waste material; a sludge powder supply part 170 for mixing sludge powder obtained by drying dehydrated sludge with exhaust gas discharged from the dryer in a state of containing dust; and a filter dust collector 80 for filtering dust from the exhaust gas, the filter dust collector 80 including a collection part for collecting sludge powder contained in the exhaust gas. When the sludge powder collected by the collection unit and the exhaust gas discharged from the dryer are brought into contact with each other, calcium hydroxide, which is a main component of the sludge powder, fixes carbon dioxide contained in the exhaust gas. This makes it possible to reduce the amount of carbon dioxide discharged from the asphalt plant 1 into the atmosphere.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 materials"), which are the raw materials for asphalt mixtures, and waste asphalt pavement materials (hereinafter referred to as "waste materials") dug up during road construction and other work are subjected to a 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 dryer that heats at least one of new aggregate and asphalt pavement waste, a sludge powder supply unit that mixes powdered sludge powder made from dried dewatered sludge into exhaust gas discharged from the dryer in a state containing dust, and a filter dust collector that filters dust from the exhaust gas, and the filter dust collector comprises a collection unit that collects the sludge powder contained in the exhaust gas.

[0008] The second invention of the present application is the asphalt plant of the first invention, wherein the dryer includes a recycled dryer that heats the asphalt pavement waste material, and the plant is equipped with a deodorizing furnace that heats the odor contained in the exhaust gas discharged from the recycled dryer, a dryer that dries the dewatered sludge to form the sludge powder, a heat transfer section that is provided between the deodorizing furnace and the dryer and that transfers the heat of the exhaust gas discharged from the deodorizing furnace to the dryer, a sludge powder storage bin that stores the sludge powder formed by the dryer, and a sludge powder transport section that transports the sludge powder from the sludge powder storage bin to the sludge powder supply section, and the dryer dries the dewatered sludge using the heat transferred from the heat transfer section.

[0009] A third invention of the present application is the asphalt plant of the second invention, wherein the heat transfer section includes a heat storage device that stores heat of the exhaust gas discharged from the deodorizing furnace.

[0010] The fourth invention of the present application is an asphalt plant according to the third invention, wherein the heat storage device is provided with a heat exchanger that stores a heat medium which is a fluid and performs heat exchange between the exhaust gas discharged from the deodorizing furnace and the heat medium, and the heat transfer section is provided with a first circulation circuit that circulates the heat medium between the heat exchanger and the heat storage device, and a second circulation circuit that circulates the heat medium between the heat storage device and the dryer.

[0011] The fifth invention of the present application is an asphalt plant according to any one of the second to fourth inventions, further comprising a sludge powder return section that returns the sludge powder collected in the collection section from the filter dust collector to the sludge powder storage bin.

[0012] A sixth aspect of the present invention is the asphalt plant according to any one of the first to fifth aspects, further comprising a sludge crushing device for crushing the dewatered sludge.

[0013] The seventh invention of the present application is a method for producing an asphalt mixture, comprising the steps of: a) heating at least one of new aggregate and waste asphalt pavement; b) mixing a powdered sludge powder obtained by drying dewatered sludge into the exhaust gas discharged in step a); c) introducing the exhaust gas mixed with the sludge powder into a filter dust collector; and d) recovering the sludge powder collected in a collection section provided in the filter dust collector from the collection section and mixing it with asphalt. [Effects of the Invention]

[0014] According to the first to seventh inventions of the present application, when the sludge powder collected by the collection unit comes into contact with the exhaust gas discharged from the dryer, calcium hydroxide, the main component of the sludge powder, immobilizes the carbon dioxide contained in the exhaust gas, thereby reducing the amount of carbon dioxide emitted into the atmosphere from asphalt plants.

[0015] In particular, according to the second aspect of the present invention, the heat of the exhaust gas generated in the deodorizing furnace is used to dry the dewatered sludge, thereby reducing the energy consumption required to dry the dewatered sludge.

[0016] In particular, according to the third aspect of the present invention, the heat of the exhaust gas generated in the deodorizing furnace can be temporarily stored. As a result, even if the deodorizing furnace and the dryer are operated at different times, the heat of the exhaust gas generated in the deodorizing furnace can be used to dry the dewatered sludge. This reduces the energy consumption required to dry the dewatered sludge.

[0017] In particular, according to the fifth aspect of the present invention, the sludge powder recovered from the filter dust collector with unreacted calcium hydroxide remaining therein can be reacted again with carbon dioxide, thereby increasing the amount of carbon dioxide contained in the exhaust gas that can be fixed.

[0018] In particular, according to the sixth aspect of the present invention, the specific surface area of ​​the sludge powder is increased, thereby making it possible to increase the amount of carbon dioxide contained in the exhaust gas that can be fixed. [Brief explanation of the drawings]

[0019] [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. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0021] <1. Embodiment> Figure 1 shows the configuration of an asphalt plant 1. This asphalt plant 1 produces an asphalt mixture by mixing new wood, waste wood, asphalt, and stone powder. As shown in Figure 1, the asphalt plant 1 includes a new wood hopper 10, a waste wood hopper 20, a new wood dryer 30, a regeneration dryer 40, a deodorizing furnace 50, a heat storage device 60, a dryer 71, a sludge powder storage bin 72, a filter dust collector 80, a plant main body 90, and a chimney 190.

[0022] The new material hopper 10 is a facility for temporarily storing 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 filter dust collector 80 by a first exhaust flue 111.

[0023] 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.

[0024] The first exhaust flue 111 is equipped with a first inertial dust collector 121, such as a cyclone, on the upstream side. 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 a vertical conveying device 101. 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 a filter dust collector 80 downstream.

[0025] 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. The regenerative dryer 40 comprises a drum 41, a machine base 42, a burner 43, a regenerative material storage bin 44, and a regenerative material measuring tank 45. The drum 41 is located between the burner 43 and the regenerative material storage bin 44. The machine base 42 is arranged to rotatably support the drum 41 from below. The burner 43 is located at one end of the regenerative dryer 40. The regenerative material storage bin 44 is located at the other end of the regenerative dryer 40. The regenerative material measuring tank 45 is located at the lower end of the regenerative 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 .

[0026] 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.

[0027] A second inertial dust collector 122 such as a cyclone is provided in the second exhaust flue 112. The first exhaust fan 131 sucks and exhausts the dust-containing exhaust gas generated during the thermal 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 dumped into a desired destination such as a regenerated material storage bin 44.

[0028] The deodorizing furnace 50 is a device that heats and decomposes odors 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 odors 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 chimney 190 by the third exhaust flue 113.

[0029] 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 that of 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, thereby breaking down the odor contained in the exhaust gas. The exhaust gas is then discharged into the third exhaust flue 113.

[0030] A first heat exchanger 141 is provided between the second exhaust flue 112 and the third exhaust flue 113. The first 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.

[0031] The heat storage device 60 is a device that stores the heat of the exhaust gas discharged from the deodorizing furnace 50. The heat storage device 60 stores a heat medium therein. Oil is used as the heat medium. Note that the heat medium may also be a fluid generally used as a heat medium, such as water or air. A first circulation circuit 151 is connected to the heat storage device 60. A first circulation pump 161 is provided in the first circulation circuit 151. A second heat exchanger 142 is provided between the first circulation circuit and the third exhaust flue. The heat storage device 60 is connected to the dryer 71 by a second circulation circuit 152. A second circulation pump 162 is provided in the second circulation circuit 152.

[0032] The first circulation pump 161 circulates the heat medium flowing through the first circulation circuit 151 between the second heat exchanger 142 and the heat storage device 60. The second heat exchanger 142 exchanges heat between the heat medium and the exhaust gas discharged from the deodorizing furnace 50. The exhaust gas cooled by the second heat exchanger 142 is discharged into the atmosphere through a chimney 190. The heat medium heated by the second heat exchanger 142 circulates through the first circulation circuit 151 and flows into the heat storage device 60. The heat storage device 60 stores the heated heat medium.

[0033] The second circulation pump 162 circulates the heat medium flowing through the second circulation circuit 152. The heat storage device 60 circulates the heated heat medium through the second circulation circuit 152 as necessary, thereby transferring heat to the dryer 71.

[0034] As described above, the heat storage device 60 can temporarily store the thermal energy of the exhaust gas generated in the deodorizing furnace 50. As a result, even if the time period during which the deodorizing furnace 50 operates differs from the time period during which the dryer 71 operates, the heat of the exhaust gas generated in the deodorizing furnace 50 can be reused in the dryer 71 by temporarily storing the heat of the exhaust gas in the heat storage device 60. This makes it possible to reduce the energy consumption required for the sludge drying process described below.

[0035] The dryer 71 is a device that dries dewatered sludge that has been obtained by dewatering concrete sludge. Concrete sludge is sludge that is generated when cleaning mixers, aggregator 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 the like. However, in this embodiment, this dewatered sludge is not disposed of but is instead utilized in the asphalt plant 1.

[0036] Dewatered sludge is transported from a concrete plant or the like to the sphalt plant 1 and supplied to the dryer 71. The dryer 71 dries the dewatered sludge using a heat medium circulating through the second circulation circuit 152 as a heat source. A jacket heater, for example, is used to dry the dewatered sludge. The dried dewatered sludge is preferably in powder form. This facilitates transportation of the dewatered sludge. Furthermore, the specific surface area of ​​the dewatered sludge is increased, thereby increasing the amount of carbon dioxide immobilized (described later). In the following description, the dried dewatered sludge powder is referred to as "sludge powder 9." The dryer 71 then discharges the sludge powder 9 into a sludge powder storage bin 72. In this embodiment, the dryer 71 continuously receives and dries the dewatered sludge. However, the dryer 71 may also receive a predetermined amount of dewatered sludge in batches and dry each batch separately. The dryer 71 may also be equipped with an auxiliary heating device to improve the efficiency of heating the dewatered sludge.

[0037] Furthermore, the dryer 71 may be equipped with a sludge crushing device that crushes the dewatered sludge into even smaller pieces. This makes it easier to transport the sludge powder. Also, the larger the specific surface area of ​​the sludge powder, the greater the amount of carbon dioxide that can be fixed by the sludge powder, as described below.

[0038] The sludge powder storage bin 72 stores the sludge powder 9 supplied from the dryer 71. A sludge powder conveying unit 103 is connected to the sludge powder storage bin 72. The other end of the sludge powder conveying unit 103 merges with the first exhaust flue 111. A sludge powder supplying unit 170 is provided at the junction of the sludge powder conveying unit 103 and the first exhaust flue 111. The sludge powder conveying unit 103 conveys the sludge powder 9 stored in the sludge powder storage bin 72 to the sludge powder supplying unit 170. Specifically, the sludge powder conveying unit 103 generates an airflow from the sludge powder storage bin 72 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 72 to the sludge powder supplying unit 170 by this airflow. At this time, the sludge powder 9 is preferably dry enough to be transportable by the airflow of an air pump, and more preferably in an absolutely dry state. The transport method of the sludge powder transport unit 103 is not limited to transport by an air pump, and the sludge powder 9 may be transported using, for example, a screw feeder. In this case, even if moisture remains in the sludge powder 9, the sludge powder transport unit 103 can stably transport the sludge powder 9 from the sludge powder storage bin 72 to the sludge powder supply unit 170.

[0039] 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. Note that instead of a rotary valve, a nozzle that injects the sludge powder 9 into the first exhaust flue 111 may be used as the sludge powder supply unit 170.

[0040] The sludge powder supply unit 170 is preferably provided on the first exhaust flue 111 closer to the 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.

[0041] The 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, and a powder discharge section 86. The filter dust collector 80 is connected to the plant main body 90 via a stone powder conveying section 104. The filter dust collector 80 is connected to a chimney 190 via a fourth exhaust flue 114. FIG. 2 is a cross-sectional view of the filter dust collector 80 taken at approximately the center of its width along a plane perpendicular to the width. The filter dust collector 80 is divided into an exhaust gas chamber 87 and a clean gas chamber 88 by a partition 89. The exhaust gas inlet 82, the dust screw 85, and the powder discharge section 86 are provided on the exhaust gas chamber 87 side. The compressed air inlet 81 and the clean gas discharge section 84 are provided on the clean gas chamber 88 side.

[0042] FIG. 3 is a cross-sectional view of the filter dust collector 80 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 84 is provided. FIG. 4 is a cross-sectional view of the filter dust collector 80 taken along a plane perpendicular to the long direction at approximately the center of the longitudinal direction. The filter cloth 83 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 83 is provided at regular intervals between the front and rear ends of the filter dust collector 80. As shown in FIG. 4, the filter cloths 83 are provided to connect the exhaust gas chamber 87 and the clean gas chamber 88. Gas within the filter dust collector 80 can circulate between the exhaust gas chamber 87 and the clean gas chamber 88 only through the filter cloths 83. Specifically, the exhaust gas introduced into the exhaust gas chamber 87 passes through the filter cloth 83 and flows into the clean gas chamber 88, and the compressed air introduced into the clean gas chamber 88 passes through the filter cloth 83 and flows into the exhaust gas chamber 87.

[0043] FIG. 5 is a diagram showing the state when exhaust gas is introduced into the filter dust collector 80. The thick arrows in FIG. 5 indicate an example of the direction in which exhaust gas flows. Exhaust gas introduced from an exhaust gas inlet 82 flows into an exhaust gas chamber 87. Next, the exhaust gas flows into a clean gas chamber 88 through a filter cloth 83. At this time, the filter cloth 83, which serves as a collection section, captures sludge powder 9 and dust contained in the exhaust gas. Thereafter, the exhaust gas filtered by the filter cloth 83 is discharged from a clean gas discharge section 84.

[0044] FIG. 6 shows the state when compressed air is introduced into the filter dust collector 80. 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 83, the compressed air inlet 81 injects compressed air into the clean gas chamber 88. The dust and sludge powder 9 adhering to the surface of the filter cloth 83 facing the exhaust gas chamber 87 is knocked down into the exhaust gas chamber 87 by the impact of the compressed air injection. The dust and sludge powder 9 are then transported by the dust screw 85 to the powder discharge section 86, from which they are discharged to the stone powder transport section 104.

[0045] Calcium hydroxide, the main component of the sludge powder 9, reacts with carbon dioxide to convert to calcium carbonate. Therefore, the sludge powder 9 collected by the filter cloth 83 comes into contact with the exhaust gas passing through the filter cloth 83, thereby immobilizing the carbon dioxide in the exhaust gas. At this time, the larger the specific surface area of ​​the sludge powder, the greater the amount of carbon dioxide immobilized. This makes it possible to 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, so the sludge powder 9 can immobilize carbon dioxide during this time as well.

[0046] 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 104. The stone powder conveying unit 104 conveys the sludge powder 9 and dust to a stone powder storage bin 94 in the plant main body 90. Calcium carbonate, which is produced by the reaction between calcium hydroxide contained in the sludge powder 9 and carbon dioxide in the exhaust gas, has the same components as stone powder, which is an ingredient in asphalt mixtures. Therefore, the sludge powder 9 with the carbon dioxide fixed therein can be reused as stone powder.

[0047] The sludge powder 9 discharged to the stone powder conveying section 104 may contain sludge powder that has not been in sufficient contact with the exhaust gas and has not sufficiently immobilized carbon dioxide. For this reason, a sludge powder return section 180 may be provided that returns the sludge powder brushed off from the filter cloth 83 to the sludge powder storage bin 72. The sludge powder return section 180 branches off from the stone powder conveying section 104 and is connected to the sludge powder storage bin 72. The sludge powder return section 180 returns the sludge powder discharged from the powder discharge section 86 to the sludge powder storage bin 72. The returned sludge powder passes through the sludge powder conveying section 103 again, is supplied from the sludge powder supply section 170 to the first exhaust flue 111, and is introduced into the filter dust collector 80. As a result, the sludge powder comes into contact with the exhaust gas again, and the calcium hydroxide remaining in the sludge powder immobilizes the carbon dioxide in the exhaust gas. This makes it possible to further reduce the amount of carbon dioxide emitted into the atmosphere from the asphalt plant 1. Furthermore, the sludge powder return unit 180 may repeat the return of the sludge powder to the sludge powder storage bin 72 a predetermined number of times. Thereafter, the stone powder transport unit 104 may transport the sludge powder to the stone powder storage bin 94. This allows carbon dioxide to be more effectively fixed in the sludge powder.

[0048] A second exhaust fan 132 is provided in the fourth exhaust flue 114. The exhaust gas discharged from the clean gas discharge section 84 passes through the second exhaust fan 132 and is discharged into the outside air from a chimney 190. The second exhaust fan 132 maintains a negative pressure within the equipment located between the new material dryer 30 and the second exhaust fan 132. This makes it possible to prevent the new material and exhaust gas within the new material dryer 30 from leaking out of the new material dryer 30.

[0049] Plant body 90 is a facility for producing an asphalt mixture by mixing heat-treated new wood, heat-treated waste wood, 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.

[0050] 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.

[0051] 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 104. 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 104 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.

[0052] 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.

[0053] The mixer 99 produces an asphalt mixture by mixing new material supplied from the aggregate measuring tank 93, waste material supplied from the waste material measuring tank, stone powder supplied from the stone powder measuring tank 95, and asphalt supplied from the asphalt measuring tank 98 for a predetermined period of time.

[0054] 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.

[0055] <2. Variations> Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0056] 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 either new material or waste material as aggregate to produce an asphalt mixture.

[0057] For example, when only waste materials are used as aggregate, the new materials are not heat-treated, and therefore the new material dryer 30 and the filter dust collector 80 are not operated. At this time, the sludge powder storage bin 72 may temporarily store the sludge powder 9 without supplying it to the sludge powder conveying section 103. Then, the next time the filter dust collector 80 is operated, the stored sludge powder 9 may be supplied to the sludge powder conveying section 103.

[0058] In the above embodiment, the third exhaust flue 113 is connected to the chimney 190, so that the flue gas discharged from the deodorizing furnace 50 is discharged into the atmosphere from the chimney 190. However, instead of being connected to the chimney 190, the third exhaust flue 113 may be joined to the first exhaust flue 111 between the first inertial dust collector 121 and the filter dust collector 80. In this case, in addition to the flue gas discharged from the new material dryer 30, the flue gas discharged from the deodorizing furnace 50 flows into the filter dust collector 80. As a result, the flue gas discharged from the deodorizing furnace 50 also comes into contact with the sludge powder 9, and the sludge powder 9 immobilizes the carbon dioxide in the flue gas discharged from the deodorizing furnace 50. Therefore, the amount of carbon dioxide discharged from the asphalt plant 1 can be further reduced.

[0059] In the above embodiment, the heat storage device 60 stores a heat medium therein. The heat storage device 60 is connected to the first circulation circuit 151, and stores heat by circulating a heat medium through the first circulation circuit 151. The heat storage device 60 is connected to the second circulation circuit 152, and transfers heat to the dryer 71 by circulating a heat medium through the second circulation circuit 152. However, the heat storage device 60 may have a solid heat storage medium such as a ceramic material, and the heat storage medium may be connected to the second heat exchanger 142 and the dryer 71. The heat storage medium may be used to store heat from the second heat exchanger 142 or transfer heat to the dryer 71. At least one of the first circulation circuit 151 and the second circulation circuit 152 may be used in combination with a heat storage medium to store heat from the second heat exchanger 142 or transfer heat to the dryer 71.

[0060] In the above embodiment, the second heat exchanger 142, the first circulation circuit 151, the second circulation circuit 152, and the heat storage device 60 are provided between the deodorizing furnace 50 and the dryer 71, and constitute a heat transfer unit that transfers heat from the exhaust gas discharged from the deodorizing furnace 50 to the dryer 71. However, the heat storage device 60 does not necessarily have to be provided. In this case, the first circulation circuit 151 and the second circulation circuit 152 are directly connected to form a single circulation circuit that connects the second heat exchanger 142 and the dryer 71. The heat transfer unit transfers heat from the second heat exchanger 142 to the dryer 71 by circulating a heat medium through the circulation circuit. Note that the heat transfer unit may transfer heat from the second heat exchanger 142 to the dryer 71 using a heat-transferable solid material, such as a ceramic material, instead of a circulation circuit.

[0061] In the above embodiment, the sludge powder conveying section 103 merges with the first exhaust flue 111. However, the sludge powder conveying section 103 may be connected to the filter dust collector 80.

[0062] 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]

[0063] The present invention can be used in asphalt plants to reduce the amount of carbon dioxide emitted into the atmosphere. [Explanation of symbols]

[0064] 1: Asphalt plant 9: Sludge powder 10: New wood hopper 20: Waste material hopper 30: New wood dryer 31: Drums 32: Machine stand 33: Burner 40: Regenerated dryer 41: Drums 42: Machine stand 43: Burner 44: Recycled material storage bin 45:Recycled material measuring tank 50: Deodorizing furnace 51: Burner 52: Retention chamber 60: Heat storage device 71: Dryer 72: Sludge powder storage bin 80:Filtration dust collector 81: Compressed air introduction section 82: Exhaust gas inlet 83:Filter cloth 84:Clean gas discharge section 85: Dust screw 86: Powder discharge section 87: Exhaust gas chamber 88: Clean gas chamber 89: Divider 90: Plant body 91: Vibration sieve 92: Aggregate storage bin 93: Aggregate measuring tank 94: Stone powder storage bin 95: Stone powder measuring tank 96: Molten asphalt tank 97: Supply pump 98: Asphalt measuring tank 99: Mixer 101: Vertical conveying device 102: Shot 103: Sludge powder transport section 104: Stone powder conveyance section 111: First exhaust flue 112: Second exhaust flue 113: Third exhaust flue 114: 4th exhaust flue 121: 1st inertial dust collector 122:Second inertial dust collector 131: 1st exhaust fan 132:Second exhaust fan 141: 1st heat exchanger 142:Second heat exchanger 151: 1st circulation circuit 152:Second circulation circuit 161: First circulation pump 162: Second circulation pump 170: Sludge powder supply section 180: Sludge powder return section 190: Chimney

Claims

1. a dryer for heating at least one of the new aggregate and the waste asphalt pavement; a sludge powder supply unit that mixes powdered sludge, which is obtained by drying dewatered sludge derived from concrete sludge and contains calcium hydroxide as a main component, into the exhaust gas discharged from the dryer in a state containing dust; a filter dust collector that filters dust from the exhaust gas; Equipped with The filter dust collector is a collecting section for collecting the sludge powder contained in the exhaust gas; Equipped with The dryer comprises: A regenerative dryer that heats the waste asphalt pavement Including, a deodorizing furnace for heating odors contained in the exhaust gas discharged from the regenerative dryer; a dryer for drying the dewatered sludge to form the sludge powder; a heat transfer section provided between the deodorizing furnace and the dryer, for transferring heat of the exhaust gas discharged from the deodorizing furnace to the dryer; a sludge powder storage bin for storing the sludge powder formed in the dryer; a sludge powder conveying unit that conveys the sludge powder from the sludge powder storage bin to the sludge powder supply unit; Equipped with The dryer is an asphalt plant that dries dewatered sludge using heat transferred from the heat transfer section.

2. The asphalt plant according to claim 1, The heat transfer unit is a heat storage device that stores heat of the exhaust gas discharged from the deodorizing furnace. Asphalt plant equipped with:

3. The asphalt plant according to claim 2, The heat storage device stores a heat medium that is a fluid, a heat exchanger for exchanging heat between the exhaust gas discharged from the deodorizing furnace and the heat medium; Equipped with The heat transfer portion is a first circulation circuit that circulates the heat medium between the heat exchanger and the heat storage device; a second circulation circuit that circulates the heat medium between the heat storage device and the dryer; Asphalt plant equipped with:

4. An asphalt plant according to any one of claims 1 to 3, a sludge powder return section that returns the sludge powder collected in the collection section from the filter dust collector to the sludge powder storage bin; An asphalt plant further equipped with:

5. An asphalt plant according to any one of claims 1 to 4, Sludge crushing equipment for crushing dewatered sludge An asphalt plant further equipped with:

6. a) heating at least one of new aggregate and waste asphalt pavement; b) a step of mixing powdered sludge powder containing calcium hydroxide as a main component, which is obtained by drying dewatered sludge derived from concrete sludge, into the exhaust gas discharged in the step a); c) introducing the exhaust gas mixed with the sludge powder into a filter dust collector; d) recovering the sludge powder collected in the collection section provided in the filter dust collector from the collection section and mixing it with asphalt; and The step a) a-1) Heating the waste asphalt pavement Including, e) a step of heating the odor contained in the exhaust gas discharged in the step a-1); f) drying the dewatered sludge to form the sludge powder; and In the step f), the dewatered sludge is dried using the heat of the exhaust gas discharged in the step e).

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