Deodorizing device and deodorizing method

Abstract

To provide a deodorizer and a deodorizing method excellent in heat exchanging efficiency, by applying a material causing no problem, for a heat storage material, even if degradation and damage occur due to heat shock, while forming a simple device structure.SOLUTION: Aggregate containers 13a-13e are continuously formed in vertical five steps. At the upper part of an input port 11 of the first aggregate container 13a, aggregate supply means 20, and at the lower part of a discharge port 12 of the fifth aggregate container 13e, aggregate cutout means 22 are provided. To the fourth aggregate container 13d, a first exhaust duct 4a continued to a recycle dryer 3 is connected; to the first aggregate container 13a, a second exhaust duct 4b continued to a stack 24 is connected; to the second aggregate container 13b, a combustion chamber 26 having a deodorizing burner 25 is connected; to the third aggregate container 13c, an exhaust gas supply duct 27 supplying the exhaust gas from recycle dryer 3 to the combustion chamber 26 is connected; and to the fifth aggregate container 13e, a combustion air supply duct 28 supplying ambient air sucked from the discharge port 12 to the deodorizing burner 25 is connected.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a deodorizing apparatus and a deodorizing method for combustion-decomposing odor components contained in exhaust gas from a recycled dryer of an asphalt plant.

Background Art

[0002] In an asphalt plant of an asphalt mixture manufacturing factory that manufactures an asphalt mixture, which is a road paving material, there are installed a virgin dryer for heating virgin materials, that is, new aggregates, and a recycled dryer for heating asphalt paving waste materials (hereinafter referred to as "waste materials"). When heating waste materials in the recycled dryer, exhaust gas containing odor components may be generated depending on the heating conditions. Therefore, a deodorizing furnace is installed in the middle of the exhaust duct of the recycled dryer, the odor components contained in the exhaust gas are introduced into the furnace, and combustion decomposition is performed at around about 800°C for deodorization treatment.

[0003] At this time, since the deodorized treatment gas discharged from the deodorizing furnace is at a high temperature and direct release into the atmosphere would result in an economic loss, a heat exchanger is installed in the deodorizing furnace to recover heat from the high-temperature deodorized treatment gas, and it is effectively used for preheating the gas to be treated (exhaust gas from the recycled dryer) before introduction into the deodorizing furnace, combustion air for the burner, etc. (see, for example, Patent Document 1).

[0004] However, since asphalt plants generally have a low operating rate and are often operated intermittently, in the heat exchanger of the deodorizing furnace, heating and cooling are repeatedly performed many times at short intervals. As a result, metal fatigue (heat shock) progresses relatively easily in a relatively short period, and it is inevitable to regularly replace the equipment. Therefore, as the heat exchanger installed in the deodorizing furnace of an asphalt plant, equipment with a lower device cost is often prioritized, and the heat exchange area is relatively small and inexpensive. For that reason, the deodorized treatment gas is discharged at a relatively high temperature of about 300 to 400°C, and the heat recovery is not necessarily sufficient.

[0005] On the other hand, an example of a deodorizing device with excellent heat exchange efficiency is a regenerative thermal deodorizing device (hereinafter referred to as "RTO" (Regenerative Thermal Oxidizer)). The RTO comprises a combustion chamber with a burner and two or more heat storage chambers communicating with the combustion chamber. Exhaust gas from a recycling dryer is supplied to one heat storage chamber for preheating, and the preheated exhaust gas is heated in the combustion chamber to combust and decompose odor components, while the deodorized gas is discharged after heat is recovered in the other heat storage chambers. Each of the heat storage chambers has, for example, a ceramic heat storage material with a honeycomb structure as a heat exchanger. Although it is more expensive than conventional heat exchangers with metal elements, it allows for a larger heat exchange area, which is advantageous for heat recovery (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-1996 [Patent Document 2] Japanese Patent Publication No. 2021-107615 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, as mentioned above, in asphalt plants where intermittent operation is unavoidable, even with the RTO, the heat storage material is still subjected to repeated heating and cooling at short intervals. Furthermore, ceramic heat storage materials do not have superior resistance to thermal shock. Therefore, in order to prevent the heat storage material from deteriorating or being damaged by thermal shock, it is necessary to preheat it slowly by suppressing the rate of heating. As a result, preheating takes a long time and consumes extra fuel, which may prevent the RTO from fully utilizing its inherently high heat exchange capacity. In addition, RTOs require a complex switching mechanism to perform the exchange of heat-dissipating gas and heat-receiving gas in multiple heat storage chambers, which is somewhat disadvantageous in terms of cost and maintenance.

[0008] In view of the above, the present invention aims to provide a deodorizing device and deodorizing method that employ a material for the heat storage material that is not affected even if it deteriorates or is damaged due to heat shock, and that has a simple device configuration while having excellent heat exchange efficiency. [Means for solving the problem]

[0009] To solve the above problems, the deodorizing device according to claim 1 of the present invention is a deodorizing device that burns and decomposes odor components in exhaust gas from a recycling dryer of an asphalt plant, and comprises five hollow aggregate containers arranged vertically in series, each having an inlet at the upper end and an outlet at the lower end, with the inlet and outlet of each adjacent aggregate container connected and communicating, with an aggregate supply means provided above the inlet of the first aggregate container counting from the upper side, and an aggregate cutting means provided below the outlet of the fifth aggregate container, and the fourth aggregate The material container is characterized by having a first exhaust duct connected to the recycling dryer at the upper side of the material container, a second exhaust duct connected to the chimney via an exhaust fan at the upper side of the first aggregate container, a combustion chamber having a deodorizing burner at the upper side of the second aggregate container, an exhaust gas supply duct that supplies exhaust gas from the recycling dryer to the combustion chamber at the upper side of the third aggregate container, and a combustion air supply duct that supplies outside air drawn in from the outlet at the lower end to the deodorizing burner at the upper side of the fifth aggregate container.

[0010] Furthermore, the deodorizing device according to claim 2 is characterized by being equipped with a circulation supply means that enables the aggregate cut from the aggregate cutting means to be circulated and supplied to the aggregate supply means.

[0011] Furthermore, the deodorizing device according to claim 3 is characterized in that the particle size of the aggregate supplied to each aggregate container can be changed.

[0012] Furthermore, the deodorizing device according to claim 4 is characterized in that the flow rate of the aggregate flowing downward within each aggregate container can be changed.

[0013] Furthermore, in the deodorization method described in claim 5, after filling each aggregate container with aggregate, the aggregate is supplied from the aggregate supply means and the aggregate is cut out from the aggregate cutting means simultaneously to continuously flow the aggregate filled in each aggregate container downwards, while the exhaust fan is operated to maintain negative pressure inside each aggregate container and the deodorizing burner is ignited and combusted, the recycling dryer is operated in that state to introduce and pass the exhaust gas into the third aggregate container via the upper end of the fourth aggregate container, and at that time, a first heat exchange is performed to preheat the exhaust gas by exchanging heat with the aggregate in a high heat storage state that is flowing inside the third aggregate container, the preheated exhaust gas is supplied to the combustion chamber to burn and decompose the odor components, and the combustion gas produced at that time is used to burn the second aggregate The combustion gas is introduced and passed through the upper end of the container into the first aggregate container, and a second heat exchange is performed in which heat is exchanged with the aggregate that is flowing in the first aggregate container before heat storage is completed, recovering heat from the combustion gas, and the recovered combustion gas is released from the chimney. At the same time, the aggregate that has reached a high heat storage state as a result of the second heat exchange is allowed to flow into the lower aggregate containers, and outside air is drawn in and passed through the negative pressure aggregate container from the outlet at the lower end of the fifth aggregate container, and a third heat exchange is performed in which heat is exchanged with the aggregate that is flowing in the fifth aggregate container and has gone through the first heat exchange, resulting in a low heat storage state which is lower than the high heat storage state, preheating the outside air, and the preheated outside air is supplied to the deodorizing burner and used as combustion air.

[0014] Furthermore, the deodorization method described in claim 6 is characterized in that, instead of the aggregate, concrete rubble is filled and flowed into each of the aggregate containers. [Effects of the Invention]

[0015] According to this invention, aggregates commonly used as materials for asphalt mixtures are used as the heat storage material. Therefore, even if deterioration or damage occurs due to thermal shock during heat exchange, it does not cause any problems, and procurement and replacement are easy, allowing for operation that prioritizes heat exchange efficiency. In addition, the device configuration is relatively simple, which is advantageous in terms of cost and maintenance.

[0016] In addition, since the aggregate that has been made in an absolutely dry state by being used once as a heat storage material can be circulated and supplied and used again as a heat storage material, the waste heat energy consumed to evaporate the contained moisture of the aggregate can be reduced, and more efficient heat exchange becomes possible.

[0017] In addition, since the particle size of the aggregate, which is the heat storage material, can be changed, the heat exchange area of the heat storage material and the pressure loss of the passing gas between the heat storage materials can be freely increased or decreased, and even if the amount of exhaust gas from the recycle dryer fluctuates, efficient heat exchange corresponding thereto becomes possible.

[0018] In addition, since the flow rate of the aggregate, which is the heat storage material, can be changed, the heat capacity of the heat storage material can be freely increased or decreased, and even if the amount of exhaust gas from the recycle dryer fluctuates, efficient heat exchange corresponding thereto becomes possible.

[0019] Furthermore, since concrete waste is used as the heat storage material instead of the aggregate, as in the case of the aggregate, even if deterioration or damage due to heat shock occurs during heat exchange, there is no problem, and operation prioritizing heat exchange efficiency becomes possible. At the same time, as a result of effectively peeling off and removing the mortar component on the surface of the concrete waste accompanying the rapid heating and cooling at that time, it is also possible to recover high-quality recycled aggregate, which is suitable.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic explanatory diagram showing an embodiment of the deodorizing device and the deodorizing method according to the present invention. [Figure 2] It is an enlarged view of the main part of FIG. 1.

Modes for Carrying Out the Invention

[0021] In the deodorizing apparatus and method of the present invention, the deodorizing apparatus is installed on the downstream side of the exhaust duct of a recycling dryer installed in an asphalt plant of an asphalt mixture manufacturing plant. The deodorizing apparatus comprises five hollow aggregate containers connected in series vertically, each having an inlet at the upper end and an outlet at the lower end. The inlets and outlets of adjacent aggregate containers are connected vertically to allow aggregates, exhaust gas, etc. to pass through and communicate with each other.

[0022] Among the above-mentioned aggregate containers connected in series vertically in five stages, above the inlet of the first (uppermost) aggregate container counted from the upper stage side, for example, there is provided aggregate supply means comprising an aggregate input hopper and a supply conveyor having a conveying end facing the aggregate input hopper. On the other hand, below the outlet of the fifth (lowermost) aggregate container, there is provided aggregate cutting means such as a cut-off feeder. Inverters are provided respectively for the drive motors of the supply conveyor and the cut-off feeder to enable the increase and decrease adjustment of the supply speed and the cutting speed of the aggregates.

[0023] Also, a first exhaust duct connected to the recycling dryer is connected to the upper end side of the fourth aggregate container, and a second exhaust duct connected to a chimney via an exhaust fan is connected to the upper end side of the first aggregate container. Further, a combustion chamber having a deodorizing burner is provided on the upper end side of the second aggregate container, an exhaust gas supply duct for supplying exhaust gas (gas to be treated) from the recycling dryer to the combustion chamber is provided on the upper end side of the third aggregate container, and a combustion air supply duct for supplying outside air sucked from the outlet at the lower end of the aggregate container to the deodorizing burner is provided on the upper end side of the fifth aggregate container.

[0024] Preferably, a circulation supply means such as a bucket elevator is provided to enable the circulated supply of the aggregates cut out by the aggregate cutting means to the aggregate supply means. As a result, the aggregates made in an absolutely dry state by being used once as a heat storage material can be circulated and supplied and used again (repeatedly) as a heat storage material, so that the wasted heat energy consumed for evaporating the contained moisture of the aggregates can be reduced, and more efficient heat exchange can be achieved.

[0025] Furthermore, it is preferable to make it possible to change the particle size of the aggregate supplied as a heat storage material in each aggregate container. For example, it is preferable to be able to continuously change (even during operation of the deodorizing device and any number of times) from among crushed stone No. 5 to No. 7 and sand, which are commonly used as materials for asphalt mixtures (new aggregate). This allows the heat exchange area of ​​the heat storage material to be freely increased or decreased within the particle size range of crushed stone No. 5 to sand, and also allows the pressure loss of the passing gas, which fluctuates according to the gap between the heat storage materials, to be freely increased or decreased, enabling efficient heat exchange even if there are fluctuations in the amount of exhaust gas from the recycling dryer.

[0026] Furthermore, it is preferable to make it possible to change the flow rate of the aggregate flowing downward within each aggregate container. For example, the flow rate of the aggregate in each aggregate container can be changed by synchronizing the aggregate supply speed from the aggregate supply means (e.g., supply conveyor) and the aggregate cutting speed from the aggregate cutting means (e.g., cutting feeder). As a result, the heat storage material before and after heat storage can be exchanged at any speed, allowing the heat capacity of the heat storage material to be freely increased or decreased, and similarly, even if there are fluctuations in the amount of exhaust gas from the recycling dryer, efficient heat exchange can be performed accordingly.

[0027] Furthermore, when using the deodorizing device with the above configuration to burn and decompose odor components in exhaust gas from the recycling dryer of an asphalt plant, first, aggregate is supplied and filled into each aggregate container, and then aggregate is supplied from the aggregate supply means and aggregate is cut out from the aggregate cutting means simultaneously, maintaining the state in which aggregate is filled into each aggregate container, and while the aggregate is continuously flowing downwards, the exhaust fan is operated to maintain negative pressure inside each aggregate container, and the deodorizing burner is ignited and combusted.

[0028] Next, the recycling dryer is operated in that state, and the exhaust gas is introduced and passed through the upper end of the fourth aggregate container into the third aggregate container above it. At the same time, a first heat exchange is performed to preheat the exhaust gas by bringing it into direct contact with the aggregate in a high heat storage state that is flowing inside the third aggregate container.

[0029] Next, the preheated exhaust gas is supplied to the combustion chamber via the upper end of the third aggregate container and the exhaust gas supply duct to combust and decompose the odor components in the exhaust gas. The high-temperature combustion gas generated at that time is introduced and passed through the upper end of the second aggregate container into the first aggregate container above it, and a second heat exchange is performed to recover heat from the combustion gas by bringing it into direct contact with the aggregate that is flowing inside the first aggregate container before heat storage (immediately after being supplied by the aggregate supply means) and before heat storage.

[0030] The recovered combustion gas is then released into the atmosphere through the upper end of the first aggregate container and the second exhaust duct, and out the chimney at the end. Meanwhile, the aggregate, which has reached a high heat storage state due to the second heat exchange, is allowed to flow into the lower aggregate containers and used for the first heat exchange described above. In addition, outside air is drawn in and passed through the negative-pressure aggregate container from the outlet at the lower end of the fifth aggregate container. At this time, a third heat exchange is performed to preheat the outside air by bringing it into direct contact with the aggregate, which is flowing inside the fifth aggregate container and has gone through the first heat exchange, resulting in a low heat storage state that is lower than the high heat storage state. The preheated outside air is then supplied to the deodorizing burner through the upper end of the fifth aggregate container and the combustion air supply duct and used as combustion air.

[0031] Thus, with the above-described deodorizing device and deodorizing method, aggregates commonly used as materials for asphalt mixtures in asphalt plants, such as No. 5 to No. 7 crushed stone and sand, are used as heat storage materials. Therefore, even if deterioration or damage occurs due to thermal shock during heat exchange, there is no problem, and procurement and replacement are easy. As a result, operation prioritizing heat exchange efficiency, such as repeated operation involving rapid heating and cooling at short intervals, is possible, leading to improved fuel efficiency and CO2 reduction. This makes it particularly suitable as a deodorizing device and deodorizing method for asphalt plants that are forced to operate intermittently.

[0032] Furthermore, the outside air supplied as combustion air for the deodorizing burner can be preheated with the heat-storage aggregate, leading to further improvements in fuel efficiency and CO2 reduction. In addition, since the aggregate used as heat storage material can be recovered in a completely dry state, it can be used directly as a material for asphalt mixtures in asphalt plants, resulting in energy savings and CO2 reductions at the plant side as well. Moreover, the configuration of the deodorizing device is relatively simple, consisting of multiple aggregate containers arranged vertically, making it advantageous in terms of cost and maintenance, and relatively easy to adopt.

[0033] Furthermore, if, for example, industrial waste concrete rubble crushed to a predetermined particle size is used as a heat storage material instead of the aggregate, there will be no problems even if deterioration or damage occurs due to thermal shock during heat exchange, just as with the aggregate, and procurement and replacement will be easy. As a result, operation prioritizing heat exchange efficiency will be possible, and the mortar components on the surface can be effectively peeled off due to the rapid heating and cooling, as well as the friction between the flowing concrete rubble, resulting in the recovery of high-quality (low amount of adhering mortar) recycled aggregate. This method can be particularly suitable for this application. [Examples]

[0034] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0035] In the figure, 1 is a deodorizing device according to the present invention, which is installed downstream of the first exhaust duct 4a of a recycling dryer 3 installed in an asphalt plant 2 of an asphalt mixture manufacturing plant. The recycling dryer 3 has a substantially cylindrical drum body 5 that is rotatably tilted and supported, and is equipped with a burner 7 and a waste material input chute 8 at one end (upstream end) of the drum body 6, and a surge bin 9 at the other end (downstream end) for temporarily storing heat-treated waste material (recycled material). The surge bin 9 and the deodorizing device 1 are connected by a first exhaust duct 4a equipped with an exhaust fan 10 in the middle.

[0036] The deodorizing device 1 consists of five hollow aggregate containers 13a to 13e arranged vertically in series, each having an input port 11 for loading aggregate at its upper end and an output port 12 for discharging aggregate at its lower end. The input ports 11 and output ports 12 of adjacent aggregate containers 13a to 13e are connected to each other, allowing aggregate and exhaust gas to pass through.

[0037] The aggregate containers 13a to 13e can preferably consist of, for example, a roughly cylindrical main body 14, a roughly disc-shaped top plate 15 covering the upper part of the main body 14, and a roughly funnel-shaped discharge section 16 connected to the lower end of the main body 14, with the input port 11 located approximately in the center of the top plate 15 and the discharge port 12 located at the lower end of the discharge section 16. With this configuration, as will be described later, when aggregate A is supplied and filled into each aggregate container 13a to 13e, the aggregate A can be stably stacked up to near the upper end of the center of the main body 14 of each aggregate container 13a to 13e while maintaining its angle of repose, while gap spaces 17a to 17e that serve as passages for exhaust gas, combustion gas, etc., can be formed around the outer periphery of the stacked aggregate A (upper corners of the main body 14 of the aggregate container). In this case, the heat-resistant, wear-resistant, and high-strength grids and louvers required in conventional heat exchangers to hold the heat storage material are unnecessary (in this embodiment, the aggregate A, which is the heat storage material, is stably stacked in the aggregate containers 13a to 13e while maintaining the angle of repose), which also contributes to lowering the cost of the equipment.

[0038] Of the five aggregate containers 13a to 13e arranged vertically in a series, the first (uppermost) aggregate container 13a, counting from the top, is equipped with an aggregate supply means 20 consisting of an aggregate input hopper 18 and a supply conveyor 19 with its transport end facing the aggregate input hopper 18 above its input port 11, while the fifth (lowest) aggregate container 13e is equipped with an aggregate cutting means 22, such as a cutting feeder 21, below its discharge port 12. The drive motors (not shown) of the supply conveyor 19 and the cutting feeder 21 are each equipped with inverters (not shown), allowing for adjustment of the supply speed and cutting speed of aggregate A.

[0039] Furthermore, as described above, a first exhaust duct 4a connected to the recycling dryer 3 is connected to the upper side of the fourth aggregate container 13d, and a second exhaust duct 4b connected to the chimney 24 via an exhaust fan 23 is connected to the upper side of the first aggregate container 13a. In addition, a combustion chamber 26 having a deodorizing burner 25 is connected to the upper side of the second aggregate container 13b, an exhaust gas supply duct 27 that supplies exhaust gas (gas to be treated) from the recycling dryer 3 to the combustion chamber 26 is connected to the upper side of the third aggregate container 13c, and a combustion air supply duct 28 that supplies outside air drawn in from the outlet 12 at the lower end of the aggregate container 13e to the deodorizing burner 25 is connected to the upper side of the fifth aggregate container 13e.

[0040] In the figure, 29 is a circulation supply means, such as a bucket elevator, that allows a portion or all of the aggregate A cut from the cutting feeder 21 of the aggregate cutting means 22, which was used as a heat storage material in the deodorization device 1, to be circulated and supplied to the supply conveyor 19 of the aggregate supply means 20. By circulating and supplying the aggregate A, which has been used once as a heat storage material in the deodorization device 1 (after a thermal history) and is in an extremely dry state, so that it can be used again (repeatedly), the wasted thermal energy spent to evaporate the moisture contained in the aggregate A is reduced, and the heat exchange efficiency is improved.

[0041] In the figure, 30 is a kiln static pressure sensor that detects the static pressure inside the kiln body 5 of the recycle dryer 3, and 31 is a static pressure controller. The static pressure controller 31 adjusts and controls the exhaust volume of the exhaust fan 23 interposed in the middle of the second exhaust duct 4b based on the value detected by the kiln static pressure sensor 30, and maintains the inside of the kiln body 5 at a predetermined negative pressure slightly lower than atmospheric pressure, for example, in the range of -5 mmAq to -20 mmAq. This suppresses the outflow of combustion gas from gaps at both ends of the kiln body 5 even when the combustion volume of the burner 7 is increased or decreased, and also suppresses the intrusion of outside air into the kiln body 5, which would lead to a deterioration of heating efficiency.

[0042] Furthermore, the upper ends of the first aggregate container 13a and the fourth aggregate container 13d, located between the recycle dryer 3 and the exhaust fan 23 (in the path), are equipped with internal static pressure sensors 32a and 32b, respectively, which can detect the differential pressure between them. When the amount of exhaust gas from the recycle dryer 3 (the amount of combustion from the burner 7) increases or decreases, the pressure loss of the gas passing between the aggregate A (heat storage material) in each aggregate container 13a to 13c also fluctuates accordingly, and this can be detected by the differential pressure between the internal static pressure sensors 32a and 32b. In addition, the second exhaust duct 4b is equipped with a gas temperature sensor 33 for detecting the temperature of the combustion gas discharged from the deodorizing device 1.

[0043] Then, when using the deodorizing device 1 with the above configuration to combust and decompose odor components in the exhaust gas from the recycling dryer 3 of the asphalt plant 2 (note that the aggregate temperature values ​​and exhaust gas temperature values ​​described in this embodiment are reference values ​​in the simulation and do not necessarily mean that the temperature will be controlled to these values), first, aggregate A is supplied and filled into each of the aggregate containers 13a to 13e. At this time, a certain amount of aggregate A is also stored in the aggregate input hopper 18 above the first aggregate container 13a. As a result, the aggregate A in the aggregate input hopper 18 acts as a material seal, and as will be described later, when the exhaust fan 23 of the second exhaust duct 4b is operated, it becomes possible to maintain negative pressure inside each of the aggregate containers 13a to 13e, along with the inside of the kiln body 5 of the recycling dryer 3.

[0044] Next, aggregate is supplied from the aggregate supply means 20, aggregate is cut from the aggregate cutting means 22, and circulated through the circulation supply means 29 is performed simultaneously, and while maintaining the state in which aggregate A is filled in each aggregate container 13a to 13e, the aggregate A is continuously flowed downward, and the exhaust fan 23 in the middle of the second exhaust duct 4b is operated to maintain negative pressure inside each aggregate container 13a to 13e, while the deodorizing burner 25 is ignited and combusted.

[0045] Then, the recycling dryer 3 is operated in that state to heat-treat the waste material, and during that time, the static pressure value inside the kiln body 5 detected by the kiln static pressure sensor 30 is continuously received by the static pressure controller 31. The static pressure controller 31 adjusts and controls the exhaust volume of the exhaust fan 23 of the second exhaust duct 4b based on the received static pressure value inside the kiln body 5, and maintains the inside of the kiln body 5 at a predetermined negative pressure value slightly lower than atmospheric pressure, as described above. At this time, the inside of each aggregate container 13a to 13d of the deodorizing device 1, located between the recycling dryer 3 and the exhaust fan 23, is also maintained at a negative pressure value.

[0046] On the other hand, the exhaust gas (approximately 180°C) generated by the heating treatment of waste materials in the recycling dryer 3 is introduced and passed through the first exhaust duct 4a and the gap space 17d at the upper end of the fourth aggregate container 13d (the gap space 17d formed on the outer periphery of the aggregate A, which is stacked while maintaining the angle of repose up to near the upper end of the center of the main body portion 14 of the aggregate container 13d) into the upper third aggregate container 13c. At this time, the exhaust gas is brought into direct contact with the aggregate A, which is in a high heat storage state (approximately 700°C) flowing downwards within the third aggregate container 13c, thereby performing a first heat exchange (HE1) to preheat the exhaust gas.

[0047] Next, the preheated exhaust gas (approximately 600°C) is supplied into the combustion chamber 26 via the gap space 17c at the upper end of the third aggregate container 13c and the exhaust gas supply duct 27, and the odor components in the exhaust gas are combusted and decomposed by the hot air from the deodorizing burner 25. The high-temperature combustion gas (approximately 750°C) generated at this time is introduced and passed through the gap space 17b at the upper end of the second aggregate container 13b into the first aggregate container 13a above it, and heat is exchanged by bringing the aggregate A, which is flowing downwards in the first aggregate container 13a and is at room temperature immediately after being supplied from the aggregate supply means 20, into direct contact with the aggregate A before heat storage (room temperature) is released, thereby recovering heat from the combustion gas in a second heat exchange (HE2).

[0048] The recovered combustion gas (approximately 80°C) is then released into the atmosphere through the gap space 17a at the upper end of the first aggregate container 13a and the second exhaust duct 4b, and then released into the atmosphere from the chimney 24 at the end. Meanwhile, the aggregate A, which has reached a high heat storage state (approximately 700°C) due to the second heat exchange (HE2), is allowed to flow to the lower aggregate containers and used for the first heat exchange (HE1) and the like.

[0049] Furthermore, outside air (room temperature) is drawn in and passed through the negative-pressure aggregate container 13e from the discharge port 12 at the lower end of the fifth aggregate container 13e, and a third heat exchange (HE3) is performed to preheat the outside air by bringing it into direct contact with the aggregate A, which is flowing downwards through the fifth aggregate container 13e and has passed through the first heat exchange (HE1) to a low heat storage state (approximately 300°C), which is lower than the high heat storage state. The preheated outside air (approximately 250°C) is then supplied to the deodorizing burner 25 via the gap space 17e at the upper end of the fifth aggregate container 13e and the combustion air supply duct 28, and used as combustion air. Furthermore, the inside of the aggregate container 13e is maintained under negative pressure not only by the exhaust fan 23 but also by the suction of combustion air due to the combustion of the deodorizing burner 25. As a result, outside air is drawn in through the outlet 12 at the lower end of the aggregate container 13e, as described above.

[0050] At this time, during the first heat exchange (HE1), some of the odor components (asphalt mist) contained in the exhaust gas (gas to be treated) from the recycling dryer 3 temporarily adhere to the surface of aggregate A (aggregate A is contaminated). However, during the third heat exchange (HE3), the odor components are detached again from the surface of aggregate A (aggregate A is cleaned), and these odor components are supplied to the deodorizing burner 25 along with the preheated outside air and are combusted and decomposed.

[0051] Furthermore, the aggregate A (approximately 50°C), which is purified after passing through the third heat exchange (HE3) and discharged from the discharge port 12 at the lower end of the fifth aggregate container 13e, falls onto the cutting feeder 21 of the lower aggregate cutting means 22, where it is sequentially cut out. Then, some or all of the cut aggregate A is circulated and supplied to the supply conveyor 19 of the aggregate supply means 20 via the circulation supply means 29, and is again supplied and circulated into each of the aggregate containers 13a to 13e for reuse as a heat storage material.

[0052] Here, the aggregate A, which is circulated and supplied via the circulation supply means 29, is in an extremely dry state after being used once as a heat storage material (having gone through a thermal history of about 700°C). By using it again (repeatedly) as a heat storage material, it is possible to reduce the wasted thermal energy spent to evaporate the moisture contained in the aggregate A, and an improvement in heat exchange efficiency can be expected.

[0053] On the other hand, aggregate A that is not circulated by the circulation supply means 29 is directly supplied to the virgin dryer (not shown) of the asphalt plant 2 and heated and dried to a predetermined temperature (approximately 160°C), and is effectively used as a material for asphalt mixture. At this time, as with the above, aggregate A is in a completely dry state because it has been used as a heat storage material in the deodorizing device 1, and is also heated to a temperature of approximately 50°C, so energy saving and CO2 reduction effects can be expected on the plant side.

[0054] Thus, according to the deodorizing device and deodorizing method of the present invention, aggregates that are normally used as materials for asphalt mixtures are used as the heat storage material. Therefore, even if deterioration or damage occurs due to thermal shock during heat exchange, there is no problem, and operation prioritizing heat exchange efficiency becomes possible, leading to improved fuel efficiency and the expected effect of reducing CO2 emissions.

[0055] Furthermore, while conventional deodorization devices discharge exhaust gas at approximately 180°C from the recycling dryer and release it into the atmosphere at a relatively high temperature of approximately 300-400°C after deodorization treatment, the deodorization device and method of the present invention can reduce the temperature to approximately 80°C, which is considerably lower than the temperature at which it was discharged from the recycling dryer (heat recovery), thus achieving both economic efficiency and environmental friendliness.

[0056] Furthermore, the device configuration does not require complex switching mechanisms for exchanging heat-dissipating and heat-receiving gases, as is the case with RTOs, making it advantageous in terms of cost and maintenance, and thus relatively easy to adopt.

[0057] Furthermore, it is preferable to make it possible to change the particle size of aggregate A supplied as a heat storage material in each of the aggregate containers 13a to 13e. For example, it is preferable to be able to continuously change (even during operation of the deodorizing device 1, and any number of times) from among crushed stone No. 5 to No. 7 and sand, which are commonly used as materials (new aggregates) for asphalt mixtures. This allows the heat exchange area of ​​the heat storage material to be freely increased or decreased within the particle size range of crushed stone No. 5 to sand, and also allows the pressure loss of the passing gas, which fluctuates according to the gap between the heat storage materials, to be freely increased or decreased. For example, even if the amount of waste material processed in the recycling dryer 3 fluctuates, or if there are fluctuations in the amount of exhaust gas from the recycling dryer 3 (combustion amount of burner 7) when the recycling dryer 3 is started up or shut down, efficient heat exchange can be performed accordingly.

[0058] More specifically, the smaller the particle size of aggregate A, the greater the effective heat exchange area as a heat storage material, and the narrower the gaps between aggregate A particles, increasing the pressure loss of the passing gas. On the other hand, the larger the particle size of aggregate A, the smaller the heat exchange area, and the wider the gaps between aggregate A particles, decreasing the pressure loss of the passing gas.

[0059] Therefore, for example, if the amount of exhaust gas from the recycling dryer 3 decreases and the amount of heat in the exhaust gas decreases, changing the aggregate A to one with a smaller particle size (for example, if No. 5 crushed stone was used, to No. 6 or 7 crushed stone, or sand) will increase the heat exchange area and improve the heat exchange efficiency, thereby suppressing the decrease in the amount of heat stored in the deodorizer 1. At this time, although the pressure loss of the passing gas will also increase, this will be offset by the decrease in the amount of exhaust gas, so no adverse effects such as overloading the exhaust fan 23 will occur.

[0060] On the other hand, if the amount of exhaust gas from the recycling dryer 3 increases and the pressure loss of the passing gas increases, the pressure loss can be reduced by changing the particle size of aggregate A to a larger size (for example, if No. 7 crushed stone was being used, to No. 5 or 6 crushed stone). As a result, overload of the exhaust fan 23 is prevented, and stable operation of the deodorizing device 1 is possible. In this case, although the heat exchange area also decreases, this is offset by the increase in the amount of exhaust gas (heat content of the exhaust gas), so no adverse effects such as a decrease in heat storage capacity occur.

[0061] Furthermore, in detecting the increase or decrease in pressure loss of the passing gas due to the increase or decrease in the amount of exhaust gas from the recycling dryer 3, this embodiment uses the difference in static pressure values ​​(differential pressure value) between the static pressure sensors 32a and 32b located inside the first aggregate container 13a and the fourth aggregate container 13d, and employs feedback control to change the particle size of aggregate A based on the differential pressure value. When the differential pressure value falls outside a predetermined range (set differential pressure range: for example, around 100 to 200 mmAq), it is preferable to change the particle size of the supplied aggregate A. For example, if the value falls below the set differential pressure range, it is preferable to determine that the pressure loss has decreased and change to a smaller aggregate particle size, and if the value exceeds the set differential pressure range, it is preferable to determine that the pressure loss has increased and change to a larger aggregate particle size.

[0062] Furthermore, as aggregate containers to which the in-container static pressure sensors 32a and 32b for detecting the differential pressure value are to be installed, for example, any two can be arbitrarily selected from the first aggregate container 13a to the fourth aggregate container 13d. However, the fifth aggregate container 13e is configured to draw in outside air from the lower end opening 12 and to lead the drawn-in outside air to the deodorizing burner 25 via the combustion air supply duct 28, which may affect the differential pressure value, so it is preferable to exclude it from the installation of the in-container static pressure sensors.

[0063] Furthermore, when changing the particle size of aggregate A, it is not always necessary to change the particle size of all aggregates; it is also acceptable to change only a portion of them. In this case, it is possible to adjust to an intermediate aggregate particle size (for example, by using half No. 5 crushed stone and half No. 6 crushed stone, it is possible to adjust to an aggregate particle size similar to No. 5.5 crushed stone), allowing for finer particle size adjustments that are in line with the amount of exhaust gas.

[0064] Furthermore, when aggregate A, which was used as a heat storage material, is used as a material for the asphalt mixture in asphalt plant 2, it is heated and dried in a virgin dryer and then sieved by particle size using a vibrating screen (not shown) mounted on the plant body (not shown) before use. Therefore, even if it is a mixture of No. 5 crushed stone and No. 6 crushed stone as described above, there is no particular problem.

[0065] Furthermore, it is preferable to make it possible to change the flow rate of the aggregate A flowing downward within each of the aggregate containers 13a to 13e. For example, the flow rate of the aggregate A within each of the aggregate containers 13a to 13e can be changed by synchronizing the aggregate supply speed from the aggregate supply means 20 (e.g., supply conveyor 19) and the aggregate cutting speed from the aggregate cutting means 22 (e.g., cutting feeder 21). As a result, the heat storage material (aggregate A) before and after heat storage can be exchanged at any speed, allowing the heat capacity of the heat storage material to be freely increased or decreased. For example, even if the amount of waste material processed by the recycling dryer 3 fluctuates, or if there are fluctuations in the amount of exhaust gas from the recycling dryer 3 (combustion amount of burner 7) during startup or shutdown of the recycling dryer 3, efficient heat exchange can be performed accordingly.

[0066] More specifically, the faster the flow rate of aggregate A, the greater its effective heat capacity (specific heat × mass) as a heat storage material. Conversely, the slower the flow rate, the less heat capacity it has. For example, if the amount of exhaust gas from the recycling dryer 3 decreases, the flow rate of aggregate A should be reduced. Conversely, if the amount of exhaust gas from the recycling dryer 3 increases, the flow rate of aggregate A should be increased. This allows for a good balance between the heat capacity of the gas being treated (the heat radiating side) and the heat capacity of the heat storage material (the heat receiving side), resulting in more efficient heat exchange. The maximum heat exchange efficiency is achieved when the ratio of the heat capacity of the gas being treated to the heat storage material (the heat receiving side) is approximately 1:1.

[0067] In particular, when the amount of exhaust gas (heat content of exhaust gas) from the recycling dryer 3 exceeds a certain amount, the temperature of aggregate A, which is the heat storage material in the deodorizing device 1, remains at a high temperature, and in some cases, saturation (a saturated state in which heat exchange with the exhaust gas does not proceed) may occur. However, even in that case, as described above, by increasing the flow rate of aggregate A and quickly replacing it with low-temperature aggregate A, the heat capacity of the heat storage material can be effectively increased, making it possible to maintain highly efficient heat exchange.

[0068] Furthermore, in detecting the increase or decrease in the amount of heat stored (heat storage temperature) of the heat storage material in response to an increase or decrease in the amount of exhaust gas from the recycling dryer 3, this embodiment employs feedback control that detects the change in the combustion gas temperature value at the gas temperature sensor 33 provided in the second exhaust duct 4b and changes the flow rate of the aggregate A based on the gas temperature value. When the gas temperature value falls outside a predetermined range (set gas temperature range: for example, around 70 to 90°C), it is preferable to change the flow rate of the supplied aggregate A. For example, if the temperature falls below the set gas temperature range, it is preferable to slow down the flow rate of aggregate A as it is determined that the amount of heat stored (heat storage temperature) of the heat storage material has decreased (fallen) due to a decrease in the amount of exhaust gas, etc. Conversely, if the temperature rises above the set gas temperature range, it is preferable to speed up the flow rate of aggregate A as it is determined that the amount of heat stored (heat storage temperature) of the heat storage material has increased (rise) due to an increase in the amount of exhaust gas, etc. Alternatively, instead of the gas temperature sensor 33, an aggregate temperature sensor may be installed in, for example, the aggregate container 13b, to directly detect the temperature of the heat storage material.

[0069] Furthermore, by simultaneously (combining) adjusting the particle size and flow rate of the supplied aggregate A, more optimal adjustments can be achieved. For example, when the amount of exhaust gas from the recycling dryer 3 increases, increasing the particle size of aggregate A and increasing the flow rate allows for adjustment to a heat capacity commensurate with the amount of exhaust gas while suppressing the increase in pressure loss. Conversely, when the amount of exhaust gas decreases, decreasing the particle size of aggregate A and decreasing the flow rate allows for adjustment to a heat capacity commensurate with the amount of exhaust gas while increasing the heat exchange area and improving heat exchange efficiency. Thus, more precise adjustments are possible.

[0070] Furthermore, in this embodiment, the outside air preheated through the third heat exchange (HE3) is supplied to the deodorizing burner 25. However, it may also be supplied to, for example, the burner 7 of the recycling dryer 3 on the plant main body side, or to the burner (not shown) of the virgin dryer (not shown), and used as combustion air in each of these burners. In that case, further improvements in fuel efficiency and reductions in CO2 emissions can be expected.

[0071] Furthermore, as a heat storage material used in the deodorizing device 1, concrete rubble crushed to a predetermined particle size can be suitably used instead of aggregate A used in the asphalt plant 2. Concrete rubble, being industrial waste, does not cause any problems even if it deteriorates or is damaged due to thermal shock during heat exchange, just like aggregate A, and is easy to procure and replace. As a result, operation prioritizing heat exchange efficiency is possible, and the mortar components on the surface can be effectively peeled off due to the rapid heating and cooling at that time, as well as the friction between the concrete rubble as it flows down each aggregate container 13a to 13e. As a result, it can be recovered as high-quality (low amount of attached mortar) recycled aggregate, making it particularly suitable for application. [Industrial applicability]

[0072] This invention can be widely used as a deodorizing system for odor-containing gases generated in asphalt plants. [Explanation of symbols]

[0073] 1…Deodorizing equipment 2…Asphalt plant 3…Recycle dryer 4a…First exhaust duct 4b...Second exhaust duct 11...Inlet (aggregate container) 12…Discharge port (aggregate container) 13a~13e…Aggregate container 20… means for supplying aggregate 22… means for cutting aggregate 23…Exhaust fan 24…Chimney 25... Deodorizing burner 26... Combustion chamber 27... Exhaust gas supply duct 28... Combustion air supply duct 29...Circulation supply means 31...Static pressure controller 32a, 32b... Static pressure sensor inside the container; 33... Gas temperature sensor A... Aggregate (heat storage material)

Claims

1. A deodorizing device for combustion and decomposition of odor components in exhaust gas from a recycling dryer of an asphalt plant, comprising five hollow aggregate containers arranged vertically in series, each having an inlet at the top and an outlet at the bottom, with the inlets and outlets of adjacent aggregate containers connected to each other, with an aggregate supply means provided above the inlet of the first aggregate container counting from the top, and an aggregate cutting means provided below the outlet of the fifth aggregate container, and the upper side of the fourth aggregate container having the recycling A deodorizing device characterized by having a first exhaust duct connected to a dryer, a second exhaust duct connected to a chimney via an exhaust fan at the upper side of the first aggregate container, a combustion chamber having a deodorizing burner at the upper side of the second aggregate container, an exhaust gas supply duct for supplying exhaust gas from the recycling dryer to the combustion chamber at the upper side of the third aggregate container, and a combustion air supply duct for supplying outside air drawn in from the outlet at the lower end to the deodorizing burner at the upper side of the fifth aggregate container.

2. The deodorizing device according to claim 1, further comprising a circulation supply means that enables the circulation supply of aggregate cut from the aggregate cutting means to the aggregate supply means.

3. The deodorizing device according to claim 1, characterized in that the particle size of the aggregate supplied to each of the aggregate containers can be changed.

4. The deodorizing device according to claim 1, characterized in that the flow rate of the aggregate flowing downward in each of the aggregate containers can be changed.

5. A method for operating the deodorizing apparatus according to any one of claims 1 to 4, wherein after filling each aggregate container with aggregate, the aggregate is supplied from the aggregate supply means and the aggregate is cut out from the aggregate cutting means simultaneously to cause the aggregate filled in each aggregate container to flow continuously downward, the exhaust fan is operated to maintain negative pressure inside each aggregate container, and the deodorizing burner is ignited and combusted, the recycling dryer is operated in that state to introduce and pass the exhaust gas into the third aggregate container via the upper end of the fourth aggregate container, a first heat exchange is performed in which the exhaust gas is preheated by exchanging heat with the aggregate in a high heat storage state that is flowing inside the third aggregate container, the preheated exhaust gas is supplied to the combustion chamber to burn and decompose odor components, and the combustion gas produced at that time is A deodorization method characterized by introducing and passing a combustion gas into the first aggregate container via the upper end of the second aggregate container, performing a second heat exchange in which heat is exchanged with the aggregate flowing in the first aggregate container before heat storage, recovering heat from the combustion gas, and releasing the heat-recovered combustion gas from the chimney, while the aggregate that has reached a high heat storage state as a result of the second heat exchange is allowed to flow into the lower aggregate containers, and outside air is drawn in and passed through the negative pressure aggregate container from the discharge port at the lower end of the fifth aggregate container, performing a third heat exchange in which heat is exchanged with the aggregate flowing in the fifth aggregate container and which has gone through the first heat exchange and is in a low heat storage state at a lower temperature than the high heat storage state, preheating the outside air, and supplying the preheated outside air to the deodorizing burner to be used as combustion air.

6. A deodorizing method according to claim 5, characterized in that concrete rubble is filled and circulated in each of the aggregate containers instead of the aggregate.

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