Method for demolishing exhaust duct

Abstract

To provide a method for demolishing an exhaust duct capable of safely and simply demolishing an exhaust duct to an inner surface of which harmful substances adhere.SOLUTION: A method for demolishing an exhaust duct 11, which has harmful substances adhering to its inner surface and is composed of a plurality of connected duct members 15, repeatedly performs duct member blockage processing of: disconnecting the duct members 15 from each other while exhausting air inside a duct from a downstream end side of the exhaust duct 11; inserting two partition plates 23, 24 between the duct members 15; blocking a downstream opening 25 of the upstream duct member 15 with one of the inserted partition plates 23; and blocking an upstream opening 26 of the downstream duct member 15 with the other inserted partition plate 24.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for dismantling an exhaust duct installed in a facility that handles hazardous substances. [Background technology]

[0002] PCBs (polychlorinated biphenyls), a hazardous substance, are chemically extremely stable and non-flammable. They have excellent heat resistance and insulating properties, and have therefore been widely used as insulating oil in transformers and capacitors. However, it has become clear that PCBs have an impact on the biological environment, and their use is now prohibited. Therefore, transformers, capacitors, rectifiers, fluorescent light ballasts, and other devices that contain PCBs and have been used until now are treated as PCB waste requiring special treatment and are being detoxified at PCB waste treatment facilities.

[0003] Furthermore, with the progress of PCB waste disposal, there has been a need in recent years to dismantle and remove PCB waste disposal facilities. When dismantling a PCB waste treatment facility, one method is to cover the area around the equipment with a greenhouse to create an airtight space and then create a negative pressure in this airtight space compared to the outside air pressure before carrying out the removal work in order to prevent contamination from spreading to the surrounding area (see, for example, Patent Document 1). Another method is to use a glove box or glove bag in which workers work through a panel wearing gloves in a sealed space to prevent PCBs from leaking outside. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-164687 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the exhaust system, including the ducts that are the main equipment for preventing PCB leakage installed in PCB waste treatment facilities, must be dismantled and removed last. This dismantling and removal is performed after the exhaust system's exhaust operation has stopped, so separate measures to prevent PCB leakage must be taken. Furthermore, depending on the environment in which the exhaust ducts of this exhaust system are installed, it can be difficult to install the greenhouses mentioned above, and even if they can be installed, the workability during dismantling is significantly reduced. Furthermore, because the exhaust ducts are usually installed over a wide area, the glove boxes and glove bags mentioned above cannot be used.

[0006] An object of the present invention is to provide a method for dismantling an exhaust duct that can safely and easily dismantle an exhaust duct having harmful substances such as PCBs adhering to its inner surface. [Means for solving the problem]

[0007] The inventors conducted various studies on methods for dismantling exhaust ducts with harmful substances adhering to their inner surfaces, and as a result discovered that the above problem could be solved by dismantling the exhaust duct by repeatedly disconnecting the duct members that make up the exhaust duct while exhausting the air inside the exhaust duct, inserting partition plates between the duct members, and blocking the openings of each duct member with the partition plates, thereby completing the present invention.

[0008] The gist of the present invention is as follows. [1] A method for dismantling an exhaust duct that has harmful substances adhering to its inner surface and is made up of multiple connected duct members, comprising: A method for dismantling an exhaust duct, characterized by repeatedly performing a duct member closing process in which the duct members are disconnected from each other while exhausting air from the downstream end of the exhaust duct, two partition plates are inserted between the duct members, and one of the inserted partition plates is used to close the downstream opening of the upstream duct member A, while the other inserted partition plate is used to close the upstream opening of the downstream duct member B.

[0009] [2] The method for dismantling an exhaust duct according to [1], characterized in that the duct member blocking process is carried out sequentially from the upstream side of the exhaust duct.

[0010] [3] A method for dismantling an exhaust duct according to [1] or [2], characterized in that before the duct member closing process, the upstream end of the most upstream duct member A to be subjected to the duct member closing process is closed with a partition plate.

[0011] [4] A method for dismantling an exhaust duct according to any one of [1] to [3], characterized in that after the duct member closing process, the closed duct member with both the upstream end and the downstream end closed is carried out.

[0012] [5] A method for dismantling an exhaust duct according to any one of [1] to [4], characterized in that the duct member blocking treatment is performed on duct members placed in a clean space that is substantially free of harmful substances.

[0013] [6] A method for dismantling an exhaust duct according to any one of [1] to [5], characterized in that, before the duct member blocking treatment, a duct member with contaminated internal and external surfaces that is connected upstream or downstream of the duct member to be subjected to the duct member blocking treatment and is placed in a space contaminated with harmful substances is disconnected and the duct member with contaminated internal and external surfaces is removed.

[0014] [7] A method for dismantling an exhaust duct described in any one of [1] to [6], characterized in that the duct member blocking process is carried out while exhausting air from the exhaust duct and supplying air into the downstream duct member B that is being disconnected or has been disconnected.

[0015] [8] A method for dismantling an exhaust duct as described in [7], characterized in that air is supplied into the duct member through a hole provided in the side wall of the downstream duct member B.

[0016] [9] A method for dismantling an exhaust duct as described in [7], characterized in that air is supplied into the duct member through a hole provided in the partition plate of the downstream duct member B.

[0017]

[10] The method for dismantling an exhaust duct according to any one of [1] to [9], wherein the partition plate is made of the same material as the duct member.

[0018]

[11] A method for dismantling an exhaust duct according to any one of [1] to

[10] , characterized in that the harmful substance is PCB and the concentration of PCB adhering to the inner surface of the exhaust duct is at a low-concentration contamination level that can be treated in a low-concentration detoxification treatment facility. [Effects of the Invention]

[0019] According to the exhaust duct dismantling method of the present invention, exhaust ducts having harmful substances adhering to their inner surfaces can be safely and easily dismantled. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a flow diagram of an embodiment of a method for dismantling an exhaust duct of the present invention. [Figure 2] FIG. 10 is an explanatory diagram of an exhaust duct to which the exhaust duct disassembly method is applied. [Figure 3] 10 is an explanatory diagram of a duct member closing process in the exhaust duct dismantling method. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] The method for dismantling an exhaust duct of the present invention is a method for dismantling an exhaust duct having harmful substances adhering to its inner surface and composed of multiple connected duct members, and is characterized in that while exhausting the air inside the duct from the downstream end side of the exhaust duct, the duct members are disconnected from each other, two partition plates are inserted between the duct members, and a duct member closing process is repeatedly performed in which one of the inserted partition plates is used to close the downstream opening of the upstream duct member A and the other inserted partition plate is used to close the upstream opening of the downstream duct member B. Note that exhaust ducts are usually equipped with an air exhaust device that exhausts air inside the exhaust duct and are configured to generate a predetermined air flow, so upstream and downstream in the present invention are defined along this air flow.

[0022] The method for dismantling an exhaust duct of the present invention is a novel technique that involves repeatedly performing the above-described duct member blocking process, i.e., inserting partition plates between disconnected duct members and blocking the openings of each duct member with the partition plates while exhausting the air inside the exhaust duct. This allows for safe and easy dismantling of exhaust ducts with hazardous substances adhering to their inner surfaces. Specifically, the method prevents hazardous substances contained in the air inside the exhaust duct from leaking to the outside and protects dismantling workers from exposure, while easily dismantling the exhaust duct without requiring large-scale equipment.

[0023] The duct member blocking treatment of the present invention is performed repeatedly as described above, and is preferably performed sequentially from the upstream side of the exhaust duct. However, depending on the configuration of the exhaust duct and the installation conditions of the exhaust duct, it may also be performed from an intermediate position. In some cases, two to four or so duct members may be removed as a single unit. After removal, partition plates may be installed on both sides of each duct member. Note that even when such a mode of removing multiple duct members as a single unit is included, as long as it is understood that the treatment is performed from the upstream side as a whole, it is included in the treatment mode of the present invention that is performed sequentially from the upstream side of the exhaust duct.

[0024] Furthermore, when performing duct member blockage treatment, exhausting the air inside the duct from the downstream end of the exhaust duct means sucking in air from downstream of the most downstream duct member B that will undergo duct member blockage treatment. An existing air exhaust device attached to the exhaust duct can be used as the device to exhaust the air inside the duct, but since duct member blockage treatment does not require powerful exhaust capacity, a portable air exhaust device can be used.

[0025] Furthermore, the duct member closing process may be performed while exhausting the air from the exhaust duct and supplying air into the downstream duct member B that has been disconnected or released. Air may be supplied into the duct member through, for example, a hole provided in the side wall of the downstream duct member B, or through a hole provided in the partition plate of the downstream duct member B.

[0026] Examples of harmful substances adhering to the inner surface of an exhaust duct include PCBs, dioxins, cadmium compounds, cyanide compounds, mercury compounds, lead compounds, etc. As mentioned above, as the treatment of PCB waste progresses, it becomes necessary to dismantle and remove PCB waste treatment facilities. Therefore, the present invention is particularly useful for exhaust ducts with PCBs adhering to their inner surface. For example, the concentration of PCBs adhering to the inner surface of an exhaust duct may be reduced to a low-concentration contamination level (0.1 μg / 100 cm ) that can be treated in a low-concentration detoxification treatment facility. 2 Super~1000μg / 100cm 2 (see below) is preferred.

[0027] The exhaust duct that is the subject of dismantling in this invention is made up of multiple duct components connected by connecting means such as bolts. If the connecting means is a bolt, the connected duct components can be released from their connection by removing the bolt, allowing them to be separated individually.

[0028] It is preferable that harmful substances adhere only to the inner surfaces of the multiple duct members A and B to be subjected to the duct member blocking treatment. In other words, it is preferable that the duct members A and B are placed in a clean space (hereinafter also referred to as a clean space) in which harmful substances are substantially absent. Here, "substantially free of harmful substances" means that there are no harmful substances at all, or that even if there are, the amount is such that they do not affect the human body.

[0029] The multiple duct members A and B that perform this duct member blocking treatment may be installed in a narrow space (e.g., above the ceiling, etc.) or in a non-narrow space (e.g., on a normal floor, etc.), but if some or all of them are installed in a narrow space, it will be difficult to use the greenhouse described above, and the effectiveness of the present invention will be more pronounced. The blocked duct member, whose upstream and downstream ends have been blocked by the duct member blocking process, is removed and transported to, for example, a PCB waste treatment facility for detoxification. Note that it is preferable that the partition plate and the duct member are made of the same material, as this allows them to be treated together.

[0030] The exhaust duct of the present invention may be provided with duct members C1 and C2 having contaminated inner and outer surfaces and located in a space contaminated with harmful substances, connected to the upstream and / or downstream sides of multiple duct members A and B that are to undergo duct member blocking treatment.In this case, duct members C1 and C2 can be removed (moved) before or after the duct member blocking treatment, but it is preferable to remove them before the duct member blocking treatment as this allows the work to be carried out more smoothly.

[0031] In addition, exhaust ducts include ducts that do not branch upstream and have only one air flow path, and ducts that branch upstream in two or more ways and have multiple air flow paths. For duct members that do not branch upstream, it is preferable to block the opening at one upstream end of the exhaust duct (the upstream end of the most upstream duct member A to be subjected to the duct member blocking treatment) with a partition plate before performing the duct member blocking treatment. For duct members that branch upstream in two or more ways, it is preferable to block the openings at two or more upstream ends of the exhaust duct (the upstream ends of the two or more most upstream duct members A to be subjected to the duct member blocking treatment) (i.e., all upstream end openings) with partition plates before performing the duct member blocking treatment. This effectively creates a negative pressure inside the exhaust duct and prevents harmful substances from leaking to the outside.

[0032] Hereinafter, each step constituting the exhaust duct dismantling method of the present invention will be described in detail with reference to the drawings. 1, the method for dismantling an exhaust duct of the present invention includes, for example, an air exhaust device installation step (S1), an air exhaust step (S2), a first disconnecting step (S3), a first partitioning step (S4), a second disconnecting step (S5), a second partitioning step (S6), a third disconnecting step (S7), a third partitioning step (S8), and a transporting step (S9). The second disconnecting step (S5) and the second partitioning step (S6) are steps for performing the duct member closing treatment of the present invention, and are steps that are repeatedly performed. In this embodiment, the case where the harmful substance adhering to the inner surface of the exhaust duct is PCB will be described, but the same applies to other harmful substances.

[0033] First, with reference to Figures 2 and 3, an exhaust duct 11 laid in a PCB waste treatment facility (hereinafter also simply referred to as treatment facility) 10 to which the exhaust duct dismantling method of the present invention is applied will be described. The treatment facility 10 is, for example, composed of multiple floors, and an exhaust duct 11 is laid from a lower floor 12 to an upper floor 13, passing through an attic 14. Both the lower floor 12 and the upper floor 13 are non-narrow (wide) spaces contaminated with harmful substances, and the attic 14 is a clean and narrow space that is substantially free of harmful substances. Note that in Figure 2, for ease of explanation, the lower floor 12 and the attic 14 are depicted as being at the same height.

[0034] The exhaust duct 11 is, for example, a steel plate pipe with a rectangular (quadrilateral) cross section with sides of about 50 to 100 cm, and is configured by connecting multiple duct members with a length of about 1 m, but there are no particular limitations on the size, shape, material, etc. Specifically, the multiple duct members are connected by aligning flanges provided on the upstream and downstream end peripheral edges of each duct member so that adjacent duct members face each other in the connecting direction and attaching connecting means such as bolts to these flanges, but there are no particular limitations on the connecting method.

[0035] In the exhaust duct 11, multiple duct members 15 (duct members A and B) that perform duct member blocking treatment are arranged in the attic 14, multiple duct members 16 (duct member C1) that are separately connected are arranged on the upstream side of the multiple duct members 15 (upstream side of the most upstream duct member A) on the lower floor 12 of the treatment facility 10, and multiple duct members 17 (duct member C2) that are separately connected are arranged on the downstream side of the duct members 15 (downstream side of the most downstream duct member B) on the upper floor 13. Duct member 15 arranged in the attic 14 has PCBs attached to its inner surface but its outer surface is not contaminated (uncontaminated), and duct members 16 and 17 arranged on the lower floor 12 and upper floor 13, respectively, are inner and outer surface-contaminated duct members whose inner and outer surfaces are contaminated with PCBs.

[0036] The duct member 17 located on the upper floor 13 is fitted with an exhaust fan (air exhaust device: not shown) for sucking air from the downstream end of the exhaust duct 11 and exhausting it to the outside during normal operation of the exhaust duct 11, and an activated carbon adsorption tower 18 (PCB recovery means) for adsorbing and removing PCBs contained in the exhausted air.

[0037] [Air exhaust device installation process] The air exhaust device installation process is a process of attaching and fixing the air exhaust device 19 to the duct member 17 arranged on the upper floor 13. Before attaching the air exhaust device 19, the existing exhaust fan is stopped. The air exhaust device 19 is a small, portable device that sucks in the air inside the exhaust duct 11 and exhausts it to the outside, and contains an adsorbent such as activated carbon that can adsorb PCBs contained in the sucked air. The exhaust capacity of this air exhaust device 19 should be such that it can create a negative pressure inside the exhaust duct 11 and does not interfere with the dismantling work from the standpoint of safety, etc. For example, it is preferable that the pressure inside the exhaust duct 11 can be about 0.080 to 0.098 MPa. In this embodiment, an air exhaust device 19 is installed separately, but it is also possible to use an existing exhaust fan attached to the exhaust duct 11 without using this air exhaust device 19, in which case this step is unnecessary.

[0038] [Air exhaust process (negative pressure process)] The air exhaust process is a process in which the installed air exhaust device 19 is operated to exhaust the air in the exhaust duct 11 from the downstream end side of the exhaust duct 11, thereby creating a negative pressure state inside the exhaust duct 11. The air exhaust device 19 is maintained in operation (operates continuously) without being stopped at least while the duct member blocking process (the second disconnecting step (S5) and the second partitioning step (S6)) is being performed, and maintains the negative pressure state inside the exhaust duct 11. Note that the air exhaust device 19 may be operated intermittently, for example, by operating for a predetermined time and then stopping for a predetermined time, within a range in which the negative pressure state inside the exhaust duct 11 can be maintained.

[0039] Here, duct member 16 (duct member C1), which is separately connected to the upstream side of duct member 15 that performs the duct member closing process, is located on the lower floor 12 of the processing facility 10. Therefore, if the air exhaust device 19 is operated with its upstream end open, PCBs on the lower floor 12 will be sucked into the exhaust duct 11. For this reason, the air exhaust device 19 is operated after closing the opening at the upstream end of duct member 16 with an upstream end closing plate 20. Note that the upstream end closing plate 20 can be made of, for example, a sheet or the like, but it can also be made of a material having the same configuration as a partition plate, which will be described later. This prevents PCBs present on the lower floor 12 from flowing into the exhaust duct 11.

[0040] [First disconnection (bolt removal) process] The first disconnection process is a process of disconnecting the connection between the most upstream duct member 15 that will undergo the duct member closing process and the duct member 16 that is connected to the upstream side of it. Note that this most upstream duct member 15 will first become duct member A in the second partitioning process, which will be described later. Also, reference numeral 21 in Figures 2 and 3 represents a worker who performs the duct member closing process. Specifically, in the ceiling space 14, the bolts that connect and secure the flange of the duct member 15 to the flange of the duct member 16 are removed, making the duct member 16 separable from the duct member 15. Here, only the connecting means is removed (connection is released), and the duct members 15 and 16 are not moved in principle, but only a gap is created between the duct members 15 and 16 to allow the partition plate 22 to be inserted.

[0041] [First separation process] The first partitioning step is a step of inserting a partition plate 22 into the gap between duct member 15 and duct member 16 that is created by removing the bolts, thereby closing the upstream end opening of duct member 15. At the same time, it is preferable to also close the downstream end opening of duct member 16. This partition plate 22 can be attached and fixed to the flange at the upstream end of duct member 15 using fastening means such as bolts, but there are no particular limitations as long as it can be fixed.

[0042] It is preferable that the exhaust duct made up of duct member 16, which has been disconnected from duct member 15, is moved to the lower floor 12 before the second disconnection step. At this time, the opening in the ceiling through which duct member 16 passed is closed. Alternatively, the dismantling work of duct member 15 may be continued as is, and then it may be moved to the lower floor for disposal. As mentioned above, the lower floor 12 is not a narrow space and it is easy to install a greenhouse, so it is preferable to carry out the dismantling of the duct member 16 inside this greenhouse.

[0043] On the other hand, the first disconnecting step and the first partitioning step may be performed before the air exhaust device installation step and / or the air exhaust step. That is, the first disconnecting step and the first partitioning step may be performed while exhausting the air in the exhaust duct 11 from the lower floor 12 side by an air exhaust device separate from the air exhaust device 19 (separate from the existing exhaust fan), thereby disconnecting the connection between the duct member 15 and the duct member 16 and further removing (moving) the duct member 16 in advance.

[0044] [Second disconnection (bolt removal) process] As shown in Figures 2 and 3, the second disconnection process is a process of disconnecting a duct member 15 (hereinafter also referred to as duct member A) whose upstream end opening is blocked by partition plate 22 or partition plate 24 from a duct member 15 (hereinafter also referred to as duct member B) connected to its downstream side, and constitutes part of the process of performing duct member blocking processing. Specifically, in the ceiling space 14, the bolts that connect and secure the flange of the upstream duct member A to the flange of the downstream duct member B are removed, and the connection between the two duct members A and B is released. Here, only the connecting means is removed, and a gap is created between the two duct members A and B to allow the partition plates 23 and 24 to be inserted, and the duct members A and B are not moved in principle.

[0045] [Second partitioning process] As shown in Figure 3, the second partitioning process is a process in which two partition plates 23, 24 are inserted into the gap between two duct members A and B created by removing the bolts, and one of the inserted partition plates 23 is used to block the downstream opening 25 of the upstream duct member A, and the other inserted partition plate 24 is used to block the upstream opening 26 of the downstream duct member B, and together with the second disconnecting process, this process constitutes a process of performing a duct member blocking process. Here, the two partition plates 23 and 24 can be attached and fixed to the flanges of the duct members A and B, respectively, using bolts, for example, but the means for fixing them is not particularly limited as long as they can be fixed.

[0046] The partition plates 23 and 24 are plate-shaped plates that can block the downstream opening 25 of the duct member A or the upstream opening 26 of the duct member B, respectively, and have a thickness of, for example, about 0.5 mm to 1.5 mm, preferably about 0.6 mm to 1 mm. These partition plates 23, 24 are preferably steel plates made of the same material as duct members A, B, which is preferable because subsequent final disposal, such as incineration, can be carried out under the same conditions as duct members A, B, improving workability. Note that the above-mentioned partition plate 22 and the partition plate 27 described below are also preferably made of the same material and have the same structure as partition plates 23, 24.

[0047] The second disconnecting step and second partitioning step, i.e., the duct member closing process, are repeatedly performed on all of the duct members 15. This duct member closing process is preferably performed sequentially from the upstream side of the exhaust duct 11.

[0048] Furthermore, this duct member closing process is preferably performed while exhausting the air from the exhaust duct 11 and supplying air into the duct member B on the downstream side that has been released from connection or released. Here, as a specific embodiment for supplying air into the downstream duct member B that has been disconnected or released, as shown in FIG. 3, an embodiment can be exemplified in which an air supply hole (small hole) 28 is provided in the upstream side wall of the duct member 15 to allow natural air supply into the exhaust duct 11. This makes it easier to form an air flow toward the downstream side within the exhaust duct 11, and PCBs contained in the air within the exhaust duct 11 are effectively exhausted. Note that an air supply device can also be connected to the above-mentioned hole 28 to forcibly supply air. This allows for a smoother air flow within the exhaust duct 11.

[0049] Furthermore, when air is to be supplied into the released downstream duct member B, a hole (small hole) for supplying air can be provided in the partition plate 24 to allow natural air supply into the exhaust duct 11. An air supply device can also be connected to the hole to force air supply. This hole can be formed in place of or separately from the hole formed in the side wall of the duct member 15. It is preferable that the holes formed in the side walls and partition plates of the duct member are closed at a desired stage before transport.

[0050] [Third disconnection (bolt removal) process] The third disconnection process is a process of disconnecting the connection between the most downstream duct member 15 that undergoes the duct member blocking process and the duct member 17 connected downstream of it. Note that this most downstream duct member 15 is the duct that will finally become duct member B in the second disconnection process and the second partitioning process. Specifically, in the ceiling space 14, the bolts that connect and secure the flange of the duct member 15 to the flange of the duct member 17 are removed, making the duct member 15 separable from the duct member 17. In this case, only the connecting means is removed, and a gap is created between the duct members 15 and 17 so that the partition plate 27 can be inserted, and the duct members 15 and 17 are not moved in principle.

[0051] [Third partitioning process] The third partitioning step is a step of inserting one partition plate 27 into the gap between duct member 15 and duct member 17 that is created by removing the connecting means, thereby closing the downstream end opening of duct member 15. At the same time, it is preferable to also close the upstream end opening of duct member 17. This partition plate 27 can be attached and fixed to the flange at the downstream end of duct member 15 using, for example, bolts, but there are no particular limitations as long as it can be fixed.

[0052] Duct member 17, which has been disconnected from duct member 15, is placed on upper floor 13, and since its outer surface is contaminated with PCBs, it is treated on upper floor 13. As mentioned above, upper floor 13 is not a narrow space, and it is easy to install a greenhouse, for example, so dismantling of duct member 17 is preferably carried out inside this greenhouse. The activated carbon adsorption tower 18 and exhaust fan attached to duct member 17 should also be disposed of inside this greenhouse.

[0053] [Transportation process] The transporting step is a step of transporting the duct member 15, the upstream end and downstream end of which are closed by the partition plates 24, 23, that is, the closed duct member, from the ceiling space 14. Here, for example, if a gap occurs between the opening-side periphery of the duct member 15 and the partition plates 23, 24, it is preferable to eliminate the gap by applying a sealing member such as tape, thereby further improving safety. The blocked duct material removed from the attic 14 is transported, for example, to a greenhouse installed in a non-narrow space, where it is crushed, and then transported to a low-concentration detoxification treatment facility for treatment.

[0054] As described above, the dismantling of the exhaust duct of the present invention involves dismantling the connected duct members while exhausting the air from the exhaust duct and closing the openings of the duct members, so each duct member can be safely and easily sealed and can be safely transported thereafter. Therefore, there is almost no leakage of harmful substances from the duct members into the external environment, and the risk of worker exposure is reduced.

[0055] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the configurations described in the above embodiments and includes other embodiments and modifications that are conceivable within the scope of the claims. For example, the scope of the present invention also includes a case in which the exhaust duct dismantling method of the present invention is configured by combining some or all of the above embodiments and modifications. In the above embodiment, we have described the case where an exhaust duct with harmful substances attached to its inner surface is dismantled without using a greenhouse. However, in order to be able to respond to unforeseen circumstances, a greenhouse can be installed in the space where the exhaust duct is installed, and the exhaust duct according to the present invention can be dismantled within this greenhouse. [Industrial Applicability]

[0056] INDUSTRIAL APPLICABILITY The present invention is industrially useful because it enables safe and easy dismantling of exhaust ducts having harmful substances adhering to their inner surfaces. [Explanation of symbols]

[0057] 10: PCB waste treatment facility, 11: exhaust duct, 12: lower floor, 13: upper floor, 14: ceiling, 15: duct component (duct component A, B), 16: duct component (duct component C1), 17: duct component (duct component C2), 18: activated carbon adsorption tower, 19: air exhaust device, 20: upstream end blocking plate, 21: worker, 22-24: partition plate, 25: downstream opening, 26: upstream opening, 27: partition plate, 28: hole

Claims

1. A method for dismantling an exhaust duct that has harmful substances attached to its inner surface and is made up of multiple duct members connected together, comprising the steps of: A method for dismantling an exhaust duct, characterized by repeatedly performing a duct member closing process in which the duct members are disconnected from each other while exhausting air from the downstream end of the exhaust duct, and two partition plates are inserted between the duct members, blocking the downstream opening of the upstream duct member A with one of the inserted partition plates, and blocking the upstream opening of the downstream duct member B with the other inserted partition plate.

2. 2. The method for dismantling an exhaust duct according to claim 1, wherein the duct member closing process is performed sequentially from the upstream side of the exhaust duct.

3. 2. The method for dismantling an exhaust duct according to claim 1, wherein, before the duct member closing process, the upstream end of the most upstream duct member A to be closed is closed with a partition plate.

4. 2. The method for dismantling an exhaust duct according to claim 1, further comprising the step of: carrying out the closed duct member, the closed duct member having both the upstream end and the downstream end closed, after the duct member closing process.

5. 2. The method for dismantling an exhaust duct according to claim 1, wherein the duct member blocking process is performed on a duct member that is located in a clean space that is substantially free of harmful substances.

6. A method for dismantling an exhaust duct as described in claim 5, characterized in that before the duct member blocking treatment, the connection of any duct members with contaminated internal and external surfaces that are connected upstream or downstream of the duct member to be blocked and that are placed in a space contaminated by harmful substances is released, and the duct members with contaminated internal and external surfaces are removed.

7. A method for dismantling an exhaust duct as described in claim 1, characterized in that the duct member blocking process is performed while exhausting air from the exhaust duct and supplying air into the downstream duct member B that is being disconnected or has been disconnected.

8. 8. The method for dismantling an exhaust duct according to claim 7, wherein air is supplied into the duct member through a hole provided in a side wall of the downstream duct member B.

9. 8. The method for dismantling an exhaust duct according to claim 7, wherein air is supplied into the duct member through a hole provided in the partition plate of the downstream duct member B.

10. 2. The method for dismantling an exhaust duct according to claim 1, wherein the partition plate is made of the same material as the duct member.

11. A method for dismantling an exhaust duct as described in any one of claims 1 to 10, characterized in that the harmful substance is PCB, and the concentration of PCB attached to the inner surface of the exhaust duct is at a low concentration contamination level that can be treated at a low concentration detoxification treatment facility.

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