JP7553253B2 - How to dismantle an exhaust pipe - Google Patents

Description

The present invention relates to a method for dismantling a structure, and in particular to a method suitable for dismantling an exhaust stack when work at height is required and access for workers is restricted.

As disclosed in Patent Document 1, typical dismantling of an exhaust stack involves setting up scaffolding around the outside of the stack and then cutting the stack at predetermined lengths from the top using a wire saw or similar. The technology disclosed in Patent Document 1 describes how, if the inside of the exhaust stack is contaminated with pollutants, the inside surface of the exhaust stack is scraped off before cutting to remove the contaminated areas. By adopting such a method, there is no risk of dust containing pollutants scattering to the outside due to cutting.

Patent Document 2 also discloses a method in which a platform suspended by a crane so that it can be raised and lowered is placed in a frame shape around the outer periphery of the exhaust stack, and dismantling work is carried out while moving this along the exhaust stack. In the method disclosed in Patent Document 2, a concrete crusher and a steel cutter that can also be used on the ground are mounted on the platform, and dismantling work is carried out by remotely operating these concrete crushers and steel cutters. It also discloses that debris resulting from the dismantling is dropped through the hollow part of the exhaust stack.

JP 2019-135352 A JP 2003-301615 A

The method disclosed in Patent Document 2 makes it possible to carry out dismantling work without erecting scaffolding around the exterior of the exhaust stack.
However, in order to carry out the dismantling method disclosed in Patent Document 2, a large-scale stand is required. In addition, since the stand is supported only by a hanging cable and a fall prevention cable, there is a problem that it is difficult to ensure stability during the dismantling work. Furthermore, since the debris is dropped into the exhaust stack, there is a concern that dust may be stirred up as the debris falls. For this reason, the method cannot be applied to exhaust stacks that have areas containing pollutants, as disclosed in Patent Document 1.

The present invention aims to provide an exhaust stack dismantling method that can simplify the structure of the stand, ensures work stability during dismantling work, and is compatible with a variety of exhaust stacks.

The exhaust stack dismantling method of the present invention, which is intended to achieve the above-mentioned objective, is a method for dismantling an exhaust stack in which a dismantling machine equipped with at least a main arm and a clamp arm is mounted on a platform suspended from a hoist that is suspended from the end of the arm of a lifting means that can extend the arm to a position higher than the height of the exhaust stack to be dismantled, and the dismantling machine is hoisted together with the platform to perform dismantling work, and is characterized in that, with a part of the exhaust stack clamped by the clamp arm, the main arm is used to dismantle the parts other than the part clamped.

In addition, in the exhaust stack dismantling method having the above-mentioned characteristics, it is desirable that the dismantling heavy machine is equipped with a dismantling piece support arm, and dismantling is performed by the main arm while the dismantling pieces are supported by the dismantling piece support arm. By having such a characteristic, there is no risk of the dismantling pieces falling when they are cut out.

In addition, in the exhaust stack dismantling method having the above-mentioned characteristics, it is desirable to transfer the dismantled pieces dismantled by the demolition heavy machinery to a lifting cage of an aerial work vehicle that is extended from the ground so that they are close to the dismantling area, and then lower them. With this characteristic, it is no longer necessary to lower the demolition heavy machinery to the ground one by one, which improves the efficiency of the dismantling work.

Furthermore, in the exhaust stack dismantling method having the above-mentioned characteristics, the hoisting tool may be provided with a rotating device, and when the lifting means moves the suspension position of the frame along the periphery of the exhaust stack, the frame may be rotated so that the exhaust stack is positioned in front of the demolition heavy machine. By having such a characteristic, good workability can be ensured regardless of where the demolition heavy machine is positioned around the exhaust stack.

The exhaust stack dismantling method having the above-mentioned characteristics allows the construction of the mounting frame to be simplified. It also ensures operational stability during dismantling work and makes it possible to accommodate a variety of exhaust stacks.

FIG. 13 is a diagram showing the configuration when dismantling an exhaust stack using a crawler-type crane (lifting means). FIG. 13 is a diagram showing the configuration when dismantling an exhaust stack using a climbing crane (lifting means). FIG. 2 is a diagram for explaining the configuration of an exhaust stack to be dismantled in the embodiment. FIG. 2 is a diagram for explaining the configuration of a stand and a dismantling heavy machine used in the embodiment. 10A to 10C are diagrams showing the state of exhaust stack dismantling work of the exhaust stack according to the embodiment. 13 is a diagram for explaining a disassembly procedure for cutting out disassembly pieces. FIG. FIG. 2 is a flow chart for explaining an exhaust stack dismantling method according to an embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the exhaust stack dismantling method of the present invention will be described in detail with reference to the drawings.
[Exhaust Stack]
First, the structure of an exhaust stack 10 to be dismantled in the following embodiment will be described with reference to Figures 1 to 3. The exhaust stack 10 to be dismantled in the following embodiment is composed of an exhaust stack body 12 and a supporting steel frame 14. The exhaust stack body 12 is provided with emergency gas treatment system piping (hereinafter referred to as SGTS piping 16) inside (see Figure 3). Note that both the exhaust stack body 12 and the SGTS piping 16 according to this embodiment are composed of materials such as carbon steel that have excellent corrosion resistance, chemical resistance, and environmental resistance.

The support steel frame 14 is an element that is arranged around the outer periphery of the exhaust stack body 12 and plays a role in supporting the exhaust stack body 12. The support steel frame 14 has a so-called truss structure, and is configured in a tower shape with a planar structure that widens toward the lower end.

[Lifting means]
The lifting means 18 may have any specific configuration as long as it can extend the arm 20 to a position higher than the exhaust stack 10 to be dismantled and can lift the platform 30 on which the dismantling heavy machinery 40, the details of which will be described later, is mounted. For example, it may be a crawler type crane as shown in Figure 1 or a climbing type crane as shown in Figure 2.

The exhaust stack dismantling method according to this embodiment is configured to deploy an aerial work vehicle 22 in addition to the lifting means 18 near the exhaust stack 10. By transferring the dismantled pieces 60 (see Figures 5 and 6) dismantled by the demolition heavy machinery 40, the details of which will be described later, to a lifting cage 26 provided at the tip of the arm 24 of the aerial work vehicle 22, it is no longer necessary to lower the platform 30 to the ground each time a dismantled piece 60 is cut out, improving work efficiency.

[Mounting stand]
The platform 30 may be any platform that has sufficient load-bearing capacity and durability to allow the dismantling machine to be mounted thereon and dismantling work to be performed. The platform 30 shown in Fig. 4 is plate-shaped, and the dismantling machine 40 is fixed to the platform.

The platform 30 is lifted up via a balance 32 placed on top of the lifting machine 40. The balance 32 is suspended from the hoist 20a of the lifting means 18 via a horizontal device 34 and a swivel device 36. The horizontal device 34 is not shown in detail, but it is sufficient if it is equipped with a load detection means and a towing means corresponding to each of the multiple suspension parts defined on the balance 32. In the horizontal device 34 configured in this way, the length of each suspension part is adjusted according to the inclination detected by the load inclination detection means, so that the platform suspended via the balance 32 can be kept level.

The rotation device 36, like the horizontal device 34, is not shown in detail, but it is sufficient if it is equipped with at least a gyro sensor and a flywheel inside and can rotate horizontally by operation while suppressing automatic rotation due to the influence of wind, etc.

[Demolition heavy machinery]
The dismantling heavy machine 40 has a base 42 and a swivel base 44, and the base 42 is provided with a clamp arm 46, and the swivel base 44 is provided with a main arm 48 and a dismantling piece support arm 50. The base 42 is the foundation of the dismantling heavy machine 40, and is fixed to the stand 30 as described above in this embodiment. The clamp arm 46 provided on the base 42 is an element for clamping a part of the exhaust stack 10 to be dismantled. By clamping a part of the exhaust stack 10, the dismantling heavy machine 40 suspended from the arm 20 of the lifting means 18 via the hoist 20a can be stabilized. Therefore, the stand 30 does not need to be large and stable, and the stand 30 can be made small.

The swivel table 44 is a table that can rotate horizontally with the base 42 as the starting point. The main arm 48 is an arm used to dismantle the exhaust stack 10, and in this embodiment, a steel frame cutter 48a is attached to the tip, enabling it to cut the metallic exhaust stack body 12, the SGTS piping 16, and the supporting steel frame 14. The main arm 48 is configured to have four degrees of freedom: three axes in the elevation direction and one axis in the rotation direction.

The dismantling piece support arm 50 is positioned on the lower side of the swivel base 44 and is arranged so as to face the same direction as the main arm 48. The tip of the dismantling piece support arm 50 is provided with a gripping means 50a for supporting the dismantling piece 60. The dismantling piece support arm 50 is also configured to be extendable and retractable with the swivel base 44 as its starting point.

The lifting means 18, the slewing device 36, and the dismantling heavy machine 40 configured as described above can all be remotely operated using an operating means (not shown). This configuration makes it possible to dismantle the exhaust stack 10 even in places where access by workers is restricted.

[Disassembly method]
Next, a method for dismantling the exhaust stack 10 configured as described above using the lifting means 18, the aerial work platform 22, the platform 30, and the demolition heavy machinery 40 as described above will be described with reference to FIG. 7. The exhaust stack 10 is dismantled from the tip side of the exhaust stack body 12. The specific dismantling procedure is to remove the walkway 12a provided at the tip of the exhaust stack body 12. After removing the walkway 12a, the exhaust stack body 12 is dismantled to expose the SGTS piping 16. After that, the exposed SGTS piping 16 is dismantled, and the exhaust stack body 12 is dismantled again. When the dismantling of the exhaust stack body 12 reaches the part where the supporting steel frame 14 is arranged, the supporting steel frame 14 is dismantled to a predetermined extent, and then the exhaust stack body 12 is dismantled to expose the SGTS piping 16. The subsequent dismantling work may be performed repeatedly in the order of the SGTS piping 16, the supporting steel frame 14, and the piping body 12.

When carrying out the above-mentioned dismantling method, first, the lifting means 18 and the aerial work vehicle 22 are deployed near the exhaust stack 10 to be dismantled. Here, the lifting means 18 is sufficient if it is capable of lifting the platform 30 carrying the dismantling heavy machine 40, the horizontal device 34, and the swivel device 36, and the tip of the arm 20 is positioned at the top of the exhaust stack 10 when the arm 20 is lowered (Step 10: Deploy the lifting means).

After the lifting means 18 and the aerial work vehicle 22 have been deployed, the platform 30 carrying the dismantling heavy machine 40 is lifted using the lifting means 18. At this time, it is desirable to use the above-mentioned leveling device 34 and swivel device 36 to adjust the platform 30 so that it does not tilt or point in an unexpected direction, and to raise and lower the platform 30 in a stable state. In addition, the aerial work vehicle 22 extends the arm 24 so as to move the lifting cage 26 as close to the platform 30 as possible. If it is not possible to move the lifting cage 26 close to the platform 30, the arm 24 can be extended to a height that allows it to be raised (Step 20: Lifting the platform).

After the platform 30 has been lifted to the designated working position, the clamp arm 46 of the demolition machine 40 is used to grasp a portion of the exhaust stack 10 (see Figure 5) to ensure the stability of the demolition machine 40 during dismantling work (Step 30: Fixing with the clamp arm).

After gripping a portion of the exhaust stack 10 with the clamp arm 46, the steel frame cutter 48a of the main arm 48 makes a pair of cuts so that part of the exhaust stack body 12 becomes a strip (the cuts are shown by the dashed lines in FIG. 6(A)). This determines the width of the dismantled pieces 60 (slices) to be cut out by dismantling. Here, the parts to be cut with the steel frame cutter 48a are parts other than the part gripped by the clamp arm 46 (step 40: Cut widthwise).

After making a cut in the exhaust pipe body 12, the tip of the rectangular plate piece is grasped by the tip of the main arm 48 (steel frame cutter 48a) and bent outward as shown in FIG. 6(B). A part (e.g., the tip side) of the dismantled piece 60 bent outward is supported by the gripping means 50a provided on the dismantled piece support arm 50. After the dismantled piece 60 is grasped by the gripping means 50a, the base end side (the bending base point side) of the dismantled piece 60 is cut by the steel frame cutter 48a, and the removal of the dismantled piece 60 is completed. The size of the dismantled piece 60 to be removed in one operation is set to a weight range that satisfies both the allowable load of the lifting means 18 and the allowable load of the demolition heavy machine 40. Therefore, as shown by the dashed lines in FIG. 5, the exhaust pipe 10 (exhaust pipe body 12) is cut into multiple pieces (step 50: Removal of dismantled pieces).

The cut dismantled pieces 60 are transferred from the dismantled piece support arm 50 to the main arm 48 and transferred to the lifting cage 26 of the aerial work vehicle 22 waiting near the dismantling work site. If the lifting cage 26 of the aerial work vehicle 22 cannot be extended to the vicinity of the dismantling work site, the platform 30 is moved by the lifting means 18 to the minimum extent necessary, and the demolition heavy machine 40 is brought closer to the lifting cage 26 of the aerial work vehicle 22, after which the dismantled pieces 60 are transferred (step 60: Transfer of dismantled pieces).

After transferring the dismantling pieces 60 to the lifting cage 26 of the aerial work vehicle 22, the demolition heavy machine 40 returns to the dismantling work of the exhaust stack 10. Meanwhile, the aerial work vehicle 22 moves the dismantling pieces 60 transferred to the lifting cage 26 to the ground. Here, if the aerial work vehicle 22 has a sufficient weight capacity, the dismantling pieces 60 may be lowered to the ground after the transfer work from the demolition heavy machine 40 is repeated multiple times (step 70: lowering the dismantling pieces).

The dismantling work of the exhaust stack 10 is performed by moving the suspension position of the dismantling heavy machine 40 each time a dismantling piece 60 is cut off. Specifically, the suspension position of the dismantling heavy machine is rotated in a circumferential direction with the center of the exhaust stack 10 as the base point. When moving the dismantling position, the rotation device 36 is operated so that the exhaust stack 10 is positioned in front of the dismantling heavy machine 40. In this way, the dismantling work of the exhaust stack 10 is performed by repeating the above-mentioned steps 30 to 70 for the exhaust stack body 12, SGTS piping 16, and supporting steel frame 14 in sequence.

[effect]
According to the exhaust stack dismantling method as described above, it is possible to shorten the construction period since it is not necessary to construct scaffolding around the exhaust stack 10. In addition, the cost for constructing the scaffolding can be reduced.

The lifting means 18 lifts the demolition machine 40, and the demolition work is carried out by remote control, eliminating the need for workers to enter the work site. This makes it possible to work in dangerous areas where human access is restricted.

The demolition work is carried out by transferring the dismantled pieces 60 to the lifting cage 26 of the aerial work vehicle 22 and lowering them to the ground, so the dismantled pieces 60 can be lowered to the ground more efficiently than by raising and lowering the platform 30 on which the demolition heavy machinery 40 is mounted. In addition, no dust is stirred up, as occurs when the dismantled pieces 60 are dropped, so the impact on the surrounding environment can be kept small.

In the above embodiment, the material of the exhaust pipe body 12 is carbon steel, etc., but the dismantling method of the present invention can also be applied to exhaust pipes made of reinforced concrete, etc.

10...Exhaust stack, 12...Exhaust stack body, 12a...Walkway, 14...Support steel frame, 16...SGTS piping, 18...Lifting means, 20...Arm, 20a...Hanging device, 22...Aerial work platform, 24...Arm, 26...Lifting cage, 30...Frame, 32...Balance, 34...Leveling device, 36...Swivel device, 40...Demolition heavy equipment, 42...Base, 44...Swivel table, 46...Clamp arm, 48...Main arm, 48a...Steel frame cutter, 50...Dismantled piece support arm, 50a...Gripping means, 60...Dismantled piece.

Claims (3)

A method for dismantling an exhaust stack, comprising the steps of: mounting a dismantling heavy machine having at least a main arm and a clamp arm on a platform suspended from a hoisting tool suspended from the tip of an arm of a lifting means capable of extending the arm to a position higher than the height of the exhaust stack to be dismantled; and hoisting the dismantling heavy machine together with the platform to perform dismantling work,
The dismantling heavy machine includes a dismantling piece support arm,
An exhaust stack dismantling method, characterized in that, while a portion of the exhaust stack is clamped by the clamp arm and the dismantled piece is supported by the dismantled piece support arm , the main arm is used to dismantle the section above the portion clamped by the clamp arm . The exhaust stack dismantling method according to claim 1 , characterized in that the pieces dismantled by the demolition heavy machinery are transferred to a lifting cage of an aerial work vehicle extended from the ground so as to approach the dismantling site, and then lowered. The hoist is provided with a rotating device, and when the lifting means moves the hanging position of the frame along the circumference of the exhaust stack,
3. The exhaust stack dismantling method according to claim 1, further comprising rotating the platform so that the exhaust stack is positioned in front of the demolition heavy machine.

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