Continuous Unloader

Abstract

To provide a continuous unloader capable of handling a pellet-formed load.SOLUTION: A continuous unloader 40, to be switched over to a pneumatic unloader, comprises a bucket elevator 47, a vertical pipe 1 allowed to be attached to the bucket elevator, and a vacuum pump 2 for supplying negative pressure to the vertical pipe.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a continuous unloader.

Background Art

[0002] Generally, in a thermal power plant, coal transported by a ship is unloaded by a continuous unloader (also called a coal unloader) installed at the port. The unloaded coal is conveyed to a nearby storage facility by an overland conveyor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in recent years, in order to reduce the amount of carbon dioxide emissions in consideration of the global environment, it has been considered to change the fuel in a thermal power plant from coal to an alternative fuel with a smaller environmental impact, typically biomass fuel.

[0005] Biomass fuel is a pellet-shaped or granular fuel with a smaller average particle size than coal. When this is unloaded by a continuous unloader, dust may scatter during operation, which may have an adverse impact on the environment.

[0006] Therefore, the present disclosure has been devised in view of such circumstances, and its object is to provide a continuous unloader capable of handling pellet-shaped loads.

Means for Solving the Problems

[0007] According to one aspect of the present disclosure, a continuous unloader that can be switched to a pneumatic unloader, a bucket elevator, A vertical pipe that can be attached to the bucket elevator, A vacuum pump for supplying negative pressure to the vertical pipe, A continuous unloader is provided, characterized by comprising the following features.

[0008] Preferably, the continuous unloader is The boom and A horizontal pipe arranged on the boom and connectable to the vertical pipe, A receiver tank interposed between the horizontal pipe and the vacuum pump, It is equipped with.

[0009] Preferably, the bucket elevator includes a bucket elevator casing. The vertical pipe can be installed inside the bucket elevator casing.

[0010] Preferably, the bucket elevator includes a bucket chain disposed within the bucket elevator casing. The bucket chain comprises a chain and a plurality of buckets detachably attached to the chain. When switching to the pneumatic unloader, the bucket is removed, and the vertical tube is attached to the portion of the chain from which the bucket was removed.

[0011] Preferably, the vertical tube is composed of a plurality of divided vertical tubes that are divided in the longitudinal direction.

[0012] According to other aspects of this disclosure, A method for switching the continuous unloader to the pneumatic unloader, The first step is to remove the bucket from the chain, A second step involves attaching the divided vertical pipe to the portion of the chain from which the bucket has been removed, at a position below the bucket elevator casing. A third step of raising the chain, At a position below the bucket elevator casing, attach another split vertical pipe to the part of the chain from which the bucket has been removed, and a fourth step of connecting the other split vertical pipe to the split vertical pipe; A switching method characterized by comprising the above and is provided.

Effects of the Invention

[0013] According to the present disclosure, a continuous unloader capable of handling pellet-like loads can be provided.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic diagram of a continuous unloader according to an embodiment of the present disclosure. [Figure 2] It is a schematic diagram showing the unloader before attaching the vertical pipe. [Figure 3] It shows details of the attachment part of the bucket and the vertical pipe, and is a cross-sectional view taken along line III-III of FIG. 1. [Figure 4] It shows details of the attachment part of the vertical pipe, and is a view taken in the direction of arrow IV of FIG. 3. [Figure 5] It is a flowchart showing a method of switching to a pneumatic unloader. [Figure 6] It is a schematic diagram showing a method of switching to a pneumatic unloader.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that it should be noted that the present disclosure is not limited to the following embodiments.

[0016] FIG. 1 is a schematic diagram of a continuous unloader according to an embodiment of the present disclosure. For convenience, the directions of front, rear, left, right, up, and down are defined as shown in the drawing.

[0017] On the land of the pier where the thermal power plant is located, a pair of rails R are installed along the quay wall, and a continuous unloader 40 is mounted on these rails R so as to be able to travel on them. The unloader 40 has a running frame 41 with wheels that can travel on the rails R, and a swivel frame 42 that is rotatably mounted on the upper surface of the running frame 41. The swivel frame 42 is rotatable about a swivel axis that extends in the vertical direction.

[0018] The base end of the boom 43 and the middle section of the balancing lever 44 are rotatably attached to the slewing frame 42. Furthermore, the top frame 45 is rotatably attached to the tip of the boom 43 and the tip of the balancing lever 44. These slewing frame 42, boom 43, balancing lever 44, and top frame 45 constitute a four-bar linkage mechanism or a parallel linkage mechanism.

[0019] One end of a cylinder 46, which is a luffing actuator, is rotatably attached to the slewing frame 42, and the other end of the cylinder 46 is rotatably attached to the middle part of the balancing lever 44. The boom 43 can be raised and lowered by extending and retracting the cylinder 46.

[0020] Furthermore, the pivot axes in these rotatable mounting parts extend horizontally (left-right) and are arranged parallel to each other.

[0021] A bucket elevator 47 is rotatably mounted on the top frame 45. The bucket elevator 47 is rotatable around a pivot axis that extends vertically.

[0022] The bucket elevator 47 comprises a bucket elevator casing 48 extending vertically through the top frame 45, and a scraping section 49 located below the bucket elevator casing 48. A drive sprocket 50 is provided in the upper part of the bucket elevator casing 48. The scraping section 49 comprises a rear sprocket 51, a front sprocket 52, a link mechanism 53 connecting the rear sprocket 51 and the front sprocket 52 to the lower end of the bucket elevator casing 48, and an extension / retraction cylinder (not shown) for extending and retracting the scraping section 49 horizontally by changing the distance between the rear sprocket 51 and the front sprocket 52.

[0023] The bucket elevator 47 also includes a bucket chain 56. The bucket chain 56 comprises an endless chain 54 and a plurality of buckets 55 attached at equal intervals along the longitudinal direction of the chain 54. The chain 54 is wrapped around the drive sprocket 50, the rear sprocket 51, and the front sprocket 52. The bucket chain 56 is located inside the bucket elevator casing 48, except for the portion of the scraping section 49 that is located below the bucket elevator casing 48.

[0024] When unloading coal as cargo from the cargo hold of a ship (not shown) moored alongside the pier, a bucket elevator 47 is inserted into the cargo hold through the ship's hatch, and a scraping unit 49 is placed on top of the cargo inside the hold. The bucket elevator 47 is then operated, and a drive sprocket 50 drives a chain 54 in a circulating manner. As a result, the cargo is successively scraped up by multiple buckets 55, raised through the bucket elevator casing 48, and discharged onto a boom conveyor 57 provided on the boom 43. After that, the cargo is dropped through a chute 58 provided on the slewing frame 42 and the traveling frame 41, and then discharged onto a land conveyor 60 via a transfer conveyor 59 on the traveling frame 41, and transported by the land conveyor 60 to a storage facility (not shown).

[0025] During this lifting operation, the length, position, and orientation of the scraping section 49 are optimally adjusted according to the position, condition, and posture of the load being scraped. The length of the scraping section 49 is changed by the extension and retraction of its telescopic cylinder. The position of the scraping section 49 is changed by changing the positions of the boom 43 and the traveling frame 41. The orientation of the scraping section 49 is changed by the rotation of the bucket elevator 47.

[0026] Since the operation of the unloader 40, including this series of operations, is performed manually by an operator, the unloader 40 is provided with an operator's cab 61.

[0027] As mentioned earlier, in recent years, with the aim of reducing carbon dioxide emissions while considering the global environment, there has been consideration to changing the fuel used in thermal power plants from coal to alternative fuels with a lower environmental impact, typically biomass fuel. Biomass fuel is a pellet or granular fuel with a smaller average particle size than coal. When this is unloaded using a continuous unloader 40, dust is scattered during the operation, which could have a negative impact on the environment.

[0028] Therefore, in this embodiment, the unloader 40 can be switched to a pneumatic unloader. Since the pneumatic unloader lifts the load by suction, it generates almost no dust even when handling pellet-shaped loads. For this reason, the pneumatic unloader is suitable for pellet-shaped loads. According to this embodiment, since the unloader 40 can be switched to a pneumatic unloader, it is possible to handle pellet-shaped loads effectively.

[0029] The unloader 40 is equipped with the necessary components for switching to a pneumatic unloader. Specifically, the unloader 40 includes a vertical tube 1 that can be attached to the bucket elevator 47 to suck up the load, and a vacuum pump 2 for supplying negative pressure to the vertical tube 1. The vertical tube 1 extends vertically along the axial direction of the bucket elevator casing 48.

[0030] The unloader 40 also includes a horizontal pipe 3 positioned on the boom 43 and connectable to the vertical pipe 1, and a receiver tank 4 interposed between the horizontal pipe 3 and the vacuum pump 2.

[0031] The vacuum pump 2 is located inside the machine room 5, which is installed on the slewing frame 42. The receiver tank 4 is also installed on the slewing frame 42. The receiver tank 4 is a tank for collecting the sucked load and has a bag filter 7 inside. The top of the vacuum pump 2 and the receiver tank 4 are connected by a suction pipe 6. The negative pressure generated by the vacuum pump 2 is applied to the downstream side of the bag filter 7. As a result, the load is concentrated and captured on the upstream side of the bag filter 7. The captured load is dropped onto the boom conveyor 57 and discharged.

[0032] The horizontal tube 3 extends along the boom 43. The downstream end of the horizontal tube 3 is connected to the receiver tank 4 via a cylindrical joint 8. This allows the horizontal tube 3 to rotate relative to the receiver tank 4 when the horizontal tube 3 rises and falls with the rise and fall of the boom 43.

[0033] The horizontal pipe 3 has a curved section 9 at its upstream end that is bent diagonally downward toward the bucket elevator casing 48 directly below the top frame 45, a connecting pipe 10 that can be connected to the upper end of the vertical pipe 1, and a cylindrical joint 11 that rotatably connects the curved section 9 and the connecting pipe 10. The pivot point of the cylindrical joint 11 is coaxial with the pivot point of the top frame 45 relative to the boom 43. This allows the vertical pipe 1 to rotate relative to the horizontal pipe 3 when the top frame 45 rotates relative to the boom 43 during the luffing of the boom 43.

[0034] Figure 2 shows the unloader 40 before the vertical pipe 1 is installed (or before the vertical pipe 1 is installed). As can be seen from Figure 2, the vertical pipe 1 can be installed inside the bucket elevator casing 48, which is located below the top frame 45. Figure 1 shows the unloader 40 after the vertical pipe 1 is installed (or with the vertical pipe 1 installed). In Figure 1, for convenience, the bucket 55 is attached to the chain 54, but in reality, the bucket 55 is removed from the chain 54, as will be described later.

[0035] As shown in Figures 1 and 2, when the vertical pipe 1 is installed, the upper end of the vertical pipe 1 protrudes from inside the bucket elevator casing 48 to outside the casing through a window 12 provided in the casing. The upper end of the vertical pipe 1 is formed by an upper flexible pipe 13. By bending the upper flexible pipe 13, the upper end of the vertical pipe 1 can be smoothly moved outside the casing. The upper ends of the vertical pipe 1 and the upper flexible pipe 13 are detachably connected to the upstream end of the connecting pipe 10 by a flange.

[0036] The vertical pipe 1 is composed of multiple divided vertical pipes 14 that are divided in the longitudinal direction. The vertical pipe 1 is formed by sequentially connecting these multiple divided vertical pipes 14. The uppermost divided vertical pipe 14 is formed by an upper flexible pipe 13. The lowermost divided vertical pipe 14 is formed by a lower flexible pipe 15. The lower flexible pipe 15 has a nozzle 16 at its lower end, which serves as a suction port for the cargo. The bending of the lower flexible pipe 15 prevents damage to the bottom plate of the cargo hold when the nozzle 16 hits it.

[0037] The vertical pipe 1 protrudes downward from the lower end 17 of the bucket elevator casing 48.

[0038] When switching to the pneumatic unloader, the bucket 55 is removed from the chain 54. Then, the vertical tube 1 is attached to the part of the chain 54 where the bucket 55 was removed.

[0039] Figures 3 and 4 show details of the attachment points of the bucket 55 and vertical pipe 1 to the chain 54. Figure 3 is a cross-sectional view taken along line III-III in Figure 1, and Figure 4 is a view taken along arrow IV in Figure 3.

[0040] A pair of chains 54 are provided inside the bucket elevator casing 48. The chain 54 has a forward-side chain section 18 that is raised when scraping coal and a return-side chain section 19 that is lowered. In the illustrated example, a bucket 55 is attached to the return-side chain section 19 and a vertical pipe 1 is attached to the forward-side chain section 18. However, as shown in Figure 2, in the unloader 40 before switching to the pneumatic unloader (for convenience, referred to as the standard unloader), the bucket 55 is attached to both the forward-side chain section 18 and the return-side chain section 19, and thus along the entire length of the chain 54. In the chain circulation direction during scraping, the forward-side chain section 18 extends vertically from the rear sprocket 51 to the drive sprocket 50, and the return-side chain section 19 extends from the drive sprocket 50 to the front sprocket 52.

[0041] A pair of stays 20 are attached to the bucket 55. Brackets 21 are attached to a pair of chains 54 at predetermined intervals along the longitudinal direction (equally spaced in this embodiment). The stays 20 are attached to the brackets 21 by bolts 22. This allows the bucket 55 to be detachably attached to the chains 54.

[0042] Similarly, a pair of stays 23 are attached to the vertical pipe 1. On the other hand, the aforementioned bracket 21 remains on the part of the chain 54 from which the bucket 55 has been removed (the forward-side chain section 18). The vertical pipe 1 is attached using this bracket 21 in common. That is, the pair of stays 23 provided on the vertical pipe 1 are each attached to the bracket 21 by bolts 24. In this way, the vertical pipe 1 is detachably attached to the chain 54.

[0043] The divided vertical pipes 14 (referred to as standard divided vertical pipes), excluding the upper flexible pipe 13 and the lower flexible pipe 15, have the same configuration. As shown in Figure 4, these divided vertical pipes 14 have flanges 25 at their upper and lower ends for connection. In addition, a pair of left and right stays 23 are attached to each of these divided vertical pipes 14 by welding or the like at two locations, upper and lower, symmetrically located at the center in the length L direction.

[0044] The mounting pitch P of the bucket 55, i.e., the mounting pitch of the bracket 21, is constant (for example, 1.2m). Correspondingly, the distance between the upper and lower stays 23 in the divided vertical pipe 14 is also equal to the mounting pitch P. On the other hand, the distance between the upper stay 23 and the upper end of the divided vertical pipe 14 is P / 2, and the distance between the lower stay 23 and the lower end of the divided vertical pipe 14 is also P / 2. The length L of the divided vertical pipe 14 and the mounting positions of the upper and lower stays 23 are set to satisfy these relationships.

[0045] This makes it possible to attach the divided vertical pipes 14 and, consequently the vertical pipe 1, to each bracket 21 with an even load, thereby improving the support balance after the vertical pipe 1 is installed.

[0046] Furthermore, the number of stays 23 in the length L direction of the divided vertical pipe 14 is not limited to two, but may be three or more. However, even in this case, it is preferable that the spacing between the stays 23 be equal to the mounting pitch P, with the distance between the uppermost stay 23 and the upper end of the divided vertical pipe 14 being P / 2, and the distance between the lowermost stay 23 and the lower end of the divided vertical pipe 14 being P / 2.

[0047] The number of stays 23 in the length L direction of the divided vertical pipe 14 may be one. In this case, it is preferable that the distance between the stay 23 and the upper end of the divided vertical pipe 14 be P / 2, and the distance between the stay 23 and the lower end of the divided vertical pipe 14 be P / 2.

[0048] Next, we will explain the switching method for switching from the standard unloader 40 to the pneumatic unloader. This switching method, as shown in Figure 5, consists of the following steps. (1) First step S101: Remove the bucket 55 from the chain 54. (2) Second step S102: Install the divided vertical pipe 14 on the part of the chain 54 from which the bucket 55 has been removed, at a position below the bucket elevator casing 48. (3) The third step S103 involves raising the chain 54. (4) A fourth step S104 in which, at a position below the bucket elevator casing 48, another divided vertical pipe 14 is attached to the part of the chain 54 from which the bucket 55 has been removed, and this other divided vertical pipe 14 is connected to the already attached divided vertical pipe 14. (5) Step 5 S105 is a repetition of Step 3 S103 and Step 4 S104.

[0049] The switching method will be explained in more detail below with reference to Figures 6(A) to (E).

[0050] As shown in Figure 6(A), the first step S101 involves removing all buckets 55 from the chain 54.

[0051] Next, as shown in Figure 6(B), in the second step S102, the divided vertical pipe 14, i.e., the upper flexible pipe 13, which is ultimately located at the uppermost end, is attached to the forward-side chain section 18 at a position below the bucket elevator casing 48. The length L1 of the upper flexible pipe 13 in its straight state (unbent state) is smaller than the vertical distance H between the lower end 17 of the bucket elevator casing 48 and the lowest position of the scraping section 49. Therefore, the upper flexible pipe 13 can be easily and without hindrance attached to the forward-side chain section 18, which extends vertically, in the open space directly below the bucket elevator casing 48.

[0052] Since workers can stand on the cargo, the bottom plate of the ship's hold, or land below the bucket elevator casing 48, installation work can be easily performed.

[0053] Next, as shown in Figure 6(C), in the third step S103, the drive sprocket 50 is rotated by a predetermined angle in the forward direction during scraping, raising the forward chain section 18 by the length L1 of the upper flexible pipe 13. Then, the standard divided vertical pipe 14 is attached to the forward chain section 18 below the upper flexible pipe 13. The standard divided vertical pipe 14 is also connected to the upper flexible pipe 13. When connecting, the flanges 25, 25 of both are fastened with bolts. Since the length L of the standard divided vertical pipe 14 is also smaller than the vertical distance H, the standard divided vertical pipe 14 can be easily installed without any problems. In addition, the installation work is easy because the worker can perform the work while standing.

[0054] Next, as shown in Figure 6(D), in the fifth step S105, the third step S103 and the fourth step S104 are repeated. That is, as before, the drive sprocket 50 is rotated forward to raise the forward-side chain section 18 by the length L of the standard divided vertical pipe 14. Then another standard divided vertical pipe 14 is attached to the forward-side chain section 18 below the standard divided vertical pipe 14. At the same time, this other standard divided vertical pipe 14 is connected to the standard divided vertical pipe 14 that has already been attached.

[0055] By repeating the third step S103 and the fourth step S104 in this way, the vertical pipe 1 in the process of being assembled is sequentially inserted into the bucket elevator casing 48 and lifted up, while at the same time, the divided vertical pipes 14 are connected one after another and assembled.

[0056] As shown in Figure 6(E), during the final chain hoisting, the upper flexible pipe 13 at the top protrudes out of the bucket elevator casing 48 through the window 12. Then, below the already installed standard segmented vertical pipe 14 at the bottom, the lower flexible pipe 15 is attached to the forward-side chain section 18. At the same time, the lower flexible pipe 15 is connected to the standard segmented vertical pipe 14 at the bottom. This completes the work at the lower position.

[0057] Meanwhile, at the upper position, the upper flexible pipe 13 is connected to the connecting pipe 10. The flanges of both are fastened together with bolts. This completes the work at the upper position, and the switching operation is finished. The standard unloader 40 is then switched to the pneumatic unloader.

[0058] Such a switch occurs, for example, when the cargo being handled changes from coal to pelletized biomass fuel (biomass pellets). When the pneumatic unloader is in operation, the vacuum pump 2 is activated. This generates suction at the nozzle 16, and the cargo in the cargo hold is sucked into the nozzle 16. The sucked-in cargo rises through the vertical pipe 1, moves through the horizontal pipe 3, is captured in the receiver tank 4, and then dropped onto the boom conveyor 57. After that, it is transported to nearby storage facilities via the same route as when handling coal.

[0059] Thus, according to this embodiment, when the load is changed to a pelletized load, the standard unloader 40 can be switched to a pneumatic unloader in response. Therefore, dust generation when handling pelletized loads can be suppressed or prevented, and pelletized loads can be handled appropriately.

[0060] Furthermore, according to this embodiment, when switching to the pneumatic unloader, the vertical pipe 1 can be assembled at a lower position while being pulled up using the drive sprocket 50 and chain 54 of the bucket elevator 47. Therefore, the switching operation can be performed without using cargo handling machinery such as cranes, and the switching operation can be made easier.

[0061] Furthermore, when switched to the pneumatic unloader, the vertical tube 1 is installed inside the bucket elevator casing 48. This allows for a more compact configuration compared to when the vertical tube 1 is installed outside the bucket elevator casing 48. It also makes handling easier even in relatively narrow cargo holds. Additionally, while collision prevention detection wires (not shown) are installed outside the bucket elevator casing 48, placing the vertical tube 1 inside the bucket elevator casing 48 prevents interference with these detection wires.

[0062] Furthermore, when switching to the pneumatic unloader, the vertical tube 1 is attached to the section of the chain 54 from which the bucket 55 has been removed. This allows the vertical tube 1 to be suitably installed in the narrow space within the bucket elevator casing 48. Note that simply removing the bucket 55 would worsen the weight balance, but in this embodiment, since the vertical tube 1 is installed in place of the bucket 55, the weight balance can be maintained appropriately.

[0063] The vertical pipe 1 is composed of multiple segmented vertical pipes 14 that are divided in the longitudinal direction. Therefore, the installation work of the vertical pipe 1 is made easier because the short segmented vertical pipes 14 can be assembled sequentially in the space below the bucket elevator casing 48.

[0064] Although embodiments of this disclosure have been described in detail above, various other embodiments and modifications of this disclosure are conceivable.

[0065] (1) For example, when switching to a pneumatic unloader, it is not necessary to remove all of the buckets 55. Only about half of the buckets 55 in the area necessary for attaching the vertical pipe 1 (forward-side chain section 18) may be removed.

[0066] (2) When switching to the pneumatic unloader, the removal of the bucket 55 and the attachment of the split vertical pipe 14 may be repeated alternately.

[0067] (3) If possible, the vertical pipe 1 may be placed outside the bucket elevator casing 48. For example, the vertical pipe 1 may be attached to the outer surface of the bucket elevator casing 48.

[0068] (4) After switching to the pneumatic unloader, the reverse procedure may be performed to return to the standard unloader 40. In other words, the unloader 40 of this embodiment can be arbitrarily and alternately switched between the standard unloader and the pneumatic unloader depending on the type of load.

[0069] (5) The unloader 40 of this embodiment can be applied to any application, can be installed in locations other than thermal power plants, and can handle cargo other than coal and biomass fuels.

[0070] The configurations of each embodiment and each variation described above can be combined in part or in whole, as long as there is no particular contradiction. The embodiments of this disclosure are not limited to those described above, but include any variations, applications, and equivalents that are encompassed within the spirit of this disclosure as defined by the claims. Therefore, this disclosure should not be constrained and may be applied to any other art that falls within the scope of the spirit of this disclosure. [Explanation of Symbols]

[0071] 1 vertical tube 2. Vacuum pump 3 horizontal pipe 4 Receiver Tank 14 split vertical tubes 40 consecutive unloaders 43 Boom 47 Bucket Elevator 48 Bucket elevator casing 54 chain 55 buckets 56 Bucket Chain

Claims

1. A continuous unloader that can be switched to a pneumatic unloader, Bucket elevator and, A vertical pipe that can be attached to the bucket elevator, A vacuum pump for supplying negative pressure to the vertical pipe, A continuous unloader characterized by comprising the following features.

2. The boom and A horizontal pipe arranged on the boom and connectable to the vertical pipe, A receiver tank interposed between the horizontal pipe and the vacuum pump, Equipped with The continuous unloader according to claim 1.

3. The bucket elevator comprises a bucket elevator casing, The vertical pipe can be installed inside the bucket elevator casing. The continuous unloader according to claim 1 or 2.

4. The bucket elevator comprises a bucket chain arranged within the bucket elevator casing. The bucket chain comprises a chain and a plurality of buckets detachably attached to the chain. When switching to the pneumatic unloader, the bucket is removed, and the vertical tube is attached to the portion of the chain from which the bucket was removed. The continuous unloader according to claim 3.

5. The aforementioned vertical tube is composed of a plurality of divided vertical tubes that are divided in the longitudinal direction. The continuous unloader according to claim 4.

6. A method for switching the continuous unloader described in claim 5 to the pneumatic unloader, The first step is to remove the bucket from the chain, A second step involves attaching the divided vertical pipe to the portion of the chain from which the bucket has been removed, at a position below the bucket elevator casing. A third step of raising the chain, A fourth step involves attaching another divided vertical pipe to the section of the chain from which the bucket was removed, at a position below the bucket elevator casing, and connecting the other divided vertical pipe to the first divided vertical pipe. A switching method characterized by comprising the following features.

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