JP2008111059A - Temporary structure of rock fall prevention net in oven and method for temporarily providing the same net - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suggest a temporary structure of rock fall prevention net in an oven, capable of improving safety of workers in an oven by preventing falling of brick or the like releasing from a side wall of the oven. <P>SOLUTION: The method for temporarily providing the rock prevention net is characterized by fixing an upper end opening 12 in a rock fall prevention net 11 constituted in cylindrical state so that openings 12 and 13 are formed at upper and lower ends in an oven 2 in which a diameter-expanding side wall 46 in which the diameter is gradually expanded from an oven port 42 to the lower direction and a vertical side wall 48 installed in nearly vertical direction from the lower end 47 of the diameter-expanding side wall 46 toward an oven bottom 43 are at least formed, over at least 3 places in an oven port 42 formed in the center of oven top in the oven 2, and injecting air in arbitrary height in the vertical side wall 48 into a first air duct 31 provided in a ring-like state along the opening 13 of the lower end of the rock fall prevention net 11, and expanding the diameter of the first air duct 31 to the outside and making the outer periphery in the opening 13 of the lower end of the rock fall prevention net 11 adhere tightly to the vertical side wall 48 thereby. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a cylinder in which at least a diameter-enlarged side wall that is gradually expanded downward from the furnace port and a vertical side wall that is erected in a substantially vertical direction from the lower end of the diameter-enlarged side wall toward the furnace bottom are formed. The present invention relates to a temporary structure for falling rock prevention nets in a furnace and a method that are temporarily provided when repairing a shaped furnace.

  A cylindrical furnace typified by Coke Dry Quenching Equipment (CDQ) is a facility that extinguishes red hot coke that has been carbonized in a coke oven with an inert gas flowing in a cooling tower. Since this CDQ is extinguished in a closed cooling tower, there is an advantage that it is possible to prevent dust scattering which has been regarded as a problem in the conventional wet fire extinguishing method.

Recently, from the viewpoint of expediting furnace repair and effective use of bricks, furnaces that have a structure that allows the repair and replacement of only the furnace bottom are also in widespread use. Various improvements have also been made in the method of repairing the furnace wall (see, for example, Patent Document 1). In particular, in recent years, workers can actually enter the furnace and perform various repair operations. In addition, as shown in FIG. 9, a furnace 7 is also proposed in which an entrance / exit 73 for a worker is formed on a side wall 72 of the furnace bottom 71.
JP 2004-26295 A

  However, when an operator actually enters the furnace and performs various repairs, bricks and attached carbon are peeled off and dropped from the enlarged side wall 74 that is gradually enlarged downward from the furnace opening. . For this reason, in order to further improve the safety of workers working in the furnace, it has been necessary to construct a rock fall prevention structure that focuses particularly on bricks and the like that are peeled off from the enlarged side wall 74.

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is to prevent the falling of bricks and the like peeled off from the side wall of the furnace, thereby preventing the workers in the furnace from falling. The object is to propose a temporary structure and method for preventing falling rocks in a furnace that can improve safety.

  In order to solve the above-described problems, the inventor is provided with a diameter-enlarging side wall that is gradually expanded downward from the furnace port, and a substantially vertical direction from the lower end of the diameter-expanding side wall toward the furnace bottom. For the cylindrical furnace having at least the vertical side wall formed therein, the opening at the upper end of the falling rock prevention net configured in a cylindrical shape so that the openings are formed at the upper and lower ends respectively, The air is injected at an arbitrary height in the vertical side wall into the first air duct that is fixed in at least three places and is provided in a ring shape along the opening at the lower end of the rock fall prevention net. The present invention has invented a rockfall prevention net temporary structure and method in which the outer periphery of the opening at the lower end of the rockfall prevention net is brought into close contact with the vertical side wall by expanding the diameter of the air duct to the outside.

  That is, the falling rock prevention net temporary structure according to the present invention is erected in a substantially vertical direction from the lower end of the diameter-enlarged side wall toward the furnace bottom. In the temporary falling rock prevention net temporary structure in the furnace, which is preliminarily provided when repairing a cylindrical furnace having at least a vertical side wall formed therein, it is configured in a cylindrical shape so that openings are formed at the upper and lower ends, respectively. A rockfall prevention net, a fixing means for fixing the opening at the upper end of the rockfall prevention net in at least three locations at the furnace port, and a ring shape along the opening at the lower end of the rockfall prevention net. An opening at the lower end of the rock fall prevention net by injecting air at an arbitrary height in the vertical side wall and expanding the outside diameter. In The circumferential and characterized by being brought into close contact with the vertical side walls.

  At this time, it further includes a second air duct arranged in a ring shape at an intermediate position from the upper end to the lower end of the rockfall prevention net, and the second air duct is infused with air at the lower end of the enlarged diameter side wall and expands outward. The outer circumference of the intermediate position of the rock fall prevention net may be brought into close contact with the lower end of the enlarged diameter side wall by being diametered.

  Moreover, the rock fall prevention net method according to the present invention includes a diameter-enlarged side wall that is gradually expanded downward from the furnace port, and a vertical line that is disposed in a substantially vertical direction from the lower end of the diameter-enlarged side wall toward the furnace bottom. In the method of temporarily installing a rockfall prevention net in a furnace that is temporarily set when repairing a cylindrical furnace having at least a side wall, a rockfall prevention net configured in a cylindrical shape so that openings are formed at the upper and lower ends, respectively. In the first air duct that is fixed in a ring shape along the opening at the lower end of the rock fall prevention net, the opening at the upper end of the By injecting air at a height and expanding the diameter of the first air duct to the outside, the outer periphery of the opening at the lower end of the rock fall prevention net is brought into close contact with the vertical side wall.

  At this time, air is injected at the lower end of the enlarged side wall into the second air duct that is provided in a ring shape at an intermediate position from the upper end to the lower end of the rock fall prevention net, and the second air duct is expanded outward. Thus, the outer periphery of the intermediate position of the rock fall prevention net may be brought into close contact with the lower end of the expanded side wall.

  Before actually repairing this furnace, by constructing a temporary rockfall prevention net temporary structure constructed as described above, the fallen bricks and adhering carbon on the expanded side wall can be dropped by this rockfall prevention net. It becomes possible to prevent. For this reason, it becomes possible to improve the safety | security of the worker who performs repair work etc. in a furnace bottom.

  Hereinafter, a temporary rockfall prevention net temporary structure to which the present invention is applied will be described in detail with reference to the drawings.

  The falling rock prevention net temporary structure 1 to which the present invention is applied is applied to a cylindrical furnace 2 as shown in FIG.

  The rockfall prevention net temporary structure 1 includes a rockfall prevention net 11, a winch 21 that fixes the opening 12 at the upper end of the rockfall prevention net 11, and a ring shape along the opening at the lower end of the rockfall prevention net 11. The first air duct 31 is provided.

  The furnace 2 is a cylindrical furnace represented by Coke Dry Quenching equipment (CDQ), and extinguishes the red hot coke dry-distilled in the coke oven with an inert gas flowing in the cooling tower. Equipment. In the furnace 2 represented by this CDQ, the fire is extinguished in a closed cooling tower, and therefore, there is an advantage that it is possible to prevent dust scattering which has been regarded as a problem in the conventional wet fire extinguishing method. Incidentally, the furnace 2 may be applied as a so-called vertical tilt furnace.

  The furnace 2 may be designed by covering the inner surface of the iron skin forming the outer surface with permanent bricks, and further building a refractory brick inside thereof. The furnace 2 is formed of a hollow concentric container, and a furnace port 42 that is largely opened at the center of the furnace top 41 is formed at the center. In the furnace 2, the bricks described above are arranged in a spiral shape from the center of the furnace bottom 43 to the furnace top 41. The furnace 2 has an enlarged side wall 46 that gradually expands downward from the furnace port 42, and a vertical side wall 48 that stands in a substantially vertical direction from the lower end 47 of the enlarged side wall 46 toward the furnace bottom 43. Is at least formed. Further, in the furnace 2, an entrance / exit 49 for the worker is formed on the side wall of the furnace bottom 43 so that the worker can actually enter the furnace and perform various repair work.

  The rock fall prevention net 11 is made of, for example, a resin such as PE or a material having excellent heat resistance and strength such as Teflon (registered trademark), and the mesh size is set to be equal to or smaller than the brick size at the maximum. The rock fall prevention net 11 is configured in a cylindrical shape so that an opening 12 is formed at the upper end and an opening 13 is formed at the lower end. That is, the rock fall prevention net 11 is configured to have a substantially ring shape when viewed from a horizontal cross section. Three or more ropes 16 are connected to the opening 12 at the upper end of the rock fall prevention net 11.

  FIG. 2 is a plan view of the furnace 2 including the opening 12 as viewed from above. Four ropes 16 are extended from the opening 12 so that the angle with the other adjacent ropes 16 is approximately 90 °. Each extended rope 16 is connected to a winch 21. The winch 21 makes it possible to wind up the connected ropes 16 respectively. That is, by operating the winch 21, the rope 16 can be wound or the wound rope 16 can be released. In order to allow the winch 21 to be disposed, the fixed beam 5 is formed by crossing the fixed beams 5 so that a substantially square area is formed around the opening 12 as shown in FIG. You may make it arrange | position and arrange | position the beam member 6 spanned further diagonally between these. A winch 21 may be disposed on the beam member 6. Moreover, the number of the ropes 16 should just be three or more, and the winch 21 will be arrange | positioned corresponding to the number of ropes.

  FIG. 3 shows an example in which the winch 21 is disposed on the beam member 6 spanned in an oblique direction. A winch mounting base 22 is attached on the beam member 6, and the winch 21 is attached to the winch mounting base 22. Then, the rope 16 is wound around the winch 21 so that the falling rock prevention net 11 is stretched. When the operator winds up the rope 16, the operator performs this by rotating the handle 23 of the winch 21 in the clockwise direction. When releasing the rope 16, the operator rotates the handle 23 of the winch 21 in the counterclockwise direction. This will be executed by rotating the screen.

  The rope 16 is pulled outward by the winch 21, and accordingly, the upper end portion of the rockfall prevention net 11 is also pulled outward. As a result, the shape of the opening 12 is changed to the furnace port 42. It becomes possible to make it the shape corresponding to the circumference | surroundings.

  The first air duct 31 is attached to the lower end of the rock fall prevention net 11. Any method may be applied as a method of attaching the first air duct 31 to the rockfall prevention net 11. For example, the lower end of the rockfall prevention net 11 has a diameter that allows the first air duct 31 to be inserted. A bag body may be configured, and the first air duct 31 may be inserted into the bag body (not shown). Accordingly, the first air duct 31 can be provided in a ring shape along the opening 13 of the rock fall prevention net 11.

  A hose 32 is connected to the first air duct 31. A compressor 35 is connected to the other end of the connected hose 32. The compressor 35 is normally placed on the ground, and injects air into the first air duct 31 or deaerates from the first air duct 31 based on an operation designated by an operator.

  When air is injected into the first air duct 31, the first air duct 31 is gradually expanded and eventually expanded in diameter. For this reason, for example, when air is injected into the first air duct 31 at an arbitrary height in the vertical side wall 48, the first air duct 31 is expanded in diameter to the outside at the height, and finally the outer periphery of the first air duct 31 is increased. It can be brought into close contact with the vertical side wall. In the example shown in FIG. 1, the case where the outer periphery of the first air duct 31 is brought into close contact with the lower end of the vertical side wall 48 by injecting air into the first air duct 31 at the lower end of the vertical side wall 48 is shown. Since the lower end of the rock fall prevention net 11 is attached to the first air duct 31, the lower end of the rock fall prevention net 11 is in contact with the lower end of the vertical side wall 48.

  As described above, the rockfall prevention net 11 is formed in a cylindrical shape, the opening 12 at the upper end thereof is fixed to at least three places by the winch 21, and the opening 13 at the lower end is provided around the first air duct. The lower end of the vertical side wall 48 is brought into contact with the expansion of the diameter 31. As a result, as shown in FIG. 1, the rock fall prevention net 11 can be stretched in a so-called trumpet shape in which the diameter gradually increases from the upper side to the lower side.

  Before actually repairing the furnace 2, the falling rock prevention net temporary structure 1 having the above-described configuration is temporarily built. As a result, it is possible to prevent the fallen bricks and attached carbon from falling on the diameter-expanded side wall 46 by the falling stone prevention net 11.

  For example, when the brick 19 is peeled off at the expanded side wall 46, the brick 19 falls to the outside of the rock fall prevention net 11 and is guided downward while bouncing. And this brick 19 is guide | induced to the lower end of the vertical side wall 48 with which the lower end of the rock fall prevention net 11 is contacting. The falling rock prevention net 11 is stretched so that the outer periphery of the falling rock prevention net 11 gradually tapers downward toward the vertical side wall 48, so that the brick 19 that has fallen falls between the vertical side wall 48 and the lower end of the falling rock prevention net 11. Will be held between. That is, the first air duct 31 is inflated so as to be in close contact with the vertical side wall 48, and the lower end of the rock fall prevention net 11 is also in close contact with the vertical side wall 48. Can be prevented from falling to the furnace bottom 43. For this reason, it becomes possible to improve the safety | security of the worker who performs repair work etc. in the furnace bottom 43. FIG.

  In addition, you may make it this rock fall prevention net 11 overlap over multiple sheets. As a result, it is possible to more firmly prevent the falling rock prevention net 11 from being broken by a drop impact of the peeled brick or the like.

  In addition, even when bricks or the like have fallen from the vertical side wall 48 as well as the expanded side wall 46, it is possible to prevent them from falling to the furnace bottom 43, thereby further improving work safety. It becomes possible.

  Furthermore, the first air duct 31 and the lower end of the rock fall prevention net 11 described above may be brought into close contact with each other without being limited to the lower end of the vertical side wall 48. In such a case, by operating the winch 21, the height of the lower end of the rock fall prevention net 11 to which the first air duct 31 is attached is raised or lowered to a desired height. Next, by injecting air into the first air duct 31, an operation of bringing the air into close contact at the desired height is performed.

  In addition, this invention is not limited to the structure of the rock fall prevention net temporary structure 1 mentioned above, For example, you may make it actualize as the rock fall prevention net temporary structure 4 as shown in FIG.

  In the rock fall prevention net temporary structure 4, the same components and members as those of the rock fall prevention net temporary structure 1 shown in FIG. 1 described above are denoted by the same reference numerals, and the following description is omitted.

  The rock fall prevention net temporary structure 4 further includes a second air duct 36. The second air duct 36 is provided in a ring shape at an intermediate position from the upper end to the lower end of the rock fall prevention net 4. The second air duct 36 is also connected to the compressor 35 via the hose 39, and air is injected or deaerated based on the operation of the compressor 35. If air is injected when the second air duct 36 is positioned at the lower end 47 of the enlarged diameter side wall 46 as shown in FIG. 4, for example, the second air duct 36 expands at that height and expands outward. Diameter. As a result, the outer periphery of the second air duct 36 can be brought into close contact with the lower end 47 of the enlarged diameter side wall 46. Since the second air duct 36 is attached to the rock fall prevention net 11, the diameter of the second air duct 36 is increased to gradually increase the intermediate position of the fall prevention net 11 to the outside. As shown in FIG. 4, the lower end 47 is in contact.

  That is, the final form of the rock fall prevention net temporary structure 4 is, for example, as shown in FIG. 4, the rock fall prevention net 11 is brought into contact with the lower end of the vertical side wall 48 by expanding the diameter of the first air duct 31. A configuration is adopted in which the falling rock prevention net 11 protrudes in two steps by bringing the falling rock prevention net 4 into contact with the lower end 47 of the enlarged diameter side wall 46 by expanding the diameter of the air duct 36.

  Before actually repairing the furnace 2, the falling rock prevention net temporary structure 4 having the above-described configuration is temporarily built. Thereby, for example, when the brick 20 is peeled off at the expanded side wall 46, the brick 20 falls to the outside of the falling rock prevention net 11 and is guided downward while bouncing. And this brick 20 is guide | induced to the lower end 47 of the enlarged diameter side wall 46 which the intermediate position of the rock fall prevention net 11 is contacting. Since the rock fall prevention net 11 is stretched so that the interval with respect to the enlarged diameter side wall 46 is gradually tapered downward, the fallen brick 20 is positioned between the enlarged diameter side wall 46 and the fall stone prevention net 11. Will be held between. That is, by inflating the second air duct 36, the second air duct 36 is brought into close contact with the lower end 47, and the falling rock prevention net 11 is also brought into close contact with the lower end 47. It is possible to prevent falling. Moreover, in this rock fall prevention net temporary structure 4, since the distance of the enlarged diameter side wall 46 and the rock fall prevention net 11 can be shortened compared with the rock fall prevention net temporary structure 1, the rock fall prevention net 11 of the separated brick 20 is removed. The impact of dropping on the can be suppressed. For this reason, it is possible to prevent the falling rock prevention net 11 from being easily broken.

  Incidentally, it is needless to say that the rock fall prevention net temporary structure 4 may be arranged so as to overlap two or more rock fall prevention nets 11. Further, the height of the second air duct 36 is not limited to the lower end 47 of the diameter-expanded side wall 46, and may be slightly raised or lowered.

  Next, a method for dismantling the temporary falling rock prevention net 11 will be described by taking the falling rock prevention net temporary structure 4 as an example.

  After the repair work in the furnace is completed and the worker goes out from the entrance / exit 49, a lid 52 is provided in the opening 12 at the upper end of the rock fall prevention net 11 as shown in FIGS. If the opening 52 can be closed by providing the opening 52, for example, the lid 52 may be sewn directly to the rock fall prevention net 11.

  Next, the rope 16 is gradually loosened by operating the winch 21. Thereby, the opening part 12 provided with the cover body 52 gradually descends. Then, as shown in FIG. 6, the position of the lid 52 is pushed down to the lower end 47 or less of the enlarged diameter side wall 46. As a result, the brick 20 or the like that is sandwiched between the enlarged-diameter side wall 46 and the intermediate position of the rock fall prevention net 11 rolls over the lid 52 as indicated by an arrow in the figure. .

  In this way, the air in the second air duct 36 is exhausted by operating the compressor 35 with the brick 20 or the like placed on the lid 52. As a result, since the air is extracted from the second air duct 36 that has been filled with air and has expanded, the diameter of the second air duct 36 is gradually reduced inward. Become.

  When the diameter of the second air duct 36 is reduced inward, the adhesion force between the lower end of the diameter-expanded side wall 46 is reduced, and when the second air duct 36 is further deaerated, the second air duct 36 itself becomes the vertical side wall. As shown in FIG. 7, it begins to descend along 48 and falls onto the first air duct 31. Incidentally, the winch 21 is adjusted so that the height of the lid 52 is lower than the second air duct 36 even when the second air duct 36 is lowered downward.

  Next, the air in the first air duct 31 is exhausted. As a result, since the air is extracted from the first air duct 31 that has been filled with air and has been expanded, the diameter of the first air duct 31 is gradually reduced inward. Become. When the diameter of the first air duct 31 is reduced inward, the adhesion between the lower end of the vertical side wall 48 is reduced, and when the first air duct 31 is further deaerated, the first air duct 31 itself starts to descend. As shown in FIG. 8, it falls to the vicinity of the furnace bottom 43. Incidentally, the winch 21 may be adjusted such that the height of the lid 52 is lower than the first air duct 31 even while the first air duct 31 is descending downward. Finally, bricks and the like placed on the lid body 52 that has been lowered to the vicinity of the furnace bottom 43 are carried out through the doorway 49.

  In the method of disassembling the rockfall prevention net 11 executed through the above-described steps, in addition to being able to easily dismantle the rockfall prevention net 11, the bricks 20 and the like that have been peeled off during repair work can be taken out together. It is possible to reduce work labor. Moreover, it can be said that this dismantling method is useful in that the separated brick 20 and the like can be lowered to the vicinity of the furnace bottom 43 extremely safely.

  The method for disassembling the rock fall prevention net 11 described above has been described by taking the rock fall prevention net temporary structure 4 as an example, but the rock fall prevention net temporary structure 1 may also be executed in the same process. In such a case, various operations to be performed on the second air duct 36 are omitted.

  Of course, as another method of disassembling the rock fall prevention net 11, the winch 21 may be adjusted so that the rock fall prevention net 11 is lifted upward from the furnace port 42.

It is a block diagram of the falling rock prevention net temporary structure to which this invention is applied. It is the top view seen from the top of the furnace containing an opening part. It is a figure which shows the example which arrange | positions the winch on the beam member spanned in the diagonal direction. It is a block diagram of the falling rock prevention net temporary structure further provided with the 2nd air duct. It is a figure which shows the example which provides a cover body in the opening part of the upper end of a rock fall prevention net. It is a figure which shows the example which pushed down the position of the cover body to below the lower end of an enlarged diameter side wall. It is a figure which shows the example which the 2nd air duct itself dropped along the vertical side wall, and dropped on the 1st air duct. It is a figure which shows the example which dropped the 1st air duct 31 itself to the furnace bottom vicinity. It is a block diagram of the conventional furnace which formed the entrance and exit for workers in the side wall of the furnace bottom.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Falling rock prevention net temporary structure 2 Furnace 5 Fixed beam 6 Beam member 11 Falling rock prevention net 12, 13 Opening part 16 Rope 19, 20 Brick 21 Winch 22 Winch mounting stand 23 Handle 31 1st air duct 35 Compressor 36 2nd air duct 41 Furnace top 42 Furnace port 43 Furnace bottom 46 Expanded side wall 47 Lower end 48 Vertical side wall 49 Entrance / exit 52 Lid

Claims (9)

A cylindrical furnace in which at least a diameter-enlarged side wall gradually expanding downward from the furnace port and a vertical side wall standing in a substantially vertical direction from the lower end of the diameter-enlarged side wall toward the furnace bottom are formed. In the temporary falling rock prevention net temporary structure in the furnace, which is temporarily set when repairing
A rockfall prevention net configured in a cylindrical shape so that openings are formed at the upper and lower ends, and
Fixing means for fixing the opening at the upper end of the rockfall prevention net over at least three places in the furnace port;
A first air duct arranged in a ring shape along the opening at the lower end of the rockfall prevention net,
The first air duct is formed by injecting air at an arbitrary height in the vertical side wall and expanding the outside diameter so that the outer periphery of the opening at the lower end of the rockfall prevention net is in close contact with the vertical side wall. This is a temporary structure for preventing falling rocks in the furnace. A second air duct arranged in a ring shape at an intermediate position from the upper end to the lower end of the rockfall prevention net;
The second air duct is configured such that the outer periphery of the intermediate position of the rockfall prevention net is brought into close contact with the lower end of the expanded side wall by injecting air at the lower end of the expanded side wall and expanding the outside diameter. The temporary structure for falling rock prevention nets in a furnace according to claim 1, characterized in that: The temporary structure for falling rock prevention nets in a furnace according to claim 1 or 2, wherein the falling rock prevention nets are formed in a cylindrical shape so as to overlap each other. The furnace according to any one of claims 1 to 3, wherein the fixing means is a winch for freely winding a rope connected to an opening at an upper end of the rock fall prevention net. The fallen rock prevention net temporary structure. A cylindrical furnace having at least a diameter-enlarged side wall that is gradually expanded downward from the furnace port and a vertical side wall that is disposed in a substantially vertical direction from the lower end of the diameter-enlarged side wall toward the furnace bottom. In the temporary fall prevention net temporary construction method in the furnace that is temporarily set when repairing,
Fix the opening at the upper end of the rockfall prevention net configured in a cylindrical shape so that openings are formed at the upper and lower ends, respectively, at least three places in the furnace port,
Air is injected at an arbitrary height in the vertical side wall into the first air duct arranged in a ring shape along the opening at the lower end of the rock fall prevention net, and the diameter of the first air duct is expanded outward. By this, the fall prevention net temporary installation method in a furnace characterized by sticking the perimeter in the opening of the lower end of the fall rock prevention net to the vertical side wall. By injecting air at the lower end of the diameter-enlarged side wall into the second air duct arranged in a ring shape at the intermediate position from the upper end to the lower end of the rockfall prevention net, and expanding the diameter of the second air duct to the outside The method according to claim 5, wherein an outer periphery of the intermediate position of the rockfall prevention net is brought into close contact with a lower end of the expanded side wall. After completion of the repair, a lid is provided in the opening at the upper end,
By loosening the fixing of the opening at the upper end of the rockfall prevention net, the position of the lid is pushed downward from the contact position of the vertical side wall at the opening of the lower end of the rockfall prevention net,
6. The method of temporarily installing a rock fall prevention net in a furnace according to claim 5, wherein the lid and the rock fall prevention net are lowered toward the furnace bottom by exhausting air injected into the first air duct. . After completion of the repair, a lid is provided in the opening at the upper end,
By loosening the fixing of the opening at the upper end of the rockfall prevention net, the position of the lid is pushed down to the lower end of the enlarged diameter side wall,
By exhausting the air injected into the second air duct, the falling rock prevention net is gradually lowered together with the lid,
The temporary falling rock prevention net in the furnace according to claim 6, wherein the lid and the falling rock prevention net are lowered toward the bottom of the furnace by exhausting air injected into the first air duct. Method. The method for temporarily installing a rock fall prevention net in a furnace according to any one of claims 5 to 8, wherein the rock fall prevention net is formed in a cylindrical shape by overlapping a plurality of pieces.

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