Boiler gas seal mechanism and smoke and ash removal device equipped therewith

Abstract

To provide a gas seal mechanism that can seal a through hole of an outer shell wall of a waste heat boiler penetrated by a hit part of a connection shaft connected to a water tube group, and a flue cinder removal device comprising the same.SOLUTION: A gas seal mechanism seals a through hole 2a of an outer shell wall of a boiler penetrated by a tip part of a connection shaft 13A or 13B connected to a water tube group in the boiler, and comprises: a cylindrical casing part 21 provided on a peripheral edge part of the through hole 2a so as to surround the tip part of the connection shaft 13A or 13B; a flexible seal member 22 provided over an entire circumference along an inner wall surface of the casing part 21; a cylindrical sliding contact part 23 located inside the casing 21, and in sliding contact with the seal member 22 over an entire circumference; and a plate-like member 24 connected to an inner wall surface of the sliding contact part 23 over an entire circumference, and provided around the tip part of the connection shaft 13A or 13B.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a gas sealing mechanism for a boiler and a soot removing device equipped with the same, and particularly to vibrating and removing soot adhering to a water pipe group provided in a boiler by a striking means outside the boiler via a connecting shaft connected to the water pipe group, and relates to a gas sealing mechanism for sealing a through hole in the outer wall of the boiler through which the connecting shaft passes and a soot removing device equipped with the same.

Background Art

[0002] In dry copper smelting, refined crude copper for electrolytic refining is produced by subjecting copper concentrate obtained by flotation of raw ore mainly composed of sulfide ore to smelting treatment in a reverberatory furnace, a converter, and a refining furnace in sequence. Specifically, in the reverberatory furnace, copper concentrate with a copper grade of about 20 to 30% as the main raw material, soot, flux adjuster, auxiliary fuel, etc. as auxiliary raw materials are oxidized and melted by oxygen-enriched air, whereby a matte with a copper grade of about 60% is produced and the matte is separated from the slag due to the specific gravity difference. This matte is withdrawn from the reverberatory furnace and transferred to the converter, where it is further oxidized by oxygen-enriched air and then transferred to the refining furnace, where oxygen is removed to produce refined crude copper with a copper grade of about 99%. The anode obtained by casting the refined crude copper thus produced is electrolytically refined to produce electrolytic copper made of pure copper with a copper grade of 99.99% or more.

[0003] As described above, in dry copper smelting, since copper concentrate containing sulfur is oxidized in a high-temperature molten state, high-temperature exhaust gas containing sulfur dioxide gas is discharged from the reverberatory furnace and the converter. Therefore, this exhaust gas is first introduced into a waste heat boiler, and after heat energy is recovered by heat exchange with boiler water flowing inside a water pipe group provided in the waste heat boiler, it is sent to a sulfuric acid production facility as a raw material for sulfuric acid.

[0004] Incidentally, in smelting furnaces such as the self-smelting furnaces and converters mentioned above, some of the raw materials and auxiliary materials charged into the furnace were not processed within the smelting furnace and were discharged as flue gas. Most of this flue gas (also called dust) is recovered by a dust collector downstream of the waste heat boiler and reused as the aforementioned auxiliary materials, but some of it could adhere to the surface of the water tubes in the waste heat boiler, reducing the heat transfer efficiency. Furthermore, since the adhering flue contains corrosive elements such as halogens derived from sulfide ores, if the flue remains attached to the surface of the water tubes as described above, the water tubes could corrode from the surface.

[0005] Therefore, waste heat boilers are generally equipped with a smoke removal device that removes smoke and ash adhering to the surface of water tubes by vibrating them through impact. For example, Patent Document 1 discloses a technique for removing smoke and ash adhering to water tubes by periodically vibrating these water tubes by striking the end of a connecting shaft, which is connected to a plurality of water tube groups arranged in a waste heat boiler, with an air knocker. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2010-139186 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Since the impacting means, such as the air knocker described above, are installed on the outside of the waste heat boiler, the end of the connecting shaft that connects to the water tube group that is struck by the impacting means had to be inserted through a through hole provided in the outer shell wall of the waste heat boiler and protrude to the outside of the waste heat boiler. This through hole is made larger than the connecting shaft so as not to hinder the vibration of the connecting shaft when it is struck by the impacting means, and therefore a gap exists between the through hole and the connecting shaft. To prevent exhaust gas from leaking to the outside through this gap, the peripheral edge of the through hole and the connecting shaft are connected with an expansion joint to seal the gap.

[0008] However, over long periods of repeated vibration, the expansion joints deteriorate due to metal fatigue and other factors, causing cracks to form in the expanded portion, which can lead to exhaust gas leaking to the outside. In such cases, the problem can be addressed by repairing the cracked portion or replacing the expansion joint itself with a new one, but this requires shutting down the operation of the waste heat boiler during this work, which could negatively impact the productivity of copper smelting. The present invention has been made in view of the above circumstances, and aims to provide a gas seal mechanism that can seal through-holes in the outer shell wall of a waste heat boiler through which the impacted portion of a connecting shaft connected to a group of water tubes passes, without using an expansion joint, and a smoke and ash removal device equipped therewith. [Means for solving the problem]

[0009] To achieve the above objective, the gas seal mechanism according to the present invention is connected to a group of water tubes in a boiler. And supported to swing freely A gas seal mechanism for sealing a through-hole in the outer shell wall of a boiler through which the tip of a connecting shaft passes, comprising: a cylindrical casing portion provided on the periphery of the through-hole so as to surround the tip of the connecting shaft; a flexible sealing member provided along the entire circumference of the inner wall surface of the casing portion; a cylindrical sliding contact portion located inside the casing portion and sliding in contact with the sealing member along its entire circumference; and connected along the entire circumference of the inner wall surface of the sliding contact portion. The end face of the connecting shaft is made so that the surface is at the same level. The connecting shaft has a plate-shaped member that is provided around its tip. Furthermore, the sliding contact portion has a length in its central axis direction that is longer than the axial range of motion of the connecting shaft and shorter than the length in its central axis direction that of the casing portion. It is characterized by the following. [Effects of the Invention]

[0010] According to the present invention, through-holes in the boiler shell wall through which connecting shafts, which play a role in transmitting vibrations to the water tube group installed inside the boiler, pass can be sealed without using expansion joints, thus having extremely great industrial value. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic side view of a waste heat boiler to which the ash removal device of the present invention is suitably applied. [Figure 2] Figure 1 is a perspective view of the convection section of a waste heat boiler. [Figure 3] Figure 2 is a longitudinal cross-sectional view of the convection section of the waste heat boiler, cut by a plane perpendicular to the direction of exhaust gas flow. [Figure 4] Figure 3 is a horizontal cross-sectional view of the convection section of the waste heat boiler, cut along line IV-IV. [Figure 5] Figure 3 is a longitudinal cross-sectional view of the convection section of the waste heat boiler, cut along the VV line. [Figure 6] This is a partial cross-sectional view of the gas seal mechanism and surrounding area of ​​a smoke and ash removal device according to an embodiment of the present invention. [Figure 7] Figure 6 is an exploded perspective view of the gas seal mechanism. [Figure 8] This is a side view showing an alternative example of the body to be struck in the smoke and ash removal device of an embodiment of the present invention. [Figure 9] This is a partial cross-sectional view of the expansion joint and surrounding area of ​​a conventional smoke and ash removal device. [Modes for carrying out the invention]

[0012] 1. Waste heat boiler in a copper smelting plant First, a waste heat boiler in a copper smelting plant, in which a smoke and ash removal device equipped with the gas seal mechanism of an embodiment of the present invention is suitably used, will be described with reference to the drawings. In a dry copper smelting plant, copper concentrate obtained by flotation of raw ore mainly consisting of sulfide ore is sequentially smelted in a self-smelting furnace, a converter, and a refining furnace to produce refined crude copper for electrolytic refining.

[0013] Specifically, first, in the self-smelting furnace, copper concentrate introduced from the storage section of the reaction tower along with oxygen-enriched air is oxidized and melted by the heat of the reaction to produce a matte with a copper grade of approximately 60-65%. Then, in the settler located at the bottom of the reaction tower, the matte is separated from the slag, which consists of iron oxide and silica, due to the difference in specific gravity. As a result of the oxidation and melting in the self-smelting furnace, high-temperature exhaust gas containing a high concentration of SO2 is discharged from the uptake located at the top of the settler, on the opposite side from the reaction tower. After the exhaust gas is used to recover waste heat through heat exchange with boiler water in a waste heat boiler, it is sent to the sulfuric acid production facility as a raw material gas for sulfuric acid.

[0014] The matte produced in the above-mentioned self-smelting furnace is removed from the settler while still molten and transferred to the converter. The converter has a structure in which a roughly cylindrical body is installed horizontally so as to be rotatable, and the matte is charged into the furnace opening located in the center of the body along the central axis via a ladle. By blowing oxygen-enriched air into the matte charged into the converter, the iron and sulfur contained in the matte are removed and oxidized, producing crude copper with a copper content of about 98%. This oxidation process generates high-temperature exhaust gas containing SO2, so the exhaust gas discharged from the converter is sent to the sulfuric acid production facility after waste heat is recovered in a waste heat boiler, as in the case of the self-smelting furnace described above.

[0015] The waste heat boiler into which the above exhaust gas is introduced is generally composed of a radiation section that recovers the radiant heat of the high-temperature exhaust gas and a convection section that recovers the convective heat of the low-temperature exhaust gas whose heat has been recovered in the radiation section. In each section, a group of water pipes through which boiler water flows is installed. Figure 1 schematically shows a waste heat boiler that recovers the heat of the exhaust gas discharged from the converter C. As shown by the white arrow, the exhaust gas discharged from the converter C is introduced from the exhaust gas inlet of the waste heat boiler, and heat exchange with the boiler water takes place in the group of water pipes provided inside them while passing through the radiation section 1 and the convection section 2 in this order. After the heat energy of the exhaust gas is recovered, it is discharged from the exhaust gas outlet of the convection section 2.

[0016] Both of these radiation section 1 and convection section 2 are composed of a main body including a substantially rectangular parallelepiped exhaust gas flow-through section and a tapered section located below it, where the distance between the opposing wall surfaces gradually narrows downward. While the exhaust gas passes through the space of this waste heat boiler in one direction, the soot contained in the exhaust gas falls due to gravity and is collected in the above tapered section. The soot collected in this tapered section is discharged from the waste heat boiler through a soot discharge device 3 such as a chain conveyor. The soot recovered in this way is screened as necessary and then charged into the blast furnace or converter.

[0017] The group of water pipes provided inside the above radiation section 1 and convection section 2 is arranged so that the heat energy of the exhaust gas can be efficiently recovered. Specifically, in the radiation section 1 through which the high-temperature exhaust gas passes, there is provided a so-called water pipe wall in which the main body wall is formed by water pipes and fins, or a panel-shaped group of water pipes in a form where a plurality of straight pipes arranged in parallel are joined together by U-shaped pipes between adjacent ones to form one pipe. On the other hand, in the convection section 2 through which the exhaust gas at a lower temperature than the radiation section 1 passes, in addition to the above water pipe wall and panel-shaped group of water pipes, a coiled pipe type group of water pipes is suspended in the exhaust gas passage.

[0018] As mentioned above, the exhaust gas discharged from the self-smelting furnace and converter contains ash, so ash adheres to the surface of the water tube group described above. To remove the ash adhering to the surface of this water tube group by vibrating, a ash removal device is provided in the waste heat boiler. In the following description, a specific example will be given of applying the ash removal device of the embodiment of the present invention to a water tube group consisting of multiple serpentine-type water tubes suspended in the convection section 2 of the waste heat boiler described above.

[0019] 2. A group of serpentine-type water pipes and smoke and ash removal devices connected thereto. As shown in Figure 2, a group of water tubes 10 is provided within the space of the exhaust gas passage, which is a roughly rectangular parallelepiped that serves as the flow path for exhaust gas, in the convection section 2 of the waste heat boiler. Each water tube 10 consists of a single serpentine tube composed of multiple vertically extending straight sections arranged parallel to each other on a vertical plane parallel to the direction of exhaust gas flow indicated by the white arrows, and multiple U-shaped sections that alternately connect the ends of adjacent straight sections vertically. Both ends of the serpentine tube are connected to an inlet header (also called an inlet header) 11 and an outlet header (also called an outlet header) 12 located outside the convection section 2. Although the water tube 10 shown in Figure 2 is exemplified as a serpentine tube that makes five vertical reciprocations, the number of vertical reciprocations is not limited to this.

[0020] The water tube group, consisting of multiple water tubes 10, located inside the convection section 2, is provided in two equal halves: half in the upstream space and half in the downstream space of the convection section 2. In each of these upstream and downstream spaces, as shown in the longitudinal cross-sectional view of Figure 3, which is taken in a cross-section perpendicular to the direction of exhaust gas flow, the water tube group, consisting of multiple water tubes 10, is arranged at equal intervals in the width direction of the convection section 2. Although Figure 3 shows an example in which eight water tubes 10 are arranged at equal pitches, the number of water tubes 10 constituting the water tube group is not limited to this.

[0021] Of the eight water pipes 10 located in the upstream and downstream spaces shown in Figure 3, the four water pipes 10 in the right half, as viewed from the inlet side of the convection section 2, are welded via rectangular plate-shaped pieces 14 to two right-side connecting shafts 13A extending in the width direction of the convection section 2 at two horizontally spaced upper locations. Similarly, the four water pipes 10 in the left half, as viewed from the inlet side of the convection section 2, are welded via rectangular plate-shaped pieces 14 to two left-side connecting shafts 13B extending in the width direction of the convection section 2 at two horizontally spaced upper locations.

[0022] Since each of these connecting shafts 13A and 13B is positioned between adjacent straight pipe sections, it is preferable to use square pipes with a substantially rectangular cross-section. Each of the connecting shafts 13A and 13B is provided with a pair of substantially rectangular plate-shaped protruding pieces 15 at its upper part, and a pair of hinge means 17 hanging down from a suspension beam 16 fixed within the convection section 2 engages with each of these protruding pieces 15.

[0023] While there are no particular limitations on the structure of the hinge mechanism 17 described above, it is preferable that it consists of a suspension rod 17b inserted from below through a vertically penetrating through-hole provided in the suspension beam 16 and fixed at its tip with a nut 17a, as shown within the dotted frame in Figure 5, and a pair of opposing strip-shaped members 17c, each rotatably connected at both ends by pins 17d to the lower end of the suspension rod 17b and the protruding piece 15, respectively. With this configuration, each of the connecting shafts 13A and 13B can be supported so as to swing in its longitudinal direction, and the multiple water pipes 10 connected to each of the connecting shafts 13A and 13B can be vibrated by the striking of the striking means described later.

[0024] Each of the above-mentioned connecting shafts 13A and 13B has one end protruding to the outside through a through hole provided in the outer shell wall of the convection section 2, and a striking body 18 is provided at the tip of this protruding portion. The striking body 18 preferably consists of a cylindrical head portion 18a that is struck by a striking means described later, a cylindrical support portion 18b that supports the head portion 18a so as to be able to reciprocate in the direction of the strike, and an elastic body 18c, such as a disc spring, which is sandwiched between the head portion 18a and the support portion 18b and plays a role in reducing the impact force by elastically deforming when the head portion 18a is struck, and storing the impact energy to sustain the vibration time. The head portion 18a has a reduced diameter at the end that is inserted into the support portion 18b, and the elastic body 18c is fitted onto this reduced diameter portion.

[0025] A striking means 19 is provided at a position opposite to the head portion 18a of the object to be struck 18. Preferably, the striking means 19 is an air knocker, which uses compressed air pressure to forcefully protrude a piston from a cylinder to strike the head portion 18a of the object to be struck 18. However, the striking means 19 is not limited to an air knocker; a hammering device may also be used, which rotates a shaft to which the handle of a hammer is rotatably attached, causing the hammer to swing down by gravity to strike the head portion 18a of the object to be struck 18. As mentioned above, a gap exists between the through-holes provided in the outer shell wall of the convection section 2 through which one end of each of the connecting shafts 13A and 13B passes, and the connecting shafts 13A and 13B. Therefore, a gas seal mechanism 20 is provided to seal this gap.

[0026] As described above, the smoke and ash removal device according to the embodiment of the present invention comprises connecting shafts 13A and 13B connected to a group of water pipes 10, hinge means 17 that pivotably support each of these connecting shafts 13A and 13B, a striking body 18 provided at the tip of these connecting shafts 13A and 13B, striking means 19 that strikes the striking body 18, and a gas seal mechanism 20 that seals the gap of the through-hole in the outer shell wall through which one end of these connecting shafts 13A and 13B passes. Next, the gas seal mechanism 20 constituting the smoke and ash removal device according to this embodiment of the present invention will be described in detail.

[0027] 3. Gas seal mechanism The gas seal mechanism 20 constituting the smoke and ash removal device of the embodiment of the present invention consists of a cylindrical casing portion provided on the periphery of the through-hole in the outer shell wall of the convection section 2 of the waste heat boiler through which the tips of the aforementioned connecting shafts 13A and 13B pass, so as to surround the tips of the connecting shafts; a flexible sealing member provided circumferentially along the inner wall surface of the casing portion; a cylindrical sliding contact portion located inside the casing portion and slidingly contacting the sealing member circumferentially; a plate-shaped member that connects the tips of the connecting shafts to the inside of the sliding contact portion and closes the inside of the sliding contact portion; and a pressing portion that is inserted from the tip side of the casing portion into the gap between the casing portion and the sliding contact portion, and presses the sealing member by sandwiching it between the pressing portion and a projection provided circumferentially on the inner wall surface of the casing portion.

[0028] Referring to Figure 6, the ends of the connecting shafts 13A and 13B, which are responsible for transmitting vibrations to the multiple water tubes 10 mentioned above, protrude outward through through holes 2a provided in the outer shell wall of the convection section 2 of the waste heat boiler. A cylindrical casing section 21 is attached to the periphery of the through holes 2a in the outer shell wall so as to surround the protruding portions of the connecting shafts 13A and 13B. The casing section 21 has flanges at both ends, and the flange located on the through hole 2a side is fillet-welded to the outer shell wall of the convection section 2 over its entire circumference. On the other hand, the flange on the opposite side of the through hole 2a has multiple bolt holes provided at equal intervals in the circumferential direction for inserting bolts for fastening to the flange of the pressing section, which will be described later.

[0029] A rectangular projection 21a is provided around the entire circumference of the inner wall surface of the casing portion 21, and a sealing member 22 abuts against the stepped surface of this projection 21a on the side opposite to the through hole 2a. The type and material of the sealing member 22 are not particularly limited as long as they can properly seal off the leakage of exhaust gas from the waste heat boiler through the gap inside the casing portion 21, but a gland packing with a substantially square cross-section is preferred, and a gland packing made of braided carbon fibers into a string shape is more preferred. A gland packing made of braided carbon fibers is excellent not only in heat resistance and durability, but also in sliding properties with respect to the sliding surface of the sliding contact portion 23 described later, so that the problem of vibration during impact damping up quickly during use can be suppressed.

[0030] The sliding contact portion 23, located inside the casing portion 21, has a cylindrical shape similar in plan view to the casing portion 21 and is provided concentrically with the casing portion 21. This allows the sliding contact surface 23a of the sliding contact portion 23 to slide against the sealing member 22 over its entire circumference. The length L1 of the sliding contact portion 23 in the axial direction is longer than the axial range of motion of the connecting shafts 13A and 13B which can swing by the aforementioned hinge means 17, thereby maintaining the sealed state even when the connecting shafts 13A and 13B swing.

[0031] The plate-shaped member 24, which is provided around the tips of the connecting shafts 13A and 13B, is welded to the inner wall surface of the sliding contact portion 23 above by welding around its entire circumference. That is, the tips of the connecting shafts 13A and 13B are connected to the inner wall surface of the sliding contact portion 23 via the plate-shaped member 24, and the plate-shaped member 24 also plays a role in closing the inside of the sliding contact portion 23. There are no particular limitations on the specific position where the plate-shaped member 24 is connected to the tips of the connecting shafts 13A and 13B, but it is preferable that the end faces of the connecting shafts 13A and 13B and the surface of the plate-shaped member 24 opposite to the through hole 2a side are at approximately the same level (flush). This makes it easy to fix the multiple ribs, which are provided to protrude radially around the support portion 18b of the impacted object 18 attached to the end faces of the connecting shafts 13A and 13B, onto the surface of the plate-shaped member 24. Furthermore, if round pipes or round bars are used instead of square pipes for the connecting shafts 13A and 13B, an annular member is used for the plate-shaped member 24.

[0032] The pressing portion 25, located in the gap between the casing portion 21 and the sliding contact portion 23, has a cylindrical shape similar to the casing portion 21 in plan view. By inserting it concentrically into the casing portion 21, the sealing member 22 is pressed by the tip of the pressing portion 25 and the annular stepped surface of the projection 21a provided on the inner wall surface of the casing portion 21. The end of the pressing portion 25 opposite to the tip inserted into the casing portion 21 is provided with a flange that connects to the flange on the opposite side of the through hole 2a of the casing portion 21.

[0033] In other words, the flange of the pressing portion 25 is provided with bolt holes at positions corresponding to the bolt holes provided in the flange of the casing portion 21. By inserting fastening bolts through these corresponding bolt holes facing each other and tightening them with nuts, the pressing portion 25 can be fixed to the casing portion 21. When the pressing portion 25 is fixed to the casing portion 21 in this manner, the length L2 in the axial direction of the pressing portion 25 is determined so that the sealing member 22 is pressed appropriately in the axial direction of the pressing portion 25.

[0034] When installing the gas seal mechanism with the above structure, as shown in Figure 7, first, a casing portion 21 is fixed to the periphery of the through-hole 2a by welding or the like, so as to surround the ends of the connecting shafts 13A and 13B that protrude from the through-hole 2a of the outer shell wall of the convection section 2 of the waste heat boiler. Then, a flexible sealing member 22 such as a gland packing is inserted inside the casing portion 21, and the projection portion 21a of the casing portion 21 is brought into contact with the stepped surface on the opposite side from the through-hole 2a.

[0035] Next, the pressing part 25 is inserted from the side opposite to the through hole 2a of the casing part 21, and its flange and the flange of the casing part 21 are tightened with bolts and nuts. As a result, the sealing member 22 is crushed in the direction of the central axis of the casing part 21 by the annular end face of the tip of the pressing part 25 and the projection 21a of the casing part 21. Consequently, the sealing member 22 deforms in a direction in which its inner diameter is reduced, and thus makes surface contact with the sliding contact surface 23a of the sliding contact part 23 located on the peripheral edge of the plate-shaped member 24 that has been pre-installed around the tips of the connecting shafts 13A and 13B, thereby sealing the gap between the casing part 21 and the sliding contact part 23.

[0036] Furthermore, the degree of deformation of the sealing member 22 can be adjusted by the amount of tightening between the flange of the casing portion 21 and the flange of the pressing portion 25. For example, by measuring the distance between the opposing flange surfaces of these two flanges with a gap gauge and adjusting the degree of tightening of the bolts and nuts accordingly, the sealing member 22 can be made to adhere appropriately to the sliding surface 23a of the sliding contact portion 23. This makes it possible to effectively seal the gap inside the casing portion 21 without excessively hindering the continuation of vibration of the connecting shafts 13A and 13B.

[0037] The impacted body 18 described above may have an impacted plate detachably attached to the tip of its head portion 18a. For example, as shown in Figure 8, it is preferable to weld a disc-shaped base plate 26 to the tip of the head portion 18a of the impacted body 18, place a disc-shaped impacted plate 27, which has the same shape in plan view, on top of the base plate 26, and fasten them by inserting bolts through bolt holes provided in advance on the periphery and securing them with nuts. The tip of the impacted body 18, which is directly struck by an impacting means 19 such as an air knocker, is prone to deformation and damage early on, which can lead to problems in the effectiveness of dust removal by impact. However, by providing an impacted plate 27 to the tip of the impacted body 18 as described above, the impacted plate 27 can be easily replaced if it deforms or is damaged, thereby stabilizing the effectiveness of dust removal by impact.

[0038] As described above, the gas seal mechanism of the embodiment of the present invention and the smoke removal device equipped therewith can seal through holes provided in the outer shell wall of a waste heat boiler without using expansion joints, thus enabling stable operation of the waste heat boiler over a long period of time. In other words, conventional smoke removal devices used in waste heat boilers, as shown in Figure 9, used expansion joints 30 to seal the above-mentioned through holes 2a. However, when subjected to repeated loads due to vibration over a long period of time, the bellows portion 31, which is the elastically deformable part of the expansion joint 30, gradually hardens due to metal fatigue. As a result, it becomes difficult to make the elastic deformation of the bellows portion 31 follow the axial vibration of the connecting shafts 13A and 13B caused by the striking means 19, and eventually cracks may occur in the bellows portion 31. Furthermore, when the bellows portion 31 hardens due to metal fatigue, it can forcibly dampen the vibrations by itself.

[0039] In contrast, the smoke and ash removal device of the present invention seals through-holes provided in the outer wall of the waste heat boiler using sealing members such as gland packing, and therefore does not have any parts where cracks due to metal fatigue may occur. Furthermore, since phenomena such as metal fatigue that forcibly dampen vibrations are less likely to occur even after long-term use, the axial vibration of the connecting shaft applied by striking means such as an air knocker can be continued without dampening as much as possible, and thus dust adhering to the water tubes can be effectively removed. Thus, by using the smoke and ash removal device of the embodiment of the present invention, vibrations can be transmitted stably and efficiently over a long period of time to multiple water tubes arranged in the waste heat boiler.

[0040] Although the gas seal mechanism of the present invention and a smoke and ash removal device equipped therewith have been described above based on embodiments, the present invention is not limited to the above embodiments, and various modifications and alternatives can be included without departing from the spirit of the invention. For example, the casing portion, the sliding contact portion located inside it, and the pressing portion inserted into the gap between the casing portion and the sliding contact portion are not limited to a cylindrical shape but may be rectangular. In other words, the scope of the present invention extends to the claims and their equivalents. [Explanation of Symbols]

[0041] 1 Radiant part 2 Convection section 2a Through hole 3 Smoke ash evacuation device 10 water tube 11 Entrance Header 12 Exit Header 13A Right-side connecting shaft 13B Left-side connecting shaft 14 Rectangular plate-shaped pieces 15 Projecting piece 16 Suspension beams 17. Hinge mechanism 17a Nut 17b Suspension Rod 17c Strip-shaped member 17d pin 18. The body that was hit 18a Head section 18b Support part 18c elastic body 19. Strike means 20 Gas seal mechanism 21 Casing section 21a Protrusion 22 sealing member 23 Sliding contact part 23a Sliding surface 24 Plate-shaped member 25 Pressing part 26 circuit boards 27 Impact plate 30 Expansion joints 31 Bellows section C converter

Claims

1. A gas seal mechanism for sealing a through-hole in the outer shell wall of a boiler through which the tip of a connecting shaft, which is connected to a group of water tubes inside the boiler and is supported to swing freely, passes, comprising: a cylindrical casing portion provided on the periphery of the through-hole so as to surround the tip of the connecting shaft; a flexible sealing member provided along the entire circumference of the inner wall surface of the casing portion; a cylindrical sliding contact portion located inside the casing portion and slidingly contacting the sealing member along the entire circumference; and a plate-like member provided around the tip of the connecting shaft so as to be at the same level as the end face of the connecting shaft, which is connected along the entire circumference of the inner wall surface of the sliding contact portion. The sliding contact portion is a gas seal mechanism in which its length in the axial direction is longer than the axial range of motion of the connecting shaft and shorter than the length in the axial direction of the casing portion.

2. The gas seal mechanism according to claim 1, further comprising a pressing portion which is inserted into the gap between the casing portion and the sliding contact portion located inside it, thereby sandwiching and pressing the sealing member between itself and a projection provided around the entire circumference of the inner wall surface of the casing portion.

3. The gas seal mechanism according to claim 1 or 2, wherein the sealing member is a gland packing made of carbon fiber.

4. A smoke and ash removal device comprising: a connecting shaft connected to a group of water tubes arranged inside a boiler to transmit vibrations; a striking part attached to the tip of the connecting shaft; striking means for striking the striking part on the outside of the boiler; and a gas seal mechanism according to claim 1 for sealing a through hole in the outer shell wall of the boiler through which the end of the connecting shaft to which the striking part is attached passes.

5. The smoke and ash removal device according to claim 4, wherein the part to be struck comprises a head part that is struck by a striking means, a support part that supports the head part so as to be able to reciprocate in the direction of the striking, an elastic body sandwiched between the head part and the support part and elastically deforms when the head part is struck, and a plate-like body detachably provided on the surface of the head part that is struck.

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