Stoker-type combustion device

Abstract

To provide a stoker-type combustion device having a cooling structure of a side fire grate capable of supporting even, operation at an extremely high temperature.SOLUTION: A stoker-type combustion device is provided with at least a pair of side fire grate units 100 arranged on an inner surface of a furnace side wall 10 respectively. The side fire grate units 100 are provided with: a side fire grate 30 facing end faces of fire grates 12, 14, 16; a movable beam 40 which is arranged along a lengthwise direction on a rear surface side of the side fire grate 30 and joined to the side fire grate 30; and an elastic member 60 capable of adjusting a wearing position by operation from outside the furnace side wall 10. The side fire grate 30 is configured to be energized inward via the movable beam 40 and the elastic member 60 and to be freely movable back and forth to the fire grates 12, 14, 16. The movable beam 40 is provided with: a cooling water inlet chamber 76 connected to a cooling water supply pipe 75; and a coolant outlet chamber 78 connected to a cooling water return pipe 77. The coolant outlet chamber 78 communicates with the cooling water inlet chamber 76.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a stoker-type combustion apparatus used for incineration of waste, and more particularly to a horizontal reciprocating stoker-type combustion apparatus that can absorb thermal expansion of the stoker to perform stable combustion. [Background technology]

[0002] A horizontal reciprocating stoker-type combustion system is known as a stoker-type combustion system used for incineration of waste. This horizontal reciprocating stoker-type combustion system has a movable grate and a fixed grate that extend across the furnace side walls. These movable and fixed grates are arranged alternately in a stepped pattern along the direction of waste flow. The movable grate reciprocates relative to the fixed grate, stirring and sending the waste downward while it is burned. In such a stoker-type combustion system, it is necessary to accommodate the thermal expansion of the grate to prevent gaps from forming between the grate and the furnace side walls.

[0003] Therefore, in conventional stoker-type combustion apparatuses, a side grate is arranged on the inner surface of the furnace side wall opposite the grate end face to prevent combustion air from blowing through and wear on the refractory wall, and a movable beam biased by an elastic member is abutted against the inner surface of this side grate (see, for example, Patent Document 1). With this configuration, the side grate can be moved forward and backward relative to the grate in accordance with the thermal expansion of the grate, so that the thermal expansion of the grate is absorbed, and as a result, it is possible to prevent a gap from occurring between the grate and the furnace side wall. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3871484 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, in order to reduce dioxins and achieve high-efficiency heat recovery, the operation of stoker-type combustion equipment has required extremely high temperatures of over 1000°C, and furthermore, the amount of primary combustion air has been reduced, and operation with a lower air ratio has been required. As a result, the temperature inside the combustion furnace has become extremely high, and the flame rating has increased. Child Casting products such as fire grates and side grates may be burnt (high-temperature corrosion and abrasion). In particular, it is known that the tips of fire grates and side grates are rapidly burnt at temperatures above 500°C.

[0006] However, although there have been proposals for cooling structures for fire grates, no effective proposals have yet been made for cooling structures for side fire grates.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a stoker-type combustion apparatus having a cooling structure for the side grates that can be operated at extremely high temperatures. [Means for solving the problem]

[0008] In one aspect, a stoker-type combustion apparatus is provided, which includes at least a pair of side grate units each arranged on the inner surface of a furnace side wall, and a plurality of grates arranged across the pair of side grate units. The side grate units include a side grate facing the end face of the grate, a movable beam arranged on the back side of the side grate along its length and connected to the side grate, and an elastic member whose installation position can be adjusted by operating from outside the furnace side wall. The side grate is biased inward via the movable beam and the elastic member, and is configured to be able to move freely toward and away from the grate. The movable beam includes a cooling water inlet chamber connected to a cooling water supply pipe and a cooling water outlet chamber connected to a cooling water return pipe. The cooling water outlet chamber is in communication with the cooling water inlet chamber.

[0009] In one aspect, the side grate unit further includes at least one cooling water block arranged between the movable beam and the side grate, the cooling water block having at least one cooling water flow path having an inlet communicating with the cooling water inlet chamber and an outlet communicating with the cooling water outlet chamber. In one embodiment, the cooling water block is fixed to the back surface of the side grate using a filler, and the filler is mixed with a material having a thermal conductivity higher than that of the filler. In one embodiment, the cooling water inlet chamber and the cooling water outlet chamber extend along the longitudinal direction of the movable beam over the entire length of the movable beam.

[0010] In one embodiment, the cooling water inlet chamber is disposed below the cooling water outlet chamber. In one embodiment, the stoker-type combustion apparatus further includes a flange for fixing the grate unit to a frame structure of the furnace side wall. In one embodiment, the cooling water supply The cooling water return pipe and the cooling water pipe extend through the flange. supply The gap between the flange and the pipe and the gap between the flange and the cooling water return pipe are each sealed by a sealing member. [Effects of the Invention]

[0011] According to the present invention, thermal expansion of the fire grate in the furnace width direction is absorbed by the elastic force of the elastic members that bias the side grates, and the seal between the fire grate and the side grate is achieved by the side grate being pressed against the end face of the fire grate by the elastic force of the elastic members. Furthermore, the side grate is cooled by cooling water during operation. As a result, the side grate can be operated at extremely high temperatures. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the outline of the overall configuration of a stoker-type combustion apparatus according to one embodiment. [Figure 2] FIG. 2 is a transparent top view schematically showing a side grate unit according to one embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the side grate unit shown in FIG. 2 taken along line AA. [Figure 4] 4 is a cross-sectional view of the side grate unit shown in FIG. 2 taken along line BB. [Figure 5] 5 is a cross-sectional view of the side grate unit shown in FIG. 2 taken along line CC. [Figure 6] FIG. 6 is a transparent top view that schematically shows a side grate unit according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating the overall configuration of a stoker-type combustion system according to one embodiment. As shown in FIG. 1, fixed grates 12 and movable grates 14 are alternately arranged in a stepped pattern along the direction of waste flow within the incinerator, spanning between furnace sidewalls 10. Note that FIG. 1 illustrates only one furnace sidewall 10. An end grate 16 is located at the upstream end of these grates 12 and 14. The fixed grate 12 is fixed to a fixed frame 18, and the movable grate 14 is fixed to a movable frame 26 that reciprocates via wheels 22 and rails 24 in response to the operation of a hydraulic cylinder 20. Furthermore, the fixed grates 12 and movable grates 14 are fitted with scrapers 28 that slide over the top surfaces of the fixed grates 12 or movable grates 14 located below.

[0014] A pair of side grates 30 are arranged at positions facing the end faces of the fixed grate 12, the movable grate 14, and the end grate 16 of the furnace side wall 10, and a seal block 32 is arranged above each side grate 30. In FIG. 1, one side grate 30 and this side Only one seal block 32 located above the grate is shown.

[0015] As a result, as the movable grate 14 reciprocates, the refuse thrown in from a refuse hopper (not shown) is agitated and sent downward in sequence for combustion. At this time, the end faces of the fixed grate 12, movable grate 14, and end grate 16 press against the surface of the side grate 30 to seal this area, and a seal block 32 seals the gap between the side grate 30 and the furnace side wall 10. The side grate 30 is a component included in a side grate unit, which will be described later, and faces the end faces of the grates 12 and 14.

[0016] Fig. 2 is a transparent top view schematically showing a side grate unit according to one embodiment, and Fig. 3 is a cross-sectional view of the side grate unit shown in Fig. 2 taken along line AA. Furthermore, Fig. 4 is a cross-sectional view of the side grate unit shown in Fig. 2 taken along line BB, and Fig. 5 is a cross-sectional view of the side grate unit shown in Fig. 2 taken along line CC.

[0017] The side grate unit 100 shown in Fig. 2 has the above-mentioned side grate 30 and is arranged on the inner surface of the furnace side wall 10 (see Fig. 1). The side grate unit 100 is a unit for cooling the side grate 30 while allowing the side grate 30 to move forward and backward relative to the grates 12 and 14.

[0018] 2 and 3, a bracket 36 having an L-shaped cross section is attached to the inner surface of a support frame 34 supporting the furnace side wall 10, and the side grate 30 is slidably supported on the upper surface of this bracket 36. With this configuration, the grate 12 (14, 16) is supported by the bracket 36 without being hindered from moving due to thermal expansion.

[0019] A movable beam 40 is arranged on the rear side of the side grate 30, extending over almost the entire length of the side grate 30, and at least one cooling block 70 is arranged between the movable beam 40 and the side grate 30. In the illustrated example, the side grate unit 100 has four cooling blocks 70, and the movable beam 40 is connected to the side grate 30 via the cooling blocks 70.

[0020] The cooling block 70 is fixed to the movable beam 40 by welding, for example, and to the back surface of the side grate 30 with a filler (e.g., a heat-resistant adhesive). The filler, such as a heat-resistant adhesive, completely fills the gap between the back surface of the side grate 30, which is a cast product, and the adhesive surface of the cooling block 70, achieving effective heat exchange between the cooling block 70 and the side grate 30. The filler preferably contains a material (e.g., copper powder) uniformly mixed with the filler, the thermal conductivity of which is higher than that of the filler. By mixing such a material into the heat-resistant adhesive at a predetermined ratio, more effective heat exchange between the cooling block 70 and the side grate 30 can be achieved.

[0021] The type of filler is arbitrary as long as it can fix the cooling block 70 to the side grate 30. For example, the filler may be a heat-resistant adhesive or heat-resistant mortar.

[0022] The movable beam 40 is composed of, for example, a main body 42 having an H-shaped cross section, upper and lower cover members 43 and 44 that close the upper and lower openings of the main body 42, and side cover members 45 and 46 that close both end surfaces of the main body 42. In this embodiment, the main body 42 is a so-called H-shaped steel beam. The upper and lower cover members 43 and 44 extend along the entire length of the main body 42 in the longitudinal direction of the main body 42 and are fixed to the main body 42 by welding. The side cover members 45 and 46 are fixed by welding to both end surfaces of the main body 42 whose upper and lower openings are closed by the upper and lower cover members 43 and 44. By closing the upper, lower, left, and right openings of the main body 42 with the cover members 43, 44, 45, and 46, sealed upper and lower spaces are formed inside the movable beam 40. The upper and lower spaces formed in the movable beam 40 function as a cooling water inlet chamber and a cooling water outlet chamber, which will be described later.

[0023] The lower cover member 44 of the movable beam 40 is slidably supported on a support plate 52 connected to the furnace side wall 10 via legs 72. In one embodiment, the support plate 52 may be the bottom plate of the support box 50, which serves both to support and seal the furnace side wall 10. The movable beam 40 is arranged so as to slide easily on the support plate 52 in the furnace width direction.

[0024] Furthermore, the side grate unit 100 has at least one guide pipe 54 extending inside the furnace side wall 10 and a flange 74 for connecting the guide pipe 54 to the frame structures 81 and 82 of the furnace side wall. In this embodiment, the side grate unit 100 has two guide pipes 54. Each guide pipe 54 is fixed to a through hole in the flange 74, and the flange 74 is fixed to the frame structures 81 and 82 of the furnace side wall 10 via fasteners such as bolts. The flange 74 is fixed to the frame structures 81 and 82, thereby fixing the side grate unit 100 to the frame structures 81 and 82 of the furnace side wall 10. By loosening the fasteners, the side grate unit 100 can be pulled out of the furnace.

[0025] A cylindrical piece member 56 fixed to the side of the movable beam 40 is loosely fitted into the incinerator-side end of each guide pipe 54. An adjustment bolt 58 is housed inside each guide pipe 54, with its square pillar-shaped head 58a exposed to the outside. A large-diameter guide portion 58b is formed at the tip of the adjustment bolt 58 and is loosely fitted into the guide pipe 54. Furthermore, a coil spring 60 is fitted between this large-diameter guide portion 58b and the piece member 56 as an elastic member.

[0026] A nut 64 that screws onto the adjustment bolt 58 is fixed to a casing 62 on the outer surface of the furnace side wall 10 via a flange 66. This makes it possible to adjust the mounting position of the coil spring 60 by rotating the adjustment bolt 58 from outside the furnace side wall using, for example, a wrench.

[0027] Here, the movable beam 40 is provided along the longitudinal direction of the side grate 30, spanning substantially the entire length of the side grate 30. Therefore, at least one coil spring 60 presses any position in the longitudinal direction of the movable beam 40 toward the side grate 30, thereby urging (pressing) the side grate 30 toward the grates 12, 14, and 16 in the furnace. Therefore, pressing means such as the guide pipe 54 and the adjustment bolt 58 can be disposed at any position relative to the side grate 30, which makes it possible to adjust the mounting position of the coil spring 60 from outside the furnace side wall 10.

[0028] A gap S is provided between the end face of the side grate 30 and the inner surface of the furnace side wall 10. This gap S functions as an expansion absorption allowance that absorbs movement of the side grate 30 due to thermal expansion of the grate 12 (14, 16). Furthermore, a seal block 32 is provided above this gap S to seal this gap S. The seal block 32 is formed, for example, from a heat-resistant casting.

[0029] The seal block 32 seals the gap S between the side grate 30 and the furnace side wall 10, preventing the infiltration of combustion ash and non-combustible materials through this gap S. This makes it possible to maintain this gap S for a long period of time, and also eliminates the problem of abnormal wear between the side grate 30 and the grate 12 (14, 16). As a result, the replacement cycle of the side grate 30 can be extended.

[0030] In this embodiment, the coil spring 60 is first retracted using the adjustment bolt 58, and in this state, the grates 12, 14, and 16 and the side grate 30 are set in their predetermined positions. Next, the coil spring 60 is advanced using the adjustment bolt 58 to move the side grate 30 toward the grates 12, 14, and 16, and the elastic force of the coil spring 60 presses the surface of the side grate 30 against the end faces of the grates 12, 14, and 16. This procedure prevents gaps from forming between the surface of the side grate 30 and the end faces of the grates 12, 14, and 16 in the initial stage. Next, the seal block 32 is installed to seal the upper part of the gap S between the side grate 30 and the furnace side wall 10. The elastic force of the coil spring 60 can be readjusted after a certain period of operation to check the condition inside the furnace.

[0031] When the stoker-type combustion system is operating, the side grates 30 move back outward against the elastic force of the coil springs 60 in accordance with the thermal expansion of the grates 12 (14, 16) in the furnace width direction. At this time, the thermal expansion of the grates 12 (14, 16) is absorbed by the elastic force of the coil springs 60, and further, the seal between the grates 12 (14, 16) and the side grates 30 is achieved by the side grates 30 being pressed against the end faces of the grates 12 (14, 16) by the elastic force of the coil springs 60.

[0032] In this embodiment, in order to cool the side grate 30, the side grate unit 100 has a cooling block 70 arranged between the side grate 30 and the movable beam 40. Furthermore, the side grate unit 100 further includes a cooling water supply pipe 76 that supplies cooling water to the cooling water inlet chamber 75, which is the above-mentioned lower space formed in the movable beam 40, and a cooling water return pipe 78 through which the cooling water supplied to the movable beam 40 is returned. The cooling water return pipe 78 is connected to the cooling water outlet chamber 77, which is the above-mentioned upper space formed in the movable beam 40.

[0033] Furthermore, the cooling block 70 has at least one cooling water flow path 70a formed therein, the at least one cooling water flow path 70a having an inlet communicating with a cooling water inlet chamber 75 and an outlet communicating with a cooling water outlet chamber 77. The cooling water supplied from the cooling water supply pipe 76 to the cooling water inlet chamber 75 fills the cooling water inlet chamber 75 and flows into the cooling water flow path 70a. The cooling water that has passed through the cooling water flow path 70a flows into the cooling water outlet chamber 77 and fills the cooling water outlet chamber 77. Furthermore, the cooling water water The cooling water flows from the outlet chamber 77 through a cooling water return pipe 78 to the outside of the side grate unit 100. In this embodiment, the cooling water inlet chamber 75 is connected to the cooling water outlet chamber 77 via a cooling water flow path 70a formed in the cooling block 70.

[0034] The cooling block 70, cooled by the cooling water passing through the cooling water flow path 70a, exchanges heat with the side grate 30 that is in contact with the cooling block 70, thereby cooling the side grate 30. This allows the temperature of the side grate 30 during operation to be maintained at 500°C or less, particularly 350°C or less. As a result, damage to the side grate 30 and a shortened lifespan of the side grate 30 due to high temperatures can be prevented.

[0035] In this embodiment, the side grate unit 30 has four cooling blocks 70, and each cooling unit 70 has two cooling water flow paths 70a. However, the number of cooling blocks 70 and the number of cooling water flow paths 70a can be selected arbitrarily as long as the side grate 30 can be cooled to a predetermined temperature or lower (for example, 500°C or lower, particularly 350°C or lower).

[0036] Furthermore, in this embodiment, the cooling water to be supplied to the plurality of cooling blocks 70 is temporarily stored in the cooling water inlet chamber 75, and the cooling water discharged from the plurality of cooling blocks 70 is temporarily cooled. waterThe cooling water is collected in the cooling water inlet chamber 75 and the cooling water outlet chamber 77. That is, the cooling water inlet chamber 75 functions as an inlet buffer for the cooling water supplied to the cooling block 70, and the cooling water outlet chamber 77 functions as an outlet buffer for the cooling water discharged from the cooling block 70. By providing the cooling water inlet chamber 75 and the cooling water outlet chamber 77 that function as buffers, the cooling water can be supplied to each cooling water flow path 70a at an equal flow rate and recovered from each cooling water flow path 70a at an equal flow rate. As a result, the side grate 30 can be cooled uniformly throughout.

[0037] In this embodiment, the cooling water inlet chamber 75 is disposed below the cooling water outlet chamber 77. With this configuration, the cooling water heated to a high temperature by heat exchange with the side grate 30 flows into the cooling water outlet chamber 77 located above the cooling water inlet chamber 75, preventing the cooling water in the cooling water inlet chamber 75 from being heated by the cooling water in the cooling water outlet chamber 77. As a result, the side grate 30 can be effectively cooled.

[0038] 4 and 5, the cooling water supply pipe 76 and the cooling water return pipe 78 extend through the flange 74. Therefore, the side grate unit 100 further includes a seal member (first seal member) 88 that seals the gap between the cooling water supply pipe 76 and the flange 74, and a seal member (second seal member) 89 that seals the gap between the cooling water return pipe 78 and the flange 74. The seal members 88 and 89 prevent exhaust gas generated in the furnace from leaking from the side grate unit 100.

[0039] When the side grate 30 moves forward or backward relative to the furnace side wall 10 in response to thermal expansion of the grate 12 (14, 16), the cooling water supply pipe 76 and the cooling water return pipe 78 move forward or backward relative to the flange 74. Therefore, the first seal member 88 is, for example, a gland packing that seals the gap between the cooling water supply pipe 76 and the flange 74 while allowing the cooling water supply pipe 76 to slide. Similarly, the second seal member 89 is, for example, a gland packing that seals the gap between the cooling water return pipe 78 and the flange 74 while allowing the cooling water return pipe 78 to slide.

[0040] As shown in Fig. 4, the side grate unit 100 may have a flow regulator (e.g., mass flow controller) 90 that can adjust the flow rate of the cooling water in the cooling water supply pipe 76. The flow regulator 90 is, for example, attached to the side grate 30 and controlled based on the measurement value of a thermometer 93 (see Fig. 2) that measures the temperature of the side grate 30 during operation. More specifically, the flow regulator 90 adjusts the flow rate of the cooling water in the cooling water supply pipe 76 so that the temperature of the side grate 30 measured by the thermometer 93 matches a predetermined set temperature.

[0041] Although not shown, the side grate unit 100 may be provided with a thermometer that measures the temperature of the cooling water in the cooling water supply pipe 76 and a thermometer that measures the temperature of the cooling water in the cooling water return pipe 78, instead of the thermometer 93. In this case, the flow rate regulator 90 is controlled based on the difference between the temperature of the cooling water in the cooling water supply pipe 76 and the temperature of the cooling water in the cooling water return pipe 78. In one embodiment, the side grate unit 100 may be provided with only a thermometer that measures the temperature of the cooling water in the cooling water return pipe 78. In this case, the flow rate regulator 90 is controlled based on the temperature of the cooling water in the cooling water return pipe 78.

[0042] 6 is a transparent top view showing a side grate unit according to another embodiment. The configuration of this embodiment that is not particularly described is the same as that of the above-described embodiment, and therefore, redundant description thereof will be omitted.

[0043] The side grate unit 100 of the stoker-type combustion system shown in Figure 6 differs from the above-described embodiment in that the cooling block 70 is omitted. Therefore, in this side grate unit 100, the movable beam 40 is directly connected to the side grate 30. At least one (two in Figure 6) communication hole 96 is formed in the main body 42 of the movable beam 40, which connects the cooling water inlet chamber 75 to the cooling water outlet chamber 77.

[0044] The cooling water that flows into the cooling water inlet chamber 75 from the cooling water supply pipe 76 flows into the cooling water outlet chamber 77 through the communication hole 96, and then passes through the cooling water return pipe 78 and is discharged from the side grate unit 100.

[0045] The movable beam 40, through which cooling water flows, is directly connected to the side grate 30, so that the side grate 30 exchanges heat with the movable beam 40, thereby cooling the side grate 30. The movable beam 40 is fixed to the back surface of the side grate 30 by a heat-resistant adhesive. As described above, the heat-resistant adhesive may contain copper powder. In one embodiment, the heat-resistant adhesive may be heat-resistant mortar.

[0046] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0047] 10 Furnace side wall 12 Fixed grate 14 Movable grate 16 End grate 18 Fixed Frame 20 Hydraulic cylinder 22 wheels 24 Rail 26 Movable Frame 28 Scraper 30 Side grate 32 Seal Block 36 Bracket 40 Movable beam 42 Main Unit 43, 44, 45, 46 Cover member 52 Support Plate 54 Guide tube 56-piece assembly 58 Adjustment bolt 60 Coil spring (elastic member) 64 Nut 70 Cooling Block 70a Cooling water flow path 74 flange 75 Cooling water inlet chamber 76 Cooling water supply piping 77 Cooling water outlet chamber 78 Cooling water return pipe 81,82 Frame structure 88,89 Sealing member 90 Flow regulator 93 Thermometer 96 Communication hole

Claims

1. A stoker-type combustion apparatus comprising at least a pair of side grate units each arranged on the inner surface of a furnace side wall, and a plurality of grates arranged across the pair of side grate units, The side grate unit is A side grate facing the end surface of the grate; A movable beam is arranged on the rear side of the side grate along the length direction and connected to the side grate; an elastic member whose mounting position can be adjusted by operating from the outside of the furnace side wall; At least one cooling water block disposed between the movable beam and the side grate; The side grate is biased inward via the movable beam and the elastic member, and is configured to be able to move forward and backward toward the grate, The movable beam is a cooling water inlet chamber connected to a cooling water supply pipe; a cooling water outlet chamber connected to a cooling water return pipe, the cooling water outlet chamber is in communication with the cooling water inlet chamber, The cooling water block has at least one cooling water flow path having an inlet communicating with the cooling water inlet chamber and an outlet communicating with the cooling water outlet chamber.

2. The cooling water block is fixed to the back surface of the side grate using a filler, 2. The stoker-type combustion apparatus according to claim 1, wherein the filler is mixed with a substance having a thermal conductivity higher than that of the filler.

3. The stoker-type combustion apparatus according to claim 1 or 2, wherein the cooling water inlet chamber and the cooling water outlet chamber extend along the longitudinal direction of the movable beam over the entire length of the movable beam.

4. The stoker-type combustion apparatus according to claim 1 , wherein the cooling water inlet chamber is disposed below the cooling water outlet chamber.

5. 2. The stoker-type combustion apparatus according to claim 1, further comprising a flange for fixing the side grate unit to a frame structure of the furnace side wall.

6. the cooling water supply pipe and the cooling water return pipe extend through the flange; The stoker-type combustion apparatus according to claim 5 , wherein a gap between the flange and the cooling water supply pipe and a gap between the flange and the cooling water return pipe are sealed by sealing members, respectively.

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