JP2014173553A - Heat insulation duct for high-temperature gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat insulation duct for high-temperature gas capable of suppressing weld cracks, high-temperature cracks, peeling, or the like while avoiding on-site construction of a heat insulation material.SOLUTION: A heat insulation duct 10 includes a casing 18 that forms a high-temperature gas passage 8. The casing 18 includes: an internal member 32 made of a metal plate that is exposed to the high-temperature gas passage 8; an external member 34 made of a metal plate that is exposed to ambient air; and a flexible heat insulation material 36 interposed between the internal member 32 and the external member 34. The internal member 32 is engaged with the heat insulation material 36 and is coupled to the external member 34 with the insulation material 36 interposed therebetween in a relatively movable manner.

Description

  The present invention relates to a heat insulation duct for high-temperature gas, for example, disposed between a gas turbine and an exhaust heat boiler.

  Since the exhaust gas of the gas turbine is at a high temperature of 500 ° C. or more and is a rotating flow, the exhaust duct of the gas turbine is made of a stainless steel plate or a molybdenum steel plate (SB material), and a heat insulating material is provided outside the plate material. A stretched so-called external heat retaining material is used. In the case of external heat insulation, it is necessary to perform insulation work at the site (installation location). Specifically, in order to retighten the flange of the exhaust duct, leave it in a state where no heat insulating material is applied until the trial run, and after performing the tightening in a state where heat is applied during the trial run and stretch, I do. For this reason, the construction period at the site will be longer, and rust may be generated in the exhaust ducts, bolt holes, etc. while leaving it before the trial run, and it is necessary to take measures to suppress the occurrence of rust. ,It takes time and effort. In addition, although it is a technique regarding a silencer, there is also a technique in which a fiber-based sound absorbing material is attached to a silencer casing, and the surface of the sound absorbing material is covered with a perforated plate or a metal net (for example, Patent Document 1).

Japanese Patent No. 3073420

  Further, for example, in the case of a cogeneration facility, the exhaust gas has a high internal pressure of 0.25 KpaG due to the pressure loss of the exhaust heat boiler, etc. and is a rotating flow at a high temperature, so the exhaust duct on the inlet side of the exhaust heat boiler There is a possibility that the weld will crack. In addition, in operation, in the case of “operations that start and stop every day” and “operations that start and stop every other week”, the exhaust duct material itself deteriorates due to the expansion and contraction load due to heat and the repeated load of residual stress. In addition to the weld, hot cracking may occur. Then, such a weld crack, a high temperature crack, etc. were avoided by giving a castable (refractory material) and a ceramic heat insulating material inside the exhaust duct.

  However, castables are susceptible to vibration and easily cracked, so there is a concern that they will fall off when applied to an exhaust duct of a gas turbine. In addition, the internal heat insulation structure using ceramic heat insulating material is suitable for ducts through which rectified exhaust gas flows, ducts with sufficient internal area and low flow velocity exhaust gas, etc. In addition, in the case of a rotating flow with a flow velocity of around 100 m / s, exhaust gas enters the gap between the stacked tile-shaped plates (plates configured to slide in consideration of thermal elongation) that hold down the ceramic insulation. Therefore, there is a concern that the plate may be deformed and peeled off, or the heat insulating material may be sucked up and scattered.

  This invention was made in view of the said subject, and it aims at providing the heat insulation duct of the high temperature gas which can suppress a weld crack, a high temperature crack, peeling, etc., avoiding construction of a heat insulating material on-site. .

  In order to achieve the above object, the hot gas insulation duct according to the present invention includes a metal plate lining member in which a casing forming a high temperature gas passage is exposed to the high temperature gas passage, and a metal plate outer member. A flexible heat insulating material interposed therebetween, and the lining member is locked to the heat insulating material and connected to the outer surface member via the heat insulating material so as to be relatively movable. Yes.

  According to this configuration, the casing forming the high temperature gas passage has the lining member exposed to the high temperature gas passage, the outer lining member exposed to the outside air, and the flexible heat insulating material interposed therebetween. Since it is constituted by so-called internal heat insulation, it is possible to construct the heat insulating material at the factory, and it is not necessary to install the heat insulating material and prevent rust on site. Moreover, since it is not necessary to apply a refractory material or a heat insulating material to the inside of the casing, they will not fall off or peel off. Further, since the outer member constituting the outer shell of the heat retaining duct is not exposed to the high temperature gas, it is possible to suppress the deterioration of the flange portion and the seal portion provided in the outer member and the occurrence of the hot crack. Moreover, since the outer member is not exposed to the high temperature gas, it is not necessary to use an expensive heat-resistant metal such as a stainless steel plate or a molybdenum steel steel plate, and the heat insulation duct can be manufactured at a low cost as a whole. Furthermore, since the lining member is locked to the heat insulating material and connected to the outer lining member through the heat insulating material so as to be relatively movable, the thermal stress generated in the lining member can be suppressed, and the portion that contacts the high temperature gas Furthermore, the occurrence of weld cracks can be suppressed by eliminating the weld.

  In this invention, it is preferable that the locking piece which protrudes outside and is locked to the end surface of the said heat insulating material is provided in the edge part of the said lining member. According to this configuration, the lining member can be connected to the outer lining member so as to be relatively movable without providing a weld portion with a simple structure.

  When provided with a locking piece, the inner part of the locking piece of the lining member has a superposed part that is bent and superposed, and the outer part of the locking piece is fixed to the outer member. preferable. According to this configuration, the thermal elongation of the lining member can be absorbed by the deformation of the overlapping portion.

  In the present invention, the casing has a flat upper wall, a lower wall, and a pair of side walls connected to form the high-temperature gas passage having a rectangular cross section, and the lining member is formed on each of the walls. It is preferable to be connected to the outer member through a material so as to be relatively movable. According to this structure, since each said wall is flat form, manufacture becomes easy.

  When the casing forms a hot gas passage having a rectangular cross section, an inner portion of the locking piece of the lining member has a superposed portion that is bent and superposed, and the superposition is provided in a gap between adjacent walls. It is preferable that the part and the heat insulation buffer material located in the outer side are arrange | positioned. According to this configuration, the overlapping portion absorbs the deformation of the lining member, and the heat insulating cushioning material absorbs thermal expansion between the walls and blocks heat transfer.

  When the heat insulating cushioning material is provided, it is preferable to include a pressing member that is elastically fitted into the gap inside the heat insulating cushioning material and blocks the high-temperature gas and restricts the position of the heat insulating cushioning material. According to this configuration, the pressing member can prevent the hot gas from directly hitting the heat-insulating buffer material and causing damage, and can hold the heat-insulating buffer material in an appropriate position.

  In the present invention, it is preferable that the lining member is fastened to the outer lining member at an intermediate portion between opposing end portions. According to this structure, the fastening to the inner side of the lining member due to thermal expansion can be effectively suppressed by fastening at the intermediate portion. Moreover, heat transfer to the outer member via the fastening member can be minimized by setting the fastening portion to one place in the intermediate portion. Furthermore, this fastening can prevent the lining member from being greatly deformed inward by the thickness of the heat insulating material on the upper wall serving as the ceiling, or preventing the heat insulating material from shifting and moving downward.

  According to the hot gas insulation duct of the present invention, since the casing forming the high temperature gas passage is constituted by internal heat insulation, it is possible to perform the construction of the heat insulating material at the factory, the construction of the heat insulating material at the site and the rust. No countermeasure is required. In addition, since the outer member is not exposed to the high temperature gas, it is possible to suppress the deterioration of the flange portion, the seal portion, etc. provided on the outer member and the occurrence of hot cracking, and it is not necessary to use an expensive heat resistant metal. As a whole, the heat insulation duct can be manufactured at low cost. Furthermore, since the lining member is connected to the outer lining member through a heat insulating material so as to be relatively movable, the thermal stress generated in the lining member can be suppressed, and a welded portion is eliminated at a location in contact with the high temperature gas. Generation of weld cracks can be suppressed.

It is a schematic structure figure showing a gas turbine system provided with a heat insulation duct of hot gas concerning a 1st embodiment of the present invention. It is a side view of the heat insulation duct. It is a longitudinal cross-sectional view of the heat insulation duct. It is the IV-IV sectional view taken on the line of FIG. It is sectional drawing which expands and shows the edge part vicinity of the upper wall of the casing of FIG. It is sectional drawing which expands and shows the VI section of FIG. FIG. 7 is a VII-VII line view of FIG. 2. It is sectional drawing which expands and shows the VIII part of FIG. It is sectional drawing which expands and shows the IX part of FIG.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a cogeneration system using a gas turbine. In this system, generated power is obtained by rotating the rotor of the generator G through the reduction gear R / G by the driving force of the gas turbine GT. The gas turbine GT includes a compressor 2, a combustor 4, and a turbine 6. An exhaust gas E discharged from the gas turbine GT is discharged to the outside through a high-temperature gas passage 8 that is an exhaust passage.

  Specifically, a heat insulation duct 10 for high-temperature gas constituting a part of the high-temperature gas passage 8 is connected to an exhaust gas outlet of the gas turbine GT, and an exhaust heat boiler 12 is connected to the downstream side of the heat insulation duct 10. An economizer 14 is connected to the downstream side. The water supplied to the economizer 14 is preheated by the exhaust gas E, supplied to the exhaust heat boiler 12 and vaporized. The steam from the exhaust heat boiler 12 is used, for example, as an absorption refrigerator or a heat source for generating hot water. The exhaust gas G that has been heat-recovered through the exhaust heat boiler 12 and the economizer 14 is released to the atmosphere through the exhaust duct 16.

  As shown in FIG. 2, the high temperature insulation duct 10 has a casing 18 that forms a part of the high temperature gas passage 8. As shown in FIG. 4, the casing 18 is formed by connecting a flat upper wall 20, a lower wall 22, and a pair of side walls 24, 24 to form a hot gas passage 8 having a rectangular cross section.

  As shown in FIG. 3, the passage area of the hot gas passage 8 in the casing 18 increases toward the downstream. A cylindrical inlet pipe 26 is connected to the upstream end of the casing 18 by welding, and a flange-shaped first flange 28 is fixed to the upstream end of the inlet pipe 26 by welding. A plurality of bolt insertion holes (not shown) are formed in the first flange 28 side by side in the circumferential direction.

  A flange-like second flange 30 is fixed to the downstream end of the casing 18 by welding. A plurality of bolt insertion holes (not shown) are formed in the second flange 30 side by side in the circumferential direction. The first flange 28 is connected to the exhaust gas outlet of the gas turbine GT shown in FIG. 2 and the second flange 30 is connected to the inlet of the boiler 14 using bolts (not shown).

  As shown in FIG. 4, in each of the walls 20, 22, and 24, the casing 18 includes a metal plate lining member 32 exposed to the high temperature gas passage 8, a metal plate lining member 34 exposed to the outside air, and a space therebetween. And a flexible heat insulating material 36 interposed therebetween.

  The lining member 32 is made of a metal having high heat resistance such as a stainless steel plate or a molybdenum steel plate, and is made of SUS304 having a thickness of 2 mm in this embodiment. The outer member 34 is made of an inexpensive general structural steel material, and in this embodiment is made of SS400 having a thickness of 6 mm. A rust preventive paint is applied to the outer surface of the outer member 34.

  As shown in FIG. 5, the heat insulating material 36 includes an innermost first heat insulating layer 38, an outer second heat insulating layer 40, and an outermost third heat insulating layer 42 on the outer side. In this embodiment, ceramic wool having high heat insulating properties is used for the first heat insulating layer 38, and inexpensive rock wool is used for the second heat insulating layer 40 and the third heat insulating layer 42. Thus, by making the heat insulating material 36 into a multilayer structure, a heat insulating material having high heat insulating properties can be arranged on the inner side that becomes high temperature, and an inexpensive heat insulating material can be arranged on the outer side having a relatively low temperature, so that heat insulation can be effectively performed. At the same time, the cost of the heat insulating material can be reduced as a whole. The heat insulating material 36 may be two layers, four layers or more, or may be a single layer.

  Locking pieces 44 projecting outward are formed at the end portions 32a forming the four sides of the lining member 32. By locking the locking pieces 44 to the end surface 36a of the heat insulating material 36, the lining member 32 is The outer member 34 is connected to the outer member 34 via the heat insulating material 36 so as to be relatively movable in a parallel direction. The outer end 44a of the locking piece 44 is fixed to the outer member 34 by welding.

  The locking piece 44 has a superposed part 50 in which a steel plate is bent and superposed. Specifically, the end portion 32a of the lining member 32 is folded outward and then folded inward, and further folded outward to form a triple overlapping portion 50. The leading end of the overlapping portion 50 extends outward. Thus, a locking piece 44 is formed. Thereby, as shown by a two-dot chain line, even when the lining member 32 is thermally stretched, it is deformed so that the overlapping portion 50 is opened and the thermal elongation is absorbed.

  As shown in FIG. 4, the lining member 32 is fastened to the outer lining member 34 by a fastening member 52 at an intermediate portion 32 b between the opposing end portions 32 a and 32 a. Specifically, as shown in FIG. 6, an opening 54 is formed in the intermediate portion 32 b of the lining member 32, and the entire headless head whose outer end is fixed to the lining member 34 by welding W is formed in this opening 54. A screw bolt 58 is inserted. In the state where the contact plates 56 and 56 are in contact with the inner side and the outer side of the lining member 32 so as to cover the inner end portion of the full screw bolt 58, the inner end portion of the full screw bolt 58 is passed through, The nuts 60 and 60 are screwed together from the inside and the outside, and the lining member 32 is held between the contact plates 56 and 56 by the fastening force of the nuts 60 and 60.

  Thereby, the lining member 32 is fastened to the outer lining member 34 via the full screw bolt 58 and the nuts 60 and 60. That is, the full screw bolt 58 and the two nuts 60, 60 constitute the fastening member 52.

  FIG. 7 shows a connecting portion between the lower wall 22 and the side wall 24. The upper surface 22a of the lower wall 22 and the lower end surface 24a of the side wall 24 are opposed to each other via the first gap S1. An extension 64 extending downward is formed on the outer member 34 of the side wall 24. The extension portion 64 extends outwardly from the outer end surface 22b of the lower wall 22 and is connected to the outer member 34 of the lower wall 22 by welding. This connecting portion is reinforced by welding of the reinforcing plate 66. A second gap S2 is formed between the extension portion 64 and the outer end surface 22b of the lower wall 22, and the second gap S2 communicates with the first gap S1.

  The overlapping portion 50 of the side wall 24 is disposed in the first gap S1, and the overlapping portion 50 of the lower wall 22 is disposed in the second gap S2. Further, the heat insulating cushioning material 68 is disposed on the entire second gap S2 and on the outer side (right side in FIG. 7) of the overlapping portion 50 of the side wall 24 in the first gap S1. The heat insulating cushioning material 68 is, for example, a ceramic blanket.

  A pressing member 70 is disposed inside the heat insulating cushioning material 68 outside the overlapping portion 50 of the side wall 24 in the first gap S1. The holding member 70 is configured by bending a spring steel plate into a V shape. The holding member 70 is elastically fitted inside the heat insulating cushioning material 68 in the first gap S1 to block the high temperature gas from directly hitting the heat insulating cushioning material 68 and to regulate the position of the heat insulating cushioning material 68. Yes. The holding member 70 is prevented from coming out into the high temperature gas passage 8 by the overlapping portion 50 of the side wall 24.

  Although FIG. 7 shows the connecting portion between the lower wall 22 and the side wall 24, the connecting portion between other adjacent walls has the same structure. Thus, the casing 18 has a structure in which the lining member 32 and the outer lining member 34 do not come into contact with each other over a wide area. As a result, the temperature of the exhaust gas E exceeds 550 ° C. in the high temperature gas passage 8, but the surface temperature of the outer member 34 exposed to the outside air is kept below 70 ° C.

  FIG. 8 shows a connecting portion between the lower wall 22 of the casing 18 and the inlet pipe 26. Similarly to the casing 18, the inlet pipe 26 also includes a lining member 72, an lining member 74, and a heat insulating material 76 having a three-layer structure. At both ends of the lining member 72, annular locking members 69 are connected. The first flange 28 is fixed to the upstream end 74a of the outer member 74 of the inlet pipe 26 by welding. The first flange 28 and the locking member 69 are not in contact with each other. A flange-shaped protrusion 78 is fixed by welding on the slightly upstream side of the intermediate portion on the outer peripheral surface of the outer member 74 by welding.

  The upstream end surface 22c of the lower wall 22 of the casing 18 and the downstream end surface 26a of the inlet pipe 26 are opposed to each other via the third gap S3. An extension 80 extending upstream is formed on the outer member 34 of the lower wall 22, and this extension 80 is fixed to the protrusion 78 of the outer member 74 of the inlet pipe 26 by welding. .

  In the third gap S3, the overlapping portion 50 of the lower wall 22 is disposed, and further, the above-described heat insulating cushioning material 68 is disposed on the outside thereof. Further, the pressing member 70 described above is disposed inside the heat insulating cushioning material 68 outside the overlapping portion 50 of the lower wall 22 in the third gap S3. A reinforcing member 82 is fixed by welding at a position corresponding to the third gap S3 on the outer peripheral surface of the outer member 34 of the lower wall 22. FIG. 8 shows a connecting portion between the lower wall 22 and the inlet pipe 26, but the connecting portions between the other walls 20 and 24 and the inlet pipe 26 have the same structure.

  FIG. 9 shows a connecting portion between the upper wall 20 of the casing 18 and the inlet of the exhaust heat boiler 12. The second flange 30 is fixed to the downstream end portion of the outer member 34 of the upper wall 20 by welding, and the outer side thereof is reinforced by a reinforcing member 84. The second flange 30 and the lining member 32 are not in contact with each other.

  The upstream end surface 20a of the upper wall 20 and the upstream end surface 12a of the inlet of the exhaust heat boiler 12 are opposed to each other through the fourth gap S4. In the fourth gap S4, the overlapping portion 50 of the upper wall 20 is disposed, and further, the above-described heat insulating cushioning material 68 is disposed outside thereof. Further, the pressing member 70 described above is disposed inside the heat insulating cushioning material 68 outside the overlapping portion 50 of the upper wall 20 in the fourth gap S4.

  FIG. 9 shows the connecting portion between the upper wall 20 and the inlet of the exhaust heat boiler 12, but the connecting portion between the other walls 22, 24 and the inlet of the exhaust heat boiler 12 has the same structure. Yes. Thus, the first and second flanges 28 and 30 are welded to the low temperature outer members 74 and 34, and the first and second flanges 28 and 30 and the high temperature liner members 72, 32 and Between the hot gas passage 8, heat insulating materials 76 and 36 and a heat insulating buffer material 68 are interposed. Moreover, the lining members 72 and 32 which become high temperature do not have a welding part. That is, the lining members 32 and 72 are members specialized for heat resistance from high-temperature gas, and the lining members 34 and 74 are members for ensuring the strength of the duct.

  In the above configuration, the casing 18 forming the high-temperature gas passage 8 shown in FIG. 4 is constituted by so-called internal heat insulation having a lining member 32, an outer lining member 34, and a heat insulating material 36 interposed therebetween. Therefore, the construction of the heat insulating material 36 can be performed at the factory, and the construction of the heat insulating material 32 on site is not necessary. As a result, there is no variation in the construction level due to the difference in the skills of field workers, and the quality of the heat insulation duct 10 is ensured. Moreover, since it is no longer left on site before the trial operation, it is possible to suppress the occurrence of rust in the bolt holes. Furthermore, since it is not necessary to apply a refractory material or a heat insulating material to the inside of the casing 18, they will not fall off or peel off.

  Furthermore, since the outer member 34 is not exposed to the high-temperature gas, deterioration of the first and second flange portions 28 and 30 and the seal member can be suppressed. Moreover, since the outer member 34 is not exposed to the high-temperature gas, it is not necessary to use an expensive heat-resistant metal such as a stainless steel plate or a molybdenum steel plate for the outer member 34, and the heat retaining duct 10 can be manufactured at a low cost as a whole. Further, since the lining member 32 is locked to the heat insulating material 36 and connected to the outer lining member 34 via the heat insulating material 36 so as to be relatively movable, the thermal stress generated in the lining member 32 can be suppressed, It is possible to suppress the occurrence of weld cracks by eliminating the welded portion at the location in contact with the high temperature gas.

  A locking piece 44 is provided at an end portion 32 a of the lining member 32 shown in FIG. 5, and the overlapping piece 50 is formed by bending the locking piece 44, and an outer portion of the locking piece 44 is an outer member 34. It is fixed to. Thereby, it is possible to connect the lining member 32 to the outer lining member 34 via the heat insulating material 36 so as to be relatively movable without providing a welded portion with a simple structure. Moreover, by providing the overlapping portion 50, the thermal elongation of the lining member 32 can be absorbed. Moreover, since each wall 20,22,24 of the casing 18 is flat form, manufacture becomes easy.

As shown in FIG. 7, since the overlapping portion 50 and the heat insulating cushioning material 68 located outside the first gap S <b> 1 between the adjacent walls 20, 22, 24 in the casing 18 are arranged,
The overlapping portion 50 absorbs the deformation of the lining member 32, and the heat insulating cushioning material 68 absorbs thermal expansion between the walls 20, 22, and 24 and blocks heat transfer.

  Furthermore, since the pressing member 70 is fitted inside the heat insulating cushioning material 68 outside the overlapping portion 50 in the first gap S1, it is possible to realize blocking of high-temperature gas and position regulation of the heat insulating cushioning material 68.

  Since the lining member 32 of FIG. 4 is fastened to the outer lining member 34 at the intermediate portion 32b between the opposing end portions 32a and 32a, the bulging inward of the lining member 32 due to thermal expansion can be effectively suppressed. Moreover, heat transfer to the outer member 34 via the fastening member 52 can be minimized by setting the fastening portion to one portion of the intermediate portion 32b. Further, by this fastening, the lining member 32 may be greatly deformed inward by the thickness of the heat insulating material 36 of the upper wall 20 serving as the ceiling, or the heat insulating material 36 may be shifted and moved obliquely downward (right side in FIG. 2). Can be prevented.

  The present invention is not limited to the above-described embodiment, and various additions, modifications, or deletions can be made without departing from the gist of the present invention. For example, in the above embodiment, the lining member 32 is connected to the outer lining member 34 via the heat insulating material 36 in each of the walls 20, 22, and 24 so as to be relatively movable. In one case, the lining member 32 may be connected to the outer lining member 34 through the heat insulating material 36 so as to be relatively movable. Therefore, such a thing is also included in the scope of the present invention.

8 Hot gas passage 10 Thermal insulation duct 18 Casing 20 Upper wall 22 Lower wall 24 Side wall 32 Inner member 34 Outer member 36 Insulating material 36a End surface 44 of insulating material 50 Locking piece 50 Superposition part 68 Insulating buffer material 70 Holding member S1 First Gap (gap between adjacent walls)

Claims (7)

The casing forming the high temperature gas passage has a metal plate lining member exposed in the high temperature gas passage, a metal plate lining member, and a flexible heat insulating material interposed therebetween.
A high temperature gas heat insulation duct in which the lining member is locked to the heat insulating material and is connected to the outer lining member through the heat insulating material so as to be relatively movable.   2. The hot gas heat insulation duct according to claim 1, wherein an engagement piece that protrudes outward and is engaged with an end surface of the heat insulating material is provided at an end portion of the lining member.   The heat insulation duct for high-temperature gas according to claim 2, wherein an inner portion of the locking piece of the lining member has a superposed portion that is bent and overlapped, and an outer portion of the locking piece is formed on the outer lining member. Fixed hot gas insulation duct. The high temperature gas heat insulation duct according to any one of claims 1 to 3, wherein the casing has a flat upper wall, a lower wall, and a pair of side walls connected to each other to form the hot gas passage having a rectangular cross section. Formed,
A heat insulation duct for high-temperature gas in which the lining member is connected to the outer lining member via the heat insulating material so as to be relatively movable in each wall. The heat insulation duct for high-temperature gas according to claim 4, wherein an inner portion of the locking piece of the lining member has a superposed portion that is bent and superposed.
A heat-insulating duct for high-temperature gas, in which the overlapping portion and a heat-insulating buffer material located outside the overlapping portion are arranged in a gap between adjacent walls.   The heat insulation duct for high-temperature gas according to claim 5, further comprising a pressing member that is elastically fitted into the gap inside the heat-insulating buffer material and blocks the high-temperature gas and restricts the position of the heat-insulating buffer material. High temperature gas insulation duct.   The hot gas insulation duct according to any one of claims 1 to 6, wherein the lining member is fastened to the outer member at an intermediate portion between opposing ends.

Images