JP2000266243A - High-temperature heat insulating pipe and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a heat spot from generated beforehand by using a restoring type as ceramic fiber, filling an outer tube with a restoring ceramic fiber by compressing, and filling a clearance formed by thermal expansion difference between the outer tube and a liner in using a pipe. SOLUTION: A restoring ceramic fiber 2 is fixed to the inside of an outer tube 3 by an anchor bolt 4. The restoring ceramic fiber 2 is wound around a liner 1. Then, an organic band 5 is wound around the restoring ceramic fiber 2 as a fastening tool, while being compressed. The high-temperature heat insulating pipe of this constitution is so constituted that the organic band 5 as the fastening tool is decomposed, dissolved, or carbonized to have no strength in entering into the first driving so that the compression load acts on the whole restoring ceramic fiber 2. Therefore, the pipe holds this compression state during driving so that a clearance is hardly generated between the liner and the ceramic fiber 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature insulation pipe, and more particularly to a pipe structure through which a high-temperature and high-pressure fluid flows, such as a pipe from a boiler of a PFBC plant to a gas turbine.

[0002]

2. Description of the Related Art High-temperature, high-pressure gas piping, for example, PFBC
The high temperature gas pipe for (pressurized fluidized bed combustion boiler)
It is a pipe for guiding boiler exhaust gas at a high temperature and a high pressure such as 50 ° C. and 9 atg to a gas turbine. As a piping structure capable of withstanding such a high temperature and a high pressure, a method of lowering the temperature of a high-temperature gas with a heat insulating material and giving pressure to an outer pipe outside the heat insulating material is often used. There are two types of heat insulating materials, castable and ceramic fiber. However, castables are susceptible to cracks due to thermal shock, etc. The use of ceramic fibers is more suitable for PFBC, since the turbine may cause rapid wear and blade breakage.

However, when ceramic fibers are used, it is necessary to use a liner for preventing the fiber fibers from being gradually broken (frayed) by a gas flow. It has a structure in which ceramic fibers and outer tubes are arranged in the radial direction. That is, as shown in FIG. 6, a metal liner 1 for preventing the ceramic fibers from fraying and scattering is inwardly in contact with the high-temperature exhaust gas, ceramic fibers 2 on the outer side, and an outer side for applying pressure to the outermost. Tube 3 is located. In the figure, arrows indicate the flow of the hot gas.

[0004] Here, it is structurally characteristic that the temperature of the outer tube 3 is at most about 200 ° C during operation, while the inner liner 1 is directly in contact with the high-temperature exhaust gas, and becomes 850 ° C. The difference is that the amount of thermal expansion of the liner has to be changed, so that the liner portion has to be formed into a sleeve structure. In addition, the liner uses heat-resistant austenitic stainless steel, and the outer tube uses ferritic carbon steel or low-alloy steel for strength and economy that match the operating temperature. This has a larger coefficient of linear expansion than ferrite-based materials, so the problem of the difference in thermal expansion is further increased.

[0005]

The above problem will be described in detail with reference to FIG. Fig. 7 at the beginning of plant production
As shown in (a), there is no gap between the liner 1 and the ceramic fiber 2, but when the first operation is started, the liner 1 becomes large in the radial direction as shown in FIG. Since the outer tube 3 hardly expands while the outer tube 3 expands, the liner 1 relatively
Will be compressed. In the case of a 250 to 350 MW class PFBC for business use, the inner diameter of the high-temperature gas pipe is 1500 mm
And the compression amount (thickness) δ is as large as about 13 to 15 mm. By the way, if the ceramic fiber is maintained in a compressed state at a high temperature in this way, generally, it hardly recovers. This is due to the use of ceramic fibers with poor resilience.

Therefore, when the liner contracts to its original radius at the time of the stop shown in FIG. 1C, a gap 7 of δ is generated between the liner and the ceramic fiber. For this reason, there is a danger that the high-temperature exhaust gas will enter this gap at the time of startup in the next diagram (d) and induce overheating of the outer tube 3. Originally, the thickness of the outer tube is determined based on the allowable stress of 200 ° C., so that the outer tube cannot withstand high temperature and high pressure, and bulges and blows due to the creep phenomenon. Although the circumferential gap and the flow of the intruding gas are not shown in FIG. 7, the gap 7 shown in FIGS. Flows through the outer periphery and forms a passage (a so-called heat spot) that returns to the main flow side of the gas (the position where the high-temperature exhaust gas is mainly flowing). Such a phenomenon is more likely to occur in a bend portion or a teeth portion than in a straight pipe portion, but in any case, such a heat spot becomes a very serious problem for plant operation. An object of the present invention is to provide a piping structure suitable for preventing a heat spot due to a gap between a liner and a ceramic fiber in a high-temperature gas piping, and a method of manufacturing the same.

[0007]

The invention claimed in the present application is as follows. (1) In the outer tube for maintaining the pressure, the ceramic fiber for shutting off the heat of the high temperature gas inside the outer tube, and the liner for preventing the scattering of the ceramic fiber inside the outer tube, the ceramic fiber is used as the ceramic fiber. A high-temperature adiabatic pipe, characterized by using a resilient material and compressing and filling the resilient ceramic fiber into the outer tube so as to fill a gap caused by a difference in thermal expansion between the outer tube and the liner when the pipe is used. (2) The high-temperature insulating pipe according to (1), wherein the restorable ceramic fiber has a restoration rate satisfying the following expression. Restoration ratio> δ / (h1-h2 + δ) (1) δ: Compression amount due to thermal expansion (mm) h1: Original thickness of ceramic fiber (mm) h2: Work thickness of ceramic fiber (mm)

(3) The outer tube has a flange portion, and a ring-shaped support is provided close to the flange portion and perpendicular to the axial direction of the outer tube, and a restorable ceramic fiber is provided on the ring-shaped support. The high-temperature insulated pipe according to (1) or (2), which is compressed. (4) The high-temperature insulation pipe according to (3), wherein one end of the ring-shaped support is fixed to an inner side of the outer tube via a crack propagation preventing fitting. (5) a step of applying the restorable ceramic fiber to the outside of the tubular liner inserted into the outer tube, a step of fastening the liner on which the restorable ceramic fiber is applied with a fastener from an outer periphery thereof and compressing the liner in a radial direction, And a step of inserting a liner having the compressed resilient ceramic fiber into the outer tube, wherein the fastener is thermally decomposed, melted or carbonized when the pipe is used at a high temperature, and the compressed resilient ceramic is compressed. Recovering and filling a gap generated by a difference in thermal expansion between the outer tube and the liner.

(6) A method for producing a high-temperature heat-insulating pipe, comprising a step of previously applying a ceramic fiber inside the outer pipe. (7) The method for producing a high-temperature insulated pipe according to (5) or (6), wherein a restorable ceramic fiber is wound around the outside of the liner, and is wound while being compressed with an organic band as a fastener. (8) The method for producing a high-temperature insulated pipe according to (7), wherein a metal foil is wound around the organic band.

FIG. 1 is a diagram for explaining a model of the principle of the present invention. In the present invention, for example, the original thickness h1 is 25
Outer tube 3 and liner 2 with 0 mm ceramic fiber
The compression work is performed up to a thickness (h2) of 200 mm. The ceramic fiber expands the liner 2 during operation.
If 3 mm is considered, the compression is 63 mm. However, if the restoration rate is 30%, 187 is applied.
From the state of mm, it is possible to return to the position of 63 × 0.3 = 18.9 mm, that is, h3 = 205.9 mm. However, since the liner is actually at a position of 200 mm, the liner stays at that position, and no gap is generated at the time of stopping.

Here, restoration ratio = (thickness of ceramic fiber at restoration-thickness at compression) / (original thickness-thickness at compression). A generalization of the condition in which no gap is generated is given by equation (1). Restoration rate> δ / (h1−h2 + δ) (1) As the ceramic fiber having resilience, heat treatment is performed on alumina-silica fiber at 950 to 1000 ° C., crystallization to mullite, and high temperature. Although the one having the following stability (manufactured by Isolite Industry Co., Ltd., trade name 1260S) is mentioned as a preferable one, the present invention is not limited to this.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method for manufacturing a high-temperature insulation pipe according to the present invention will be described with reference to FIG. (A) First, as a step 1, the restorable ceramic fiber 2 is fixed inside the outer tube 3 with the anchor bolt 4. (B) Next, as step 2, the highly resilient ceramic fiber 2 is wound around the liner 1. (C) Next, as step 3, the organic band 5 is fastened as a fastener while being compressed around the highly restorable ceramic fiber. At this time, the load required to compress the ceramic fiber is about 0.05 kg / cm ² at a compression ratio of 20% (a compression ratio of 20% when a 250 mm one is compressed to 200 mm). Can respond. (D) Next, as step 4, a thin (for example, 0.1 to 0.3 mm) stainless steel foil 6 is wound on the ceramic fiber compressed by the organic band. (E) Finally, as step 5, the liner side is inserted into the outer tube side, and the construction is completed.

[0013]

The high-temperature insulated pipe according to the present invention, when it enters the first operation (usually a trial operation), the fastener (in this case, the organic band) is decomposed, melted or carbonized, and has no strength. Acts on the entire ceramic fiber. Therefore, such a compressed state is maintained during the operation, and the gap between the liner and the ceramic fiber at the time of stop and start as shown in FIG. 7 does not occur.

As the material of the fastener (organic band, bolt, etc.) of the ceramic fiber, a material which has strength at room temperature and loses its strength by thermal decomposition or carbonization at a relatively low temperature (for example, 150 to 200 ° C.) is desirable. For example, those made of a thermoplastic resin such as polyethylene are suitable. Also, as shown in step (c) of FIG. 2, when the stainless steel foil is coated on the ceramic fiber,
This is effective not only for the effect of facilitating insertion into the outer tube, but also for blocking the bypass passage of the high-temperature exhaust gas on the outer tube side.

FIG. 3 is an explanatory view in the case where the present invention is applied to a pipe of a straight pipe portion of a flange type. As a procedure, the pipe of the present invention can be manufactured as follows. (1) As step 1, heat insulation is performed on the outer pipe 3 side. First, an organic bolt 1 is attached to an axial partition 10 as a ring-shaped support which also functions as a member for fixing the liner to the outer tube.
1 is fixed (for example, a hole is formed in the axial partition wall 10 and fixed with a nut), and the disc-shaped high resilience ceramic fiber 2 having a hole at a position corresponding to the bolt is fixed using the bolt. At this time, the bolt is set to a predetermined length, and tightened to a predetermined compression ratio with a nut via a washer. Next, the highly resilient ceramic fiber 2 is fixed to the inside of the outer tube 3 by using a metal anchor bolt 4. At this time, a ceramic fiber having high resilience is desirable, but since the ceramic fiber 2 on the liner side is used with high resilience, it is not always necessary to have high resilience.

(2) As step 2, high resilience ceramic fibers are compressed inside the liner 1 using the organic band 5 until a predetermined compression ratio is reached. Next, a stainless steel foil 6 is wound thereon. (3) In Step 3, the liner-side cylinder produced as described above is inserted into the outer tube-side cylinder. (4) As step 4, the axial partition (ring-shaped support) 10 and the outer tube 3 are welded, and a high-recovery ceramic fiber is fixed to the axial partition on the downstream side in the flange flow direction using an organic bolt. In this way, the highly restorable ceramic fiber can be compressed and applied over the entire flange.

In the embodiment shown in FIG. 3, the ring-shaped support shown as the axial partition 10 has a two-piece structure and is fastened by bolts 15, but may have a one-piece structure. When the ring-shaped support 10 is directly welded to the outer tube 3, a crack may be generated in the weld metal 13. Therefore, the ring-shaped support 10 may be fixed via a crack prevention metal piece 14, for example. In addition,
This ring-shaped support can be generally applied to any high-temperature insulation pipe.

FIG. 4 is an explanatory view showing an embodiment in which the present invention is applied to a pipe at a bend portion. Since the bend pipe has a curvature, it is necessary to divide it into segments (divided into four in FIG. 4) and to perform construction. Means are steps 1 to
Up to 3 is the same as the case of the straight pipe of FIG. 2, but there is no step of coating the stainless steel foil on the ceramic fiber, and as shown in Steps 6 to 9, four divided segments are sequentially constructed. Different in that.

FIG. 5 is an explanatory view showing an embodiment in which the present invention is applied to the piping of the teeth portion. After applying the ceramic fiber 2 to the outer tube 3 in step 1,
In step 2, ceramic fiber 2
In step 3, insert this into the outer tube side, and in step 4, compress the ceramic fiber 2 into the vertical inner tube 1 and insert it into the outer tube 3 in step 5. Thereby, the high restorability ceramic fiber can be compression-constructed over the entire teeth portion. In the figure, arrows indicate the gas flow direction.

The ceramic fibers in the straight pipe portion, the bend portion, and the tees portion shown in FIGS. 3 to 5 are respectively applied to the outer pipe portion with anchor bolts, and then the ceramic fiber is compressed in the liner side. In this method, the ceramic fiber is not applied to the outer tube, but the material compressed and applied to the liner may be inserted directly into the outer tube.

FIG. 8 shows the result of measuring the restoration rate in the range of room temperature to 800 ° C. or more in order to confirm whether the above-mentioned 30% or more is realistic as the restoration property of the ceramic fiber. As the type of fiber, the most frequently used alumina-silica-based fiber was selected from the viewpoints of chemical stability, heat resistance, economy and the like. As a result, it can be seen that when the crystallization heat treatment material is used, a restoration rate of 30% or more is a sufficiently feasible value. In the case where the crystallization heat treatment is not performed, 8
The restoration rate at 00 ° C. or higher was almost zero.

[0022]

According to the present invention, it is possible to prevent the occurrence of a gap due to a difference in thermal expansion between the outer pipe and the liner of a high-temperature gas pipe such as a PFBC plant, and to reduce the risk of generating a heat spot.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a partial cross section of a high-temperature insulation pipe for explaining the principle of the present invention.

FIG. 2 is an explanatory view of a construction procedure of the present invention.

FIG. 3 is an explanatory view in a case where the present invention is applied to a straight pipe portion of a high-temperature insulation pipe having a flange portion.

FIG. 4 is an explanatory diagram when the present invention is applied to a bend unit.

FIG. 5 is an explanatory diagram when the present invention is applied to a teeth portion.

FIG. 6 is a partial cross-sectional view of a conventional high-temperature insulation pipe.

FIG. 7 is an explanatory view showing a problem of the related art.

FIG. 8 is a view showing the relationship (data) between the compression holding temperature of ceramic fibers and the restoration rate.

[Explanation of symbols]

1: liner, 2: ceramic fiber, 3: outer tube, 4: anchor bolt, 5: organic band, 6: stainless steel foil.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideo Mori 6-9 Takara-cho, Kure-shi, Hiroshima Pref. Inside the Kure Factory of Babcock Hitachi, Ltd. (72) Inventor Yu Shida 7-1-1, Omika-cho, Hitachi-shi, Ibaraki Inside Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Ryuji Kurashiki 3-36 Takara-cho, Kure-shi, Hiroshima Prefecture Babcock Hitachi Inside Kure Research Laboratories Co., Ltd. (72) Genroku Nakao 3-36 Takara-cho, Kure-shi, Hiroshima Prefecture Babcock Hitachi Inside Kure Research Institute Co., Ltd. (72) Inventor Yuji Fukuda 3-36 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Inside Kure Research Institute Co., Ltd. (72) Inventor Takanori Katori 6-9 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Kure Factory F term (reference) 3H111 AA01 BA01 BA03 BA09 CA52 CB04 CB05 CB06 CB07 CB14 CB28 CB29 DA15 DB11 EA01

Claims (8)

[Claims] 1. A piping comprising an outer tube for maintaining pressure, a ceramic fiber for shutting off heat of a high-temperature gas inside the outer tube, and a liner for preventing the scattering of the ceramic fiber inside the outer tube. High-temperature insulation pipe characterized in that a resilient fiber is used as the fiber, and the outer pipe is compression-filled with the resilient ceramic fiber so as to fill a gap caused by a difference in thermal expansion between the outer pipe and the liner when the pipe is used. . 2. The high-temperature insulation pipe according to claim 1, wherein the restorable ceramic fiber has a restoration rate satisfying the following expression. Restoration ratio> δ / (h1-h2 + δ) (1) δ: Compression amount due to thermal expansion (mm) h1: Original thickness of ceramic fiber (mm) h2: Work thickness of ceramic fiber (mm) 3. The outer tube has a flange portion, and a ring-shaped support is provided close to the flange portion and perpendicular to the axial direction of the outer tube, and the restorable ceramic fiber is compressed against the ring-shaped support. The high-temperature insulation pipe according to claim 1, wherein the high-temperature insulation pipe is constructed. 4. The high-temperature insulation pipe according to claim 3, wherein one end of the ring-shaped support is fixed to the inner side of the outer tube via a crack propagation preventing fitting. 5. A step of applying a restorable ceramic fiber to the outside of a tubular liner inserted into an outer tube, wherein the liner on which the restorable ceramic fiber is applied is fastened from its outer periphery with a fastener and compressed in a radial direction. And a step of inserting a liner having the compressed resilient ceramic fiber into the outer pipe. When the pipe is used at a high temperature, the fastener is thermally decomposed, melted or carbonized, and the compressed regenerated A method for producing a high-temperature adiabatic pipe, characterized in that conductive ceramics recover and fill a gap created by a difference in thermal expansion between the outer pipe and the liner. 6. A method for producing a high-temperature heat-insulated pipe, comprising a step of previously applying a ceramic fiber inside the outer pipe. 7. The method for producing a high-temperature insulation pipe according to claim 5, wherein a restorable ceramic fiber is wound around the outside of the liner, and then wound while being compressed with an organic band as a fastener. 8. The method according to claim 7, wherein a metal foil is wound around the organic band.