JP2011122808A - Exhaust heat recovery boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery boiler which prevents the short pass of a hot gas between a duct and a baffle, without generating abnormal stress due to the thermal expansion of a structure in operating the boiler. <P>SOLUTION: This exhaust heat recovery boiler includes the duct 2 in which the hot gas flows, the baffle 7 disposed inside the duct 2, a plurality of heat transfer tubes 5 disposed inside the baffle 7, and a short pass prevention plate 11 and a gas seal plate 12 disposed in a space 20 between the duct 2 and the baffle 7 for blocking the hot gas short-passing through the space 20. The short pass prevention plate 11 is projected from one of the duct 2 and the baffle 7 toward the other while forming a clearance gap with the other, and the gas seal plate 12 has a fixed end at one end and a free end at the other end, and is curved to be projected to the downstream side in the hot gas flowing direction between the fixed end and the free end to block the clearance gap. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust heat recovery boiler that recovers exhaust heat by flowing a hot gas between a plurality of heat transfer tubes disposed in a duct.

2. Description of the Related Art Conventionally, exhaust heat recovery boilers that recover exhaust heat from hot gas generated in a gas turbine or a furnace are widely known. The exhaust heat recovery boiler has a configuration in which a plurality of heat transfer tubes are disposed in a duct through which hot gas flows, and heat exchange between a fluid such as water or steam flowing in the heat transfer tubes and the hot gas is performed. Is generated.
In such an exhaust heat recovery boiler, the flow path resistance is smaller in the vicinity of the inner wall of the duct where no heat transfer tube is installed than in the heat transfer tube group, so that the hot gas may flow through the short path through this. If the flow rate of the hot gas passing through the short path is large, the flow rate of the gas flowing through the heat transfer tube group is lowered and the heat exchange performance is lowered.

Therefore, as shown in FIG. 10, an exhaust heat recovery boiler equipped with a short path prevention means has been proposed and put into practical use. This exhaust heat recovery boiler includes a duct 51 through which hot gas flows, a baffle 52 disposed along the inner surface of the duct 51 inside the duct 51, a heat transfer tube group 53 disposed inside the baffle 52, a duct 51 and a baffle 52, and a short path prevention plate 54 that prevents a hot gas short path.
As the hot gas temperature rises during boiler operation, the temperature of structures such as the duct 51, the baffle 52, the heat transfer tube 53, or the short path prevention plate 54 also rises. Therefore, the thermal expansion of these structures is taken into consideration. The short path preventing plate 54 is installed so that a gap 55 is formed between the path preventing plate 54 and the inner wall of the duct 51.

However, the gap 55 between the short path prevention plate 54 and the inner wall of the duct 51 becomes a passage for hot gas, and a short path of hot gas is generated, so that the heat exchange performance cannot be maintained to the maximum. .
On the other hand, in Patent Document 1 (Japanese Patent Laid-Open No. 2004-301479), an intermediate baffle that prevents a short path of hot gas is provided between the duct and the heat transfer tube group, and the intermediate baffle joint portion is not completely fixed. An exhaust heat recovery boiler having a structure in which an intermediate baffle slides by displacement of a heat transfer tube group in the first operation is disclosed.

JP 2004-301479 A

  However, in the exhaust heat recovery boiler disclosed in Patent Document 1, the sealing property between the intermediate baffle and the duct side is not high, and a short path of hot gas passing through this portion cannot be completely prevented. In addition, the intermediate baffle is configured to slide when the pin slides through the long hole, but after the intermediate baffle slides according to the gap that becomes narrow due to thermal expansion, the temperature of the hot gas decreases and the gap widens. In this case, since the intermediate baffle cannot be moved in accordance with the gap, a gap is formed between the intermediate baffle and the duct, and the hot gas may be short-passed from there. Thus, it has not become the structure corresponding to the temperature fluctuation of a hot gas.

  Therefore, in view of the problems of the prior art, the present invention is an exhaust heat recovery boiler capable of preventing a short path of hot gas between the duct and the baffle without generating abnormal stress due to thermal expansion of the structure during boiler operation. The purpose is to provide.

  In order to solve the above-described problems, an exhaust heat recovery boiler according to the present invention includes a duct through which hot gas flows, a baffle disposed along the inner surface of the duct inside the duct, and disposed inside the baffle. A plurality of heat transfer tubes, and a short path prevention plate and a gas seal plate which are disposed in a space between the duct and the baffle and which block the hot gas which short passes through the space, The gas seal plate projects from one of the duct and the baffle to the other so that a gap is formed between the duct and the baffle. The gas seal plate has one end fixed and the other end free. And is arranged such that the gap between the fixed end and the free end is curved so as to protrude toward the downstream side in the flow direction of the hot gas so as to close the gap.

According to the present invention, during boiler operation, a structure such as a heat transfer tube, a baffle, a duct, a short path prevention plate, or a gas seal plate is thermally expanded by the hot gas, and a space between the duct inner surface and the baffle outer surface is formed. Even when the gas seal plate is changed, one end of the gas seal plate is a fixed end and the other end is a free end, so that abnormal stress is not generated in these structures, and the boiler can be operated smoothly.
In addition, the gas seal plate is curved to close the gap between the inner surface of the duct or the outer surface of the baffle and the short path prevention plate, so even if the temperature of the hot gas fluctuates, the gap between the inner surface of the duct and the outer surface of the baffle Can be closed without gaps.
Furthermore, since the gas seal plate is curved so as to protrude toward the downstream side in the hot gas flow direction, a differential pressure is applied in the direction of pressing the free end of the gas seal plate against the contact surface during boiler operation. Sealability can be improved.

  As a result, even when there is a temperature fluctuation of the hot gas during boiler operation and the gap width between the inner surface of the duct or the outer surface of the baffle and the short path prevention plate changes, the free end of the gas seal plate is caused by the restoring force of the gas seal plate. Can be always pressed against the contact surface, and it is possible to prevent a gap from being formed between the gas seal plate and the contact surface, thereby reliably preventing a short path of hot gas.

Preferably, the short path prevention plate is fixed to the baffle, and the gas seal plate has the fixed end fixed to the short path prevention plate and the free end contacting the inner surface of the duct. .
As described above, since the short path prevention plate is fixed to the baffle side, the short path prevention plate and the gas seal plate can be reliably positioned at the portion where the heat transfer tube is installed. Further, by fixing the short path prevention plate and the gas seal plate, the gas seal plate can be easily attached. Furthermore, since the free end of the gas seal plate is in contact with the inner surface of the duct, the hot gas flows between the gas seal plate and the inner surface of the duct during boiler operation, so that a gap between the gas seal plate and the inner surface of the duct is formed. It can be surely prevented from opening.

  Further, at this time, the gas seal plate is fixed to a surface on the downstream side in the hot gas flow direction of the short path prevention plate, and the short path prevention plate is curved so as to follow the gas seal plate. Preferably, this prevents the stress from concentrating on the curved portion of the gas seal plate by the edge of the end portion of the short path prevention plate, thereby preventing the gas seal plate from being damaged.

The short path prevention plate is fixed to the baffle, and the gas seal plate has the fixed end fixed to the inner surface of the duct, and the free end is the short path prevention upstream of the hot gas flow direction. It is preferably in contact with the surface of the plate.
In this manner, the short path prevention plate is fixed to the baffle side, so that the short path prevention plate can be reliably positioned at the site where the heat transfer tube is installed. Further, since the gas seal plate is fixed to the inner surface of the duct, the bonding strength of the gas seal plate can be increased, and the stress of the fixing portion of the short path prevention plate can be reduced. Furthermore, since the free end of the gas seal plate is in contact with the surface of the short path prevention plate, the hot gas flows between the gas seal plate and the duct inner surface during boiler operation, so that the gas seal plate and the duct inner surface are Can be surely prevented from opening a gap.

  Preferably, the fixed end of the gas seal plate is fixed by a plurality of fixing means, and a band plate is interposed between the fixed end and the plurality of fixing means. It is possible to prevent the gas seal plate from being broken due to dispersion.

  Furthermore, it is preferable that the strip is curved so as to follow the gas seal plate, thereby preventing stress from being concentrated on the curved portion of the gas seal plate by the edge of the strip plate, It can be prevented from being damaged.

Moreover, it is preferable to further provide a receiving plate that limits the amount of displacement of the free end of the gas seal plate.
Thus, by providing the receiving plate for limiting the amount of displacement of the free end of the gas seal plate, it is possible to prevent the free end of the gas seal plate from hanging away from the contact surface.

As described above, according to the present invention, even when the structure is thermally expanded during boiler operation and the space between the duct inner surface and the baffle outer surface changes, one end of the gas seal plate is a fixed end and the other end is Since it is a free end, abnormal stress does not occur in these structures, and the boiler can be operated smoothly.
In addition, the gas seal plate is curved to close the gap between the inner surface of the duct or the outer surface of the baffle and the short path prevention plate, so even if the temperature of the hot gas fluctuates, the gap between the inner surface of the duct and the outer surface of the baffle Can be closed without gaps.
Furthermore, since the gas seal plate is curved so as to protrude toward the downstream side in the hot gas flow direction, a differential pressure is applied in the direction of pressing the free end of the gas seal plate against the contact surface during boiler operation. Sealability can be improved.

It is a whole lineblock diagram showing an example of an exhaust heat recovery boiler concerning an embodiment of the present invention. It is the notch perspective view which expanded the heat exchanger tube part of the waste heat recovery boiler. It is a figure which shows the AA cross section of FIG. 2, and is sectional drawing which shows a short path | pass prevention means. It is sectional drawing which shows the 1st modification of FIG. It is sectional drawing which shows the 2nd modification of FIG. It is a perspective view which shows the short path | pass prevention means provided with the strip. FIGS. 7A and 6B are views showing a modification of FIG. 6, in which FIG. 6A is a cross-sectional view in which a band plate is attached to the short path prevention plate side, and FIG. It is sectional drawing which curved the short path | pass prevention board. It is a figure which shows the short path prevention means provided with the receiving plate, (A) is sectional drawing which attached the receiving plate to the duct side, (B) is sectional drawing which attached the receiving plate to the short path preventing plate side. It is sectional drawing which shows the short path | pass prevention board of the conventional waste heat recovery boiler.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  With reference to FIG.1 and FIG.2, the exhaust heat recovery boiler which concerns on embodiment of this invention is demonstrated. FIG. 1 is an overall configuration diagram showing an example of an exhaust heat recovery boiler according to an embodiment of the present invention, and FIG. 2 is an enlarged cutaway perspective view of a heat transfer tube portion of the exhaust heat recovery boiler. As an example, FIG. 1 shows a vertical exhaust heat recovery boiler that recovers heat of a hot gas (exhaust gas) of a gas turbine in a gas turbine combined cycle power plant. However, the present invention is not limited to this. Further, the exhaust heat recovery boiler may be either a vertical type in which hot gas flows in the vertical direction or a horizontal type in which hot gas flows in the horizontal direction.

An exhaust heat recovery boiler 1 according to an embodiment of the present invention includes a heat exchange section (heat transfer tube) 5 such as a economizer, an evaporator, or a superheater inside a duct 2 extending in a vertical direction. The hot gas discharged from the gas turbine or the like is introduced into the duct 2 from the duct inlet 3, sequentially passes through the plurality of heat exchanging units 5, and is recovered from the chimney 4 after being recovered.
The heat exchange part 5 has a plurality of heat transfer tubes extending in the horizontal direction so as to intersect the gas flow direction. A header 8 connecting the plurality of heat transfer tubes 5 is provided outside the duct 2 through the duct 2. Each of the headers 8 is connected to the steam drum 9 via a connecting pipe and a down pipe (not shown). In FIG. 1, the heat transfer tubes 5 are displayed in a square shape for schematic display, but this is an aggregate display of a plurality of heat transfer tubes 5, and one between the heat transfer tubes 5 and the header 8. This is also a schematic illustration of a state in which a plurality of heat transfer tubes 5 are gathered together.

The plurality of heat transfer tubes 5 are supported by a support plate 6 and disposed inside the baffle 7. The baffle 7 is fixed to the support plate 6 by welding or the like, and is disposed along the inner surface of the duct 2. The support plate 6 or the baffle 7 is suspended from the duct 2, for example, so that the plurality of heat transfer tubes 5 are arranged at predetermined positions in the duct 2.
A space 20 is formed between the inner surface of the duct 2 and the outer surface of the baffle 7. Short path prevention means 10 is installed in this space 20.
The short path prevention means 10 prevents the hot gas from short-passing the space 20 between the inner surface of the duct 2 and the outer surface of the baffle 7.

  The short path prevention means 10 includes a short path prevention plate 11 and a gas seal plate 12. The short path prevention plate 11 is disposed so as to project from one of the duct 2 and the baffle 7 toward the other so that a gap is formed between the other. The gas seal plate 12 is arranged so that one end is a fixed end and the other end is a free end, and is curved so as to be convex toward the downstream side in the gas flow direction between the fixed end and the free end to close the gap. ing.

A specific configuration of the short path preventing means 10 is shown in FIGS.
FIG. 3 is a cross-sectional view showing the AA cross section of FIG. 2 and showing the short path preventing means. The short path prevention plate 11 is disposed substantially perpendicular to the gas flow direction in the space 20 between the inner surface of the duct 2 and the outer surface of the baffle 7, and one end 11 a is fixed to the baffle 7. A gap is formed between the side end portion 11 b and the duct 2. The short path preventing plate 11 is formed of a material having rigidity such as a steel plate.

The gas seal plate 12 is a fixed end in which one end portion 12a is connected to the end portion 11b of the short path prevention plate 11, and the other end portion 12b is a free end. The end 12 a of the gas seal plate 12 is fixed to the surface on the upstream side in the gas flow direction of the short path prevention plate 11 by fixing means 13. In the drawing, a configuration in which the bolt is fixed as an example is shown, but the fixing means 13 is not limited to this.
The gas seal plate 12 is longer than the gap between the short path prevention plate 11 and the inner surface of the duct 2, and the gas flow direction is between the fixed end 12 a and the free end 12 b. It is curved so as to be convex toward the downstream side, and is arranged so as to close the gap between the short path prevention plate 11 and the inner surface of the duct 2. The gas seal plate 12 is preferably formed of a material having rigidity such as a steel plate, for example, and has a wall thickness that has a restoring force when bent.

  As described above, according to the present embodiment, the structure such as the heat transfer tube 5, the baffle 7, the duct 2, the short gas prevention plate 11, or the gas seal plate 12 is thermally expanded by the hot gas when the boiler is operated, Even when the space between the outer surface of the baffle 7 changes, the gas seal plate 12 has one end 12a as a fixed end and the other end 12b as a free end, so that abnormal stress is generated in these structures. The boiler can be operated smoothly.

In addition, since the gas seal plate 12 is curved to close the gap between the inner surface of the duct 2 and the short path prevention plate 7, there is no gap between the inner surface of the duct 2 and the outer surface of the baffle 7 regardless of the temperature fluctuation of the hot gas. It can be closed without any problems.
Further, since the gas seal plate 12 is curved so as to protrude toward the downstream side in the gas flow direction, a differential pressure is applied in the direction in which the gas seal plate 12 is pressed against the inner surface of the duct 2 during boiler operation. Can be improved.

In addition, since the short path prevention plate 11 is fixed to the baffle 7 side, the short path prevention plate 11 and the gas seal plate 12 can be reliably positioned at the portion where the heat transfer tube 5 is installed. Further, by fixing the short path prevention plate 11 and the gas seal plate 12, the gas seal plate 12 can be easily attached. Further, since the end 12b, which is the free end of the gas seal plate 12, is in contact with the inner surface of the duct 2, the hot gas flows between the gas seal plate 12 and the inner surface of the duct 2 during the boiler operation, and the gas seal It is possible to reliably prevent a gap between the plate 12 and the inner surface of the duct 2 from being opened.
The gas seal plate 12 is preferably in surface contact with the inner surface of the duct 2, thereby ensuring contact between the gas seal plate 12 and the inner surface of the duct 2 even when there are protrusions or the like on the inner surface of the duct 2. It is possible to reliably prevent a short pass of hot gas.

  Furthermore, it is preferable that the end portion 12 b which is a free end of the gas seal plate 12 is urged in a direction to close the gap between the short path prevention plate 11 and the inner surface of the duct 2 by the restoring force of the gas seal plate 12. . This can be achieved, for example, by selecting the material and thickness of the gas seal plate 12 having a restoring force such that the end 12b of the gas seal plate 12 is urged against the inner surface of the duct 2. Thus, even when the temperature of the hot gas varies during boiler operation and the gap width between the inner surface of the duct 2 and the short path prevention plate 11 changes, the gas seal plate 12 can be freely moved by the restoring force of the gas seal plate 12. The end can always be pressed against the inner surface of the duct 2, and it is possible to prevent a gap from being formed between the gas seal plate 12 and the inner surface of the duct 2, thereby reliably preventing a short path of hot gas.

FIG. 4 is a sectional view showing a first modification of the short path preventing means 10 shown in FIG.
This short path prevention means 10 has a configuration in which a gas seal plate 12 is attached to the downstream surface of the short path prevention plate 11 in the gas flow direction. As shown in FIGS. 3 and 4, the gas seal plate 12 may be attached to any surface of the short path prevention plate 11, and the attachment surface is preferably selected according to the boiler structure.

FIG. 5 is a cross-sectional view showing a second modification of the short path preventing means 10 shown in FIG.
The short path preventing means 10 includes a gas upstream surface on the free end 11b side of the short path preventing plate 11 fixed on the baffle 7 side, a gas downstream surface on the free end 12a side of the gas seal plate 12 fixed on the duct 2 side, and Are arranged so as to contact each other.
An end 12b, which is a fixed end of the gas seal plate 12, is fixed by the fixing means 13 on the upstream side in the gas flow direction from the short path prevention plate 11, and is curved so that the gas seal plate 12 is convex on the downstream side in the gas flow direction. The end portion 12a which is the free end is in contact with the end portion 11b of the short path prevention plate 11.
As described above, since the gas seal plate 12 is fixed to the inner surface of the duct 2, the bonding strength of the gas seal plate 12 can be increased, and the stress of the fixing portion of the gas seal plate 12 can be reduced.

FIG. 6 is a perspective view showing the short path preventing means 10 provided with the band plate 14.
This is a configuration in which a long strip 14 is interposed between a plurality of fixing means 13 for fixing the gas seal plate 12 and the gas seal plate 12. Thus, by providing the strip 14, it is possible to prevent the gas seal plate 12 from being damaged due to the stress due to the fixing means 13 being dispersed.
In addition, the structure which interposes the strip 14 is applicable also to the short path | pass prevention means 10 shown in either of FIG. 3 thru | or FIG.

7A and 7B are views showing a modification of FIG. 6, in which FIG. 7A is a cross-sectional view in which the strip 14 is attached to the short path prevention plate 11 side, and FIG. 7B is a cross-section in which the strip 14 is attached to the duct 2 side. FIG.
This has a configuration in which a strip 14 interposed between a plurality of fixing means 13 for fixing the gas seal plate 12 and the gas seal plate 12 is curved along the gas seal plate 12. The curvature of the band plate 14 is preferably at least larger than the curvature of the curvature of the gas seal plate 12.
Thus, by curving the strip 14 along the gas seal plate 12, stress is prevented from concentrating on the curved portion of the gas seal plate 12 due to the edge of the strip 14, and the gas seal plate 12 is damaged. Can be prevented.

FIG. 8 is a side view of the short path preventing plate 11 curved.
This is because the gas seal plate 12 is fixed to the downstream surface of the short path prevention plate 11 in the gas flow direction, and the end portion 11b of the short path prevention plate 11 is curved along the gas seal plate 12. It has become. It is preferable that the curvature of the short path prevention plate 11 is at least larger than the curvature of the curvature of the gas seal plate 12.
In this way, by curving the short path prevention plate 11 along the gas seal plate 12, it is possible to prevent stress from being concentrated on the curved portion of the gas seal plate 12 by the edge of the end portion 11b of the short path prevention plate 11. The gas seal plate 12 can be prevented from being damaged.

9A and 9B are views showing the short path preventing means 10 provided with the receiving plate 15. FIG. 9A is a sectional view in which the receiving plate 15 is attached to the duct 2 side, and FIG. It is sectional drawing attached to 11 side.
The short path prevention means 10 shown in FIG. 9A has a configuration in which a gas seal plate 12 is fixed to a short path prevention plate 11 fixed to the baffle 7. At this time, the gas seal plate 12 is provided on the inner surface of the duct 2. A receiving plate 15 is provided for limiting the amount of displacement of the end portion 12b, which is the free end of the. The receiving plate 15 has an L-shaped cross section as shown in the figure, for example, and the end 12 b of the gas seal plate 12 is accommodated in the receiving plate 15.

  The shape of the receiving plate 15 is not limited to the configuration shown in the drawing, and may be another configuration such as an annular shape into which the end 12b of the gas seal plate 12 can be inserted.

The short path preventing means 10 shown in FIG. 9B has a short path preventing plate 11 fixed to the baffle 7 and a gas seal plate 12 fixed to the duct 2, and at this time, the short path preventing plate 11. A receiving plate 15 for limiting the amount of displacement of the end 12a of the gas seal plate 12 is provided on the gas seal plate contact surface. The structure of the receiving plate 15 is the same as that shown in FIG.
Thus, by providing the receiving plate 15 that restricts the amount of displacement of the free end of the gas seal plate 12, it is possible to prevent the free end of the gas seal plate 12 from drooping away from the contact surface.

  In the above-described short path preventing means 10, the example in which the short path preventing plate 11 is provided on the baffle 7 side has been described, but the short path preventing plate 11 may be provided on the duct 2 side.

DESCRIPTION OF SYMBOLS 1 Waste heat recovery boiler 2 Duct 3 Duct inlet 4 Chimney 5 Heat transfer tube 6 Support plate 7 Baffle 8 Header 9 Steam drum 10 Short path prevention means 11 Short path prevention board 12 Gas seal board 13 Fixing means (bolt)
14 Band plate 15 Base plate 20 Space

Claims (8)

A duct through which hot gas flows;
A baffle disposed inside the duct along an inner surface of the duct;
A plurality of heat transfer tubes disposed inside the baffle;
A short path prevention plate and a gas seal plate which are arranged in a space between the duct and the baffle, and which block the hot gas which short-passes the space;
The short path prevention plate projects from one of the duct and the baffle toward the other so that a gap is formed between the other and the other.
The gas seal plate has a fixed end at one end and a free end at the other end. The gas seal plate is curved so that the gap between the fixed end and the free end protrudes downstream in the hot gas flow direction. An exhaust heat recovery boiler arranged to be closed.   The exhaust heat recovery boiler according to claim 1, wherein the free end of the gas seal plate is urged in a direction to close the gap by a restoring force of the gas seal plate. The short path prevention plate is fixed to the baffle,
3. The exhaust heat recovery boiler according to claim 1, wherein the fixed end of the gas seal plate is fixed to the short path prevention plate, and the free end is in contact with an inner surface of the duct.   The gas seal plate is fixed to the downstream surface of the short path prevention plate in the hot gas flow direction, and the short path prevention plate is curved along the gas seal plate. The exhaust heat recovery boiler according to claim 3. The short path prevention plate is fixed to the baffle,
The gas seal plate is characterized in that the fixed end is fixed to the inner surface of the duct, and the free end is in contact with the surface of the short path prevention plate on the upstream side in the flow direction of the hot gas. The exhaust heat recovery boiler according to 1 or 2.   6. The gas seal plate according to claim 1, wherein the fixed end of the gas seal plate is fixed by a plurality of fixing means, and a band plate is interposed between the fixed end and the plurality of fixing means. An exhaust heat recovery boiler according to claim 1.   The exhaust heat recovery boiler according to claim 6, wherein the band plate is curved so as to follow the gas seal plate.   The exhaust heat recovery boiler according to any one of claims 1 to 7, further comprising a receiving plate that limits a displacement amount of the free end of the gas seal plate.

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