JP2018162959A - Exhaust heat recovery boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resume function of a seal plate after recovery from thermal warpage of the inner structure by which the seal plate formed of an elastic material to block short pass between a casing inner wall and the inner structure loses its function.SOLUTION: There is provided a seal mechanism 30 making a seal plate 32 formed of an elastic material cantilevered by a baffle member 31 in substantially parallel with the inner wall surface of a casing 3 come into contact with a seal surface 33 on which a free end of the convex side is formed on a peripheral edge part of the inner structure being curved in a direction to be separated from the corresponding inner wall surface, in which the seal mechanism arranged on a predetermined peripheral edge part of the inner structure includes a curvature maintaining member 34 for holding the seal plate at or above a predetermined curvature.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an exhaust heat recovery boiler that recovers heat of exhaust gas such as a gas turbine to generate steam.

  A casing constituting the flue of the exhaust heat recovery boiler accommodates a heat transfer tube structure that constitutes a heat exchanger such as a superheater, a reheater, an evaporator, and a economizer that recovers exhaust heat. Further, a structure in which a denitration catalyst for removing harmful substances such as nitrogen oxides in exhaust gas is assembled is accommodated. These heat transfer tube structures and denitration catalyst structures are collectively referred to as internal structures in this specification.

  These internal structures are installed in a casing to circulate exhaust gas. Further, in consideration of the difference in thermal expansion between the casing and the internal structure, a gap is formed between the outer peripheral wall of the internal structure and the casing inner wall. However, if there is a short path through which the exhaust gas does not circulate through the internal structure, there is a disadvantage that the heat recovery rate is reduced or the harmful substance removal rate is reduced. Therefore, a seal mechanism (seal system) that blocks the gap is provided (for example, Patent Documents 1 and 2).

  The heat recovery boiler of Patent Document 1 sequentially arranges heat transfer tube groups that are a plurality of internal structures along a flow of exhaust gas in a so-called vertical duct (flue) in which exhaust gas is circulated from the lower part to the upper part. It is arranged and configured. Each internal structure has a flat baffle on both sides facing the inner wall surface of the duct, and a sealing mechanism is provided to block the short path of the upward flow of exhaust gas that passes through the gap between the inner wall surface of the duct and the baffle. . In particular, the seal mechanism is supported by a baffle and extends substantially horizontally toward the inner wall surface of the duct and extends in a direction perpendicular to the exhaust gas flow, and a tip of the short path prevention plate. And a sealing plate made of an elastic material supported in a cantilever manner. The seal plate is provided in such a manner that the seal plate is curved in an arc shape with respect to the fixed end, the free end side extends toward the inner wall surface of the duct, and is brought into sliding contact with the inner wall surface of the duct. Thereby, the short path | pass of the waste gas between a duct and a baffle can be prevented, without generating the abnormal stress by the thermal expansion of the structure of a waste heat recovery boiler. A similar sealing mechanism can be provided even when the direction of the exhaust gas flow in the vertical duct is downward.

  On the other hand, Patent Document 2 discloses a heat recovery boiler for a horizontal duct (flue) through which exhaust gas is circulated in the lateral direction. In the case of a horizontal heat recovery boiler, as specifically described in Patent Document 3, a plurality of heat transfer tube structures are sequentially arranged along the exhaust gas flow. In Patent Documents 2 and 3, a denitration catalyst structure is housed as an internal structure in addition to the heat transfer tube structure. Also in this case, a gap is formed between the inner wall of the horizontal casing that forms the flue and the outer peripheral wall of the internal structure. Therefore, Patent Document 2 is provided with a seal mechanism for blocking a short path of the exhaust gas passing through the gap between the inner wall surface of the casing and the outer periphery of the internal structure at the peripheral edge of the internal structure upstream of the exhaust gas.

  In the sealing mechanism of Patent Document 2, a baffle member that blocks a short path is provided on the inner wall of the casing, the seal plate made of an elastic material is cantilevered on the baffle member, the seal plate is curved in an arc shape, and the curved convex surface is formed. The plate surface on the free end side is configured to contact the seal surface formed on the peripheral edge of the internal structure upstream of the exhaust gas toward the downstream side of the exhaust gas. According to such a sealing mechanism, similarly to Patent Document 1, even if a difference in thermal expansion between the casing and the internal structure occurs, the seal plate made of an elastic material absorbs the difference in thermal expansion, and the free end of the seal plate Since the contact position with the seal surface slides, the short path of exhaust gas can be blocked.

Japanese Patent No. 5374349 Japanese Patent No. 5581494 JP2008-082626

  However, with the technological development, the temperature of the exhaust gas from the gas turbine in the combined cycle tends to increase. Further, the exhaust gas flow rate in the exhaust heat recovery boiler also tends to be increased (dynamic pressure increase). When the exhaust gas temperature becomes high, for example, the temperature difference between the upstream side and the downstream side of the exhaust gas of the internal structure may temporarily increase due to a temperature change at startup or a load change. Thereby, when a temporary thermal expansion difference due to the temperature difference between the upstream side and the downstream side of the internal structure occurs, the internal structure may be warped as a whole due to this thermal expansion difference, which may cause a thermal warp. The conventional seal mechanism may not be able to cope with the thermal warp of the internal structure.

  For example, in the case of a horizontal heat recovery boiler, a denitration catalyst structure that is an internal structure is generally assembled in a rectangular parallelepiped shape by arranging a plurality of catalyst layers on a frame member in a three-dimensional manner. Such a denitration catalyst structure may employ a self-supporting support structure that is supported by a base member provided on the bottom side of a horizontal casing. Since the upper end of the self-supporting denitration catalyst structure is a free end, if the temperature difference between the upstream frame member and the downstream frame member is large, the upper side away from the lower support point will greatly warp downstream. Become. In particular, when the temperature difference between the upstream side and the downstream side of the denitration catalyst structure becomes large, the warp of the exhaust gas becomes extremely large. Moreover, there is a risk of increasing the dynamic pressure acting on the denitration catalyst structure due to the increase in the speed of the exhaust gas flow and promoting warpage.

  Thus, when the thermal warpage of the self-supporting denitration catalyst structure becomes extremely large, the distance between the baffle member supported on the casing side and the seal surface formed at the upper peripheral edge of the denitration catalyst structure is increased. The arcuate curve of the sealing plate having elasticity may be extended far away. When the free end of the seal plate is separated from the seal surface, the function of blocking the exhaust gas short path is lost. Even if the seal plate does not fully extend, it is conceivable that the elastic force of the seal plate will cause it to jump from the seal surface and leave the seal surface. When the seal plate is in such a state, even if the temperature change of the exhaust gas is settled and the thermal warping of the denitration catalyst structure is reduced, the once extended seal plate does not return to the initial state (curved). Therefore, since the function of the seal mechanism is not restored, it is necessary to stop and repair the plant.

  The above-described problem is not limited to a self-supporting internal structure, but can also occur in the case of a denitration catalyst structure suspended from an upper structural member of a horizontal casing. That is, in the case of a suspended internal structure, the temperature difference between the upstream side and the downstream side of the frame member becomes large, and the free end on the lower end side of the rectangular parallelepiped frame member warps downstream. This amount of warpage is smaller than the self-supporting type because of its own weight, but the same problem can occur.

  The problem to be solved by the present invention is that even when the sealing plate made of an elastic material that blocks a short path between the casing inner wall and the internal structure loses its function due to the thermal warp of the internal structure, the thermal warpage is recovered. It is to provide an exhaust heat recovery boiler that can sometimes recover its function.

  In order to solve the above problems, an exhaust heat recovery boiler according to the present invention includes a casing that forms a horizontal flue, an internal structure that is accommodated in the casing and through which exhaust gas flows, an inner wall of the casing, and the A seal mechanism that blocks a short path of the exhaust gas flowing through a gap formed between the internal structure and the seal mechanism, corresponding to a peripheral edge of the internal structure on the upstream side of the exhaust gas, A baffle member supported by the inner wall of the casing along the extending direction of the peripheral edge, and a seal plate made of an elastic material cantilevered by the baffle member substantially parallel to the inner wall surface of the casing. The seal plate is bent in a direction away from the corresponding inner wall surface, and the free end on the convex surface side is brought into contact with the seal surface formed on the peripheral edge portion, and the periphery of the set position of the internal structure is formed. The said sealing mechanism provided in parts, and characterized in that it comprises a curvature holding member for holding the sealing plate to the curvature of the above set curvature.

  According to the sealing mechanism (short path prevention mechanism) of the present invention, the problem can be solved by the following action. As described above, conventionally, when the temperature difference between the upstream side and the downstream side of the internal structure becomes large, the sealing mechanism may not be restored due to the thermal warping of the internal structure. However, according to the present invention, even if the sealing surface is greatly separated from the baffle member due to the thermal warping of the internal structure, the arc-shaped curve of the seal plate is held above the set curvature by the curvature holding member supported by the baffle member. Is done. As a result, in the process where the temperature change of the exhaust gas flowing through the exhaust heat recovery boiler is settled and the thermal warpage of the internal structure is reduced, the plate surface at the free end of the seal plate contacts the seal surface, and the warpage of the internal structure The seal plate is again bent into an arc shape by the restoring force. Thereby, when the warping of the internal structure is restored, the seal mechanism is restored, and the function of the seal mechanism is restored.

  In other words, according to the present invention, in the exhaust heat recovery boiler during operation, it is generated between the upstream side and the downstream side of the internal structure following the thermal expansion of the internal structure without generating excessive stress. Even if the internal structure warps downstream due to the difference in gas temperature, the function of the sealing mechanism can be recovered if the exhaust gas temperature of the exhaust heat recovery boiler reaches a steady state.

  In this case, the peripheral edge of the preset position is the thermal distortion of the internal structure due to the difference in thermal expansion between the upstream side and the downstream side of the exhaust gas of the internal structure, and the baffle member and the sealing surface of the internal structure What is necessary is just the peripheral part of an internal structure that distance reaches more than a setting value.

  Therefore, in the case of a self-supporting internal structure that is supported by the bottom structure of the casing and is self-supported, the peripheral edge of the preset position is at least of the internal structure facing the ceiling wall of the casing. Upper peripheral edge. Moreover, although the peripheral part of the side part connected to an upper peripheral part may be included, the peripheral part of a side part may be a conventional seal mechanism. On the other hand, in the case of a suspended internal structure, it is at least the lower peripheral edge of the internal structure facing the bottom wall of the casing. Moreover, although the peripheral part of the side part of the internal structure connected to a lower peripheral part may be included, the peripheral part of a side part may be a conventional seal mechanism.

  Moreover, you may provide a curvature holding member continuously or at intervals along the peripheral part of an internal structure. Further, the curvature holding member may have a curved portion in contact with the convex surface of the seal plate, and the curved portion may be formed on a curved surface having a set curvature or more.

  The seal plate may be formed by laminating a plurality of plates having different lengths from the fixed end to the free end.

  The fixed end of the seal plate is preferably fixed to the baffle member parallel to the inner wall of the casing. In this case, a surface parallel to the inner wall of the casing for fixing the seal plate may be formed on the baffle member, or a member having a surface parallel to the inner wall of the casing for fixing the seal plate may be fixed to the baffle member. Good.

  The curvature holding member may be formed integrally with the baffle member, or may be formed by a separate member and fixed to the baffle member. The baffle member has an L-shaped cross section, and is provided with one end of the L shape supported on the inner wall of the casing and the other end substantially parallel to the inner surface toward the periphery of the internal structure, and a curvature holding member. May be a curvature holding portion that is integrally formed by bending the tip of the other end facing substantially parallel to the inner surface of the baffle member in a direction away from the inner surface according to the set curvature.

  The seal plate may be fixed to the baffle member via the first flat plate member, and the seal surface may be formed on the surface of the second flat plate member fixed to the peripheral edge portion of the internal structure. In this case, the first flat plate member and the second flat plate member are formed by being divided into a plurality along the extending direction of the peripheral portion of the internal structure, and the seal plate is formed by the first flat plate member and the second flat plate member. It is divided into a plurality of parts in accordance with the division of the flat plate member.

  According to the present invention, even when the sealing plate made of an elastic material that blocks a short path between the casing inner wall and the internal structure loses its function due to the thermal warp of the internal structure, the function is achieved when the thermal warpage is recovered. A recoverable exhaust heat recovery boiler can be provided.

1 is an external perspective view showing a part of an embodiment of a horizontal exhaust heat recovery boiler according to the present invention in a broken state. It is a schematic diagram which shows the principal part cross section of one Embodiment of the waste heat recovery boiler of this invention. It is sectional drawing which shows the sealing mechanism of one Embodiment of the waste heat recovery boiler of this invention. It is sectional drawing of the conventional sealing mechanism explaining the effect of the sealing mechanism of this invention. It is a perspective view which shows the sealing mechanism of other embodiment of the waste heat recovery boiler of this invention.

  As shown in FIG. 1, a horizontal exhaust heat recovery boiler 1 according to an embodiment to which the present invention is applied includes a plurality of heat transfer tube structures 5 including a heat transfer tube group in a casing 3 that forms a horizontal flue. Is accommodated along the flow direction of the exhaust gas 2. In these heat transfer tube structures 5, the exhaust gas 2 after working in the gas turbine is circulated, and the energy of the exhaust gas is recovered to generate steam. The generated steam is used in a combined cycle power plant that supplies power to an external steam turbine via the brackish water separation drum 6 to generate electric power. Further, the denitration catalyst structure 20 is accommodated in an appropriate exhaust gas temperature region between the plurality of heat transfer tube structures 5. The casing 3 includes left and right side wall surfaces and upper and lower wall surfaces made of steel plates, a reinforcing member 10 that reinforces these, and the like. In addition, although the heat transfer tube structure 5 of this embodiment is a suspended internal structure, it may be a self-supporting heat transfer tube structure and may be a target to which the present invention is applied.

  In the denitration catalyst structure 20 of the present embodiment, as shown in the cross-sectional view of FIG. 2, the high-temperature exhaust gas 2 discharged from the gas turbine is configured by the casing 3 of the exhaust heat recovery boiler 1 as indicated by an arrow. Circulated from upstream to downstream through the flue. A denitration catalyst structure 20 that removes harmful substances such as nitrogen oxides is housed in the flue. A heat insulating material 3b is provided on the inner surface of the ceiling wall 3a of the casing 3, and a heat insulating material 3d is provided on the bottom wall 3c. Although not shown in the figure, the left and right side walls of the casing 3 are similarly formed. Although not shown, the denitration catalyst structure 20 is formed in a rectangular parallelepiped shape by assembling a plurality of catalyst layers on a frame member in a three-dimensional manner. The rectangular parallelepiped denitration catalyst structure 20 is supported by a base member 21 having a lower portion provided on the bottom side of the horizontal casing 3, and the upper portion is separated from the ceiling wall 3 a of the casing 3 by a gap 4 and is not supported. It has become. The sealing mechanism according to the denitration catalyst structure 20 of the present embodiment significantly corresponds to the problem of the present invention.

  Next, the details of the sealing mechanism which is a feature of the present invention will be described. As shown in FIG. 2, the seal mechanism 30 of the present embodiment is arranged so that the ceiling wall 3 a of the casing 3 and the denitration catalyst structure 20 are opposed to the upper peripheral portion on the upstream side of the exhaust gas of the denitration catalyst structure 20. It is provided so as to block the short path of the exhaust gas flowing through the gap 4 formed therebetween. Although not shown, a seal mechanism is also provided opposite to the peripheral portion other than the upper portion on the upstream side of the denitration catalyst structure 20. However, in the present embodiment, it is assumed that those sealing mechanisms can basically be handled by a conventional sealing mechanism. That is, the sealing mechanism 30 of the present invention may be provided at the peripheral edge of a preset position of the denitration catalyst structure 20 that is an internal structure.

  FIG. 3 shows a partial cross-sectional view of the seal mechanism 30 as viewed from a direction orthogonal to the flow of the exhaust gas 2. As shown in FIG. 2A, the seal mechanism 30 is provided at a predetermined distance from the upper peripheral edge of the denitration catalyst structure 20 and is supported by the ceiling wall 3 a of the casing 3. 31, a seal plate 32 made of an elastic material cantilevered by the baffle member 31, and a seal surface 33 formed on the peripheral edge of the upper end of the denitration catalyst structure 20. The seal plate 32 is formed using a highly elastic material, and is formed using, for example, a leaf spring structure in which thin plates such as stainless steel are stacked. However, it is not limited to this.

  The seal plate 32 has a fixed end that is cantilevered by the baffle member 31 and a free end that is not fixed. The seal plate 32 is supported by the baffle member 31 substantially parallel to the ceiling wall 3a, and is provided to extend in a direction away from the ceiling wall 3a. In particular, it is formed by bending between the fixed end and the free end, with its convex surface facing the downstream side of the exhaust gas, and the plate surface on the free end side in contact with the seal surface 33. Further, the seal plate 32 of the present embodiment is provided with a curvature holding member 34 that is supported by the baffle member 31 and holds the curvature at or above the set curvature.

  The fixed end of the seal plate 32 is fixed to a surface parallel to the inner surface of the ceiling wall 3a of the baffle member 31 made of L-shaped steel material, for example, with bolts and nuts 35. However, the baffle member 31 is not limited to the L-shaped steel material, and may have a shape having a surface parallel to the inner surface of the ceiling wall 3a. In short, the seal plate 32 is fixed in parallel to the inner surface of the ceiling wall 3a. I can do it. That is, the seal plate 32 is preferably cantilevered by being fixed to the baffle member 31 in parallel with the inner wall of the casing 3. In this case, a surface parallel to the inner wall of the casing 3 for fixing the seal plate 32 may be formed on the baffle member 31, and a member having a surface parallel to the inner wall of the casing 3 for fixing the seal plate 32 is formed on the baffle member 31. It may be fixed.

  The curvature holding member 34 of the present embodiment includes a base portion 34 a that is fixed to the baffle member 31 and extends toward the seal surface 33, and a holding portion 34 b that is suspended from the tip of the base portion 34 a toward the curved portion of the seal plate 32. It is formed. The tip position of the restraining portion 34b is set so as to keep the curvature of the seal plate 32 at or above the set curvature. That is, as shown in FIG. 2B, even if the warp occurs due to the difference in thermal expansion between the upstream side and the downstream side of the denitration catalyst structure 20, and the free end of the seal plate 32 is separated from the seal surface 33, the set curvature is obtained. The tip of the restraining portion 34b is provided at the position to be held as described above.

  With this configuration, according to the sealing mechanism 30 that is the short path prevention mechanism of the present embodiment, even if the sealing surface 33 is largely separated from the baffle member 31 due to thermal warping of the denitration catalyst structure 20, the sealing plate Since the elastic force of the sealing plate 32 is suppressed by the distal end of the suppressing portion 34b of the curvature holding member 34, the curvature of 32 is maintained at a set curvature or more. As a result, in the process in which the temperature change of the exhaust gas flowing through the exhaust heat recovery boiler is settled and the thermal warping of the denitration catalyst structure 20 is reduced, the plate surface at the free end of the seal plate 32 comes into contact with the seal surface 33, The seal plate 32 is bent again by the return force of the warp of the catalyst structure 20. As a result, as shown in FIG. 3C, when the warpage of the denitration catalyst structure 20 is restored, the seal mechanism is restored, and the function of the seal mechanism is restored.

  Here, a conventional sealing mechanism in which the curvature holding member 34 is not provided is shown in FIG. 4, and the effect of this embodiment will be described. FIG. 4 is different from FIG. 3 only in that the curvature holding member 34 is not provided. Therefore, the same parts as those in FIG. When the thermal warping of the denitration catalyst structure 20 becomes extremely large from the steady state of FIG. 4A as shown in FIG. 4B, the baffle member 31 is moved to the peripheral portion at the top of the denitration catalyst structure 20. The distance from the formed sealing surface 33 is greatly separated. As a result, as shown in FIG. 4C, the free end of the elastic seal plate 32 is separated from the seal surface 33 and the curve is extended, so that the function of blocking the exhaust gas short path is lost. It is also conceivable that the free end jumps up from the seal surface 33 due to the elastic force of the seal plate 32 and is separated from the seal surface. Once in this state, even if the temperature change of the exhaust gas is settled and the warp of the denitration catalyst structure 20 is reduced, the extended seal plate 32 does not return to the initial state (curved). Therefore, since the function of the conventional seal mechanism is not restored, the plant must be stopped and repaired.

  As described above, according to the present embodiment, in the exhaust heat recovery boiler during operation, the internal structure follows the thermal expansion of the denitration catalyst structure 20 that is the internal structure without generating excessive stress. If the exhaust gas temperature of the exhaust heat recovery boiler reaches a steady state even if the internal structure is warped downstream due to the gas temperature difference generated between the upstream side and the downstream side of the product, the function of the sealing mechanism can be restored. Can do.

  Here, in the above-mentioned embodiment, the denitration catalyst structure 20 is thermally warped due to the difference in thermal expansion between the upstream side and the downstream side of the exhaust gas of the denitration catalyst structure 20 from the peripheral portion of the preset position, and the baffle member 31. This is a peripheral portion where the distance between the seal surface 33 and the seal surface 33 may reach a set value or more. Therefore, the peripheral edge set in the case of a self-supporting internal structure is at least the upper peripheral edge of the internal structure facing the ceiling wall of the casing. On the other hand, in the case of a suspended internal structure, at least the lower peripheral edge of the internal structure facing the bottom wall of the casing is considered.

  The curvature holding member 34 is not limited to the above embodiment, and may be provided continuously or at intervals along the peripheral edge of the denitration catalyst structure 20 that is an internal structure. Furthermore, the curvature holding member 34 may have a curved portion in contact with the convex surface of the seal plate 32, and the curved portion may be formed on a curved surface having a set curvature or more. The seal plate 32 may be formed by stacking a plurality of thin elastic plates having different lengths from the fixed end to the free end.

  Further, the seal plate may be fixed to the baffle member via the first flat plate member, and the seal surface may be formed on the surface of the second flat plate member fixed to the peripheral edge portion of the internal structure. In this case, the first flat plate member and the second flat plate member are formed by being divided into a plurality along the extending direction of the peripheral portion of the internal structure, and the seal plate is formed by the first flat plate member and the second flat plate member. It is divided into a plurality of parts in accordance with the division of the flat plate member.

  FIG. 5 is a perspective view showing a configuration of a seal mechanism 40 according to another embodiment of the present invention. The present embodiment is an example in which the curvature holding portion 44 is formed integrally with the baffle member 31. As shown in the figure, the seal mechanism 40 is provided at a predetermined distance from the upper peripheral edge of the denitration catalyst structure 20. The baffle member 41 is formed of a steel material having an L-shaped cross section, and is provided with one end of the L shape supported on a ceiling wall of a casing (not shown) and the other end directed toward the denitration catalyst structure 20 side. The seal plate 42 made of an elastic material is sandwiched by a support portion 41 a parallel to the ceiling wall of the casing of the baffle member 41 and a press plate 46 and is cantilevered. Further, the seal plate 42 is provided in such a manner that the free end on the convex side is curved in a direction away from the ceiling wall and is in contact with the seal surface 43 formed on the peripheral edge of the upper portion of the denitration catalyst structure 20. The seal plate 42 is formed using a highly elastic material.

  The curvature holding portion 44 of the present embodiment is formed integrally with the baffle member 41 by bending the tip portion of the support portion 41a of the baffle member 41 in a direction away from the ceiling wall 3a. The bending angle of the curvature holding unit 44 is an angle that holds a predetermined curvature of the seal plate 42 at or above the set curvature. The curvature holding portion 44 is reinforced by ribs 45 fixed to the baffle member 41 so as to hold the bending angle. The curvature holding portion 44 is formed to bend the seal plate 42 at a portion closer to the fixed end than to the free end.

  As a result, the thermal warping of the denitration catalyst structure 20 increases, and even after the free end side of the seal plate 42 is separated from the seal surface 43, the curved shape of the seal plate 42 is separated by the curvature holding portion 44. Maintained. Thereby, when the thermal warpage of the denitration catalyst structure 20 is eliminated and the denitration catalyst structure 20 returns to the original position, the free end side of the seal plate 42 comes into contact with the seal surface of the denitration catalyst structure 20 again. Then, it is restored to the original curved state by the restoring force of the denitration catalyst structure 20. Thereby, the function of the seal mechanism 40 can be recovered.

  As described above, the present invention is a state when the curved shape of the seal plate is separated by the curvature holding member even after the thermal warpage of the internal structure is increased and the free end side of the seal plate is separated from the seal surface. Therefore, when the internal structure returns to the original position, the seal plate recovers to the original curved state by the return force of the internal structure, and the function of the seal mechanism can be recovered.

  As described above, according to the present invention, the curved shape of the seal plate is separated by the curvature holding member even after the thermal warpage of the internal structure is increased and the free end side of the seal plate constituting the seal mechanism is separated from the seal surface. The main purpose was to maintain the condition at the time. Instead of this, if the length of the seal plate is made sufficiently long so that the free end side of the seal plate is not separated from the seal surface even if the thermal warpage of the internal structure increases, the problem of the present invention Does not occur.

  However, lengthening the sealing plate made of an elastic material is problematic in terms of economy because the elastic material is expensive. Further, when the seal plate is lengthened, the length of the seal surface is lengthened accordingly, and it is not preferable to form the seal surface by eroding the region of the internal structure through which the exhaust gas flows.

  As mentioned above, although this invention was demonstrated based on one Embodiment, this invention is not limited to these, It is possible to implement in the form deform | transformed or changed in the range of the main point of this invention. It will be obvious to those skilled in the art, and such variations or modifications are within the scope of the claims of the present application.

DESCRIPTION OF SYMBOLS 1 Waste heat recovery boiler 2 Exhaust gas 3 Casing 3a Ceiling wall 3b Heat insulating material 5 Heat-transfer tube structure 20 Denitration catalyst structure 30 Seal mechanism 31 Baffle member 32 Seal plate 33 Seal surface 34 Curvature holding member

Claims (10)

A casing that forms a horizontal flue, an internal structure that is accommodated in the casing and through which exhaust gas flows, and a short circuit of the exhaust gas that flows through a gap formed between the inner wall of the casing and the internal structure A seal mechanism for blocking the path,
The seal mechanism includes a baffle member supported on an inner wall of the casing along an extending direction of the peripheral portion, corresponding to a peripheral portion of the internal structure upstream of the exhaust gas, and an inner wall surface of the casing A seal plate made of an elastic material that is cantilevered by the baffle member, and curved in a direction away from the corresponding inner wall surface with the free end on the convex surface side at the peripheral portion. In contact with the formed sealing surface,
The exhaust heat recovery boiler according to claim 1, wherein the seal mechanism provided at a peripheral portion at a set position of the internal structure includes a curvature holding member that holds the seal plate in a curvature that is equal to or greater than a set curvature.   The peripheral portion of the set position of the internal structure is warped by the difference in thermal expansion between the upstream side and the downstream side of the exhaust gas of the internal structure, and the baffle member and the sealing surface of the internal structure The exhaust heat recovery boiler according to claim 1, wherein the exhaust heat recovery boiler is a peripheral portion that reaches a set value or more. The internal structure is supported by the bottom structure of the casing and is self-supported and accommodated in the casing;
3. The exhaust heat recovery boiler according to claim 1, wherein a peripheral portion of the set position of the internal structure is at least an upper peripheral portion of the internal structure facing the ceiling wall of the casing. .   2. The exhaust heat recovery boiler according to claim 1, wherein the curvature holding member is provided continuously or at an interval along a peripheral edge of the internal structure.   2. The exhaust heat recovery boiler according to claim 1, wherein the curvature holding member has a curved portion in contact with the convex surface of the seal plate, and the curved portion is formed in a curved surface that is equal to or greater than the set curvature. .   The exhaust heat recovery boiler according to claim 1, wherein the seal plate is formed by stacking a plurality of plates having different lengths from the fixed end to the free end.   The exhaust heat recovery boiler according to claim 1, wherein the curvature holding member is formed integrally with the baffle member. The baffle member has an L-shaped cross-section, one end of the L-shape is supported by the inner wall of the casing, and the other end is provided substantially parallel to the inner surface toward the periphery of the internal structure.
The curvature holding member is a curvature holding portion that is integrally formed by bending a distal end portion of the other end of the baffle member that is substantially parallel to the inner surface in a direction away from the inner surface according to the set curvature. The exhaust heat recovery boiler according to claim 1. The seal plate is fixed to the baffle member via a first flat plate member,
The exhaust heat recovery boiler according to claim 1, wherein the seal surface is formed on a surface of a second flat plate member fixed to a peripheral edge portion of the internal structure. The first flat plate member and the second flat plate member are formed by being divided into a plurality along the extending direction of the peripheral edge of the internal structure,
The exhaust heat recovery boiler according to claim 9, wherein the seal plate is divided into a plurality according to the division of the first flat plate member and the second flat plate member.

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