JP2653570B2 - Exhaust heat recovery boiler header support device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

 [Object of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery boiler,
More particularly, the present invention relates to a support device for horizontal force of a header used in a large-sized waste heat recovery boiler.

[0002]

2. Description of the Related Art In general, in a combined cycle power plant, an exhaust heat recovery boiler for generating steam for driving a steam turbine or hot water for a process using exhaust gas from a gas turbine or the like as a heat source is used.

FIG. 8 shows an example of a conventional heat recovery steam generator. The exhaust heat recovery boiler shown in this figure is a so-called natural circulation type boiler in which a steam drum is arranged at the top of equipment and heat transfer tubes are installed in a vertical direction. Inflow, first superheater 4
2. The high-pressure evaporator 43 passes through a denitration device 44, where the nitrogen oxides contained therein are removed. The exhaust gas that has passed through the denitration device 44 sequentially passes through the high-pressure economizer 45, the low-pressure evaporator 46, and the low-pressure economizer 47, and exchanges heat with the internal fluid in each heat transfer tube.

[0004] Compared with a forced circulation type exhaust heat recovery boiler, a natural circulation type exhaust heat recovery boiler as shown in the figure does not require a circulation pump and has the advantage of reducing power in the plant. Since the height to the top can be kept low, the boiler duct can have a self-standing structure, and there are advantages such as the need for supporting steel frames, so that many new combined cycle power plants are installed. It is believed that this scheme is employed.

FIG. 9 is a sectional view taken along the line CC of FIG. In the figure, reference numeral 55 denotes a heat transfer tube which is arranged vertically and connected to upper and lower headers to form a panel. The casing 51 of the boiler duct is lined with a heat insulating material 52 to keep the temperature of the casing 51 close to the atmospheric temperature. The loads on the heat transfer tube 55 and the panels such as the upper and lower headers 54 and 56 are supported by a lower support member 57 installed below the lower header 56. Therefore, during operation of the exhaust heat recovery boiler, the heat transfer tube 55 and the upper header 54 are displaced vertically upward starting from the support point of the lower header 56.

As the heat transfer tube 55 of such an exhaust heat recovery boiler, a finned heat transfer tube is often used in order to efficiently recover heat from relatively low temperature gas such as gas turbine exhaust gas. In the finned heat transfer tube, the fin acts as a load mass, but does not increase the rigidity of the tube. In order to prevent the heat transfer tube 55 from buckling and to become independent, the displacement of the upper header 54 must be restrained. . For this reason, a support device for restraining the horizontal displacement of the upper header 54 is provided. The support device further has a function of supporting the load of a panel such as the heat transfer tube 55 which is the heaviest object and transmitting the load to the casing 51 even when horizontal force such as seismic force acts on the exhaust heat recovery boiler. ing. The members constituting the support device are designed to be able to resist the horizontal force during the earthquake in terms of strength.

FIGS. 10 and 11 show an example of a horizontal force transmission support structure of an upper header 54 of a conventional heat recovery steam generator.
In the example of FIG. 10, the upper header 54 is provided with a lug 62 projecting at the center of the upper header 54 to apply a horizontal force acting in a direction perpendicular to the gas flow, and the lug 62 is provided on the upper part of the casing 51.
To hold in the horizontal direction . FIG. 11
In this example, the horizontal force in the gas flow direction is supported by sandwiching a projecting member 65 provided at the end of the upper header 54 by a supporting member 66 attached to the inner surface of the casing (see FIG.
No. 61-141503).

[0008]

In recent years, combined cycle power plants have tended to increase in size due to the increase in the capacity of gas turbines. As a result, a larger exhaust heat recovery boiler has been planned. It has become to. At present, gas passage height and width exceed 10m,
Some heat recovery steam generators have a total length of more than 30 m.

In such a large-sized waste heat recovery boiler, the width of the gas passage is long, so that it is not possible to form a single header in the width direction, and a plurality of headers are divided in the width direction of the gas passage. There is a need to. In addition, it is necessary to access the upper header at the time of inspection and repair.In addition, to repair leaked pipes, lift the pipe bundle, move it, and secure the space. Sufficient space is required between 54 and the casing 51 for installing the crane rail and the lifting trolley.

In the support structure of the upper header 54 as shown in FIG. 10, the lug 62 attached to the upper header 54 or the bracket 61 on the casing 51 side needs to be long and large. However, when a horizontal force acts on the upper header 54, the former has a longer moment arm, so that excessive bending stress is generated at the root of the lug 62, that is, a welded portion with the upper header 54 which is a pressure-resistant portion. ,
There is a concern that serious problems such as welding cracks may occur. Also in the latter case, the bending stress must be shared by the bracket 61, and there is a disadvantage that the members become excessively large. When the upper header 54 is divided into a plurality of pieces in the width direction, as shown in FIG.
It is practically impossible to support the end from the casing 51 side.

Further, in the exhaust heat recovery boiler as shown in FIG. 9, since the heat insulating material 52 is adhered to the inner surface of the casing 51, a large temperature difference occurs between the temperature of the casing 51 and the temperature of the internal gas. When connecting the structural member inside 51 to the casing 51, a method of absorbing a thermal expansion difference between members due to the temperature difference becomes a problem.

It is an object of the present invention to provide a header support device capable of effectively supporting the front-rear and left-right forces acting on the upper header and capable of minimizing the thermal stress generated in the support member. With the goal. [Configuration of the Invention]

[0013]

According to the present invention, a panel is formed by connecting heat transfer tubes between vertically arranged headers, and the panel is arranged in a flow area of exhaust gas. In the header support device of the exhaust heat recovery boiler, two horizontal members arranged vertically, a vertical member extended to both horizontal members, and an oblique member extending to both horizontal members outside the vertical member are combined. Top header horizontal
Forming a truss that holds the truss in one direction, fixing one point of the truss to the ceiling plate via a fixing member, and slidably providing the other point on the ceiling plate via a sliding member along the gas flow direction. It is a feature. In addition, a pipe member is used as a horizontal member at the upper part of the truss, and the horizontal member penetrates through an annular member provided on the ceiling plate. It is characterized in that the lower horizontal member constituting the lower portion of the two trusses is connected so as to surround the periphery of the protrusion of the upper header. Further, the fixing point where the fixing member of the truss is located is set to coincide with the fixing point of the heat transfer tube panel or provided as close as possible, and the displacement direction of the truss during operation is matched with the displacement direction of the heat transfer tube panel. It is characterized by.

[0014]

According to the present invention constructed as described above, the truss for supporting the upper header is slidably supported in the gas flow direction, and the members constituting the truss are freely thermally expanded. The generation of thermal stress in the inside is suppressed.

Further, provided the truss second surface, in case of supporting the the upper header and connected to each other, and at the same time slidably supported in the gas flow direction, the truss plane freely rotating in the axial gas flow direction Therefore, even if the connecting hardware of the two trusses is thermally expanded, no out-of-plane bending deformation occurs on the truss surface, and no bending moment is transmitted to the support portion and is not transmitted to the casing.

Further, since the fixing point of the supporting device is made to coincide with the fixing point of the heat transfer tube group or a position as close as possible is selected, the difference in displacement due to the thermal expansion between the two can be minimized, and the thermal stress due to the constraint of the displacement can be minimized. Is suppressed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

1 to 3, an upper header 1 is arranged in a direction perpendicular to the gas flow, and a plurality of heat transfer tubes 2 are connected to form a panel. In this embodiment, three rows of heat transfer tubes 2 are connected to one panel, and the group of heat transfer tubes is composed of five panels in the gas flow direction. At the center of the upper header 1, a projection 7 for transmitting a horizontal force is provided. The distance between the casing 3 and the upper header 1 is about 1.2 m, and a heat insulating material 4 is adhered to the inner surface of the casing 3. The casing 3 is reinforced by an upper structural member 5 and an upper reinforcing member 6.

In the present embodiment, the truss surface in the gas flow direction is composed of an upper tubular horizontal member 10 and a horizontal member 15 at the position of the protrusion 7 provided on the header 1, and a gusset plate 11,
It is constituted by connecting with an oblique member 13 and a vertical member 9 via 12. The tubular horizontal member 10 located at the upper part of the truss surface penetrates the inner surface of the annular member 9 connected to the support hardware 8 which is mounted in the gas flow direction on the casing 3 and slides through this penetrating portion. As a result, the thermal expansion of the truss surface is not restricted. Further, in such a support structure, the tubular horizontal member 10 is rotatable in the axial direction with respect to the annular member 9. The upper gusset plate 11 is U-shaped so as to surround the periphery of the annular member 9, and is connected to the annular horizontal member 10 with a gap between the annular member 9. By adjusting the gap between the annular member 9 and the gusset plate 11, the direction of thermal expansion of the truss surface is defined. In this embodiment, the truss surface is shown in FIG.
As shown in the figure, the annular member 9 on the right side (gas downstream side)
The set plate 11 and the fixing member, and fixing the gap as 0 or very small amount, the other annular member 9 and Gasettopure
The seat 11 is slidably provided as a sliding member so that thermal expansion occurs to the left side (gas upstream side). FIG.
Indicates a stop (in a cold state), and at the support point on the moving side, the right side is taken as a thermal expansion allowance, and the gap on the left side is small.

The fixing point of the truss surface is selected so that the tube group and the truss surface thermally expand in the same direction according to the fixing point of the heat transfer tube group. As a result, deformation of the heat transfer tube group and generation of thermal stress can be prevented.

The truss surface configured as described above has projections 7
Across a two faces, Contact horizontally connected hardware 19 so as to surround the projection 7 Waso as shown in FIGS. 2 and 3
And is held . In addition, the truss surface connects the horizontal member 15 and the casing 3 by a diagonal member 16 and gusset plates 17 and 18 in a direction perpendicular to the gas flow. The oblique member 16 uses a member having a large width-to-thickness ratio so as to be easily deformed in a direction perpendicular to the gas flow, and takes a thickness direction in the gas flow direction to avoid generation of thermal stress. In addition,
In the present embodiment, the projection 7 is omitted as a simple projection, but a branch pipe connected to the upper header 1 may be used as the projection.

The truss surface for supporting the upper header having the above structure absorbs thermal expansion by sliding the upper annular horizontal member 10 with respect to the annular member 9 fixed to the casing 3. That is, when the members are directly welded, the temperature of the oblique member 13 and the horizontal member 15 and the like is close to 600 ° C. at the maximum. However, in the case of the configuration as in the present embodiment, generation of thermal stress can be minimized. This makes it possible to prevent thermal deformation of the truss member and welding cracks at the joint.

In this embodiment, two trusses are provided and connected to each other to support the upper header 1, but the truss surface is slidably supported in the gas flow direction and at the same time the gas flow direction is changed. It is rotatably supported on a shaft. That is, as shown in FIG. 5, the vertical member 14 and the oblique member 16 form a triangle with the casing 3 at the time of stop, but the connecting hardware 19 at the time of operation (at the time of inflow of hot gas).
Will thermally expand in the direction perpendicular to the gas flow. At this time, since the annular horizontal member 10 and the annular member 9 are rotatably connected to each other, the vertical member 14 does not undergo bending deformation but rotationally deforms in a C-shape. Therefore, even if the connecting metal 19 of the truss is thermally expanded, no out-of-plane bending deformation occurs on the truss surface. Further, since the truss surface is rotatably supported by the annular member 9, no bending moment is transmitted from the truss surface to the support metal 8 and the support portion to the casing 3, which is advantageous in designing the casing 3. .

When a horizontal force in the gas flow direction is applied from the heat transfer tube panel to the header supporting device, a force transmission path is first transmitted from the projection 7 to the connection hardware 19, passes through the horizontal member 15, and moves from the oblique member 16 to the connection member 19. It is transmitted to the upper part of the casing 3 via the fixed point of the truss surface (the right end in this embodiment). In the gas flow direction, the force is transmitted from the projection 7 through the horizontal member 15 to the casing 3 from the oblique member 16, but in this direction, the thermal stress of the oblique member 16 is absorbed by the deflection of the member itself. Only the oblique member that generates the tensile force with respect to the horizontal force shares the force. The fixing point of the truss surface is selected so that the tube group and the truss surface thermally expand in the same direction in accordance with the fixing point of the heat transfer tube group, so that deformation of the heat transfer tube group and generation of thermal stress can be prevented.

Thus, according to the upper header support device of this embodiment, the thermal stress in the truss plane in the gas flow direction can be suppressed. Further, since the truss surface in the gas flow direction is thermally expanded freely in the truss surface, the oblique member can be compressed and pulled, and the member can be downsized. Since the truss surface is rotatably supported by the casing, out-of-plane bending deformation can be prevented, and transmission of a bending moment to the casing can also be prevented. further,
The fixing point of the truss surface is selected so that the tube group and the truss surface thermally expand in the same direction in accordance with the fixing point of the heat transfer tube group, so that deformation of the heat transfer tube group and generation of thermal stress can be prevented.

Next, another embodiment of the present invention will be described with reference to FIG. The structure of the device is almost the same as that of the above embodiment, except that the supporting device supports three types of tube groups 1A to 1C by a single supporting device. A general exhaust heat recovery boiler often incorporates a plurality of heat transfer tube groups together in one casing. When such a tube group header is collectively supported, as shown in FIG. The truss becomes longer in the gas flow direction. Even in such a case, since the truss surface is slidably supported, the generation of thermal stress can be suppressed despite the fact that the horizontal member is considerably longer than in the first embodiment. . Further, by adopting the long support structure as in the present embodiment, saving and simplification of members can be realized.

FIG. 7 shows still another embodiment of the present invention. The configuration of this device is almost the same as that of the above-described embodiment, but this embodiment is a support device particularly in a case where the space for support is narrow, and the oblique member 13 is disposed between both the vertical members 14. This is different from the above embodiment. Also in the present embodiment, since the truss surface has a structure that allows free thermal expansion, the diagonal member 13 can be pulled and made effective both in compression and the size of the member can be reduced.

[0028]

As described above, according to the present invention, in a waste heat recovery boiler in which a heat insulating material is lined and an outer surface of a casing is kept close to room temperature, connection of heat transfer tubes in a gas flow area is achieved. By supporting the truss surface that supports the selected upper header slidably and rotatably in the gas flow direction, it is possible to minimize the generation of thermal stress and provide a highly reliable support device. Becomes

[Brief description of the drawings]

FIG. 1 is an elevational view of a support device for an upper header of an exhaust heat recovery boiler according to the present invention as viewed from a boiler side surface.

FIG. 2 is a view taken in the direction of arrows AA in FIG. 1;

FIG. 3 is a view taken in the direction of arrows BB in FIG. 1;

FIG. 4 is a view showing details of a support portion of the annular horizontal member.

FIG. 5 is a diagram showing deformation of a member in a direction perpendicular to the gas flow.

FIG. 6 is an elevation view showing an upper header supporting device of an exhaust heat recovery boiler according to another embodiment of the present invention.

FIG. 7 is an elevational view showing an upper header support device of an exhaust heat recovery boiler according to a third embodiment of the present invention.

FIG. 8 is a configuration diagram showing an example of a conventional exhaust heat recovery boiler.

FIG. 9 is a sectional view taken along the line CC of FIG. 8 ;

FIG. 10 is an enlarged sectional view showing details of a portion D in FIG. 9;

FIG. 11 is an enlarged sectional view showing details of a portion E in FIG. 9 ;

[Explanation of symbols]

 1: Upper header 1A: Upper header
Set A 1B: Upper header B 1C: Upper header
C2: Heat transfer tube 2A: Heat transfer tube A 2B: Heat transfer tube B 2C: Heat transfer tube C 3: Casing 4: Heat insulationLumber  5 Upper structural member 6 Upper reinforcement
Material 7: Projection 8: Support hardware 9: Annular member 10: Annular horizontal portion
Lumber 11,12,17,18… Gusset plate 13,16… Diagonal part
Material 14: Vertical member 15: Horizontal member 19: Connection hardware

Claims (3)

(57) [Claims] 1. An exhaust heat recovery boiler header feeder comprising a vertically connected header connected by a heat transfer tube to form a panel, wherein the panel is disposed in a flow area of exhaust gas. A truss that holds the upper header in the horizontal direction by combining two horizontal members to be arranged, a vertical member extending to both horizontal members, and an oblique member extending to both horizontal members outside the vertical members. An exhaust heat recovery system is characterized in that one point of the truss is fixed to a ceiling plate via a fixing member, and another point is slidably provided on the ceiling plate via a sliding member along a gas flow direction. Boiler header support device. 2. A tubing is used for a horizontal member on the upper part of the truss, and the horizontal member is penetrated by an annular member provided on a ceiling plate, so that it is slidable in the longitudinal direction and rotatable in the axial direction. 2. The truss structure according to claim 1, wherein two supporting trusses are provided, and the lower horizontal member constituting the lower part of the two trusses is connected so as to surround the protrusion of the upper header. A header support device for an exhaust heat recovery boiler. 3. The fixing point where the fixing member of the truss is located is set to coincide with or close to the fixing point of the heat transfer tube panel, and the displacement direction of the truss during operation is set to the displacement direction of the heat transfer tube panel. The header support device for the exhaust heat recovery boiler according to claim 1, wherein the headers are matched.