JPH04313603A - Supporting apparatus for header in exhaust-heat recovery boiler - Google Patents

Abstract

PURPOSE:To make a supporting apparatus for headers in an exhaust-heat recovery boiler capable of supporting an upper header effectively against forces applying to it sideways and capable of also minimizing the thermal stress produced in the supporting members. CONSTITUTION:A plane of a truss in the direction of the flow of the gas is formed by joining, by means of slanting members 13 and vertical members 9 and with the help of gusset plates 11, 12, a ring-shaped horizontal member 10 at an upper position and a horizontal member 15 positioned at projections 7 formed respectively from headers 1. The ring-shaped horizontal member 10 is axially rotatable in relation to ring members 9 which are connected with supporting metal fittings 8.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

[Industrial Application Field] The present invention relates to an exhaust heat recovery boiler.
In particular, the present invention relates to a support device for horizontal force of a header used by being incorporated into a large-scale waste heat recovery boiler.

0002

2. Description of the Related Art Generally, a combined cycle power plant uses an exhaust heat recovery boiler that uses exhaust gas from a gas turbine or the like as a heat source to generate driving steam for a steam turbine and hot water for process use.

FIG. 8 shows an example of a conventional exhaust heat recovery boiler. The exhaust heat recovery boiler shown in this figure is a so-called natural circulation boiler in which a steam drum is placed at the top of the equipment and heat transfer tubes are installed vertically, and the exhaust gas from a gas turbine etc. is sent to the exhaust heat recovery boiler 41. first flows into the superheater 42
, a high-pressure evaporator 43, and a denitrification device 44, where the nitrogen oxides contained therein are removed. The exhaust gas exiting the denitrification device 44 is sent to a high-pressure economizer 45, a low-pressure evaporator 46, and a low-pressure economizer 4.
7 in order, and the internal fluid in each heat exchanger tube undergoes heat exchange.

Compared to a forced circulation type waste heat recovery boiler, a natural circulation type waste heat recovery boiler as shown in the figure has the advantage that a circulation pump is not required and the power required for the plant can be reduced. The height to the top can be kept low, and the boiler duct can be made into a self-supporting structure, eliminating the need for supporting steel frames. It is thought that this method will be adopted.

FIG. 9 shows a sectional view taken along line CC in FIG. Reference numeral 55 in the figure indicates a heat transfer tube, which is arranged vertically and connected to the 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 atmospheric temperature. The loads of the panels, such as the heat exchanger tubes 55 and 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 tubes 55 and the upper header 54 are displaced upward in the vertical direction from the support point of the lower header 56 as a starting point.

[0006] 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 a finned heat exchanger tube, the fins act as a load mass, but do not increase the rigidity of the tube, and in order to prevent the heat exchanger tube 55 from buckling and make it self-supporting, the displacement of the upper header 54 must be restrained. . For this reason, a support device is installed to restrain horizontal displacement of the upper header 54. This support device also supports the heat exchanger tubes, which are the heaviest items, even when a horizontal force such as an earthquake force acts on the waste heat recovery boiler.
It also has the function of supporting the load of panels such as 5 and transmitting it to the casing 51. In terms of strength, the members constituting the support device are designed to withstand horizontal forces during an earthquake.

FIGS. 10 and 11 show an example of a horizontal force transmission support structure for an upper header 54 of a conventional exhaust heat recovery boiler. In the example shown in FIG. 10, the upper header 54 is provided with a protruding lug 62 in the center of the upper header 54, which is supported by a bracket 61 provided at the upper part of the casing 51, to absorb the horizontal force acting perpendicularly to the gas flow. It is structured as follows. Further, in the example shown in FIG. 11, the horizontal force in the gas flow direction is supported by sandwiching the protruding member 65 provided at the end of the upper header 54 with a supporting member 66 attached to the inner surface of the casing (in actual practice (See Publication No. 141503/1983).

[0008]

[Problem to be solved by the invention] In recent years, combined cycle power plants have tended to become larger due to the increase in the capacity of gas turbines, and as a result, larger exhaust heat recovery boilers are being planned than before. It has become to. Currently, the height and width of the gas passage exceeds 10m,
There are also exhaust heat recovery boilers with a total length of 30 m or more.

[0009] In such a large-scale waste heat recovery boiler, the width of the gas passage section is long, so the header cannot be composed of a single header in the width direction, and the header is divided into multiple pieces in the width direction of the gas passage section. There is a need to. In addition, during inspections and repairs, it is necessary to access the upper header, and in order to repair leaking pipes, measures such as lifting and moving the pipe bundle to secure space are required. Sufficient space is required between the crane rail and the casing 51 in order to install a crane rail and a lifting trolley.

In the support structure of the upper header 54 as shown in FIG. 10, it is necessary to make the lug 62 attached to the upper header 54 or the bracket 61 on the casing 51 side long and large. However, when a horizontal force acts on the upper header 54, because the moment arm is longer in the former case, excessive bending stress is generated at the root of the lug 62, that is, at the welded part with the upper header 54, which is a pressure-resistant part. ,
There are concerns that serious defects such as weld cracks may occur. Furthermore, in the latter case as well, the bending stress must be shared by the bracket 61, resulting in a disadvantage that the member becomes too large. In addition, when the upper header 54 is divided into multiple parts in the width direction, the upper header 54
It is virtually impossible to support the end of the casing 51 from the casing 51 side.

Furthermore, in the exhaust heat recovery boiler shown in FIG. 9, a heat insulating material 52 is pasted on the inner surface of the casing 51, so there is a large temperature difference between the temperature of the casing 51 and the gas temperature inside. When connecting the internal structural members of the casing 51 to the casing 51, a problem arises as to how to absorb the difference in thermal expansion between the members due to the temperature difference.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a header support device that can effectively support the forces acting on the upper header in the longitudinal and lateral directions and that can keep the thermal stress generated in the support member to a minimum. With the goal. [Structure of the invention]

[0013]

[Means for Solving the Problems] In order to achieve the above object, the present invention connects headers arranged above and below with heat transfer tubes to form a panel, and places this panel in a flow area of exhaust gas. In the header support device for an exhaust heat recovery boiler, two horizontal members arranged above and below, a vertical member that spans both horizontal members, and a diagonal member that spans both horizontal members outside the vertical members are combined. The present invention is characterized in that a truss is formed to support the upper header, one point of the truss is fixed to the ceiling plate, and the other point is provided on the ceiling plate so as to be slidable along the gas flow direction. In addition, a pipe material is used for the horizontal member at the top of the truss, and the horizontal member is passed through an annular member attached to the ceiling plate, thereby supporting the truss so as to be slidable in the longitudinal direction and rotatable in the axial direction. It is characterized by having two sides, and connecting the lower parts of the two sides of the truss so as to surround the protrusion of the upper header or the branch pipe. Furthermore, the fixed point of the truss is arranged to match or as close as possible to the fixed point of the heat exchanger tube panel, and the direction of displacement of the truss during operation is made to coincide with the direction of displacement of the heat exchanger tube panel.

[0014]

[Operation] According to the present invention constructed as described above, the upper header support truss is supported slidably in the gas flow direction, and the members constituting the truss are freely thermally expanded, thereby causing the members to The occurrence of thermal stress inside the tank is suppressed.

[0015] Furthermore, when the same truss is provided on two sides and connected to support the upper header, the truss surface can be slidably supported in the gas flow direction, and at the same time, the truss surface can be rotated around the gas flow direction. Therefore, even if the connecting hardware of the two truss surfaces thermally expands, out-of-plane bending deformation does not occur on the truss surface, and no bending moment is transmitted to the support portion or to the casing.

Furthermore, since the fixing point of the support device is made to coincide with the fixing point of the heat transfer tube group, or is selected as close as possible, the difference in displacement due to thermal expansion between the two can be minimized, and thermal stress due to restriction of displacement can be minimized. The occurrence of is suppressed.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

In FIGS. 1 to 3, an upper header 1 is arranged perpendicular to the gas flow, and a plurality of heat exchanger tubes 2 are connected to form a panel. In this embodiment, three rows of heat exchanger tubes 2 are connected to one stage of panels, and the heat exchanger tube group consists of five stages of panels in the gas flow direction. A projection 7 for transmitting horizontal force is provided at the center of the upper header 1. The distance between the casing 3 and the upper header 1 is approximately 1.2 m, and a heat insulating material 4 is pasted on 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 this embodiment, the truss surface in the gas flow direction connects the upper tubular horizontal member 10 and the horizontal member 15 at the position of the protrusion 7 provided on the header 1 diagonally through the gusset plates 11 and 12. It is constructed by connecting with a member 13 and a vertical member 9. The tubular horizontal member 10 located at the upper part of the truss surface passes through the inner surface of the annular member 9 connected to the supporting hardware 8 attached to the casing 3 in alignment with the gas flow direction, and slides through this penetration part. This prevents the thermal expansion of the truss surface from being restricted. Moreover, 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 annular member 9, and is connected to the annular horizontal member 10 with a gap between the annular member 9 and 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 determined. In this embodiment, as shown in FIG. 4, the truss surface has a fixed gap on the right side (gas downstream side) of zero or a very small amount, so that thermal expansion occurs toward the left side (gas upstream side). Also,
FIG. 4 shows the state at rest (in a cold state), and at the support point on the moving side, the right side is taken as the thermal expansion allowance, and the gap on the left side is small.

The fixed points on the truss surface are selected in accordance with the fixed points on the heat exchanger tube group so that the tube group and the truss surface thermally expand in the same direction. This can prevent deformation of the heat exchanger tube group and generation of thermal stress.

The truss surface configured as described above has a protrusion 7
As shown in FIGS. 2 and 3, they are connected by a connecting metal fitting 19 so as to surround the protrusion 7. As shown in FIGS. Further, in the direction perpendicular to the gas flow, this white surface connects the horizontal member 15 and the casing 3 by a diagonal member 16 and gusset plates 17 and 18. Diagonal member 16
In order to easily deform in the direction perpendicular to the gas flow, a member with a larger width-to-thickness ratio is used, and the plate thickness is oriented in the gas flow direction to avoid the generation of thermal stress.

In the truss surface for supporting the upper header constructed as described above, thermal expansion is absorbed by the upper annular horizontal member 10 sliding against the annular member 9 fixed to the casing 3. In other words, in the case of direct welding, the temperature of the diagonal member 13, horizontal member 15, etc. reaches a maximum of nearly 600°C, so the difference in thermal expansion between them causes excessive thermal stress in the compression direction to the casing 3, which is at approximately room temperature. However, if the structure of this embodiment is adopted, the occurrence of thermal stress can be suppressed to a minimum. This makes it possible to prevent thermal deformation of the truss member and weld cracking at the joint.

Furthermore, in this embodiment, two truss surfaces are provided and these are connected to support the upper header 1, but the truss surface supports the upper header 1 slidably in the gas flow direction and at the same time supports the gas flow direction. Rotatably supported on the shaft. That is, as shown in FIG. 5, when stopped, the vertical member 14 and the diagonal member 16 form a triangle with the casing 3, but during operation (when hot gas flows in), the connecting hardware 19
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, the vertical member 14 is not bent and deformed, but is rotationally deformed in a V-shape. Therefore, even if the connecting hardware 19 of the truss expands thermally, no out-of-plane bending deformation occurs on the truss surface. Furthermore, since the truss surface is rotatably supported by the annular member 9, no bending moment is transmitted from there to the support hardware 8 and the support portion of the casing 3, which is advantageous in terms of the design of the casing 3. .

When a horizontal force in the gas flow direction is applied to the header support device from the heat exchanger tube panel, the force is first transmitted from the protrusion 7 to the connecting metal fitting 19, and then from the horizontal member 1.
5 and is transmitted from the diagonal member 16 to the upper part of the casing 3 via the aforementioned fixed point on the truss surface (in this embodiment, the right end). In the case of the gas flow direction, the force is transmitted from the protrusion 7 through the horizontal member 15 and from the diagonal member 16 to the casing 3, but in this direction, the thermal stress of the diagonal member 16 is absorbed by the deflection of the member itself. , only the diagonal member that generates the tensile force will share the force with respect to the horizontal force. The fixing points on the truss surface are selected in accordance with the fixing points on the heat exchanger tube group so that the tube group and the truss surface will thermally expand in the same direction, thereby preventing deformation of the heat exchanger tube group and generation of thermal stress.

Thus, according to the upper header support device of this embodiment, thermal stress within the truss plane in the gas flow direction can be suppressed. In addition, since the truss surface in the gas flow direction is allowed to thermally expand freely within the truss surface, the diagonal member can be compressed and tensioned, and the member can be made smaller. Since the truss surface is rotatably supported with respect to the casing, out-of-plane bending deformation can be prevented, and bending moments can also be prevented from being transmitted to the casing. moreover,
The fixing points on the truss surface are selected so that the tube group and the truss surface thermally expand in the same direction in accordance with the fixing points on the heat exchanger tube group, thereby preventing deformation of the heat exchanger tube group and generation of thermal stress.

Next, another embodiment of the present invention will be described with reference to FIG. The configuration of the device is almost the same as that of the previous embodiment, except that the support device supports three types of tube groups, heat transfer tube groups 1A to 1C, with a single support device. In a typical waste heat recovery boiler, multiple heat transfer tube groups are often assembled into one casing, and when supporting the header of such a tube group all at once, as shown in Figure 6, The truss becomes longer in the direction of gas flow. Even in such a case, since the truss surface is slidably supported, the generation of thermal stress can be suppressed even though the horizontal member is considerably longer than in the first embodiment. . Furthermore, by employing a long support structure as in this embodiment, it is possible to save and simplify the number of members.

FIG. 7 shows yet another embodiment of the invention. The configuration of this device is almost the same as that of the above embodiment, but in this embodiment, the support device is used especially when the space for support is narrow, and the diagonal member 13 is arranged between both vertical members 14. This embodiment differs from the above embodiment in this point. In this embodiment as well, the truss surface has a structure that allows free thermal expansion, so the diagonal member 13 can be stretched and compressed, and the member can be made smaller.

[0028]

As explained above, according to the present invention, in an exhaust heat recovery boiler in which the outer surface of the casing is kept close to room temperature by being lined with a heat insulating material, heat exchanger tubes can be connected in a gas flow area. By supporting the truss surface that supports the upper header so that it can slide and rotate freely in the gas flow direction, it is possible to minimize the occurrence of thermal stress and provide a highly reliable support device. becomes.

[Brief explanation of the drawing]

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

FIG. 2 is a view taken along the line A-A in FIG. 1;

FIG. 3 is a BB arrow view in FIG. 1.

FIG. 4 is a diagram showing details of the support part of the annular horizontal member.

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

FIG. 6 is an elevational view showing an upper header support 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 a waste 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.

9 is a sectional view taken along line CC in FIG. 9. FIG.

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

FIG. 11 is an enlarged sectional view showing details of section E in FIG. 10;

[Explanation of symbols]

1...Upper header
1A...Upper header A 1B...Upper header B
1C...Upper header C 2...Heat transfer tube
2A... Heat exchanger tube A 2B... Heat exchanger tube B
2C... Heat exchanger tube C 3... Casing
4...Heat insulation 5...Superstructure members
6... Upper reinforcing member 7... Protrusion
8... Support hardware 9... Annular member
10... Annular horizontal member 11, 12, 17, 18... Gusset plate 1
3, 16...Diagonal member 14...Vertical member
15...Horizontal member 19...Connection hardware

Claims (3)

[Claims] Claim 1: A header support device for an exhaust heat recovery boiler, in which a heat transfer tube connects the headers disposed above and below to form a panel, and this panel is placed in an exhaust gas flow area. A truss for supporting the upper header is formed by combining the two horizontal members arranged, a vertical member spanning both horizontal members, and a diagonal member extending outside the vertical members and spanning both horizontal members, and A pipe header support device for an exhaust heat recovery boiler, characterized in that one point of the truss is fixed to a ceiling plate, and the other point is slidably provided on the ceiling plate along the gas flow direction. 2. A pipe material is used for the horizontal member at the top of the truss, and the horizontal member is supported so as to be slidable in the longitudinal direction and rotatable in the axial direction by passing through an annular member provided on the ceiling plate. 2. The exhaust heat recovery boiler according to claim 1, characterized in that two trusses are provided on two sides, and the lower parts of the two truss are connected to surround the protrusion of the upper header or the branch pipe. Header support device. 3. The fixing point of the truss is arranged to match or as close as possible to the fixing point of the heat exchanger tube panel, and the direction of displacement of the truss during operation is made to coincide with the direction of displacement of the heat exchanger tube panel. A header support device for an exhaust heat recovery boiler according to claim 1.