JP2003222304A - Support structure of heat transfer tube panel and exhaust heat recovery boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a support structure of a heat transfer tube panel which can prolong the life of the heat transfer tube support by decreasing a thermal stress (temperature difference) generated at a heat transfer tube and the heat transfer tube support on the rear flow side of a duct burner, especially the thermal stress (temperature difference) at a welded part. <P>SOLUTION: In this support structure, between adjacent vibration proof supports 22, 23; 25, 26; 28, 29 made of a honeycomb structure for welding and fixing each of the heat transfer tubes 31, arranged with their longitudinal direction crossing the pipe axis direction of the heat transfer tube 31 in a gas passage and bundling a plurality of the heat transfer tubes 31, plate-state supports 21, 24; 27, 30 are arranged in a space where the heat transfer tube 31 is not arranged, and the vibration proof supports 22, 23; 25, 26; 28, 29 corresponding to a portion of a gap between the vibration proof support and the heat transfer tube 31 are welded and connected to contact portions 32a and 32b of the plate- state supports 21, 24; 27, 30. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for a heat transfer tube which is arranged in a gas passage through which hot gas flows to generate steam, and more particularly to an exhaust structure for recovering heat from a gas turbine exhaust gas to generate steam. Regarding heat recovery boilers. Further, the present invention relates to a heat transfer tube support structure capable of reducing the thermal stress generated in the heat transfer tube support installed in the heat transfer tube panel, extending the fatigue life of the heat transfer tube support, and increasing the allowable number of start-stop operations.

[0002]

2. Description of the Related Art A combined cycle power plant is
Power is generated by the gas turbine, and heat in the exhaust gas discharged from the gas turbine is recovered by an exhaust heat recovery boiler to generate steam, and power is also generated by the steam turbine. In general, a combined cycle power plant has characteristics that it has high power generation efficiency and high load responsiveness, and can cope with a sudden increase in power demand.

FIG. 4 shows an example of the device configuration of a horizontal exhaust heat recovery boiler. The exhaust heat recovery boiler of FIG. 4 is a horizontal type natural circulation boiler in which a duct burner (auxiliary burner) is arranged at the boiler inlet, and heat transfer tubes are arranged in the vertical direction. , Duct burner 13,
Superheater 3, high pressure evaporator 4, denitration device 5, high pressure economizer 6,
A low pressure evaporator 7 and a low pressure economizer 8 are arranged.

Exhaust gas 1 from a gas turbine (not shown) flows into a casing 2, and a flame 14 of a duct burner 13
The gas temperature is raised by the superheater 3, high-pressure evaporator 4
After passing through and heat exchange, it enters the denitration device 5, and nitrogen oxides in the exhaust gas are removed. Further, the exhaust gas 1 sequentially passes through the high-pressure economizer 6, the low-pressure evaporator 7, and the low-pressure economizer 8, undergoes heat exchange with the internal fluid in the heat transfer tube, the gas temperature decreases, and the gas is discharged from a stack (not shown). To be done.

FIG. 5 shows the temperature change of the exhaust gas 1 from the inlet to the outlet of the exhaust heat recovery boiler. In the case of the temperature change curve 61 of the exhaust heat recovery boiler without the duct burner 13, the temperature of the exhaust gas 1 discharged from the gas turbine is heat-exchanged by the heat transfer tubes from the superheater 3 to the low pressure economizer 8, The temperature gradually decreases. On the other hand, in the case of the temperature change curve 60 of the exhaust heat recovery boiler with the duct burner 13, the exhaust gas temperature sharply rises due to the duct burner 13, and compared with the case without the duct burner 13, the superheater 3 to the low-pressure economizer 8
Due to the large amount of heat exchange by each heat transfer tube up to, the temperature of the exhaust gas drops sharply. Generally, the exhaust gas temperature of the gas turbine is about 600 ° C., and the temperature of the exhaust gas 1 is raised to about 700 to 1000 ° C. by the duct burner 13.

Detailed structures of the duct burner 13 and the superheater 3 shown in FIG. 4 are shown in FIG. In FIG. 6, three-stage burners 131a, 131b, 131c are attached to the duct burner 13, and the fuel burns in each burner to form flames 132a, 132b, 132c. The superheater 3 includes an upper head 120 and a lower head 121.
It is composed of heat transfer tube panels connected by rows of heat transfer tubes 123a, 123b, 123c, and is suspended from the casing 2 by a heat transfer tube suspension support 122. In this heat transfer tube panel, in order to prevent the heat transfer tube 123 from vibrating due to the flow of the exhaust gas 1, the heat transfer tube supports 124 a to 12 a.
4f is welded and connected.

[0007]

In the above-mentioned prior art, the heat transfer tube group arranged in the gas flow path away from the duct burner 13 has a structure in which fins are wound around the outer circumference of the tube in order to enhance heat absorption efficiency. Used, but duct burner 13
Since the heat transfer tubes 123a to 123c in the vicinity of are directly subjected to radiant heat from the flame, heat transfer tubes (bare tubes) having no fins wound around their outer circumferences are used.

Usually, the heat transfer tubes 123a to 123c and the headers 120 and 121 are welded by automatically welding on a complicated curved surface based on the heat transfer tube with fins. In order to reduce the cost, the welding of the heat transfer tube and the heat transfer tube is performed automatically according to the same procedure as the heat transfer tube with fins (welding coordinate position, overlay thickness, etc.).

Therefore, since the heat transfer tubes 123a to 123c near the duct burner 13 have no fins, the duct burner 1
Since the interval between adjacent heat transfer tubes of the heat transfer tube group close to 3 becomes relatively large and there is no member in the interval portion, there is a problem that the heat transfer tube is easily thermally deformed.

Further, the heat transfer tube supports 124a to 124f
Despite receiving radiant heat from the flame, since the fluid flows in the heat transfer tubes 123a to 123c, a difference occurs between the metal temperatures of the heat transfer tubes 123a to 123c, and the heat transfer tube support 124a
~ 124f and the heat transfer pipes 123a to 123c, excessive thermal stress occurs, the welded parts of both are fatigue-damaged by the start and stop of the plant, and in some cases, the welded parts may be broken. The problem is to prevent deformation of the heat transfer tube on the downstream side of the duct burner, and to reduce the thermal stress (temperature difference) generated between the heat transfer tube and the heat transfer tube support, especially the thermal stress (temperature difference) of the welded part, A heat transfer tube and a support structure for a heat transfer tube panel that increases the life of the heat transfer tube support, and an exhaust heat recovery boiler equipped with the support structure.

[0011]

The above-mentioned problems of the present invention can be solved by the following means. That is, the heat transfer tubes arranged in the hot gas flow path, the longitudinal direction is arranged orthogonal to the tube axis direction of the heat transfer tubes, and each heat transfer tube is housed inside the hole so as to bundle a plurality of heat transfer tubes. A heat transfer tube support structure having a vibration proof support for fixing a contact portion with each heat transfer tube, wherein a plate-shaped support is arranged in a space in which a heat transfer tube between two adjacent vibration proof supports is not arranged, This is a heat transfer tube support structure for welding and connecting the abutting portions of the vibration support and the plate-shaped support corresponding to the portion having the gap between the vibration support and the heat transfer tube.

In the heat transfer tube support structure of the present invention, a heat transfer tube header for collecting the fluid in each heat transfer tube is provided at an end of the plurality of heat transfer tubes, and is close to the heat transfer tube header among the vibration isolation supports. Anti-vibration support other than the part's anti-vibration support,
It is possible to use a structure in which two bent plates are attached to each other in a direction orthogonal to the tube axis of the heat transfer tube, and the heat transfer tube is arranged in the obtained hole portion.

Further, the cross-sectional shape of the hole portion of the vibration isolation support obtained by pasting the two bent plates in a direction orthogonal to the heat transfer tube tube axis is hexagonal (honeycomb shape), quadrangular () square shape, etc. It is possible to weld and fix the contact portion between the vibration-proof support and the heat transfer tube.

Further, heat exchange with the hot gas is promoted by arranging the portions supporting the heat transfer tubes in a zigzag pattern in the flow direction of the hot gas.

Further, the heat transfer tube support structure may be provided in a gas passage of an exhaust heat recovery boiler in which a heat transfer tube group for recovering heat from a gas turbine combustion exhaust gas and generating steam is arranged.

[0016]

[Operation] By disposing the plate-shaped support in the space where there is no heat transfer tube between two adjacent vibration isolation supports arranged on the downstream side of the duct burner, thermal deformation of the heat transfer tube is prevented, and the vibration isolation support and heat transfer tube are also provided. It is possible to more firmly prevent thermal deformation of the heat transfer tube by welding and connecting the abutting portions of the vibration-proof support and the plate-shaped support corresponding to the portion having the gap between the heat-transfer tube and the plate-shaped support.

Further, during operation of the exhaust heat recovery boiler, the internal fluid (steam) flows through the heat transfer tube, so that it is cooled, but the vibration isolating support is not cooled, so there is a large temperature difference between the heat transfer tube and the vibration isolating support. Is occurring. Since the vibration-isolating support is cooled by the heat-transfer tube at the part where the vibration-isolating support and the heat-transfer tube are in contact with each other, the temperature of the vibration-isolating support locally drops, and a difference in thermal expansion occurs at this part, which causes locally excessive thermal stress. Occurs.

In the heat transfer tube support structure of the present invention, since no welded portion is provided between the vibration isolation support and the plate-shaped support at the contact position between the vibration isolation support and the heat transfer tube, excessive heat stress is applied to the welded portion. Does not occur. Therefore, the start and stop of the plant will not cause fatigue damage to the welded part, causing the welded part to break or reducing the allowable number of start and stop.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a heat transfer tube support structure for a heat transfer tube panel according to the present invention will be described with reference to the drawings.

[0020]

1 is a sectional view of a heat transfer tube panel according to an embodiment of the present invention, in which a heat transfer tube 31 has an exhaust gas 33 as shown in FIG.
Are arranged in a zigzag pattern in the flow direction of the heat transfer tubes, and the heat transfer tubes are reinforcement plates 21 and 30, heat transfer tube support plates 22, 23, 25, and 2.
It is supported by a heat transfer tube support having a structure in which a total of ten plates 6, 28, 29 and space plates 24, 27 are joined.
Ten plate-like members 21 to 21 that constitute the heat transfer tube support
Of the 30, heat transfer tube support plates 22, 23, 25, 26, 2
Six members 8 and 29 are bent plates, and hexagonal holes are created by two adjacent heat transfer tube support plates, and the heat transfer tubes 31 are accommodated in the holes. It is a structure for fixing 31. Each heat transfer tube 31 is a plate-shaped member 22, 2
There are 3 and 6 contact points, and no gap can be made at each contact point. Adjacent plate-shaped members are joined to each other by spot welding, and the welding position is provided at a position sufficiently distant from the position where the heat transfer tube 31 and the plate-shaped members are in contact with each other. In the embodiment of FIG. 1, the plate member 22 and the reinforcing plate 2
The welded portions for joining 1 are provided at two places of the welded portions 32a and 32b, but it is not always necessary to provide at two places, and for example, only the welded portion 32a may be provided.

During operation of the exhaust heat recovery boiler, the temperature of the heat transfer tube 31 and the heat transfer tube support of the heat transfer tube 31 rises due to the high temperature exhaust gas 33. At this time, the internal fluid (vapor) is flowing through the heat transfer tube 31, so that the heat transfer tube 31 is cooled, but the heat transfer tube support composed of the 10 plate-shaped members 21 to 30 is not cooled. A large temperature difference occurs in the heat pipe support. Each plate member 22 of the heat transfer tube support,
The plate-shaped members 22, 23, 25, 26, 28, 29 are cooled by the heat transfer tubes 31 at the portions where 23, 25, 26, 28, 29 are in contact with the heat transfer tubes 31, but in the heat transfer tube support structure according to the present invention, , Adjacent plate members 22, 23, 25, 2
Welds 32a, 32b for joining 6, 28, 29
The heat transfer tube 31 and the plate members 22, 23, 25, 26, 2
Since they are arranged at positions sufficiently separated from the contact portions of 8, 29, the welding portions 32a, 32b of the plate-shaped members 22, 23, 25, 26, 28, 29 with the heat transfer tubes 31 are cooled from the heat transfer tubes 31. It will not be done.

Therefore, as in the conventional heat transfer tube support structure shown in FIGS. 7 and 8 which will be described later, adjacent plate members 2 are provided.
Weld 3 for joining 2, 23, 25, 26, 28, 29
There is no occurrence of excessive thermal stress due to the temperature difference between 2a and 32b.

FIG. 2 shows a change in metal temperature in the cross section taken along the line AA 'in FIG. Since there is a space between the heat transfer tube 31 and the plate member 22 on the AA ′ line, the plate member 22 and the welded portion 32 a between the plate member 22 and the plate member 21 are connected to each other by the heat transfer tube 3.
It is not cooled from 1. Therefore, the temperature difference ΔT generated between the portions on the line AA ′ where the welded portion 32a contacts the plate-shaped member 22 and the plate-shaped member 21 is ΔT of the conventional structure shown in FIG.
It becomes significantly smaller than. Therefore, the thermal stress generated by the temperature difference ΔT is also greatly reduced, and the fatigue damage of the welded portion caused by the start and stop of the plant is smaller than that of the conventional structure.

FIG. 3 shows a cross-sectional view of a heat transfer tube panel according to another embodiment of the present invention. In this embodiment, the heat transfer tube support plates 41 and 4 are used.
The shapes of 2, 44, 45, 47 and 48 are such that the holes for accommodating the heat transfer tubes 50 are quadrilateral. This embodiment is characterized in that the number of welded parts is smaller than that of the embodiment of FIG. Other functions and effects of this embodiment are similar to those of the embodiment shown in FIG.

[0025]

[Comparative Example] FIG. 7A is a plan view of a cross section taken along the line BB ′ of FIG.
Shown in. The heat transfer tube support 124 is formed by welding a plurality of plate-shaped members by welding. In this example, the reinforcing plate 140,
149, heat transfer tube support plates 141, 142, 144, 145 that are bent to accommodate the heat transfer tube 123,
147, 148, heat transfer tubes 123a and 123b and 123
Space plates 143, 14 that secure the space between b and 123c
It is composed of 6 sheets in total. These 10 plates are joined by welding adjacent plates at the welded portion 150. The heat transfer tube 123 and the heat transfer tube support plates 141, 142,
The 144, 145, 147, and 148 are designed to come into contact with each other without a gap.

FIG. 7B shows a metal temperature change curve 153 of each plate of the heat transfer tube support 124. The exhaust gas 152 is cooled by the heat transfer tube 123 and the temperature thereof gradually decreases. Further, since the reinforcing plate 140 and the heat transfer tube supporting plate 141 receive radiant heat from the flame, the temperature of the metal forming them becomes higher on the upstream side of the flow of the exhaust gas. Also,
FIG. 7B also shows a metal temperature curve 154 of the heat transfer tube 123. While steam is flowing inside the heat transfer tube 123 to be cooled, the heat transfer tube support 124 is not cooled, so that the metal temperature is higher than that of the heat transfer tube 123.

FIG. 8 (a) is an enlarged view of the reinforcing plate 140 and the heat transfer tube supporting plate 141 in the vicinity of the welded portion 150 shown in FIG. 7 (a), and FIG. 8 (b) is shown in FIGS. a) C-
The change of the metal temperature of the C'line cross section is shown. Since the heat transfer tube 123a is cooled by steam as described above, the metal temperature thereof is low, and therefore the heat transfer tube support plate 141 and the reinforcing plate 140 are used.
Also, since the heat transfer tube support plate 141 and the heat transfer tube 123a are also cooled from the contact part, the metal temperature of the cross section along the line CC 'is as shown in FIG. A difference ΔT occurs.

A metal temperature curve 154 of the heat transfer tube 123 is also shown in FIG. 7 (b). While steam is flowing inside the heat transfer tube 123 to be cooled, the heat transfer tube support 1
Since 24 is not cooled, the metal temperature is higher than that of the heat transfer tube 123.

When a large temperature difference ΔT occurs in the welded portion 150 of the heat transfer tube support 124, an excessive thermal stress is generated.
0 is subject to fatigue damage, the welded part 150 may be broken, and the allowable number of start-stops is reduced.

[0030]

According to the heat transfer tube support structure of the present invention, the heat stress (temperature difference) generated in the heat transfer tube support of the heat transfer tube panel on the downstream side of the duct burner, especially the heat stress (temperature difference) of the welded portion is reduced. Thus, the fatigue life of the heat transfer tube support can be increased.

[Brief description of drawings]

FIG. 1 is a plan view of a heat transfer tube panel according to an embodiment of the present invention.

FIG. 2 is a diagram showing changes in metal temperature in a cross section taken along the line AA ′ of FIG.

FIG. 3 is a plan view of a heat transfer tube panel according to another embodiment of the present invention.

FIG. 4 is a diagram showing a device configuration of a horizontal exhaust heat recovery boiler.

FIG. 5 is a diagram showing a comparison of changes in exhaust gas temperature with and without a duct burner.

FIG. 6 is a side view of a detailed structure of a duct burner and a heat transfer tube panel.

7 is a plan view of the BB 'plane of FIG. 6 (FIG. 7 (a)).
FIG. 9 is a diagram (FIG. 7 (b)) showing the heat transfer tube support of each part and the metal temperature of the heat transfer tube in the plan view.

8 is an enlarged view (FIG. 8 (a)) near the welded portion of the reinforcing plate and the heat transfer tube supporting plate of FIG. 7 (a), and FIG. 7 (a) and FIG.
It is a figure (FIG.8 (b)) which shows the metal temperature of CC 'line cross section of FIG. 7 of (a).

[Explanation of symbols]

1 Exhaust gas flow direction 2 Casing 3 Superheater 4 High-pressure evaporator 5 Denitration device 6 High-pressure economizer 7 Low-pressure evaporator 8 Low-pressure economizer 13 Duct burner 14 Flame 21, 30 Reinforcing plate 22, 23, 25, 26, 28, 29 Heat transfer tube support plates 24, 27 Space plates 31, 50, 12
3 Heat Transfer Pipes 32a, 32b Welded Part 33 Exhaust Gas 41, 42, 44, 45, 47, 48 Heat Transfer Pipe Support Plates 60, 61 Temperature Change Curve 120 of Exhaust Heat Recovery Boiler 120 Upper Pipe Head 121 Lower Pipe Head 122 Heat Pipe Lifting Support 124 Heat Transfer Tube Supports 131a to 131c Burners 132a to 132
c Flame 140, 149 Reinforcement plates 141, 142, 144, 145, 147, 148 Heat transfer tube support plates 143, 146 Space plate 150 Welds 153, 154 Change curves of metal temperature

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Kawahara             Babcock Hitachi 6-9 Takaracho, Kure City, Hiroshima Prefecture             Kure Office Co., Ltd.

Claims (5)

[Claims] 1. A heat transfer tube arranged in a hot gas passage and a heat transfer tube whose longitudinal direction is arranged orthogonally to the tube axis direction of the heat transfer tube, and each heat transfer tube is provided inside a hole so as to bundle a plurality of heat transfer tubes. A heat transfer tube support structure having an anti-vibration support for accommodating and fixing the contact portion with each heat transfer tube, wherein a plate-shaped support is arranged in a space between two adjacent anti-vibration supports where no heat transfer tube is placed. Then, the heat transfer tube support structure is characterized in that the abutting parts of the vibration support and the plate-like support corresponding to the part having the gap between the vibration support and the heat transfer tube are connected by welding. 2. A heat transfer tube near the plurality of heat transfer tubes, in which fluid in each heat transfer tube collects, is provided at an end portion of the heat transfer tube,
The anti-vibration support other than the anti-vibration support near the heat transfer tube is a structure in which two bent plates are pasted together in the direction orthogonal to the tube axis of the heat transfer tube, and the heat transfer tube is placed in the resulting hole. The heat transfer tube support structure according to claim 1, wherein: 3. The heat transfer tube support structure according to claim 1, wherein the portions of the vibration isolating support that support the heat transfer tube are arranged in a staggered manner with respect to the flow direction of the hot gas. 4. A cross-sectional shape of a hole portion of a vibration-proof support obtained by laminating two bent plates in a direction orthogonal to a heat transfer tube tube axis is hexagonal or quadrangular. The heat transfer tube support structure according to any one of 3 above. 5. The heat transfer tube support structure according to claim 1 is provided in a gas flow path in which a heat transfer tube group for recovering heat from a gas turbine combustion exhaust gas and generating steam is arranged. A characteristic exhaust heat recovery boiler.