JPH046396A - Heating device recovering waste heat - Google Patents

Abstract

PURPOSE:To shorten the length of a boiler and eliminate the generation of thermal stress restricting the mutual thermal expansion difference between heat transfer tubes by a method wherein the title heating device is provided with hanging fittings, hung down from the upper part of a flue, and tunular support members, supported by the fittings and provided with arced parts at the upper parts thereof, to support the upper bent parts of reversed U-shape heat transfer tubes by the support members. CONSTITUTION:A heat transfer tube 21a, positioned at the substantially center of a secondary superheater inlet header 20 and a secondary superheater outlet header 22 and connected so as to have a gate type, is bent about a support pipe 26 arranged above heat transfer tubes at a front flow side and the rear flow side of gas to use it as a hung-down tube, the own weight of the heat transfer tube 21a is supported by a support pipe 26, a hanging fitting 27 for supporting the load is attached to the support pipe 26 and the title heating device is supported by hanging it down from the upper part of the flue 24a of a boiler. The other heat transfer tubes 21b, arranged in zigzag so as to make a pair with the heat transfer tube 21a, are arranged so as to pass under the support pipe 26 and are supported by a shear lug 28 attached to the heat transfer tube 21a at a place whereat the heat transfer tube 21b is intersected with the other heat transfer tube 21b.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an exhaust heat recovery heating device, and particularly to a heat exchanger tube provided in the device that allows the heat transfer tubes to freely expand and contract to suppress the generation of thermal stress. The present invention relates to an exhaust heat recovery heating device having a heat transfer tube support structure suitable for.

[Conventional technology]

Recently, combined cycle power plants have been attracting attention as a part of high-efficiency power generation. This combined power generation plant first generates electricity using a gas turbine, and then recovers the heat in the exhaust gas discharged from the gas turbine in an exhaust heat recovery boiler.
The steam generated by this exhaust heat recovery boiler operates a steam turbine to generate electricity.

This combined power generation plant uses a gas turbine and a steam turbine to generate electricity, so in addition to achieving high power generation efficiency, the gas turbine has high load responsiveness and is able to adequately respond to sudden increases in power demand. There are also benefits to be gained.

The present invention relates to such an exhaust heat recovery boiler, and particularly to an exhaust heat recovery boiler in which a heat transfer tube is disposed inside a flue through which exhaust gas flows horizontally. The conventional technology is shown in Figures 13 and 14.
This will be explained using figures.

In the exhaust heat recovery boiler, primary and secondary superheater pipes 16, 21, evaporator pipes 11, A economizer tube 3 is arranged. Feed water led from a water supply pump (not shown) enters the economizer inlet header 2 through the water supply pipe 1, ascends the economizer pipe 3, and is collected at the economizer outlet header 4. The gas enters the economizer inlet header 2 on the upstream side of the gas via the connecting pipe 5. This flow is repeated one after another, and the feed water exiting the economizer outlet header 4 in the front row of gases passes through the drum water supply pipe 6 and enters the steam drum 7. The feed water in the steam drum 7 passes through the downcomer pipe 8 and the water supply pipe 9, enters the evaporator inlet header 11, passes through the evaporator outlet header 12 and the riser pipe 13, and returns to the steam drum 7. come back to.

On the other hand, the steam separated from steam and water in the steam drum 7 passes through the superheater inlet connecting pipe 14 and enters the primary superheater header 15.
passing through the primary superheater pipe 16 and the primary superheater outlet header 17;
The superheated steam is guided to the secondary superheater inlet header 20 via the attemperator 19 for controlling the temperature of the superheated steam, and is superheated to a predetermined temperature in the process of rising and falling in the secondary superheater pipe 21.
The steam is collected in the secondary superheater outlet header 22, and the main steam pipe 23
from there to a steam turbine (not shown).

Economizer tube 3 and evaporator tube 11.1 for heat exchange with exhaust gas
Next, the heat transfer tube group of the secondary superheater tubes 16 and 21 uses finned tubes with excellent heat recovery and a good space factor, and is arranged in a staggered arrangement. In addition, in order to quickly respond to daily startup and shutdown of the heat exchanger tube group, a pipe header 2.10.17.20.22 is installed at the bottom to drain the condensate that accumulates inside the heat exchanger tube group during shutdown. It has become.

As shown in FIG. 14, in such a heat exchanger tube, the lower header 20.
4b. Therefore, the heat exchanger tube thermally expands upward starting from the lower header 20.22. Therefore, the secondary superheater tube 21 has four
Although a row of heat exchanger tubes are provided, the steam temperature inside the heat exchanger tubes differs due to heat exchange with the exhaust gas G on the gas upstream side and the downstream side of the heat exchanger tubes. In other words, the steam temperature on the upstream side of the exhaust gas is high, and therefore the metal temperature of the heat exchanger tube on the upstream side is higher.

For this reason, thermal stress that restricts the difference in thermal expansion is generated in the heat exchanger tubes on the upstream and downstream sides of the exhaust gas, so the upper horizontal part is made longer and the horizontal part absorbs the difference in thermal expansion. It has flexibility. As a result, a space is required between the heat exchanger tubes on the gas upstream side and the downstream side, resulting in an increase in the length of the entire boiler device, which has the drawback of increasing the length of the flue, leading to an increase in cost. Furthermore, no matter how many horizontal sections are provided to provide flexibility, this will not eliminate the stress caused by the difference in thermal expansion, and especially if the plant starts and stops frequently every day, such as in a combined cycle power plant, fatigue may result. It had the disadvantage of being destroyed.

Further, as another example of the prior art, as shown in FIG. 14, there is a case in which a hend is provided on the upper part to provide flexibility. Similarly, in this case, it is necessary to secure enough space to avoid interference with adjacent heat exchanger tubes.
In addition to the disadvantage of having a long flue, there was also the problem of fatigue failure due to thermal stress, similar to the above.

(Problems to be Solved by the Invention) The above conventional technology requires a space for installing horizontal heat exchanger tubes in order to absorb the difference in thermal expansion between the heat exchanger tubes in the structure that supports the heat exchanger tubes. This has the disadvantage of increasing the length of the flue that encloses the heat transfer tube, resulting in an increase in cost.Also, no matter how flexible it is, thermal stress itself restricts the difference in thermal expansion. Since the occurrence of this cannot be eliminated, there is a problem in that fatigue failure occurs due to daily startup and shutdown.

An object of the present invention is to provide an exhaust heat recovery heating device that reduces the length of a boiler and does not generate thermal stress that restricts the difference in thermal expansion between heat exchanger tubes.

[Means for Solving the Problems] The object of the present invention described above is to provide an inlet header into which a fluid to be heated enters, an outlet header through which heated fluid to be heated exits, and an inlet header and an outlet. Inverted U for connecting headers
In an exhaust heat recovery heating device installed in a flue gas flue installed in a nearly horizontal direction, a heater consisting of a plurality of heat transfer tubes that rise in a letter-shaped manner and then curve downwards is suspended from the upper part of the flue. It is characterized by having a lowered hanging fixture and a cylindrical support member supported by the hanger and having an arcuate portion at the upper part, so that the upper curved part of the inverted U-shaped heat exchanger tube is supported by the support member. an inlet header where the heated fluid enters, an outlet header where the heated fluid exits, and an inverse header for connecting the inlet header and outlet header. In an exhaust heat recovery heating device, a heater consisting of multiple heat transfer tubes that rise in a U-shape and then curve downwards is installed in a flue gas flue installed in a nearly horizontal direction, from the top of the flue. It has a suspended hanging fixture and a cylindrical support member supported by the hanging fixture and having an arcuate portion at the upper part, and a part of the inverted U-shaped heat exchanger tube has its curved part supported by the cylindrical support member, The remaining heat exchanger tubes are supported by a shear lug provided on the supported heat exchanger tubes. This is achieved by the exhaust heat recovery heating device.

[Effect]

By supporting the heat exchanger tube with an arc-shaped support member installed at the upper part between the gas upstream and downstream sections, the thermal expansion of the heat exchanger tube will start from the support pipe and extend downward. Since the thermal expansion of the heat exchanger tubes can be performed freely, the difference in thermal expansion between the heat exchanger tubes is not restricted. Therefore, there is no need for a horizontal portion that makes the heat exchanger tubes flexible, so the length of the entire boiler can be shortened, and thermal stress due to differences in thermal expansion is no longer generated.

〔Example〕

A specific embodiment according to the present invention is shown in FIGS. 1 and 2. This figure shows the secondary superheater tube 21 of the prior art shown in FIG. 13. FIG. 2 shows an AA view of FIG. 1. In addition, Fig. 3 shows an enlarged view of part A in Fig. 1,
FIG. 4 shows an AA view of FIG. 3. As shown in FIG. 1, the heat transfer tubes 21a connected in a gate shape located approximately at the center of the secondary superheater inlet header 20 and the secondary superheater outlet header 22 are connected to the gas upstream side and the downstream side. The heat exchanger tubes 21a are bent along support pipes 26 disposed in the upper part between the heat exchanger tubes to form a hanging tube, and the dead weight of the heat exchanger tubes 21a is deposited on the support pipes 26.
A hanging fitting 27 for supporting a load is attached to the support pipe 26, and the support pipe 26 is suspended and supported from the upper part of the boiler flue 24a via the hanging fitting 27. The other heat exchanger tube 21b, which is arranged in a staggered manner as a pair with the heat exchanger tube 21a, is arranged so as to pass under the support pipe 26, and is attached to the heat exchanger tube 21a at a place where it intersects with the heat exchanger tube 21a. It is supported by Shahrag on the 2nd.

With such a structure, the heat exchanger tubes 21a and 21b on the gas upstream side and the downstream side are supported by hanging from the upper support pipe 26, so that they can freely expand thermally downward. Therefore, the difference in thermal expansion between the heat exchanger tubes on the gas upstream side and the downstream side is not constrained, and there is no need to provide a horizontal heat exchanger tube section to absorb the difference in thermal expansion as in the prior art. Therefore, there is no need to secure a space for this, and there is an effect that the length of the boiler can be shortened. In addition, the innermost heat transfer tube 21a
becomes a hanging tube, and other heat exchanger tube group 21b is attached to this hanging tube.
Since the headers 20 and 22 are supported, the space between the headers 20 and 22 can be narrowed, and the length in the flow direction of the exhaust gas G can be shortened accordingly, resulting in a smaller size.

In addition, DSS operation (Daify 5tartsto
Since thermal expansion is allowed to occur freely even when the P-operation is performed, thermal stress due to the difference in thermal expansion is not generated, and the problem of fatigue failure is resolved.

Furthermore, although this embodiment shows an example in which the support pipe 26 is made of a hollow material, the same effect can be obtained even if the support pipe 26 is made of a semi-cylindrical material having a solid body or an arcuate upper surface. Furthermore, although the secondary superheater tube 21 has been described in this embodiment, the same effect can be obtained even if the present invention is employed in a primary superheater or other heat exchanger tubes.

Note that in the above embodiment, the heat exchanger tube 21a is supported by a support pipe supported by a hanging fitting 27, and the heat exchanger tube 21b is supported by a shear lug 28 provided on the heat exchanger tube 21a, but the heat exchanger tubes 21a and 21b are Alternatively, the present invention also includes supporting each with the same or separate support pipes supported by separate support fittings.

Other embodiments of the invention are shown in FIGS. 5-8. Figure 6 is the 5th
AA homeland in the figure, FIG. 7 is an enlarged view of part A in FIG. 5, and FIG. 8 shows AA homeland in FIG.

The heat exchanger tubes 21a on both sides of the support pipe 26
It is installed on. With this structure, the shear lug 28
The load acting on one piece can be distributed. Therefore, the wall thickness of the heat exchanger tube 21a for supporting the load can be reduced.

9 to 12 show another embodiment of the present invention, in which a set of three heat exchanger tubes is used. Figure 10 is A- in Figure 9.
A indicates the homeland. Figure 11 is an enlarged view of part A in Figure 9.
Figure 2 shows the A-A homeland in Figure 13. In this example, the fifth
In addition to the other embodiments shown in the drawings, the outermost heat exchanger tube 21c is supported by being placed on the center heat exchanger tube 21b via a spacer 29. The present invention also has the same effect as the other embodiment (FIG. 5).

[Effects of the Invention] According to the present invention, even when DSS operation is performed, the heat exchanger tubes can freely expand thermally, so the difference in thermal expansion between the heat exchanger tubes is not restricted, so there is no need to provide the heat exchanger tubes with special flexibility. This has the effect that the overall length of the boiler can be shortened, and thermal stress due to differential thermal expansion does not occur.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the first embodiment of the present invention, Fig. 2 is the A-A homeland in Fig. 1, Fig. 3 is an enlarged view of section A in Fig. 1, and Fig. 4 is the Figure AA homeland, Figure 5 2, the second embodiment of the present invention, Figure 6 is an AA view of Figure 5, Figure 7 is an enlarged view of part A of Figure 5, 8 shows the A-A homeland in FIG. 7, FIG. 9 shows the third embodiment of the present invention, FIG. 10 shows the A-A homeland in FIG. 9, and FIG. Enlarged view of part A in the figure, 1st
Figure 2 shows the A-A homeland in Figure 1I, Figure 13 shows the heat pipe installation explanatory diagram of a conventional exhaust heat recovery boiler, and Figure 14 shows the secondary superheating of a conventional exhaust heat recovery boiler. It is an explanatory diagram of the installation of the pipes.■... Water supply pipe, 2... Economizer header, 3... Economizer pipe, 4... Economizer outlet header, 5... Economizer connection pipe, 6...Drum water supply pipe, 7...Steam drum, 8.
... Downpipe, 9... Water supply pipe, 10... Evaporator inlet header, 11... Evaporator outlet pipe, 12... Evaporator outlet header, 13... Rising pipe, 14...・Superheater inlet connection pipe,
15... Primary superheater inlet header, 16... Primary superheater pipe, 17... Primary superheater outlet header, 18... Superheater connection pipe, 19... Desuperheater , 20... Secondary superheater inlet header, 21... Secondary superheater pipe, 22... Secondary superheater outlet header, 23... Main stem trachea, 24'' Flue, 24a ... Flue top wall, 24b... Flue bottom wall, 2
5...Support metal fittings, 26...Support pipe, 2
7... Hanging fittings, 28... Sharing lugs, 29... Spacers. Applicant Habcock Hitachi Co., Ltd. Agent Patent Attorney Takeshi Kawakita Steam Drum Downcomer Flood Pipe Evaporator Inlet Header Evaporator Tube Evaporator Outlet Header Rising Pipe Superheater Inlet Connecting Pipe Primary Superheater Inlet Header Primary Superheater Tube Primary Superheater Outlet Header Superheater Connecting Pipe Desuperheater 2 Next superheater inlet header Secondary superheater tube Secondary superheater outlet header main steam pipe Flue top wall Flue bottom wall

Claims (2)

[Claims] (1) An inlet header where the heated fluid enters, an outlet header where the heated fluid exits, and an inverted U-shaped rise to connect the inlet header and outlet header. A hanging fixture suspended from the top of the flue in an exhaust heat recovery heating device in which a heater consisting of a plurality of curved and descending heat transfer tubes is installed in a combustion exhaust gas flue installed in an almost horizontal direction. and a cylindrical support member supported by the support member and having a circular arc portion at the upper part, and the upper curved part of the inverted U-shaped heat exchanger tube is supported by the support member. Device. (2) An inlet header where the heated fluid enters, an outlet header where the heated fluid exits, and an inverted U-shaped raised header to connect the above-mentioned inlet header and outlet header. In an exhaust heat recovery heating device, a heater consisting of multiple heat transfer tubes that curve downward and is installed in a flue gas flue installed in a nearly horizontal direction, a heater suspended from the top of the flue is used. It has a metal fitting and a cylindrical support member supported by the metal fitting and having an arcuate portion at the upper part, and a part of the inverted U-shaped heat exchanger tube has its curved part supported by the cylindrical support member, and the remaining heat exchanger tube An exhaust heat recovery heating device characterized in that the supported heat transfer tube is supported by a shear lug provided on the supported heat transfer tube.