JPH02279901A - Waste heat recovery boiler apparatus - Google Patents

Abstract

PURPOSE:To easily displace a saddle, a supporting plate to the deformation of a water drop tube, and to obtain high and low pressure vapor drum supporting device for reducing a bending stress of the downcomer and a stress generated at the root of a vapor drum by providing an arcuately curved surface at least at one of the saddle and the plate. CONSTITUTION:A saddle 48 and a supporting plate 49 are secured with a clip 50 fixed to a supporting beam 47 perpendicularly to the perpendicular direction of a high pressure drum 13. Accordingly, the lower part of a high pressure downcomer tube 25 can be freely rotatably deformed by the curved surface 51a of the saddle 48, and the connector of the saddle 48 to the plate 49 is not irregularly brought into contact even if it is rotatably deformed, and the contact area is always not changed. Accordingly, it can be slid smoothly. Therefore, a bending stress generated at the high pressure downcomer 25 can be reduced, and fatigue strength can be improved even if a waste heat recovery boiler 5 is started or stopped upon DSS operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust heat recovery boiler device such as an exhaust heat recovery boiler, and particularly to a support structure for a steam drum suitable for increasing the support strength of the steam drum.

[Conventional technology] Large-capacity thermal power plants are being constructed to meet the rapidly increasing demand for electricity, but Kowara's thermal power generation boilers operate at variable voltage in order to obtain high power generation efficiency even during partial load. That is required.

This is because, as a feature of recent electricity demand, as nuclear power generation increases, the difference between the maximum and minimum loads has also increased, and boilers for thermal power generation have tended to shift from use for pace-throat use to use for load adjustment.

In other words, when a boiler for thermal power generation is operated for load adjustment, there are few cases in which the boiler load is always operated at full load, and the load is increased and decreased to 75% load, 50% load, and 25% load. or stop driving, etc.
So-called daily start/stop
The power generation system carries out intermediate loads by performing operations such as S top (hereinafter simply referred to as DSS), and operates only during the day when power demand is high, and stops operation at night to improve power generation efficiency.

For example, combined gas turbine plants have recently been attracting attention as a part of high-efficiency power generation. This combined gas turbine plant first generates electricity using a gas turbine, then recovers the exhaust heat in the exhaust gas discharged from the gas turbine using an exhaust heat recovery boiler, and uses the steam generated by the exhaust heat recovery boiler to power the steam turbine. It is operated to generate electricity.

In this way, a combined gas turbine plant has high power generation efficiency because it simultaneously generates power with a gas turbine and a steam turbine, and also has excellent load responsiveness, which is a characteristic of gas turbines. , it can sufficiently cope with descents, has excellent load followability, and is convenient for performing DSSJ rotations.

FIG. 14 is a schematic system diagram of a conventional combined gas turbine plant.

In FIG. 14, combustion air A from an air supply pipe 1 and fuel F from a fuel supply pipe 2 are mixed and combusted in a combustor 3, and the combustion gas is used to rotate a gas turbine 4 to generate electricity by the gas turbine 4. Do the following.

The exhaust gas G that rotates the gas turbine 4 is introduced into the exhaust gas passage 6 of the exhaust heat recovery boiler 5. In this exhaust gas passage 6, from the downstream side to the upstream side, a low pressure boiler 10 consisting of a low pressure economizer 7, a low pressure evaporator 8, and a low pressure steam drum 9, a high pressure economizer 11, a high pressure evaporator 12, a high pressure steam drum 13, and A high pressure boiler 15 consisting of a superheater 14 is arranged.

On the other hand, the feed water WF, which is the fluid to be superheated, is supplied from the water supply pump 16 to the low pressure economizer 7 via the water supply pipe 17, and after being preheated to a predetermined temperature, passes through the low pressure drum water supply pipe 18 to the low pressure steam drum 9. is supplied with water.

The feed water W supplied to the low-pressure steam drum 9 is naturally or forcedly circulated in the order of the low-pressure evaporator 8 and the low-pressure steam drum 9 via the low-pressure downcomer pipe 19 of the low-pressure steam drum 9, during which it is superheated and becomes low-pressure steam. After being separated into water and steam in the tram 9, the water is recycled again to the downcomer pipe 19, the low pressure evaporator 8 and the low pressure steam drum 9, while the steam is transferred to the low pressure main steam pipe 20.
It is supplied to the steam turbine 21 from the steam turbine 21.

On the other hand, a part of the high-temperature water WR diverted at the outlet of the low-pressure economizer 7 is supplied to the high-pressure economizer 11 from the boiler transfer pump 22 via the high-pressure water supply pipe 23, and is preheated to a predetermined temperature. The water is supplied to the high pressure steam drum 13 through the drum water supply pipe 24.

The high-sound water WR supplied to the high-pressure steam drum 13 is circulated through the high-pressure downcomer pipe 25 of the high-pressure steam drum 13 in the order of the high-pressure evaporator 12 and the high-pressure steam drum 13 in the same way as the low-pressure boiler 10. The separated steam is sent to the superheater 14 through the drum steam outlet pipe 26, where it is further heated, and then supplied to the steam turbine 21 through the high-pressure main steam pipe 27, where the steam turbine 21 generates electricity.

Note that the water separated in the high-pressure steam drum 13 is recirculated to the high-pressure downcomer pipe 25, the high-pressure evaporator 12, and the high-pressure steam drum 13.

The level of water supplied to the high-pressure steam drum 13 and the low-pressure steam drum 9 is controlled by operating the high-pressure drum water supply valve 28 and the low-pressure drum water supply valve 29, respectively.

On the other hand, the steam that rotates the steam turbine 21 becomes water in the condenser 3o, and is supplied to the exhaust heat recovery boiler 5 again from the water supply pump 16.

=4 The water supply Wp of this water supply pipe 17 is at a low temperature of approximately 34°C, so if the water is supplied to the low-pressure economizer 7 at the same temperature, low-temperature corrosion will occur in the low-pressure economizer 7, so the low-pressure boiler 1
0. It is necessary to mix the water with high-temperature water WR in the high-pressure boiler 15, raise the temperature of the water supply to a predetermined temperature at which low-temperature corrosion does not occur, and then supply the water to the low-pressure economizer 7.

In other words, a part of the high-temperature water in the high-pressure water supply pipe 23 is supplied from the outlet of the boiler transfer pump 22 to the water supply pipe 17 via the recirculation flow path 33 having the recirculation flow rate adjustment valve 32, and is supplied to the water supply pipe 17 at a low temperature Prevents corrosion.

In addition, 31 is a generator, and 34 is an exhaust gas G of the gas turbine 4.
a denitrification device disposed between the high-pressure evaporator 12 and the high-pressure economizer 1 or between the high-pressure evaporator 12 in order to remove nitrogen oxides (NOx); 35 is a superheated steam communication pipe;
6 is a superheated steam stop valve, and 37 is a pressure regulating valve.

Figures 9 to 13 show the exhaust heat recovery boiler. Figure 9 is a cross-sectional view of the exhaust heat recovery boiler, Figure 10 is a cross-sectional view taken along line X-X in Figure 9, and Figure 11 is a cross-sectional view of the exhaust heat recovery boiler. is a detailed view of the support structure that is an enlarged view of part B in Figure 9, Figure 12 is a side view of Figure 11,
FIG. 13 is a schematic diagram showing deformation of the steam drum, downcomer pipe, and manifold during operation.

In Figures 9 to 13, 5 is an exhaust heat recovery boiler, 6
12 is a high-pressure evaporator, and 13 is a steam drum.

25 is a downcomer which is the same as that shown in FIG.

38 is an evaporator pipe, 39 is a lower evaporator pipe header, 40 is an evaporator upper header, 41 is a water supply pipe, 42 is a rising pipe, 43 is a fireproof wall, 44 is a casing, 45 is a manifold, and 46 is a downcomer pipe support member. , 47 is a support beam, 48 is a saddle, 49 is a support plate, and 50 is a clip.

In such a structure, in the exhaust heat recovery boiler 5 shown in FIGS. 9 and 10, when the exhaust gas G is supplied from the direction of the arrow in FIG.
Steam is generated within the evaporator tube, and this steam is transferred to the upper header 40 of the evaporator tube.
The steam is collected in the high-pressure steam drum 13 through the riser pipe 42 and separated into steam and water.

The water in the high-pressure steam drum 13 then flows into the manifold 45 through which the high-pressure downcomer pipe 25 passes, and from the manifold 45 is led back to the evaporator pipe 38 via a large number of water supply pipes 41 and the evaporator pipe lower header 39.

The weight of the high-pressure steam drum 13 is transmitted to the ground through the high-pressure downcomer pipe 25, via the downcomer support member 46, and supported by the support beam 47. In other words, the high-pressure steam drum 13 has a self-supporting structure supported by the lower part of the high-pressure downcomer pipe 25.

FIGS. 11 and 12 show the conventional support structure for the lower part of the rainwater. The fireproof wall 43 is omitted in FIGS. 11 and 12. A saddle 48, a support plate 49, and a clip 50 are provided as a downcomer support member 46 at the lower part where the high-pressure downcomer pipe 25 and the manifold 45 intersect, and the weight of the high-pressure steam drum 13 is transmitted to the saddle 48 and the support plate 49. is transmitted to the support beam 47, and the saddle 48 is transmitted to the manifold 45.
The support plate 49 and the clip 50 are fixed to the side of the support beam 47.
is fixed.

On the other hand, when the exhaust heat recovery boiler 5 is turned on, the metal temperatures of the high-pressure steam drum 13, high-pressure downcomer pipe 25, and manifold 45 are heated to the internal fluid temperature and become almost equal to the internal fluid temperature. is a fireproof wall 43 (not shown)
Since it is set away from the exhaust gas passage 6, the temperature is equal to the ambient temperature outside the boiler. Therefore, a temperature difference occurs between the exhaust heat recovery boiler 5 and the support beam 47, and a difference in thermal expansion occurs. If this thermal expansion difference is restrained, thermal stress will occur in the high-pressure downcomer pipe 25, leading to a decrease in strength. It has a structure that allows it to slide between the support plate 48 and the support plate 49 to absorb the difference in thermal expansion.

When the exhaust heat recovery boiler 5 is operating, the high-pressure steam drum 13 is
As shown in FIG. 10, the upper part of the high-pressure steam drum 13 is separated into steam and the lower part is water, and a large temperature difference occurs between the steam side and the water side, especially when the exhaust heat recovery boiler 5 is started or stopped. For this reason, the high-pressure steam drum 1 warps like a bimetal, as shown by the broken line in FIG. (13th
(The figure shows a case where the temperature above the high-pressure steam drum 13 is high) In the conventional support structure for the high-pressure steam drum 13, the high-pressure downcomer pipe 25 also deforms, and the saddle 48 of the lower support also generates a rotational deformation angle θ. In other words, since the surfaces of the saddle 48 and the support plate 49 are no longer parallel, uneven contact occurs when the saddle 48 slides, resulting in a locally large load and the slide surface between the lower surface of the saddle 48 and the upper surface of the support plate 49. Galling occurs, making it difficult to slide. If this sliding becomes impossible, the high pressure downcomer pipe 25 and the high pressure steam drum 1
Bending stress is generated at the base of the high-pressure downcomer pipe 25 and the high-pressure steam drum 1, and the bending stress is repeated every time the exhaust heat recovery boiler 5 is started and stopped, resulting in a decrease in fatigue strength.
3 will be destroyed.

[Problems to be Solved by the Invention] In the support structure of the prior art, the high-pressure steam drum 13 is supported at the lower part of the high-pressure downcomer pipe 25, and thermal expansion due to the temperature difference between the high-pressure steam drum 13 or manifold 45 and the support beam 47 occurs. When the difference is absorbed by the slide, the high pressure steam drum 13
No consideration was given to rotational deformation of the lower part of the high-pressure downcomer pipe 25 due to deformation of the high-pressure downcomer pipe 25, resulting in a reduction in the strength of the high-pressure downcomer pipe 25 and the high-pressure steam drum 13.

The present invention attempts to eliminate such drawbacks of the prior art, and its purpose is to closely follow the rotational deformation at the bottom of the downcomer pipe and to smoothly slide due to thermal expansion of the steam drum. Another object of the present invention is to provide a support device for a high-pressure steam drum or a low-pressure steam drum that can reduce the bending stress of downcomer pipes and the stress generated at the base of the steam drum.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides at least one of the saddle and the support plate with an arcuate curved surface.

[By providing an arc-shaped curved surface on at least one of the working saddle and the support plate, the saddle and the support plate can be easily rotated and displaced in response to deformation of the downcomer pipe due to deformation of the steam drum. - Since there is no uneven contact between the slide portion of the rail and the support plate, thermal expansion due to temperature differences can be absorbed.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 8 relate to embodiments of the present invention, and FIGS.
Figures 3, 5 and 7 are front views, and Figures 2, 4, 6 and 8 are side views of Figures 1, 3, 5 and 7. It is a diagram.

In Figures 1 to 8, 25 is a high-pressure downcomer, 45 is a manifold, 46 is a support member, 47 is a support beam, 48 is a saddle, 49 is a support plate, and 50 is a clip, which is the same as the conventional one. show.

51a, 51b, and 51c are arcuate curved surfaces provided on the sliding surfaces of the saddle 48 and the support plate 49.

In such a structure, as shown in FIGS. 1 and 2, a saddle 48 is fixed to the high-pressure downcomer pipe 25 side,
A support plate 49 and a clip 50 are fixed to the support beam 47 side. The saddle 48 and the support plate 49 are structured to slide in the axial direction of the high-pressure tram 13 (in the left-right direction with respect to the paper surface of FIG. 1), and the lower surface of the saddle 48 has an arc-shaped curved surface 51a. is provided.

The saddle 48 and the support plate 49 are attached to the support beam 4 in the direction perpendicular to the axis of the high-pressure drum 13 (in the left-right direction with respect to the paper surface of FIG. 2).
It is fixed with a clip 50 fixed to 7. Therefore, as shown in FIG. 13, even when the high-pressure steam drum 13 is deformed, the lower part of the high-pressure downcomer pipe 25 remains on the curved surface 51 of the saddle 48.
It can be freely rotated and deformed by a, and
The connection between the saddle 48 and the support plate 49 does not come into contact even when rotated and deformed, and the contact area always remains the same, so they can slide smoothly. Therefore, the bending stress generated in the high-pressure downcomer pipe 25 can be reduced, and the DS of the exhaust heat recovery boiler 5 can be reduced.
Fatigue strength can be improved even when starting and stopping accompanying S operation are performed.

3 and 4 show other embodiments,
The difference from the one in FIGS. 1 and 2 is that in the one in FIGS. 1 and 2, an arc-shaped curved surface 51a is provided on the lower surface of the saddle 48, but in the one in FIGS. The lower surface of the saddle 48 is flat, and only the upper surface of the support plate 49 is provided with an arcuate curved surface 51b.

That is, as shown in FIGS. 3 and 4, the bottom surface of the saddle 48 attached to the lower part of the high-pressure downcomer pipe 25 is flat, but the curved surface 51 is formed only on the upper surface on the side of the support plate 49 that becomes the sliding part.
b.

The arc-shaped curved surface 51b provided on the upper surface of the support plate 49 provides substantially the same effect as that in FIGS. 1 and 2.

5 and 6 show other embodiments,
The difference from the one in FIGS. 1 to 4 is that the one in FIGS. 1 and 2 has an arcuate curved surface 51a only on the saddle 48, and the one in FIGS. 3 and 4 has a support plate. 5 and 6, both the saddle 48 and the support plate 49 are provided with arcuate curved surfaces 51a and 51b.

In other words, as shown in FIGS. 5 and 6, the high pressure downcomer 2
The sliding surface of the saddle 48 attached to the 5th side has an arc-shaped curved surface 51a, and the sliding surface of the supporting plate 49 side corresponding to this curved surface 51a also has an arc-shaped curved surface 51b in the same direction as the curved surface 51a of the saddle 48. It has been established. Like this,
Arc-shaped curved surfaces 51a are provided on both contact surfaces between the saddle 48 and the support plate 49.

51b ensures a large contact area on the sliding surface, which is especially effective when the supporting load is large, and it is possible to reduce the surface pressure on the sliding surface, allowing smooth rotational deformation and sliding movement, making it possible to improve the quality of high-pressure downcomers. 25 bending stress can be reduced, and the fatigue strength associated with starting and stopping during DSS operation can be increased.

7 and 8 show other embodiments.
The one shown in FIG. 8 and FIG.
1e and has a rotating structure. In this way, the difference in expansion between the high-pressure drum 13 or the high-pressure downcomer pipe 25 and the support beam 47 can be absorbed by the rotation of the support plate 49.

In other words, the high-pressure downcomer pipe 25 is supported by rollers, and at the same time,
Since the rotational displacement of the high-pressure downcomer pipe 25 can be smoothly tolerated, there is no need to slide it on the bottom surface of the saddle 48, and the frictional force at the time of sliding is reduced, thereby reducing the bending stress acting on the high-pressure downcomer pipe 25. I can do it.

As described above, in the embodiment of the present invention, the high pressure steam drum 13
Although the present invention has been explained using the support structure of the present invention as an example, the present invention is not limited to the actual flow side, and can also be applied to the support structure of the low-pressure steam drum 9.

[Effects of the Invention] According to the present invention, the rotational variation of the downcomer support part due to the vertical deformation of the steam drum can be freely deformed without being restrained, and it can be smoothly deformed even against the difference in thermal expansion with the support beam. can be slid into.

[Brief explanation of drawings]

FIGS. 1 to 8 relate to embodiments of the present invention, and FIGS.
Figures 3, 5, and 7 are front views, Figures 2, 4, 6, and 8 are Figures 1, 3, 5,
Figure 7 is a side view, Figure 9 is a cross-sectional view of the exhaust heat recovery boiler,
Fig. 10 is a sectional view taken along the line X-X in Fig. 9, Fig. 11 is a detailed view of the conventional support structure, which is an enlarged view of part B in Fig. 9, and Fig. 12 is a detailed view of the support structure shown in Fig. 11. A side view, FIG. 13 is a schematic diagram showing deformation of the steam drum, downcomer pipe, and manifold during operation, and FIG. 14 is a schematic system diagram of the gas turbine combined cycle plant. 5...Exhaust heat recovery boiler, 9...Low pressure steam drum, 13...High pressure steam drum, 19...
・Low pressure downcomer pipe, 25...High pressure downcomer pipe, 45...
...Manifold, 47...Support beam, 48...
... Saddle, 49 ... Support plate, 51 a, 5
l b , 51 c --Curved surface. V\r

Claims (1)

[Claims] a steam drum; a downcomer supporting both ends of the steam drum;
An exhaust heat recovery boiler is formed by a manifold that connects downcomer pipes, and a saddle is provided at both ends of the manifold side, and a support plate is provided on the support beam side, and the sliding between the saddle and the support plate recovers the exhaust heat. An exhaust heat recovery boiler device for absorbing elongation of a recovery boiler, characterized in that at least one of the saddle and the support plate is provided with an arcuate curved surface.