JP5693311B2 - Heat transfer tube structure - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a heat transfer tube structure of a boiler furnace, and more particularly to a connection structure of a horizontally placed heat transfer tube and a suspended heat transfer tube having different numbers of tubes, and a heat transfer tube structure capable of reducing the members constituting them.

  FIG. 5 is a side view schematically showing the arrangement of the heat transfer tubes inside the boiler furnace. The plate-type heat transfer tube group 13 or the U-type heat transfer tube group 14 exposed to the high-temperature combustion gas is arranged at a relatively large distance from, for example, 1600 mm and 800 mm, respectively, with the adjacent tube groups in the vertical direction of the paper. Yes. This is closely related to the melting point and softening point of coal ash, and the molten ash adheres to the tube group and repeats the phenomenon of growth. This is to prevent blocking.

  On the other hand, the portions where the suspension inlet heat transfer tubes 3 and the suspension outlet heat transfer tubes 4 on the downstream side of these suspension heat transfer tube groups 13 and 14 are disposed are the exhaust gas heat-exchanged by the heat transfer tube groups 13 and 14. Since it is on the downstream side of the flow, it is a region where the ambient temperature is lower than the portion where the heat transfer tube groups 13 and 14 are disposed. For this reason, when coal having a high ash melting point is used, even if the interval between the hanging inlet heat transfer tube 3 and the hanging outlet heat transfer tube 4 and the adjacent tube group in the vertical direction on the paper surface is reduced to about 200 mm, the transfer of these tubes is reduced. As the ash adhering to the heat tubes 3 and 4 melts, there is no problem that the heat transfer tubes 3 and 4 are connected to adjacent tube groups and the gas flow path is blocked.

  However, in recent years, with the diversification of coal types, coal with a low ash melting point has begun to be used. In such a case, from the viewpoint of preventing the connection of ash as described above, the suspension is configured in a panel shape. It is necessary to increase the distance between the inlet heat transfer tube 3 and the adjacent tube group of the suspended outlet heat transfer tube 4 to, for example, about 450 mm. However, when the interval between the adjacent tube groups is about 450 mm, the total number of the suspended inlet heat transfer tubes 3 arranged in a certain space is reduced compared to the structure arranged at the interval of 200 mm. Inevitably, there will be a large difference in the total number of tubes between the hanging inlet heat transfer tubes 3 and the horizontally placed heat transfer tubes 2 arranged on the downstream side of the hanging outlet heat transfer tubes 4.

  FIG. 7 shows a horizontal heat transfer tube 2 arranged in a non-known boiler furnace, which is considered as a countermeasure when there is a large difference between the total number of hanging inlet heat transfer tubes 3 and the total number of horizontal heat transfer tubes 2. It is a perspective view of the part which shows the connection structure of the hanging inlet heat exchanger tube 3 and the outlet heat exchanger tube 4, and FIG. 8 is the fragmentary side view seen from the HH line | wire of FIG.

  In the structure shown in FIGS. 7 and 8, the horizontal heat transfer tubes 2 pass through the ceiling wall tube 12, and then a plurality of horizontal heat transfer tube outlets installed at the upper end of the boiler furnace width direction (the direction perpendicular to the plane of FIG. 5). Connected to the header 7 (in FIG. 7, not only the header 7 but also the headers 5 and 10 are only partly shown at both ends), the horizontal heat transfer tube outlet header 7 is connected to the lateral header. The fluid flowing in the horizontal heat transfer tube 2 was gathered by being connected to the heat tube outlet manifold 8. In order to further heat the fluid, the horizontal heat transfer tube outlet header 7 is connected to the suspended heat transfer tube 3 by connecting piping 9A, 9B.

 The fluid flowing out from the connecting pipes 9A and 9B is distributed to each suspended heat transfer pipe inlet header 10 via the suspended heat transfer pipe inlet manifold 11, and from each suspended heat transfer pipe inlet header 10 to the suspended inlet heat transfer pipe 3. And after being sent to the suspension outlet heat transfer tube 4 and overheated, it passes through the suspension heat transfer tube outlet header 5 and is sent to the turbine via the suspension heat transfer tube outlet manifold 6.

  When the total number of the horizontal heat transfer tubes 2 in the boiler furnace width direction and the total number of the suspension inlet heat transfer tubes 3 are different as shown in FIGS. 7 and 8, the horizontal heat transfer tubes 2 and the suspended heat transfer tubes 2 are suspended. Since the heat transfer tubes cannot be directly connected to each other, the heat transfer tubes 3 cannot be directly connected to each other. Therefore, the individual horizontal heat transfer tube outlet header 7 and the outlet manifold 8, and the suspended heat transfer tube inlet manifold 11 and the suspended heat transfer tube inlet header 10. It can be considered that a configuration is used in which the connecting pipes 9A and 9B are connected.

  The manifolds 6, 8, and 11 to which the headers 5, 7, and 10 are respectively connected can also be used as headers in order to achieve the purpose. FIG. 9 shows an example of the configuration, and FIG. 9 is a partial side view of a portion J surrounded by a broken line in FIG. As described above, the internal fluid in the horizontal heat transfer tube 2 is collected to the horizontal heat transfer tube outlet manifold 8 via the horizontal heat transfer tube outlet header 7. As shown in FIG. 9, even if the horizontal heat transfer tube 2 is directly connected to the horizontal heat transfer tube outlet manifold 8 without using the horizontal heat transfer tube outlet header 7, the internal fluid can be collected in the manifold 8. Similarly, the heat transfer tubes 3 and 4 can be directly connected to the manifolds 8 and 11.

  However, in this configuration example, considering the ease of product transportation to the boiler construction site and the ease of product loading / unloading at the construction site, the horizontal heat transfer pipe 2 and the horizontal heat transfer pipe outlet manifold 8 are welded and joined at the product manufacturing factory. It is not realistic to carry it into the boiler construction site in such a state because it is 10 m or more in the height direction and 20 m or more in the length direction.

  Therefore, it is necessary to divide the horizontal heat transfer tube outlet manifold 8 to which the horizontal heat transfer tube 2 is welded and the horizontal heat transfer tube 2 into the construction site at the position D in FIG. At the boiler construction site, the boiler is assembled by heat transfer tube welding at part D, and the number of welders (number of points) increases by several tens to several hundreds times at the narrow part. The outlet header 7 is arranged individually, the horizontal heat transfer pipe 2 and the horizontal heat transfer pipe outlet header 7 are factory-welded, and the horizontal heat transfer pipe outlet header 7 and the horizontal heat transfer pipe outlet manifold 8 are locally installed. It is conceivable to use a procedure for assembling a welded boiler.

Japanese Patent Laid-Open No. 9-60810

  The above-described heat transfer tube structure shown in FIGS. 7, 8 and 9 has manifolds 6 and 8 for collecting the fluid in the header in order to carry the fluid collected in the headers 5, 7, and 10 to the downstream side. 11 and connecting pipes 9A and 9B for connecting the flow paths. Therefore, there are many components to configure, and the configuration is costly. In addition, the amount of welding work during installation of these parts on-site tended to be large.

  In Patent Document 1, an intermediate panel and a side panel are provided between a plurality of entrance pipes and an outlet pipe, and a laterally extending portion is formed on the side panel so that a predetermined interval is provided between the panels. In addition, it is described that the structure of the entire header can be simplified by holding and connecting the inlet communication pipe and the outlet communication officer to the upper side of each of the lengthwise intermediate portions of the inlet and outlet headers.

  However, the invention described in Patent Document 1 does not relate to the heat transfer tube structure in the case where the total number of the suspended heat transfer tubes and the horizontally placed heat transfer tubes is the subject of the present invention. In the boiler furnace used, there was no difference in the total number of the suspended heat transfer tubes and the horizontal heat transfer tubes, or in the interval between the heat transfer tubes in the boiler furnace width direction.

  Therefore, an object of the present invention is to prevent the ash from being accumulated between the panels when the heat transfer tubes such as the suspended heat transfer tubes and the horizontal heat transfer tubes are arranged in a panel shape, and to connect the panels. The object is to provide a heat transfer tube structure that can be easily transported and installed in the field (final assembly) without using a manifold or connecting pipe.

  The heat transfer tube structure according to the present invention is intended to solve the above-described problems, and has a structure in which the weight of constituent members can be reduced without being affected by the number of horizontal heat transfer tubes and suspended heat transfer tubes. Furthermore, it is set as the structure which improves installation property by reducing a number of parts.

 The invention described in claim 1 is a suspended heat transfer tube 3 in which a plurality of heat transfer tubes are suspended in the front-rear direction of the boiler, and a plurality of heat transfer layers that are horizontally placed in the front-rear direction of the rear heat transfer portion of the boiler and stacked vertically. The heat tubes are sequentially folded and stacked from the lower side to the upper side of the rear heat transfer unit, the horizontal heat transfer tube 2 having a vertical portion extending in the vertical direction is provided above the rear heat transfer unit, and the boiler ceiling wall 12 is penetrated to pass through the heat transfer tube 2. A vertical portion of the suspended heat transfer tube 3 and the horizontal heat transfer tube 2 is extended, and the vertical portion of the suspended heat transfer tube 3 and the horizontal heat transfer tube 2 are connected by an intermediate header 1 above the boiler ceiling wall. The heat transfer tube structure is characterized in that a plurality of heat exchange units are arranged in the boiler furnace width direction.

 According to the second aspect of the present invention, the suspended heat transfer tubes 3 of the set of heat exchange units are configured such that the heat transfer tubes connected to the intermediate header 1 are respectively bent below the ceiling wall 12 toward the boiler rear side. And is connected to the outlet header 5 of the suspended heat transfer tube 4 above the intermediate header 1 so as to pass through the ceiling wall 12 and straddle the intermediate header 1. 1. The heat transfer tube structure according to 1.

 According to a third aspect of the present invention, in the suspended heat transfer tube 3 of the set of heat exchange units, the heat transfer tubes connected to the intermediate header 1 are respectively bent below the ceiling wall 12 toward the front side of the boiler. And is connected to the outlet header 5 of the suspended outlet heat transfer tube 4 above the intermediate header 1 so as to pass through the ceiling wall 12 and straddle the intermediate header 1. Item 2. The heat transfer tube structure according to Item 1.

  According to the first aspect of the present invention, even if the horizontal heat transfer tubes 2 and the suspended heat transfer tubes 3 having different total numbers of heat transfer tubes are used, the individual heat transfer tubes 2 and 3 are connected to each other independently. By integrating the inlet and outlet headers of the heat transfer tubes 2 and 3 without using a header, ash does not accumulate between the panels when the heat transfer tubes are arranged in a panel, and the boiler pressure resistance The number of parts can be reduced and the weight can be reduced. In addition, reducing the number of parts has a great effect on transportation and installation.

  According to the second aspect of the present invention, since the intermediate header 1 does not pass through the interval between the adjacent tubes of the suspended outlet heat transfer tube 4, a relatively short intermediate header can be used and transportability is improved. Will improve.

  According to invention of Claim 3, since the hanging outlet heat exchanger tube 4 is arrange | positioned at the low temperature side of the gas flow in a furnace, the wall thickness of the hanging outlet heat exchanger tube 4 can be made comparatively thin.

It is a side view which shows the heat exchanger tube arrangement | positioning structure of Example 1 of this invention. It is a BB line arrow top view of FIG. It is AA arrow sectional drawing of FIG. It is a side view which shows the heat exchanger tube arrangement structure of Example 2 of this invention. It is a side view which shows the arrangement configuration of the heat exchanger tube of the whole boiler. It is explanatory drawing regarding the difference of the generated stress of the structure which connects this invention and the structure of a prior art, and a heat exchanger tube group. It is a perspective view which shows the conventional structure which connects the heat exchanger tube group from which a total number of tubes differs. It is a partial side view which shows the conventional structure which connects the heat exchanger tube group from which a total number of tubes differs. It is a partial side view which shows another method of the conventional structure which connects the heat exchanger tube group from which a total number of tubes differs.

  Embodiments of a heat transfer tube structure for a boiler according to the present invention will be described below with reference to the drawings. In addition, the heat exchanger tube of a present Example is concerned with the heat exchanger tube arrange | positioned in the boiler shown in FIG.

In FIG. 1, the horizontal heat transfer tubes 2 and the suspended inlet heat transfer tubes 3 do not match the total number of tubes. As an example, assume the following.
That is, the horizontal heat transfer tube 2 is composed of 14 tubes per panel, 104 panels per steam generator, and there are a total of 1456 tubes. On the other hand, the suspension inlet heat transfer tube 3 and the suspension outlet heat transfer tube 4 are composed of 20 panels for one panel and 52 panels for a total of 1040 tubes. Since the number of heat transfer tubes of the horizontal heat transfer tube 2 and the suspension inlet heat transfer tube 3 are different, the horizontal heat transfer tube 2 and the suspension inlet heat transfer tube 3 cannot be directly connected. Therefore, these tube groups are connected to the intermediate header 1.

  In other words, in one intermediate header 1, a suspended heat transfer tube 2 panel having different intervals in the furnace width direction, and a suspension inlet heat transfer tube 3 and a suspension outlet heat transfer tube 4 panel are suspended. Connect the heat transfer tube panel.

  In the case of this example, since the number of panels of the horizontal heat transfer tube 2 and the suspension inlet heat transfer tube 3 shown in FIG. 2 has a two-to-one relationship, the horizontal heat transfer tube 2 has four panels connected to the suspension inlet. If the two heat transfer tubes 3 are connected to one intermediate header 1, all the heat transfer tubes can be connected to the intermediate header 1 equally. Through this intermediate header 1, the internal fluid passes from the suspension inlet heat transfer tube 3 through the suspension outlet heat transfer tube 4, enters the suspension heat transfer tube outlet header 5 shown in FIG. 1, and enters the suspended heat transfer tube outlet manifold 6. Mixed in. According to the present embodiment, a total of 26 intermediate headers 1 are arranged.

The arrangement of the suspended outlet heat transfer tube 4 and the intermediate header 1 will be described with reference to FIG.
In order to prevent an excessive increase in the temperature of the heat transfer tube, the lower-temperature hanging inlet heat transfer tube 3 is disposed on the upstream side (gas high temperature side) of the in-furnace gas. Therefore, the intermediate header 1 must be arranged so as to reach the suspension inlet heat transfer tube 3 beyond the suspension outlet heat transfer tube 4. Now, in order to prevent the flow path blockage due to the molten ash connection, the suspension outlet heat transfer tube 4 has an interval between the tube groups of about 450 mm, which is larger than the conventional one. The intermediate header 1 can be arrange | positioned by arrange | positioning so that it may pass between the adjacent heat exchanger tubes in the horizontal direction.

Furthermore, by adopting the structure shown in FIG. 1, the length of the portion of the horizontal heat transfer tube 2 and the suspended inlet heat transfer tube 3 above the ceiling wall tube 12 can be reduced.
As shown in FIG. 6B, which is a cross-sectional view taken along the line GG of the heat transfer tube structure shown in FIG. 8, the ceiling wall tube 12, the horizontal heat transfer tube outlet manifold 8, the ceiling wall tube 12, and the suspended heat transfer tube inlet The manifold 11 has a difference in thermal expansion from the center of the boiler in the direction of the pipe axis of the manifolds 8 and 11 due to the temperature difference during boiler operation. At this time, since the heat transfer tubes 2 and 3 are connected to the headers 7 and 10 connected to the manifolds 8 and 11, respectively, the heat transfer tubes 2 and 3 are forcibly deformed by the difference in thermal expansion between the manifolds 8 and 11. In this case, a large stress is generated in an E portion (FIG. 6B) which is a welded joint between the headers 7 and 10 and the heat transfer tubes 2 and 3.
In the heat transfer tube structure shown in FIG. 8, as shown in FIG. 6B, the manifolds 8 and 11 are arranged about 2500 mm above the ceiling wall 12 from the viewpoint of reducing the stress of the heat transfer tubes 2 and 3, and have a flexible structure. There was a need to adopt.

  On the other hand, since the manifolds 8 and 11 shown in FIG. 7 are not installed if the configuration of the first embodiment is adopted as shown in FIG. The intermediate header 1 moves heat together with the ceiling wall pipe 12. That is, there is no difference in thermal expansion between the intermediate header 1 and the ceiling wall pipe 12.

  Therefore, the heat transfer tubes 2 and 3 connected to the intermediate header 1 do not need to secure flexibility, and the intermediate header 1 may be disposed at a position of about 2000 mm above the ceiling wall tube 12. The length of the upper part of the part which does not contribute to the heat transfer from the pipe 12 at all can be reduced.

Moreover, the installation cost will be only 26 places if the intermediate header 1 is divided | segmented by the C section shown in FIG. 1, and the C section is welded and joined in the field where a boiler is installed.
In the structure shown in FIGS. 7 and 8, there are four welds between the manifolds 8 and 11 and the connecting pipes 9 </ b> A and 9 </ b> B and 52 welds between the headers 7 and 10 and the manifolds 8 and 11. Then, the welding location can be halved, and the installation cost can be reduced and the installation performance can be improved as compared with the structures shown in FIGS.

FIG. 4 is a side view showing the structure of the present embodiment. The difference from the first embodiment is that in order to further improve the transportability, the suspension inlet heat transfer tube 3 is placed on the downstream side of the gas flow in the furnace. The suspension outlet heat transfer tube 4 is arranged on the upstream side of the gas flow in the furnace.
The intermediate header 1 to which the horizontal heat transfer tubes 2 are connected can be arranged without passing through the interval between the adjacent tubes of the suspension outlet heat transfer tubes 4, and the suspension inlet heat transfer tubes 3 connected to the intermediate header 1 are suspended. The suspended heat transfer tube outlet header 5 is connected to the suspended heat transfer tube outlet header 5 through the lowered outlet heat transfer tube 4, and the suspended heat transfer tube outlet header 5 is connected to the suspended heat transfer tube outlet manifold 6.

  This embodiment differs from the configuration of the first embodiment in which the intermediate header 1 passes through the interval between adjacent tubes of the hanging outlet heat transfer tube 4, and the intermediate header 1 passes through the interval between adjacent tubes of the hanging outlet heat transfer tube 4. Therefore, the length of the intermediate header 1 is about 2000 mm shorter than the structure of the first embodiment, and the transportability is improved.

  However, since the suspension outlet heat transfer tubes 4 are arranged on the high temperature side of the furnace gas flow as described above, the temperature of the suspension outlet heat transfer tubes 4 is higher than the temperature of the suspension outlet heat transfer tubes 4 of the first embodiment. Therefore, it is necessary to make the wall thickness of the hanging outlet heat transfer tube 4 thicker than that of the first embodiment.

DESCRIPTION OF SYMBOLS 1 Intermediate header 2 Horizontally placed heat transfer tube 3 Hanging inlet heat transfer tube 4 Hanging outlet heat transfer tube 5 Hanging Heat transfer tube outlet header 6 Hanging Heat transfer tube outlet manifold 7, 10 Header 8 Horizontal heat transfer tube outlet manifold 9A, 9B Connecting piping
11 Hanging Heat Transfer Tube Inlet Manifold 12 Ceiling Wall Tube 13 Plate Type Heat Transfer Tube Group 14 U Type Heat Transfer Tube Group

Claims (3)

 The rear heat transfer section is a suspended heat transfer pipe in which a plurality of heat transfer pipes are hung in the front-rear direction of the boiler, and a plurality of heat transfer tubes that are horizontally placed in the front-rear direction of the rear heat transfer section of the boiler and stacked vertically A horizontal heat transfer tube having a vertical portion vertically extending above the rear heat transfer section and vertically extending between the suspended heat transfer pipe and the horizontal heat transfer pipe through the boiler ceiling wall. Extending the part and connecting the vertical part of the suspended heat transfer tube and the horizontal heat transfer tube above the boiler ceiling wall with an intermediate header to form a set of heat exchange units, a plurality of heat exchange units in the boiler furnace width direction A heat transfer tube structure characterized by a set arrangement.   The suspended heat transfer tubes of the set of heat exchange units are configured such that the heat transfer tubes connected to the intermediate header are bent at the rear side of the boiler below the ceiling wall and folded upward to penetrate the ceiling wall. The heat transfer tube structure according to claim 1, wherein the heat transfer tube structure is connected to an outlet header of a suspended heat transfer tube above the intermediate header so as to straddle the header.   The suspended heat transfer tubes of the pair of heat exchange units are configured such that the heat transfer tubes connected to the intermediate header are bent forward of the boiler below the ceiling wall and folded upward to penetrate the ceiling wall. The heat transfer tube structure according to claim 1, wherein the heat transfer tube structure is connected to an outlet header of a suspended outlet heat transfer tube above the intermediate header so as to straddle the header.

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