JP5129718B2 - Reinforcement structure of the bottom tube - Google Patents

Description

  The present invention relates to a reinforcing structure for a bottom tube of a boiler furnace such as a coal-fired boiler.

The coal-fired boiler furnace has a configuration as shown in FIG. 1, for example. Such a coal-fired boiler furnace burns coal in the boiler furnace 2, the ash generated by burning the coal falls to the bottom, and the dropped ash is directed downward toward the center of the boiler furnace 2. It moves on the inclined furnace bottom wall 3 toward the center, and is configured to be discharged to the outside from a hopper (not shown) provided at the center of the furnace bottom wall 3.
Further, the furnace bottom wall 3 is formed by joining one or a plurality of panels in which a plurality of furnace bottom tubes arranged in parallel are connected by fins.

In such a coal fired boiler furnace 2, adhering ash (hereinafter referred to as a clinker) is present at various locations in the boiler furnace 2 such as the tip of a burner (not shown) for introducing fuel for burning coal into the boiler furnace 2. Occur. If such a clinker is a small lump, even if it falls, no major problem will occur. However, if the clinker that has become a large lump falls, it directly hits the furnace bottom tube forming the furnace bottom wall 3, and the furnace bottom The tube may be damaged or deformed.
In the furnace bottom pipe, heated water containing water vapor flows to generate steam. However, if the furnace bottom pipe is damaged or deformed by the fall of the clinker that has become a large mass, the steam in the furnace bottom pipe The problem of leaking occurs.
When such steam leakage occurs, it is necessary to replace the furnace bottom tube of the leakage part, but in order to replace the furnace bottom tube, it is necessary to stop the operation of the boiler furnace 2, and in terms of time The burden is large in terms of cost. Even if the leakage of the steam does not occur, the leakage may occur if left untreated due to large deformation or thin wall. large.
In addition, the fall of large clinker cannot be prevented unless the properties of the coal are improved, so in coal-fired boilers that are required to burn coal of various properties, the large clinker is prevented from falling. I can't do it.

  Therefore, for the purpose of protecting the furnace bottom tube, a technique in which a reinforcing portion projecting along the tube axis direction is provided on the furnace inner surface of the furnace bottom tube has been put into practical use. It is disclosed. As the reinforcing part, for example, a hexagonal cross-section rod is attached along the furnace bottom tube axis direction, and the furnace bottom tube and a metal alloy welding material are welded to the pipe, along the furnace bottom tube axis direction. For example, planting multiple studs.

  As a result, even if a large clinker falls, the clinker hits the reinforcing part so that the furnace bottom pipe is not easily damaged. For example, even if the reinforcing part is damaged, the furnace bottom pipe should not be damaged. Since no steam leakage occurs, the frequency of replacement of the furnace bottom tube can be kept small. Furthermore, since the reinforcing portion is projected along the tube axis direction, it is possible to crush the large clinker that has been dropped by the reinforcing portion, thereby allowing a plurality of small clinker to fall. The kinetic energy due to can be dispersed and reduced. Therefore, further damage to the furnace bottom tube is less likely to occur.

Japanese Utility Model Publication No. 5-8201

  However, in the technique disclosed in Patent Document 1, the range in which the reinforcing material is provided to provide the reinforcing portion over the entire furnace inner surface of the furnace bottom tube is wide, the cost burden for providing the reinforcing material is large, and further reinforcement There was a problem that the time required to provide the material required a long time, and the construction period required to create the furnace bottom wall was prolonged.

  Therefore, in view of the problems of the prior art, the present invention can prevent the furnace bottom tube from being damaged even if a large clinker is dropped, and further reduce the cost and man-hour required for reinforcing the furnace bottom pipe. An object of the present invention is to provide a reinforcing structure of a bottom tube that can be reduced.

In order to solve the above problems, in the present invention,
The bottom wall of the boiler furnace is formed to be inclined with respect to the horizontal plane, and the bottom wall is formed by joining one or a plurality of panels formed by connecting a plurality of furnace bottom tubes arranged in parallel, In the reinforcing structure of the furnace bottom tube in which a reinforcing member is attached to the furnace inner surface portion of the furnace bottom tube, a support member for supporting the furnace bottom tube is provided on the furnace outer surface portion of the furnace bottom tube. The reinforcing member is attached only to a furnace inner surface portion of a furnace bottom pipe opposite to the furnace bottom wall.

The inventor examined the damage state of the furnace bottom tube when a large clinker was dropped, and obtained the following two findings when a support member was provided on the furnace outer surface of the furnace bottom tube.
(1) Even if a large clinker falls on the furnace bottom tube on the inner surface of the furnace that is not supported by the support member, the furnace deforms and absorbs the kinetic energy due to the clinker dropping. The bottom tube is not easily damaged.
(2) When a large block of clinker falls on the furnace bottom tube on the furnace inner surface of the portion supported by the support member, the panel is restrained by the support member, so that the kinetic energy due to the fall of the clinker Can hardly be absorbed and the bottom tube is easily damaged.

  Therefore, based on the knowledge of (1) and (2) above, the furnace outer surface portion of the furnace bottom tube that is easily damaged by the drop of a large clinker, that is, the support member that supports the furnace bottom tube is the furnace bottom wall. By attaching the reinforcing member only to the inner surface portion of the furnace bottom tube on the opposite side, the furnace bottom tube can be prevented from being damaged even when a large clinker is dropped. Furthermore, since the attachment range of the reinforcing member is narrow, the cost and man-hours required for reinforcement can be reduced.

Further, the support member is a rod-shaped member, and the reinforcing member is attached in a range of about three times the short direction length of the support member with the short direction of the support member as a center.
The rod-like member here means a member that is straight and has an elongated shape, and the cross-sectional shape is not particularly limited. Examples of rod-shaped members include H-shaped steel, I-shaped steel, L-shaped steel, round bars, square bars, and the like.

  The location where the large clinker is greatly damaged is the position supported by the support member as described in the above (2), but the position where the support member is not present is also the position where the support member is present nearby. In comparison with the above, the presence of the support member makes it difficult for the panel to be deformed, so that it is difficult to absorb the kinetic energy due to the fall of a large clinker, and the furnace bottom tube is easily damaged. Therefore, the range in which the reinforcing member is attached not only on the side opposite to the support member but also in a range approximately three times the short direction length of the support member with the short direction of the support member as the center. It is possible to prevent the furnace bottom tube from being damaged.

Further, the reinforcing member is a member that continuously protrudes along the axial direction of the furnace bottom tube, and has a smaller diameter than the diameter of the furnace bottom tube.
By making the reinforcing member smaller in diameter than the furnace bottom tube, when a large clinker falls, the load concentrates on the small diameter reinforcing member, destroys the clinker, and disperses the kinetic energy due to the clinker dropping In addition, it is possible to prevent the reinforcing member from hindering the cooling of the furnace bottom wall by the heated water flowing in the furnace bottom pipe.

Further, the reinforcing member is a plurality of protrusions arranged in parallel at a constant interval along the axial direction of the furnace bottom tube, and the protrusions are studs welded to the tube by stud welding. It is characterized by that.
Thereby, the attachment of the reinforcing member can be performed in a shorter time.

Further, the interval between the protrusions is made smaller than the interval between the furnace bottom tubes.
If the distance between the protrusions is large, the clinker may hit directly between the protrusions depending on the shape of the large clinker. However, by defining the distance between the protrusions, the clinker is between the protrusions. Can be prevented from hitting directly.

Further, the projection has a columnar shape with a bottom portion as an attachment portion to the furnace bottom tube, and the height of the columnar projection is less than three times the diameter.
Thereby, when the large clinker hits the projection, it is possible to prevent the projection from being bent by a buckling phenomenon due to axial compression.

  As described above, according to the present invention, the bottom tube can be prevented from being damaged even if a large clinker is dropped, and the cost and man-hour required for reinforcing the bottom tube can be reduced. Therefore, it is possible to provide a reinforcing structure for a furnace bottom tube.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

(Constitution)
The configuration of the coal fired boiler furnace will be described with reference to FIG.
FIG. 1 is a perspective view of a coal-fired boiler furnace, which is the same as the conventional one except for a reinforcing structure of a furnace bottom tube described later.
Such a coal-fired boiler furnace 2 combusts coal in the boiler furnace 2, the ash generated by burning the coal falls to the bottom, and the dropped ash is directed downward toward the center of the boiler furnace 2. It moves to the center direction on the furnace bottom wall 3 inclined to the center, and is discharged to the outside from a hopper (not shown) provided in the center of the furnace bottom wall 3.

Next, the structure of the furnace bottom wall 3 is demonstrated using FIG.2, FIG3 and FIG.4.
FIG. 2 is a perspective view of the panel 4 constituting the furnace bottom wall 3 as viewed from the inside of the boiler furnace 2, and FIG. 3 is a perspective view of the panel 4 constituting the furnace bottom wall 3 as viewed from the outside of the boiler furnace 2. FIG. FIG. 4 is a partial cross-sectional view of the panel 4 constituting the furnace bottom wall 3.

The furnace bottom wall 3 is formed by joining a plurality of panels 4. The panel 4 is formed by connecting a plurality of furnace bottom tubes 40 arranged side by side with fins 42 as shown in FIG. The furnace bottom tube 40 may be directly connected without being connected by fins.
Further, the plurality of furnace bottom tubes 40 constituting the panel 4 are H-shaped steels arranged in a direction substantially perpendicular to the tube axis direction of the furnace bottom tube 40 on the furnace outer surface portion as shown in FIGS. 2 and 3. It is supported by the direction frame 6. 2 and 3, the bottom tube 40 is supported by the two horizontal frames 6, but one or three or more horizontal frames 6 may be used depending on the size of the bottom wall 3 or the like. May be used.
Further, the horizontal frame 6 is supported by a vertical frame 8 which is an H-shaped steel disposed along the tube axis direction of the furnace bottom tube 40.

  The panel 4 configured as described above includes various parts in the boiler furnace 2 such as a tip of a burner (not shown) for introducing fuel for burning coal into the boiler furnace 2 as shown in FIGS. The clinker 10 generated in step 1 falls.

(analysis)
Analysis was performed on damage to the furnace bottom tube 40 when the clinker 10 dropped on the panel 4 constituting the furnace bottom wall 3 as described above.
This analysis used the panel 4, the horizontal frame 6, the vertical frame 8, and the clinker 10 as plate elements, and used a finite element method (FEM) analysis.

FIG. 5 shows a schematic diagram of FEM analysis conditions. FIG. 5 is a schematic view of the furnace bottom wall shown in a perspective view in FIGS. 2 and 3 as viewed from the side. As shown in FIGS. 5A and 5B, the furnace bottom tube 40 was inclined by an angle θ with respect to the horizontal plane, and the clinker 10 was dropped on the furnace bottom tube 40 for analysis. The angle θ was set to 50 °, similar to the inclination angle of the furnace bottom wall in a normal boiler furnace.
Under the analysis conditions shown in FIG. 5 (A), the clinker 10 was dropped almost in the middle of the two lateral frames 6 and the deformation state of the panel 4 and the furnace bottom tube 40 at that time was analyzed.
Under the analysis conditions shown in FIG. 5B, the clinker 10 was dropped on the horizontal frame 6 and the deformation state of the panel 4 and the furnace bottom tube 40 at that time was analyzed.
The analysis was performed when the weight of the clinker 10 was dropped from a height of 30 m for four types of 37 kg, 89 kg, 173 kg, and 300 kg. The results are shown in Table 1.

  In Table 1, the center of the panel at the drop position is a large clinker 10 on the panel 4 on the furnace inner surface between the horizontal frames 6 that are not supported by the horizontal frame 6 as shown in FIG. This means that the clinker 10 has fallen on the panel 4 on the furnace inner surface of the portion supported by the horizontal frame 6 as shown in FIG. 5B. Represents that.

From Table 1, it can be seen that the support portion has a larger amount of collapse of the tube than the center portion of the panel, and is easily damaged. Furthermore, depending on the weight of the clinker, the breaking displacement of the tube may be exceeded. Here, the breaking displacement of the pipe is 18 mm, and it can be seen that dropping the 89 kg clinker at this time exceeds the breaking displacement of the pipe.
The reason why the crushed amount of the support portion does not increase with the increase in the weight of the clinker is that the size of the clinker increases with the increase in the weight of the clinker, and the deformation region of the tube is widened.

The above FEM analysis results were summarized and the following findings were obtained.
(I) The following knowledge was obtained from FEM analysis under the analysis conditions shown in FIG.
When a large mass of clinker 10 falls on the panel 4 on the inner surface of the furnace between the lateral frames 6 not supported by the lateral frame 6, the panel 4 deforms and absorbs the kinetic energy due to the fall of the clinker 10. Therefore, the furnace bottom tube 40 is hardly damaged.
(Ii) The following findings were obtained from the FEM analysis under the analysis conditions shown in FIG.
Even if a large block of clinker 10 falls on the panel 4 on the furnace inner surface of the portion supported by the lateral frame 6, the panel 4 is restrained by the lateral frame 6. The furnace bottom tube 40 can be easily damaged because the kinetic energy due to the fall of the tube can hardly be absorbed, and the amount of collapse of the tube may exceed the fracture displacement depending on the weight of the clinker falling.

  From the above, the outer surface of the furnace bottom tube 40 that is easily damaged by the drop of the large clinker 10, that is, the lateral frame 6 that supports the furnace bottom tube 40 is opposite to the panel 4. It has been found that if the reinforcing member is attached to the surface portion of the furnace bottom tube 40 at the position, damage to the furnace bottom tube 40 can be prevented even if the large clinker 10 is dropped.

FIG. 6 is a side view and an upper plan view of the panel 4 forming the furnace bottom wall 3 in the first embodiment.
Since it is the same as the panel 4 shown in FIG.2 and FIG.3 except the reinforcement rod 12 mentioned later, description is abbreviate | omitted. In FIG. 6, the vertical frame 8 is not shown.
In the first embodiment, the reinforcing rod 12 is attached to the furnace inner surface portion of the furnace bottom tube 40 which is the position opposite to the panel 4 with respect to the lateral frame 6 based on the above knowledge. Compared with the position where the horizontal frame 6 does not exist in the vicinity, the presence of the horizontal frame 6 makes it difficult for the panel 4 to be deformed and the furnace bottom tube 40 may be damaged. The reinforcing rod 12 was attached in the width direction over a range twice the width of the lateral frame 6. That is, the range indicated by reference numeral 16 in FIG. 6 is the attachment range of the reinforcing rod.
The reinforcing rod 12 is a rod-like member that is continuously attached along the axial direction of the furnace bottom tube 40. The shape of the reinforcing rod is not particularly limited as long as it is a rod-like member that is continuously attached along the axial direction of the furnace bottom tube 40 as described above, but is a rod-like hexagonal rod having a hexagonal cross section or a circular cross section. A rod-like round rod or the like can be exemplified.

  7 is a cross-sectional view taken along line AA in FIG. 6, FIG. 7A is a case where a hexagonal rod having a hexagonal cross section is used as the reinforcing rod 12, and FIG. 7B is a round bar having a circular cross section. It is a figure at the time of using a rod as the reinforcing rod 12. FIG.

  As shown in FIGS. 7A and 7B, the reinforcing rod 12 is welded to the furnace bottom tube 40 by welding material 16 regardless of whether it has a hexagonal cross section or a circular cross section. .

As a result, when the large clinker 10 falls to a position where the reinforcing rod 12 in the vicinity of the lateral frame 6 is present, the clinker 10 hits the reinforcing rod 12 and the furnace bottom tube 40 is hardly damaged. Further, since the large clinker dropped by the reinforcing rod 12 is crushed into a plurality of small clinker, the kinetic energy caused by the large clinker dropping is dispersed and reduced, thereby preventing the furnace bottom tube 40 from being damaged. can do.
If the diameter of the reinforcing rod 12 is smaller than the diameter of the furnace bottom tube 40, when the large clinker 10 is dropped, the load is concentrated on the small diameter reinforcing rod 12, and the clinker 10 is destroyed. It is possible to easily disperse the kinetic energy due to the falling of the water and to prevent the reinforcing rod 12 from interfering with the cooling of the furnace bottom wall 3 by the heated water flowing in the furnace bottom pipe 40.

Further, as for the position where the reinforcing rod 12 in the vicinity of the lateral frame 6 does not exist (the range other than indicated by 16 in the right diagram of FIG. 6), the furnace bottom tube is hardly damaged as described above (i).
That is, it can be said that the reinforcing structure of the furnace bottom tube 40 is less likely to damage the furnace bottom tube 40 throughout the furnace bottom tube 40.

  Furthermore, as is clear from FIG. 6, it is not necessary to attach the reinforcing rod 12 over the entire furnace bottom tube 40 and the attachment range of the reinforcing member is narrow, so that the cost and man-hours required for attaching the reinforcing rod can be reduced. it can.

The reinforcing structure of the furnace bottom tube 40 in Example 1 was evaluated using FEM analysis.
In the FEM analysis, it was assumed that the clinker was a rigid sphere, and the clinker collided with the furnace bottom tube near the lateral frame.
The clinker and furnace bottom tube were set as analysis conditions as follows.
Clinker: Diameter 300mm, weight 37kg
Furnace bottom tube: tube outer diameter 38.1 mm, plate thickness 4 mm
Furnace bottom tube interval: 51 mm
The reinforcing rod was analyzed for three types having a rectangular cross section: height H5 mm × plate thickness t5 mm, height H10 mm × plate thickness t10 mm, height H15 mm × plate thickness t15 mm.

  The analysis results are shown in Table 2.

  From Table 2, it is clear that the amount of local collapse of the furnace bottom tube is reduced by attaching the reinforcing rod 12. If the amount of local collapse of the furnace bottom tube exceeds 18 mm, the furnace bottom tube will be damaged, so there is a risk of damage if there is no reinforcing rod, but in this embodiment there is no risk of damage to the furnace bottom tube. I can say that.

In the second embodiment, the reinforcing member is different from the first embodiment. Other configurations and the attachment range of the reinforcing member are the same as those in the first embodiment described with reference to FIGS.
FIG. 8 is a partial perspective view of the furnace bottom tube in the second embodiment, and FIG. 9 is another partial perspective view of the furnace bottom tube in the second embodiment.

As shown in FIGS. 8 and 9, a plurality of cylindrical studs 14 are arranged in parallel in the furnace bottom tube 40 at regular intervals along the axial direction of the furnace bottom tube 40. 14 is welded to the furnace bottom tube 40 by stud welding. As shown in FIG. 8, a plurality of rows (three rows in FIG. 8) of the studs 14 arranged side by side may be arranged, or only one row may be arranged as shown in FIG.
This makes it possible to attach the reinforcing member in a short time and to prevent the furnace bottom tube 40 from being damaged by the clinker.

  In addition, if the distance between the studs is large, the clinker may hit directly between the studs depending on the shape of the falling large clinker. Since it is necessary to attach a large amount of studs if the interval between them is too small, the stud interval may be determined according to the properties of the coal burned in the coal-fired boiler.

  Moreover, it is preferable to make the said stud into the column-shaped shape which makes the bottom part the attachment part to the furnace bottom pipe 40, and to make height into 2 to 3 times the diameter. If the stud height is 3 times or less of the diameter, it is possible to prevent the stud from being bent due to a buckling phenomenon due to axial compression when a large clinker hits the stud 14. This is because the function as a reinforcing material is sufficiently exhibited when the ratio is twice or more.

  Can be used as a bottom tube reinforcement structure that can prevent damage to the bottom tube even when a large clinker falls, and can reduce the cost and man-hours required to reinforce the bottom tube. can do.

It is a perspective view of a coal fired boiler furnace. It is the perspective view which looked at the panel which comprises a furnace bottom wall from the internal direction of a boiler furnace. It is the perspective view which looked at the panel which comprises a furnace bottom wall from the external direction of a boiler furnace. It is a partial cross section figure of the panel which constitutes a furnace bottom wall. It is the schematic of FEM analysis conditions. It is the side view and upper top view of the panel which form the furnace bottom wall in Example 1. It is AA sectional drawing in FIG. 6 is a partial perspective view of a furnace bottom tube in Example 2. FIG. FIG. 10 is another partial perspective view of the furnace bottom tube in the second embodiment.

Explanation of symbols

2 Boiler furnace 3 Furnace bottom wall 4 Panel 6 Horizontal frame 8 Vertical frame 10 Clinker 12 Reinforcing rod 14 Stud 40 Furnace bottom tube 42 Fin

Claims (6)

While forming the bottom wall of the boiler furnace to be inclined with respect to the horizontal plane,
The furnace bottom wall is formed by joining one or more panels configured by connecting a plurality of furnace bottom tubes arranged in parallel,
In the reinforcing structure of the furnace bottom tube in which a reinforcing member is attached to the furnace inner surface portion of the furnace bottom tube,
A support member for supporting the furnace bottom tube is provided on the furnace outer surface portion of the furnace bottom tube,
A reinforcing structure of a furnace bottom tube, wherein the reinforcing member is attached only to a furnace inner surface portion of a furnace bottom tube opposite to the furnace bottom wall with respect to the support member. The support member is a rod-shaped member,
The reinforcing structure of a furnace bottom tube according to claim 1, wherein the reinforcing member is attached in a range approximately three times as long as the length of the support member in the short direction of the support member.   3. The furnace bottom tube according to claim 1, wherein the reinforcing member is a member that continuously protrudes along an axial direction of the furnace bottom tube, and has a diameter smaller than the diameter of the furnace bottom tube. Reinforcement structure.   The reinforcing member is a plurality of protrusions arranged in parallel along the axial direction of the furnace bottom tube, and the protrusions are studs welded to the tube by stud welding. The reinforcing structure of a furnace bottom tube according to claim 1 or 2, characterized in that   The reinforcing structure of a furnace bottom tube according to claim 4, wherein an interval between the protrusions is made smaller than an interval between the furnace bottom tubes. The protrusion is a cylindrical shape having a bottom portion as an attachment portion to the furnace bottom tube,
6. The furnace bottom tube reinforcing structure according to claim 4, wherein a height of the cylindrical projection is less than three times the diameter.

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