JP2006226577A - Heat transfer pipe cover plate structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat transfer pipe cover plate structure having sufficient strength on a welding portion between a cover plate grasping a heat transfer pipe for preventing the drop of a mounting band from the wear prevention cover plate of the heat transfer pipe, and the mounting band, and easily removing the mounting band welding portion in demounting the cover plate. <P>SOLUTION: In this heat transfer pipe cover plate structure composed of the mounting band 3 grasping an outer peripheral pipe 1 of the heat transfer pipe 1, one axial end face of the cover plate 2 is fillet-welded to the heat transfer pipe 1, the mounting band 3 is composed of a curved portion 3a formed to be fitted to the outer peripheral face of the heat transfer pipe 1 at the other axial end of the cover plate 2, and linear portions 3b extending from both sides of the curved portion 3a in the circumferential direction, inner faces of the linear portions 3b are kept into contact with the outer edge of the side face 2a of the cover plate 2, and further a V-shaped groove formed between the tip of each linear portion 3b and a cover plate end is welded. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat transfer tube cover plate structure that prevents wear of a heat transfer tube installed in a boiler or protects a reduced thickness portion, and in particular, improves the strength of a welded portion that connects a cover plate that holds the heat transfer tube and a mounting band. The present invention relates to a structure suitable for securing.

  A cover plate is installed in a part of the heat transfer tubes such as a suspended superheater, a reheater, a horizontal heater, and a horizontal reheater installed in the boiler. This cover plate prevents the surface of the heat transfer tube from being worn by steam sprayed from a soot blower installed in the vicinity of the heat transfer tube, or protects the reduced thickness portion of the heat transfer tube that needs to be replaced at the next periodic inspection. Mounted for etc. The cover plate is made of a semi-cylindrical member matched to the outer peripheral surface of the heat transfer tube, and is joined to the heat transfer tube by fillet welding at one axial end surface thereof.

  On the other hand, the thickened surface in the busbar direction at the other end in the axial direction of the cover plate is butt welded to a short semi-cylindrical mounting band attached to the cover plate across the heat transfer tube. It is gripped by a cylinder formed by the other axial end of the cover plate and a mounting band. However, since the cover plate and the mounting band are semi-cylindrical with the same bending shape along the outer surface shape of the heat transfer tube, the weld groove shape of the joining portion of the cover plate and the mounting band is I-type, that is, butt welding, and the welding Care must be taken not to melt into the outer surface of the heat transfer tube, and therefore it is not a full penetration weld.

  For this reason, depending on the welding work situation of butt welding, the cover plate and the mounting band may be connected only at a relatively shallow portion of the surface, in which case the difference in thermal expansion between the heat transfer tube and the cover plate (both corners) The heat transfer tube and the cover plate are each thermally stretched starting from the wall welding), and the butt weld is damaged by the vibration of the heat transfer tube and the mounting band may drop off. After the drop off, the cover plate is no longer restricted by the mounting band to the heat transfer tube, so that the cover plate is deformed during the heat extension in the direction other than the heat transfer tube axis starting from the fillet weld. It will no longer play the role of preventing wear or protecting the heat transfer tube thickness reduction part. Even when it is necessary to remove the cover plate, it is necessary to pay close attention not to damage the heat transfer tube by a grinder or the like when removing the welded portion between the cover plate and the mounting band.

  As another conventional technique, there is the following heat transfer tube wear prevention device. This device is used in a fluidized bed boiler and is fitted with a semi-cylindrical protector that is attached to half of the outer peripheral surface of the heat transfer tube, and the protector is fitted on the remaining half of the heat transfer tube at each end in the longitudinal direction of the protector. And a welding stud for fixing the mounting band and the protector to the heat transfer tube. According to this apparatus, the protector can be easily assembled without welding work, the risk of dropping off can be eliminated, and repair and replacement can be facilitated. (For example, see Patent Document 1)

  As another conventional technique, a ceramic protective cover for a welded portion of a metal pipe is disclosed. This ceramic protective cover protects the butt welds of metal pipes installed inside boilers, etc. from high-temperature oxidation, corrosion, and wear. The cylindrical body that fits outside the metal pipes is divided in half in the axial direction. Consists of the body. The pair of divided bodies have a groove extending in the axial direction on their mating surfaces and a protruding line adjacent to the groove, and the groove and the protruding line of one divided body are fitted into the other protruding line and the groove. To form a cylindrical body. However, there is no description of a method for fixing the ceramic protective cover to the metal tube. (For example, see Patent Document 2)

Japanese Utility Model Publication No. 60-139101 (pages 3-6, FIGS. 1 and 5) Japanese Utility Model Publication No. 62-193987 (page 3-4, FIGS. 1 and 2)

  The above prior art does not give sufficient consideration to the joint welding of the cover plate and the mounting band, and the cover plate is deformed after the welded portion is broken and the mounting band falls off, and the cover plate and the heat transfer tube There is a problem that a gap is formed between the two and the prevention of wear or protection of the heat transfer tube thickness reduction portion. In addition, it was necessary to remove the cover plate, and when removing the butt weld between the cover plate and the mounting band with a grinder or the like, it was necessary to be careful not to damage the heat transfer tube.

  The object of the present invention is to sufficiently provide the strength of the welded portion between the cover plate and the mounting band for gripping the heat transfer tube in order to prevent the mounting band from falling off the cover plate for preventing the heat transfer tube from being worn, It is another object of the present invention to provide a heat transfer tube cover plate structure in which it is easy to remove the attachment band weld when it is necessary to remove the cover plate.

  In order to achieve the above object, the heat transfer tube cover plate structure of the present invention includes a semi-cylindrical cover plate installed in accordance with the outer peripheral surface of the heat transfer tube, and a position facing the cover plate and the heat transfer tube. And an attachment band for holding the heat transfer tube in cooperation with the cover plate, one end surface of the cover plate in the axial direction is fillet welded to the heat transfer tube, and the attachment band is a shaft of the cover plate. A curved portion that is positioned at the other end in the direction and is formed to fit the outer peripheral surface of the heat transfer tube, and linear portions that extend in the circumferential direction from both circumferential ends of the curved portion, and an inner surface of each linear portion Is formed opposite to the outer peripheral surface of the end portion in the circumferential direction of the cover plate to form a V-shaped groove, and the V-shaped groove is groove-welded.

  According to the structure as described above, the V-shaped groove can be sized according to the required welding strength by adjusting the length of the tip of the straight part of the mounting band. It is possible to obtain a welded portion that is sufficient to prevent this. Further, in the V-shaped groove, since the circumferential end of the cover plate covers the heat transfer tube, it is necessary to remove the cover plate, and when removing the weld between the cover plate and the mounting band, for example, a grinder The surface of the heat transfer tube is not damaged by the removal work.

  According to the present invention, it is possible to prevent the mounting band from dropping from the cover plate for preventing wear of the heat transfer tube by sufficiently giving the strength of the welded portion of the cover plate and the mounting band that grips the heat transfer tube, Further, when it is necessary to remove the cover plate and the welded portion between the cover plate and the mounting band is removed, the removal operation can be easily performed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a heat transfer tube cover plate structure according to the present invention will be described with reference to the drawings. FIG. 1 shows a heat transfer tube cover plate structure of the present embodiment, and FIG. 2 shows a welding connection of an attachment band for attaching the cover plate to the heat transfer tube in the AA sectional view of FIG. FIG. 3 is a conceptual diagram schematically showing the arrangement of the heat transfer tubes 1 in the boiler and the attachment state of the cover plate 2 that protects the heat transfer tubes.

  As shown in FIGS. 1 and 2, the heat transfer tube cover plate structure of the present embodiment includes a cover plate 2 attached to the outer peripheral surface of the heat transfer tube 1, and the heat transfer tube 1 in cooperation with the cover plate 2. It is comprised from the attachment band 3 to hold | grip. The cover plate 2 is a semi-cylindrical member formed to fit the outer peripheral surface of the heat transfer tube 1, and one end surface in the axial direction is fillet welded to the outer peripheral surface of the heat transfer tube 1. 4, the position of the cover plate 2 with respect to the heat transfer tube 1 is fixed. The attachment band 3 is located at the other end in the axial direction of the cover plate 2 so as to face the cover plate 2 with the heat transfer tube interposed therebetween, and the bending portion 3a formed to fit the outer peripheral surface of the heat transfer tube 1 and the curve It is a member which consists of the linear part 3b extended in the circumferential direction from the circumferential direction each side end of the part 3a. The straight portion 3b of the attachment band 3 has an inner surface side (a surface side facing the heat transfer tube 1) that is in contact with the radial outer edge of the circumferential side surface 2a of the cover plate 2 and further extends therefrom, and a tip portion of the straight portion 3b. A V-shaped groove extending in the axial direction is formed between the outer peripheral surface in the vicinity of the circumferential side surface 2a of the cover plate 2, and this V-shaped groove is groove-welded to form a groove weld portion 5. .

  The radial outer edge of the circumferential side surface 2a and the inner surface of the straight portion 3b do not necessarily need to be in contact with each other if a weldable V-shaped groove is formed therebetween.

  As described above, since the groove is provided between the front end portion of the mounting band 3 and the side portion of the cover plate 2, it is possible to adjust the size of the groove by changing the length of the front end portion of the linear portion 3b. High welding strength can be obtained. Further, in this groove, the side portion of the cover plate 2 covers the heat transfer tube 1 by the thickness of the cover, so that there is almost no possibility of melting to the heat transfer tube 1 during groove welding. By the way, in the case of the conventional I-shaped groove, the gap between both the butted members reached the outer surface of the heat transfer tube 1, so that it was easy for melting. If the V-shaped groove as described above is formed and welded, there is no need to worry about welding penetration into the heat transfer tube 1, and the need to pay attention to the penetration is greatly reduced, and the welding operation is facilitated.

  When it is necessary to remove the cover plate 2 from the heat transfer tube 1, the groove weld 5 that joins the cover plate 2 and the attachment band 3, that is, the V-shaped groove weld, sandwiches the cover plate 2. Since it is separated from the heat transfer tube 1, it is possible to easily remove the groove weld 5 and remove the attachment band 3. Since the fear of damaging the heat transfer tube when removing the groove weld 5 is reduced, the removal work can be smoothly advanced. Further, since the groove welded portion (V-shaped groove welded portion) 5 is separated from the heat transfer tube 1 with the cover plate 2 sandwiched therebetween, the attachment band 3 and the heat transfer tube 1 are not welded. 3 can move relative to the heat transfer tube 1, and this relative movement can absorb the difference in thermal expansion between the heat transfer tube and the cover plate starting from the fillet welded portion of the axial end surface of the cover plate 2. is there.

It is a front view which shows embodiment of the heat exchanger tube cover plate structure which concerns on this invention. It is AA sectional drawing of FIG. It is a figure which shows typically arrangement | positioning of the heat exchanger tube in a boiler can, and attachment of the cover plate which protects a heat exchanger tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat transfer tube 2 Cover plate 3 Mounting band 3a Curved part 3b Straight line part 4 Fillet weld part 5 Groove weld part

Claims (1)

A semi-cylindrical cover plate installed in accordance with the outer peripheral surface of the heat transfer tube, and an attachment band that holds the heat transfer tube in cooperation with the cover plate at a position facing the cover plate and the heat transfer tube A heat transfer tube cover plate structure comprising: one end surface of the cover plate in the axial direction is fillet welded to the heat transfer tube, and the mounting band is located at the other end in the axial direction of the cover plate. The curved portion is formed to fit the outer peripheral surface of the heat pipe and linear portions extending in the circumferential direction from both circumferential ends of the curved portion, and the inner surface of each linear portion is the outer periphery of the circumferential end portion of the cover plate A heat transfer tube cover plate structure in which a V-shaped groove is formed between the two facing the surface, and the V-shaped groove is groove welded.

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