JPS5847345Y2 - Plate spacer - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a plate-shaped spacer that connects adjacent tubes in a group of heat exchanger tubes such as a boiler economizer.

In addition to temporary spacers, there are flexible spacers, band-type spacers, etc., but plate-type spacers have the advantage of being the simplest and cheapest in structure compared to other spacers, as well as being the most secure in binding the tubes together. It has been widely used since.

A conventional plate spacer will be explained based on FIG.

A plate-shaped spacer 1 having a rectangular plane is arranged between the tubes 2, and the portions where the plate-shaped spacer 1 and the tubes 2 come into contact are welded.

When the plate spacer 1 is exposed to high-temperature combustion gas, the temperature of the tube wall metal in the area where the plate spacer 1 and the pipe 2 are welded becomes considerably higher than the tube wall temperature in the area where the plate spacer 1 is not attached. Welded installation may cause localized high-temperature corrosion and thinning of the pipe.
When the plate spacer 1 is placed, forced vibration of the tube 2 occurs, and vibration stress is generated in the welded portion of the plate spacer 1 accordingly.

In addition, when installing the block-shaped spacer 1, thermal stress is induced in the welded part due to the thermal expansion difference between the tube rows of the tube group, and when combined with the vibration stress mentioned above, the spacer installation causes cracks from the welded part, and in some cases, the pipe This may lead to a leakage accident.

This is due to the following points.

1 The rectangular plate spacer 1 is exposed to combustion gas and has a large area, so it has the function of a kind of fin, and the welded part between the plate spacer 1 and the pipe 2 becomes high temperature, causing fatigue of the welded part. Reduce strength.

2 Since the plate-shaped spacer 1 has a rectangular shape, the plate-shaped spacer has a large rigidity, so there is a difference in the rigidity ratio between the plate-shaped spacer 1 and the pipe 2, which tends to cause large stress concentration in the welded portion.

Therefore, the present invention has been made with the object of eliminating the drawbacks of conventional plate spacers and providing a plate spacer which is extremely practical and economical.

The present invention provides a plate-shaped spacer which is arranged between the tubes in a heat exchanger tube group so as to interconnect the tubes, and whose end portions in contact with the tubes are welded to the outer wall of the tubes. The present invention provides a plate-shaped spacer characterized in that a notch is provided on the end side located between the spacer and the pipe.

Next, the present invention will be explained based on an embodiment shown in FIGS. 2 and 3.

The plate-shaped spacer 11 has a U- or V-shaped notch cut out on both sides of a conventional rectangular spacer, that is, the edge between the tubes 12.
The center part of the plate spacer 11 is constricted, and the four corners of the plate spacer 11 are provided with vertical parts having dimensions approximately equal to the leg length of the fillet weld for welding the plate spacer 11 to the tube 12. It has been established.

By cutting both sides of the plate spacer 11, the heat receiving area due to radiation and convection heat transfer of the plate spacer 11 is reduced. , compared to conventional plate spacers, the temperature is lower and local high-temperature corrosion on the tube wall is reduced, and the metal temperature of the plate spacer 11 is lowered overall, so the metal temperature difference between the plate spacer 11 and the tube 12 is reduced. As a result, the attachment of the plate spacer 11 also reduces the thermal stress at the weld.

Furthermore, by configuring the vertical portions of the four corners of the plate spacer 11 to be approximately equal to the welding leg length, and by appropriately selecting the slope of the contour line of the cut portion of the plate spacer 11, the plate spacer 11 is welded to the pipe 12. When the plate spacer 11 and the pipe 12 are attached to each other, the stress concentration at the welded part is significantly alleviated, and the low cycle thermal fatigue strength and The fatigue limit against forced vibration due to combustion gas flow has been dramatically improved,
By constricting the center of the plate spacer 11, the bending and torsion of the plate spacer 11 itself are inevitably reduced, so thermal stress and vibration stress generated at the welded portion of the plate spacer 11 are reduced. reduce

Furthermore, even if an excessive load is applied, it is possible to break the plate spacer 11 at its constriction, thereby preventing damage to the tube wall portion or leakage of the tube.

Although the present invention has been described above based on one embodiment, the present invention is not limited to this embodiment. The pipe is arranged in the tube, and the end portion in contact with the tubes is attached to a plate spacer welded to the outer wall of the tube, and a cutout portion is provided on the end side located between the tubes. We offer plate spacers.

According to the plate spacer provided by the present invention, the heat receiving area due to radiation and convection heat transfer of the spacer is reduced by providing notches on both ends, so the plate spacer itself and the installation of the spacer are The metal temperature of the welded part is
As the temperature becomes lower, localized high-temperature corrosion on the tube wall is reduced, and the overall metal temperature of the plate spacer is lowered, the metal temperature difference between the spacer and the tube is reduced, and as a result, the spacer installation is performed at the welded part. Thermal stresses are also reduced.

Furthermore, by forming a notch in the plate spacer to make it narrower, the bending and torsional rigidity of the plate spacer itself is inevitably reduced, which reduces the thermal stress and vibration stress generated at the welded part of the plate spacer. In addition, even if an excessive bulge load is applied, the spacer can be ruptured at the constriction part to prevent damage to the pipe wall or leakage of the pipe.

[Brief explanation of the drawing]

FIG. 1 is a front view of a conventional plate spacer, FIG. 2 is a front view of an embodiment of the present invention, and FIG. 3 is a view taken along the line X--X in FIG. 1.11...Plate spacer, 2,12...
··tube.

Claims (1)

[Scope of utility model registration request] A plate-shaped spacer that is disposed between the tubes in a heat exchanger tube group so as to interconnect the tubes, and whose end portions in contact with the tubes are welded to the outer wall of the tubes, between the tubes. A plate-shaped spacer characterized by having a cutout portion on the end side located at.