JP2017211144A - Method of manufacturing feed water preheater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a feed water preheater that consists of a heat exchanger constituted by coupling a fin tube by a 180° bend pipe, and that can be made lightweight and enables jigs to be used in common.SOLUTION: A pair of two fin tube jigs 12 provided with grooves for supporting fin tubes at constant intervals in a longer direction are used to couple the fin tubes by a U-shaped bend pipe, the fin tubes 3 are set in grooves of the fin tube jigs 12 arranged in parallel, and a press plate 13 is arranged on the opposite side of the fin tubes 3 from the grooves of the fin tube jigs 12 so as to hold the fin tubes 3 with the fin tube jigs 12 and press plate 13, which is repeated as many times as a predetermined number of stages so as to fix the positions of the fin tubes. Then fin tube ends are coupled by the U-shaped bend pipe, and after the fin tubes are completely coupled, the press plate and fin pipe jigs are extracted from the fin tube group.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a feed water preheating device configured by connecting a large number of fin tubes.

As described in Japanese Patent Application Laid-Open No. 10-96504 and Japanese Patent Application Laid-Open No. 2013-108643, in boilers, water supply preheating is widely performed by exchanging heat between boiler feed water and combustion exhaust gas. The feed water preheating device has a large number of fin tubes installed in the exhaust gas passage extending in a direction intersecting with the exhaust gas flow, and the boiler feed water is passed through the fin tubes so that the exhaust gas flowing around the fin tubes flows in the fin tubes. Heat exchange is performed between boiler feeds. The fin tube in such a feed water preheating device generally forms a long flow path by connecting ends with a 180-degree U-bend pipe, and boiler feed water is one of the flow paths by the fin tube. From one end to the other end, it is made to flow while being folded many times along the way.

When assembling this water supply preheating device, when connecting a plurality of fin tubes with bend pipes, the fin tubes are attached to the tube plate and casing (casing, etc.) of the heat exchanger, and the bend pipes are attached to the tips of the fin tubes. We are trying to weld. In assembling, first, a tube sheet with a large number of holes is placed, all fin tubes are inserted into the holes in the tube sheet, and a tube sheet guide jig is inserted into the end of the fin tube. Then, after assembling and temporarily attaching the tube plate, the upper tube plate, and the side plate, the tube plate guide jig is removed. Next, a 180 ° U-bend pipe is welded to the end of the fin tube. When connecting a U-shaped bend tube to a fin tube, it is necessary to fix the position of the fin tube first, and for that purpose, the fin tube, the tube plate, and the side plate are assembled. In addition, since the manufacturing accuracy can be improved and the time can be shortened by using a jig during such manufacturing, the jig is used for manufacturing. However, when the length of the fin tube and the number of installed tubes are different for each model, a jig is necessary for each model, and the jig is manufactured while replacing the jig according to the model. Also, when handling the workpiece in the welding process, there is a problem that it is difficult to handle because the total weight of the workpiece and the jig is heavy.

Moreover, in the invention described in Japanese Patent Laid-Open No. 10-96504, a manufacturing method is described in which a straight fin-shaped fin tube is bent into a meandering fin tube. In this case, the fin-like members are divided into a plurality of groups on the straight tubular fin tube, and fixed at a predetermined interval between the fin-like member groups, and the locations without the fin-like members are alternately reversed. The fin tube has a shape meandering in a planar manner. In this case, it is not necessary to weld the vent pipe, but the fin tube on which the fin-like member is installed must be bent with high accuracy, and cannot be easily manufactured.

For this reason, it has been desired to reduce the weight and simplify the manufacture of the heat exchange part of the feed water preheating device and to make the jig common.

JP-A-10-96504

  The problem to be solved by the present invention is that, in a feed water preheating device comprising a heat exchanger configured by connecting fin tubes with 180 ° bend pipes, weight reduction and cost reduction can be achieved by simplification. It is providing the manufacturing method of the feed water preheating apparatus which can aim at commonality.

The invention described in claim 1 is a boiler having a feed water preheating device configured to preheat boiler feed water by a heat exchanger installed in an exhaust gas passage through which exhaust gas discharged from the boiler passes. In a water supply preheating device in which a large number of fin tubes are installed and the end portions of the fin tubes are connected by U-shaped bend tubes, the fin tubes are supported when the fin tubes are connected by the U-shaped bend tubes. A pair of fin tube jigs provided with a groove in the longitudinal direction at regular intervals, the fin tube is set in the groove of the fin tube jig arranged in parallel, and the fin tube jig of the fin tube A holding plate is placed on the opposite side of the groove so that the fin tube is sandwiched between the fin tube jig and the holding plate. The fin tube sandwiched between the plates is fixed in a predetermined number of stages so that the position of the fin tube is fixed, and then the end of the fin tube is connected with a U-shaped bend tube. The jig is extracted from the fin tube group.

According to a second aspect of the present invention, in the manufacturing method of the water supply preheating device, a rail extending in the longitudinal direction is installed on a surface where the fin tube jig and the pressing plate are stacked, and the fin tube jig is stacked. In this case, the rails are engaged so as to prevent misalignment during stacking.

  By carrying out the present invention, it is possible to reduce the weight and cost by simplifying the feed water preheating device itself, and to simplify and share the jig.

Sectional drawing of the feed water preheating apparatus of one Example of this invention Manufacturing process explanatory drawing 1 of the feed water preheating apparatus of one Example of this invention Manufacturing process explanatory drawing 2 of the feed water preheating apparatus of one Example of this invention Perspective view of heat exchanger part of assembled water supply preheating device Front view of heat exchanger part of assembled water supply preheating device Side view of heat exchanger part of assembled water supply preheater

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a feed water preheating apparatus embodying the present invention, FIGS. 2 and 3 are explanatory diagrams of the manufacturing process of the feed water preheating apparatus of one embodiment of the present invention, and FIG. 4 is a heat exchange of the assembled feed water preheating apparatus. FIG. 5 is a front view of the heat exchanger portion of the assembled water supply preheating device, and FIG. 6 is a side view of the heat exchanger portion of the assembled water supply preheating device.

The combustion exhaust gas generated in the boiler 1 is discharged outside through the exhaust gas passage 2, and a feed water preheating device 7 is provided in the middle of the exhaust gas passage 2, and the exhaust gas is discharged outside after passing through the feed water preheating device 7. . The feed water preheating device 7 has a substantially rectangular parallelepiped shape, and the feed water preheating device 7 is provided with an exhaust gas inlet 8 on the side surface and an exhaust gas outlet 9 on the upper surface. The exhaust gas inlet 8 is provided on a side surface of the feed water preheating device 7 but close to the upper surface, and the exhaust gas enters the upper part of the feed water preheating device.

A partition plate 4 that divides the interior into an exhaust gas inlet 8 side and an exhaust gas outlet 9 side is installed in the feed water preheating device. The partition plate 4 is connected to the wall surface of the exhaust gas flow path of the feed water preheating device at the upper end side and the left and right ends, and has a space between the bottom surface of the feed water preheating device at the lower end side. It is divided other than below 4. The interior of the feed water preheating device is divided into two exhaust gas flow paths by a partition plate, the flow path on the exhaust gas inlet 8 side is the exhaust gas flow down flow path 10, and the flow path on the exhaust gas outlet 9 side is the exhaust gas flow up flow path 11. Become. The exhaust gas flow descends in the exhaust gas flow descending flow path 10, turns below the partition plate 4, and then rises in the exhaust gas flow ascending flow path 11.

A heat exchanger composed of a large number of fin tubes 3 extending in the horizontal direction is installed in the exhaust gas flow down flow path 10. The fin tube 3 is provided with heat absorption fins around the entire circumference of the raw tube surface. Since the heat transfer area is increased by installing the heat absorption fins, the heat absorption amount can be increased. Each fin tube 3 in the feed water preheating device 7 is configured to form a long feed water passage that snakes by connecting the end portions, and the feed water into the feed water preheating device is supplied to the fins at the bottom of the fin tube group. Perform from tube 3. The water supply in the water supply preheating device sequentially passes from the lowermost fin tube 3 and reaches the uppermost fin tube 3 while being heated. The pre-heated feed water is taken out from the feed water pre-heating device and supplied into the boiler 1. In the fin tube 3 having a large heat transfer area, the combustion exhaust gas absorbs heat when flowing along the surface of the heat absorption fin. A heat exchanger using the fin tube 3 is installed in the exhaust gas flow down flow path 10, and boiler feed water having a low temperature flows in the fin tube 3, so the exhaust gas that was initially at high temperature heats the fin tube 3. As the time goes on, the temperature will drop. Instead, the water supply flowing through the fin tube 3 increases the temperature.

When assembling the heat exchanger using the fin tube 3, if the heat exchanger has a vertically long shape, that is, if the number of stages of the fin tube 3 is larger than the number of rows, the heat exchanger is assembled by being rotated 90 ° and lying down. . The heat exchanger in FIG. 1 is provided with three rows and six stages of fin tubes 3 and has a vertically long shape. Therefore, the heat exchanger is assembled in a state of lying down sideways.

In manufacture of the heat exchanger by the fin tube 3, the jig | tool 12 for fin tubes for arrange | positioning the fin tube 3 at equal intervals is used. The fin tube jig 12 is a pair of support fittings in which a V-shaped or semicircular groove for supporting the fin tube 3 is dug, and the grooves are arranged at regular intervals in the longitudinal direction. . Two fin tube jigs 12 are placed in parallel at a position corresponding to the length of the fin tube 3 to be used, and the groove of the fin tube jig faces upward. set. At this time, since the distance between the two fin tube jigs 12 is adjusted in accordance with the length of the fin tube 3, it is possible to cope with the difference in fin tube length depending on the model. In addition, the number of fin tubes 3 of the heat exchanger can be adjusted by adjusting the number of fin tubes set in the jig.

When the necessary number of fin tubes 3 are arranged in the groove of the fin tube jig 12, the holding plate 13 is set next. The holding plate 13 is also a pair of two supporting tools for supporting the fin tube 3, but unlike the fin tube jig 12, the groove for placing the fin tube 3 is not dug, and the upper and lower surfaces are Is flat. Further, a rail extending in the longitudinal direction may be provided in a portion where the pressing plate 13 and the fin tube jig 12 overlap, and both may be engaged with each other by the rail. In the figure, a convex rail is installed on the upper surface of the holding plate 13, and a concave rail is installed on the lower surface of the fin tube jig 12 so that they are engaged with each other. By installing rails, it is possible to eliminate deviations during assembly. However, the pressing plate 13 needs to be able to be pulled out by sliding in the horizontal direction, and for this purpose, the rail is assumed to extend in the vertical direction.

The two pressing plates 13 are placed on the upper side of the fin tube end so as to overlap the fin tube jig 12, and the second-stage fin tube jig 12 is placed thereon. The fin tube 3 is set on the second-stage fin tube jig 12 in the same manner as the first stage, and the second-stage pressing plate 13 is placed thereon. The steps of the fin tube 3 and the jig are repeated for the number of fin tubes in the heat exchanger. Although the number of rows of fin tubes in the heat exchanger may differ depending on the model, it is possible to cope with various types of heat exchangers by adjusting the number of stages where the fin tubes 3 are installed. In the embodiment, since the fin tubes 3 are arranged in three rows, they are stacked in three stages. And in the state which piled up the required number of steps, it clamps up and down using a clamp etc., and the position of the fin tube 3 is fixed.

Next, the end portions of the fin tube 3 are connected by the U-shaped bend pipe 6. When welding, if it is easier to work with the fin tube end on top, the fin tube jig may be rotated 90 ° so that the fin tube end on the welding side is on the upper side. . Since the fin tube jig 12 is fastened and fixed in the vertical direction, the pitch of the fin tubes 3 is fixed even when rotated.

Thereafter, the U-shaped bend pipe 6 is sequentially welded to the end portion of the fin tube. When the welding of the U-shaped bend pipe 6 is completed on one surface, the fin pipe jig is further rotated by 180 ° to weld the U-shaped bend pipe 6 at the end of the fin tube on the opposite side.

After the end of welding, the clamp is removed and the pressing plate 13 is removed. Since the pressing plate 13 has flat upper and lower surfaces, it can be pulled out by sliding in the horizontal direction. By removing the pressing plate 13, the fin tube jig 12 can be shifted, and by removing the fin tube jig 12, only the heat exchanger portion remains.

Since the completed heat exchanger does not include the tube plate and the housing, the product can be reduced in weight and is simple and low-cost. Further, the number of fin tubes to be set in one fin tube jig 12 is adjusted according to the number of fin tube stages of the heat exchanger by adjusting the interval between the fin tube jigs 12 installed in parallel according to the length of the fin tube. Since the number of stacked stages of the fin tube jig 12 can be adjusted according to the number of fin tube rows of the heat exchanger, the jig can be shared.

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1 boiler
2 Exhaust gas passage
3 Fin tube
4 Partition plate 5 Heat absorption fin
6 U-bend pipe 7 Water supply preheater 8 Exhaust gas inlet 9 Exhaust gas outlet
10 Exhaust gas flow down flow path 11 Exhaust gas flow up flow path 12 Fin pipe jig 13 Holding plate

Claims (2)

It is a boiler having a feed water preheating device that preheats boiler feed water by a heat exchanger installed in an exhaust gas passage through which exhaust gas discharged from the boiler passes, and the heat exchanger has a large number of fin tubes, In the water supply preheating device in which the ends of the fin tubes are connected to each other with a U-shaped bend pipe, when the fin tubes are connected with the U-shaped bend pipe, grooves for supporting the fin tubes are spaced at regular intervals in the longitudinal direction. The fin tube is set in the groove of the fin tube jig arranged in parallel using the two pairs of fin tube jigs provided in Step 1, and the holding plate is disposed on the opposite side of the fin tube from the fin tube jig. The fin tube is sandwiched between the fin tube jig and the holding plate, and the fin tube is sandwiched between the fin tube jig and the holding plate. The tube is fixed in a predetermined number of stages to fix the position of the fin tube, and then the end of the fin tube is connected with a U-shaped bend tube. After the fin tube is connected, the holding plate and the fin tube jig are connected to the fin. A method for manufacturing a water supply preheating device, wherein the water supply preheating device is extracted from a tube group. In the manufacturing method of the feed water preheating apparatus of Claim 1, the rail extended in a longitudinal direction is installed in the surface which laminates | stacks the said jig | tool for fin pipes, and a pressing plate, and a rail is used when stacking | stacking a fin pipe jig. A manufacturing method of a feed water preheating device, wherein shifting is prevented by meshing.

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