JP3425233B2 - Polishing device and tube expansion device for heat exchanger - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used for repairing heat exchangers.
Polishing apparatus and tube expanding apparatus, for example , polishing apparatus and tube expanding apparatus used for repairing multi-tube heat exchangers used in thermal power plants, nuclear power plants, chemical plants, etc. Corrosion cracking (Stress C
The present invention relates to a heating tube which can be effectively protected when it is damaged by orrosion cracking (hereinafter referred to as SCC).

[0002]

2. Description of the Related Art Among multi-tube heat exchangers used in nuclear power plants and the like, a conventional technique will be described by taking a high pressure feed water heater as an example. As the heating pipe of this high-pressure feed water heater, a γ-type stainless steel pipe or inconel pipe that is unlikely to cause rust is used, which prevents accumulation of impurities such as clad in the cycle system of the plant. Conventionally, as shown in FIG. 16, the end portion of the heating tube 1 is fixed to the tube sheet 2 and the butter ring welding portion 3.

However, when a γ-type tube is used as the heating tube, a slight change in the amount of dissolved oxygen in the water supply system,
Also, there is a problem that SCC microcracks are likely to occur due to a slight mixture of Cl ^{− and} the like. When such a crack is generated and damaged, conventionally, as shown in FIG. 16, a stopper 4 is fitted to the inlet / outlet portion of the end portion of the heating tube 1 on the tube plate side and welded at the weld portion 5. ing. As a result, the damaged heating tube 1 cannot be used.

Such a method does not cause a big problem when the number of damaged and closed heating tubes 1 is small. However, when the number of the heating pipes 1 provided with the stoppers 4 increases, the heat efficiency of the heat exchanger deteriorates, and as a result, the efficiency of the entire plant decreases, and in the worst case, the heat exchanger It is also conceivable that the If this heat exchanger or only the bundle of heating tubes is replaced, the heat exchanger used in the nuclear power plant will have a problem of a significant increase in radioactive waste, or a huge amount of replacement work. There were problems of cost and construction period.

From such a point of view, conventionally, the heating pipe 1 which has been damaged is not provided with the closing plug 4 as shown in FIG.
As shown in (b), a short tubular protective sleeve 6 made of a metal piece is fixed to the inner peripheral side of the heating tube 1 at the damaged portion by a brazing layer 6a. Instead of this brazing, it may be welded by a YAG laser. Thereby, a method of locally repairing the damaged heating pipe 1 without closing it is adopted.

[0006]

However, when the protective sleeve 6 is brazed by the brazing method, the protective sleeve 6 is exposed to the sensitizing temperature range of the γ-system heating pipe material for a long time during the brazing. When the heating pipe is damaged by SCC, the SCC damage of the heating pipe is promoted, which may cause an unnecessary problem.

Further, when the protective sleeve 6 is fixed by YAG laser welding or the like, it is difficult to select welding conditions, and when performing horizontal welding on a vertical heat exchanger such as a steam generator. , Not a big problem. However, when the protective sleeve 6 is welded to the heating tube of the horizontal heat exchanger in all positions, not only the welding conditions but also
It was also necessary to specify the working conditions in the surrounding area. Furthermore, the welding torch itself becomes long in order to weld a part far from the tube sheet surface. Therefore, when the heat exchanger is a relatively large heat exchanger such as a steam generator, the water chamber has a large space, and there is a margin in workability, there is no problem. However, in a normal heat exchanger, it was substantially impossible to perform YAG laser welding in the water chamber while the water chamber was still installed. In addition, working for a long time in a narrow water chamber of the heat exchanger has a problem of increasing radiation exposure.

The object of the present invention was made in view of the above-mentioned circumstances, and is effective when a heating pipe of a heat exchanger is damaged by stress corrosion cracking (SCC) or the like. Of the heat exchanger, which can be protected against damage, can be repaired very easily and efficiently, and can be repaired accurately and accurately.
And to provide a tube expanding device.

[0009]

Means for Solving the Problems] To achieve this object, a polishing apparatus according to claim 1 of the present invention is a polishing apparatus for polishing an inner surface of the heat pipe that is supported by the tube plate of the heat exchanger The rotary shaft is inserted into the heating pipe and is rotated by a drive source, and is fixed at or near the end of the rotary shaft, and is rotated by the rotary shaft to polish the inner surface of the heating pipe. Polishing wheel, a rotary sleeve rotatably fitted to the rotary shaft and provided with an air passage to which compressed air is supplied, and a heating sleeve that receives compressed air from the air passage to expand its diameter. is pressed in the inner surface, thereby preventing vibration of the rotary shaft, are characterized by having a a prevention portion shake provided on said rotary sleeve
It

Further, the pipe expanding device according to claim 2 is a pipe expanding device for inserting a protective sleeve into a heating pipe supported by a tube plate of a heat exchanger and radially expanding the protective sleeve. Has a jaw that engages with the end of the protective sleeve, the spindle inserting the protective sleeve into the heating tube while engaging the protective sleeve with the jaw , and the spindle formed in the spindle. A pressure medium flow passage for circulating the medium and a pressure medium flow passage are mounted outside the spindle in communication with the pressure medium flow passage, and are expanded radially outward by the pressure medium flowing from the pressure medium flow passage to form a protective sleeve. And an expander that expands in the direction.

[0011]

According to the first aspect of the present invention , the rotary shaft inserted inside the heating tube rotates the polishing wheel, and the inside of the heating tube is polished. At this time, the shake preventing device is pressed against the inner surface of the heating tube to prevent the shake of the rotating shaft. Therefore, the polishing work inside the heating tube is stably performed. By this polishing, the protective sleeve is fixed to the heating tube accurately and with good contact accuracy. Therefore, there is no melting loss in welding, and welding defects do not occur.

Further, according to a second aspect, the spindle joint is
The protective sleeve is inserted into the heating tube while the end of the protective sleeve is engaged with the heating sleeve. The pressure medium is caused to flow from the pressure medium flow path of the spindle to the expander, the expander is expanded radially outward, and the protective sleeve is expanded radially. As a result, the protective sleeve is fixed to the heating tube accurately and with good contact accuracy. Therefore, there is no melting loss in welding, and welding defects do not occur.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A polishing device and a pipe expanding device used for repairing a multi-tube heat exchanger according to an embodiment of the present invention will be described below with reference to the drawings.

In the heat exchanger to be repaired in this embodiment, as shown in FIG. 1, the heating tube 1 is fixed to the ends of the tube sheet 2 and the butter ring welded portion 3. Heating tube 1
Further, it is supported by the support plate 7. A water chamber 10 is provided adjacent to the tube sheet 2 and the butter ring welded portion 3. The water chamber 10 is provided with an inlet 8 for introducing a medium into the heating pipe 1 and an outlet 9 for a medium discharged from the heating pipe 1. Further, the water chamber 10 is covered with an end plate 11.

In the repair according to this embodiment , roughly, the end plate 11 of the water chamber 10 is cut, the inner peripheral side of the heating tube 1 is polished, and the protective sleeve 6 is inserted inside the heating tube 1. The protective sleeve 6 is expanded from the inside, both ends of the protective sleeve 6 are welded to the heating tube 1, and finally repaired as shown in FIG. After that, the cut end plate 1
1 is restored to the water chamber 10.

Specifically, first, in order to secure a working space for mounting the protective sleeve 6, as shown in FIG. 3, the end plate 11 side of the water chamber 10 of the heat exchanger is cut. That is, the ring-shaped rail 13 for traveling the cutting self-propelled carriage 12 is attached. The cutting self-propelled carriage 12 is equipped with an oxygen-acetylene gas burner or a plasma cutting torch 14. The cutting self-propelled carriage 12 cuts the entire circumference of the end plate 11 while leaving one point above the end plate 11 while rotating on the ring-shaped rail 13. The reason for leaving one point on the upper side is to prevent the end plate 11 from coming off during work. In this cutting self-propelled trolley 12, Z indicated by an arrow 15 in FIG. 3 is provided so that the distance between the cutting torch 14 and the cutting surface is always kept constant.
The distance in the axial direction is taught by a contact type sensor (not shown) and feedback-controlled. Similarly, FIG.
Is also controlled in the axial direction indicated by the arrow 16 in FIG. When the cutting self-propelled carriage 12 makes one rotation and the end plate 11 is cut, the end plate 11 is removed, and the work of attaching the protective sleeve 6 is performed.

Before the protection sleeve 6 is attached, the sleeve or the like is attached to the inner surface of the heating tube 1, and it is difficult to weld the protection sleeve 6 in the state as it is. Therefore, before this attachment, as shown in FIGS. 4 and 5, the polishing device 19 performs the polishing operation. This polishing device 1
A rotary shaft 22 (see FIG. 5) is provided on the rotary shaft 9. The polishing wheel 21 is fixed to the rotary shaft 22 by a nut 24, and a rotary sleeve 26 is fitted on the rotary shaft 22. An O-ring 25 is provided between the rotary shaft 22 and the rotary sleeve 26. Further, the rotary sleeve 26 is provided with an air passage 23 for supplying compressed air, and a shake preventing portion 20 is provided which receives the compressed air from the air passage 23 to expand its diameter and press against the inner surface of the heating tube 1. Has been. By pressing the shake preventing portion 20 against the heating pipe 1, the shake of the rotating shaft 22 is prevented, and the inner surface of the heating pipe 1 is prevented from being damaged. The shake prevention unit 20 is provided at two or more places in one polishing apparatus, and the shake prevention unit 20 needs to have a width of 10 mm or more and be expandable by 2 mm or more in diameter. With this polishing device, the rotary shaft 22 is rotated, the polishing wheel 21 is rotated, and the inner surface of the heating tube 1 is polished. By this polishing, the protective sleeve 6 is fixed to the heating tube 1 accurately and with good adhesion accuracy. Therefore, there is no melting loss in welding, and welding defects do not occur.

Next, as shown in FIGS. 6 and 7, the protective sleeve 6 is inserted into the heating tube 1, and the protective sleeve 6 is inserted.
Is pressed against the inner surface of the heating tube 1 by the hydraulic expander 30 (tube expanding device). As shown in FIGS. 6 and 7, a spindle 31 is provided in the hydraulic expander 30, and a pressure medium flow passage 32 is provided inside the spindle 31.
Are formed. Further, the spindle 31 is provided with a plurality of expanded pipe portions 33, and the expanded pipe portion 33 is provided with a pressure medium region 34 communicating with the pressure medium flow passage 32.
On the outer peripheral side of the pressure medium region 34, the cylindrical pressure rubber 3
5 (expander) is provided. This expanded section 3
3, the protective sleeve 6 is inserted when the protective sleeve 6 is inserted.
A jaw 36 for pressing is provided.

This hydraulic expander 30 (tube expanding device)
Thus, the protective sleeve 6 is expanded in the radial direction and expanded, but in order to prevent the expansion of microcracks on the outer surface of the tube, the expansion is performed at the tube plate 2 and the support plate 7.
The degree of pipe expansion is such that the expansion ratio of the protective sleeve 6 is 3% or less. By this tube expansion, the protective sleeve 6 is fixed to the heating tube 1 accurately and with good contact accuracy. Therefore, there is no melting loss in welding, and welding defects do not occur. Also, when inserting the protective sleeve 6,
The end of the protective sleeve 6 is engaged with the jaw 36, the spindle 31 is inserted to a predetermined position, and the expander work is performed.

Next, as shown in FIGS. 8 and 9, the tip of the protective sleeve 6 is welded to the heating tube 1 using the YAG laser system 40 capable of transmitting over a relatively long distance.
The YAG laser system 40 includes a laser oscillator 41
A laser oscillator power supply 42 and a laser oscillator cooling unit 43 are connected to the laser oscillator 41, and a remote controller 44 extends from the laser oscillator 41. A YAG laser torch device 45 is attached to the heating tube 1 and the protective sleeve 6 side, and is connected to the laser oscillator 41 via an optical fiber 46. Furthermore, this YAG laser torch device 45
The gear 47 is provided with a gear 47 and a gear 48 meshing with the gear 47, and the gear 48 is driven by a motor 49.
As a result, when the motor 49 is driven, both gears 47,
48 is rotated and the YAG laser torch device 45 is rotated. Further, the torch device 45 is prevented from rotating by the stopper 51. This YAG laser torch device 45
The output optical system 52 is provided in the.

With this configuration, the laser oscillator 41, the laser oscillator power supply 42, and the laser oscillator cooling unit 43 are connected to each other during welding work at a nuclear power plant or the like.
The remote controller 44 and the YAG laser torch device 4 are installed in an appropriate place in the building where the radiation exposure is small.
Only 5 is carried into the water chamber 10. The size (M) from the tube sheet 2 to the welding position is adjusted by the torch stopper 51, and the YAG laser torch device 45 is inserted into the heating tube 1 until the torch stopper 51 contacts the outer surface of the tube sheet 2. When the torch device 45 reaches a fixed position,
The laser beam is rotated by the motor 49 and the gears 47 and 48 at the same time as the laser irradiation, and the welding bead 53 of the first pass is formed by the one-pass welding.

Next, considering the case where the welding bead 53 of the first pass does not completely weld the protective sleeve 6 and the heating tube 1, as shown in FIG. 9, the welding position is slightly shifted,
The second pass welding 54 is performed. In this case, 1.0 to 2.0 mm between the torch stopper 51 and the tube sheet 2.
The spacer is sandwiched, and the torch device 45 is pulled out by the thickness of this spacer, whereby the positions of the welding beat 53 of the first pass and the welding beat 54 of the second pass are adjusted. The position is shifted.

Next, when the welding of the tip portion of the protective sleeve 6 is completed, as shown in FIGS.
A mold GTAW torch device 60 is used and the protective sleeve 6 is fillet welded to the heating tube 1 on the tube sheet 2 side. In addition,
IBW is an abbreviation for InternalBoreWelding, and GTAW is GasTungstenArc.
Abbreviation for Welding. This IBW GTAW torch device 60 has a welding power source 61, a welding control device 62, an arc monitor 63, as shown in the system diagram of FIG.
And a welding torch 64. Furthermore, FIG.
As shown in FIG. 1, a torch electrode 66 is provided at the tip of the welding torch 64.

In the case of this GTAW torch welding, the welding position is measured in advance by a depth gauge, and the torch insertion length is controlled by fitting the ring-shaped shim member 65 corresponding to this measured value. As the welding position, as shown in FIG. 10, the end of the protective sleeve 6 closer to the tube sheet 2 is separated from the end surface of the tube sheet 2 by L (L = 10D, D is the tube inner diameter) or more. Are preferably welded together. As a result, it is possible to prevent the occurrence of turbulence at the inlet of the heating pipe 1.

In the welding sequence at this time, as shown in FIG. 14, first, the torch shield gas is flown (see FIG. 1).
4, reference numeral 71), an arc is generated at a break flow time of 3 to 5 minutes (reference numeral 72, reference numeral 72), and 10
The welding current (FIG. 14, reference numeral 75) is reached after a slope up time (FIG. 14, reference numeral 73) after ˜20 seconds. A pulse current (pulse base current 77, pulse piece current 78) is adopted as the welding current in order to enhance the stirring effect of the molten pool. At this point, the welding torch 64 is rotated. When the welding torch 64 makes one rotation, the welding current (75) reaches the slowdown (76) and the crater processing current (82), at which point the rotation of the welding torch 64 is stopped and the crater processing is performed.
The torch shield gas (71) is also stopped 5 to 10 seconds after the arc is completely stopped (81). These sequences are completely controlled by the control device 62 in advance, but the arc generating part cannot be visually observed. Therefore, as shown in FIG. 12, paying attention to the fact that there is a correlation between the arc length (83) and the arc voltage (E),
By monitoring the arc voltage (E), the tungsten torch electrode 66 is monitored for damage and burn-through. That is, as shown in FIG. 12, the arc length (83)
Is changed to (l1-l2), the arc voltage (E) changes to (E1-E2) as indicated by reference numeral 86. Reference numeral 85 indicates a welding power source external characteristic curve. Therefore, by maintaining the arc voltage (E) at an appropriate value (for example, 12 to 14 V) by the arc monitor 63, the arc length (83) is properly maintained.

Next, when the welding of the protective sleeve 6 to the heating pipe 1 is completed, the end plate 11 is restored and welded to the water chamber 10.
In this case, the ultra-large diameter thick-walled pipe needs to be orbitally welded, and manual welding requires a lot of time and has a problem in quality. Therefore, in the present embodiment, as shown in FIG. 15, a welding carriage 91 controlled off line by welding conditions created by the IC card creation system 99.
However, the orbital welding is performed by being rotated around the water chamber 10.

As the welding method in this case, the MAG and MIG welding methods are adopted in consideration of work efficiency. This welding system is provided with a welding power source 93, an IC card type welding control device 94, a data processing device 100, a welding traveling carriage 91, a remote control box 96, and a traveling carriage rail 92.

Welding carriage 9 equipped with welding torch 97
Welding is performed by weaving the welding torch 97 while 1 travels from the lower part to the upper part of the water chamber 10. Further, the welding groove at the time of recovery welding is grinder-finished because machining is difficult. Therefore, the dimensional accuracy is not always sufficient. Therefore, the welding traveling carriage 91 is equipped with the groove copying teaching probe 98, and welding is performed in accordance with the groove even if the groove precision is poor.

The present invention is not limited to the above-mentioned embodiments, and can be variously modified. In particular,
The means for cutting the end plate, the means for polishing the inner surface of the heating tube, the means for expanding the protective sleeve, the means for welding the protective sleeve, and the means for restoring the cut end plate are optional and can be freely selected, and shown in the examples. It is not limited to what you eat.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multi-tube heat exchanger for repair .

FIG. 2 is an enlarged sectional view of a portion A in FIG.

FIG. 3 is an enlarged cross-sectional view of the water chamber and the end plate of the heat exchanger shown in FIG.

4 is a cross-sectional view of a state in which a polishing device is inserted in the heating pipe of the heat exchanger shown in FIG.

5 is an enlarged cross-sectional view of the polishing apparatus of FIG.

FIG. 6 is a cross-sectional view showing a state in which the tube expanding device is inserted into the heating tube of the heat exchanger shown in FIG.

7 is an enlarged sectional view of the tube expanding device of FIG.

8 is a cross-sectional view showing a state in which a YAG laser welding system is inserted in the heating pipe of the heat exchanger shown in FIG.

9 is an enlarged cross-sectional view of the laser welding system of FIG.

10 is a cross-sectional view showing a state in which an IBW GTAW torch welding device is inserted into the heating pipe of the heat exchanger shown in FIG.

11 is an enlarged cross-sectional view of the IBW GTAW torch welding device of FIG.

FIG. 12 is a schematic diagram showing a relationship between an arc current and an arc voltage, and an arc length.

13 is a schematic configuration diagram of the IBW GTAW torch welding apparatus of FIG.

14 is an operation sequence diagram of the IBW GTAW torch welding apparatus of FIG.

FIG. 15 is a schematic configuration diagram of an automatic orbital MAG welding apparatus for an end plate and a water chamber.

FIG. 16 is a cross-sectional view of a heating tube and a tube sheet portion showing a conventional repairing method .

17A is a cross-sectional view of a heating tube and a tube sheet showing another conventional repairing method , and FIG.
The expanded sectional view of the B section of (a).

[Explanation of symbols]

1 heating tube 2 tube sheet 6 Protective sleeve 10 water chamber 11 End plate 19 Polishing equipment 20 Shake prevention unit 21 Polishing Wheel 22 rotation axis 30 Tube expander (hydraulic expander) 31 spindle 32 Pressure medium flow path 35 Expander (Pressurized rubber 35)

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F28F 11/02 B24B 5/40

Claims (2)

(57) [Claims] 1. A polishing device for polishing an inner surface of a heating tube supported by a tube plate of a heat exchanger, comprising: a rotating shaft inserted into the heating tube and rotated by a drive source. A polishing wheel that is fixed to the end of the rotary shaft or in the vicinity thereof and that is rotated by the rotary shaft to polish the inner surface of the heating tube, and is rotatably fitted to the rotary shaft and supplied with compressed air. A rotary sleeve provided with an air passage, and a rotary sleeve that receives compressed air from the air passage, expands its diameter, and is pressed against the inner surface of the heating pipe, thereby preventing the rotation shaft from swinging. A shake prevention part,
A polishing apparatus comprising: 2. A heating tube supported by a tube plate of a heat exchanger,
Insert the protective sleeve, a pipe expanding device for expanding the protective sleeve in the radial direction, has a jaw for engaging the end of the protective sleeve, the job
While engaging the protective sleeve over the spindle for inserting the protective sleeve into the heating tube, is formed in the spindle, the pressure medium flow path for flowing pressure medium, the pressure medium flow path to the outside of the spindle It is installed in communication,
An expander, comprising: an expander that is expanded radially outward by a pressure medium flown from a pressure medium flow path to expand the protective sleeve in the radial direction.