EP0815389A1

EP0815389A1 - Device and process for treating or inspecting a pipe floor in a steam generator

Info

Publication number: EP0815389A1
Application number: EP96905725A
Authority: EP
Inventors: Rainer Kunz; Herbert Schramm
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1995-03-15
Filing date: 1996-03-13
Publication date: 1998-01-07
Also published as: JPH11501720A; WO1996028692A1

Abstract

A device for treating or inspecting the pipe floor (6) in a steam generator (2) comprises according to the invention a flexible lance (50) with a flexible strip (52) carrying at least one flexible supply line (58, 66, 72) for a treatment or inspection head (63, 68, 70) at one free end (53) of the lance (50); and a transport device (20) which can be introduced into a pipeway (6) in the steam generator (2). The transport device (20) is provided with a forward feed device (40) for forward feeding, deflecting and aligning the flexible strip (52) at an angle (α1; α2) to a longitudinal axis (26) of the transport device (20). The forward feed device contains rollers (41, 42, 43, 44) between which the strip (52) is guided and at least one of which can be driven in order to feed the strip (52).

Description

description

Device and method for processing or inspecting a tube sheet of a steam generator

The invention relates to a device and a method for processing or inspecting a tube sheet of a steam generator.

Endoscopic inspections of the tube sheets of steam generators show that in areas which are poorly flowed through by the water of the secondary circuit, adhering contaminants remain, the height of which in some places can be a few centimeters.

Because of the geometric shape of their distribution on the tube sheet, these deposits are referred to as deposit kidneys. They arise because loose deposits remain in the poorly flowed inside area of the heating tube bundle, while in the better flowed outside area they are entrained by the flow of the feed water flow on the secondary side. With increasing operating time, these deposits adhere more and more firmly to the tube sheet. Through further accumulation processes, in the course of several operating cycles, deposit conglomerates with an increased metal and salt quantity concentration in relation to loose impurities increase in an extent of several centimeters.

Analyzes of these solid conglomerates of deposits show a mixed structure that consists essentially of magnetite. In addition to further oxidation levels of iron, there are also increased salt concentrations, especially sulfates, silicates and phosphates. Likewise, increased chromium and nickel contents can result from the storage of metal chips. The mechanical hardness can in some places be the hardness of the

Exceed heating tube material, so that in a spatial Limiting growth there is a risk of damage to the heating pipes (denting).

For this reason, in the case of tube sheets of steam generators, it must be checked regularly on the secondary side whether and to what extent deposits have formed between the heating tubes. These deposits must then be removed in order to avoid damage to the heating pipes.

For the adherent deposits, this is primarily done by spraying. The gaps between the heating pipes are difficult to reach due to the small pipe spacing, which is usually around 8 - 11mm with a square arrangement of the heating pipes and which can be between 3 and 4mm in narrower triangular arrangements. Spraying methods are therefore primarily used, as are known, for example, from European Patent 0 084 867. In these spraying processes, a high-pressure water jet is sprayed from a nozzle in the pipe lane into the spaces between the heating pipes.

However, it has been shown that deposits adhering to the interior of the tube bundle can only be removed incompletely. To ensure efficient cleaning of the tube sheet, it is therefore necessary to guide a spray head directly into the gaps between the heating tubes and to direct a high-pressure liquid jet directly onto the deposits inside the heating tube bundle.

A device suitable for this is known, for example, from European Patent 0 305 483. In the device disclosed there, a flexible spray lance is provided, which has a spray head with a plurality of nozzles at its free end, from which the spray liquid emerges. The flexible spray lance is constructed from a flexible band in which channels with a circular cross cut. Metallic capillaries are inserted into these channels, through which the spray liquid is led to the spray head. The band and the channels are made in one piece by extrusion from a plastic.

The belt is mounted in a rigid guide with a curved end, with which it can be deflected by a predetermined angle. The rigid guide is mounted in a transport device which can be introduced into the tube passage of the steam generator and can be moved along this tube passage. To drive the belt, several jointly driven gear wheels are provided, the teeth of which engage in corresponding perforations of the belt. The curved end of the rigid guide aligns the free end of the spray lance with the pipe gaps.

However, by using a plastic with capillaries embedded in the longitudinal direction, the stability with a large free arm length is restricted.

From US-A-5, 036, 871 a device for cleaning the tube sheet is known, in which instead of a spray lance constructed from a one-piece flexible band, a flexible band composed of a plurality of interconnected individual members is provided through which a high pressure hose is passed. In order to increase its stability, additional cables can be inserted into this band.

Such a segmented band is also used in the devices for inspecting and processing the tube sheet known from US Pat. No. 5,065,703 and US Pat. No. 5,286, 154, in which inspection optics and mechanical processing tools, for example drills or Gripping tools are used. In order to be able to accommodate high-pressure injection capillaries, the segments connected to one another are so wide, however, that very narrow pipe gaps, as they are in triangular division heating tube bundles, can no longer be used.

From US-A-4,407,236 a flexible spray lance is known, which is constructed from a band made of spring steel, on which one or more capillaries for the spray liquid are attached on one side. The capillaries are wave-shaped and open downwards at the free end of the band into a semicircular recess on the underside of the band, so that the spray liquid emerging from them is directed downwards onto the tube sheet. The narrow sides of the belt are guided in grooves in an upper and a lower plate, which are introduced into the tube lane of the steam generator. The groove in the lower plate deflects the belt onto a pipe gap. The belt is driven by a pushing force exerted on the belt from behind. This requires a high bending stiffness of the band and is also only possible with steam generators in which a hand hole is arranged at the same height as the pipe lane.

The invention is based on the object of specifying a device for processing and inspecting the tube sheet of a steam generator, which is of simple construction and can also be used in steam generators in which the hand hole is not arranged at the height of the tube passage, and which also for the Machining and inspection of narrow pipe gaps is suitable. In addition, the invention is based on the object of specifying a method for processing and inspecting the tube sheet of a steam generator.

The first-mentioned object is achieved with a device having the features of claim 1. The device for processing or inspecting a tube sheet of a steam generator contains according to the invention a) a flexible lance with a flexible band, in which at least one flexible supply line for a processing or inspection head arranged at a free end of the lance is arranged, b) a transport device for the flexible lance that can be inserted into a pipe lane of the steam generator , c) a feed device arranged on the transport device for feeding, deflecting and aligning the flexible belt at an angle to a longitudinal axis of the transport device, d) rollers being provided in the feed unit for feeding, deflecting and aligning the belt are between which the tape is guided and of which at least one roller can be driven to advance the tape.

In a further embodiment of the invention, a feed device is provided which is pivotably arranged in the transport device. As a result, the free end of the band can always be placed directly above the tube sheet, even with different free lengths.

In particular, a feed device arranged vertically adjustable to the longitudinal axis of the transport device is provided.

In a further embodiment of the invention, a transport device is provided which contains a striding device for its forward movement, which can be supported laterally on heating pipes arranged at the edge of the pipe lane. This enables the device to be positioned precisely relative to the pipe gaps.

In a further advantageous embodiment of the invention, a band made of steel is provided which has recesses arranged one behind the other in its longitudinal direction and through which the supply line is threaded. This enables a particularly narrow and stable construction. In particular, in each case in the longitudinal direction of the band between the recesses are formed for receiving the supply line, which alternately extend to one and the other side of the band. As a result of this measure, the supply lines do not have to be bent when threading.

In one embodiment, a spray head is provided as the processing head, which is supplied with a spray liquid via a metallic capillary fixed to the belt, preferably a capillary consisting of a nickel-titanium alloy.

In a further embodiment, a spray head is provided with at least two outlet openings for the spray liquid, which are inclined at different angles against a longitudinal axis of the belt. By means of this measure, by adjusting the mass flows to the outlet openings, the resultant of the recoil forces generated by the outflow of the spray liquid can be directed at least approximately parallel to the longitudinal axis of the belt.

In a further embodiment, a recovery tool is provided as the processing head, which can be actuated via a cable pull guided in the band.

In addition, an optical fiber cable for an endoscope arranged at the free end of the lance can be guided in the band.

The second-mentioned object is achieved with a method having the features of patent claim 13. In the method for machining or inspecting a tube sheet of a steam generator according to the invention

a) a transport device is introduced into a pipe lane of the steam generator, the b) carries a flexible lance with a flexible band, in which at least one flexible supply line for a processing or inspection head arranged at a free end of the lance is arranged, and on which

c) a feed device for advancing, deflecting and / or aligning the flexible belt at an angle to a longitudinal axis of the transport device is arranged, whereby

d) the flexible belt is guided between rollers mounted in the feed device, at least one roller of which is driven to feed the belt.

To further explain the invention, reference is made to the exemplary embodiments of the drawing, in which:

1, 2 and 3, a device according to the invention in a working position in the steam generator is illustrated in a top view or in a side view parallel or transverse to a pipe lane. IG 4 shows a further embodiment of a device according to the invention within the steam generator in a side view transverse to the Rohrgasse. IG 5 shows a further advantageous embodiment of the invention in a plan view. IG 6 and 7 show in a side view (flat side) and a top view (narrow side) a flexible band provided as a spray lance and in IG 8 the free end of the spray lance is shown enlarged. IG 9 and 10 show further configurations of the flexible band. IG 11 shows a flexible belt with a gripping tool as the machining head. 1 shows a steam generator 2 in a horizontal partial section at the height of a hand hole 4. A plurality of heating tubes 10, which are arranged parallel to one another, open into a tube plate 6 which is visible in FIG. 1 and into a pipe alley 12 via the hand hole 4 Transport device 20 is introduced, with which a free end 53 of a flexible lance 50 can be introduced, starting from the tube alley 12, into a tube gap 14 running perpendicular to the tube alley 12. In the figure, a steam generator 2 is shown with a triangular arrangement of the heating pipes 10, in which there are particularly narrow pipe gaps.

The flexible lance 50 is constructed from a band 52 on which supply lines 58, 66, 72 for supplying a processing or inspection head 63, 68, 70 arranged at the free end 53 are arranged.

The transport device 20 comprises a slide plate 21 with which it is placed on the tube sheet 6. For moving forward within the tube alley 12, a walking mechanism is provided in the transport device 20, as is known, for example, from the European patent specification 0 084 867. For this purpose, the transport device 20 comprises two support bodies 22 and 24 which can be displaced relative to one another in a longitudinal axis 26 of the transport device by means of a pneumatically actuated piston 28. On each of the support bodies 22 and 24, pneumatically extendable support elements 30 are provided in pairs, each of which is supported on opposite heating pipes 10 on the edge of the pipe lane 12. By alternately locking the support elements 30 and actuating the piston 28, the transport device 20 moves forward in the tube alley 12.

On the transport device 20, a feed device 40 is arranged, which has a motor-driven drive roller 41 and an associated one, which is set against its circumference Contains guide roller 42. The flexible lance 50 is threaded into the drive roller 41 and guide roller 42.

The feed device 40 contains two further guide rollers 43 and 44, which are mounted against one another on their circumference and receive the lance 50 threaded between the drive roller 41 and the guide roller 42 and at an angle α1 to the longitudinal axis 26 and thus to a central axis 14 of the pipe line parallel to it Set 12. In the example of the figure, this angle is 90 °, so that the lance 50 can be moved into the pipe gaps 14.

In the advantageous embodiment shown in the figure, the drive roller 41 and the guide roller 43 are coupled to one another by a circumferential belt 45. In the same way, a belt 47 is also guided around the guide rollers 42 and 44 and a deflection roller 46, which lies in the area of the drive roller 41 on the belt 45. This measure results in a particularly secure guidance of the lance 50.

The deflection angle α1 of the lance 50 is determined by the mutual position of the drive roller 41 and the guide rollers 42, 43 and 44 on the transport device 20.

In a further advantageous embodiment, the feed device 40 can additionally be displaced relative to the transport device 20 parallel to the longitudinal axis 26 or rotated about a vertical axis in order to enable the flexible lance 50 to be precisely aligned with the pipe gaps 14.

FIG. 2 shows how the lance 50 constructed from the band 52 is passed through the hand hole 4 from the outside. Since the band 52 cannot be bent in the plane defined by its flat sides and the tube sheet 6 is located below the lower edge of the hand hole 4, the band 52 must pass through with the horizontally oriented flat side Hand hole 4 guided and rotated within the steam generator 2 by 90 °.

According to FIG. 3, the feed device 40 is arranged in the transport device 20 so as to be pivotable about an axis of rotation 48 running parallel to the longitudinal axis 26. As a result, the free end 53 of the lance 50 can be positioned directly above the tube sheet 6 even with a different extension length 1.

In the advantageous embodiment according to FIG. 4, the feed device 40 is also mounted on a slide 28, which enables the height of the feed device 40 to be adjusted perpendicular to the longitudinal axis 26 and thus parallel to the heating tubes 10.

5 shows an embodiment in which the lance 50 is oriented at an angle α2 = 30 ° relative to the longitudinal axis 26 of the transport device 20, so that those extending at an angle of 30 ° to the central axis 14 of the tube alley 12 also extend Pipe gaps 16 can be traversed by the lance 50. As a result, the dead areas which are poorly detected when driving at an angle α1 = 90 ° can also be achieved. Also in this special embodiment, a feed device 400, which is pivotable in its entirety about an axis 49 running parallel to the tube sheet, is provided. In this exemplary embodiment, too, rollers 410, 420, 430 and 440 are provided for driving, deflecting and aligning the lance 50. In addition, it can be advantageous if the entire feed device 400 is arranged to be displaceable on the transport device 20 or to be pivotable about an axis perpendicular to the longitudinal axis 26, in order to enable precise threading into the pipe gaps 16.

According to FIGS. 6 and 7, a lance 50 contains a flexible metallic material which preferably consists of a chromium-nickel steel

Band 52 with a wall thickness between 0.1 and 0.2 mm, in the equidistant one behind the other parallel to its longitudinal direction Recesses or holes 54 are punched, which form two rows 56a and 56b. A supply line, for example a capillary 58 for a processing head arranged at the free end 53, in the exemplary embodiment a spray head 63, is threaded through these rows 56a and 56b.

The capillaries 58 preferably consist of a memory metal consisting of a nickel-titanium alloy, for example a metal commercially available under the name Nitinol SE 502. Their compressive strength is greater than 1000 bar with an outside diameter between 2 and 3 mm.

The capillaries 58 are guided through the holes 54 alternately from opposite sides of the band 52. Between the holes 54 of a row 56a or 56b, parallel to a longitudinal axis 62 of the band 52, groove-shaped formations or beads 60 with a semicircular cross section are embossed into the band 52, which alternately alternately on one and on the other side of the band 52 are formed. In this way, the formations 60, together with the holes 54 in a row 56a or 56b, form a rectilinear channel into which the capillary 58 can simply be inserted.

Instead of the circular holes shown in FIGS. 6 and 7, recesses in the form of narrow slots transversely to the longitudinal axis 62 can also be provided, through which the capillary 58 can be threaded.

According to FIG. 8, the capillaries 58 assigned to the rows 56a and b are bent away from a longitudinal axis 62 of the band 52 in the plane defined by the flat side of the band 52. At the end of the capillaries 58, nozzles 64 are preferably arranged, in which the emerging spray jet is accelerated and exits from outlet openings 65. In the exemplary embodiment, the outlet openings 65 are arranged perpendicular to the flat side of the band 52, ie the normal or central axes of the outlet openings 65 lie approximately in the plane (band plane) defined by the flat side. The outlet openings 65 are arranged with their normals at an angle βa or βb to the longitudinal axis 62. These angles βa and βb have opposite signs with respect to this longitudinal axis 62. The outlet openings 65 are adapted to the respective mass flow of the spray liquid emerging from them, that is to say adapted to the quantity of spray liquid emerging from them per unit of time, so inclined to the longitudinal axis 62 in the belt plane that the sum or the resultant F of the the band 52 acts approximately parallel to the longitudinal axis 62 of the band 52 by the reaction forces Fa and Fb exerted by the spray liquid. In other words: the reaction forces acting transversely to the longitudinal axis 62 and approximately in the strip plane in the exemplary embodiment of the drawing are compensated. This prevents the band 52 from being pushed away from the tube bottom.

The nozzles 64 are preferably of identical construction, so that a symmetrical arrangement (ßa = -ßb) of the nozzles 64 in the belt plane compensates for the transverse forces when the mass flows through the two nozzles 64 are identical. Such a symmetrical arrangement is particularly necessary in the case of a structurally identical design of the nozzles 64 if instead of the two capillaries 58 provided in the exemplary embodiment only one capillary is provided, from which two paths are only branched off directly in front of the spray head 63.

In the case of an asymmetrical arrangement of the nozzles, the mass flows must be adjusted accordingly until the transverse forces are compensated. This can be done by a fixed setting or by controlling the mass flows distributed over the capillaries 58.

Likewise, instead of two nozzles 64 or outlet openings 65, a plurality of outlet openings can also be provided, in this case too, the orientation of the outlet openings and the respective mass flows must be coordinated with one another in such a way that compensation of the transverse forces occurs.

The nozzles 64 or outlet openings 65 can also be arranged with their normal or central axis obliquely to the flat side of the band 52. In this case too, the angles and the respective mass flows can be coordinated or controlled in such a way that the force components occurring transversely to the flat side of the band 52 are compensated for in this case, so that a lateral deflection of the band 52 is avoided.

According to FIG. 9, an optical fiber cable 66 of an endoscope 68 is inserted into the channel 56b, with which the spraying process can be observed.

In a further embodiment of the invention, FIG. 10 shows a band with three channels 56a, b, c, the two channels

56a, b are each provided with capillaries 58 for spraying and a channel 56c contains an optical fiber cable 66 of an endoscope 68.

According to FIG. 11, a gripping tool 70, for example, is arranged at the free end 53 of the lance 50 as a rescue tool. In this case, instead of capillaries, traction cables 72 are guided as supply lines through the holes 54, with which torque can be exerted on pivotably mounted pliers 74 and 76.

Claims

claims

1. Device for processing or inspecting a tube bottom (6) of a steam generator (2), with a) a flexible lance (50) with a flexible band (52), in which at least one flexible supply line (58, 66, 72) is arranged for a processing or inspection head (63, 68, 70) arranged at a free end (53) of the lance (50), b) one which can be inserted into a pipe lane (6) of the steam generator (2) Transport device (20) for the flexible lance (50), c) a feed device (40, 400) arranged on the transport device (20) for advancing, deflecting and aligning the flexible belt (52) to an angle (α1; α2) to a longitudinal axis (26) of the transport device (20), where d) rollers (41, 42, 43, 44) are provided in the feed device (40; 400) for advancing, deflecting and aligning the belt (52), between which the band (52) is guided and of which at least one roller (41, 42, 43, 44; 410, 420, 430, 440) can be driven to advance the belt (52).

2. Device according to claim 1, with a pivotable in the transport device (20) arranged feed device (40, 400).

3. Device according to one of the preceding claims, with a vertically adjustable to the longitudinal axis (26) of the transport device (28) arranged feed device (40).

4. Device according to one of the preceding claims, with a transport device (20) which for its forward movement contains a striding device (22, 24, 28, 30) which laterally arranged on the edge of the pipe alley (12) Heizroh¬ ren ( 10) can be supported.

5. Device according to one of the preceding claims, in which a band (52) made of steel is provided.

6. The device according to claim 5, wherein the band (52) has recesses (54) arranged one behind the other in its longitudinal direction, through which the supply line (58, 66, 72) is threaded.

7. The device according to claim 6, in which in the longitudinal direction of the band between the recesses (54) in each case formations (60) for receiving the supply line (58, 66, 72) are introduced, which alternate on one side and the other extend the band (52).

8. Device according to one of the preceding claims, in which a spray head (63) is provided as the processing head, which is connected for supplying a spray liquid to a metal capillary (58) fixed to the belt (52).

9. The device according to claim 8, with a capillary (58) made of a nickel-titanium alloy.

10. The device according to claim 8 or claim 9, wherein a spray head is provided with at least two outlet openings (65) for the spray liquid, which are inclined at mutually different angles (ßa, ßb) against a longitudinal axis (62) of the belt (52) .

11. The device according to one of claims 1-8, in which a recovery tool (70) is provided as the machining head, which can be actuated via a cable pull (72) guided in the band (52).

12. Device according to one of the preceding claims, in which in the band (52) an optical fiber cable (66) for an outdoors End (53) of the lance (50) arranged endoscope (68) is guided.

13. A method for processing or inspecting a tube sheet (6) of a steam generator (2), in which

a) a transport device (20) is introduced into a pipe lane (6) of the steam generator (2), which

b) carries a flexible lance (50) with a flexible band (52), in which at least one flexible supply line (58, 66, 72) for a processing or inspection head () arranged at a free end (53) of the lance (50) 63, 68, 70) is arranged, and on the

c) a feed device (40, 400) for advancing, deflecting and aligning the flexible belt (52) at an angle (α1, α2) to a longitudinal axis (26) of the transport device (20), wherein

d) the flexible band (52) is guided between rollers (41, 42, 43, 44, 410, 420, 430, 440) mounted in the feed device (40, 400), at least one roller (41, 42, 43 , 44, 410, 420, 430, 440) for feeding the belt (52).