CN108180042B

CN108180042B - Method and device for controlling the positioning of a rotor disk around a tie rod

Info

Publication number: CN108180042B
Application number: CN201711268984.1A
Authority: CN
Inventors: R.波斯卡; E.皮格诺内
Original assignee: Ansaldo Energia SpA
Current assignee: Ansaldo Energia SpA
Priority date: 2016-12-05
Filing date: 2017-12-05
Publication date: 2022-08-23
Anticipated expiration: 2037-12-05
Also published as: CN108180042A; IT201600123382A1; EP3330484A1

Abstract

The present disclosure provides a method and apparatus for controlling the positioning of at least one rotor disk (2) around a tie rod (3) of a gas turbine rotor (1); the method comprises the following steps: at least one parameter relating to the position of the rotor disc (2) relative to one or more references is detected by means of a device (15) coupled to the free face (13a) of the rotor disc (2).

Description

Method and device for controlling the positioning of a rotor disc around a tie rod

Technical Field

The invention relates to a method and a device for controlling the positioning of tie rods of a rotor disc around a gas turbine rotor.

Background

A gas turbine rotor of an industrial plant for the production of electrical energy generally comprises a plurality of bladed rotor disks aligned along an axis and coupled at the front. The frontal coupling between adjacent rotor disks is obtained by means of a HIRTH joint.

Each rotor disc is therefore provided with two respective radial rings of teeth, so-called HIRTH teeth sets, one on each face. These rings are coupled to the rings of adjacent discs in order to build a so-called HIRTH joint.

The rotor disc is provided with respective sets of blades and is bound in a stack by a central tie rod, wherein the central tie rod engages a respective central hole of the rotor disc.

Each bladed disk defines a compressor or turbine rotor stage.

Gas turbine rotors must be produced and assembled with the highest precision in order to ensure near perfect balance. Considering the quality and the high rotation speed (the rotor typically rotates at 3000 rpm or 3600 rpm, depending on the standards of different countries), even the smallest defects may cause dangerous vibrations that exceed the admissible limits, thus forcing the plant to stop in order to carry out corrective interventions aimed at bringing the vibrations back to the admissible limits.

The assembly of the rotor currently involves stacking the rotor disks around a central tie rod arranged in a vertical position. The rotor disk automatically centers itself due to the fact that the contact between the disks is achieved by the HIRTH toothing described above.

The assembly of the rotor typically requires stacking a large number of rotor disks (e.g., about twenty). Thus, the lack of uniformity of only one of the discs (for example, due to the fact that the discs have non-parallel faces) is sufficient to obtain a tilted stack at the end of the stacking step, i.e. a stack in which the centre of the last disc is not vertically aligned with the centre of the first disc.

Disc compliance is often controlled when the rotor is already clamped and possible corrective action often requires disassembly of the rotor.

Furthermore, the tools and methods currently available take a long time to evaluate and correct the stack. Before stacking, the compliance of the control discs is checked, but this does not ensure that all non-compliance of the discs is detected, since the operator needs to perform manual activities and personal evaluations. Therefore, the accuracy and time required for the inspection and correction cannot be regarded as satisfactory.

It is therefore important to have a method for controlling the positioning of the tie rods of the rotor disc around the gas turbine rotor which is accurate and reliable and which avoids or minimizes the occurrence of balancing errors. Thereby, evaluation and correction operations to be carried out at the already clamped rotor can be avoided or minimized.

Disclosure of Invention

In accordance with these objects, the present invention relates to a method for controlling the positioning of a tie rod of a rotor disc around a gas turbine rotor; the method comprises the step of detecting at least one parameter related to the position of the rotor disc relative to one or more references.

Another object is to provide a device for controlling the positioning of the tie-rods of the rotor disc around the gas turbine rotor which is precise, reliable and capable of facilitating the operations to be carried out in order to check the compliance of the disc, thus minimizing the manual activities and personal evaluations of the operator.

In accordance with these objects, the present invention relates to a device for controlling the positioning of at least one rotor disk around a tie rod of a gas turbine rotor; the device includes:

a support member;

a centering system configured to center the support on a rotor disk of the rotor;

at least one detection assembly coupled to the support and configured to detect at least one parameter related to a position of the rotor disk relative to one or more references.

Drawings

The invention will now be described with reference to the accompanying drawings, which show non-limiting embodiments thereof, and in which:

FIG. 1 is a side view of a gas turbine rotor having a cross-section along a vertical axial plane;

FIG. 2 is a side view of the rotor of FIG. 1 partially assembled during a step of a method according to the present invention;

FIG. 3 is a perspective view of a detail of the rotor of FIG. 1;

fig. 4 is a plan view from the bottom of the apparatus for assembling a rotor according to the present invention;

FIG. 5 is a plan view from the top of the device of FIG. 4;

FIG. 6 is a cross-section of the device of FIG. 4 along plane VI-VI;

fig. 7 is a schematic block diagram of details of the apparatus of fig. 5.

Detailed Description

In fig. 1, reference numeral 1 indicates a gas turbine rotor of an apparatus for producing electric energy, comprising a plurality of disks 2, these disks 2 being aligned along an axis a and being bound in a plurality of stacks by means of a central tie rod 3. A first group of discs 2 is provided with respective first rotor blades 5, which define a compressor section 1a of rotor 1, whereas a second group of discs 2 is provided with respective second rotor blades 6, which define a turbine section 1b of rotor 1. The compressor section 1a and the turbine section 1b are separated from each other by a disk 2 without blades, which disk 2 essentially acts as a spacer element and is substantially shaped like a cylinder. In use, an annular combustion chamber (not shown) of the gas turbine can be arranged around the spacer disk 2.

With reference to fig. 3, each rotor disk 2 is provided with a central through hole 8 and with a peripheral edge 9, the peripheral edge 9 being provided with a plurality of seats 10, the seats 10 being suitably shaped so as to be coupled to a respective first rotor blade 5, or to a respective second rotor blade 6.

The central bore 8 is engaged in use by the tie rod 3 of the rotor 1.

On each

face

13a, 13b of the rotor disc 2 (in fig. 3 only face 13a of the rotor disc can be seen, whereas face 13b is partially shown in fig. 1 and 2), each rotor disc 2 is also provided with a radial tooth ring 12, generally designated as HIRTH toothing.

Preferably, the radial toothed ring 12 is arranged along a respective face close to the peripheral edge 9 of the rotor disk 2.

The radial toothed ring 12 is positioned and shaped so as to be coupled to the ring of the adjacent rotor disc 2, so as to build a so-called HIRTH joint and to ensure a stable coupling of the rotor discs 2.

Fig. 2 shows the partially assembled rotor 1, in which rotor 1 the tie rods 3 are arranged and supported in a vertical position. Preferably, the tie rod 3 has an end portion which is housed in a stacking recess (not shown for the sake of simplicity), which ensures a correct and stable vertical positioning of the tie rod 3.

The configuration shown in fig. 2 may occur both during assembly of the rotor 1 (when the rotor disks 2 are stacked one on top of the other, so that the radial toothed rings 12 of adjacent rotor disks 2 can be coupled to one another in order to build a HIRTH joint), and during disassembly of the rotor 1 (when the rotor disks 2 are removed one by one).

The method according to the invention for controlling the positioning of at least one rotor disc 2 around a tie rod 3 is suitable for a partially assembled rotor 1 as in the configuration of fig. 2.

In practice, the method comprises detecting at least one parameter relating to the position of at least one rotor disc 2 with respect to one or more references by means of a device 15 coupled to the free face 13a of the rotor disc 2 (in fig. 2, the device 15 is represented schematically as an assemblable disc, more details regarding the device 15 will be described hereinafter with reference to fig. 4).

Here, and in the following, a free face means a face of a rotor disc 2 which is not coupled to another face of an adjacent rotor disc 2.

Thus, the method according to the invention can be applied both during assembly and disassembly of the rotor 1.

During assembly, the position of a disk 2 is detected before another disk 2 is stacked on the controlled disk 2, whereas during disassembly, the position of a disk 2 is detected before the controlled disk 2 is removed.

As a result, the method according to the invention requires that the device 15 is coupled to one rotor disc 2 at a time. However, this does not imply that positioning control must be exercised for each disk of the rotor 1. It is also possible to control the positioning of groups of coupled rotor disks 2 by means of the detection of the position of the rotor disks 2 belonging to the group with free surfaces.

Referring to fig. 4 and 5, the apparatus 15 comprises: a support 16; a centering system 17 configured to center the support 16 on the controlled rotor disc 2; at least one detection assembly 19 coupled to the support 16 and configured to detect at least one parameter related to the position of the rotor disc 2 with respect to one or more references; and a control device 20.

The support 16 is preferably defined by a frame configured to support the centering system 17 and the detection assembly 19.

Preferably, the support 16 is provided with coupling means 18, the coupling means 18 being configured so as to provide hook points for lifting the support 16, for example by means of an overhead crane (not shown).

In the non-limiting example described and shown herein, the coupling means 18 comprise a plurality of small holes 18a, which holes 18a are arranged along the outer edge of the support 16 and can be coupled to a snap ring of a bridge crane (not shown).

In the non-limiting example described and illustrated herein, the support 16 has an annular shape with dimensions compatible with those of the rotor discs 2 and tie rods 3 making up the rotor 1.

In particular, the support 16 is defined by an annular frame, which is so sized as to ensure that the tie-rods can be easily inserted in the support 16.

Referring to fig. 4 and 5, the support 16 has: a first annular face 21 designed to face, in use, the rotor disc 2 to be controlled; and a second annular surface 22 opposite the first annular surface 21.

According to a variant not shown herein, the support 16 comprises a hook device designed to hook the rotor disc 2. The lifting of the support 16 thus determines the lifting of the rotor disc 2 from the hook to the support 16. The hooking means can be defined, for example, by three opposite vices arranged at 120 ° to each other, wherein these vices lock, by expansion, on the radial ring 12 of the rotor disc 2 to be lifted.

With reference to fig. 4, the centering system 17 comprises at least two portions of a HIRTH rim ring 23 which can be coupled to respective portions of a radial tooth (HIRTH) ring 12 arranged on a free face 13a of one of the rotor disks 2 making up the rotor 1.

Portions of the HIRTH rim ring 23 are coupled to the first annular face 21 so as to face, in use, the rotor disc 2 to be controlled.

In order to be coupled to the radial toothed ring 12 of any rotor disc 2 of the rotor 1, portions of the HIRTH rim toothed ring 23 must be shaped so as to have a minimum radius equal to the inner radius of the radial toothed ring 12 of the smallest rotor disc 2 and a maximum radius equal to the outer radius of the radial toothed ring 12 of the largest rotor disc 2.

Furthermore, the portions of the HIRTH edge ring 23 must have a plurality of teeth oriented like the teeth of the radial ring 12, i.e. towards the centre of the rotor disk 2, retaining all the other parameters of the teeth of the radial ring 12 (inclination of the tooth wall, number of teeth, etc.) in order to ensure a correct and stable coupling between the radial ring 12 of the rotor disk 2 and the portions of the HIRTH edge ring 23.

If there is a two-part HIRTH rim ring 23, the two parts are diametrically opposed.

In the non-limiting example described and shown herein, the centering system 17 comprises three portions of the HIRTH rim ring 23, preferably separated from each other by about 120 ° and arranged on the same plane.

The three portions of the HIRTH rim ring 23 are substantially identical.

In this way, a portion of the HIRTH toothing 23 substantially defines a coupling face of the device 16 designed to be arranged in contact with the free face 13a of the rotor disc 2 to be controlled.

Preferably, portions of the HIRTH rim ring 23 are manufactured as one piece with the support 16.

Thereby, the support 16 is coupled in an integral manner to the controlled rotor disc 2 and is centered on the controlled rotor disc 2.

Preferably, a portion of the HIRTH rim ring 23 projects from the first annular face 21 of the support 16, so that the support 16 does not interfere with the radial ring gear 12 of the rotor disk 2 (see the section along the plane VI-VI shown in fig. 6).

In the non-limiting embodiment described and shown herein, the detection assembly 19 comprises: a first device 27 configured to detect at least one parameter related to the inclination of the rotor disc 2 with respect to a horizontal plane; and a second device 28 configured to detect at least one parameter related to the eccentricity of the rotor disc 2 with respect to the tie-rod 3 of the rotor 1 around which the rotor disc 2 is arranged.

In particular, the first device 27 comprises a biaxial inclinometer coupled to the support 16 and able to provide a measurement of the inclination of the support 16 with respect to two orthogonal axes.

Since the support 16 is integral with the rotor disc 2 to which it is coupled, the inclination measurement of the first device 27 reflects the inclination of the rotor disc 2 to which the device 15 is coupled.

For example, the first means 27 are coupled to the second annular face 22 of the support 16.

The second device 28 comprises at least three distance detectors 30, these distance detectors 30 being coupled to the support 16, being arranged in respective points belonging to the same circumference (indicated in dashed lines in fig. 4), and being oriented towards the centre of the circumference. In this way, the distance detector 30 detects the distance in the radial direction with respect to the center of the circumference, and aims at a specific target: a pull rod 3.

In the non-limiting example described and shown herein, the second device 28 comprises three distance detectors 30, which distance detectors 30 are arranged along the circumference at 120 ° with respect to each other and are configured to detect three radial distances R1, R2, R3.

Preferably, the distance detector 30 is coupled to the second annular face 22 of the support 16.

The distance detector 30 is preferably a non-contact detector, for example, a laser triangulation system. At the instant the measurement is carried out, the quantities R1, R2, R3 are detected with very high precision (resolution up to one hundredth of a millimeter).

In use, the distance detector 30 aims the tie rod 3 in a radial direction when the device 15 is coupled to the rotor disc 2. Thereby, the distance detector 30 detects three radial distance values R1, R2, R3 with respect to the tie rod 3.

The data detected by the first device 27 and the second device 28 are sent to the control device 20, which is schematically shown in fig. 5.

The control device 20 is configured to process the data detected by the detection assembly 19 and to provide an evaluation of the positioning of the rotor disc 2.

Referring to fig. 7, the control device 20 preferably includes: a storage module 101 in which all the inclination data detected by the first device 27 are stored successively for different rotor disks 2; a calculation module 102 configured to calculate the relative inclination of each rotor disk 2 with respect to the rotor disk 2 in front of it; and an inclination evaluation module 103 configured to evaluate whether the absolute inclination value detected by the first detection device 27 and the relative inclination value calculated by the calculation module 102 are within respective tolerance limits.

Preferably, the tolerance interval for the relative inclination of the individual rotor disks is +/-1/1000 °.

Preferably, the tolerance interval for the absolute tilt angle is +/-2/100.

The calculation module 102 calculates the relative inclination as the difference between the detected absolute inclinations of the adjacent rotor disks 2.

If the relative inclination and/or the absolute inclination are not within predefined tolerance limits, the control system 20 gives a signal about a fault.

According to an embodiment not shown herein, the control device 20 comprises a further module configured to give an indication about a possible corrective action to be carried out in view of the relative and absolute inclination data stored in the storage module 101.

Preferably, the control device 20 also comprises a comparison module 105 configured to compare the distance data detected by the second device 28 and to signal the occurrence of eccentricity when the difference between the detected distances is greater than a threshold value. Preferably, the threshold is approximately equal to 0.1 mm.

Preferably, the data detected by the first device 27 and the second device 28 are sent to the control device 20 by means of wi-fi communication.

Preferably, as can be seen schematically in the figures, the control device 20 is not coupled to the support 16 and is integrated in an external processor (for example, a tablet computer) available to the operator engaged in the assembly/disassembly of the rotor 1. The tablet computer is thus able to provide the operator with information of the correct positioning of the discs on the stack (with respect to all tolerances), and in any case store the information.

With reference to fig. 2, the device 15 is also provided with a pointer 35, the pointer 35 being coupled to the support 16 and configured to generate a light beam in a given direction towards the outside of the support 16.

The beam thus generated can be used to provide a reference of the angular position of the device 15.

Preferably, in addition to the rotor 1, there is a reference element 36, the reference element 36 extending along a vertical axis.

The reference element can be defined by any fixed element close to the rotor 1 that can be used as a reference point.

The pointer 35 thus allows to always arrange the device 15 in the same angular position with respect to the tie rod 3 for each detection.

Preferably, when the device is coupled to the rotor disc 2 under control, the fingers 35 are configured so as to generate a substantially horizontal and radial beam.

Advantageously, the device 15 and the method for controlling the positioning of rotor disks according to the present invention allow to improve and optimize the assembly of the rotor 1, thus avoiding the assembly of an unbalanced rotor, and in particular avoiding the costs caused by one or more corrective interventions to be carried out on an already assembled rotor.

The device 15 and the method for controlling the positioning of rotor discs according to the present invention can also be applied to already assembled rotors assembled with previous assembly techniques.

In the case of an already assembled rotor, the device 15 and the method according to the invention can be applied during disassembly of the rotor 1 from disc to disc.

During disassembly, one rotor disc 2 at a time is removed and the device 15 is used to detect the position of each rotor disc 2 until the rotor disc (or rotor discs) responsible for the unbalance of the rotor 1 is found.

The application of the device 15 during the disassembly of the rotor 1 is advantageous compared to the solutions known today, because it gives an objective indication about the positioning of each rotor disc 2 without introducing a personal evaluation element of the operator.

Furthermore, for example, it is not necessary to completely disassemble the rotor 1 in the following cases:

if before all the rotor disks are removed, the rotor disk 2 responsible for the imbalance is identified;

if at least two disks or two groups of disks (possibly even non-adjacent disks) are identified, these disks have an inclination angle which is such as to be able to be compensated by a suitable corrective action (i.e. a rotation relative to the axis a of the group of disks or of one of the disks), which brings the stack of rotor disks as a whole back into alignment within a given tolerance.

Basically, the identification of an unbalance does not necessarily lead to a replacement of the rotor disk 2. In fact, the unbalance can be simply corrected by means of a suitable rotation of the rotor disk. In this case, the device 16 plays an important role in establishing whether the corrective action is effective and sufficient to compensate for the imbalance.

Finally, it is clear that the device and the method described herein are susceptible to variations and changes without thereby departing from the scope of protection of the appended claims.

Claims

1. A method for controlling the positioning of tie-rods (3) of at least one rotor disk (2) around a partially assembled rotor (1) of a gas turbine; the method comprises the following steps: detecting at least one parameter related to the position of the rotor disc (2) with respect to one or more references by means of a device (15), the device (15) being coupled to a free face (13a) of the rotor disc (2) and comprising:

a support (16);

a centering system (17) configured to center the support (16) on the rotor disc (2) of the rotor;

at least one detection assembly (19) coupled to the support (16) and configured to detect at least one parameter related to the position of the rotor disc (2) with respect to the one or more references.

2. A method according to claim 1, wherein the step of controlling the positioning of at least one rotor disc (2) comprises detecting at least one parameter related to the inclination of the rotor disc (2) with respect to a horizontal plane and/or at least one parameter related to the eccentricity of the rotor disc (2) with respect to the tie rods (3).

3. A method according to claim 2, wherein detecting at least one parameter relating to the inclination of the rotor disc (2) with respect to a horizontal plane comprises measuring the inclination by means of an inclinometer associated with the device (15), the inclinometer being integral with the rotor disc (2).

4. Method according to claim 2, wherein detecting, by means of the device (15), at least one parameter related to the eccentricity of the rotor disc (2) with respect to the tie rods (3) comprises detecting the radial distances (R1, R2, R3) with respect to the tie rods (3) of at least three points belonging to the same circumference.

5. Method according to claim 4, wherein detecting, by means of the device (15), at least one parameter relating to the eccentricity of the rotor disc (2) with respect to the tie rods (3) comprises detecting the radial distance (R1, R2, R3) with respect to the tie rods (3) of three non-aligned points belonging to the same circumference and arranged at 120 ° with respect to each other.

6. A method according to claim 4 or 5, wherein detecting at least one parameter relating to the eccentricity of the rotor disc (2) relative to the tie rod (3) comprises: comparing the detected radial distances; and when the difference between the detected radial distances is greater than a threshold value, signaling the occurrence of eccentricity.

7. A device for controlling the positioning of tie rods (3) of at least one rotor disk (2) around a partially assembled rotor (1) of a gas turbine; the device is coupled to a free face (13a) of the rotor disc (2) and comprises:

a support (16);

-a centering system (17) configured to center the support (16) on a rotor disc (2) of the rotor;

at least one detection assembly (19) coupled to the support (16) and configured to detect at least one parameter related to the position of the rotor disc (2) with respect to one or more references.

8. An arrangement according to claim 7, wherein the centering system (17) comprises at least two portions of a HIRTH rim ring (23) which are couplable to respective portions of a radial ring gear (12) arranged on the free surface (13a) of the rotor disc (2).

9. The device according to claim 8, wherein the support (16) comprises the portion of the HIRTH rim ring (23) of the centering system (17).

10. An arrangement according to any of claims 7 to 9, wherein the detection assembly (19) comprises at least one first arrangement (27), which first arrangement (27) is configured to detect at least one parameter related to the inclination of the rotor disc (2) with respect to a horizontal plane.

11. The device according to claim 10, wherein the first device (27) comprises a biaxial inclinometer.

12. The device according to any one of claims 7 to 9, wherein the detection assembly (19) comprises at least one second device (28), the second device (28) being configured to detect at least one parameter related to the eccentricity of the rotor disc (2) with respect to the tie-rods (3) of the rotor (1) around which the rotor disc (2) is arranged.

13. Device according to claim 12, wherein said second device (28) comprises at least three distance detectors (30), these distance detectors (30) being coupled to said support (16) and being arranged in respective points belonging to the same circumference; the distance detector (30) is oriented such as to detect a radial distance (R1, R2, R3) in a radial direction with respect to the tie rod (3).

14. The device according to claim 13, wherein the three distance detectors (30) are arranged at 120 ° with respect to each other along the circumference.

15. An apparatus according to claim 12, comprising a control device (20), the control device (20) being configured to process data detected by the detection assembly (19) and to provide an evaluation of the positioning of the rotor disc (2).

16. The device according to claim 15, wherein the control device (20) comprises a comparison module configured to compare the radial distances (R1, R2, R3) detected by the second device (28) and to signal the occurrence of eccentricity when the difference between the detected distances is greater than a threshold value.