JPH0129248B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention measures the stress generated in a flexible joint provided between the shafts of a combined cycle plant in which equipment such as a compressor, gas turbine, generator, and steam turbine is arranged on one axis. The present invention relates to an abnormality diagnosing device for a shaft system of a combined cycle plant, which compares and determines the stress value with an allowable stress value during normal operation, diagnoses abnormality in the flexible joint, and controls the operating conditions of each of the devices.

As a power generation plant that is highly efficient and can respond to peak loads, a combined cycle plant in which equipment such as a compressor, gas turbine, generator, and steam turbine are arranged on a single shaft has traditionally been used as an effective power plant. ing. During operation of a combined cycle plant, the casings and rotor shafts of the above-mentioned devices undergo thermal expansion, and the difference in expansion causes the spaces between the above-mentioned devices to become clogged, and large stresses are generated in the shaft portions between the devices. Therefore, in order to prevent the generation of this stress, flexible joints are provided between the devices, and the stress is absorbed by this flexure. Generally, a diaphragm coupling having a diaphragm is employed as the flexible joint in combined cycle plants. Various forces act on the diaphragm of this diaphragm coupling during operation, such as tensile or compressive stress, bending stress, etc. These stresses may cause the diaphragm to break, resulting in the diaphragm coupling flying off, which is extremely dangerous. For this reason, preventive measures have traditionally been adopted. As methods for this, methods have been adopted, such as directly attaching stress measuring means such as strain gauges to the diaphragm, and methods that monitor the vibration state of the diaphragm coupling, but both methods are difficult to accurately determine damage to the diaphragm. It had the disadvantage that it was difficult to

That is, as shown in FIG. 1, a combined cycle plant 100 includes a compressor 1, a gas turbine 2, a generator 3, and a steam turbine 4 arranged in series on one shaft 101. The advantage of this combined cycle plant is that it is easy to adjust the output of the gas turbine 2 and the steam turbine in accordance with load fluctuations on the user side, and to adjust the output of the single generator 3 appropriately. Compared to a system equipped with such equipment, it is possible to cope with peak loads more smoothly, and it is also superior in terms of maintenance management.

A bearing, a flexible joint, etc. are arranged on the shaft 101.
That is, a thrust bearing A is installed at one end of the compressor 1.
7 and a radial bearing 9 are provided, and a thrust bearing A
7 regulates the thermal expansion of the compressor 1 etc. in this direction. A rotor shaft at one end of a gas turbine 2 is connected to the other end of the compressor 1 via a radial bearing 9 . A rotor shaft at one end of a generator 3 is connected to a rotor shaft at the other end of the gas turbine 2 via a rigid coupling 5 . Further, these rotor shafts are supported by radial bearings 9. The rotor shaft at the other end of the generator 3 is supported by a radial bearing 9 and is connected to the rotor shaft at one end of the steam turbine 4 through a flexible joint 6 . Note that a thrust bearing B8 is provided between the flexible joint 6 and the rotor shaft on one end side of the steam turbine 4. Further, the rotor shafts at one end and the other end of the steam turbine 4 are supported by radial bearings.

During operation, the rotor shafts of the gas turbine 1 and the generator 3 elongate due to thermal expansion, and this elongation occurs from the thrust bearing 7 as a base point toward the steam turbine 4 side. Of course, the not-illustrated casings of the gas turbine 2 and the generator 3 also undergo thermal expansion, but the gas turbine 2 and the generator 3 are designed so that the difference in expansion between the casings and their rotor shafts will not hinder operation. As described above, the added difference in expansion between the casing and rotor shaft of the gas turbine 2 and the generator 3 acts on the steam turbine 4 side, but if there is no thrust bearing B8, this added difference in expansion will affect the steam turbine 4. In order to act,
It becomes necessary to provide a large gap in the axial direction between the casing of the steam turbine 4 and the rotor shaft. The above elongation difference reaches 30 m/m to 45 m/m due to the high temperature of the gas turbine 2, and providing a gap corresponding to this elongation difference between the casing of the steam turbine 4 and the rotor shaft maintains the performance of the steam turbine 4. It is considered impossible from this point of view. Therefore, as described above, the thrust bearing B8 is provided to restrict the influence of the difference in expansion on the steam turbine 4 side, and the flexible joint 6 is connected to the radial bearing 9 on the other end side of the generator 3 and the thrust bearing B8. It is necessary to provide a space in between.

As the flexible joint 6, a gear coupling 102 shown in FIG. 2 and a diaphragm coupling 106 shown in FIG. 3 are employed.

The gear coupling spring 102 includes a sleeve A17 in which a gear 17a is formed on the outer periphery of the flange on both ends, and an arcuate crowning is formed in the thickness direction of the flange, and an internal gear that meshes with the gear 17a of the sleeve A17. and a cover A30 that meshes with the gear 17a of the sleeve A17;
and a coupling boss A32 which is connected by a bolt A31 and forms a hole into which the rotor shaft is inserted. The gear coupler 102 is configured such that the cover A30 meshes with the gear 17a of the sleeve A17 and moves in the axial direction thereof, and rotates around the gear 17a to absorb the difference in expansion and act as a coupler. has been done. However, as mentioned above, the gear coupling 102 does not have a flexible member and is constructed by coupling solid members, so alignment errors are likely to occur during coupling, and the gear 17a
The shaft center tends to become misaligned due to wear. Further, there is a drawback that vibration is likely to occur when starting up, and it takes a lot of time to balance the device to prevent this.

On the other hand, as shown in FIG. 3, the diaphragm coupling 106 is made up of a sleeve B15 provided with the diaphragm 14 at both ends, a coupling boss B11 and a diaphragm cover B12 that clamp the outer peripheral side of the diaphragm 14 via bolts B13. The rotor shaft 16 at the other end of the generator 3 or the rotor shaft 10 at one end of the steam turbine 4 is fitted into the coupling boss B11. The diaphragm coupling 106, which was held at a distance L as shown in FIG. 4a, absorbs the above expansion difference x, and the diaphragm 14 deforms as shown in FIG. 4b.
It is compressed in its axial direction and held at a distance L-x.
Further, when the axis is deviated by a displacement δ, the diaphragm 14 is torsionally deformed and absorbs the displacement δ while maintaining the distance L approximately, as shown in FIG. (The center line is attached to each figure, and the hatching indicating the cross section is omitted.) As described above, the above expansion difference x and displacement δ are easily absorbed by the diaphragm 14, which is a flexible member, and only a small thrust reaction force is generated. In addition, the diaphragm coupling 106 has come to be adopted as the flexible joint 6 in combined cycle plants because it has many advantages such as being used without lubrication and only needing to be balanced once. There is.

However, when employing this diaphragm coupling 106, reliability of the diaphragm 14 becomes a problem. As mentioned above, the diaphragm 14 is susceptible to centrifugal stress caused by centrifugal force, torsional stress for torque transmission, and tensile or compressive stress due to axial displacement due to the above-mentioned elongation difference or displacement caused by alignment defects. Bending stress acts. If the diaphragm 14 is damaged during operation due to the effects of various stresses, not only will the diaphragm coupling 106 be scattered, but the generator 3
The rotor shaft 16 of the steam turbine 4 and the parts around the rotor shaft 10 of the steam turbine 4 are damaged, and an unfathomable accident occurs in which the parts are scattered. Therefore, it is necessary to diagnose the abnormality of the diaphragm 14.
This abnormality diagnosis means has been employed in the past as well. As one means for this, the diaphragm 14
A method of diagnosing abnormalities by attaching a strain gauge directly to the surface of the material and measuring the stress has been adopted. However, diaphragm 14 usually has 3000r.pm or
Since it rotates at a high speed of 3,600 rpm, centrifugal acceleration of 5,000 G or more acts on it, so it has the disadvantage that it is difficult to reliably bond and hold the strain gauge on the surface of the diaphragm 14. Furthermore, the distance between the strain gauge and a telemeter for detecting the measured value of the strain gauge becomes long, resulting in a reduction in detection accuracy. Furthermore, the diaphragm 14 does not necessarily break only from the surface, and it also has the disadvantage that the discovery of abnormalities is delayed.

Further, as another means, there is a method for diagnosing an abnormality in the diaphragm 14 by monitoring vibrations of various parts of the diaphragm coupling. However, diaphragm 1
In some cases, the damage in item 4 does not directly lead to vibration.
This method has the disadvantage that abnormalities in the diaphragm 14 cannot be accurately diagnosed.

In addition, both of the above methods focus too much on only abnormality diagnosis of the diaphragm coupling 106, and do not target the reaction force applied to the thrust bearing B8, so they are not effective in diagnosing the overall abnormality of the combined cycle plant shaft system. However, it had the disadvantage of being insufficient.

The present invention was devised to solve the above-mentioned drawbacks, and its purpose is to accurately diagnose abnormalities in flexible joints installed between devices, and to use the diagnostic results to determine the operating conditions of the devices. An object of the present invention is to provide an abnormality diagnosis device for a shaft system of a combined cycle plant, which adjusts and prevents the occurrence of abnormalities in the shaft system.

In order to achieve the above object, the present invention provides a stress measuring means on a shaft between equipment such as a generator or a steam turbine having a flexible joint, detects this stress signal by a detecting means, and detects the stress signal. The input is input to the calculation means provided on the fixed side of the above equipment, and the stress value generated in the flexible joint is converted, and the allowable stress value generated in the flexible joint during normal rated operation is determined, and this allowable stress value and the above The present invention is characterized by an abnormality diagnosis device for a shaft system of a combined cycle plant, in which the stress value is compared and determined by a comparing means and a determining means, and the operating conditions of the above-mentioned equipment are controlled based on the results.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

First, an outline of this embodiment will be explained.

As shown in FIG. 1, a flexible joint 6 is provided between the generator 3 and the steam turbine 4, and this flexible joint employs a diaphragm coupling 106 as shown in FIGS. 3 and 5. There is. In FIG. 5, a strain gauge 18 serving as stress measuring means is attached to the outer peripheral surface of the sleeve B15.
The strain gauge 18 is engaged with a detection means 19 of a telemeter type that detects the amount of strain and transmits a detection signal thereof. The amount of strain detected by the detection means 19 is input to the receiver 20 as shown in FIG.
22. Arithmetic unit A21 converts the above strain amount into a stress value. The calculator B22 has a diaphragm 1 corresponding to the stress value generated in the sleeve B15 in advance.
Since conversion factors such as axial reaction force and bending moment value acting on sleeve B are stored,
The values of the axial reaction force and bending moment acting on the diaphragm 14 can be determined from the stress value generated at the diaphragm 15 . On the other hand, in the comparison means 23, in advance,
Allowable values such as the axial reaction force and bending moment value of the diaphragm 14 during normal rated operation are stored, and these allowable values and the actual measured values are compared. Next, this comparison signal is input to the determination means 24, and if the actual measured value exceeds the allowable value, a signal is sent to the operation control means 25. A signal is sent to the operation control means 25. Operation control devices 25a, 25b, etc. that engage with the gas turbine 2, steam turbine 4, etc. are connected to the operation control means 25, and control signals from the operation control means 25 are transmitted to these operation control devices 25a, etc. The output of the turbine 2, the steam turbine 4, etc. is adjusted, and the load of the generator 3 is adjusted. As a result, the stress applied to the diaphragm 14 is reduced, and damage to the diaphragm coupling 106 and abnormalities in the shaft system of the combined cycle plant can be avoided.

Next, this embodiment will be explained in more detail.

As shown in FIGS. 5 and 6, a strain gauge 18 serving as stress measuring means is attached to the outer peripheral surface of the sleeve B15 of the diaphragm coupling 106. Although the strain gauges 18 are simply shown in FIG. 5 and the like, a plurality of strain gauges 18 are arranged so as to be able to detect the amount of strain in the axial direction and the bending direction of the sleeve B15. Detection means for detecting the amount of strain in the strain gauge 18 and extracting it to the fixed side of the device include those using a well-known telemeter method and those using a slip-ring method, but in this embodiment, as shown in the figure, A telemeter type detection means 19 is disposed in engagement with the strain gauge 18.

Next, as shown in Fig. 6, there is a receiver 2 on the fixed side.
0, arithmetic unit A21 and arithmetic unit B2 which are calculation means
2. Comparing means 23 and determining means 24 are provided, respectively. The distortion amount signal detected by the detection means 19 is input to the receiver 20 . Then, the distortion amount signal is input to the computing unit A21. Generally, within the elastic limit, the amount of strain is proportional to the stress, so by storing a certain conversion coefficient in advance, the amount of strain can be converted into a stress value. Furthermore, if the function of the axial stress of the diaphragm 14 corresponding to the axial stress of the sleeve B15 of the diaphragm coupling 106 is determined in advance, the force acting in the axial direction of the diaphragm 14 can be determined by the calculator A21. . However, as shown in FIG. 4C, the diaphragm coupling 106 often undergoes a displacement δ, and stress not only in the axial direction but also in the bending direction acts on the sleeve B15, and naturally the diaphragm 14 also undergoes an axial reaction. Forces and bending moments act.

In FIG. 7, the horizontal axis represents time T, and the vertical axis represents stress (tensile stress σ _T , compressive stress σ _C ) applied to the sleeve B15. When the sleeve B15 is subjected to simple tension, as shown by straight line A, the time T
A constant tensile stress acts regardless of the Therefore, as described above, the axial reaction force of the diaphragm 14 can be determined by the calculator A21.

However, on the other hand, in the case shown in FIG. 4c, stress as shown by curve B in FIG. 7 acts. The calculator B22 converts the axial reaction force applied to the diaphragm 14 and the bending moment in such a case. As shown in the figure, the curve B progresses while changing in a wavy manner over time T. The average stress σ _M is obtained by integrating the stress of curve B within a set unit time and dividing this by the above unit time. or,
The stress amplitude σ _F can be determined by determining the difference between the maximum stress and the minimum stress within a unit time. The axial reaction force of the diaphragm 14 is converted by the average stress σ _M , and the value of the bending moment applied to the diaphragm 14 is determined by the stress amplitude σ _F. By the same means, a nonlinear curve that is not synchronized with the rotational speed different from the curve B in FIG. 7 can also be obtained.

On the other hand, in the comparison means 23, the axial reaction force and bending moment values applied to the diaphragm 14 during normal rated operation are obtained by actual measurement or calculation;
This is set as the allowable value of the diaphragm 14 and is stored in advance. Then, the permissible value is compared with the above-mentioned actual measurement value, and the comparison signal is input to the determining means 24. When the actual measured value exceeds the allowable value, the determining means 24
It is configured to issue a signal to the operation control means 25. FIG. 8 illustrates the above-mentioned engagement path using a block diagram.

Further, as shown in FIG. 6, operation control devices 25c, 25a, and 25b are engaged with the compressor 1, gas turbine 2, and steam turbine 4, respectively. The signal inputted from the determination means 24 to the operation control means 25 is analyzed here. Based on this analysis result, each operation control device 25a is sent to the operation control means 25.
Control commands are sent to etc. With this directive,
The operating conditions of the gas turbine 2 and the like are controlled, such as reducing the input, stopping, and reducing the rotational speed.

The attachment of the strain gauge 18 to the sleeve B15 is much more reliable than the conventional technique in which the strain gauge is attached directly to the diaphragm 14, and strain changes can be accurately grasped. Also, arithmetic unit A2
1. The axial reaction force and bending moment value of the diaphragm 14 can also be accurately grasped by the calculator B22. Therefore, the difference between the actual measured value and the allowable value of the diaphragm 14 is accurately grasped, and if the actual measured value exceeds the allowable value, the operating conditions of each device are adjusted immediately, so that abnormalities in the diaphragm 14 can be detected immediately. It will be canceled. As a result of the above, the occurrence of abnormality in the shaft system of the combined cycle plant is eliminated.

In addition, the axial reaction force applied to the diaphragm 14 is
Since this corresponds to the axial force acting on the thrust bearing B8, the above control simply applies to the diaphragm 1.
This not only prevents damage to item 4, but also prevents seizure of the thrust bearing B8 and prevents abnormalities in the shaft system of the combined cycle plant.

Next, another example will be described.

In the above embodiment, the strain gauge 18 was attached only to one location on the outer peripheral surface of the sleeve B15 of the diaphragm coupling 106, but in this embodiment, the sleeve B15 on the opposite side of the strain gauge 18 is attached as shown in FIG. A strain gauge 18a is mounted on the outer circumferential surface of. In this case, as shown in FIG. 9, stress modes of curves C and D are obtained with respect to changes in time T. By finding the average value of the stress between curve C and curve D, the average stress σ _T can be found, and the axial reaction force can be found regardless of the change in time T, and the accuracy of the value of the average stress σ _T can also be determined. improves.

Of course, the strain gauges 18 are not limited to the two locations mentioned above, and a plurality of strain gauges can be used to further improve accuracy.

Next, in all of the above embodiments, the strain gauge 18 is connected to the sleeve B1 of the diaphragm coupling 106.
5, but as shown in FIGS. 5 and 6, it may be installed at any location between the thrust bearing B18 and the radial bearing 9, for example, on the rotor shaft 16 at the other end of the generator 3. Strain gauge 18b
A strain gauge 18c may be attached to the rotor shaft 10 at one end of the steam turbine 4. As above, these strain gauges 18
Based on the detected values of b and 18c, it is possible to diagnose an abnormality in the diaphragm 14 by means similar to those described above.

FIG. 10 shows a block diagram of yet another embodiment. In the figures, the same reference numerals indicate the same means as in the above embodiment.

As mentioned above, the diaphragm coupling 106
is given the expansion and contraction corresponding to the difference in expansion. This expansion difference value 27 is proportional to the output value 28 of the generator 3 and the like. Therefore, the output value 28 during normal rated operation
An elongation difference value 27 corresponding to the diaphragm 14 is obtained by actual measurement or calculation, and based on this, the allowable value of the axial reaction force of the diaphragm 14 is converted by the calculator C26, and this value is transmitted to the comparison means 23. The comparison means 23 compares this allowable value with the actual measured value in the same manner as in the above embodiment, and can diagnose an abnormality in the diaphragm coupling 106.

In the above embodiments, the diaphragm coupling 106 was provided only between the generator 3 and the steam turbine 4, but the present invention is not limited thereto. Furthermore, the stress measuring means is of course not limited to strain gauges.

As is clear from the above explanation, according to the present invention, abnormalities in flexible joints provided between equipment such as generators and steam turbines can be accurately diagnosed, and based on the results, abnormalities in flexible joints provided between equipment such as generators and steam turbines can be accurately diagnosed. It is possible to control operating conditions, prevent damage to flexible joints, and prevent abnormalities in the shaft system of a combined cycle plant.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a combined cycle plant, Figure 2
The figure is a cross-sectional view showing the configuration of the gear coupling.
The figure is a sectional view showing the structure of the diaphragm coupling, Figures 4a to 4c are explanatory diagrams showing the operation of the diaphragm coupler, and Figure 5 is a state in which a stress measuring means is attached to the diaphragm coupler according to an embodiment of the present invention. 6 is a configuration diagram of the embodiment, FIG. 7 is a diagram showing the stress distribution state in the embodiment, and FIG. 8 is a block diagram explaining the operation of the embodiment. FIG. 9 is a diagram showing the stress distribution in another embodiment, and FIG. 10 is a block diagram explaining the operation of still another embodiment. 1... Compressor, 2... Gas turbine, 3... Generator,
4... Steam turbine, 6... Flexible joint, 7... Thrust bearing A, 8... Thrust bearing B, 9... Radial bearing, 10... Rotor shaft on the steam turbine side, 11... Coupling boss B, 12... Diaphragm cover B,
13...Bolt B, 14...Diaphragm, 15...Sleeve B, 16...Rotor shaft on generator side, 18,1
8a, 18b, 18c...Strain gauge, 19...Detection means, 20...Receiver, 21...Arithmetic unit A, 22...Arithmetic unit B, 23...Comparison means, 24...Judgment means, 25...
Operation control means, 25a, 25b, 25c... Operation control device, 26... Arithmetic unit C, 27... Differential expansion value, 28
...Output value, 106...Diaphragm coupling.

Claims (1)

[Claims] 1. A gas turbine, a generator, and a steam turbine are arranged on one axis, a flexible joint is provided between each device, the stress on the axis is measured, and an abnormality in the flexible joint is diagnosed. In an abnormality diagnosis device for a shaft system of a combined cycle plant, a stress measuring means is provided on the shaft, the stress signal is inputted by the detection means to the calculation means provided on the fixed side of the equipment, and the calculation means Calculating the stress value acting on the flexible joint, determining the allowable stress value of the flexible joint during normal rated operation, comparing and determining the allowable stress value and the stress value using a comparing means and a determining means, A system for diagnosing abnormality in a shaft system of a combined cycle plant, characterized in that the determination signal is inputted to an operation control means that engages with each of the devices to control the operating conditions of each of the devices. 2. The flexible joint consisting of a diaphragm coupling is provided between the generator and the steam turbine,
The combined cycle plant according to claim 1, wherein the stress measuring means is attached to the diaphragm support portion of the diaphragm coupler, and the stress value generated in the diaphragm of the diaphragm coupler is converted. Axial system abnormality diagnosis device. 3. A combined cycle plant characterized by being configured to determine the difference in elongation between the shafts of each of the devices during normal operation, and calculate the allowable stress value generated within the flexible joint from the difference in elongation. Axial system abnormality diagnosis device.