CN115541114A - Dynamic balance method for eliminating unstable vibration of shafting - Google Patents
Dynamic balance method for eliminating unstable vibration of shafting Download PDFInfo
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- CN115541114A CN115541114A CN202211075848.1A CN202211075848A CN115541114A CN 115541114 A CN115541114 A CN 115541114A CN 202211075848 A CN202211075848 A CN 202211075848A CN 115541114 A CN115541114 A CN 115541114A
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- 230000001105 regulatory effect Effects 0.000 claims description 6
- 238000012360 testing method Methods 0.000 claims description 6
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 238000012423 maintenance Methods 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 238000010183 spectrum analysis Methods 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims 2
- 241001669679 Eleotris Species 0.000 claims 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M1/00—Testing static or dynamic balance of machines or structures
- G01M1/30—Compensating imbalance
- G01M1/32—Compensating imbalance by adding material to the body to be tested, e.g. by correcting-weights
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M1/00—Testing static or dynamic balance of machines or structures
- G01M1/14—Determining imbalance
- G01M1/16—Determining imbalance by oscillating or rotating the body to be tested
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M1/00—Testing static or dynamic balance of machines or structures
- G01M1/30—Compensating imbalance
- G01M1/36—Compensating imbalance by adjusting position of masses built-in the body to be tested
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Abstract
The invention provides a dynamic balance method for eliminating unstable vibration of a shafting, which can conveniently and effectively solve the problem of abnormal vibration of a high-medium pressure rotor commonly seen in a specific type of unit. According to the shafting vibration characteristics of the type of unit, the method creatively adopts the synchronous balance of the high and medium pressure rotors across the inner span and the outer span and multiple balance planes, and can eliminate the abnormal vibration of the high and medium pressure rotors caused by the reduction of the stability of the shafting by applying the balance weight once by using a specific calculation method. The method reduces the number of the start and stop times of the unit in the vibration fault processing process to the maximum extent, and is a dynamic balance method which is effectively used for eliminating the abnormal vibration of the steam turbine generator unit through practical inspection.
Description
Technical Field
The invention relates to a dynamic balance method for eliminating unstable vibration of a shafting, belonging to the technical field of steam turbine shafts.
Background
The abnormal vibration reasons of a large-capacity steam turbine shafting are complex, the load of a high-medium pressure rotor bearing is relieved due to the uneven settlement of a steam turbine foundation in long-term operation, the dynamic change of a bearing pedestal elevation in hot-state operation and the like, a bearing oil film is poor in formation, and the vibration is increased due to the reduction of the oil film rigidity. In the sequence valve mode of operation, uneven airflow forces may also cause flow excitation of the high and medium pressure rotors. Due to the reasons, the difficulty of analyzing and processing the original vibration data is high when the high-medium-pressure rotor works in a field in a high-speed dynamic balance mode.
Disclosure of Invention
The invention aims to provide a dynamic balance method for eliminating unstable vibration of a shafting, which can eliminate power frequency vibration caused by unbalanced rotor mass to the maximum extent and ensure that a unit can run safely and stably.
In order to achieve the purpose, the invention is realized by the following technical scheme:
step l: and (4) overhauling and adjusting front and rear bearings of the high-medium pressure rotor of the large-capacity steam turbine, and taking the lower limit of the mounting standard value as the top clearance of the bearings.
And 2, step: testing the journal lift of the high-medium pressure rotor under the condition of not removing a coupler, comparing the journal lift with maintenance records during installation, and adjusting a corresponding numerical value of the journal lift on the basis of an installation standard value for compensation according to a variable numerical value of the journal lift during reinstallation and a metal temperature difference value of front and rear bearings of the high-medium pressure rotor in an operating state; because the basic settlement amount and the raise degree variable amount of different units are different, the number is not uniform and needs to be flexibly determined according to the actual conditions of the units and the field processing experience.
And step 3: the valve sequence of the sequence valve is changed into a diagonal air inlet mode, so that the offset of the rotor in the horizontal direction is reduced; when the direction from the steam turbine to the generator and the rotation direction of the rotor are clockwise, the regulating gates opened in the third sequence at high load are changed into the regulating gates at the right lower part of the stress direction of the rotor; the stress condition of the rotor is improved, the floating amount of the rotor towards the upper left side under high load is reduced, and the oil film rigidity of the bearing in the direction is improved.
And 4, step 4: carrying out frequency spectrum analysis on shaft vibration of front and rear bearing measuring points of the high and medium pressure rotor to find out a power frequency vibration component in the shaft vibration; and carrying out homodromous vector and reverse vector decomposition on the high and medium voltage rotor vibration modes.
If the first-order mode is mainly the vibration mode, a group of counterweights with the same phase are applied to the balancing holes at the two inner ends of the span of the high and medium pressure rotor, and because the weighted radius of the balancing position is smaller and the positions of the balancing holes are dispersed, a group of counterweights with the phase opposite to that of the counterweights in the span of the inner counterweight needs to be applied to the balancing holes of the long shaft coupling at the front end of the high and medium pressure rotor at the same time.
If the second-order mode is mainly the mode, a group of counterweights with opposite phases are applied to the balance holes at the two ends of the span of the high-medium pressure rotor, and a group of counterweights with the same phase as the counterweights at the front end of the span of the high-medium pressure rotor are applied to the balance holes at the front end of the high-medium pressure rotor and the long shaft coupling.
Preferably, the contact area of the tile pillow sizing block is controlled to be more than 75% in the step 1 and is uniformly distributed.
The invention has the advantages that:
(l) The abnormal vibration of the high and medium pressure rotor of the large-capacity steam turbine is mainly characterized in that the vibration frequency spectrum is complex, and the abnormal vibration not only contains power frequency vibration caused by unbalanced rotor mass, but also low frequency vibration caused by air flow excitation, and sometimes frequency doubling vibration caused by defects such as rotor microcracks and the like. The dynamic balancing method aims to find out power frequency components in a complex vibration frequency spectrum, and eliminate power frequency vibration caused by rotor mass unbalance to the maximum extent by a counterweight means, so that a unit can run safely and stably.
(2) The reduction of the shafting stability can reduce the dynamic rigidity of the support system, thereby amplifying the vibration amplitude. Therefore, the dynamic balance method firstly adopts measures to enhance the stability of the shafting and improve the dynamic rigidity of the support system, thereby obtaining more accurate vibration components caused by the unbalance of the rotor mass.
(3) In the field dynamic balance work of the high-medium pressure rotor of the large-capacity unit, the counterweight effect is often limited due to the limitation of the positions of the dynamic balance planes at the two ends of the rotor. The dynamic balance method selects proper cross-external dynamic balance planes for combination according to the shafting structure and the vibration mode characteristics of the rotor, and can obtain better dynamic balance effect by applying a combined balance weight once by using a specific calculation method.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
FIG. 1 is a schematic view of a partial shafting structure of a steam turbine according to the present invention.
FIG. 2 is a schematic view of the high-pressure regulating door and the direction of the circumferential airflow.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention is further explained by taking the field dynamic balance test of a 660MW steam turbine generator unit in a power plant as an embodiment.
The structure of the turbine shafting of the unit is shown in figure 1. The direction of rotation of the rotor is clockwise as viewed from the turbine to the generator.
The high-medium voltage rotor overcritical vibration and the loaded vibration of the unit are continuously increased after 168-hour debugging and production are completed, power frequency and low frequency vibration continuously increase, finally, the shaft 1 is vibrated to increase speed and overcritical vibration to reach 200 mu m, and tripping is caused by the protection fixed value that the shaft 1 is vibrated to exceed 254 mu m in the high-load process. The metal temperature of the No. 1 bearing is 10 ℃ lower than that of the No. 2 bearing in operation, the phenomenon of uneven settlement of the turbine foundation is found through measurement, and the settlement of the foundation near the No. 1 bearing seat is 2mm more than that of the foundation of the No. 2 bearing seat.
(l) The No. 1 bearing of the unit is a four-pad tilting pad, and the scraping treatment is carried out after the local abrasion of the alloy contact surface of the lower pad of the No. 1 bearing is detected. The installation standard value of the top clearance of the bearing is less than 0.7mm, the lower limit is taken during the re-installation, and the left side of the actually measured top clearance is 0.61mm and the right side is 0.62mm. And the contact area of each sizing block of the tile pillow is controlled to be more than 75 percent and is uniformly distributed.
(2) The shaft neck raise of the high-medium pressure rotor is measured again without disassembling the shaft coupling, the raise of the No. 1 shaft neck is 0.3mm/m, the raise of the No. 2 shaft neck is 0.1mm/m, the data is shown in the table 1, and the raise of the No. 1 shaft neck is obviously reduced. According to the foundation settlement and the raise degree change data of the unit, a space for uneven settlement is reserved properly in the overhaul before the dynamic balance test, and the raise degree value of the No. 1 journal is improved by 0.30mm/m on the basis of the installation standard for compensation.
TABLE 1 high and medium voltage rotor loft value (mm/m)
(3) The unit has 4 high governing nozzle groups, and the top is left 3 right 4, and the below is left 1 right 2, and the direction of the circumferential airflow direction is as shown in figure 2 from the steam turbine to the generator. The original valve sequence of the sequential valve operation is (3 + 4) → 1 → 2, and when the valve adjustment is synchronously opened under low load (3 + 4), the resultant force of the vector superposition of the air flow force is rightward along the horizontal direction, so that the center of the rotor deviates to the right side, and the air flow excitation is easily induced. When the No. 1 regulating door of the third sequence is fully opened under high load, the rotor is subjected to airflow force towards the upper left, the floating quantity of the rotor in the direction reaches the maximum value, and the dynamic stiffness of the support system is reduced due to the increase of the thickness of an oil film, so that the vibration value is amplified.
According to the vibration characteristic analysis of the unit, the diagonal air inlet mode is adopted, the valve is synchronously opened at low load (2 + 3), the vector sum of airflow force can be mutually offset in theory, and the horizontal offset of the rotor is reduced to the maximum extent. The third sequence of opening gates under high load is changed into No. 4 gates under the right, so that the stress condition of the rotor under high load can be improved. Therefore, the sequence valve sequence of the unit is changed to (2 + 3) → 4 → 1 before the dynamic balance test.
(4) Two end faces of the high-medium pressure rotor of the unit are respectively drilled with 24 screw holes, and a balance hole is drilled on the plane of the coupling with the long shaft connected in the front box. Determining a dynamic balance scheme through spectrum analysis and mode homonymy and inverse decomposition as follows: applying 1300 grams & lt 100 DEG of counterweight at the front end of the high and medium pressure rotor, applying 1300 grams & lt 100 DEG of counterweight at the rear end, and simultaneously applying 1100 grams & lt 280 DEG of counterweight on a coupling between the high and medium pressure rotor and the extension shaft. And starting again after the dynamic balance test, reducing the 1-shaft vibration speed of the high-and-medium-pressure rotor from the original 200 mu m to 100 mu m after passing through the critical vibration value, and ensuring that the maximum value of the 1-shaft vibration value is not more than 80 mu m in the fixed speed 3000r/min and high load carrying process. The requirement of safe and stable operation of the unit is met.
The above examples illustrate that, by applying the dynamic balance method, the problem that the vibration of the high-medium pressure rotor of the 660MW steam turbine generator unit exceeds the standard is quickly and effectively solved by applying balance weights to the balance holes at the two ends of the high-medium pressure rotor and the balance hole of the extension shaft coupler at the same time.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. A dynamic balance method for eliminating unstable vibration of a shaft system is characterized by comprising the following steps:
step l: carrying out maintenance adjustment on front and rear bearings of a high-medium pressure rotor of a high-capacity steam turbine, wherein the top clearance of the bearings is the lower limit of an installation standard value;
step 2: testing the journal lift of the high and medium pressure rotor under the condition of not dismantling a coupler, comparing the journal lift with maintenance records during installation, and adjusting a corresponding value to compensate the journal lift value on the basis of an installation standard value according to the variable quantity value of the journal lift during reassembly and the metal temperature difference of a front bearing and a rear bearing of the high and medium pressure rotor in the running state;
and 3, step 3: the valve sequence of the sequence valve is changed into a diagonal air inlet mode, and the offset of the rotor in the horizontal direction is reduced; when the direction from the steam turbine to the generator and the rotation direction of the rotor is clockwise, the regulating gates opened in the third sequence at high load are changed into the regulating gates at the right lower part of the stress direction of the rotor;
and 4, step 4: carrying out spectrum analysis on shaft vibration of front and rear bearing measuring points of the high and medium pressure rotor to find out a power frequency vibration component in the shaft vibration; carrying out homodromous vector and reverse vector decomposition on the vibration modes of the high and medium pressure rotors;
if the first-order vibration mode is dominant, applying a group of counterweights with the same phase in the balancing holes at the two ends of the span of the high and medium pressure rotor, and applying a group of counterweights with the phase opposite to that of the cross-internal counterweights in the balancing holes of the long shaft coupling at the front end of the high and medium pressure rotor;
if the second-order mode is mainly the mode, a group of counterweights with opposite phases are applied to the balance holes at the two ends of the span of the high-medium pressure rotor, and a group of counterweights with the same phase as the counterweights at the front end of the span of the high-medium pressure rotor are applied to the balance holes at the front end of the high-medium pressure rotor and the long shaft coupling.
2. The dynamic balance method for eliminating unstable vibration of shafting according to claim 1, wherein the contact area of the tile sleeper iron in step 1 is controlled to be more than 75% and uniformly distributed.
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| CN202211075848.1A CN115541114A (en) | 2022-09-05 | 2022-09-05 | Dynamic balance method for eliminating unstable vibration of shafting |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116379011A (en) * | 2023-03-29 | 2023-07-04 | 华能山东发电有限公司烟台发电厂 | Fan spindle installation method and device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116379011A (en) * | 2023-03-29 | 2023-07-04 | 华能山东发电有限公司烟台发电厂 | Fan spindle installation method and device |
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