CN108952837B - Device and method for monitoring cat claw load change in process of starting steam turbine to be in hot state - Google Patents
Device and method for monitoring cat claw load change in process of starting steam turbine to be in hot state Download PDFInfo
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- CN108952837B CN108952837B CN201810649848.5A CN201810649848A CN108952837B CN 108952837 B CN108952837 B CN 108952837B CN 201810649848 A CN201810649848 A CN 201810649848A CN 108952837 B CN108952837 B CN 108952837B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
- F01D21/003—Arrangements for testing or measuring
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
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- Control Of Turbines (AREA)
Abstract
The invention discloses a device and a method for monitoring cat-claw load change in the process of starting a steam turbine to a thermal state. According to the invention, a micro-strain technology is utilized, strain gauges are arranged on the side surfaces of the cat claws of the cylinder and above the gaskets to measure the strain of the cat claws, and the actual load is calculated.
Description
Technical Field
The invention relates to monitoring of load change of a steam turbine cat-paw, in particular to a device and a method for monitoring the load change of the cat-paw in the process of starting a steam turbine to a hot state.
Background
The turbo generator set is the core equipment of the thermal power plant. The quality of the cylinder mounting has a significant effect on the operating performance of the unit. In general, the high-pressure cylinder and the intermediate-pressure cylinder are supported on bearing blocks at two ends through four front, rear, left and right cat claws. In order to ensure that the gravity of the cylinder is reasonably distributed to each cat claw, the cylinder is made to be level and stable, and is freely unfolded and unfolded on each bearing surface, so that the cylinder can be freely stretched and retracted in operation, and the load distribution is required when the cylinder is installed. If the load distribution is unreasonable, and the load of a certain cat claw is too heavy, the consequences of unsmooth expansion, uneven deformation, foundation settlement and the like of the cylinder can be caused, and then the unit generates larger vibration. Meanwhile, the rotor can generate additional load to the cat's claws on one side when rotating; in the process from a cold state to a hot state, factors such as expansion of a unit and the like also cause the load of the cat-paw to change, and the cat-paw load is possibly uneven in hot-state operation, so that large vibration is generated.
The common methods for distributing the load of the cylinder at present mainly comprise a dynamometer method, a cat claw arc dropping method and the like. The method of the dynamometer is that a special dynamometer is inserted into a bolt hole special for the cat-paw, the factory load test curve of the dynamometer is checked through a spring compression value indicated by a dial indicator on the upper portion of the dynamometer, and then the thickness of a gasket is adjusted according to the load value of each cat-paw, so that the load difference of a symmetrical point is within an allowable range. The cat-claw vertical arc rule is that the thickness of the gasket at the lower part of each cat claw is adjusted by comparing the natural sagging amount (vertical arc) of the supporting cat claws at the left-right symmetrical positions under the condition of no cat claw gasket support, so that the difference of the cat claw vertical arc at each symmetrical point is in an allowable range. Both methods are only suitable for assigning cylinder load at installation and cannot monitor the changing course of the cat's paw load during operation.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a device and a method for monitoring the change of the cat-paw load in the process of starting a steam turbine to a hot state, and the device and the method can be used for solving the problem that the change process of the cat-paw load in the operation process cannot be monitored at present.
The technical scheme is as follows: the device for monitoring the cat-claw load change in the process that the steam turbine is started to be in the thermal state comprises strain gauges, a wireless transmitting device and a wireless receiving device, wherein the strain gauges are symmetrically arranged on the side faces of the cat claws, the strain gauges are connected to a balance bridge circuit in the wireless transmitting device, and the wireless transmitting device is in wireless signal connection with the wireless receiving device.
For convenience of pasting, the strain gauge is pasted on the cat-paw pad through an adhesive.
In order to eliminate the influence of temperature on strain, the strain gauge is connected into a full-bridge Poisson ratio circuit built in the wireless transmitting device.
The invention relates to a monitoring method of a device for monitoring the change of cat claw load in the process of starting a steam turbine to a hot state, which comprises the following steps:
(1) determining and marking the specific position of the strain gauge to be adhered on the cat-paw, cleaning the surface of the cat-paw, dipping a cotton ball in alcohol to wipe the part to be adhered, symmetrically adhering the strain gauges to the side gaskets of the cat-paw, and horizontally adhering one strain gauge to the side gasket of the cat-paw on the same side and vertically adhering the other strain gauge to the side gasket of the cat-paw;
(2) setting the strain value of the strain gauge to zero under the condition that the cat's claw does not bear load;
(3) enabling each cat claw to bear the load of a cylinder, recording the initial value of each cat claw in a strain pre-installation state, and recording the strain value of each cat claw as epsilonA、εB、εC、εDSubstituting the strain value into formula FCalculate each paw load F as AE εA、FB、FC、FDWherein F is the cat's paw load, A is the pad contact area, E is the elastic modulus, and epsilon is the strain value;
(4) comparing the strain values at the symmetrical cat claws, and judging whether the loads of the cat claws meet the requirements: the difference in load between the two paws on the same side of the base is no more than 5% of their average load, and wherein the load of the paws subjected to the additional load when the cylinder is in motion is less;
(5) according to the judgment result, the cat claws at one end with larger strain difference are adjusted by adding and subtracting the temporary gaskets, and then the cat claws at the other end are adjusted, so that each cat claw meets the requirement of the step (4);
(6) measuring the total thickness of the temporary gasket, processing a formal cat-claw gasket, and installing the formal gasket to finish the load distribution of the cylinder;
(7) after the unit is started, the wireless equipment is utilized to continuously acquire dynamic strain of the cat-paw, and a strain mean value is obtained through data processing, so that the load of the cat-paw is calculated, and the change of the load of the cat-paw in the process from starting to the hot state of the unit is monitored.
The rust oil stain on the side face of the cat claw is cleaned, the surface of the position where the strain gauge is adhered is sanded by using gauze paper, and then the position to be adhered is wiped by using absorbent cotton balls dipped with alcohol until no black stain appears on the cotton balls.
Has the advantages that: the invention utilizes the micro-strain technology, and measures the actual load of the cat-paw by arranging the strain gauge on the cat-paw of the steam turbine cylinder, thereby providing a basis for the load distribution of the cylinder. The gravity of the cylinder is reasonably distributed to each bearing surface finally by adjusting the thickness of the gasket, so that irregular deformation and vibration of the cylinder are reduced, and the unit is ensured to operate safely and stably. The invention has the advantage that the precision of load measurement is higher due to the linear characteristic of excellent strain, so that the load distribution is more reasonable. Meanwhile, after the strain gauges are arranged, all the cat-paw loads can be directly obtained, repeated measurement of all the cat-paw loads is not needed, and later-stage operation is simpler and more convenient. The method can monitor the change process of the cat-paw load in the process from starting to hot state of the unit, thereby providing a basis for the load redistribution of the cylinder in the later overhaul process and ensuring that the load distribution of the cylinder is more reasonable.
Drawings
FIG. 1 is a schematic illustration of a method of monitoring a change in a steam turbine catclaw load in accordance with the present invention;
FIG. 2 is a schematic view of the cylinder and cat's claw support of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in figure 1, the device that the cat claw load of monitoring steam turbine start-up to hot in-process changes, including foil gage 4, wireless transmitting device 5 and wireless receiving device 6, foil gage 4 symmetry sets up on each cat claw 1 side gasket 2, and built-in full-bridge poisson's ratio circuit in the foil gage 4 access wireless transmitting device 5, wireless transmitting device 5 and the wireless receiving device 6 wireless signal connection, foil gage 4 pastes on cat claw gasket 2 through the adhesive.
When the device is adopted to monitor the load change of the cat claws in the process from starting to hot state of the steam turbine, firstly, a group of strain gauges are arranged at the two side surfaces of each cat claw and the symmetrical positions above the gasket, and the working procedures of polishing measuring point positions, wiping with alcohol, pasting the strain gauges and the like are included, and each group of strain gauges are arranged at the same position of each cat claw. Then, 4 resistance strain gages of each group are connected into a full-bridge Poisson ratio circuit, and strain signals are transmitted to wireless receiving equipment through wireless transmission equipment so as to read and store strain signal values. And (4) enabling each cat claw to naturally droop in sequence, wherein the cat claws do not bear load, and the strain value is set to be zero. Each paw is then subjected to cylinder load, at which time the strain value of the strain gage on each paw will change. The excellent linearity characteristics of the strain gage reflect well this linear relationship between strain value and cat's paw load, i.e., F ═ AE ε, F is the cat's paw load, A is the pad contact area, E is the modulus of elasticity, and ε is the strain value. The strain value of the strain gauge on each cat claw is read, and the load of each cat claw can be obtained through the calculation. The design of the cat's claw load generally requires that the load differential across the cylinder centerline at laterally symmetrical locations should be no more than 5% of the average load on either side. Therefore, the load difference calculated by the symmetrical cat claws does not exceed 5% of the average value of the two sides only by adjusting the gaskets at the lower parts of the cat claws at the symmetrical positions. When the gasket is added or subtracted in the adjusting process, the two symmetrical cat claws are adjusted one by one, and the influence on the center of the hollow nest is reduced. And after the strain difference value meets the standard, the cat paw load is also distributed to be qualified. And measuring the thickness of each temporary gasket by using an external micrometer, adding to obtain the total thickness value of each cat's claw gasket, and processing and installing a formal gasket to finish the load distribution work of the cylinder in the installation stage. After the unit starts, still can gather cat claw dynamic load through wireless device. The cat claw load change of the monitoring unit in the process from starting to the hot state can provide a basis for the load redistribution of the cylinder during later maintenance, so that the load distribution of the cylinder is more reasonable.
As shown in fig. 2, the cylinder 8 is supported on the front and rear bearing blocks 9 by four front, rear, left and right cats claws 7, the number of each cat claw is A, B, C, D, and the monitoring method is implemented according to the following steps:
(1) a set of strain gauges is symmetrically disposed above each cat-paw side pad: firstly, the specific position of the adhered strain gauge is determined and marked, and the position symmetry of the patches on the two sides of the cat's claw is ensured. The two strain gauges on one side are arranged vertically and horizontally, and the other side corresponds to the strain gauges. And cleaning rusty scale, oil stain and the like on the side surface of the cat claw A, and sanding the surface of the adhered position by using gauze paper. Then, the part to be pasted is wiped by using absorbent cotton balls dipped with alcohol until no black stains appear on the cotton balls. After cleaning, uniformly coating the adhesive on the patch, and sticking the strain gauge according to the marked position. And then, the resistance strain gauge is connected to the wireless transmitting device with the built-in bridge circuit, and the other three cats of the BCD also perform the same operation.
(2) Set the strain value of the strain gage to zero when the cat's claw is not under load: and jacking the cat claw A by using a jack, taking down the temporary gasket, and putting down the jack to enable the cat claw to hang down freely. And the strain values of the two symmetrical strain gauges are set to be zero through the control of the wireless receiving device. The temporary spacer is then reinstalled, returning the a cat's paw to the pre-installed condition. The same operation was done for the remaining three BCD paws.
(3) Record the initial value of each cat's paw in the pre-installation state: after step (2) is completed, each strain will change under load on the cat's paw. Record strain value of each cat paw of ABCD as epsilonA、εB、εC、εD。
(4) Calculating and comparing strain values at symmetrical cat claws, and judging whether the load of each cat claw meets the standard: calculating each paw load F by the formula F ═ AE epsilonA、FB、FC、FD. According to the standard, the difference in load between the A and B paws should not exceed 5% of their average load, i.e. the load should be equal to
At the same time, when the steam turbine runs, additional load is generated on the cat paw B, so that F is ensuredA＞FB. C and D paws were also checked against the same criteria.
(5) The temporary shim was adjusted to make the cat's paw load tend to be reasonable: first, adjustment should be made for the end with larger strain difference. Assume A, B cat paw strain values differ more, and FA＞FBThe pad should be added on the side A and the same thickness on the side B. The adjustment is repeated until the standard is met. Because the cylinder supported by the cat's claw is of a statically determinate structure, it is generally adjusted for one end. If C, D cat-paw load has not met the criteria, it can be fine-tuned.
(6) Mounting a formal gasket to finish the load distribution work of the cylinder: and measuring the thickness of each gasket by using an external micrometer, finally adding to obtain the total thickness value of each cat claw, processing formal cat claw gaskets, and installing the formal gaskets.
(7) Monitoring the load change of the cat's claws in the process of starting the unit to a hot state: after the unit starts, utilize wireless device to continue to gather cat claw dynamic strain. And setting a higher sampling rate to adapt to the unit frequency, and obtaining a strain mean value through data processing so as to calculate the cat-paw load. Therefore, the load change of the cat's claws of the machine set in the process from starting to the hot state is monitored, a basis is provided for the load redistribution of the cylinder in the later maintenance process, and the load distribution of the cylinder is more reasonable.
Claims (4)
1. A method for monitoring a device for monitoring the change of the load of a cat's claw in the process of starting a steam turbine to a hot state is characterized by comprising the following steps:
(1) the device for monitoring the cat-claw load change in the process that the steam turbine is started to be in a hot state comprises strain gauges (4), wireless transmitting devices (5) and wireless receiving devices (6), wherein the strain gauges (4) are symmetrically arranged on the side faces of the cat claws (1), the strain gauges (4) are connected to a balance bridge circuit in the wireless transmitting devices (5), and the wireless transmitting devices (5) are in wireless signal connection with the wireless receiving devices (6);
(2) determining and marking the specific position of the strain gauge to be adhered on the cat-paw, cleaning the surface of the cat-paw, dipping a cotton ball in alcohol to wipe the part to be adhered, symmetrically adhering the strain gauges to the side gaskets of the cat-paw, and horizontally adhering one strain gauge to the side gasket of the cat-paw on the same side and vertically adhering the other strain gauge to the side gasket of the cat-paw;
(3) setting the strain value of the strain gauge to zero under the condition that the cat's claw does not bear load;
(4) enabling each cat claw to bear the load of a cylinder, recording the initial value of each cat claw in a strain pre-installation state, and recording the strain value of each cat claw as epsilonA、εB、εC、εDAnd substituting the strain value into a formula F ═ AE epsilon to calculate each cat-paw load FA、FB、FC、FDWherein F is the cat's paw load, A is the pad contact area, E is the elastic modulus, and epsilon is the strain value;
(5) comparing the strain values at the symmetrical cat claws, and judging whether the loads of the cat claws meet the requirements: the load difference of two claws on the same bearing block is not more than 5% of the average load, and the claw load bearing the additional load when the cylinder moves is smaller;
(6) according to the judgment result, the cat claws at one end with larger strain difference are adjusted by adding and subtracting the temporary gaskets, and then the cat claws at the other end are adjusted, so that each cat claw meets the requirement of the step (5);
(7) measuring the total thickness of the temporary gasket, processing a formal cat-claw gasket, and installing the formal gasket to finish the load distribution of the cylinder;
(8) after the unit is started, the wireless equipment is utilized to continuously acquire dynamic strain of the cat-paw, and a strain mean value is obtained through data processing, so that the load of the cat-paw is calculated, and the change of the load of the cat-paw in the process from starting to the hot state of the unit is monitored.
2. The method for monitoring the change in the load of the cat's paws during the startup of the steam turbine to the hot state according to claim 1, wherein the strain gauge (4) is adhered to the cat's paw pad (2) by an adhesive in the step (1).
3. The method for monitoring the device for monitoring the cat-claw load change in the starting process of the steam turbine to the thermal state according to claim 1, wherein the strain gauge (4) in the step (1) is connected to a full-bridge Poisson ratio circuit built in the wireless transmitting device (5).
4. The method for monitoring the device for monitoring the load change of the cat's claws during the startup to the hot state of the steam turbine as claimed in claim 1, wherein in the step (2), the rust oil stain on the side surfaces of the cat's claws is cleaned, the surface of the position where the strain gauge is adhered is sanded by using gauze paper, and then the position to be adhered is wiped by using absorbent cotton balls dipped with alcohol until no black stain appears on the cotton balls.
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| CN113464214B (en) * | 2021-05-25 | 2022-10-14 | 内蒙古蒙达发电有限责任公司 | Steam turbine cylinder load measuring device |
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| CZ306833B6 (en) * | 2012-12-20 | 2017-08-02 | Doosan Ĺ koda Power s.r.o. | A method of detecting and locating a partial rotor-stator contact during turbine operation |
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