Diagnosis and Prevention of Friction Vibration Faults in Turbogenerator Sets

1 Diagnosis and Prevention of Friction Vibration Faults of Turbogenerators China Power International Co., Ltd. North; 100005 Cao Yan North China Electric Power Research Institute Co., Ltd. North Ke 1451 Xu Zhijing The vibration and the large shaft bending accident caused by it have occurred. This paper introduces the thermal bending effect caused by friction. The rotational speed and critical speed of the rotor are in four different situations. At the same time, different phenomena and consequences of frictional vibrations occurred; different extremes of minor and severe frictional faults; diagnoses and examples of frictional vibration failures. Finally, it was pointed out how to prevent frictional vibrations, that is, to change overhaul and operation of equipment management structures. The friction and vibration between the dynamic and static parts should be taken into consideration for the friction and vibration of 1 key division, critical speed, and large-axis test turbine generators, especially turbines, due to large changes in the elevation of their structures, as well as the displacement and deformation of the cylinder's expansion. Friction and vibration failures have been repeated. Therefore, the large-axis bending accidents of steam turbines caused a large number of economic losses to the society and the power companies themselves. Therefore, the diagnosis and prevention of friction and vibration faults of turbo-generator units is increasingly becoming an issue that people pay attention to. In the case of turbo-generator sets, the most significant influence of friction due to friction is due to the thermal bending effect of the dynamic and static parts, and the degree of rubbing of the transfer surface along each point in the circumferential direction is different. The temperature on the radial side is still on the light-friction side, resulting in a new unbalanced force acting on the rotor in the radial section of the rotor and causing vibration. This is the thermal bending effect of friction known from vibration theory. When the rotor rotates, due to centrifugal force, the eccentricity that generates the centrifugal force is the key position, and this phase difference or high point lags behind the critical lag angle. D can be determined by the formula. k working violation degree k critical angle violation can be discussed by Equation 1. With the angular velocity of the work, when the rotor is stationary, ie, when the numerator of formula 1 is zero at this time, Wei 0 is at a critical point in the rotation speed of the small factory, and it is immediately changed from the formula to the difference between the shift and the shift. That is, the closer to 90 Ding closer to 90, so when the rotor is running below the critical speed, the direction of the difference between the azimuth and the eccentricity 6 of the direction of the eccentricity 6 between the direction of the centrifugal force caused by the small difference between 1 is small Gong 90 convex operation If the speed is far from the critical speed, it can be regarded as approximately the 1st and 1st, and if the part of the turbine is stationary, it will easily lead to a big shaft bending accident.

The blade can be seen by formula 1 when the running speed is equal to the critical speed port, because the denominator is zero, so 1 90! At this time, the dynamic deflection includes the direction of the vibration caused by it lagging behind the eccentricity of the eccentric force 90; 4 When the rotation speed is much larger than the temporary deviation, that is, by the formula 1 can be seen 18 negative and close to Zero, ie, D is close to 18 E. At this moment, if the rotor has elastic heat bending caused by friction, the dynamic deflection is reduced and the friction is removed. According to the formula above, there are 4 different types of turbine rotor operating speed and critical speed. In this case, the relationship between the azimuth of the eccentricity of the rotor and the azimuth which causes less dynamic burn is important for preventing the large shaft bending accident of the steam turbine. These large turbine units are after major repair or hot shutdown. 1 fire shaft bending accident. The vast majority of these are due to improper handling of frictional vibrations, which can be summarized as follows: When the operating speed is low, the critical distance is far from the critical speed, the phase difference is close to zero, or the sharp angle is the critical speed. Bits and dices are equal to the enthalpy condensates at 晷孺90; in the regions above the critical rpm, the phase difference is an obtuse angle, and when the operating speed is much higher than the critical speed, it can reach a level close to 180 degrees. During steam turbine start-up, from low speed to high speed. 41 through the critical speed, dynamic deflection and eccentricity between the two 荇 phase difference between the D in turn by an acute angle 9, blunt 180 changes, from the same phase into a reverse phase process.

The following is combined with the rubbing vibration and the concept is described in detail.

The frictional vibration occurs when the critical speed is lower than the centrifugal force. The centrifugal force increases with the square of the deviation. If the dynamic deflection caused by the poor rotor dynamic balance or the original thermal bending existing before the start of the unit exceeds the turbine's reserve shift, When the radial clearance in a certain direction disappears, rubbing will occur between the steam seals or between the chocks, and the rotor bomo gradually accumulates heat according to the parts, so that the heat is deformed by the pupa. This is because the phase difference is close to the acute angle, ie, The azimuth caused by thermal deformation and the original eccentricity of the rotor are basically caused by each other. The eccentricity causes the thermal deformation caused by the friction and friction of the rotor to increase the eccentricity. Such a vicious cycle will cause the dynamic and static part of the friction to increase in a short period of time, the vibration condition of the unit will deteriorate sharply, and finally a permanent curvature of the rotor will be formed. Most of the large-axis bending accidents caused by frictional vibrations occur below the critical speed. The reason for this is the frictional vibration that occurs at the critical speed. In general, the rotor's dynamic deflection at the critical speed is several times the operating speed. When the dynamic deflection of the rotor is especially for the newly installed or overhauled unit, when passing the critical speed. It is easy to happen to the dynamic and static parts. Therefore, at the start of the crankcase 1, it should pass through the critical speed of each order of the shaft system at a faster speed to avoid staying at the critical speed of the rotor. At the critical rotation speed, the dynamic burn of the rotor lags behind the eccentricity 90 of the rotor. Now, 1 is used to indicate that the dynamic deflection caused by the initial eccentric force of the friction process at this time 5 lags behind 9 戊 If friction occurs, it is inevitable. Starting from a good point in the 5 direction and generating thermal deformation at a good point, a new eccentricity is formed in the direction of 10,000. The eccentricity 4 after the two eccentricities are synthesized. 1 90, it is the friction point that has shifted from 5 to the direction. In this case, the new eccentricity is formed after five thermal deformations due to friction. Thus, it can be found that the vibration vector rotates on the rotating side of the reverse turbine. This phenomenon is exactly one characteristic of frictional vibration. This feature constitutes the whole-peripheral friction of the rotor, which means that the rotor bending due to friction at the critical speed is in the general case a temporary thermal bending. Therefore, with a quick mention, the speed through the critical speed of the conversion, without deduction. Transmitting will be less perpetually well-behaved 1 The friction frequency 4 at this moment's critical speed is within this speed range. The phase difference is an obtuse angle. And the farther away from the critical rotational speed of the transporter to the rotor, the closer to 18, if frictional vibration occurs, a very favorable situation occurs. As the dynamic burning degree direction and the eccentricity direction are close to each other, the frictional heat is generated. The deformation has a tendency to counteract the original unevenness, or the friction-induced deformation has a tendency to retreat from friction and below the critical rotational speed, the situation due to the heat caused by the friction finger aggravates the friction. In the moving part, micro friction occurs, and even the wiper spark pool appears at the end of the rotor at the end of the rotor, and the rotation speed is rapidly increased to the working speed, which is 1; the permanent cycle of the Huishan will also be increased due to shaft vibration. The characteristics of the friction of the mantle The turbine rotor and the generator of the large-scale turbo-generator set in modern times are all flexible rotors, and the phase difference between the rotational speed and the eccentricity of the rotational speed 7 is an obtuse angle. At this time, if the original unbalance of the rotor is small, it is much smaller than the frictional unbalanced component. The characteristics of the friction of the friction are the rotation vector of the vibration vector and the periodic variation of the amplitude over time. Measure the shaft vibration vector of a 325 river unit in 21! Rotate 360 ​​inside! When the vibration vector is at a specific phase angle, the thermal eccentricity caused by friction and the original mass eccentricity of the rotor coincide with each other, and the amplitude is the largest; and at the phase difference of about 180 degrees, the amplitude is the minimum and the motion and static partial friction occurs at the working speed because the two directions are opposite.撺 撺 撺 撺 撺 若 若 若 若 若 若 若 若 若 若 若 原始 原始 原始 原始 原始 原始 原始 原始 原始 原始 原始 原始 原始 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若 若The unbalanced component of the rotation. The new unbalanced size and phase of the synthesis are not as good as the rabbits. The above three typical situations can be used for 22 inhabitants.

For the original is not, the balance; 51 decay is not measured due to the friction generated by the friction; 004 is the amount of the body and the body of the body into the amount of 4 respectively.

With some nonlinear effects, there may also be a small number of frequency-division and frequency-doubling sums. The amplitude and phase of the vibration of one-frequency component friction have a fluctuating characteristic. For a slight frictional vibration that occurs at or above the critical rotational speed, the vibration phase significantly reverses the rotor. Rotation in the direction of rotation, even at the beginning of 36 weeks; the amplitude of the amplitude changes periodically with time. When the friction is severe, the vibration amplitude and phase no longer fluctuate.

The vibration phase is basically unchanged, and the amplitude will increase sharply. The amplitude of vibration will be divergent. When the speed is lower than the critical speed, the vibration will be higher than normal. When the speed increases, friction vibration will occur. After the friction vibration occurs, the machine will stop to the state of the disc brake and immediately check the rotor's shaking pit. It is much larger than the normal value, which is generally 10 levels. If it is an elastic thermal bending, the normal sway of the rotor can be restored after the rolling time.

3 Examples of frictional vibration and its fall If the dynamic and static friction at working speed is strictly to a certain extent, the deformation caused by the local thermal expansion of the friction part is much greater than the dynamic deflection due to the mass eccentricity caused by the original bending of the rotor. This deformation is much larger than the value of the dynamic and static partial clearance value. When severe local friction occurs, the newly generated dynamic burning degree has only a tendency to avoid friction, but the original friction point is still not separated, so the vibration phase at this time is basically unchanged. The amplitude gradually increases, showing a divergent trend. After flashing this type of Capricorn vibration occurs at the rotor brake, the + must be over-concerned about the permanent bending of the rotor. Taiwan 100 Hejia turbine in the starting process of friction and vibration, after the goods according to the most serious wear parts of the wear and tear, calculation, fault, the friction part of the static and dynamic part of the total deformation of up to 4.3. In the test station 3004 boundary unit, during the test-to-near-to-space-to-electrical test, friction between the low-pressure steam seal and the bearing housing at the oil stop caused friction and vibration, the enthalpy amplitude was divergence and large, and the reverse rotation change did not exceed 20 = only then Amplitude, large to a fixed limit, ie, stop-and-stop measures. 2 Characteristics of frictional vibrations. Accompanying the above comprehensive analysis of the frictional vibrations generated under different conditions, the following characteristics of dynamic and static frictional faults can be summarized for turbogenerators. The diagnosis of frictional vibrations is crucial.

3.1 Frictional Vibration Occurring below the Critical Rotation Speed ​​of the Rotor One Unit of the Two-rank Steam 200 River Unit During the normal shutdown inspection, the cylinder temperature slipped to about 35, and the idle movement of the second bearing was not smooth. When the middle cylinder contracts, the front end of the bearing seat is lifted, and the lower clearance of the lower front cylinder seal of the jade cylinder causes frictional vibration. At about 17007 below the critical speed of the high-pressure rotor, the on-line vibration monitor 300 and 0% 2,000 have shown that the shaft vibration is abnormal, but at that time it was unable to cause the operator to pay attention to the unit has not yet stopped, and failed to check the rotor under the condition of the crank. The degree of shaking, that is, rapid steam injection, the unit speed is maintained at around 500. Later, when the operator found that the speed was 1 攘 ready to open a large throttle valve, the rotor had a flash of friction torque is too large and still. The operation of the electric disk unit and the subsequent process of the test and the measurement of the rotor sloshing value confirmed that the high pressure rotor had undergone a permanent bending and demolition inspection. The permanent bending of the high pressure rotor front shaft seal reached a record high of 1.8.

A two-cylinder double-cylinder 300-height turbine unit has just been put into operation for about half a year. During the first hot start process, the steam temperature ratio of the steam turbine high pressure main valve and the reheat main steam valve is higher than that of the boiler due The steam temperature is about 35, and 25, which is about 3300. After the stoppage of the 3300 operation, the degree of rotor slewing is checked and turns from +, 3 to 0.03, confirming that the high and medium pressure rotors have been permanently bent. For the demolition inspection, the permanent bending centroid value of the rotor at the shaft seal between high and medium pressure is 61. From the above example, it can be seen that the friction vibration 1 at low rotation speed will generate a new unbalanced force due to thermal bending, so the vibration, Li Li, Le Lizi, Li Lifeng, 9, Li Dai, must make a straight-axis treatment. This more intuitively confirms the critical spin speed below the severity of the tribo-vibration 3.2. The frictional vibration that occurs at operating speed is due to the large turbo-generator set. Turns are all flammable rotors. Therefore, what happens at this time is higher than the quasi-critical speed. Vibration can be seen from the examples listed above. The slight friction and vibration at working speed is not harmful. Repeatedly several times of stopping and stopping process can eliminate the working speed. Under severe friction and vibration, maintenance measures must be taken before it can be completely resolved. The frictional vibration of a 300 river unit set out in the previous trial during trial operation was revealed. After the inspection of the low pressure cylinder, the radial gap of the local seal disappeared because of the cylinder displacement, and the dynamic and static parts were severely rubbed; The baffle has grinded the shaft surface into a deep groove. As an interim measure, the manufacturer increased the radial clearance of the diaphragm seal to 1.21.8 radius, improved the oil, and assembled the structure, so that the frictional vibration was eliminated.

4 Prevention of Friction and Vibration Failure The above detailed discussion of the example of the vibration failure caused by friction and vibration of a steam turbine generator set seems to be more important than how to prevent frictional vibrations, ie what measures should be taken in the equipment management structure to avoid overhaul and operation, etc. In order to prevent the occurrence of frictional vibration, we must first analyze the weak points of the unit structure 1, mining, and effective structural improvements along the Shi and maintenance measures to solve, mainly in the following aspects, 4.1 steam seal structure and material modern large-scale The steam turbine diaphragm seal and the end shaft seal adopt elastic seal. The material of the steam seal teeth is 1 in the high temperature section, or 5, and the low temperature section is called 8 yellow 14. According to the conclusion of the simulation test of a certain department. For a redeployment of pearlite materials, if the elastic force of the bomb is only about 504, the amount of heat applied to the shaft when the seal teeth and the shaft friction are not large, and the temperature is about 200300. In the rated load, the height of the steam seal of the high 1 card steam seal inside and outside the steam pressure difference is affected by the small steam seal teeth and the shaft is cut out of the groove is relatively deep to the 68 brass, because of its low melting point of 93, the hardness is not high 55. When the seal teeth and the shaft are rubbed, the teeth are rapidly worn and adhered to the shaft surface to act as a lubricant, so that the wear of the shaft is greatly reduced. If a spring force of 50,500 is applied to the arc of each seal, the maximum temperature reached by heating the shaft due to friction is only the conclusion of the above test. The existing steam seal structure shall eliminate the steam force acting on the back of the arc block; if the back of the arc block uses a leaf spring, it is recommended to use the division division yellow to retreat the arc block evenly with a secondary spring force; the gap should be increased to 2.51. The above steam seal arc neck wide 1 oil gap should be increased to 0.5 瞧 temperature range of steam seal tooth material proposed to 015 river, ferritic material, the hardness of this material is lower secretion of 86. is 89.8, while in the friction After heating will not be hardened 950, after the hardness of the oil quencher book 55.557.0 steam seal radial clearance can be as small as 0 381 without damage to the shaft seal applied to the low temperature section of the tooth material including shaft end seal recommended all The use of Sun lead diesel 4.2 bearing box and cylinder expansion bearing box movement is not easy to make the cylinder expansion or contraction blocked, the cylinder deformation or offset will lead to a radial gap in the flow through the turbine part, and cause static and dynamic part of the friction for this kind of question The unit should be improved in the following aspects of the structure to improve the lubrication between the bottom of the bearing box and the platen to reduce the friction when moving. The current effective method is to use a zero-manufactured alloy slider or a graphite block embedded in a steel or praying iron slider to improve the structure of the push-pull device. The trick is to shift the thrust point. This reduces the turning moment when the bearing box is prevented from moving and causes the cat's claws to be no longer a load bearing point for pushing and pulling.

Add auxiliary support on the cylinder, reduce the pressure on the bearing box to reduce the shaft seal leakage, to prevent the sliding of the bottom of the bearing box. Corrosion can be considered to change the material of the longitudinal file, or surface hardening treatment, so that the high temperature oxidation While the card flow 4.3 test dynamic balance overhaul to test the dynamic balance of the rotor, focusing on reducing the critical speed through the shaft vibration water should be done at various speeds and loads, the unit's vibration conditions are good, 4.4 improved insulation materials used Good performance cylinder insulation material, such as aluminum silicate fiber felt. And improve the insulation construction technology to ensure that the insulation material is tightly attached to the cylinder, and no phenomena such as loosening of holes or faults will occur. 4.5 Guaranteed Installation Accuracy Ensure that each rotor's bending value is the value of the coupling's sloshing value, especially after the wheel is connected. The qualified value of 4.6 to adjust the clearance of the gap portion of the gap turbine should meet the standard requirements. Adjustment and measurement accuracy, and reduce the standard deviation of 纟 1 standard deviation should be configured in different directions on the cross-section of the seal gap in all directions High and medium pressure rotor If the use of fulcrum support. The influence of the static deflection of the rotor on the radial clearance of the throughflow section after connecting the wheels is to be considered.

4.7 fine-tuning rotor center strict quality standards strictly in accordance with the gun repair process requirements for the rotor heart line conditions, determine the thermal state when the bearing height change, when the unit cold state adjustment should be the interest rate of the bearing tight Liegeiwujin et al.

4.8 oil block bearing housing oil block should be changed to facilitate the installation and adjustment of the structure.

The oil clearance gap should meet the standard oil stop material and tip shape should meet the paper requirements 4.9 Slip system overhaul should be carefully cleaned Check the sliding pin system to check the positioning of the inner and outer cylinders and guide parts to eliminate the deformation of the jam and other faults to ensure Part of the through-flow gap is not changed. 4.10 Complete monitoring instrument The on-line monitor for turbine generator vibrations includes the vibration measurement and shaft vibration measurement of each main bearing, and the vibration analysis tube of the subsequent vibration analysis system. The system has less data to show the trend of the analysis of the spectrum analysis of the Porter limit reporting and printing system and other functions in the cylinder cat claws, install the cylinder lateral expansion finger to monitor the cylinder expansion on the left and right side is Qiao 4 in the steam turbine Each axle bearing can be equipped with a shaft-mounted axle axle vibration measuring device. It can be intuitively monitored before and after the unit starts and after each rotor has been stopped. 4. Vibration protection at unit start-up 4.12 Strict operation procedures Operators should strictly observe Operational procedures should be followed immediately when the vibration exceeds the standard, especially when the vibration below the critical level exceeds the limit. Destroy the vacuum. It is strictly forbidden to speed up the warming up to page 35. Attention should be paid to determining the scope of the retrofit as soon as possible, which will directly affect the design and delivery of the hardware side and the final confirmation of the software side configuration. If changes are involved in the changes, This will eventually lead to postponement of the project duration. If the project is delayed, it will be large, and the daily workload will increase. This will cause the engineering staff to become extremely tired and prone to errors or fatalities. The line printed hidden dangers.

3.4 The signing of official documents Whether it is the preparation of business contracts or the preparation of technical agreements, or signing minutes. Pay attention to word accuracy. Avoid jealousy.

The ambiguity that occurred led to all parties wrangling the timing of the project schedule. All parties must confirm the progress of the project according to their own actual conditions and strictly enforce it.

3.5 Data Management Each project must have a dedicated person to manage all the engineering data. At the same time, a list of data must be categorized for inquiries. These materials include engineering contracts, additional contracts, technical agreements, various meeting minutes, and parties to and from the fax attachments. Project Implementation Progress Hardware Configuration Call 5 Soft 1 Design Specification System Test Outline System Test Report Operation Manual Each sub-system of each sub-project is debugged, the system is sub-item commissioned, and design changes are recorded. 1 Each system software directory and procedure Kinds of hardware manuals, training plans, various training materials, project acceptance reports, incomplete project memoranda, etc.

4 Conclusion Each 0, transformation project is a complex and rigorous system engineering that requires multiple cooperation. Only through active cooperation between all parties to improve management, can we successfully complete the specific implementation of our many transformation projects. There are short and long terms, and the units are large and small, and the scope of the transformation is also narrow and narrow. The above-mentioned project implementation process is summarized, and the old unit 005 transformation project in North China is basically satisfied. All the above-mentioned transformation projects completed have passed type 1681 operation on schedule or ahead of schedule. All the indicators are in line with the requirements of the bidding book of the power plant, except that individual systems have an impact on the automatic input due to the performance of the old equipment, and are well received by the power plant users. This shows that our reform design proposal is correct and management is scientific and feasible. The transformation of the old units has improved the stability of the unit operation, improved the degree of automation of the management and maintenance of the power plant, and reduced the cost of power generation. Improve the working conditions, but also brought huge economic benefits to the power plant. Received the date 2001 ye 919 quality is the guarantee for the survival of enterprises!