CN110608887A - Method for judging turbine oil film whirl vibration fault - Google Patents

Abstract

The invention relates to a method for judging a turbine oil film whirl vibration fault, which comprises the following steps of: the method includes the steps of performing vibration data acquisition; carrying out spectrum analysis; performing a speed-up and speed-down vibration test; fourthly, analyzing acceleration and deceleration vibration data; fifthly, carrying out a temperature change test; sixthly, analyzing oil temperature test data. The invention designs the lifting rotating speed test and the oil temperature changing test to judge the oil film whirl vibration fault, greatly improves the judgment accuracy, has simple, convenient, quick and effective judgment process, does not depend on experience, can be judged by any worker according to the method, and can well guide production application.

Description

Method for judging turbine oil film whirl vibration fault

Technical Field

The invention belongs to the technical field of steam turbine detection, and particularly relates to a method for judging a turbine oil film whirl vibration fault.

Background

The problem of overlarge vibration of a steam turbine can occur in the operation process, and the vibration of a steam turbine generator unit bearing with the capacity of 300MW and above needs to be processed if the vibration exceeds 120 mu m according to the standard regulation. Similarly, the reason for the excessive vibration may be various, and if the reason for the excessive vibration needs to be analyzed and judged first for effective treatment, the targeted treatment can be performed only after the reason is determined.

Among the various causes that cause excessive vibration in the turbine, oil whirl is a relatively difficult type of failure to determine. The fault characteristics of the device are close to those of steam flow excitation and collision and abrasion, so that the device is easy to confuse and not easy to distinguish, but the treatment method of the device is greatly different from those of the steam flow excitation and collision and abrasion, so that the device is important to judge whether the device can accurately judge. And oil film whirl will develop into oil film vibration if it can not be timely controlled, the destructive power of oil film vibration is very large, the amplitude is increased and becomes a divergent trend, and the damage and even disintegration of equipment can be caused, thus causing a malignant accident. However, at present, the oil film whirl vibration fault can be judged only by depending on rich experience of experts, and a simple, effective and reliable judgment method is not provided. This causes great inconvenience to the safe operation and maintenance of the power plant. Therefore, it is necessary to provide an effective and highly operable method for determining oil film whirl vibration failure.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for judging the oil film whirl vibration fault of the steam turbine, which converts the previous work of analysis depending on the experience of a vibration diagnostician into simple, convenient, quick, reliable and stable method steps and can finish the judgment of the fault type by any power plant worker according to the operation steps.

The invention adopts the following specific technical scheme:

a method for judging the turbine oil film whirl vibration fault is characterized in that: the method comprises the following steps:

the method comprises the steps of performing vibration data acquisition, and acquiring X, Y-direction vibration data of a bearing with overlarge vibration by using a professional vibration data acquisition and analysis instrument in a unit working state;

checking a vibration spectrogram;

if a single-peak low-frequency vibration component exists in the spectrogram and the component amplitude reaches more than 20% of the pass frequency amplitude, judging that the unit possibly has the problem of oil film whirl, and switching to the next step of judgment;

the absence of components within this frequency range can determine that there is no oil whirl;

keeping parameters such as vacuum and lubricating oil temperature of the unit unchanged, gradually reducing the rotating speed of the unit to 50% of the working rotating speed, then increasing the rotating speed to the working rotating speed, and recording vibration data in the whole process;

fourthly, whether the frequency of the low-frequency vibration component in the vibration frequency spectrogram at each rotating speed changes along with the change of the rotating speed is checked;

if the oil film vortex motion is changed, judging that the oil film vortex motion possibly exists, and switching to the next step of judgment;

if the frequency does not change but remains consistent throughout, it can be determined that there is no oil whirl;

fifthly, gradually raising the temperature of the bearing lubricating oil from a normal value by 5 ℃ while keeping other operation parameters such as the rotating speed of the unit unchanged, and staying for 5 minutes every time when the temperature is raised by 1 ℃ and recording vibration data; then reducing the temperature of the lubricating oil to 5 ℃ lower than the normal temperature, staying for 5 minutes at 1 ℃ during the same period, and recording vibration data;

sixthly, checking the low-frequency vibration component amplitude of the bearing at each temperature;

if the component amplitude shows the trend of decreasing along with the temperature increase and increasing along with the temperature decrease, the problem that the unit vibrates too much can be finally judged to be oil film whirl;

if the trend does not exist, the problem that the unit vibration is too large can be finally judged not to be caused by oil film vortex.

Furthermore, the single-peak low-frequency vibration component of the second step is a single-peak low-frequency vibration component with frequency multiplication of 0.3-0.5.

The invention has the advantages and beneficial effects that:

the invention designs the lifting rotating speed test and the oil temperature changing test to judge the oil film whirl vibration fault, greatly improves the judgment accuracy, has simple, convenient, quick and effective judgment process, does not depend on experience, can be judged by any worker according to the method, and can well guide production application.

Drawings

Fig. 1 is a schematic diagram of the present invention.

Detailed Description

The present invention is further described in the following examples, but the technical content described in the examples is illustrative and not restrictive, and the scope of the present invention should not be limited thereby.

The invention discloses a method for judging a turbine oil film whirl vibration fault, which is characterized in that as shown in figure 1: the method comprises the following steps:

the method comprises the steps of performing vibration data acquisition, and acquiring X, Y-direction vibration data of a bearing with overlarge vibration by using a professional vibration data acquisition and analysis instrument in a unit working state;

checking a vibration spectrogram;

if the frequency spectrogram has a single-peak low-frequency vibration component with frequency multiplication of 0.3-0.5 and the component amplitude reaches more than 20% of the pass frequency amplitude, judging that the unit possibly has the problem of oil film whirl, and switching to the next step of judgment;

the absence of components within this frequency range can determine that there is no oil whirl;

keeping parameters such as vacuum and lubricating oil temperature of the unit unchanged, gradually reducing the rotating speed of the unit to 50% of the working rotating speed, then increasing the rotating speed to the working rotating speed, and recording vibration data in the whole process;

fourthly, whether the frequency of the low-frequency vibration component in the vibration frequency spectrogram at each rotating speed changes along with the change of the rotating speed is checked;

if the oil film vortex motion is changed, judging that the oil film vortex motion possibly exists, and switching to the next step of judgment;

if the frequency does not change but remains consistent throughout, it can be determined that there is no oil whirl;

fifthly, gradually raising the temperature of the bearing lubricating oil from a normal value by 5 ℃ while keeping other operation parameters such as the rotating speed of the unit unchanged, and staying for 5 minutes every time when the temperature is raised by 1 ℃ and recording vibration data; then reducing the temperature of the lubricating oil to 5 ℃ lower than the normal temperature, staying for 5 minutes at 1 ℃ during the same period, and recording vibration data;

sixthly, checking the low-frequency vibration component amplitude of the bearing at each temperature;

if the component amplitude shows the trend of decreasing along with the temperature increase and increasing along with the temperature decrease, the problem that the unit vibrates too much can be finally judged to be oil film whirl;

if the trend does not exist, the problem that the unit vibration is too large can be finally judged not to be caused by oil film vortex.

Examples

Taking the vibration fault treatment of the bearing No. 1 of the unit No. 4 of a certain power plant as an example, the bearing has the problem of vibration increase in the operation process.

In the first step, a professional instrument is used for testing X, Y vibration data of the unit in two directions under the working state, a spectrogram is generated, and the process is completed by professional software.

And secondly, performing spectrum analysis according to the spectrogram. It was found that X, Y vibration in both directions has a large vibration component at a frequency of 25Hz, where the X-direction vibration component is 56 μm and the pass frequency amplitude is 83 μm; the vibration component in Y direction is 45 μm, the pass frequency amplitude is 78 μm, the ratio is 67% and 58%, respectively, and both exceed 20%. The working frequency of the unit is 50Hz, and 25Hz is just 0.5 frequency multiplication. And (4) judging that the unit possibly has the problem of oil film whirling by combining the two points, and switching to the next judgment.

And thirdly, carrying out a lifting rotating speed test. Keeping parameters such as vacuum and lubricating oil temperature of the unit unchanged, gradually reducing the rotating speed of the unit to 50% of the working rotating speed, namely 1500rpm, then increasing the rotating speed to the working rotating speed, and recording vibration data in the whole process.

And fourthly, analyzing the acceleration and deceleration vibration data. The frequency of the low-frequency component of the unit is always kept 50% of the power frequency in the whole speed increasing and reducing process, namely 0.5 frequency doubling. While the non-fixed frequency remains unchanged. Therefore, the unit vibration fault is still judged to be oil film whirl, and the next judgment is needed.

And fifthly, carrying out a variable oil temperature test. Keeping other operation parameters such as the rotating speed of the unit and the like unchanged, gradually increasing the temperature of the bearing lubricating oil from a normal value by 5 ℃, staying for 5 minutes every time when the temperature is increased by 1 ℃, and recording vibration data; the temperature of the lubricating oil was then lowered to 5 ℃ below the normal temperature, during which time again 5 minutes remained at 1 ℃ change and vibration data were recorded.

And sixthly, analyzing the test data of the variable oil temperature. The 0.5 frequency multiplication vibration component of the unit shows a trend that the vibration component is reduced along with the temperature increase and is increased along with the temperature decrease in the variable oil temperature test.

The invention designs the lifting rotating speed test and the oil temperature changing test to judge the oil film whirl vibration fault, greatly improves the judgment accuracy, has simple, convenient, quick and effective judgment process, does not depend on experience, can be judged by any worker according to the method, and can well guide production application.

Claims (2)

1. A method for judging the turbine oil film whirl vibration fault is characterized in that: the method comprises the following steps:

the method comprises the steps of performing vibration data acquisition, and acquiring X, Y-direction vibration data of a bearing with overlarge vibration by using a professional vibration data acquisition and analysis instrument in a unit working state;

checking a vibration spectrogram;

if a single-peak low-frequency vibration component exists in the spectrogram and the component amplitude reaches more than 20% of the pass frequency amplitude, judging that the unit possibly has the problem of oil film whirl, and switching to the next step of judgment;

the absence of components within this frequency range can determine that there is no oil whirl;

keeping parameters such as vacuum and lubricating oil temperature of the unit unchanged, gradually reducing the rotating speed of the unit to 50% of the working rotating speed, then increasing the rotating speed to the working rotating speed, and recording vibration data in the whole process;

fourthly, whether the frequency of the low-frequency vibration component in the vibration frequency spectrogram at each rotating speed changes along with the change of the rotating speed is checked;

if the oil film vortex motion is changed, judging that the oil film vortex motion possibly exists, and switching to the next step of judgment;

if the frequency does not change but remains consistent throughout, it can be determined that there is no oil whirl;

fifthly, gradually raising the temperature of the bearing lubricating oil from a normal value by 5 ℃ while keeping other operation parameters such as the rotating speed of the unit unchanged, and staying for 5 minutes every time when the temperature is raised by 1 ℃ and recording vibration data; then reducing the temperature of the lubricating oil to 5 ℃ lower than the normal temperature, staying for 5 minutes at 1 ℃ during the same period, and recording vibration data;

sixthly, checking the low-frequency vibration component amplitude of the bearing at each temperature;

if the component amplitude shows the trend of decreasing along with the temperature increase and increasing along with the temperature decrease, the problem that the unit vibrates too much can be finally judged to be oil film whirl;

if the trend does not exist, the problem that the unit vibration is too large can be finally judged not to be caused by oil film vortex.

2. The method for determining the oil film whirl vibration fault of the steam turbine according to claim 1, wherein: and secondly, the unimodal low-frequency vibration component is a 0.3-0.5 frequency-doubled unimodal low-frequency vibration component.