JPH029969A - Deterioration diagnosis for lng pump - Google Patents

Abstract

PURPOSE:To correctly detect the vibration at various sections of an LNG pump by arranging vibration sensors used to diagnose the deterioration of the LNG pump at multiple bearing sections supporting the rotary shaft of the LNG pump. CONSTITUTION:The major portion of an LNG pump 31 is constituted of a rotary shaft 36 supported by bearings 34 and 35 coupled with multiple casings 32 and 33, a motor 37 rotating the rotary shaft 36, and an impeller 38 sucking LNG as the rotary shaft 36 is rotated. The deterioration of the LNG pump 31 is diagnosed by using vibration sensors. In this case, vibration sensors 1 and 2 are arranged on the casings 32 and 33. Signal lines 3 and 4 are guided to a signal processing unit from the vibration sensors 1 and 2. The vibration at various sections of the LNG pump 31 transmitted to the bearings 34 and 35 is correctly detected without detecting the external vibration not related to the LNG pump 31.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of diagnosing deterioration of an LNG pump using a vibration sensor.

[Prior Art] Since an LNG pump is operated while immersed in LNG, its overhaul, including safety measures, is extremely expensive. Therefore, it is necessary to reduce the cost of overballing by increasing the operation time of the LNG pump until it overballs as much as possible.As a specific method, there is a need to reduce the deterioration of the LNG pump. The current method is to use a vibration sensor to diagnose the degree of damage and make a decision as to whether to perform an immediate overhaul or continue operation.

The LNG pump 31 has a bearing link 34.35 fitted in a hair casing 32.33 as shown in FIG.
The main components are a rotating shaft 36 supported by a rotating shaft 36, an electric motor 37 that rotates this rotating shaft 36, and an impeller 38 that pumps up t-NG as the rotating shaft 30 rotates. When diagnosing the degree of failure of the 6fun-NG pump 3 which is housed in three pump casings using a vibration sensor, the vibration sensor 40 is 〉・It is attached to the outer periphery of the pump casing 39σ) of the pump 31, and the signal A1 which is generated by this vibration sensor 4° is connected to the signal line 41 (
The language was directed to an embedded device (not shown).

[Problems to be Solved by the Invention] The above-mentioned conventional technology has the following problems. In other words, in the method of measuring the degree of deterioration of the LNG pump since b'C using a vibration sensor, the vibration sensor is
The method was to attach it to the pump casing of an NG pump and measure the vibration of the entire pump, which eliminates vibration signals related to pump deterioration, and also captures external noise unrelated to the pump. The signal could not be accurately grasped, and the original purpose could not be fully achieved.

In this example, the vibration sensor obtains two types of signals: vibration displacement and vibration acceleration. Figure 5(a)-(d)
The vibration sensor is housed in the body of a conventional pump.
It shows changes in the vibration signal before and after the power supply to the pump drive motor is stopped. The graph in (a) is y
The axis is time, the y-axis is vibration displacement and vibration acceleration, and the composite vibration is recorded without frequency discrimination, etc. (b
) The graph in (c) shows the relationship between vibration displacement, vibration acceleration, and frequency, with the y-axis representing frequency and the y-axis representing vibration displacement and vibration acceleration.In the graph (c), the y-axis represents frequency and the y-axis represents vibration displacement and vibration acceleration. Vibration displacement, the y-axis is time, and the relationship between them is expressed in three dimensions. Note that the graph in (d) has the same specifications as the graph in (c), but in order to verify the vibration frequency fluctuation before and after the power supply to the pump drive motor is stopped, the vibration displacement and time Both are taken on the same y-axis.

As seen in the figures (a) and (b), there is a large signal in the vicinity of 251-(z for one displacement and a low frequency part around 0.15Hz for vibration acceleration. The signal was assumed to be a vibration signal caused by the rotation and deterioration of the LNG pump, but as a result of conducting a so-called three-dimensional analysis in which the power to the pump drive motor was cut off and the vibration signals before and after that were frequency analyzed, it was determined that the It was found that the vibration signal was not caused by the rotation and deterioration of the NG pump.In other words, if the signal of this frequency component was caused by the rotation and deterioration of the pump, it would be due to a decrease in the rotation speed of the pump. As the frequency increases, the intensity should gradually decrease to zero, and the intensity peak should also move to a lower frequency.By turning off the motor, the intensity of the frequency component of, for example, 25 Hz will decrease, but as shown in Fig. 5. As seen in (c) and (d), the intensity does not reach zero even after the pump stops rotating.The intensity peak also gradually moves to lower frequencies from 251-1 z. However, such a phenomenon has not appeared.In this way, in the conventional mounting position of the vibration sensor, signals unrelated to pump rotation and deterioration are contained, so this signal and pump It has been extremely difficult to distinguish and understand signals related to deterioration.

It is an object of the present invention to solve the above-mentioned problems of conventional UC technology and to provide a method for diagnosing deterioration of an LNG pump that can accurately grasp vibration signals related to deterioration of the LNG pump.

1. Means for Solving the Problems] A method for diagnosing deterioration of an LNG pump according to the present invention
In the method of diagnosing the deterioration of the G pump using a vibration sensor, this is the Jf method for diagnosing the deterioration of the LNG pump, in which the vibration sensor is installed at two bearing parts.

[Function] In the method for diagnosing deterioration of an LNG pump according to the present invention, a vibration sensor is used in 1. , is attached to two bearings that support the shaft of the NG pump, and vibration signals are obtained from each vibration sensor. Therefore, it is possible to understand not only the vibration signal of the heavily deteriorated bear link part, but also the vibration signal of other parts of the LNG pump, as the vibration is transmitted to the outside through the bearing part. . In addition, since the vibration sensor is placed close to the vibration source, external vibration signals unrelated to the L and N G pumps are not detected.
Is it possible to accurately grasp the degree of inferiority of the LNG pump?

Furthermore, the position of the vibration source can be estimated by comparing and investigating the timing at which vibration signals from two or more vibration sensors are generated.

[Example] An example of the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. 1 is an explanatory diagram showing the installation positions of vibration sensors when carrying out a deterioration diagnosis method for an LNG pump according to an embodiment of the present invention. 31 rotation axis 3
The bearing 6 is attached to the casing 32 of the bearing 34 and the gauging 33 of the bearing 35. Signal lines 3 and 4 are led from the vibration sensor 1 and the vibration sensor 2 to a signal processing device, respectively. The vibration signals of the bearings 34 and 35 guided to the signal processing device by the signal lines 3 and 4 are amplified and processed by the circuit shown in the vibration amplifier block diagram of FIG.

To explain this block diagram in detail, the charge corresponding to the acceleration of vibration generated by the sensor 11 is converted into a voltage by the charge-voltage converter 12, and amplified by the preamplifier 13. Thereafter, it is divided into a block that extracts the vibration acceleration signal and a block that integrates the vibration acceleration signal once to extract the vibration velocity signal. In the block that extracts the vibration acceleration signal, the vibration acceleration signal is passed through the bypass filter 1.
4 and a low-pass filter] 5 to extract only signals with necessary frequency components. After being further amplified by the amplifier 16, it is output from the vibration acceleration output terminal 17. - In the block that takes the vibrational velocity signal and extracts the mountain number, the vibrational acceleration signal is integrated once by the acceleration-velocity converter 18 and converted into a vibrational 0) velocity signal. Then, the signal is passed through a bypass filter] 8 and a low-pass filter, and only signals with necessary frequency components are output. After being further amplified by the amplifier 2o, it is output as a vibration velocity signal from the vibration velocity output terminal 21. Although the above explanation of the block diagram was made for one sensor and is omitted in FIG. 2, there are actually two series of such blocks corresponding to each vibration sensor.

The third LA is a system diagram showing the hardware configuration when implementing the I-NG pump deterioration diagnosis method according to an embodiment of the present invention. In this figure, the part A surrounded by the dashed line is
Parts B and C, which are located in the central station and are also surrounded by dashed lines, are located in the operation room. The vibration velocity and vibration acceleration signals explained in FIG. 2 are transmitted in time series to the computer 22 of the central station 1 via the transmission device 221, and are further selected and stored in the transmission unit 223.

These signals are then transmitted to the CRT in the operation room.
In addition to being able to output to 23k, the recording section 26
It is now possible to do ara 1 ~ putu l ~, and L N
Simple diagnosis of the degree of deterioration of the G pump and Jt life analysis 7.1
(Yes, it is possible. Also, thresholds for vibration speed and vibration acceleration are input to the electric 3IP! 22, and when each signal exceeds this threshold, the microcontroller 22
Judging from step 4, the operation room's fuzer 24 will issue an alarm. Furthermore, the vibration is LNG
Precise diagnosis to understand which part of the pump is causing the problem and what is causing the problem can also be carried out by collecting signals with the analog measurement type 222 and analyzing them with the signal processing device 251 in the operation room. The data can be outputted to the Cf1T 252 and outputted to the recording section 253, and created on the Rev-1 using the XY plotter 254.

j) In addition to the vibration signal of the bearing part, which is severely deteriorated, it is also necessary to clearly understand the vibration signal of the L N (embopu) pond part. Since the vibration sensor is installed in a nearby location, l = N G
It is possible to accurately determine the degree of failure of the I=NG pump without receiving external vibration signals unrelated to the pump.
In addition, compare the timing at which the vibration signal a from the second vibration sensor ([^1 onwards]) is generated.
, "The position of the vibration source can be deduced by inspecting the vibration source.

Based on these findings, we have created an LNG pump deterioration diagnosis method, q, and an abnormality cause analysis report. Among these, the diagnosis report records the vibration velocity and acceleration (units are mm/sec and gravitational acceleration G) at a certain point and their changes over time. Also, the abnormality cause analysis report records the following: The estimated cause of vibration, such as a scratch on the outer ring of a bearing, and the probability that the estimate is correct are entered.

In addition, in this example, two sensors are N (# digit example?
If necessary, three or more sensors may be used, and the same effects as in this example can be obtained.

[Effects of the Invention] According to the present invention, it is possible to accurately grasp the degree of deterioration of the LNG pump, so the time from overhaul to overhaul can be extended compared to before, and the overhaul of the LNG pump can be completed. The industrial effect is great because it can reduce the cost of 2).

[Brief explanation of the drawing]

FIG. 1 does not show the mounting position of a vibration sensor according to an embodiment of the present invention.1. , Fig. 2 is a vibration amplifier block diagram of an embodiment of the invention, Fig. 3 is a system diagram showing the hardware configuration of an embodiment of the invention, and Fig. 4 is a system diagram showing the hardware configuration of an embodiment of the invention. f+' is L indicating the position where the next vibration sensor is housed.
Cross-sectional view of the N G pump, Figures 5 (εL) to ((i) are graphs showing the vibration signal data of the mounting position of the vibration sensor f & 9 ■, 2... Vibration sensor, 3 .4... Signal line, 11 ・
Vibration sensor, 12...Charge-voltage converter, 13...1]
? f position amplifier, 14・Bypass filter, 15・Low pass filter, I GtX'l detector, 17・・Vibration acceleration output terminal, 18・Acceleration-velocity converter, 1・・Low pass filter, 20・Amplifier, 2 ]・1
1J・i dynamic speed output terminal, 22・Computer, 23・Cr
T, 24 ・Huser, 15・Computer, 26...Recording section (external output), 31...L N ('r pump, 32.
33...Bear link casing, 34.35...Bear link, 36.Rotating shaft, 37.Electric motor, 38.3 impellers...Bonpukenken, 40.Vibration sensor, -1]
・Line 13, 221 Transmission equipment, 222... Analog measurement board, 223... Transmission unit I~, 224... Microphone 177 Near controller, 225 = -CRT22
6... Recording unit (external output), 251... Signal processing device, 252... CRT253...
・3rd Sk club, 251I XY Firo Vri.

Claims (1)

[Claims] A method for diagnosing deterioration of an LNG pump using a vibration sensor, characterized in that the vibration sensors are installed at two bearing parts.