JPH04191610A - Method for detecting abrasion quantity of bush of pump shaft - Google Patents

Abstract

PURPOSE:To accurately detect abrasion quantity on the basis of proper measured data by storing only the max. displacement within a predetermined period among the detection values of the displacement in the radius direction of a rotary shaft in the vicinity of a bush. CONSTITUTION:The clearance C between a rotary shaft 13 and a bush 12 is detected by a non-contact type displacement sensor 14 and sent to an operational processor 15 to be subjected to the comparative operation with the displacement corresponding to the initial clearance or the displacement corresponding to a limit clearance. When the max. detection value is larger than the initial displacement, the abrasion of the bush 12 is judged to be generated to store the value of abrasion. Thereafter, the displacement of the next period is detected in the same way to be subjected to comparative operation and the stored value is rewritten if necessary and, when the value of abrasion exceeds the displacement corresponding to the limit clearance, an alarm is emitted. By this method, the abrasion quantity of the bush can be accurately detected and it can be also prevented that measured data becomes excessive.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the wear amount of a bushing on a pump shaft of a multi-stage centrifugal pump.

[Prior Art] In general, multi-stage centrifugal pumps installed in LNG plants, etc. have a bearing (radial bearing) that supports the rotating shaft (pump shaft), and a bearing that holds the rotating shaft with a predetermined clearance. A bush (slus I - bearing) is provided.

If this bushing wears out, there is a risk that the impeller or inducer that assists suction may come into contact with the gauging, leading to damage or a serious accident. For this reason, a limit clearance is set for the clearance between the rotating shaft and the bushing, and countermeasures such as replacing the bushing are taken before the wear progresses and the clearance does not exceed this value.

[Problems to be Solved by the Invention] However, since the bushing is located inside the gauging, this clearance cannot be measured visually or by other means, and it would be costly to disassemble and check. . Therefore, it is desirable to constantly monitor bushing wear directly or indirectly using sensors, but since pumps are in service for quite a long time, accumulating this data would exceed the capacity of a normal computer. , not realistic.

Further, as shown in FIG. 3, if the pump 1 has a horizontal axis, when the pump is stopped, the rotating shaft 2 moves down from the predetermined axial center position shown by the two-dot chain line in the figure, and surrounds the rotating shaft 2. You will be riding on top of Bush 3. Therefore, at this time, the non-contact sensor 5 provided between the inducer 4 and the bushing 3
If the displacement of the rotating shaft 2 is measured at , the bushing wear amount can be calculated from the difference between this displacement and the initial displacement (clearance). However, in the case of a vertical shaft pump, there is no time when the state is suitable for such measurement, and simply measuring the clearance one-off does not mean that the amount of wear has been detected.

For this reason, it is possible to reduce the amount of data by setting the continuous displacement measurement period at intervals and treating the maximum value within that period as the bush wear amount, but it is difficult to select this measurement period. .

This means that the displacement (runout) of the pump's rotating shaft causes the pump flow rate to
This is because it varies greatly depending on the type of fluid, operating conditions such as starting and stopping, and the individual mechanical characteristics of the pump, and this has already been confirmed by the inventors' actual measurement of the displacement of the pump rotation shaft. . Therefore, with intermittent measurement, there is a risk that proper detection may not be performed.

In view of the above circumstances, the present invention was devised to provide a method for detecting the wear amount of a bushing on a pump shaft, which can accurately detect the amount of wear on a bushing and which does not generate too much measurement data.

[Means and effects for solving the problem] When detecting the amount of wear on a bushing that holds the rotating shaft of a pump with a predetermined clearance, the present invention detects the radial displacement of the rotating shaft in the vicinity of the bushing in a non-contact manner. Continuously detects the displacement using the formula sensor, stores only the maximum displacement within a predetermined period of these detected values, compares this value with the detected values obtained from subsequent detections, and selects the larger one. A new value is stored, and the wear amount of the bushing is detected based on this stored displacement value.

This method makes it possible to accurately detect the amount of wear on the bushings.

[Example] Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, with reference to FIG. 2, an apparatus for carrying out the method for detecting the wear amount of a bushing on a pump shaft according to the present invention will be explained.

In this device, a displacement sensor 14, which is a non-contact sensor for detecting the radial displacement of the rotating shaft 13, is provided near the bush 12 of the vertical shaft pump 11, and a predetermined calculation is performed based on the information of this sensor 14. and an arithmetic processing unit that performs storage (
A computer) 15 is provided.

The bushing 12 is formed integrally with the casing 18 so as to surround the rotating shaft 13 between the impeller 16 and the inducer 17, and is spaced at a predetermined interval, for example, 0.211IIl.
The rotating shaft 13 is held with a clearance C of .

The displacement sensor 14 is provided between the bush 12 and the inducer 17, and is attached to the casing 18 so that its detection portion 19 faces the outer surface of the rotating shaft 13.

While the pump 11 is in operation, it always operates and continuously sends its detected value (displacement S) to the arithmetic processing unit 15.

The arithmetic processing unit 15 has predetermined data written in its storage unit 20 in advance, such as a displacement S0 corresponding to the initial clearance C0 and a displacement 88 corresponding to the limit clearance C1 (for example, 0.5 ni), and the data detected by the arithmetic unit 21. Comparison calculations between values and stored values are performed, and re-storage and memory deletion are performed depending on the results of the calculations. Further, the output section 22 allows stored values or detected values to be printed out or displayed on a display as necessary.

Next, with reference to FIG. 1, an embodiment of the method for detecting the wear amount of a bushing on a pump shaft according to the present invention will be described as the effect of the above configuration.

When detecting the amount of wear on the bushings of a multi-stage vertical shaft pump, etc., the displacement sensor 14 is activated at the same time as the pump 11 is in operation to detect the displacement S of the rotating shaft 13.ST1) The detected displacement value (S) is calculated. It is sent to the processing device 15.

The arithmetic processing unit 15 calculates, from the detected value S during the predetermined period of work,
The maximum value S(J)wax is extracted (ST2), and this value s(J)nax is compared with the displacement S0 corresponding to the initial clearance (ST3).

As a result of this calculation, if the maximum detected value S (i) Ilax is smaller than the initial displacement S0, it is determined that there is no wear on the bushing 12, and the next step is performed without storing the maximum detected value S (1) nax. Detection of the period (If) immediately continues. Then, when the maximum detected value S (Owax is larger than the initial displacement S0, it is determined that wear of the bushing 12 has occurred, and the value S (1) iax is stored as the bush wear displacement S (ST4) .

After that, displacement detection for the next period (n) is performed in the same way (
ST 5) Extract the maximum value S (1) wax ST 6) Compare this maximum value S (1) ax with the stored bushing wear displacement S8 (ST 7)
.

As a result of this calculation, the maximum value S (1) IIax is the stored value (
Ss ), this maximum value S (1)
Displacement detection for the next period is directly performed without storing IIax.

If the detected maximum value S (summer) raax is larger than the bushing wear displacement S8, this maximum value S (
1) Rewrite the memory by setting Ilax as a new bush wear displacement Ss. That is, the maximum value S m wa stored last time
Delete x (ST 8).

Also, when this bushing wear displacement S- exceeds the displacement Sa corresponding to the limit clearance (ST9), the bushing 1
It is assumed that it is time for inspection or replacement in step 2, and an alarm is issued to alert the administrator. If the limit displacement S has not been reached, detection for the next period is continued, and thereafter, which detection and storage are repeated until the service period of the pump 11 ends (STlG).

Therefore, when the pump 11 is operated for a long time and the bushing 12 gradually wears out and the clearance C increases, this condition is detected as an increase in the maximum displacement SlaX, and when a dangerous wear limit is reached. The situation can be grasped immediately.

In this way, the displacement sensor 12 and the arithmetic processing unit 15 are provided to continuously detect the displacement S in the radial direction of the rotating shaft 13,
Only the maximum displacement sl1ax is stored, and this value sl1ax is compared with the detected value S obtained by subsequent detections, and the larger value is newly stored, so the calculation process The device 15 only performs calculations on data within each predetermined period (I, I, . . .), so there is no need for the storage capacity to be huge enough to correspond to the period in which the pump is in use, and moreover, it can be used continuously. Since the detection is carried out using the same method, the amount of wear on the bushings can be detected accurately and is extremely practical.

Since the displacement sensor 14 is a non-contact type, the pump 1
1 has fewer restrictions on the position, and the effect on pump function can be minimized.

Furthermore, since it is possible to collect data on the runout of the rotating shaft 13 as appropriate in relation to the maximum displacement s nax, it can also be used as background data to investigate the cause of wear, such as when wear progresses abnormally quickly. It is possible.

Note that in this embodiment, the detection period (1, If,...)
is set as appropriate, and the maximum value sl1ax is compared with the stored maximum value (Ss).
If (I) llax is taken, the detected value S is always stored without extracting the maximum value in the next period.
) nax may be replaced or deleted one after another.

Further, in the above embodiment, the present invention is applied to a vertical shaft pump having a multi-stage impeller, but the present invention is not limited to this, and can be applied to various pumps equipped with a rotating shaft and a bush. .

[Effects of the Invention] In summary, according to the present invention, the following excellent effects are achieved.

The displacement of the rotating shaft near the bushing is continuously detected using a non-contact % type % sensor. Of these detected values, only the maximum displacement is memorized, and this value is compared with subsequent detected values. Since the amount of wear on the bushings is detected by newly storing the larger value based on the axis, the amount of wear on the bushings can be detected accurately, and the storage capacity can be used for pump use by preventing too much measurement data. It is extremely practical as it does not need to correspond to a period of time.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an embodiment of the method for detecting the amount of wear on a bushing of a pump shaft according to the present invention, FIG. 2 is a side sectional view showing an apparatus for carrying out the method, and FIG. FIG. 3 is a side sectional view for explaining a bush wear amount detection method. In the figure, S is a detected value (displacement), 5Ilax is the maximum value of the detected values that is the maximum displacement, S@ is the bushing wear displacement that is the stored displacement value, 12 is the bushing, 13 is the rotation axis, and C is the clearance. = 11 −

Claims (1)

[Claims] 1. When detecting the wear amount of the bushing that holds the rotating shaft of the pump with a predetermined clearance, the radial displacement of the rotating shaft in the vicinity of the bushing is continuously detected using a non-contact sensor, and these detected values are Of these, only the maximum displacement within a predetermined period is memorized, this value is compared with the detected value obtained by subsequent detection, the larger value is newly memorized, and this memorized displacement value is used. A method for detecting the wear amount of a bush on a pump shaft, characterized by detecting the amount of wear on the bush.