JPH10205478A - Pump device for liquefied gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of measurement of shaft vibration by composing an under-liquid contactless shaft vibromember for sensing vibration of a rotary shaft and arranged near hydrostatic bearings, of a sensor and a head amplifier for amplifying output voltage of the sensor, both being housed in the vibrometer, and thereby equalizing temperature environments of the sensor and the head amplifier. SOLUTION: In a submerged pump body 5 for liquefied gas, an inducer 5B, a plurality of impellers 5C and a submerged motor rotor 5D are fixed to a pump rotary shaft 5A. They are supported on hydrostatic bearings 5E to 5G. In such a case, an amplifier built-in type under-liquid contactless shaft vibrometer 15 is prepared by housing a sensor and a head amplifier integrated with each other inside a metal case. A sensor cable is connected thereto through a connector 16. Temperature environments of the sensor and the head amplifier are equalized to each other, for eliminating a problem of easy fluctuation of output voltage characteristics. The under-liquid contactless shaft vibrometer is arranged near the upper hydrostatic bearing 5E alone, so that a manufacturing cost is reduced including accessory parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquefied gas pump device using a hydrostatic bearing.

[0002]

2. Description of the Related Art As a liquefied gas pump device for transporting a liquefied gas such as liquefied natural gas, there is, for example, a submerged pump device for a liquefied gas tank with a built-in tank used in a liquefied gas tank. In the gas pump device,
Conventionally, a hydrostatic bearing has been employed in order to prolong the life of the bearing.

An example of a liquefied gas pump device will be described with reference to FIG. 5 by using a submerged pump device for a liquefied gas tank.

[0004] 1 is a liquefied gas tank, 1 a is a ceiling plate of the gas tank 1, and 2 is a liquid pumping pipe suspended in the liquefied gas tank 1. A suction valve 3 is attached to a lower end of a liquid pumping pipe 2 suspended in the liquefied gas tank 1, and a submerged pump main body 5 for the liquefied gas tank is mounted on a seat surface 4 of the liquid pumping pipe 2.
Is installed. Reference numeral 6 denotes a plurality of discharge ports provided on the outer periphery of the submerged pump main body 5. A head plate 7 having a pump lifting mechanism is provided at the top of the liquid pumping tube 2. 8 is a lifting wire, 9 is a power supply cable,
Reference numeral 10 denotes a hoist.

The submerged pump main body 5 for a liquefied gas tank has, for example, a depth of about 50 m inside a pumping pipe 2 vertically suspended from a ceiling plate 1a of the liquefied gas tank 1 by a lifting wire 8 from a head plate 7. And is seated on the lower seating surface 4 of the pumping pipe 2 and installed.

The submerged pump main body 5 for the liquefied gas tank includes:
When power is supplied by the power supply cable 9 and the operation of the pump is started, the liquefied gas is sucked from the suction valve 3, is pressurized, is discharged from the discharge port 6, and rises as shown by an arrow in the figure. The liquid rises in the liquid pipe 2 and is sent out to the discharge pipe 11.

In such a liquefied gas pump device, for example, as described in JP-A-8-296586, a motor is accommodated in a casing of a vertical shaft pump, and the shaft and impeller of the pump are rotated. A rotating shaft with an axial thrust balance device fixed to the upper part of the impeller and a hydrostatic bearing with a long bearing life and excellent vibration damping performance in the upper, middle and lower bearings. An auxiliary ball bearing is further attached to the bearing.

In the static pressure bearing of the liquefied gas pump device, high pressure liquefied gas discharged from the pump is guided to the static pressure bearing for lubrication. When the pump is started and stopped, the supply pressure to the static pressure bearing decreases. Therefore, the shaft oscillates to fill the gap of the hydrostatic bearing, and the wear of the hydrostatic bearing gradually progresses. For this reason, as technologies for monitoring the progress of wear of the hydrostatic bearing by monitoring the amount of whirling of the shaft, and detecting sudden failure of the hydrostatic bearing during operation due to abnormal wear, etc. ,
There is one disclosed in JP-A-5-118298.
According to this technique, a non-contact non-contact shaft vibrometer is provided near a middle hydrostatic bearing as an apparatus for detecting vibration of a rotary shaft, thereby monitoring shaft vibration during pump operation.

FIG. 6 shows a specific example of a submersible pump for a liquefied gas tank having a non-contact non-contact shaft vibrometer.

In the liquefied gas tank submerged pump main body 5, an inducer 5B, a plurality of impellers 5C, and a submerged motor rotor 5D attached for improving suction performance are fixed to a pump rotating shaft 5A. Structure and rotate together. The pump rotating shaft 5A, the inducer 5B, the plurality of impellers 5C, and the submerged motor rotor 5D are self-liquid lubricated hydrostatic bearings 5E, 5F,
It is supported in the radial direction by 5G. On the other hand, in the axial direction, the axial thrust is self-balanced by a thrust balance device including a balance disk 5J fixed to the pump rotating shaft 5A, floats in the liquid of the pump rotating body, and the auxiliary ball bearings 5H, 5I The thrust force does not act at all.

The non-contact non-contact shaft vibrometer has sensors 12A and 12B for detecting shaft vibration and the sensors 12A and 12B.
The head amplifier 13 for amplifying the output voltage of the sensor is provided separately, and the positions of the sensors 12A and 12B are
Of E, 5F and 5G, it is installed near two places of the upper hydrostatic bearing 5E and the intermediate hydrostatic bearing 5F. Further, the head amplifier 13 cannot be installed near the sensors 12A and 12B because the head amplifier box 14 in which the head amplifier 13 is stored requires a little space. For this reason, it has to be installed above the pump cover 5K or the like, and the sensor cables are connected between the sensors 12A and 12B and the head amplifier 13.

[0012]

In a submerged non-contact shaft vibrometer of a liquefied gas pump device using a static pressure bearing, a sensor and a head amplifier are separately provided, and the positions of the sensor and the head amplifier are respectively: Due to the structure of the liquefied gas pump device, the temperature environment conditions are different. For example, in the case of the submerged pump device for a liquefied gas tank shown in FIG.
Since the place where 2B is attached is inside the motor room, the temperature becomes higher by several degrees than the position of the head amplifier 13 due to the influence of heat generated by the motor.

[0013] The liquid temperature during operation of the liquefied gas pump device is:
Although the temperature is in the range of -162 ° C to -145 ° C, the output voltage characteristic of the conventional non-contact submerged shaft vibrometer changes as shown in FIG. 7 when the temperature condition is different. When such a change occurs, the apparent vibration becomes larger or smaller than the actual vibration of the shaft due to the shaft whirling, and the reliability of the vibrometer is impaired.

The non-contact non-contact shaft vibrometers are installed at two locations near the upper hydrostatic bearing 5E and the intermediate hydrostatic bearing 5F. If these can be provided at one location, cost reduction can be achieved. Can be.

An object of the present invention is to provide a liquefied gas pump device which can improve the reliability by a highly reliable non-contact submerged shaft vibrometer and can reduce the cost.

[0016]

SUMMARY OF THE INVENTION The object of the present invention is to provide a liquefied gas pump device comprising a hydrostatic bearing and a submerged non-contact shaft vibrometer arranged near the hydrostatic bearing for detecting vibration of a rotating shaft. The non-contact non-contact shaft vibrometer is achieved by incorporating a sensor and a head amplifier for amplifying an output voltage of the sensor.

Preferably, the non-contact shaft vibration meter with built-in amplifier is disposed on the uppermost hydrostatic bearing.

According to the above configuration, since the sensor and the head amplifier are integrated, the temperature environment of the sensor and the head amplifier become the same, and the output voltage characteristic does not change. Therefore, the reliability of the measurement of the shaft vibration is greatly improved. The reliability of the liquefied gas pump device can be improved.

Further, since there is no connecting portion of the sensor cable between the sensor and the head amplifier, and instrumentation is simplified, the cost can be reduced.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is a whirling mode diagram of a rotary shaft of a liquefied gas pump device, and FIG.
FIG. 3 is an enlarged view of the vicinity of a non-contact shaft vibration meter with built-in amplifier.

In the whirling mode of the pump rotating shaft, since the bearing effect of the balance disk 5J is large, as shown in the drawing, the whirling mode rotates around the intermediate hydrostatic bearing 5F. The bearing 5E is larger than the intermediate hydrostatic bearing 5F. In this embodiment, attention is paid to this fact, and the lower hydrostatic bearing 5G and the intermediate hydrostatic bearing 5 are mounted on the non-contact submerged shaft vibration meter 15 with built-in amplifier at the position of the upper hydrostatic bearing 5E.
F, abnormalities of the upper auxiliary ball bearing 5H and the middle auxiliary ball bearing 5I are detected.

Reference numeral 15 denotes a non-contact shaft vibration meter with built-in amplifier, in which a sensor and a head amplifier are housed in a metal case 15A. Reference numeral 16 denotes a connector for connecting a sensor cable.

Next, the detection of an abnormality by the non-contact non-contact shaft vibrometer 15 at the position of the upper hydrostatic bearing 5E will be described.

When the wear of the upper hydrostatic bearing 5E and the lower hydrostatic bearing 5G progresses, the pump starts and stops (large whirling).
And during operation (the hydrostatic bearings function to reduce whirling)
It can be seen from the gradual increase in vibration. Intermediate hydrostatic bearing 5
As the wear of F progresses, the rotating shaft is supported by the middle auxiliary ball bearing 5I during the start and stop of the pump.
Although no vibration caused by F occurs, the whirling of the shaft during operation increases, which indicates that the whirling of the upper hydrostatic bearing 5E also increases. When the upper auxiliary ball bearing 5H and the middle auxiliary ball bearing 5I are broken, it can be detected because vibration increases due to unbalance or rattling of the ball bearing.

According to this embodiment, the non-contact non-contact shaft vibrometer has a sensor and a head amplifier integrated with each other.
The temperature environment of the sensor and the head amplifier becomes the same. This solves the conventional problem that the output voltage characteristics are likely to change because the sensor and the head amplifier are separate and the temperature environment is different. Further, as shown in FIG. 4, the output voltage characteristic of the submerged non-contact shaft vibrometer 15 hardly changes because of the same temperature environment. The reliability of the vibration measurement is greatly improved, and thereby the reliability of the liquefied gas pump device can be improved.

The position of the non-contact non-contact shaft vibrometer 15 is limited to the vicinity of the upper hydrostatic bearing 5E. For this reason, the number of non-contact non-contact shaft vibrometers can be reduced from two to one, and the cost can be reduced including accessories.

Further, since there is no sensor cable between the sensor and the head amplifier, the instrumentation is simplified,
Since the connection portion is also eliminated, connection failures and the like are eliminated, and the head amplifier box conventionally fixed to the pump cover, the outer wall of the motor casing, etc. with bolts and the like is eliminated, so that the ease of handling and the mounting workability are improved. In addition, when the pump is inserted into a liquid pumping tube, a pot, or the like, the pump is prevented from coming into contact with the protruding projections to cause damage.

In the above embodiment, the immersion pump device for a liquefied gas tank has been described as an example. However, in the case of another type of liquefied gas pump device (for example, a pot type liquefied gas pump in which a pump is housed in a suction casing) Of course, it can be applied.

Further, the present invention is effective not only for liquefied gas but also for pumps handling low-temperature liquids.

[0031]

As described above, according to the present invention, the following effects can be obtained.

By integrating the sensor and the head amplifier with a submerged non-contact shaft vibration meter for measuring the shaft vibration of a liquefied gas pump device having a hydrostatic bearing, the temperature characteristics are improved for the same temperature environment. Also, since there is no sensor cable between the sensor and the head amplifier, the influence of external noise is reduced, so that the reliability is improved.

Further, the elimination of the connection portion of the sensor cable between the sensor and the head amplifier simplifies instrumentation, eliminates connection failures and the like, and eliminates the head amplifier box, thereby improving ease of handling and mounting workability. improves.

Furthermore, when the pump is inserted into a liquid pumping tube, a pot, or the like, the pump does not come into contact with the protruding projections to cause damage, and the reliability of the submerged non-contact vibrometer is improved. Long-term stable operation of the gas pump can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a liquefied gas pump device according to the present invention.

FIG. 2 is a whirling mode diagram of a rotary shaft of a liquefied gas pump device.

FIG. 3 is an enlarged view of a part of a non-contact shaft vibration meter with built-in amplifier in the embodiment of FIG. 1;

FIG. 4 is an output characteristic diagram with respect to a temperature change in the embodiment of FIG. 1;

FIG. 5 is an overall view of a conventional immersion pump device for a liquefied gas tank.

FIG. 6 is a sectional view of a conventional liquefied gas pump device.

FIG. 7 is a graph showing the output characteristics of a conventional non-contact non-contact shaft vibrometer against a temperature change.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquefied gas tank, 1a ... Tank ceiling plate, 2 ... Lifting pipe, 3 ... Suction valve, 4 ... Seat surface, 5 ... Liquefied gas pump body, 5A ... Rotary shaft, 5B ... Inducer, 5C ... Impeller, 5D: Submerged motor rotor, 5E, 5F, 5G: Static pressure bearing, 5H, 5I: Auxiliary ball bearing, 5J: Balance disk, 5K: Pump cover, 6: Discharge port, 7: Head plate, 8: Lifting wire, 9 ... power supply cable, 10 ... hoisting machine, 11 ... discharge pipe, 12A12B ... submerged non-contact shaft vibration meter, 13 ... head amplifier, 14 ... head amplifier box, 15 ... submerged non-contact shaft vibration meter, 15A ... metal case , 16 ... Connector.

Claims (2)

[Claims] 1. A liquefied gas pump device comprising a hydrostatic bearing and a submerged non-contact shaft vibrometer disposed near the hydrostatic bearing for detecting vibration of a rotating shaft, wherein the submerged non-contact shaft vibrometer is provided. A liquefied gas pump device comprising a sensor and a head amplifier for amplifying an output voltage of the sensor. 2. A liquefied gas pump device according to claim 1, wherein the non-contact shaft vibrometer having a built-in sensor and a head amplifier for amplifying the output voltage of the sensor has an uppermost static pressure. A liquefied gas pump device, which is disposed on a bearing.