JP3566446B2 - Submersible pump device for liquefied gas tank, displacement detection device for rotating shaft - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a submerged pump device for a liquefied gas tank and a displacement detection device for a rotary shaft thereof.
[0002]
[Prior art]
A tank-incorporated submersible pump device used in a liquefied gas tank for storing a liquefied gas such as liquefied natural gas is generally arranged in a liquid pumping pipe suspended in the liquefied gas tank. Further, in such a submerged pump device for a liquefied gas tank, the pump supports an unbalanced axial thrust in the pump generated during an excessive flow rate operation until the pump fills the pumping pipe, reducing the load on the bearing and reducing the bearing load. In order to extend the life, a so-called axial thrust magnetic bearing is employed.
[0003]
Here, such a conventional immersion pump device for a liquefied gas tank will be described with reference to FIGS. First, FIG. 5 is a piping diagram of a liquefied gas tank including a conventional liquefied gas tank submersion pump device, and FIG. 6 is an enlarged sectional view of the liquefied gas tank submersion pump device portion of FIG.
[0004]
First, as shown in FIG. 5, a liquefied gas tank submerged pump device includes a plurality of pumping pipes 2 suspended in a liquefied gas tank 1, a suction valve 3 attached to a lower end of the pumping pipe 2, A submerged pump main body 5 disposed above the suction valve 3 and in the liquid pumping pipe 2, and via a discharge pipe 10 and a check valve 11, a liquefied gas collecting pipe (mother pipe). 14.
[0005]
The details of the immersion pump device for a liquefied gas tank will be further described with reference to FIG. Also in this figure, reference numeral 1 denotes a liquefied gas tank, reference numeral 1a denotes a ceiling plate of the gas tank 1, and reference numeral 2 denotes a liquid pumping pipe suspended in the 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 the submerged pump main body 5 is installed on a seat surface 21 of the suction valve 3. A head plate 2a provided with a pump lifting mechanism is provided at the top of these pumping tubes 2. Reference numeral 4 in the figure denotes a lifting wire for lifting the submerged pump main body 5. Reference numeral 12 denotes a plurality of discharge ports provided on the outer periphery of the submerged pump main body 5, reference numeral 17 denotes a power supply cable, and reference numeral 30 denotes a hoist.
[0006]
The submerged pump main body 5 is, for example, 50 m deep from the head plate 2a to the inside of the pumping pipe 2 vertically suspended from the ceiling plate 1a of the liquefied gas tank 1 by the lifting wire 4. It is hung to the extent, and it is seated on the seat surface 21 below the pumping pipe 2 and installed.
[0007]
Power is supplied to the submerged pump main body 5 by a power supply cable 17. When the operation of the pump is started, the liquefied gas is sucked from the suction valve 3, pressurized, and discharged from the discharge port 12. As shown by an arrow in the drawing, the liquid is raised in the liquid pumping pipe 2 and sent out to the discharge pipe 10. Generally, a plurality of such liquefied gas tank submerged pumping devices are installed in the liquefied gas tank 1 as shown in FIG.
[0008]
In such a submerged pump device for a liquefied gas tank, when the submerged pump main body 5 stops operating, the liquefied gas remaining in the liquid pumping pipe 2 flows back through a discharge port 12 provided inside the pump, and is lifted. The liquid is returned into the liquefied gas tank 1 from the suction valve 3 provided at the bottom of the liquid pipe 2. The liquid level of the liquefied gas in the pumping pipe 2 drops to the same level as the liquid level in the tank 1. Therefore, when the submerged pump main body 5 is restarted, the operation in a state in which the discharge pressure is not ensured is continued until the liquid pumping tube 2 is filled with the liquefied gas. The operating time spans several minutes.
[0009]
On the other hand, as a submerged pump for a liquefied gas tank according to the prior art, for example, as described in JP-A-1-301990, a motor is housed in a casing of a vertical shaft pump, and a shaft and a blade of the pump are provided. The car was rotated, and a shaft having a balance disk as an axial thrust balance device fixed to the upper part of the impeller, and a hydrostatic bearing in the upper, middle and lower bearings, and auxiliary ball bearings were further mounted in the middle and upper parts. Things are already known.
[0010]
That is, according to the bearing structure of the related art, the hydrostatic bearings are arranged in the upper, middle, and lower bearings, and the ball bearings serve only an auxiliary role. It is designed to be supported by bearings. Also, with respect to the axial load, the thrust force applied to the auxiliary ball bearings during normal operation of the pump (at the time of predetermined discharge pressure of the pump) is reduced to zero by the axial thrust (hereinafter, thrust force) balance device by the balance disk. It had the structure to make.
[0011]
In particular, when the size of the pump is increased and the thrust force composed of the weight of the rotating shaft system of the pump and the fluid force acting on the impeller tends to increase, for example, Japanese Patent Application No. 6-114795 has already proposed this. As shown in the figure, the single-sided suction type active axial magnetic bearing is provided, and the axial magnetic bearing is maintained for several minutes until the pumping pipe 2 is filled with the liquefied gas liquid and the predetermined discharge pressure is generated. , The thrust load of the ball bearing is eliminated, and a submerged pump having a long bearing life can be obtained.
[0012]
[Problems to be solved by the invention]
However, in the above-mentioned prior art, the following problems have been encountered with the increase in size of the pump, particularly when the above-mentioned one-sided suction type active axial magnetic bearing is provided. First, when equipped with such an axial magnetic bearing, a so-called displacement sensor is provided in order to detect the displacement that is the vertical position of the pump rotating shaft.However, in the liquefied gas tank submersible pump device, the displacement sensor is The submersion pump is installed inside the submerged pump, that is, in the liquid at a cryogenic temperature (-140 ° C. to -190 ° C.). Therefore, even if the temperature characteristics of the displacement sensor are compensated, the temperature characteristics of electronic components such as transistors constituting the sensor are not clear, and thus the displacement sensor is lacking in reliability. That is, such a displacement sensor is usually composed of a plurality of electronic components, but it is difficult to individually examine the characteristics of such electronic components at cryogenic temperatures. Examining the characteristics at a low temperature also causes a decrease in the yield as a sensor, which leads to an increase in the price of the entire device.
[0013]
On the other hand, when the above-mentioned one-sided suction type active axial magnetic bearing is equipped with the increase in size of the pump, it is particularly necessary to accurately understand the characteristics of the displacement sensor that detects the vertical position of the pump rotating shaft. Since a large downward thrust force sometimes acts, the life of the axial magnetic bearing is shortened and its reliability is also lacking.
[0014]
In view of the above, in the present invention, in consideration of the above-described problems in the related art, in particular, a magnetic bearing suitable for a submerged pump device for a liquefied gas tank equipped with a one-sided suction type active axial magnetic bearing accompanying an increase in size of a pump is provided. The present invention provides a structure of a submerged pump device for a liquefied gas tank, and a displacement detection device of a rotary shaft in a submerged pump device for a liquefied gas tank equipped with a magnetic bearing, which is suitable for detecting a rotary shaft in such a device. Aim.
[0015]
[Means for Solving the Problems]
The present invention provides a submerged pump device for a liquefied gas tank in which a thrust bearing that supports a rotating shaft that connects a motor and an impeller is formed of a magnetic bearing, wherein a displacement sensor that detects displacement of the rotating shaft is provided. The processing circuit for processing the output signal transmitted from the Hall element is configured in the atmosphere while being configured by the Hall element. A submersible pump device for a liquefied gas tank, characterized in that the accuracy is improved and the reliability is improved in an extremely low temperature environment in a liquefied gas, thereby improving the reliability.
[0016]
Further, the present invention is a rotary shaft displacement detection device for connecting a motor and an impeller of a submerged pump device for a liquefied gas tank and detecting a displacement of a rotary shaft whose thrust is supported by a magnetic bearing, A displacement detection device for a rotating shaft, comprising: a hall element that is arranged to face an upper end surface of the rotating shaft via a slit and outputs a voltage signal corresponding to the amount of the slit, is disclosed.
[0017]
Further, the present invention relates to a rotary shaft displacement detecting device for connecting a motor of a submerged pump for a liquefied gas tank and an impeller, and detecting a displacement of a rotary shaft supported by a thrust magnetic bearing, A detection coil having an inductance that is arranged opposite to the upper end face of the device with a gap therebetween and changes in accordance with the amount of the gap due to eddy current, and a semiconductor circuit element for processing a displacement signal from the detection coil And a means for maintaining the temperature of the semiconductor circuit element at a temperature acceptable for the temperature characteristics of the electronic components constituting the semiconductor circuit element. A detection device is disclosed.
[0018]
That is, according to the present invention, in the liquefied gas tank submerged pump device which is used at a cryogenic temperature in the liquefied gas tank and has a thrust bearing for supporting the pump rotating shaft constituted by a magnetic bearing, power is supplied to the magnetic bearing. A displacement sensor that detects the displacement of the rotating shaft to enable high-precision current control The pole By using a Hall element whose low-temperature resistance is compensated even at low temperatures, or a displacement sensor composed of an eddy current type detection coil and a semiconductor circuit element for processing its displacement signal, etc. By providing a temperature holding means comprising a heater or the like and maintaining the temperature characteristics of the electronic components constituting the semiconductor circuit element at an acceptable temperature, the temperature resistance characteristics are highly reliable even in an extremely low temperature environment in a liquefied gas. According to the displacement sensor having such a configuration, even at a very low temperature in the liquefied gas tank, the gap between the detection unit of the displacement sensor and the rotating shaft is detected with high accuracy, Indirectly measuring the axial displacement of the pump rotation shaft, furthermore, the current to be supplied to the magnetic bearing supporting the thrust force, the gap is constant. A highly reliable liquefied gas tank that actively controls the magnetic bearing and can support the thrust force consisting of the weight of the rotating shaft system and the fluid force acting on the impeller, thereby shortening the life of the axial magnetic bearing. It is possible to provide a submersible pump device for use.
[0019]
More specifically, according to the configuration of the embodiment of the present invention described in detail below, the submerged pump main body of the submerged pump device for a liquefied gas tank has a one-sided suction type active axial thrust generated at the time of starting the pump. A magnetic bearing is provided, and at the time of starting the submerged pump, if the magnetic bearing is activated before starting, the attractive force of the magnetic bearing causes the ferromagnetic rotating system to float, and during operation after starting, displacement occurs. The sensor detects the gap δ between the detection unit of the displacement sensor and the pump rotation axis, indirectly measures the axial displacement of the pump rotation axis, and sets the magnetic bearing so that the gap δ becomes constant. Is actively controlled to support a thrust force consisting of the own weight of the rotating shaft system and a fluid force acting on the impeller.
[0020]
According to the present invention, the displacement sensor for controlling the one-sided suction type active axial thrust magnetic bearing includes a magnetic field generating coil, bundle Detection hole Elementary The magnetic flux detection Hall element is compensated for low-temperature resistance, and the electronic circuit part consisting of the detection circuit and the amplification circuit is By installing the electronic component in an environment that is optimal for the temperature characteristics of the electronic component itself, it is possible to detect the gap δ with high reliability and high accuracy even at extremely low temperatures, and as a result, A highly accurate control of a one-sided suction type active axial thrust magnetic bearing in a submerged pump device is enabled.
[0021]
Further, according to the present invention, as a displacement sensor of another structure, a displacement detection coil, an electronic circuit including a detection circuit and an amplification circuit are integrated and housed in a sealed case, and further, a heater is installed on the outer periphery thereof. With explosion-proof construction. In a displacement sensor having such a structure, a heater is installed around a case that houses the sensor components to maintain a constant temperature, thereby making the environment optimal for the temperature characteristics of a single electronic component, or a cause of a temperature drift of a detection signal. By reducing the temperature change, it becomes possible to detect the gap δ with high accuracy, and thus the one-sided suction type active axial thrust magnetic bearing in the immersion pump device for a liquefied gas tank has high reliability and high reliability. Accurate control becomes possible.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 2 shows a sectional view of one embodiment of the immersion pump device for a liquefied gas tank according to the present invention. Also in this sectional view, reference numeral 1 denotes a liquefied gas tank, and reference numeral 1a denotes a ceiling plate of the gas tank 1. Reference numeral 2 denotes a pumping pipe suspended in the 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 the submerged pump main body 5 is installed on a seat surface 21 of the suction valve 3. A head plate 2a provided with a pump lifting mechanism is provided at the top of these pumping tubes 2. Reference numeral 4 in the figure denotes a lifting wire for lifting the submerged pump main body 5. Reference numeral 12 denotes a plurality of discharge ports provided on the outer periphery of the submerged pump main body 5, reference numeral 17 denotes a power supply cable, reference numeral 30 denotes a hoist, reference numeral 50 denotes a magnetic bearing control device, and reference numeral 42 denotes a magnetic bearing control device. Denotes a cable take-out terminal for a magnetic bearing.
[0023]
The submerged pump main body 5 is, for example, 50 m deep from the head plate 2a to the inside of the pumping pipe 2 vertically suspended from the ceiling plate 1a of the liquefied gas tank 1 by the lifting wire 4. It is hung to the extent, and it is seated on the seat surface 21 below the pumping pipe 2 and installed. Power is supplied to the submerged pump main body 5 by a power supply cable 17. When the operation of the pump is started, the liquefied gas is sucked from the suction valve 3 and discharged from the discharge port 12 to be pumped. The pressure is increased in the pipe 2, and as shown by the arrow in the figure, the liquid rises in the liquid pumping pipe 2 and is sent to the discharge pipe 10. In general, a plurality of such liquefied gas tank submerged pumping devices are installed in the liquefied gas tank 1.
[0024]
In such a submerged pump device for a liquefied gas tank, when the submerged pump main body 5 stops operating, the liquefied gas remaining in the liquid pumping pipe 2 flows back through a discharge port 12 provided inside the pump, and is lifted. The liquid is returned into the liquefied gas tank 1 from the suction valve 3 provided at the bottom of the liquid pipe 2. The liquid level of the liquefied gas in the pumping pipe 2 drops to the same level as the liquid level in the tank 1. Therefore, when the submerged pump main body 5 is restarted, the operation in a state in which the discharge pressure is not ensured is continued until the liquid pumping tube 2 is filled with the liquefied gas. The operation time extends over several minutes, as in the above-mentioned prior art.
[0025]
FIG. 3 shows an enlarged cross section of the submerged pump main body 5 of the liquefied gas tank submerged pump device shown in FIG. 2 in particular. Is a pump rotation shaft which is a rotation shaft rotatably attached to the case, and 5B is an inducer. 5C is a plurality of impellers, 5D is a submerged motor rotor, 5E, 5F, and 5G are self-liquid lubricated hydrostatic bearings, 5H and 5I are catching ball bearings, and 5J is a balance disk. 5K indicates an electromagnet of a thrust magnetic bearing portion, 5L indicates a ferromagnetic rotor, 5M indicates a magnetic bearing terminal block, 5N indicates a displacement sensor, and 18 indicates a power supply cable for a magnetic bearing and a displacement sensor signal cable. .
[0026]
As shown in FIG. 2, the structure of the submerged pump main body 5 is such that an inducer 5B, a plurality of impellers 5C, and a submerged motor rotor 5D fixed to a pump rotating shaft 5A for improving suction performance are fixed. These are integrated structures, and rotate integrally. The pump rotating shaft 5A, the inducer 5B, the plurality of impellers 5C, and the submerged motor rotor 5D are radially supported by self-liquid lubricated hydrostatic bearings 5E, 5F, and 5G. On the other hand, in the axial direction, the axial thrust is self-balanced by a thrust balancing 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 No thrust force is applied.
[0027]
On the other hand, a suction-type active axial magnetic bearing is disposed at the uppermost end of the pump rotating shaft 5A. That is, the suction-type active axial magnetic bearing includes an electromagnet 5K of a thrust magnetic bearing, a ferromagnetic rotor. 5L. Then, an exciting current controlled by the magnetic bearing control device 50 flows through the power supply cable 18 to the electromagnet 5K of the thrust magnetic bearing portion.
[0028]
In the suction-type active axial magnetic bearing having such a configuration, when the submerged pump main body 5 is started, since the inside of the liquid pumping tube 2 is empty, the pump is in a large discharge operation state, and the axial thrust balance mechanism is operated. Since it disappears, the own weight of the pump rotating body and the total thrust of the fluid force acting on the impeller 5C and the balance disk 5J act vertically downward. Accordingly, the magnetic bearing electromagnet 5K is provided only on one side and is controlled by the electromagnet so that the rotor 5L made of a ferromagnetic material can be pulled upward by an attractive electromagnetic force corresponding to a thrust force acting downward. . Since the attracting electromagnetic force is affected by the distance between the surfaces of the magnetic bearing electromagnet 5K and the rotor 5L, that is, δ, in order to indirectly detect this distance δ, the pump rotating shaft 5A A displacement sensor 5N for detecting a vertical position is provided.
[0029]
FIG. 1 shows an upper end portion of the pump shaft 5A, which is a rotating shaft, and a displacement sensor 5N for detecting the vertical position of the pump rotating shaft. In this figure, reference numeral 101 denotes an electromagnet coil for generating a magnetic field, reference numeral 102 denotes a Hall element for detecting a magnetic flux density, and reference numeral 103 denotes a sensor made of a ferromagnetic material attached to the upper end of the pump shaft 5A. Reference numeral 108 denotes a connector for the sensor.
[0030]
The displacement sensor 5N shown in FIG. 1 changes the gap δ between the displacement sensor 5N and the upper end of the pump shaft 5A, that is, between the magnetic field generating electromagnet coil 101 and the ferromagnetic sensor target 103. The accompanying change in the magnetic flux density is detected by the Hall element 102, and the detected change in the magnetic flux density is transmitted as a displacement signal. Generally, when a constant current flows through the electromagnet coil 101 and the ferromagnetic material is close to the magnet coil 101, the magnetic flux density between the electromagnet coil 101 and the ferromagnetic sensor target 103 and the gap δ are inversely proportional. In a relationship. The Hall voltage, which is the output from the Hall element 102, is proportional to the magnetic flux density.
[0031]
Now, when the electromagnet coil 101 for generating a magnetic field is energized and the pump rotating shaft 5A moves upward in the figure and the gap δ between the electromagnet coil 101 for generating a magnetic field and the target 103 for a ferromagnetic sensor becomes small, a magnetic field is generated. Magnetic flux density between the electromagnet coil 101 and the ferromagnetic sensor target 103 increases. When the magnetic flux density is increased in this manner, the Hall element 102 transmits an output voltage corresponding to the increased magnetic flux density, and the magnetic bearing control device 50 that has received the signal reduces the exciting current of the electromagnet 5K of the magnetic bearing. The suction electromagnetic force becomes small, and the pump rotating shaft 5A moves downward in the figure.
[0032]
When the rotating shaft 5A moves downward in the figure and the gap δ between the magnetic field generating electromagnet coil 101 and the ferromagnetic sensor target 103 increases, the magnetic field generating electromagnet coil 101 and the ferromagnetic sensor Magnetic flux density with the target 103 for use becomes small. Therefore, when the magnetic flux density decreases, the Hall element 102 transmits an output voltage corresponding thereto, and the magnetic bearing control device 50 receiving the signal increases the exciting current of the electromagnet 5K of the magnetic bearing, thereby reducing the attractive electromagnetic force. The pump rotation shaft 5A moves upward in the figure. In this way, the gap δ is controlled to a predetermined state so that the residual thrust force is not applied to the auxiliary ball bearings 5H and 5I.
[0033]
Note that the magnetic flux detecting Hall element used for detecting the gap δ in the above embodiment is generally compensated for its low-temperature resistance characteristics. An electronic circuit section including a circuit is taken out of the liquefied gas tank 1 and installed in the atmosphere, and is installed in an environment that is optimal for the temperature characteristics of a single electronic component, thereby obtaining a highly reliable and accurate displacement sensor. It becomes possible. That is, by using such a high-precision displacement sensor, the gap δ between the magnetic field generating electromagnet coil 101 and the ferromagnetic sensor target 103 can be detected with high accuracy. As a result, the magnetic bearing control device 50 controls the above-mentioned gap δ with high accuracy even at the time of starting the pump, thereby shortening the life of the axial magnetic bearing and having a highly reliable liquefied gas tank submersible. It becomes possible to control the one-sided suction type active axial thrust magnetic bearing in the submerged pump device.
[0034]
FIG. 4 shows a structure of a displacement sensor 5N of a submerged pump device for a liquefied gas tank according to another embodiment of the present invention. The displacement sensor 5N is configured by an eddy current method. In the illustrated structure, reference numeral 104 denotes a displacement detection coil, reference numeral 105 denotes a semiconductor element including a detection circuit and a modulation circuit for a displacement signal, and reference numeral 106 denotes an explosion-proof structure. The applied heater and reference numeral 107 indicate a thermocouple for temperature control. As shown in the figure, a detection coil 104 that detects displacement as a change in inductance, and a semiconductor circuit element 105 including a detection circuit, a modulation circuit, an amplification circuit, and the like that constitute a processing circuit for a displacement signal of the detection coil include: The heater 107 and a thermocouple 109 for temperature control are provided in the outer case 110 so as to surround the inner case 106.
[0035]
Also, in the liquefied gas tank submersible pump device of FIG. 4, the submerged pump main body 5 is provided with a seat provided at the bottom of the liquid pumping pipe 2 suspended in the liquefied gas tank 1 as shown in FIG. It is placed sitting on the surface 21. On the other hand, a power supply cable of a magnetic bearing and a displacement sensor signal cable 18 are provided on a head cover 2a at the uppermost end of the pumping pipe 2 via a magnetic bearing terminal block 5M in FIG. The cable 18 may be connected to a magnetic bearing control device 50 installed outside the liquefied gas tank 1 via the terminal terminal so as to be separated from the liquefied gas tank 1. This is the same as the above embodiment.
[0036]
Next, the control of the attraction electromagnetic force of the electromagnet 5K of the magnetic bearing in the magnetic bearing control device 50 by the output of the displacement sensor 5N having the above configuration will be described with reference to FIG.
Now, when the pump rotation shaft 5A moves upward in the drawing and the gap δ between the displacement sensor 5N, that is, the detection coil 104 and the pump rotation shaft 5A becomes small, the detection coil 104 rotates the pump rotation shaft 5A. When the eddy current generated on the end surface 5S of the shaft 5A in the radial direction of the shaft becomes large and the inductance of the detection coil 104 becomes large, the magnetic bearing control device 50 makes the exciting current of the electromagnet 5K of the magnetic bearing small, and the attraction electromagnetic force becomes small. As a result, the pump rotation shaft 5A moves downward in the figure.
[0037]
On the other hand, when the pump rotation shaft 5A moves downward in the drawing and the gap δ between the detection coil 104 and the pump rotation shaft 5A becomes large, the detection coil 104 becomes an end surface of the pump rotation shaft 5A in the axial radial direction. The eddy current generated in 5S decreases, and the inductance of the detection coil 104 decreases. As described above, when the inductance of the detection coil 104 is reduced, the magnetic bearing control device 50 increases the exciting current supplied to the electromagnet 5K of the magnetic bearing, and increases the attraction electromagnetic force. Moves upward in the figure. In this manner, the gap δ is controlled to a predetermined state so that the residual thrust force is not applied to the auxiliary ball bearings 5H and 5I.
[0038]
Further, as described above, the heater 107 is installed on the outer periphery of the storage case in which the semiconductor circuit element 105 including the detection circuit, the modulation circuit, the amplification circuit, etc., which is a processing circuit for the displacement signal of the detection coil 104, is stored. In addition, the thermocouple 109 is controlled so that the temperature characteristics of the semiconductor circuit element 105, which is an electronic component, are maintained at an allowable constant temperature. Needless to say, this displacement sensor has a so-called explosion-proof structure. Further, since the displacement sensor 5N is installed inside the submerged pump main body 5 and is exposed to a cryogenic environment, in order to protect the IC, which is a semiconductor circuit element therein, from dew condensation or thermal deformation of the element, For example, it is molded with resin. Then, by using a magnetic bearing incorporating such a displacement sensor 5N, a highly reliable and highly accurate displacement sensor can be obtained. That is, by using such a high-precision displacement sensor, the gap δ between the displacement coil 104 and the upper end of the pump rotating shaft 5A can be detected with high accuracy. Even when the pump is started, the gap δ is controlled with high precision, thereby shortening the service life of the axial magnetic bearing, and having a high reliability, a one-sided suction type active axial type in a submerged pump device for a liquefied gas tank. Control of the thrust magnetic bearing becomes possible. The structure of the displacement sensor described above is not limited to the above-described structure, and various other types of sensors that take measures against low-temperature resistance that are acceptable for electronic components constituting the sensor can be considered.
[0039]
【The invention's effect】
As described in detail above, according to the liquefied gas tank submerged pump device provided with the magnetic bearing according to the present invention, and the device for detecting the rotating shaft in such a device, even in a cryogenic environment in the liquefied gas tank, The displacement sensor makes it possible to detect the displacement of the vertical position of the pump rotating shaft with high accuracy.Thus, the detection output reliably reduces the thrust force acting on the bearing when the pump is started, and extends the life of the bearing. It is possible to provide a practically excellent submerged pump device for a liquefied gas tank, which makes it possible to improve the reliability of the device and make the bearing portion of the device maintenance-free. Demonstrate.
[Brief description of the drawings]
FIG. 1 is a partially enlarged sectional view of a displacement sensor in an embodiment of a submerged pump for a liquefied gas tank according to the present invention.
FIG. 2 is a side sectional view of the entire immersion pump device for a liquefied gas tank.
FIG. 3 is a sectional view of a submerged pump main body in the submerged pump device for a liquefied gas tank shown in FIG. 2;
FIG. 4 is a partially enlarged sectional view of a displacement sensor part in another embodiment of the liquefied gas tank submersible pump device according to the present invention.
FIG. 5 is a liquefied gas tank piping system diagram including a liquefied gas tank submersible pump device according to the prior art.
FIG. 6 is a sectional view of the submerged pump device for a liquefied gas tank of FIG. 5;
[Explanation of symbols]
1 liquefied gas tank
1a Tank ceiling plate
2 Pumping pipe
2a Head plate
3 Suction valve
4 Lifting wire
5 Submersible pump body
5A pump shaft
5B inducer
5C impeller
5D motor rotor
5E, 5F, 5G
5H, 5I auxiliary ball bearing
5J balance disc
Electromagnet of 5K thrust magnetic bearing
5L ferromagnetic rotor
5M magnetic bearing terminal block
5N displacement sensor
5S Surface where eddy current is generated
10 Discharge pipe
11 Check valve
12 Pump outlet
14 Liquefied gas collecting pipe (mother pipe)
17 Power supply cable
18 Power supply cable for magnetic bearing cable and signal cable for displacement sensor
21 Seating surface of submerged pump
30 hoist
42 Extraction terminal terminal for magnetic bearing cable
50 Magnetic bearing control device
101 Electromagnetic coil for generating magnetic field
102 Hall element
103 Target for ferromagnetic sensor
104 displacement coil
105 semiconductor circuit element
106 inner case
107 heater
108 Connector
109 thermocouple
110 Outer case

Claims (10)

In a submerged pump device for a liquefied gas tank in which a thrust bearing that supports a rotating shaft that connects a motor and an impeller is formed by a magnetic bearing, a displacement sensor that detects displacement of the rotating shaft is provided under a cryogenic environment in a liquefied gas. A submerged pump device for a liquefied gas tank, characterized in that the submersible pump device for a liquefied gas tank comprises a normally operating Hall element and a processing circuit for processing an output signal transmitted from the Hall element . 2. The immersion pump device for a liquefied gas tank according to claim 1 , further comprising: an electromagnetic coil for generating a magnetic field adjacent to the Hall element, and a ferromagnetic material provided at an upper end of the rotating shaft. A submerged pump device for a liquefied gas tank to which a target is attached . In a submersible pump device for a liquefied gas tank, wherein a thrust bearing for supporting a rotating shaft connecting a motor and an impeller is formed by a magnetic bearing, a displacement sensor for detecting displacement of the rotating shaft is provided, and the displacement sensor is a displacement coil. And a semiconductor circuit element for processing a displacement signal from the displacement coil, and further for maintaining the temperature of the displacement sensor at a temperature that is acceptable for the temperature characteristics of the electronic components constituting the semiconductor circuit element. provided with a temperature holding means, the temperature holding means, the displacement sensor that liquefied gas tank for submersible pump apparatus according to claim which is constituted by a heater arranged妨爆structure around. 4. A submersible pump device for a liquefied gas tank according to claim 3 , wherein said temperature holding means further comprises means for detecting a temperature in said displacement sensor. . 5. The submersible pump device for a liquefied gas tank according to claim 4, wherein the temperature detecting means in the displacement sensor is constituted by a thermocouple . A displacement detection device for a rotary shaft for connecting a motor of an immersion pump device for a liquefied gas tank and an impeller, and detecting a displacement of a rotary shaft supported by a magnetic bearing for a thrust, wherein an upper end surface of the rotary shaft is provided. A displacement detection device for a rotating shaft, comprising: a Hall element that is disposed to face the device via a slit and outputs a voltage signal corresponding to the amount of the slit. 7. The rotating shaft detecting device according to claim 6 , further comprising: a magnetic field generating electromagnet coil adjacent to the Hall element, and a sensor target made of a ferromagnetic material at an upper end of the rotating shaft. A displacement detection device for a rotating shaft, wherein the displacement detection device is mounted . 8. The displacement detection device for a rotating shaft according to claim 7, wherein a processing circuit for processing a voltage signal transmitted from the Hall element is further installed in the atmosphere . A displacement detection device for a rotary shaft for connecting a motor of a submerged pump for a liquefied gas tank and an impeller and detecting a displacement of a rotary shaft supported by a thrust magnetic bearing, wherein a thin end is provided on an upper end surface of the rotary shaft. A detection coil having an inductance that is arranged to face through the gap and changes in accordance with the amount of the gap by the eddy current, and a semiconductor circuit element for processing a displacement signal from the detection coil; And a means for maintaining the temperature of the semiconductor circuit element at a temperature at which the temperature characteristics of the electronic components constituting the semiconductor circuit element are permissible . 10. The rotary shaft displacement detecting device according to claim 9 , wherein the temperature holding means is constituted by an explosion-proof heater arranged around the semiconductor circuit element. .

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