JPH08296586A - Vertical shaft type submerged pump device for liquified gas tank - Google Patents

Abstract

PURPOSE: To increase the strength of a bearing for supporting a pump shaft in association with the displacement enlargement of a pump and the bore enlargement of a liquid lifting pipe. CONSTITUTION: The center bearing 15 of a submerged type vertical shaft pump is detached from the support of a pump shaft 12 by the action of a balancer 17 during the normal operation of the pump. Instead a static pressure bearing 19B supports the pump shaft 12. At the start time, not during the normal operation of the pump, thrust load is applied to the center bearing 15, and the burden of load becomes large, so that the service life of the bearing is shortened. As the center bearing 15, two single-row deep groove type ball bearings 15a, 15b are therefore arranged vertically along the longitudinal direction of the shaft 12, and a ring spacer 15c is interposed between them so as to form the deep groove type ball bearing 15 arranged in double rows. Load F is dispersed equally to two single-row deep groove type ball bearings 15a, 15b, so that the strength of the center bearing 15 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submerged pump device for a liquefied gas tank, and more particularly to a submerged motor type submerged pump device for a liquefied gas tank for storing a liquefied gas such as liquefied natural gas.

[0002]

2. Description of the Related Art A conventional submerged pump device for a liquefied gas tank disclosed in Japanese Patent Laid-Open No. 1-301990 is shown in FIG.
Shown in In the liquefied gas tank 1, a lift pipe 2 is vertically formed so as to hang down. The pump 5 is inserted into the pumping pipe 2 from the outside and mounted. This includes head plate 8 to wire 4
Suspend the pump 5 vertically (height: 10 m),
This is achieved by lowering the wire 4 and seating the pump 5 on the seat surface 6 below the pumping pipe 2. The pump 5 includes an impeller (impeller) section 5B for increasing the pressure, and a rotary drive section (rotational drive is performed by, for example, a motor) 5A connected to a shaft of the pump and rotating the shaft. The seat surface 6 leads to the suction port 3,
The pump 5 boosts the pressure of the liquefied gas from the suction valve 3A by the pump 5 and discharges it from a plurality of discharge passages 5P provided on the discharge side of the impeller portion 5B. The discharged liquefied gas flows out of the passage 5P, flows upward in the pumping pipe 2, and is discharged from the discharge pipe 7.
When the pump 5 is started, the pump 5 operates at a discharge pressure considerably lower than a predetermined discharge pressure for several minutes until the discharge pipe is filled with the discharge liquid. This is because these few minutes require only a slight discharge pressure to push up the liquid. After this, the normal operating state is entered.

The pump 5 shown in FIG. 7 is generally called a vertical shaft type pump. A conventional example of this vertical shaft pump is Japanese Patent Publication No. 61-.
There is number 5558. In such a vertical shaft pump, a ball bearing (for example, a single-row deep groove type ball bearing) that supports the rotary shaft is provided near the position where the rotary drive unit 5B is arranged and the position where the impeller unit 5A is arranged. In order to prevent the bearing from being damaged by a thrust load during operation, a shaft thrust balancer including a balance disk or the like is provided near the bearing. The ball bearing works as a bearing for the rotating shaft when starting and stopping the pump. On the other hand, the shaft thrust balancer is configured so that the static pressure bearing works in place of the ball bearing during normal operation without starting / stopping. For this purpose, a static pressure bearing may be provided so that the static pressure bearing functions as a bearing instead of the ball bearing during operation. As a shaft thrust balancer, there is Japanese Patent Publication No. 58-25876.

As described above, in the vertical shaft pump of Japanese Patent Publication No. 61-5558, an axial thrust balancer is provided to reduce the thrust load applied to the ball bearings to zero during pump operation. Only radial load acts on the bearing. However, since the radial load is mainly received by the hydrostatic bearing, the ball bearing essentially only plays an auxiliary role. However, in reality, the axial thrust balancer
Because the pump functions under the condition that the discharge pressure is generated, the ball bearing has a large thrust load such as the weight of the pump rotor and the downward thrust of the impeller for several minutes until the discharge liquid fills the pumping pipe. Is loaded.

When the pump is relatively small and the pump has a small diameter, the liquid filling time is short and the thrust balancer works immediately. However, the pump has a large capacity and the diameter of the pump is increased. In this case, the time it takes for the liquid to fill the pumping pipe after starting the pump is further extended, and the thrust load is also added to the ball bearing for a longer time, which significantly shortens the bearing life. I could not hope for long-term stable driving. Therefore, conventionally, a single-row deep groove type ball bearing has been used as the bearing, but it has become necessary to deal with the above problems.

[0006]

As described above,
The single-row deep groove type ball bearing that constitutes the bearing in the conventional submerged pump device for a liquefied gas tank has a structure capable of withstanding a thrust load, but has no allowance for a larger thrust load. FIG. 6 shows the system head curve immediately after starting the submersible vertical pump. The curve on the left side shows the discharge flow rate on the horizontal axis, the discharge output on the vertical axis, and how the changes from start to start, and so on. The pressurized liquefied gas is discharged from the discharge pipe 7 after about 3 minutes. The pump device on the right side is the pump 2
, A pump 5, a head plate 8 and a discharge pipe 7 are shown.

First, when the pump 5 is started, a slight discharge pressure sufficient to push up the liquid is sufficient for several minutes until the inside of the pumping pipe 2 is completely filled with the discharge liquid, and the pump 5 is considerably lower than the rated discharge pressure. It operates at the discharge pressure and operates in a large liquid volume. At the same time as the liquid level in the pumping pipe 2 gradually rises, the system head curve of the pump also changes. Liquid is pumping pipe 2
The discharge pressure reaches the rated value only when the discharge pressure is satisfied by the upper discharge pipe 20. Especially when the pump becomes large and the pumping pipe 2 has a large diameter, the time is further extended until the rated discharge pressure is reached, the axial thrust balancing device does not operate, and a large thrust load is applied to the ball bearing. It will be. When the size of the pump is increased in this way, the weight of the impeller parts such as the pump rotor and impeller increases, and a large thrust load is also applied to the ball bearing. Furthermore, due to the larger diameter of the pumping pipe, it takes time for the liquid to fill the pumping pipe and reach the specified discharge pressure after the pump starts, and it takes a long time for the thrust load to operate normally. Is loaded on the ball bearing, and there is a problem that the life of the bearing is further shortened by these.

An object of the present invention is to provide a pump device capable of extending the service life of a bearing even when the capacity of the pump is increased and the diameter of the pumping pipe is increased.

[0009]

SUMMARY OF THE INVENTION In the present invention, a double row deep groove type ball bearing is provided as a pump bearing.

[0010]

According to the present invention, the ball bearing can use the bearing radial load during the normal operation of the pump as an auxiliary function by the function of the thrust balance equilibrium device in the conventional manner, and after the pump is started, The liquid load fills the pumping pipe, reaches a predetermined discharge pressure, and the thrust load applied to the bearing before the thrust balancer operates can be dealt with by the double-row arrangement, thereby extending the life of the ball bearing.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a detailed embodiment view of a submerged pump for a liquefied gas tank and a pumping pipe, particularly a vertical sectional view thereof. In the figure,
The same reference numerals as those in FIG. 7 are equivalent to those of the conventional technique.
Although not shown in FIG. 1, it goes without saying that a liquefied gas tank, a discharge pipe and the like are present as in FIG. The submerged pump device for a liquefied gas tank of the present embodiment has a pumping pipe 2 suspended in a liquefied gas tank, and a seating surface 6 at the bottom of the pumping pipe 2.
It consists of a pump 5 and a casing 18 which are installed while being seated on.

The bottom portion 6 of the pumping pipe 2 is connected to the suction port 3, and the liquefied gas flows from the suction port 3 through the suction valve 3A into the pump 5 through the bottom portion 6. The pump 5 includes a rotary drive unit 5A provided at an upper position and an impeller unit 5 provided at a lower position.
B and a rotary shaft (shaft) 12. The rotary drive unit 5A includes a rotor (rotor) unit 9 coupled to a shaft 12 and a stationary (stator) unit 10 facing the rotor unit 9. The stationary unit 10 and the rotor unit 9 form a motor. The shaft 12 is rotated by forming and rotating the rotor unit 9.

The impeller (impeller) section 5B is composed of a plurality of impellers 13 mounted on the shaft 12 and a stage 11 mounted on the fixed side from the liquefied gas suction side to the upper side of the shaft 12. Further, a plurality of discharge holes 5P are provided above the impeller portion 5B to send the pressurized liquefied gas to the discharge passage 5Q. An upper bearing 16 is provided near the position where the shaft 12 is attached to the head plate 8 above the rotary drive unit 5A.
A lower bearing 14 is provided in the vicinity of the bottom portion 6 of the second impeller portion 5B, and further, a middle bearing 15 is provided in the vicinity of a relay portion between the impeller portion 5B and the rotation driving portion 5A, each supporting the shaft 12.
In addition, a hydrostatic bearing 19A is provided above the upper bearing 16. A shaft thrust balancer 17 is provided around and below the middle bearing 15. The axial thrust balancer 17 is a medium bearing 1
5, a cylindrical shaft sleeve 17A, a hydrostatic bearing 19B, a balance disk 17B, etc. However,
The hydrostatic bearing 19B is not included in the concept of the axial thrust balancer 17 to be precise, but it is included as a part of the balancer because it is close to the arrangement. The intermediate bearing 15 supports the shaft 12 at the time of starting / stopping. On the other hand, when the operating state is entered, the axial movement of the balance disk 17B causes the axial bearing 17A to support the intermediate bearing 15. The shaft 12 is detached and supported by the hydrostatic bearing 19B, and the support is changed from the intermediate bearing 15 to the hydrostatic bearing 19B. As a result, the axial thrust acting on the middle bearing 15 is removed.

The upper bearing 16 is a single row deep groove type ball bearing, and the middle bearing 15 is a double row deep groove type ball bearing. The lower bearing 14 uses a hydrostatic slide bearing. The reason why this static pressure slide bearing is used is to reduce the vibration at the end of the bearing. The double-row arrangement deep groove type ball bearing used for the middle bearing 15 includes, for example, upper and lower two bearings as shown in FIG.
The ball bearings are arranged in rows and form an important feature of this embodiment.
The hydrostatic bearings 19A and 19B are provided in the peripheral portions of the bearings 16 and 15, and guide the high pressure discharge liquid of the pump to form hydrostatic bearings.

FIG. 2 is a sectional view of the middle bearing 15 and the hydrostatic bearing 19B. The middle bearing 15 is a double row (upper and lower two in the figure).
Row) arranged deep groove type ball bearings, and upper and lower ball bearings 15
A ring spacer 15c having the same inner diameter as the ball bearings 15a and 15b is provided between a and 15b, and the shaft 1
Fixed to 2. Furthermore, the bearing housing 15d
A space 15e is provided between and. The provision of the space 15e serves to smoothly perform the axial movement by the action of the axial thrust balancer 17. Below the middle bearing 15, a hydrostatic bearing 19 that fulfills a bearing function by a supply liquid (arrow) is provided.
B is provided, and the radial load is mainly supported by the static pressure bearing 19B, and the middle bearing 15 has an auxiliary supporting role by the space 15e unless the shaft 12 rotates about whirling. As a result, wear of the ball bearing due to solid contact is reduced and the life of the bearing is extended. Further, the interval 15e prevents interference of the axial movement by the axial thrust balancer 17.

The structure of the deep groove type ball bearing is as follows:
In addition to the outer ring and the balls 15f, a holding means for holding the balls is required. This holding means is a holder 15g fixed with rivets 15h. The ring spacer 15c has a function of protecting the heads of the rivets from coming into contact with each other when they are arranged in a double row, and this material is made of stainless steel which is not inferior in strength even at an extremely low temperature when the motor is formed of a superconducting coil. preferable.

Regarding the thrust load in the case of double row, as shown in FIG. 3, the axial thrust load F is distributed to the upper and lower ball bearings 15a and 15b, respectively, and is F / 2.
Bearing 15, the life of the bearing 15 is further extended.
Further, if a single row deep groove type ball bearing of this double row arrangement type is used with a race of stainless steel, wear resistant steel, balls, etc., a longer bearing life can be expected.

FIG. 4 is a structural sectional view of the vicinity of the liquefied gas tank submersible pump device according to the present invention including the middle bearing. The double-groove deep groove type ball bearing 15 is sandwiched between the ring spacers 15b and integrally fixed to the shaft 12 by a tight spring, and the impeller 13 and the balance disc 17B are fixed to the shaft 12 by the tapered bush 24. It moves in the same way as the vertical movement of 12.

When the pump is operated, the pump shaft thrust acts downward and the shaft 12 moves downward. Gap 2
2 becomes large, a large amount of liquid flows in from the outer periphery of the balance disc 17B, and the pressure on the back surface of the balance disc 17B becomes smaller than the pressure on the front surface of the balance disc 17B. As a result, impeller 13 and balance disc 17B
The balance of the axial thrust acting on the shaft system including
A2) <(B1 + B2), and the upward thrust prevails and tries to move upward. Here, A1 is an upward thrust acting on the impeller A2 is a downward thrust acting on the impeller B1 is an upward thrust acting on the balance disc B1 is a downward thrust acting on the balance disc.

On the contrary, when the shaft 12 moves excessively upward and the gap 22 is closed, the balance disc 17B is closed.
Liquid does not flow in from the outer periphery, and balance disk 17B
The pressure on the back surface of is equal to the pressure on the front surface of the balance disk 17B. As a result, the axial thrust balance disk acting on the shaft system is (A1 + A2) <(B1 + B2)
And the downward thrust increases. As a result, the shaft 12 moves downward. During the above operation, the hydrostatic bearing 19 </ b> B supports the shaft 12 instead of the intermediate bearing 15.

In this way, the axial thrust force in the vertical direction is automatically balanced, but this is only the operation when the pump is at or above a predetermined discharge pressure near the rated discharge pressure.
While the pump is started and the pumping pipe 2 is filled with the liquid for several minutes, the axial thrust balancer 17 does not work and the thrust load is applied to the deep groove type ball bearing 15, but the double row arrangement (15
a, 15b) to distribute the thrust weight,
It is possible to reduce the load applied to one deep groove type ball bearing and extend the life of the bearing.

Further, it supports the shaft 12 during pump operation,
The hydrostatic bearing 19B of FIG. 4 will be described. Hydrostatic bearing 19B
During the pump operation, the high-pressure discharge liquid is sent from the vicinity of the pump discharge hole 5P through the liquid supply hole 21 and the shaft 12
For mainly supporting the load in the radial direction.

FIG. 5 is a sectional view of the vicinity of the upper bearing 16 and the hydrostatic bearing 19A. The pressurized discharge liquid is guided to the hydrostatic bearing 19A from the system passage 30 to support the shaft 12. In particular, the bearing 12 in normal operation in combination with the upper bearing 16
Support.

According to the present embodiment, by disposing the single row deep groove type ball bearings in the bearing 15 in the double row, a great thrust load is dispersed to each ball bearing immediately after the pump is started, It is possible to reduce the thrust load applied to one ball bearing and contribute to prevent the bearing life from being shortened. Also, single-row deep groove type ball bearings are arranged in multiple rows and integrally fixed to the shaft 12, and the bearing housing 1
By providing a structure with a gap of 5d, the axial movement by the thrust balance equilibrium device 17 is smoothly performed during normal pump operation, no thrust load is applied, and the radial load is combined with the hydrostatic bearing. Allows you to drive with little load.

[0025]

As described above, according to the present invention, it is possible to prevent the bearing life from being shortened due to the thrust load at the time of starting the pump, which is a drawback of the submerged pump for the liquefied gas tank, and to improve the long-term stable operation and reliability of the pump. Can be made.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of an embodiment of a double-row arrangement deep groove type ball bearing according to the present invention.

FIG. 3 is a thrust load distribution diagram of a double-row arrangement deep groove type ball bearing of the present invention.

FIG. 4 is a sectional view of an embodiment of the ball bearing and shaft thrust balancing device of the present invention.

FIG. 5 is a sectional view of an embodiment of the upper bearing and the hydrostatic bearing of the present invention.

FIG. 6 is a system head curve immediately after starting the submersible vertical pump.

FIG. 7 is a schematic sectional view of a conventional submerged pump facility for a liquefied gas tank.

[Explanation of symbols]

 1 Liquefied gas tank 2 Pumping pipe 3 Suction valve 4 Suspending wire 5 Submersible pump 6 Seat surface 7 Discharge pipe 8 Head plate 9 Motor rotor 10 Motor stator 11 Stage 12 Shaft 13 Impeller 14 Lower bearing 15 Middle bearing 15a, 15b Single row arrangement Deep groove type ball bearing 15c Ring spacer 15f Ball 15g Cage 16 Upper bearing 17 Axial thrust balancer 18 Casing 19A, 19B Hydrostatic bearing F Load

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroaki Yoda Inventor Hiroaki Yoda 603 Kuchidachi-cho, Tsuchiura-shi, Ibaraki Hiritsu Manufacturing Co., Ltd. Tsuchiura factory (72) Inventor Shigeru Sakai 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Hitachi, Ltd. (72) Inventor Genichiro Nakamura, 603, Jinritsucho, Tsuchiura, Ibaraki Prefecture, Tsuchiura Plant, Hiritsu Manufacturing Co., Ltd. (72) Inventor, Mitsuo Gazuma, Fukusaku, Omiya, Saitama 209-15 (72) Inventor, Koichi Moroto 15-10-402 Miyamatsu-cho, Hiratsuka-shi, Kanagawa

Claims (6)

[Claims] 1. A vertical axis submersible pump device for a liquefied gas tank, which is inserted into a pumping pipe hung in a liquefaction tank and sucks and discharges liquefied gas from the liquefaction tank, wherein the pump shaft and the pump shaft are rotationally driven. And a drive unit that is installed below the drive unit along the pump shaft,
An impeller that boosts the liquefied gas sucked from the liquefaction tank, a discharge hole that discharges the liquefied gas that is boosted by the impeller, a plurality of bearings that support the pump shaft, and a thrust load that is provided near the pump shaft. A shaft thrust balancer for liquefied gas tanks, which is composed of a shaft thrust balancer for reducing the load and a bearing provided near the shaft thrust balancer is a single row deep groove type ball bearing arranged in multiple rows. apparatus. 2. A vertical axis submersible pump device for a liquefied gas tank, which is inserted into a pumping pipe hung in a liquefaction tank and sucks and discharges liquefied gas from the liquefaction tank, wherein the pump shaft and the pump shaft are rotationally driven. Motor part, an impeller that is located below the motor part along the pump shaft, and that boosts the liquefied gas sucked from the liquefaction tank, a discharge hole that discharges the liquefied gas that is boosted by the impeller, and a bearing. Thrust balancer that reduces the thrust load on the shaft, the upper bearing that supports the pump shaft at a position higher than the motor position, and the shaft thrust balancer at a position lower than the motor position. And a lower bearing that supports the pump shaft at a position lower than the position where the impeller is arranged, and the above-mentioned middle bearing has a single-row depth. Each type ball bearing liquefied gas tank for standing-shaft submerged pump apparatus assumed arranged double row of. 3. A vertical shaft submerged pump device for a liquefied gas tank according to claim 1 or 2, wherein the double row ball bearing is a single row deep groove type ball bearing through a spacer along a pump axis direction. Vertical shaft submersible pump device for liquefied gas tanks with multiple rows of double-groove deep groove ball bearings. 4. A vertical axis submerged pump device for a liquefied gas tank, which is inserted into a pumping pipe hung in a liquefaction tank and sucks and discharges liquefied gas from the liquefaction tank, the pump shaft and the pump. A motor part that drives the shaft to rotate, an impeller that is located below the motor part along the pump shaft, and that boosts the liquefied gas sucked from the liquefaction tank, a shaft thrust balancer, and a booster that boosts the pressure. A discharge hole for discharging liquefied gas, an upper bearing above the position where the motor is placed, an upper bearing that supports the pump shaft, a position below the position where the motor is placed, and a position near the shaft thrust balancer. A middle bearing supporting the pump shaft and a lower bearing supporting the pump shaft at a position lower than the position where the impeller is arranged, and the middle bearing is a single unit along the pump shaft direction. Deep and each type ball bearings and a plurality of arrangement,
This is a double-row deep groove type ball bearing.The inner ring of this ball bearing is integrally fixed to the pump shaft, and a gap is provided between the outer ring outer circumference and the bearing housing. Between
A vertical shaft submersible pump device for a liquefied gas tank having a hydrostatic bearing for supporting the pump shaft during operation. 5. A vertical groove submerged pump device for a liquefied gas tank according to claim 4, wherein a plurality of single-row deep groove ball bearings are arranged along the pump axis direction to provide a double-row deep groove ball bearing. This ball bearing is a vertical shaft submerged pump device for a liquefied gas tank, which is arranged separately through a spacer. 6. The vertical submerged pump device for a liquefied gas tank according to claim 1, wherein the double row deep groove ball bearing is made of at least one of stainless steel and wear resistant steel. Vertical shaft submersible pump device for liquefied gas tanks.