JP3225190B2 - Submersible pump device for liquefied gas tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submersible pump for a liquefied gas tank, and more particularly to a submersible pump for a liquefied gas tank for storing a liquefied gas such as liquefied natural gas. While preventing backflow of the liquid, keeping the inside of the liquid pumping tube in a full state, and having a structure suitable for reducing the bearing load when starting and stopping the pump,
The present invention relates to a submerged pump device for a liquefied gas tank suitable for reducing the weight of a closing plate on the upper part of a liquid lifting pipe.

[0002]

2. Description of the Related Art A general immersion pump device for a liquefied gas tank will be described with reference to FIGS.

FIG. 6 is a system diagram of a general immersion pump device for a liquefied gas tank, and FIG. 7 is a sectional view of a conventional immersion pump device for a liquefied gas tank.

In FIGS. 6 and 7, 1 is a liquefied gas tank,
2 is a pumping pipe suspended in the liquefied gas tank 1, 2a
Is a head plate relating to a closing plate having a pump lifting mechanism at the top of the pumping pipe 2, 3 is a suction valve provided at the lower part of the pumping pipe, 4 is a suspending wire, and 5 is a pump inside the pumping pipe 2. Is a submerged pump installed on the seat surface 21 on the suction valve 3.

[0005] Reference numeral 10 denotes a discharge pipe provided above the pumping pipe 2;
11 is a check valve provided before the plurality of discharge pipes 10 are connected to the mother pipe 14, 12 is a discharge hole provided in an intermediate portion of the immersion pump 5, 13 is a minimum flow branched from the discharge pipe 10. Piping, 16 is a lift bar for lifting the pump, 17
Denotes a motor cable, 18 denotes a vibration meter cable, and 30 denotes a hoist for lifting.

That is, in the immersion pump device shown in FIG. 7, the immersion pump 5 includes a top plate 1 a in the liquefied gas tank 1.
Is suspended vertically from the head plate 2a by a suspending wire 4, for example, several tens of meters in length, and is seated on a seating surface 21 at the lower part of the liquid pumping tube 2. I have. The liquefied gas sucked from the suction valve 3 is pressurized by the pump section, flows out through the discharge hole 12 provided in the center of the pump into the liquid pumping pipe 2, flows upward, and is discharged from the discharge pipe 10 above the liquid pumping pipe 2. You.

FIG. 6 is a system diagram of a liquefied gas tank submersible pump device which is generally used in the past. A plurality of liquid pumping tubes 2 are suspended in one liquefied gas tank 1 and each liquid pump 2 is suspended. The discharge pipe 10 on the upper part of the pipe 2 is configured to be assembled to a mother pipe 12 via a check valve 11.

In such a conventional apparatus, the submersible pump 5
Stops the operation, the liquefied gas remaining in the pumping pipe 2 circulates through the pump through the discharge hole 12 in the center of the pump, and then flows back from the suction valve 3 to the liquefied gas tank 1 to return to the pumping pipe 2.
Is gradually lowered and stabilized at the same level as the liquid level in the liquefied gas tank 1. Therefore, when the submerged pump 5 is restarted, the submerged pump 5 needs only a small discharge pressure to pump up the liquid until the submerged pump 5 fills the liquid pumping tube 2 with the discharged liquefied gas. A predetermined discharge pressure cannot be generated.

Generally, a submerged pump for a liquefied gas tank is
For example, as described in Japanese Patent Publication No. Sho 61-5558, an axial thrust balancing device is provided to reduce the thrust force applied to the bearing to zero during the operation of the pump. However, since this axial thrust equilibrium device functions in a state in which the pump generates a predetermined discharge pressure, the bearing (not shown in FIG. 7) of the submerged pump 5 is configured so that the pressurized liquefied gas is supplied to the pumping pipe. The bearing is loaded with the weight of the pump rotor as a thrust load for about 3 minutes before filling in 2.

To prevent backflow of the liquefied gas in the pumping pipe 2;
As a immersion pump device for a liquefied gas tank, for example, a technique described in Japanese Patent Application Laid-Open No. 1-177493 is known.
In this publication, a check valve is provided at the discharge hole of the submerged pump in order to prevent the liquefied gas from flowing back in the liquid pumping pipe when the pump is stopped. However, since this check valve cannot be completely closed, a slight backflow occurs. Further, when the liquefied gas is a gas type that is easily vaporized, it is vaporized by heat input from the surroundings. The liquid level of the liquid being pumped tube gradually decreases, and leave it for a long time the pump is stopped, the liquid surface height of the liquid being pumped tract, becomes the same as the liquid level of the end liquefied gas tank problem for, it has not been enough consideration.

Further, for example, the drawings of Japanese Patent Application Laid-Open Nos. 1-177493 and 1-301990 disclose the structure of a closed portion at the top of the liquid pumping tube 2. As shown in FIG. 7, the structure of the closing portion described in these publications guides a lift bar 16 that lifts and lifts the pump on a flat disk, and also includes a guide support portion that supports the weight of the pump, a motor cable 17 and a vibration meter cable 18. The opening at the top of the liquid-pumping tube 2 is closed by a head plate 2a having a pipe that draws out the wiring laid in the liquid-pumping pipe 2 to the outside.

[0012]

In the above prior art,
When the submersible pump is started, a thrust load acts on the bearing, and the submerged pump for a liquefied gas tank, in which the life of the bearing is greatly influenced by the presence or absence of the thrust load, has a problem that the life of the bearing is significantly shortened. Further, since the head plate at the top of the pumping tube receives the discharge pressure of the pump at the flat disk portion, there is a problem that the plate thickness is increased and the weight is increased.

An object of the present invention is to provide a liquefied gas tank with a plurality of tanks .
In case any of the platform installed in the submerged pump is stopped
Also, when the stopped pump is restarted ,
Reduce thrust loads, it is to obtain a submersible pump apparatus for a liquid <br/> of gas tank which can Succoth if the bearing life extension.

[0014]

To achieve the above object, according to the solution to ## calling according to the liquefied gas tank for submersible pumping system of the present invention
Ming arrangement includes a plurality of lifting liquid pipe which is suspended in a liquefied gas tank, a suction valve provided at the bottom of the lift liquid pipe, wherein the liquefied gas tank top is lowered into the liquid being pumped pipe on the suction valve and a plurality of submersible pumps installed in the seating surface of the,
Comprising a discharge hole above the vicinity of the intermediate portion of the submersible pump and out the discharge of the pressurized liquefied gas in the pump in liquid being pumped tube, a check valve in the discharge hole is provided, wherein the top of each liquid being pumped tube A discharge pipe for sending liquefied gas to the outside is connected, and at the top of each pumping pipe
In submersible pump device for configuration liquefied gas tank to connect to the main pipe via a check valve is provided with a closure plate having a pump lifting mechanism, each said discharge pipe of each lifting liquid pipe, before
Note that each submerged pump has a pump
When a constant discharge pressure is generated, the thrust bearing
Axial thrust that functions to make the thrust force almost zero
A strut mechanism is provided, and the discharge pipes arranged above the plurality of liquid supply pipes are connected to each other by a communication pipe on the upstream side of a check valve leading to the mother pipe.

[0015] Incidentally, or provide a diaphragm mechanism in the communicating pipe, or a control valve provided in the communicating pipe, before pump operation may constitute a control circuit to open the control valve.

Further , the present invention relates to a submerged pump for liquefied gas of the present invention.
Another aspect of the invention is that a pump is lifted at the top of the pumping pipe.
Includes a closure plate having a lower mechanism, the closure plate includes a flange for fluxing the liquid being pumped tube, a pressure receiving plate having a curved portion for receiving the pressure of the liquid being pumped tube, guide the lift bar mounted through the receiving plate It comprises a support portion and a support plate that receives a pump load applied to a guide support portion provided inside the pressure receiving plate.

The operation of the above technical means is as follows.

By preventing the liquid level in the pumping pipe from lowering and keeping the liquid filled state at all times, the submerged pump can generate a predetermined pump discharge pressure at the same time as the startup. For this reason,
The thrust force acting on the bearing when the submersible pump is activated can be reduced to zero by the function of the axial thrust balancing device. This operation has the advantage that the bearing life can be extended.

Further, by forming the pressure receiving portion of the head plate into a plate material having a hemispherical curved surface, the thickness of the pressure receiving portion can be significantly reduced, and a support plate for supporting the guide supporting portion to which the pump weight is added when the pump is lifted. Is provided separately, the weight of the head plate can be greatly reduced. For this reason, it is possible to reduce the size of the hoist for pump lifting, which is installed on the liquefied gas tank top plate, and to improve the efficiency and safety of lifting work.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a longitudinal sectional view of a immersion pump device for a liquefied gas tank according to one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a immersion pump of the device of FIG. 1, and FIG. 1 is a system diagram of a submerged pump device for a liquefied gas tank according to one embodiment. In the figure, the same reference numerals as those in FIGS. 6 and 7 denote the same parts, and a description thereof will be omitted.

As shown in FIG. 1, the immersion pump 5 is installed so as to be seated on a seat surface 21 provided at the bottom of the liquid pumping pipe 2 suspended in the liquefied gas tank 1.

As shown in FIG. 2, the structure of the submersible pump 5 is as follows: a rotating body portion including an impeller 5E, a motor rotor 5G, and a shaft 5J, an upper bearing 5K, a middle bearing 5L, and a lower bearing for supporting the rotating body portion. 5M, stage 5F, motor stator 5
H, a fixed portion composed of a casing 5N, and a shaft thrust balance mechanism 5P. A plurality of discharge holes 12 are opened at an intermediate portion between the pump unit including the impeller 5E and the like and the motor unit.
Is equipped.

A suction valve 3 is provided at the bottom of the pumping pipe 2.

The opening at the top of the pumping pipe 2 is closed by a head plate 2A composed of a pressure receiving plate and a support plate.
A discharge pipe 10 is connected to an upper part of the liquid pumping pipe 2.

FIG. 3 shows the discharge pipe 10 and beyond. That is, each discharge pipe 10 of the plurality of liquid pumping pipes 2 is connected to the mother pipe 14 via the check valve 11, and liquefied gas discharged from each liquid pumping pipe 2 is joined. The check valve 11 prevents the high-pressure discharge liquid discharged from each of the liquid supply pipes 2 from flowing back and flowing back.

In front of the check valve 11 (upstream side) of the discharge pipe 10, a minimum flow pipe 13 for preventing the shut-off operation of the pump is provided for each discharge pipe 10. It leads to the liquefied gas tank 1. Further, each discharge pipe 10 is connected by a communication pipe 18.

The operation of such a device during pump operation will be described.

The flow of the liquefied gas during the operation of the pump is as follows:
The liquefied gas in the liquefied gas tank 1 is sucked into the immersion pump 5 from the suction valve 3, pressurized by the rotation of the impeller 5 </ b> E, and discharged from the discharge hole 12 provided in the center of the pump to the liquid pumping pipe 2. The check valve 22 installed in the discharge hole 12 is opened by the discharge pressure. The liquefied gas discharged from the pump passes through the pumping pipe 2 and is sent from the discharge pipe 10 to the outside of the liquefied gas tank.

After the discharge pipe 10, the gas passes through a check valve 11,
The liquid is led to the mother pipe 12 and sent to an evaporator (not shown) that merges with the liquefied gas discharged from another discharge pipe.

When the immersion pump 5 stops, the liquefied gas remaining in the liquid pumping pipe 2 remains in the liquid pumping pipe 2 due to the check valve 22 of the discharge hole 12 and the closing of the seating surface 21. . The liquid level of the liquefied gas remaining in the liquid pumping pipe 2 gradually increases due to leakage due to the non-perfect closing of the check valve 22 and the seat surface 21 of the pump discharge hole 12 and vaporization of the liquefied gas due to external heat input. However, since the liquefied gas of another operating pump is supplied from the communication pipe 18, the inside of the liquid pumping pipe 2 is maintained in a full state.

When the submersible pump 5 is restarted, since the inside of the liquid pumping tube 2 is full as described above, the submerged pump 5
Can generate a predetermined discharge pressure simultaneously with activation.

That is, the shaft thrust balance mechanism 5P functions at the same time as the pump is started, the bearing thrust load is reduced to zero, and the bearing life can be extended.

According to this embodiment, it is possible to eliminate the disadvantage of the submerged pump for a liquefied gas tank, that is, the adverse effect on the bearing life due to the bearing load at the time of starting the pump, and to improve the reliability.

FIG. 4 is a system diagram of a submerged pump device for a liquefied gas tank according to another embodiment of the present invention. In the figure, FIG.
Since the parts denoted by the same reference numerals are the same as those in the previous embodiment, the description thereof will be omitted.

The embodiment of FIG. 4 differs from the embodiment of FIG. 3 in that an orifice 19 relating to a throttle mechanism is provided in a communication pipe 18A.
That is, This makes it possible to adjust the amount of liquid supply to an appropriate level.

FIG. 5 is a system diagram of a submerged pump device for a liquefied gas tank according to still another embodiment of the present invention. In the figure, components having the same reference numerals as those in FIG. 3 are the same as those in the previous embodiment, and the description thereof is omitted.

The embodiment of FIG. 5 differs from the embodiment of FIG. 3 in that a valve (control valve) 20 is provided in the communication pipe 18B.

When the submersible pump 5 is stopped for a long period of time, liquefied gas is supplied to the liquid pumping pipe 2 during which the pump is stopped, although the operation efficiency is slightly reduced, as shown in FIG. In addition, a valve 20 is provided in the communication pipe 18B, and the valve 20 is closed and the liquid supply is stopped during a period when the operation is not planned. Before the operation, the valve is opened and the liquefied gas is supplied to the liquid pumping pipe 2 so that the liquid is filled. Then, an efficient method of starting the submerged pump 5 can be taken.

Next, the suspension mechanism will be described with reference to FIG.

The head plate 2A at the top of the pumping pipe 2 shown in FIG. 1 has a flange 2e joined to the pumping pipe 2 and a hemispherical curved surface portion which receives the pressure in the pumping pipe 2 and receives a pressure. Plate 2d, a guide support for a lift bar 2b penetrating through the pressure receiving plate 2d, and a support plate 2c for receiving a pump load applied to the lift bar 2b provided inside the pressure receiving plate 2d.
It consists of:

The pressure receiving portion is formed via the curved surface portion of the pressure receiving plate 2d, and the weight of the pump during lifting is supported by the support plate 2C in the pressure receiving plate 2d. The weight can be greatly reduced as compared with the head plate of FIG. For this reason, the hoist 30 for lifting above the liquefied gas tank can be downsized, and the efficiency of lifting operation and the safety can be improved.

Although the above suspension mechanism has been described as an example in which the head plate is reduced in addition to the configuration of the previous embodiment , this head plate reduction measure is a lifting method that does not have the configuration of the previous embodiment. It can be applied to liquid tubes.

[0044]

According to the present invention, multiple liquefaction gas tank
When one of several installed submersible pump devices stops
Even in the case, since the inside of the pumping tube can be kept full ,
There is an effect that a thrust load acting on the bearing when the stopped pump is restarted is reduced, and a submerged pump device for a liquefied gas tank that can prolong the life of the bearing is obtained .

Further, the achieved weight reduction of the head plate, Ru enhances the miniaturization of the hoist, the working efficiency, safety
It becomes possible .

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view of a submerged pump of the apparatus of FIG. 1;

FIG. 3 is a system diagram of a submerged pump device for a liquefied gas tank according to an embodiment of the present invention.

FIG. 4 is a system diagram of a submerged pump device for a liquefied gas tank according to another embodiment of the present invention.

FIG. 5 is a system diagram of a submerged pump device for a liquefied gas tank according to still another embodiment of the present invention.

FIG. 6 is a system diagram of a general immersion pump device for a liquefied gas tank.

FIG. 7 is a sectional view of a conventional immersion pump device for a liquefied gas tank.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquefied gas tank, 2 ... Pumping pipe, 2A ... Head plate, 2b ... Lift bar, 2c ... Support plate, 2d ... Pressure receiving plate,
2e: flange, 3: suction valve, 5: submerged pump, 10 ...
Discharge pipe, 11: check valve, 12: discharge hole, 14: mother pipe, 1
8, 18A, 18B: communication pipe, 19: orifice, 20
... Valve, 21 ... Seat surface, 22 ... Check valve.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-7-189982 (JP, A) JP-A-1-301990 (JP, A) JP-A-6-307376 (JP, A) JP-A-59-1984 122796 (JP, A) JP-A-1-177493 (JP, A) JP-A 63-100688 (JP, U) JP-A 63-7296 (JP, U) JP-A 61-39492 (JP, U) JP-B61-5558 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04D 7/02 F04D 13/00 F17C 7/00 F04B 15/06

Claims (5)

(57) [Claims] 1. A plurality of lifting liquid pipe which is suspended in a liquefied gas tank, a suction valve provided at the bottom of the lift liquid pipe, wherein the liquefied gas tank top is lowered into the liquid being pumped pipe on the suction valve and a plurality of submersible pumps installed in the seating surface of the,
Comprising a discharge hole above the vicinity of the intermediate portion of the submersible pump and out the discharge of the pressurized liquefied gas in the pump in liquid being pumped tube, a check valve in the discharge hole is provided, wherein the top of each liquid being pumped tube A discharge pipe for sending liquefied gas to the outside is connected, and at the top of each pumping pipe
In submersible pump device for configuration liquefied gas tank to connect to the main pipe via a check valve is provided with a closure plate having a pump lifting mechanism, each said discharge pipe of each liquid being pumped tube, each submersible pump The pump is operated by
Apply load to the thrust bearing with the specified discharge pressure
Axial thrust function to make the thrust force almost zero
A submersible for a liquefied gas tank , comprising: a last balance mechanism, wherein the discharge pipes disposed above the plurality of liquid pumping pipes are connected to each other by a communication pipe at an upstream side of a check valve leading to a mother pipe. Submersible pump device. 2. The immersion pump device for a liquefied gas tank according to claim 1, wherein a throttle mechanism is provided in the communication pipe. 3. The submerged pump device for a liquefied gas tank according to claim 1, wherein a control valve is provided in the communication pipe, and a control circuit is configured to open the control valve before the pump is operated. 4. A closing plate having a pump lifting mechanism, a flange joined to a liquid pump pipe, a pressure receiving plate having a curved surface portion receiving pressure in the liquid pump pipe, and a guide support for a lift bar penetrating and attached to the pressure receiving plate. 2. The submerged pump device for a liquefied gas tank according to claim 1, wherein the submersible pump device comprises a support plate for receiving a pump load applied to a guide support portion provided inside the pressure receiving plate. 5. A closing plate having a pump lifting mechanism at the top of the liquid pumping tube, the closing plate being a flange joined to the liquid pumping tube, and a pressure receiving plate having a curved surface portion receiving pressure in the liquid pumping tube. 5. A guide plate according to claim 1 , further comprising a guide support portion of the lift bar penetrating through the pressure receiving plate, and a support plate receiving a pump load applied to the guide support portion provided inside the pressure receiving plate. Kano liquefied gas tank for a submersible pump device.