JPH07208384A - Submerged pump device for liquefied gas tank - Google Patents

Abstract

PURPOSE:To restart a pump simultaneously with changeover to an emergency power source at electric power failure by providing a reverse rotation preventing mechanism constituted of a swing type claw on a rotary shaft side or fixed side, and a plate engaging with the swing type claw. CONSTITUTION:When rotary bodies are normally rotated and the prescribed discharge pressure is reached, the rotary bodies such as an engaging plate 2, an impeller 3, a rotary shaft 4, a balance disc 5, are floated, a point of contact with a swing type claw 1 is removed, and hence the swing type claw 1 and the engaging claw 2 are not worn. When a pump is stopped and the rotating speed of the rotary bodies such as the impeller 3, the rotary shaft 4, the balance disc 5 is reduced, the rotary bodies such as the engaging plate 2, the impeller 3, the rotary shaft 4, the balance disc 5, are brought down, and reverse rotation can be prevented by engaging the swing type claw 1 with the engaging plate 2.

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 liquefied gas tank suitable for preventing reverse rotation of a pump rotary shaft due to liquefied gas remaining in a pumping pipe when the pump is stopped. The present invention relates to a submersible pump device.

[0002]

2. Description of the Related Art A conventional submersible pump for a liquefied gas tank is
Unlike in Japanese Patent Laid-Open No. 1-301990, no reverse rotation prevention mechanism is provided, and since the rotating shaft is supported only by the bearings above and below the drive unit, it has a structure capable of rotating in both forward and reverse directions. .

[0003]

SUMMARY OF THE INVENTION In the above prior art,
During operation of the pump, liquefied gas is discharged from the suction port provided at the lower part of the pump through the impeller and the stage, and the discharge hole of the pump body. The liquefied gas discharged from the pump body passes through the pumping pipe and is discharged from the discharge pipe.

When the pump is stopped, a differential pressure is generated due to the difference between the liquid level of the liquefied gas remaining in the pump and the liquid level of the liquefied gas tank, and the liquefied gas in the pump flows back into the tank through the pump. Due to the action of the back flow of the liquefied gas in the pump, the pump rotating body rotates in the reverse direction.

If the motor is restarted in the reverse rotation state, an excessive force may be applied to the rotating shaft to damage it, and the motor may not be able to rotate, resulting in excessive current for a long time and burning of the motor. There is.

For this reason, the pump must be restarted for several tens of minutes before the reverse rotation is stopped.

Generally, a liquefied gas plant has a commercial power source and an emergency power source in case of a power failure. If commercial power fails, it will switch to emergency power within a few minutes. When the pump stops due to a power failure, gas cannot be supplied while the pump is stopped, and if this state continues for several tens of minutes, the social impact will increase, so it is necessary to restart the pump at the same time as the emergency power switch.

An object of the present invention is to provide a submerged pump device for a liquefied gas tank, which can restart the pump at the same time as switching the emergency power source even in the case of a power failure and can stably supply gas.

[0009]

In order to achieve the above object, there is provided a reverse rotation preventing mechanism comprising a swing type pawl on a rotary shaft or a fixed side and a plate meshing with the swing type pawl.

[0010]

Since the present invention is provided with the reverse rotation preventing mechanism, the pump rotating body such as the rotating shaft, the impeller and the motor is not subjected to an unreasonable force, and the life of the pump rotating body can be secured.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a submersible pump device with a reverse rotation preventing mechanism for a liquefied gas tank.

In FIG. 1, the plate 2 that meshes with the swing type pawl 1 is rotated by motors 7a and 7b in the same manner as the impeller 3, the rotating shaft 4 and the balance disc 5. The swing claw 1 is fixed to the pump cover by a bolt (not shown).

The swing-type pawl 1 meshes with the meshing plate 2 when the rotating body such as the impeller 3, the rotating shaft 4, the balance disk 5, etc. is not rotating. Impeller 3,
The rotating body such as the rotating shaft 4 and the balance disk 5 rotates forward,
When the discharge pressure reaches a certain level, the axial thrust balancer of the pump works as a normal function, and as shown in FIG. 2, the rotor such as the meshing plate 2, the impeller 3, the rotary shaft 4, the balance disc 5, and the like floats up. As described above, there is no contact with the swing claw 1, and the swing claw 1 and the meshing plate 2 are not worn.

When the pump stops, the impeller 3, the rotary shaft 4,
When the rotational speed of the rotating body such as the balance disk 5 decreases, the axial thrust balancer does not work as a normal function, and the mesh plate 2, the impeller 3, the rotating shaft 4, the balance disk 5, etc., the rotating body as shown in FIG. When is dropped, reverse rotation can be prevented by engaging the swing type claw 1 with the meshing plate 2 as shown in FIG.

According to this embodiment, there are the following effects.

Since there is no need to restart the pump with the rotating body rotating in the reverse direction, there is no possibility of damage to the rotating shaft.

Since the motor cannot be rotated, there is no possibility that the motor will burn out.

Next, a second embodiment will be described.

In FIG. 6, the plate 9 that meshes with the claw 8 having good flexibility is rotated by the motors 7a and 7b like the impeller 3, the rotating shaft 4 and the balance disc 5. The flexible claw 8 is fixed to the pump cover by a bolt (not shown).

The highly flexible claw 8 meshes with the meshing plate 9 when the rotating body such as the impeller 3, the rotating shaft 4, the balance disk 5, etc. is not rotating. When the rotating body such as the impeller 3, the rotary shaft 4, the balance disk 5 and the like rotates in the forward direction, the flexible claw 8 which is pushed and bent by the meshing plate 2 as shown in FIG. 7 rotates without meshing with the meshing plate 9.

When the pump is stopped, reverse rotation can be prevented by engaging the flexible claw 8 with the meshing plate 9 as shown in FIG.

The same effects as described above can be obtained by this embodiment as well.

Next, a third embodiment will be described.

In FIG. 9, the swing claw 10 is rotated by the motors 7a and 7b like the impeller 3, the rotating shaft 4 and the balance disc 5. The meshing plate 11 is fixed to the pump casing by bolts (not shown).

The swing-type pawl 10 meshes with the meshing plate 11 when the rotating body such as the impeller 3, the rotary shaft 4, the balance disk 5, etc. is not rotating.

When the rotating body such as the impeller 3, the rotating shaft 4, the balance disk 5 and the like rotates forward, the swing type claw 10 rotates without meshing with the meshing plate 11 as shown in FIG.

When the pump is stopped, reverse rotation can be prevented by engaging the swing type pawl 10 with the engaging plate 11 as shown in FIG.

The same effects as described above are also obtained by this embodiment.

In such a reverse rotation structure, it can be installed not only in the upper part of the pump but also in the middle part and the upper part of the pump.

[0030]

According to the present invention, it is possible to provide a submerged pump device for a liquefied gas tank capable of restarting the pump at the same time as switching the emergency power source even when a power failure occurs and stably supplying gas.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a submersible pump device showing Embodiments 1 and 3 of the present invention.

FIG. 2 is an enlarged view of a main part of the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a normal rotation state of the reverse rotation prevention mechanism of FIG.

FIG. 4 is an enlarged view of a main part of the first embodiment of the present invention.

5 is a cross-sectional view showing a reverse rotation prevention state of the reverse rotation prevention mechanism of FIG.

FIG. 6 is a sectional view of a submersible pump device showing a second embodiment of the present invention.

7 is a cross-sectional view showing a normal rotation state of the reverse rotation preventing mechanism of FIG.

8 is a sectional view showing a reverse rotation prevention state of the reverse rotation prevention mechanism of FIG.

FIG. 9 is a sectional view of a submersible pump device showing a third embodiment of the present invention.

10 is a view showing a normal rotation state of the reverse rotation prevention mechanism of FIG.
FIG.

11 is a diagram showing a reverse rotation prevention state of the reverse rotation prevention mechanism of FIG.
-X arrow sectional drawing.

[Explanation of symbols]

1, 10 ... Swing type claws, 2, 9, 11 ... Engaging plates,
3 ... Impeller, 4 ... Rotation axis, 5 ... Balance disc, 7
a, 7b ... Motor, 8 ... Claw with good flexibility.

Claims (1)

[Claims] 1. A submersible motor type submersible pump device, which is seated on a seating surface provided at the bottom of a lift pipe hung in a liquefied gas tank, wherein the pump rotor does not rotate in reverse when the pump is stopped. A submerged pump device for a liquefied gas tank, which is provided with a rotation prevention mechanism.