JPH06235393A - Submersible pump equipped with reverse revolution preventing mechanism - Google Patents

Abstract

PURPOSE:To prevent the restart of a pump in the reverse revolution state due to the couterflow of liquefied gas due to the stop of the pump by installing a reverse revolution preventing mechanism, as for the submersible pump consisting of a pump part consisting of an impeller and a casing for accommodating the rotary shaft of the impeller and a driving part which is directly connected with the rotary shaft and revolves the impeller. CONSTITUTION:An impeller 1 and a rotary shaft 2 and an outer race 4 and a cam 5 are revolved by a plurality of motors 7a and 7b, respectively. While, an inner race 6 is fixed on a head cover 8. Since, the moment acting around the contact point between the cam 5 with the outer race 4 increases, when the constitution parts 1-4 are not in revolution, the cam 5 contacts the inner race 6. Further, since the contact point with the inner race 6 does not exist when the constitution parts 1-4 and the cam 5 revolve in the normal direction and at least a prescribed number of revolution is obtained, the cam 5 is not worn out. Further, since the cam 5 meshes with the inner race 6 and the outer race 4 and the reverse revolution is prevented, when the constitution parts 1-4 reversely revolve, the rotary body is not applied with an unreasonable force, and even in an electric supply fault, a pump is restarted simultaneously with the switching of an emergent electric power source, and the stable production of gas is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submerged pump for a liquefied gas tank, and more particularly, it is suitable for preventing reverse rotation of a pump rotating shaft due to reverse flow of liquefied gas remaining in a pumping pipe when the pump is stopped. The present invention relates to a submersible pump for a liquefied gas tank.

[0002]

2. Description of the Related Art A conventional submersible pump for liquefied gas is disclosed in
As in Japanese Patent Laid-Open No. 1-301990, no reverse rotation preventing mechanism is provided and the rotating shaft is supported only by the bearings above and below the drive unit, so that the structure can rotate in both forward and reverse directions.

[0003]

As described above,
In the above conventional technique, during pump operation, liquefied gas is sucked up by the impeller from the suction port provided at the lower part of the pump, passes through the impeller and the stage, and is discharged from the pump body discharge hole. 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 in the liquid level of the liquefied gas remaining in the pump, 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. When restarting in the state of reverse rotation, excessive force may be applied to the rotating shaft, causing damage, and the motor cannot rotate, resulting in excessive current flowing for a long time.
The motor may burn out. Due to the above problems, the restart of the pump must wait for tens of minutes before the reverse rotation stops.

Generally, a liquefied gas plant has a commercial power source and an emergency power source during a power failure. If the commercial power supply stops, it will switch to the emergency power supply within a few minutes. When the pump stops due to a power failure, gas cannot be produced while the pump is stopped, and if this state continues for several tens of minutes until the pump can be restarted, the social impact will increase. Need to reboot.

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

[0007]

In order to achieve the above object, the present invention provides an outer race that rotates together with a rotary shaft, an inner race fixed to a pump body, and a gap between the outer race and the inner race. It is a reverse rotation prevention mechanism that consists of a cam that is sandwiched and rotates with the outer race.

Further, a reverse rotation preventing mechanism composed of a pressure receiving plate for receiving the dynamic pressure of the pump discharge liquid and a rotating disk attached to the rotating shaft is provided.

Further, a reverse rotation preventing mechanism including a rotary plate having a friction surface attached to the rotary shaft and a rotary plate having a friction surface on one side is provided.

[0010]

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

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a vertical sectional view of a submersible pump with a reverse rotation preventing mechanism for a liquefied gas tank. In the figure, the outer race 4 and the cam 5 are rotated by the motors 7a and 7b, similarly to the impeller 1, the rotating shaft 2 and the balance disc 3. The inner race 6 is fixed to the head cover 8 by bolts (not shown).

When the impeller 1, the rotary shaft 2, the balance disc 3, and the outer race 4 are not rotating, the cam 5 has a large moment acting around the contact point between the outer race 4 and the cam 5. , Is in contact with the inner race 4. When the impeller 1, the rotating shaft 2, the balance disc 3, the outer race 4 and the cam 5 rotate forward and reach a certain number of revolutions or more, the cam 5 loses its contact with the inner race 4 as shown in FIG. Does not wear.

When the impeller 1, the rotary shaft 2, the balance disk 3, and the outer race 4 rotate in the opposite directions, the moment acting on the cam 5 around the contact point between the outer race 4 and the cam 5 becomes small, and the cam 5 contacts the inner race 4. Have a
The cam 5 engages with the outer race 4 and the inner race 6 to prevent reverse rotation.

According to this embodiment, since the pump is not restarted while the rotating body is in the reverse rotation state, there is no possibility of damaging the rotary shaft, and the motor cannot be rotated, so the motor is burned. You can eliminate the possibility.

Next, a second embodiment will be described.

During pump operation, the flow of pump discharge liquid is as shown in FIG. At this time, the pressure receiving plate 10 is lifted above the pump by the dynamic pressure of the pump discharge liquid, and the pressure receiving plate 10 does not contact the rotating disc 11 provided on the rotating shaft 2 as shown in FIG. In other words, the pressure receiving plate 10 and the rotating disc 11 do not wear when the pump is operating in the normal rotation.

When the pump is stopped and the liquefied gas flows backward through the discharge port 12 as shown in FIG. 5, the pressure receiving plate 10 is pressed against the rotating disk 11 by the dynamic pressure of the liquefied gas, and the pressure receiving plate 10 is pressed.
With the friction of the rotating disk 11, the reverse rotation of the pump can be prevented.

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

Next, the third embodiment will be described. Regarding the structure of the pump shown in FIGS. 6 and 7, when the pump is stopped, the rotary shaft 2 is in a state of being lowered below the pump as shown in FIG. . When the pump is operating, the rotary shaft 2 is in a floating state as shown in FIG. As a result, the rotary plate 16 attached to the rotary shaft 2 does not contact the fixed plate 15 during pump operation as shown in FIG. When the pump stops and the rotary shaft 2 floats down from the pump, the rotary plate 16 and the fixed plate 15 come into contact with each other as shown in FIG. As a result, the reverse rotation of the pump can be prevented by the friction between the rotary plate 16 and the fixed plate 15, and the same effect as above can be obtained in this embodiment.

[0020]

According to the present invention, it is possible to provide a submerged pump for a liquefied gas tank capable of stable gas production by restarting the pump at the same time as switching the emergency power supply even when a power failure occurs.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a pump according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the essential parts of the first embodiment.

FIG. 3 is an enlarged cross-sectional view of the essential parts of the first embodiment.

FIG. 4 is an enlarged vertical cross-sectional view of the essential parts of Embodiment 2 of the present invention.

FIG. 5 is an enlarged vertical cross-sectional view of the essential parts of Embodiment 2 of the present invention.

FIG. 6 is an enlarged vertical cross-sectional view of the essential parts of Embodiment 3 of the present invention.

FIG. 7 is an enlarged vertical cross-sectional view of the essential parts of Embodiment 3 of the present invention.

[Explanation of symbols]

1 ... Impeller, 2 ... Rotation axis, 3 ... Balance disc, 4
… Outer race, 5… Cam, 6… Inner race, 7
a, 7b ... Motor, 8 ... Head cover, 10 ... Pressure receiving plate,
11 ... Rotating disk, 12 ... Discharge port, 15 ... Fixed plate, 16 ...
Rotating plate.

Claims (1)

[Claims] 1. A pump unit including an impeller, a rotary shaft for rotating the impeller, a casing accommodating the impeller, a driving unit for rotating the impeller, which is directly connected to the rotary shaft at an upper portion of the pump unit. A submersible pump with a reverse rotation preventing mechanism, comprising a reverse rotation preventing mechanism.