JPS6033356Y2 - Low temperature submerged motor pump - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a low-temperature submerged motor pump for pumping low-temperature liquefied gas such as LPG or LNG.

In general, low-temperature liquefied gas has an extremely low temperature of -5°C to 200°C, and is close to its boiling point and is easily gasified by heat. Therefore, various considerations have been made in the low-temperature submerged motor pump that pumps this gas.

For example, in a low-temperature submerged motor pump in which a portion of the pressurized liquefied gas infiltrates into the bearing section and the inside of the housing 6 to lubricate the bearings, and into the inside of the motor to lubricate the bearings and cool the inside of the motor, the bearings are lubricated. The liquefied gas that cools the inside of the motor is maintained at an appropriate pressure to raise its boiling point, thereby preventing gasification due to the heat inside the bearing and the motor.

In other words, this conventional cryogenic submerged motor pump takes out a part of the pressurized liquefied gas from the discharge part of the final stage of the pump and supplies it to the bearing part and inside the motor, and also uses the orifice ease etc. to absorb the supplied liquefied gas. The liquefied gas inside the bearing and the motor is maintained at an appropriate pressure by being configured to be discharged to a pump suction section or the like through a constricted outlet.

By the way, during continuous operation of the low-temperature submerged motor pump configured in this way, appropriate pressure is applied to the liquefied gas inside the bearing and the motor, and the bearings are lubricated and the inside of the motor is cooled smoothly. If the motor stops at , the liquefied gas that was pressurizing the inside of the motor and the liquefied gas that was lubricating the bearings will become normal pressure.
The boiling point of the liquefied gas inside the motor and the bearing is lowered, and the heat of the motor and bearing itself causes the liquefied gas to gasify rapidly.

However, conventional low-temperature submerged motor pumps use part of the liquefied gas discharged from the final stage discharge part of the pump to lubricate the bearings and cool the inside of the motor. Unless the inside of the motor is cooled with liquefied gas, the liquefied gas will not flow to the bearing, and therefore the liquefied gas intake port is narrow.

Moreover, in order to maintain an appropriate pressure in the liquefied gas inside the bearing and the motor, the outlet is throttled with an orifice easel or the like.

Therefore, as mentioned above, even if gas is generated inside the motor and the bearing, the gas will only gradually escape from inside the motor.
If the motor is restarted immediately after stopping, the bearing and the inside of the motor will be operated in a gasified state, and there is a risk that the bearing and motor will burn out.

The present invention has been made in view of the above drawbacks, and an object of the present invention is to provide a low-temperature submerged motor pump that does not burn out the bearing and motor even when the motor is immediately restarted after stopping.

That is, the present invention provides a gas vent valve at the top of the motor that opens when the internal pressure of the motor becomes low, communicating the inside and outside of the motor, and closes when the pressure exceeds a first predetermined pressure. A flow rate control valve is provided to keep the hydraulic pressure inside the motor constant by communicating between the inside and outside of the motor and not allowing a predetermined flow rate to flow when the pressure exceeds a second predetermined pressure, which is a set pressure higher than the first predetermined pressure. The pump is configured to supply a portion of the liquefied gas intermediately discharged from the pump into the keyer from the lower part of the motor, and to supply a portion of the liquefied gas finally discharged from the pump to the bearing of the motor.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 is the upper bracket of the motor, 2 is the lower bracket of the motor, and the upper bracket 1 and the lower bracket 2 are integrated through an inner casing 3 and an outer casing 4 provided outside of the inner casing 3. It is fixed at

A stator 5 of the motor is fixedly mounted inside the inner casing 3, and a rotating shaft 7 with a rotor 6 of the motor fixed thereon is mounted on the upper bracket 1 and the lower bracket 2 with bearings 8a, It is rotatably supported by the shaft 8b.

That is, upper bracket 1, lower bracket 2, inner casing 3J stator 5, rotor 6, rotating shaft 7, bearing 8
A and 8b constitute a motor.

Further, at the bottom of the rotating shaft 7, a first impeller 9a and a second impeller 9 are provided.
b and an inducer 10 for guiding the liquefied gas to the first impeller 9a are fixedly attached and covered by a sub-casing 11 and a pump casing 12 fixedly attached to the lower bracket 2 of the motor.

In other words, it constitutes a two-stage compression pump section driven by the aforementioned motor.

13 is a casing fixedly attached to the upper bracket 1, and this casing 13 has a second discharge passage communicating with the first discharge passage 14 formed by the sub-casing 11, the pump casing 12, and the inner casing 3 and outer casing 4. A discharge passage 15 is formed.

16a and 16b are liquefied gas intake holes for bearing lubrication that communicate the first discharge passage 14 and the bearings 8a and 8b via filters 17a and 17b, respectively, and supply the final liquefied gas discharged from the pump to the bearings 8a and 8b; Reference numeral 18 indicates a liquefied gas intake hole for internal cooling of the motor, which communicates between the intermediate discharge passage 23 formed by the first impeller 9a and the pump casing 12, and the inside of the subcasing 11; This is a communication hole that communicates between the inside of 11 and the inside of the motor.

That is, 'the liquefied gas intake hole 18 for internal cooling of the motor and the communication hole 19 communicate the lower part of the motor with the intermediate discharge passage 23 of the pump to introduce the liquefied gas intermediately discharged from the pump into the motor, and the liquefied gas finally discharged from the pump. The configuration is such that the final discharge of the liquefied gas from the pump flows from the first discharge passage 14 to the bearings 8a and 8b by utilizing the pressure difference between the two.

Further, the liquefied gas intake hole 18 for internal cooling of the motor is provided at the lower part of the motor and is opened wide so that the liquefied gas can easily enter the motor from the lower part of the motor.

20 is a liquefied gas outlet hole provided in the casing 13;
Reference numeral 1 is a gas vent valve that is provided on the upper bracket 1, and opens when the pressure inside the motor becomes low to communicate the inside and outside of the motor, and closes when the pressure exceeds a first predetermined pressure; 22 is also provided on the upper bracket 1, and When the internal pressure exceeds a second predetermined pressure, which is a set pressure higher than the first predetermined pressure set by the gas vent valve 21, the inside and outside of the motor are communicated, and the pressure inside the motor is kept constant without allowing a predetermined flow rate to flow. It is a flow control valve that maintains the flow rate.

Next, the action will be explained.

The low-temperature submerged motor pump configured as described above is submerged in liquefied gas, and when the motor is driven to rotate the first and second impellers 9a and 9b and the inducer 10,
Due to the centrifugal action, pressure is gradually applied to the liquefied gas in the pump casing 12, and finally the pump
Liquefied gas is discharged into the second discharge passage 14.15.

At this time, the pressure inside the monitor is below the first predetermined pressure set by the gas vent valve 21, so the gas vent valve 21 is open, and the intermediate discharge passage 2 is opened by the centrifugal action of the first impeller 9a.
A part of the intermediate-pressure liquefied gas discharged into the motor 3 enters the inside of the motor through the liquefied gas intake hole 18 for internal cooling of the motor and the communication hole 19.

In this case, since the motor internal cooling liquefied gas intake hole 18 is formed to be large, the liquefied gas quickly enters the motor.

Furthermore, since the liquefied gas discharged into the first discharge passage 14 has a higher pressure than the intermediate discharge pressure due to the centrifugal action of the second impeller 9a, a portion of the liquefied gas is transferred to the filters 17a, 17b and the bearings due to the pressure difference. The gas enters the bearings 8a, 8b through the circulating liquefied gas intake holes 16a, 16b, and after lubricating the bearings 8a, 8b, enters the inside of the motor.

The pressure of the liquefied gas that has entered the bearings 8a*8b and the motor in this way is gradually increased, and the gas vent valve 21
When the first predetermined pressure is reached, the gas vent valve 2
1 closes, and when the second predetermined pressure set by the flow control valve 22 is reached, the flow control valve 22 opens, and the flow control valve 2
2 keeps the pressure constant, and the liquefied gas discharge hole 2
0 and is emitted to the outside of the motor.

Therefore, the liquefied gas that cools the inside of the motor and the bearing 8a
*The boiling point of the liquefied gas that lubricates 8b is thereby increased, cooling the inside of the motor and bearing 8a.

8b lubrication.

Next, if the motor is stopped for some reason, the second
Since the impellers 9a, 9b and inducer 10 stop rotating, liquefied gas is no longer discharged into the first discharge passage 14 and the intermediate discharge passage 18.

Therefore, the liquefied gas is no longer pumped into the bearings 8a, 8b and the inside of the motor, and the liquefied gas inside the motor and the bearings becomes normal pressure. It is rapidly gasified by the heat of ab itself.

However, since the upper bracket 1 is provided with a gas vent valve 21 that communicates between the inside and outside of the motor so that the pressure inside the motor is low, that is, below the first predetermined pressure, the gas generated inside the motor and the bearings 8a and 8b are removed. Gas is discharged from the gas valve 21 to the outside of the motor through the liquefied gas discharge hole 20.

Moreover, the liquefied gas intake hole 18 for internal cooling of the motor is formed large and is provided at the bottom of the motor, so that the liquefied gas is discharged from between the pump casing 12 and the inducer 10 → between the pump casing 12 and the first impeller 9a → to the intermediate discharge. Passage 23→
The liquefied gas intake hole 18 for internal cooling of the motor flows into the motor through the communication hole 19, and the gas generated inside the motor is pushed out toward the gas vent valve 21.

Therefore, even if gas is generated inside the motor and the bearing after the motor is stopped, the gas is quickly released from the inside of the motor, and even if the motor is restarted immediately, the bearings 8a, 8b and the inside of the motor will not be burnt out.

Next, when the motor is restarted, a portion of the liquefied gas discharged by the first impeller 9a passes through the motor internal cooling liquefied gas intake hole 18 and the communication hole 19 into the motor. In addition, a part of the liquefied gas discharged by the second impeller 9b is force-fed to the bearings 8a, 8b through the filters 17a, 17b and the liquefied gas intake holes 16a, 16b for bearing lubrication, so that The pressure of the liquefied gas increases, and when the pressure increases to a first predetermined pressure, the gas vent valve 21 closes.

When the gas vent valve 21 closes, the pressure of the liquefied gas inside the bearing and the motor further increases to a second predetermined pressure set by the flow rate control valve 22, and its boiling point increases.

Therefore, the bearings 8a and 8b are lubricated and the inside of the motor is cooled smoothly.

Incidentally, the liquefied gas intake hole 18 for internal cooling of the motor does not need to be provided in the sub-casing 11; it may be provided in the lower part of the motor, that is, in the lower part of the inner casing 3, and the intermediate discharge liquefied gas may be directly taken in.

In this case, there is no need to provide the communication hole 19 in the lower bracket 2.

Further, the gas vent valve 21 and the flow control valve 22 do not need to be provided on the upper bracket 1, and may be provided on the casing 13.

As described above, the present invention provides a dedicated gas vent valve on the top of the motor that communicates between the inside and outside of the motor when the pressure inside the motor becomes low, and closes when the pressure exceeds a first predetermined pressure. When the pressure reaches a second predetermined pressure, which is a set pressure higher than the first predetermined pressure, a flow control valve is provided which communicates the inside and outside of the motor and keeps the hydraulic pressure inside the motor constant while allowing a predetermined flow rate to flow. The multi-stage pump is configured to supply a portion of the pump's intermediate discharge liquefied gas into the motor from the bottom of the motor, and also to supply a portion of the pump's final discharge liquefied gas to the bearings. Even if gas is generated inside the motor and the bearing, the gas will escape from the motor immediately, and the bearing and the inside of the motor will not burn out even if the motor is restarted immediately.

Furthermore, since the cooling liquefied gas for the secondary track number and the motor is supplied directly from the intermediate discharge passage without passing through the bearing portion, there is an effect that the filter is less likely to be clogged with dirt or the like.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view showing an embodiment of the low-temperature submerged motor pump of the present invention. 1... Upper bracket, 2... Lower bracket, 3... Inner casing, 4...
・Outer casing, 5... Stator, 6...
...Rotor, 7...Rotating shaft, 8a, 8b...
...Bearing, 9a...First impeller, 9b...
...Second impeller, 1-0...Curve inducer, 11.
...Sub casing, 12...Pump casing, 13...Casing, 14...
...First discharge passage, 15...Second discharge passage, 1
6a, 16b...Liquified gas intake hole, 17a, 1
7b... Filter, 18... Liquefied gas intake hole, 19... Communication hole, 20... Liquefied gas outlet hole, 21...・Gas vent valve, 22...
...Flow control valve.

Claims (1)

[Scope of utility model registration request] In a low-temperature submerged motor pump that uses part of the liquefied gas discharged from a pump driven by a motor to lubricate the bearings of the motor and cool the inside of the motor, when the internal pressure of the motor becomes less than a first predetermined pressure, the inside and outside of the motor are communicated. and a gas vent valve that closes when the pressure exceeds a first predetermined pressure, and a gas vent valve that connects the inside and outside of the motor to flow a predetermined flow rate when the internal pressure of the motor exceeds a second predetermined pressure that is a set pressure that is higher than the first predetermined pressure. Therefore, a flow control valve that maintains a constant hydraulic pressure inside the motor is provided at the top of the motor, and the pump is configured as a multi-stage pump to supply a part of the intermediate discharge liquefied gas from the bottom of the motor into the motor. A low-temperature submerged motor pump, characterized in that the pump is configured to supply a portion of the liquefied gas finally discharged from the pump to a bearing of the motor.