JPS6011696A - Down hole pump - Google Patents

Abstract

PURPOSE:To permit the smooth pumping action by combining a canned motor and a multistage pump and operating the pump, feeding purge liquid into the gap between the bearings, stator, and the rotor of the canned motor through a feeding pipe exclusively used. CONSTITUTION:The pump for pumping-up subterranean hot water, etc. is constituted of a pump part 10 and a canned motor part 12. Said pump part 10 has multistage pump chambers 14a and 14b, and the fluid absorbed from the suction port 16 at the lower-edge center part is discharged from a discharge port 18 formed onto the outer periphery of the pump chamber 14b in the rear stage. While, the canned motor part 12 has the structure in which a stator 20 and a rotor 22 are closed by each cann, and an annular discharge passage 38 surrounded with a pump casing 36 is installed onto the outer periphery of a stator shell 21. A purge-liquid feeding pipe 44 is connected to the upper-edge opened part of a communication hole 42 drilled at the center of a rotor shaft 28, and the purge liquid can be supplied to bearings 30, 30, and 34 from each discharge hole 46.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a pump using a canned motor for pumping underground water, etc., and in particular to a downhole pump that can smoothly pump hot water. Regarding the improvement of

[Prior art and its problems]

Generally, shaft-driven pumps, electric submersible motor pumps, and turbine-driven submersible pumps are known as pumps for pumping up groundwater and the like. However, in shaft-driven pumps, the motor is installed on the ground, and the drive shaft of this motor and the impeller of the pump section are connected by a long shaft, and in order to sufficiently improve pump performance, the strength of the shaft is required. It is necessary to give sufficient consideration to the bearing means and bearing means. That is, in this case, since it is necessary to provide a large number of bearings for the long shaft, it is difficult to manage the lubrication conditions of each bearing, and bearing failures are likely to occur frequently.
There are limits to the descending distance of the pump and the temperature of the liquid handled by the pump.

In addition, electric submersible motor pumps are an integrated system in which a motor with a sealed structure and a pump part are connected in the axial direction, and although it has the advantage of not requiring a long shaft, it does not require the use of a sealed liquid. However, they require a strict sealing structure and have limited heat resistance. Moreover, when performing high-temperature liquid service or configuring a high-output machine, a large heat transfer area is required to cool the motor, so it is necessary to install an oil cooler and arrange the motor in series. However, the problem is that reliability declines due to equipment becoming more sophisticated and complex. Furthermore, turbine-driven pumps cannot achieve the theoretical performance and have problems with the sealing system of the turbine section, making them difficult to use in practice.

Note that electric submersible motor pumps and turbine-driven submersible pumps generally use the well above the pump as a discharge path, so the outer circumference of the pump and the well must be connected to prevent the discharge fluid from returning to the pump suction side. It is necessary to seal the gap with the inner diameter of the well at least at one location. Therefore, when implementing this type of sealing method, it is possible to perform the sealing function reliably from above ground to hundreds of meters underground, and during maintenance, the sealing function can be reliably performed from above ground. It is extremely difficult to construct a structure that can be solved and that can sufficiently withstand the reaction force of the pump, and there has been no satisfactory solution.

[Purpose of the invention]

The purpose of the present invention is to integrate the pump part and the motor part, make the motor small and have a small diameter structure, maintain sufficient pump performance, have excellent heat resistance, and significantly extend the pumping distance. Furthermore, it is an object of the present invention to provide a downhole pump that does not require sealing means for forming a passage for pump liquid when installing the pump, and is easy to handle and maintain.

[Key points of the invention]

The present invention combines a pump section consisting of a single-stage or multi-stage pump chamber and a canned motor section, and integrally provides a pump fluid discharge passageway communicating with a discharge port of the pump section on the outer periphery of the canned motor section. A through hole is bored in the center of the rotor shaft of the part, the through holes are opened to communicate with each other, a purge liquid supply pipe is connected to the one bearing, and a purge liquid discharge port is connected to the other bearing side. It is characterized by providing.

That is, in the present invention, the canned motor and the pump section consisting of multi-stage pump chambers are coaxially connected to increase the heat-resistant insulation strength of the canned motor, and the pump fluid discharge passage is integrally provided on the outer periphery of the L7 canned motor section. The pump is connected to the discharge pipe at the end opposite to the suction side of the pump, and supplies stable purge liquid to the canned motor from the outside to lubricate the bearings and cool the motor. It is possible to realize a downhole pump whose overall dimensions can be made as small as possible, which eliminates the need for sealing means between the pump outer circumference and the borehole inner diameter, and which is easy to install and maintain.

As an example of the pump liquid discharge passage in the present invention, a multi-stage pump chamber is coaxially connected to the lower end of the canned motor part, and an annular discharge passage surrounded by a pump casing is provided on the outer surface of the stator of the canned motor part. It is suitable if

Alternatively, a multi-stage pump chamber may be coaxially connected to the lower end of the canned motor section, and a plurality of discharge pipes may be provided inside the stator of the canned motor section.

Furthermore, in the downhole pump described above.

By configuring the canned motor section to perform variable speed control when starting and stopping, smooth pump operation can be achieved.

[Embodiments of the invention]

Next, embodiments of the downhole pump according to the present invention will be described in detail below with reference to the accompanying drawings.

FIGS. 1 and 2 are sectional views of essential parts of an embodiment of a downhole pump according to the present invention. That is, the pump of this embodiment has a pump section 10 and a canned motor section 12.
The pump section 10 is composed of a canned motor section 12.
It is placed below the . The pump section 10 is configured as multi-stage pump chambers 14a and 14b, with the pump chamber 14 in the previous stage
! A pump suction port 16 is provided at the center of the lower end of I, and a pump discharge port 18 is provided at the outer periphery of the pump chamber 14b at the rear stage.The canned motor section 12 has been subjected to super heat-resistant processing, and the stator 20 and rotor 22 are each canned. The canned motor section 12 has a well-known sealed canned structure, and bearing housings 24.2b are installed at both ends of the canned motor section 12.
The rotor shaft 28 is held by a bearing provided through the rotor shaft 28. However, a journal bearing 60 and a thrust bearing 32 are provided at the boundary between the canned motor section 12 and the pump section 10, and a journal bearing 34 is provided at the other end.

Further, in the pump of this embodiment, an annular discharge passage 68 surrounded by a pump casing 66 is provided on the outer periphery of the stator shell 21 of the canned motor section 12.
The annular discharge passages 38 are assembled into a single tubular discharge opening 40 at the upper end thereof. In this case, a through hole 42 is bored in the center of the rotor shaft 28 and the through hole 42 is connected to the rotor shaft 28.
8 is opened at the upper end side, and a purge liquid supply pipe 44 is passed through the opening from the outside for communication connection. In addition,
Providing radially projecting ribs 23 on the outer circumferential surface of the stator shell 21 forming the annular discharge passage 38 has the advantage of facilitating attachment of the outer casing during assembly and providing a rectifying effect to the pump discharge liquid. can get. However, the rotor shelf 28 has a purge liquid discharge hole that communicates with the through hole 42 in the radial direction of the rotor shaft 28 so that the purge liquid can be supplied to the W moving surfaces of the bearings 30, 32, and 34 that support both ends of the rotor shelf 28. A hole 46 is drilled.

In the canned motor pump configured in this manner, a conductive cable 50 for connecting the discharge pipe 48 to the tubular discharge port 40 and supplying driving power to the canned motor section 12 is appropriately connected and arranged at the upper end thereof. , it can be inserted into the inside of a steel pipe 52 that has been drilled as an underground well having a required inner diameter dimension, and can be made to function as a submerged type canned motor pump.

A discharge port 54 for discharging the purge liquid supplied into the canned motor section 12 to the pump liquid discharge port 4091 is appropriately provided at the upper end of the canned motor section 12.

Next, the operation of the downhole pump having the above structure will be explained.

First, the canned motor pump is inserted into a steel pipe 52 driven into an underground well, and the pump part 1° and the canned motor part 12 are immersed below the groundwater surface to a predetermined level.

Next, the supply of purge liquid to the purge liquid supply pipe 44 communicating between the ground and the canned motor pump is started, and at the same time, the operation of the canned motor is started. The purge liquid is 1 liter of rotor.
Each m4c of bearings 30, 32, and 34 that support this rotor shaft 28 are supplied through the center through hole 42 of l128 to lubricate the bearings, and a portion of the bearings lubricate the gap between the stator 2o and the rotor 22, which are sealed with a can. The purge liquid flows through the motor to cool the motor, and is discharged from the purge liquid discharge port 54 to the pump liquid discharge port 40 side. That is, the purge liquid is mixed with the pump discharge liquid and pumped to the ground.

On the other hand, underground water is supplied from the pump suction port 16) to the multistage pump room 1.
4a and 14b, the pump discharge port 18 passes through the m-shaped discharge passage 68, and is discharged from the tubular discharge port 4o to the discharge pipe 48. In this case, by using a variable speed control mechanism for the canned motor, it is possible to adjust the rotation speed at startup and stop, thereby realizing smooth pump operation and also making it possible to adjust the pump characteristics.

By using a stable liquid as the purge liquid, the downhole pump of this embodiment can efficiently lubricate the bearings and cool the motor, making the canned motor part more compact. can be easily realized, and it is possible to improve the heat resistance of the canned motor part and to smoothly pump up high-temperature water. In particular, the downhole pump according to the present invention has a system in which all pump liquid is discharged through a dedicated discharge pipe 48, so there is no need for a discharge passage forming means such as a seal ring inside the steel pipe through which the pump is inserted9. This has the advantage of simplifying installation and maintenance work.

3 and 4 are cross-sectional views showing another embodiment of the downhole pump according to the present invention.

That is, the pump of this embodiment has a discharge passage disposed within the canned motor section 12, as compared to the pump shown in FIG. Therefore, for convenience of explanation, the same reference numerals are given to the same components as in the pump configuration shown in FIG. 1, and detailed explanation thereof will be omitted. However, the pump of this embodiment has a pump section 1o and a canned motor section 1.
The basic configuration of the pump shown in FIG. 2 is the same as that of the pump shown in FIG.

Therefore, in the pump operation of this embodiment, a plurality of discharge pipes 56 communicating with the pump discharge ports 18 provided in the pump section 10 are connected inside the core of the stator 20, which is the inner circumference of the stator shell 21 of the canned motor section 12. It is characterized by being arranged so as to penetrate only the The configuration of the other discharge passage portions is the same as in the previous embodiment.

When installing the discharge pipe 56, as shown in FIG.
After the discharge pipe 56 is housed in the space 8, the gap is appropriately filled with backup material to reinforce it, and the instrumentation cable is housed and fixed.

In the embodiment shown in FIG. 4, the discharge pipe 56 passing through the stator 20 has a perfect circular cross section, but is not limited to this shape, and may have a rectangular or elliptical cross section, for example. It goes without saying that these can also be used as appropriate.

As an alternative, as shown in FIG. 5, a through hole 60 having the same cross-sectional shape as the discharge pipe 56 through which only the discharge pipe 56 can be inserted into the core of the stator 20 may be constructed by appropriate means. In this case, it is preferable to form the groove 62 for the instrumentation cable on the outer circumference of the core of the stator 20.The pump of this embodiment configured in this manner has a canned motor section similar to the previous embodiment. 12, the plurality of discharge pipes 56 are assembled into a single tubular discharge port 40,
Furthermore, a discharge pipe 48 is connected to this discharge pipe 40.

The other configurations are the same as the pump shown in FIG. 1 above.

〔Effect of the invention〕

As is clear from the above-mentioned embodiments, the downhole pump according to the present invention combines a canned motor and a multistage pump, and uses a dedicated purge liquid of stable quality to fill the gaps between the bearing, stator, and rotor of the canned motor. By operating the pump while supplying liquid through the liquid supply pipe, smooth pump operation can be realized while effectively achieving bearing lubrication and motor cooling. Furthermore, by using a canned motor, the pump of the present invention can strengthen the heat-resistant insulation structure, so it can be effectively used as a pump for pumping high-temperature water such as hot springs or hot water for geothermal power generation. .

In particular, the downhole pump according to the present invention has a discharge passage that guides the pump discharge fluid integrally with the canned motor section, thereby providing a sealing means for forming the discharge passage inside the steel pipe to which this pump is applied. Since it can be omitted, it is possible to eliminate various problems caused by the use of sealing means, such as the occurrence of internal circulation due to a seal failure or the inability to lift the pump due to a stuck seal, and simplify the installation and maintenance of the pump. At the same time, it is possible to realize an improvement in pump efficiency. Incidentally, among the two embodiments of the downhole pump according to the present invention described above, the embodiment shown in FIG. This is advantageous in that the passage does not affect the motor, but it is disadvantageous in that the stator has low bending stiffness and there is no instrumentation cable passage. On the other hand, the embodiment shown in FIG. 6 is suitable as a pump with a small flow rate and a large head because the flow resistance of the discharge passage is large, and there is a drawback that the passage affects the excitation characteristics of the stator. This is advantageous in that the stator has a high bending stiffness and is provided with an instrumentation cable passage.

Furthermore, the downhole pump of the present invention can achieve start and stop control that matches pump performance by variable speed control during pump operation.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Of course, various design changes can be made without departing from the spirit of the thin ice invention.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of essential parts showing an embodiment of a downhole pump according to the present invention, and FIG. 2 is a cross-sectional side view of the pump shown in FIG.
6 is a cross-sectional side view of essential parts showing another embodiment of the downhole pump not related to the present invention. FIG. 4 is a sectional view of the pump shown in FIG. FIG. 5 is a sectional view of a main part similar to FIG. 4, showing a partially modified example of the pump shown in FIG. 6. 10...Pump part 12...Canned motor part i4a, 14b...Multi-stage pump plug 16...Pump suction port 18...Pump discharge port 20
...Stake 21 ...Stator shell 22 ・
・・Rota 23 ・・Rip 24, 26
...Bearing housing 28...Rotor shaft 30.32.34...Bearing 66...Pump casing 6th...Annular discharge passage 40...Tubular discharge port 42...Through hole 44...・Purge liquid supply pipe 46...Purge liquid discharge hole 48...Discharge pipe 50...Conductive cable 52...Steel pipe 5
4...Discharge port 56...Discharge pipe 58...
Groove 60... Through hole 62... Groove 17-FIG, 1 1N Kaisho GO-111; 96 (6) FIG, 3 8 j 4 4 , -46 34゛''28 7, 42 211PI −%

Claims (1)

[Scope of Claims] (1) A pump section consisting of a single-stage or multi-stage pump chamber and a canned motor section are combined, and a pump liquid discharge passage communicating with the discharge port of the pump section is integrally provided on the outer periphery of the canned motor section. A through hole is formed in the center of the rotor shaft of the canned motor section, and the through holes are opened to communicate with each other, and a purge liquid supply pipe is connected to the one bearing, and the purge liquid supply pipe is connected to the other bearing side. A downhole pump characterized by having a purge liquid discharge port. (2. In the downhole pump according to claim 1, the pump chamber is coaxially connected to the lower end of the canned motor section, and an annular discharge passage surrounded by a pump casing is provided on the outer surface of the stator of the canned motor section. (3) In the downhole pump according to claim 1, a pump chamber is coaxially connected to the lower end of the canned motor section, and a plurality of discharge pipes are provided inside the stator of the canned motor section. (4) In the downhole pump according to any one of claims 1 to 3, the canned motor section is configured to perform variable speed control during startup and stop. pump.