EP3088656B1 - Downhole compressor - Google Patents
Downhole compressor Download PDFInfo
- Publication number
- EP3088656B1 EP3088656B1 EP16159927.9A EP16159927A EP3088656B1 EP 3088656 B1 EP3088656 B1 EP 3088656B1 EP 16159927 A EP16159927 A EP 16159927A EP 3088656 B1 EP3088656 B1 EP 3088656B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- rotor
- impeller
- downhole compressor
- compressor
- downhole
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Not-in-force
Links
- 238000007789 sealing Methods 0.000 claims description 15
- 230000001105 regulatory effect Effects 0.000 claims description 9
- 238000006073 displacement reaction Methods 0.000 claims description 7
- 238000004891 communication Methods 0.000 claims description 5
- 238000011144 upstream manufacturing Methods 0.000 claims description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 24
- 239000007789 gas Substances 0.000 description 12
- 239000003345 natural gas Substances 0.000 description 12
- 239000012530 fluid Substances 0.000 description 10
- 239000000314 lubricant Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000020169 heat generation Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000005549 size reduction Methods 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000005461 lubrication Methods 0.000 description 2
- 239000002343 natural gas well Substances 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/12—Methods or apparatus for controlling the flow of the obtained fluid to or in wells
- E21B43/121—Lifting well fluids
- E21B43/128—Adaptation of pump systems with down-hole electric drives
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D25/00—Pumping installations or systems
- F04D25/02—Units comprising pumps and their driving means
- F04D25/06—Units comprising pumps and their driving means the pump being electrically driven
- F04D25/0606—Units comprising pumps and their driving means the pump being electrically driven the electric motor being specially adapted for integration in the pump
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/05—Shafts or bearings, or assemblies thereof, specially adapted for elastic fluid pumps
- F04D29/051—Axial thrust balancing
- F04D29/0516—Axial thrust balancing balancing pistons
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/05—Shafts or bearings, or assemblies thereof, specially adapted for elastic fluid pumps
- F04D29/056—Bearings
- F04D29/058—Bearings magnetic; electromagnetic
Definitions
- the present invention relates to a downhole compressor, and particularly relates to a downhole compressor suitable for securing reliability at the time of high-speed rotation.
- a downhole compressor installed inside a natural gas well and adapted to assist production of natural gas is installed inside a borehole having a diameter of approximately several centimeters, size reduction of the device is needed.
- a gas production amount may be reduced because a flow passage cross-sectional area is reduced.
- centrifugal force used for gas compression is reduced due to reduction of an outer diameter size of an impeller due to size reduction of the compressor. Therefore, there may be possibility that a pressure ratio is reduced and sufficient pressure cannot be obtained for gas production.
- a rotational speed of a rotor is required to be accelerated in the downhole compressor in order to compensate such a reduced flow rate and reduced pressure ratio caused by size reduction.
- a gas flow rate is increased because a flow speed is increased by accelerating rotation of the rotor.
- the pressure ratio is increased because the centrifugal force is increased by acceleration.
- a downhole compressor disclosed in US Patent No. 7,338,262 is operated at a high rotational speed of 20,000 rpm to 50,000 rpm.
- a thrust load acting on the impeller may be increased due to mixture of the foreign matters inside the natural gas.
- load capacity is generally small compared to an oil bearing and the like. Therefore, it is difficult to design a bearing that can handle a large thrust load caused by mixture of the foreign matters.
- the present invention is directed to providing a downhole compressor in which reliability can be secured at the time of high-speed rotation even when natural gas properties are changed due to mixture of foreign matters and the like.
- the present invention provides a downhole compressor, including: a casing disposed inside a well; a rotor built inside the casing; and an impeller disposed at the rotor, wherein an electromagnetic control unit configured to electromagnetically control a relative position of the rotor inside the casing is provided.
- the present invention is the downhole compressor characterized in including a bearingless motor as an electromagnetic control unit.
- the present invention is the downhole compressor characterized in that the electromagnetic control unit includes a magnetic bearing.
- the present invention is the downhole compressor characterized in that a pressure regulating chamber is provided at a back surface portion of the impeller, a shaft sealing device is provided between an outlet portion of the impeller and the pressure regulating chamber, and a communication unit is provided between the pressure regulating chamber and an inlet portion of the impeller.
- the present invention is the downhole compressor characterized in that a displacement meter to measure axial displacement of the rotor is provided, and the displacement meter is disposed at the back surface portion of the impeller.
- the present invention is the downhole compressor characterized in that a leakage amount at the shaft sealing device is reduced when the rotor is displaced to an axial upstream side.
- the present invention is the downhole compressor characterized in that the shaft sealing device includes axial clearance, and the axial clearance is reduced when the rotor is displaced to the axial upstream side.
- the present invention is the downhole compressor characterized in that a control device for the electromagnetic control unit is disposed on the ground.
- the present invention is the downhole compressor characterized in that an operating condition is determined by using a control signal of the electromagnetic control unit.
- the rotor can be supported by electromagnetically controlling a position of the rotor without using lubricant such as natural gas. Therefore, deterioration of reliability of the bearing caused by heat generation of the lubricant can be prevented. Further, reliability of the device can be stably secured because there is no effect on supporting characteristics from change of the natural gas properties.
- Fig. 1 is a cross-sectional view illustrating a main portion of a downhole compressor according to a first embodiment of the present invention.
- An impeller 3 is disposed at an end portion of a rotor 2, and natural gas is pressurized by rotation of the rotor 2.
- a thrust load generated at the impeller 3 is supported by a thrust bearing not illustrated.
- a bearingless motor 4 disposed at center of the rotor 2 generates drive torque at the rotor 2 and simultaneously supports the rotor 2 by generating electromagnetic force such that relative positions between the rotor 2 and a casing not illustrated is kept substantially constant. Since the position of the rotor 2 is electromagnetically controlled, supporting characteristics of the rotor 2 do not change even when the natural gas properties are changed, and the rotor 2 can be stably supported.
- Fig. 2 is a cross-sectional view illustrating an installation state of the downhole compressor 1 according to the present embodiment.
- the downhole compressor 1 is installed inside a natural gas well 5.
- a controller 6 of the bearingless motor 4 is disposed on the ground 15, and the downhole compressor 1 and the controller 6 are connected via a cable 7. Since the controller 6 is disposed on the ground 15, a control signal of the bearingless motor 4 can be easily extracted and used for setting an operating condition of the downhole compressor 1.
- Electromagnetic control force to control the position of the rotor 2 inside the casing of the downhole compressor 1 is proportional to the square of control current. Therefore, dynamic fluid force that acts on the rotor 2 can be grasped by monitoring the control current.
- the natural gas properties and unsteadiness thereof can be estimated by collating the fluid force, operating characteristics of the impeller 3, drive torque, rotational speed, and so on.
- An operating condition such as the rotational speed can be appropriately set by collating the estimated gas properties and operating characteristics of the impeller 3, and excessive fluid force that may act on the impeller 3 and unstable phenomena of the fluid can be prevented. For example, in the case where the fluid force is increased by increased liquid content inside the gas, the fluid force can be decreased by reducing the rotational speed of the rotor 2, and reliability of the device can be secured.
- FIG. 3 is a cross-sectional view illustrating a main portion of a downhole compressor 1 according to the present embodiment.
- a component denoted by a reference sign same as a first embodiment has the same structure and effects. Therefore, a description therefor will be omitted and only a different point from the above-described first embodiment will be described.
- a motor 8 is disposed as a unit to generate drive torque at a rotor 2 instead of a bearingless motor 4.
- a magnetic bearing 9 disposed at a casing not illustrated is used instead of the bearingless motor 4.
- radial magnetic bearings 9a to support a load in an axial orthogonal direction are disposed.
- a thrust collar 10 to transmit a thrust load is disposed between the motor 8 and the impeller 3, and thrust magnetic bearings 9b are disposed on both sides of the thrust collar 10.
- a displacement sensor and an electromagnetic actuator are built inside the magnetic bearing 9, and electromagnetic force is controlled such the position of the rotor 2 inside the casing is kept substantially constant. Load capacity can be increased by using the magnetic bearing 9 independent from the motor 8, and reliability can be improved.
- Fig. 4 is a cross-sectional view illustrating a main portion of a downhole compressor 1 according to the present embodiment.
- a component denoted by a reference sign same as above-described embodiments has the same structure and effects. Therefore, a description therefor will be omitted and only a different point from the above-described embodiments will be described.
- pressure in a flow passage portion of an impeller 3 is increased from an inlet portion 3b to an outlet portion 3a, but pressure on a back surface of the impeller 3 is substantially equal to the pressure at the outlet portion 3a of the impeller 3.
- a thrust load is generated at the impeller 3 in a direction from the back surface side to a flow passage side.
- Load capacity of a magnetic bearing 9 is small compared with a general oil lubrication bearing. Therefore, in the case of applying the magnetic bearing 9 in the downhole compressor 1, the thrust load is preferably reduced as much as possible.
- a shaft sealing device 12 is disposed at a back surface portion of the impeller 3 and forms a pressure regulating chamber 11. Further, a communication unit 13 is provided between the pressure regulating chamber 11 and the inlet portion 3b of the impeller 3 and decreases pressure at the pressure regulating chamber 11. As a result, the thrust load can be reduced by decreasing the pressure at the back surface of the impeller 3, and reliability of a thrust magnetic bearing 9b can be improved.
- axial clearance of the shaft sealing device 12 is preferably kept constant. Therefore, a position sensor 14 for an axial rotor 2 used to control the thrust magnetic bearing 9b is provided at the back surface portion of the impeller 3, and the thrust magnetic bearing 9b is controlled so as to keep the clearance of shaft sealing device 12 constant.
- an axial groove is provided as the communication unit 13 at a fixing portion of the impeller 3 of the rotor 2.
- the axial groove may also be provided on the impeller 3 side and a communication hole may be provided at the rotor 2 and the impeller 3.
- Fig. 5 is a cross-sectional view illustrating a main portion of a downhole compressor 1 according to the present embodiment.
- a component denoted by a reference sign same as above-described embodiments has the same structure and effects. Therefore, a description therefor will be omitted and only a different point from the above-described embodiments will be described.
- a shaft sealing device 12 is disposed at an outer diameter portion of an impeller 3.
- the shaft sealing device 12 includes a so-called labyrinth seal 12a opposing to an outer periphery of the impeller 3 and an axial clearance 12b projecting to a flow passage side of the impeller 3.
- a leakage amount at the shaft sealing device 12 is increased, back pressure of the impeller 3 is increased and a thrust load is increased, thereby moving a rotor 2 to an axial upstream side.
- the axial clearance 12b at the shaft sealing device 12 becomes small, and the leakage amount is reduced at the shaft sealing device 12. Therefore, the thrust load is reduced and the rotor 2 is pushed back to an axial downstream side. Since the thrust load is thus automatically adjusted in accordance with movement of the rotor 2, the thrust load that acts on a thrust magnetic bearing 9b can be properly adjusted and reliability of the device can be improved.
- the thrust magnetic bearing 9b can be controlled so as to keep the clearance at the shaft sealing device 12 constant by providing a position sensor 14 at an axial rotor 2 illustrated in the third embodiment.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Environmental & Geological Engineering (AREA)
- Electromagnetism (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
- Magnetic Bearings And Hydrostatic Bearings (AREA)
- Sealing Of Bearings (AREA)
Description
- The present invention relates to a downhole compressor, and particularly relates to a downhole compressor suitable for securing reliability at the time of high-speed rotation.
- Since a downhole compressor installed inside a natural gas well and adapted to assist production of natural gas is installed inside a borehole having a diameter of approximately several centimeters, size reduction of the device is needed. When the size of the compressor is reduced, a gas production amount may be reduced because a flow passage cross-sectional area is reduced. Further, in the case of adopting a centrifugal compressor as a form of the compressor, centrifugal force used for gas compression is reduced due to reduction of an outer diameter size of an impeller due to size reduction of the compressor. Therefore, there may be possibility that a pressure ratio is reduced and sufficient pressure cannot be obtained for gas production.
- A rotational speed of a rotor is required to be accelerated in the downhole compressor in order to compensate such a reduced flow rate and reduced pressure ratio caused by size reduction. In other words, a gas flow rate is increased because a flow speed is increased by accelerating rotation of the rotor. Further, the pressure ratio is increased because the centrifugal force is increased by acceleration. For instance, a downhole compressor disclosed in
US Patent No. 7,338,262 , is operated at a high rotational speed of 20,000 rpm to 50,000 rpm. - In a general industrial turbo machine, an oil lubrication sliding bearing and a rolling bearing are widely used. However, in a high-speed rotary machine such as a downhole compressor, these general bearings are hardly applied because an amount of heat generation at the bearings is excessively large. As a countermeasure to such a phenomenon, the above-described known art adopts, for example, a static pressure gas bearing in which natural gas is pressurized and then used. In the gas bearing, heat generation of the lubricant can be kept low because viscosity of the gas that is the lubricant is extremely low compared to viscosity of liquid such as oil, and it can be considered that reliability of the bearing can be secured.
- In natural gas inside a borehole, foreign matters such as liquid like water and oil and solids like earth and sand may be mixed some times. In the case of using the natural gas as lubricant, such mixture of the foreign matters causes increase of heat generation and physical damages, and reliability of the bearing may be degraded. Such foreign matters may be reduced by a structure using a separator or the like, but there may be possibility that the foreign matters cannot be completely removed and reliability of the bearing may not be sufficiently secured.
- On the other hand, when the foreign matters are mixed inside the natural gas used as working fluid of the compressor, properties such as density and viscosity of the fluid are changed. Therefore, when the compressor is operated without considering such mixture of the foreign matters, there is concern that deterioration of operation efficiency, generation of excessive fluid force, occurrence of unstable phenomena in the fluid, and the like may be caused by change of operating characteristics of an impeller. In the downhole compressor using the gas bearing, such change of the gas properties can be hardly detected, and there may be possibility that sufficient reliability of a device cannot be secured.
- Further, a thrust load acting on the impeller may be increased due to mixture of the foreign matters inside the natural gas. In a high-speed bearing such as the gas bearing, load capacity is generally small compared to an oil bearing and the like. Therefore, it is difficult to design a bearing that can handle a large thrust load caused by mixture of the foreign matters.
- In view of the above-described situations, the present invention is directed to providing a downhole compressor in which reliability can be secured at the time of high-speed rotation even when natural gas properties are changed due to mixture of foreign matters and the like.
- To achieve the above-described object, the present invention provides a downhole compressor, including: a casing disposed inside a well; a rotor built inside the casing; and an impeller disposed at the rotor, wherein an electromagnetic control unit configured to electromagnetically control a relative position of the rotor inside the casing is provided.
- Further, the present invention is the downhole compressor characterized in including a bearingless motor as an electromagnetic control unit.
- Furthermore, the present invention is the downhole compressor characterized in that the electromagnetic control unit includes a magnetic bearing.
- Furthermore, the present invention is the downhole compressor characterized in that a pressure regulating chamber is provided at a back surface portion of the impeller, a shaft sealing device is provided between an outlet portion of the impeller and the pressure regulating chamber, and a communication unit is provided between the pressure regulating chamber and an inlet portion of the impeller.
- Furthermore, the present invention is the downhole compressor characterized in that a displacement meter to measure axial displacement of the rotor is provided, and the displacement meter is disposed at the back surface portion of the impeller.
- Furthermore, the present invention is the downhole compressor characterized in that a leakage amount at the shaft sealing device is reduced when the rotor is displaced to an axial upstream side.
- Furthermore, the present invention is the downhole compressor characterized in that the shaft sealing device includes axial clearance, and the axial clearance is reduced when the rotor is displaced to the axial upstream side.
- Furthermore, the present invention is the downhole compressor characterized in that a control device for the electromagnetic control unit is disposed on the ground.
- Furthermore, the present invention is the downhole compressor characterized in that an operating condition is determined by using a control signal of the electromagnetic control unit.
- According to the present invention, the rotor can be supported by electromagnetically controlling a position of the rotor without using lubricant such as natural gas. Therefore, deterioration of reliability of the bearing caused by heat generation of the lubricant can be prevented. Further, reliability of the device can be stably secured because there is no effect on supporting characteristics from change of the natural gas properties.
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Fig. 1 is a cross-sectional view illustrating a main portion of a downhole compressor according to a first embodiment of the present invention; -
Fig. 2 is a cross-sectional view illustrating an installation state of the downhole compressor according to the first embodiment of the present invention; -
Fig. 3 is a cross-sectional view illustrating a main portion of a downhole compressor according to a second embodiment of the present invention; -
Fig. 4 is a cross-sectional view illustrating a main portion of a downhole compressor according to a third embodiment of the present invention; and -
Fig. 5 is a cross-sectional view illustrating a main portion of a downhole compressor according to a fourth embodiment of the present invention. - Embodiments to implement the present invention will be described below using the drawings.
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Fig. 1 is a cross-sectional view illustrating a main portion of a downhole compressor according to a first embodiment of the present invention. - An
impeller 3 is disposed at an end portion of arotor 2, and natural gas is pressurized by rotation of therotor 2. A thrust load generated at theimpeller 3 is supported by a thrust bearing not illustrated. Abearingless motor 4 disposed at center of therotor 2 generates drive torque at therotor 2 and simultaneously supports therotor 2 by generating electromagnetic force such that relative positions between therotor 2 and a casing not illustrated is kept substantially constant. Since the position of therotor 2 is electromagnetically controlled, supporting characteristics of therotor 2 do not change even when the natural gas properties are changed, and therotor 2 can be stably supported. -
Fig. 2 is a cross-sectional view illustrating an installation state of thedownhole compressor 1 according to the present embodiment. Thedownhole compressor 1 is installed inside a natural gas well 5. Acontroller 6 of thebearingless motor 4 is disposed on theground 15, and thedownhole compressor 1 and thecontroller 6 are connected via acable 7. Since thecontroller 6 is disposed on theground 15, a control signal of thebearingless motor 4 can be easily extracted and used for setting an operating condition of thedownhole compressor 1. - Electromagnetic control force to control the position of the
rotor 2 inside the casing of thedownhole compressor 1 is proportional to the square of control current. Therefore, dynamic fluid force that acts on therotor 2 can be grasped by monitoring the control current. The natural gas properties and unsteadiness thereof can be estimated by collating the fluid force, operating characteristics of theimpeller 3, drive torque, rotational speed, and so on. An operating condition such as the rotational speed can be appropriately set by collating the estimated gas properties and operating characteristics of theimpeller 3, and excessive fluid force that may act on theimpeller 3 and unstable phenomena of the fluid can be prevented. For example, in the case where the fluid force is increased by increased liquid content inside the gas, the fluid force can be decreased by reducing the rotational speed of therotor 2, and reliability of the device can be secured. - A second embodiment of the present invention will be described using
Fig. 3. Fig. 3 is a cross-sectional view illustrating a main portion of adownhole compressor 1 according to the present embodiment. In a structure of the present embodiment, a component denoted by a reference sign same as a first embodiment has the same structure and effects. Therefore, a description therefor will be omitted and only a different point from the above-described first embodiment will be described. - In the present embodiment, a
motor 8 is disposed as a unit to generate drive torque at arotor 2 instead of abearingless motor 4. Further, as an electromagnetic control unit for a position of therotor 2, a magnetic bearing 9 disposed at a casing not illustrated is used instead of thebearingless motor 4. On both sides of themotor 8, radialmagnetic bearings 9a to support a load in an axial orthogonal direction are disposed. Further, athrust collar 10 to transmit a thrust load is disposed between themotor 8 and theimpeller 3, and thrustmagnetic bearings 9b are disposed on both sides of thethrust collar 10. A displacement sensor and an electromagnetic actuator are built inside the magnetic bearing 9, and electromagnetic force is controlled such the position of therotor 2 inside the casing is kept substantially constant. Load capacity can be increased by using the magnetic bearing 9 independent from themotor 8, and reliability can be improved. - Next, a third embodiment of the present invention will be described using
Fig. 4 . -
Fig. 4 is a cross-sectional view illustrating a main portion of adownhole compressor 1 according to the present embodiment. In a structure of the present embodiment, a component denoted by a reference sign same as above-described embodiments has the same structure and effects. Therefore, a description therefor will be omitted and only a different point from the above-described embodiments will be described. According to the second embodiment illustrated inFig. 3 , pressure in a flow passage portion of animpeller 3 is increased from aninlet portion 3b to anoutlet portion 3a, but pressure on a back surface of theimpeller 3 is substantially equal to the pressure at theoutlet portion 3a of theimpeller 3. Therefore, a thrust load is generated at theimpeller 3 in a direction from the back surface side to a flow passage side. Load capacity of a magnetic bearing 9 is small compared with a general oil lubrication bearing. Therefore, in the case of applying the magnetic bearing 9 in thedownhole compressor 1, the thrust load is preferably reduced as much as possible. - According to the third embodiment, a
shaft sealing device 12 is disposed at a back surface portion of theimpeller 3 and forms apressure regulating chamber 11. Further, acommunication unit 13 is provided between thepressure regulating chamber 11 and theinlet portion 3b of theimpeller 3 and decreases pressure at thepressure regulating chamber 11. As a result, the thrust load can be reduced by decreasing the pressure at the back surface of theimpeller 3, and reliability of a thrustmagnetic bearing 9b can be improved. - Further, in order to stabilize the thrust load in the present embodiment, axial clearance of the
shaft sealing device 12 is preferably kept constant. Therefore, aposition sensor 14 for anaxial rotor 2 used to control the thrustmagnetic bearing 9b is provided at the back surface portion of theimpeller 3, and the thrustmagnetic bearing 9b is controlled so as to keep the clearance ofshaft sealing device 12 constant. - Additionally, according to the present embodiment, an axial groove is provided as the
communication unit 13 at a fixing portion of theimpeller 3 of therotor 2. The axial groove may also be provided on theimpeller 3 side and a communication hole may be provided at therotor 2 and theimpeller 3. - Next, a fourth embodiment of the present invention will be described using
Fig. 5 . -
Fig. 5 is a cross-sectional view illustrating a main portion of adownhole compressor 1 according to the present embodiment. In a structure of the present embodiment, a component denoted by a reference sign same as above-described embodiments has the same structure and effects. Therefore, a description therefor will be omitted and only a different point from the above-described embodiments will be described. - According to the present embodiment, a
shaft sealing device 12 is disposed at an outer diameter portion of animpeller 3. Theshaft sealing device 12 includes a so-calledlabyrinth seal 12a opposing to an outer periphery of theimpeller 3 and anaxial clearance 12b projecting to a flow passage side of theimpeller 3. When a leakage amount at theshaft sealing device 12 is increased, back pressure of theimpeller 3 is increased and a thrust load is increased, thereby moving arotor 2 to an axial upstream side. At this point, theaxial clearance 12b at theshaft sealing device 12 becomes small, and the leakage amount is reduced at theshaft sealing device 12. Therefore, the thrust load is reduced and therotor 2 is pushed back to an axial downstream side. Since the thrust load is thus automatically adjusted in accordance with movement of therotor 2, the thrust load that acts on a thrustmagnetic bearing 9b can be properly adjusted and reliability of the device can be improved. - Meanwhile, in the fourth embodiment also, the thrust
magnetic bearing 9b can be controlled so as to keep the clearance at theshaft sealing device 12 constant by providing aposition sensor 14 at anaxial rotor 2 illustrated in the third embodiment. - Features, components and specific details of the structures of the above-described embodiments may be exchanged or combined to form further embodiments optimized for the respective application. As far as those modifications are readily apparent for an expert skilled in the art they shall be disclosed implicitly by the above description without specifying explicitly every possible combination, for the sake of conciseness of the present description.
Claims (9)
- A downhole compressor (1), comprising:a casing disposed inside a well;a rotor (2) built inside the casing; andan impeller (3) disposed at the rotor (2), characterised in that an electromagnetic control unit is configured to electromagnetically control a relative position of the rotor (2) inside the casing is provided.
- The downhole compressor (1) according to claim 1, wherein a bearingless motor (4) is provided as the electromagnetic control unit.
- The downhole compressor (1) according to claim 1, wherein a magnetic bearing is provided as the electromagnetic control unit.
- The downhole compressor (1) according to claim 1, wherein
a pressure regulating chamber is provided at a back surface portion of the impeller (3),
a shaft sealing device is provided between an outlet portion of the impeller (3) and the pressure regulating chamber, and
a communication unit is provided between the pressure regulating chamber and an inlet portion of the impeller (3). - The downhole compressor (1) according to claim 1 or 4, wherein
a displacement meter configured to measure axial displacement is provided, and
the displacement meter is disposed at a back surface portion of the impeller (3). - The downhole compressor (1) according to claim 4, wherein a leakage amount at the shaft sealing device is reduced when the rotor (2) is displaced to an axial upstream side.
- The downhole compressor (1) according to claim 6, wherein the shaft sealing device includes axial clearance, and the axial clearance is reduced when the rotor (2) is displaced to the axial upstream side.
- The downhole compressor (1) according to claim 1, wherein a control device for the electromagnetic control unit is disposed on the ground.
- The downhole compressor (1) according to claim 1 or 8, wherein an operating condition is determined by using a control signal of the electromagnetic control unit.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2015054152A JP6389785B2 (en) | 2015-03-18 | 2015-03-18 | Downhole compressor |
Publications (2)
Publication Number | Publication Date |
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EP3088656A1 EP3088656A1 (en) | 2016-11-02 |
EP3088656B1 true EP3088656B1 (en) | 2018-01-17 |
Family
ID=55640526
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP16159927.9A Not-in-force EP3088656B1 (en) | 2015-03-18 | 2016-03-11 | Downhole compressor |
Country Status (3)
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US (1) | US20160273324A1 (en) |
EP (1) | EP3088656B1 (en) |
JP (1) | JP6389785B2 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10465489B2 (en) * | 2016-12-28 | 2019-11-05 | Upwing Energy, LLC | Downhole blower system with passive radial bearings |
JP6447662B2 (en) * | 2017-05-09 | 2019-01-09 | ダイキン工業株式会社 | Electric motor system and turbo compressor provided with the same |
TWI696761B (en) * | 2018-11-14 | 2020-06-21 | 財團法人工業技術研究院 | Magnetic bearing centrifugal compressor and controlling method thereof |
WO2022222563A1 (en) * | 2021-04-19 | 2022-10-27 | 青岛海尔生物医疗科技有限公司 | Centrifuge |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS56113101U (en) * | 1980-02-01 | 1981-09-01 | ||
US5355042A (en) * | 1988-09-09 | 1994-10-11 | University Of Virginia Patent Foundation | Magnetic bearings for pumps, compressors and other rotating machinery |
US5605193A (en) * | 1995-06-30 | 1997-02-25 | Baker Hughes Incorporated | Downhole gas compressor |
JP2001254693A (en) * | 2000-03-09 | 2001-09-21 | Tokyo Buhin Kogyo Co Ltd | Magnetic levitation type seal-less pump |
GB2362901B (en) * | 2000-06-03 | 2004-03-31 | Weir Pumps Ltd | Downhole gas compression |
GB2384274A (en) * | 2002-01-16 | 2003-07-23 | Corac Group Plc | Downhole compressor with electric motor and gas bearings |
EP1895180A2 (en) * | 2006-08-30 | 2008-03-05 | Ebara Corporation | Magnetic bearing device, rotating system therewith and method of identification of the model of the main unit in a rotating system |
EP2677177B1 (en) * | 2012-06-22 | 2020-10-14 | Skf Magnetic Mechatronics | Electric centrifugal compressor for vehicles |
US20140271270A1 (en) * | 2013-03-12 | 2014-09-18 | Geotek Energy, Llc | Magnetically coupled expander pump with axial flow path |
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2015
- 2015-03-18 JP JP2015054152A patent/JP6389785B2/en not_active Expired - Fee Related
-
2016
- 2016-02-25 US US15/053,274 patent/US20160273324A1/en not_active Abandoned
- 2016-03-11 EP EP16159927.9A patent/EP3088656B1/en not_active Not-in-force
Non-Patent Citations (1)
Title |
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None * |
Also Published As
Publication number | Publication date |
---|---|
JP6389785B2 (en) | 2018-09-12 |
EP3088656A1 (en) | 2016-11-02 |
US20160273324A1 (en) | 2016-09-22 |
JP2016173084A (en) | 2016-09-29 |
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