Integrated motor-compressor assembly

Abstract

This integrated motor-compressor assembly (1) comprising: - a drive shaft (3), magnetic bearings (9, 10) supporting the drive shaft (3), a gas input (7), - a first compression section (4) in overhung at a first end of the drive shaft (3) and comprising a casing (4e) including a compression wheel (4c) and configured to compress a gas flowing from the gas input (7), and - a second compression section (5) at a second end of the drive shaft, the first compression section comprising a cooling fan (12) in overhung configured to supply a cooling loop (1 1) of the integrated motor-compressor assembly (1 ) with a part of the gas taken at the gas input (7), said taken part of gas being a cooling gas, the cooling fan (12) being placed between the first compression section (4) and the second compression section (5), the integrated motor-compressor assembly (1) further comprising a suction line (15) configured to provide gas from the gas input (7) to the cooling fan (12).

Description

[0001] DESCRIPTION

[0002] TITLE: INTEGRATED MOTOR-COMPRESSOR ASSEMBLY

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to an integrated motor-compressor assembly and relates in particular to a specific arrangement of a cooling fan.

[0005] DESCRIPTION OF RELATED ART

[0006] An integrated motor-compressor assembly may comprise an electric motor mounted on a drive shaft to drive the said shaft. The drive shaft is generally supported in rotation by two magnetic bearings arranged on each side of the electric motor.

[0007] A compression section may be arranged at each end of the drive shaft.

[0008] The electric motor and the magnetic bearings are subj ected to losses generated for example by eddy currents.

[0009] In order to cool the electric motor and the magnetic bearings, the integrated motor-compressor assembly comprises a cooling loop comprising a filtering device filtering a part of a gas compressed by a first compression section, the part of compressed gas being the cooling gas flowing in the electric motor and the bearings .

[0010] As the pressure of the compressed gas is too high to supply the cooling loop, a control valve expends the compressed gas filtered by the filtering device to decrease the pressure of the compressed gas at a predetermined pressure.

[0011] However, in order to decrease the pressure of the cooling gas, the control valve dissipates a part of energy used to drive the first compression section to compress the gas so that the efficiency of the integrated motor-compressor assembly is deteriorated.

[0012] Further, the control valve is a pressure regulated component which may be defective decreasing the reliability of the integrated motor-compressor assembly.

[0013] Current solution with two overhung impellers symmetrically disposed from competition (one each side of rotor) uses control valve for motor cooling with associated excessive compression work for circulating flow.

[0014] No known concept describes a usable solution using a fan with an attachment on the other side of the rotor.

[0015] There is a need to avoid at least some of the previously-mentioned drawbacks.

[0016] SUMMARY

[0017] According to an aspect, an integrated motor-compressor assembly is proposed.

[0018] The integrated motor-compressor assembly comprises a drive shaft, magnetic bearings supporting the drive shaft, an axial gas input, a first compression section comprising an axial gas input and in overhung at a first end of the drive shaft and comprising a casing including a compression wheel and configured to compress a gas flowing from the gas input, and a second compression section comprising an axial gas input and at a second end of the drive shaft, the first compression section comprising a cooling fan in overhung and having a fan compression wheel, the cooling fan being configured to be driven by the drive shaft to supply a cooling loop of the integrated motor-compressor assembly with a part of the gas taken at the gas input, the cooling loop being configured to cool down the magnetic bearings and an electric motor of the integrated motor compressor, said taken part of gas being a cooling gas, the cooling fan being placed between the first compression section and the second compression section and so that a high-pressure part of the compression wheel faces a low-pressure part of the fan compression wheel, or a high pressure part of the compression wheel faces a high-pressure part of the fan compression wheel.

[0019] The integrated motor-compressor assembly further comprises a suction line to provide gas from the gas input to the cooling fan.

[0020] The fan compression wheel is arranged in the casing of the first compression section and is configured to be driven by the drive shaft.

[0021] Advantageously, the integrated motor-compressor assembly further comprises an electric motor mounted on the drive shaft, the cooling loop being configured to cool down said electric motor by means of a flow of the cooling gas.

[0022] Preferably, the cooling loop includes a filtering device connected to the electric motor so that a first part of the cooling gas, filtered by said filtering device, flows through the electric motor to cool down the said electric motor.

[0023] Advantageously, the filtering device is further connected to each bearing so that a second part of the filtered cooling gas flows through the bearings to cool them down.

[0024] Advantageously, the cooling fan is configured to compress the cooling gas to supply the cooling loop of the integrated motor-compressor assembly with the compressed cooling gas and the suction line comprises a direct canal between the gas input and the low-pressure part of the fan compression wheel of the cooling fan, the filtering device comprising an input connected to a fan gas output of the cooling fan.

[0025] Preferably, the cooling fan is configured to aspirate the cooling gas and the suction line comprises a direct canal between the gas input and an input of the filtering device so that the cooling fan aspirates the filtered cooling gas heated by the electric motor.

[0026] Advantageously, the integrated motor-compressor comprises a return line and the cooling fan comprises a fan gas output, the return line connecting the fan gas output of the cooling fan and the axial gas input of the compression wheel of the first compression section.

[0027] Preferably, the return line directly connects the fan gas output of the cooling fan and the axial gas input of the compression wheel of the first compression section.

[0028] Preferably, in a more particular embodiment, the second compression section is in overhung at the second end of the drive shaft.

[0029] The integrated motor-compressor assembly may further comprise decompression labyrinths with integrated sealing means coupled to at least one of the compression sections and configured to prevent gas leaking toward the electric motor from said compression section.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features of the invention will appear on examination of the detailed description of embodiments, in no way restrictive, and the appended drawings in which:

[0031] [Fig 1 ] illustrates schematically an embodiment of an integrated motor-compressor assembly according to the invention; and

[0032] [Fig 2] illustrates schematically a second embodiment of the of the integrated motor-compressor assembly according to the invention.

[0033] DETAILED DESCRIPTION

[0034] Reference is made to Figure 1 which represents schematically a first embodiment of an integrated motor-compressor assembly 1 , comprising:

[0035] - a drive shaft 3 ,

[0036] - a gas input 7, magnetic bearings 9, 10 supporting the drive shaft 3 ,

[0037] - a first compression section 4 in overhung at a first end of the drive shaft 3 comprising a casing 4e including a compression wheel 4c and configured to compress a gas flowing from the gas input 7, and

[0038] - a second compression section 5 at a second end of the drive shaft.

[0039] The first compression section comprises a cooling fan 12 in overhung having a fan compression wheel 12a and being configured to be driven by the drive shaft 3 to supply a cooling loop 1 1 of the integrated motor-compressor assembly 1 with a part of the gas taken at the gas input 7, said taken part of gas being a cooling gas.

[0040] The cooling fan 12 is placed between the first compression section 4 and the second compression section 5 and so that a high-pressure part of the compression wheel 4c faces a low-pressure part of the fan compression wheel 12a.

[0041] A gas intended to be compressed by a compression wheel enters the low-pressure part of the compression wheel and exits the high-pressure part of the compression wheel. The pressure of the gas in the high-pressure part of the compression wheel is higher than the pressure of the said gas in the low-pressure part of the compression wheel. The cooling fan 12 is mounted on the drive shaft to supply the cooling loop 1 1 with a part of the gas taken at the gas input 7 of the integrated motor-compressor assembly 1 , said part of the gas taken at the gas input 7 of the integrated motor-compressor assembly 1 being named cooling gas.

[0042] The integrated motor-compressor assembly 1 further comprises a suction line 15 to provide gas from the gas input 7 to the cooling fan 12. Preferably the gas can be provided when the cooling fan 12 is activated.

[0043] This integrated motor-compressor assembly 1 allows to make a double overhung integrated motor-compressor assembly combined with a fan 12 in place of a control valve known form the prior art which generates a lot of pressure drop and debit drop in the assembly.

[0044] Indeed, the known use of a control valve disposed after a gas filter penalises the flow pressure and efficiency and is not known with double overhung symmetric configuration, but only for integrated motorcompressor assemblies with free shaft ends.

[0045] Advantageously, the integrated motor-compressor assembly 1 comprises an electric motor 2 mounted on the drive shaft 3 , the cooling loop 1 1 being configured to cool down said electric motor 2 by means of a flow of the cooling gas.

[0046] This solution allows to have an axial gas input 7, which is the most compact solution, and allows to have the flow circulating from the gas input 7 and axially through the first compression section 4 and through the cooling fan 12, which minimizes the gas intake and the effect on the pressure of the flow for the function of cooling the elements of the integrated motor-compressor assembly 1.

[0047] The integrated motor-compressor assembly 1 comprises a watertight casing 6 in which are placed the electric motor 2, the drive shaft 3 and the two compression sections 4,5.

[0048] The first compression section 4 is in overhung at a first end of the drive shaft 3 and the second compression section 5 is in overhung at the second end of the drive shaft 3.

[0049] Each compression section 4, 5 includes a gas input 4a, 5a and a gas output 4b, 5b. The gas input 4a is an axial gas input, and the gas input 5 a of the second compression section 5 is an axial gas input.

[0050] The axial gas input 4a of the first compression section 4 is connected to a gas input 7 of the integrated motor-compressor assembly 1 , the axial gas input 5 a of the second compression section 5 is connected to the gas output 4b of the first compression section 4 and the gas output 5b of the second compression section 5 is connected to a gas output 8 of the integrated motor-compressor assembly 1.

[0051] Each compression section 4, 5 may comprise one compression wheel 4c, 5 c.

[0052] Each compression section 4, 5 comprises sealing devices 4d, 5d to prevent gas leaking in the watertight casing 6 from the said compression section 4, 5.

[0053] The sealing devices 4d, 5d may comprise means for decompression, such as labyrinths, to avoid unintended leakages of gas flow, especially of polluted gas flow toward the electric motor 2 and / or the bearings 9, 10.

[0054] Each bearing 9, 10 comprises a radial bearing and / or an axial bearing.

[0055] Preferably, in a more particular embodiment, the second compression section 5 is in overhung at the second end of the drive shaft 3.

[0056] The integrated motor-compressor assembly 1 may for example further comprise decompression labyrinths with integrated sealing means 4d, 5d coupled to at least one of the compression sections 4, 5 and configured to prevent gas leaking toward the electric motor 2 from said compression sections 4,5.

[0057] The electric motor 2 is intended to drive the compression sections 4, 5 so that the first compression section 4 compresses a gas flowing in the gas input 7 of the integrated motor-compressor assembly 1 and delivers the compressed gas to the gas input 5a of the second compression section 5.

[0058] The electric motor 2 is further intended to drive the second compression section 5 to further compress the compressed gas delivered by the first compression section 4, the second compression section delivering the compressed gas to the gas output 8 of the integrated motor-compressor assembly 1.

[0059] The first compression section 4 may also comprise an axial gas bearing (not illustrated) configured to retain axially thanks to a shroud, and this axial bearing could also be cooled down by the cooling loop 1 1 .

[0060] The drive shaft 3 is supported by the bearings 9, 10 in the watertight casing 6.

[0061] The bearings 9, 10 may comprise gas bearings or preferably magnetic bearings.

[0062] It is assumed in the following that the bearings 9, 10 are magnetic bearings. Each magnetic bearing 9, 10 comprises a radial magnetic bearing and / or an axial magnetic bearing.

[0063] A first bearing 9 is arranged between the first compression section 4 and the electric motor 2, and a second bearing 10 is arranged between the second compression section 5 and the electric motor 2.

[0064] Overhung designates that a component of the integrated motorcompressor assembly such as the cooling fan 12, the first compression section 4 or the second compression section 5 is not located between the first and second bearings 9, 10.

[0065] The said component is positioned in overhung in respect with the first or the second bearings 9, 10.

[0066] For example, the cooling loop 1 1 includes a filtering device 13 connected to the cooling fan 12 and to the electric motor 2 so that a first part of a compressed cooling gas, filtered by said filtering device 13 , flows through said electric motor 2. In a particular embodiment, the gas can be provided to cool down said electric motor 2.

[0067] This configuration allows optimum overall efficiency from the cooling fan 12 combined with the double overhung solution allowing to have good and simple rotordynamics.

[0068] In both embodiments, as represented, the filtering device 13 may be arranged outside the watertight casing 6.

[0069] In variant, the filtering device 13 may be arranged inside the watertight casing 6. Unfiltered gas may include particles likely to damage components inside the watertight casing 6, for example to damage the bearings 9, 10, the electric motor 2.

[0070] The filtering device 13 is designed to remove these particles from the gas flowing in the gas input 7 of the integrated motorcompressor assembly 1.

[0071] The filtering device 13 may be further connected to each bearing 9, 10 so that a second part of the filtered cooling gas flows through the bearings 9, 10 to cool them down.

[0072] The first compression section 4 may comprise a casing 4e including the compression wheel 4c, the axial gas input 4a of the first compression section 4, the gas output 4b of the first compression section 4.

[0073] The cooling fan 12 may be arranged in overhung in the casing 4e of the first compression section 4.

[0074] The gas input 7 of the first compression section 4 leads to a low- pressure part of the compression wheel 4c of the first compression section 4.

[0075] The casing 4e of the first compression section 4 further comprises a fan gas output 12b exhausting the cooling gas compressed by the fan compression wheel 12a and a fan gas input 12c connected to the gas input 7 to supply the low-pressure part of the cooling fan 12 with gas.

[0076] In the first embodiment described in Figure 1 , the suction line comprises a direct canal 15 between the gas input 7 and the low-pressure part of the fan compression wheel 12a of the cooling fan 12, the filtering device 13 comprising an input 13 a connected to the fan gas output 12b of the cooling fan 12.

[0077] The direct canal 15 may comprise a pipe.

[0078] In this first embodiment, when the electric motor 2 drives the drive shaft 3 , the cooling fan 12 compresses the cooling gas to supply the cooling loop 1 1 with compressed cooling gas which enters the filtering device 13 through its input 13 a, and said filtering device 13 filters the compressed cooling gas. An output 13b of the filtering device 13 is connected to the electric motor 2 and the bearings 9, 10.

[0079] Also, in this simplest embodiment, the cooling fan 12 is installed in overhung onto the compression wheel 4c of the first compression section 4, sucks polluted air from the gas input 7 and pushes this gas into the input 13a of the filtering device 13 , which maximises the air flow efficiency and allows to have a fan incorporated on the first impeller that the first compression section 4 comprises.

[0080] Then, the filtered and compressed cooling gas flows in the electric motor 2 and the magnetic bearings 9, 10.

[0081] A first part of the compressed cooling gas filtered by the filtering device 13 may flow through the electric motor 2 to cool the electric motor 2 and a second part of the compressed cooling gas filtered by the filtering device 13 may flow through the magnetic bearings 9, 10 to cool the magnetic bearings 9, 10.

[0082] The first part of the compressed cooling gas heated by the electric motor 2 and the second part of the compressed cooling gas heated by the magnetic bearings 9, 10 flow to the gas input 7 of the integrated motor-compressor assembly 1 via an exhaust duct 14 connecting the gas input 7 to the electric motor 2 and the bearings 9, 10.

[0083] The cooling fan 12 may be designed so that the pressure at the fan gas output 12b is equal to a predetermined pressure, determined according to the cooling gas flow circulating in the electric motor 2 and in the magnetic bearings 9, 10, and according to the pressure drop in the cooling loop 1 1 .

[0084] Figure 2 represents schematically a second embodiment of the integrated motor-compressor assembly 1 .

[0085] The same references designate the same elements as previously referenced in the first embodiment of the integrated motor-compressor assembly 1 represented in figure 1.

[0086] The integrated motor-compressor assembly 1 comprises the electric motor 2, the drive shaft 3 , the first and the second compression sections 4, 5, the watertight casing 6, the gas input 7, the gas output 8 and the bearings 9, 10 arranged as described above in the first embodiment of the integrated motor-compressor assembly 1.

[0087] The integrated motor-compressor assembly 1 further comprises the cooling fan 12 in overhung and the filtering device 13 arranged in the integrated motor-compressor assembly 1 as described above.

[0088] As exposed in the following, in the second embodiment, the cooling fan 12 is intended to aspirate cooling gas.

[0089] The fan gas input 12c of the cooling fan 12 is arranged in the watertight casing 6 to aspirate gas in the watertight casing 6.

[0090] The cooling fan 12 is placed between the first compression section 4 and the second compression section 5 so that a high-pressure part of the compression wheel 4c faces a high-pressure part of the fan compression wheel 12a.

[0091] The integrated motor-compressor assembly 1 further comprises the suction line, comprising a direct canal 16 between the gas input 7 and an input 13 a of the filtering device 13 so that the cooling fan 12 aspirates the filtered cooling gas heated by the electric motor 2.

[0092] The direct canal 16 may comprise a pipe.

[0093] The integrated motor-compressor assembly 1 further comprises a return line 17 connecting the fan gas output 12b of the cooling fan 12 and the axial gas input 4a of the compression wheel 4c of the first compression section 4.

[0094] The return line 17 may directly connect the fan gas output 12b of the cooling fan 12 and the axial gas input 4a of the compression wheel of the first compression section 4 so that no other element is arranged on the return line 17. Preferably, the return line directly connects the fan gas output 12b of the cooling fan 12 and the axial gas input 4a of the compression wheel of the first compression section 4.

[0095] In this second embodiment, when the electric motor 2 drives the drive shaft 3, the cooling fan 12 sucks the cooling gas from the input 7 through the electric motor 2, the bearings 9, 10 and the filtering device 13 , to supply the cooling loop 1 1 with compressed cooling gas which enters first in the filtering device 13 through its input 13 a, which filters the compressed cooling gas directly before it is in contact with the fan 12, unlike in the first embodiment.

[0096] In this second embodiment, the cooling fan 12 sucks filtered gas from the output 13b of the filtering device 13 through the electric motor 2 instead of pushing it like in the first embodiment, then repels it back to the axial gas input 4a of the first compression section 4.

[0097] The filtered air (cooling gas) delivered flowing from the output 13b of the filtering device 13 flows through the electric motor 2 and the magnetic bearings 9, 10, following the depression created by the cooling fan 12, and is heated by the electric motor 2 and the magnetic bearings 9, 10.

[0098] The heated cooling gas is sucked by the fan gas input 12c of the cooling fan 12 and conveyed by the cooling fan 12 in the return line 17 connecting the fan gas output 12b of the cooling fan 12 to the axial gas input 4a of the first compression section 4.

[0099] This embodiment allows to have the fan function integrated into the first compression section 4 or installed as a separated component between the first compression section 4 and the electric motor 2, and to have it work in aspiration instead of compression, thus having the cooling gas flow filtered directly at the beginning of the cooling loop 1 1 , which prevents the premature deterioration of components.

[0100] The two proposed architectures described above allow to arrange a cooling fan in a double overhung integrated motor-compressor assembly between the two compression sections of the integrated motor-compressor assembly. The fan compression wheel is arranged in the casing of the first compression section so that the cooling fan is integrated in a compact manner in the watertight casing 6 compared to a cooling fan comprising a fan compression wheel which is not arranged in the said casing.

Claims

CLAIMS1. Integrated motor-compressor assembly ( 1 ) comprising: a drive shaft (3), magnetic bearings (9, 10) supporting the drive shaft (3), an axial gas input (7), a first compression section (4) comprising an axial gas input and in overhung at a first end of the drive shaft (3) and comprising a casing (4e) including a compression wheel (4c) and configured to compress a gas flowing from the gas input (7), and a second compression section (5) comprising an axial gas input and at a second end of the drive shaft, the first compression section comprising a cooling fan ( 12) in overhung and having a fan compression wheel ( 12a), the cooling fan being configured to be driven by the drive shaft (3) to supply a cooling loop (1 1) of the integrated motor-compressor assembly (1 ) with a part of the gas taken at the gas input (7), the cooling loop being configured to cool down the magnetic bearings and an electric motor of the integrated motor compressor, said taken part of gas being a cooling gas, the cooling fan ( 12) being placed between the first compression section (4) and the second compression section (5) and so that a high-pressure part of the compression wheel (4c) faces a low-pressure part of the fan compression wheel (12a) or a high pressure part of the compression wheel (4c) faces a high-pressure part of the fan compression wheel ( 12a), wherein the integrated motorcompressor assembly (1 ) further comprises a suction line ( 15 , 16) to provide gas from the gas input (7) to the cooling fan ( 12) and the fan compression wheel (12a) is arranged in the casing (4e) of the first compression section (4) and is configured to be driven by the drive shaft (3).

2. Integrated motor-compressor assembly ( 1 ) according to claim 1 , further comprising an electric motor (2) mounted on the drive shaft (3), the cooling loop ( 1 1 ) being configured to cool down said electric motor (2) by means of a flow of the cooling gas.

3. Integrated motor-compressor assembly ( 1 ) according to claim 2, wherein the cooling loop ( 1 1 ) includes a filtering device ( 13) connected to the electric motor (2) so that a first part of the cooling gas, filtered by said filtering device ( 13), flows through the electric motor (2) to cool down said electric motor (2).

4. Integrated motor-compressor assembly ( 1 ) according to claim2 or 3 , wherein the filtering device ( 13) is further connected to each bearing (9, 10) so that a second part of the filtered cooling gas flows through the bearings (9, 10) to cool them down.

5. Integrated motor-compressor assembly ( 1 ) according to claim3 or 4, wherein the cooling fan ( 12) is configured to compress the cooling gas to supply the cooling loop ( 1 1 ) of the integrated motor-compressor assembly with the compressed cooling gas and the suction line comprises a direct canal ( 15) between the axial gas input (7) and the low-pressure part of the fan compression wheel (12a) of the cooling fan ( 12), the filtering device (13) comprising an input (13a) connected to a fan gas output (12b) of the cooling fan (12).

6. Integrated motor-compressor assembly ( 1 ) according to claim 3 or 4, wherein the cooling fan ( 12) is configured to aspirate the cooling gas and the suction line comprises a direct canal ( 16) between the gas input (7) and an input (13 a) of the filtering device ( 13) so that the cooling fan (12) aspirates the filtered cooling gas heated by the electric motor (2).

7. Integrated motor-compressor assembly ( 1 ) according to claim6, wherein the integrated motor-compressor assembly comprises a return line ( 17) and the cooling fan (12) comprises a fan gas output (12b), the return line ( 17) connecting the fan gas output (12b) of the cooling fan ( 12) and the axial gas input (4a) of the compression wheel of the first compression section (4).

8. Integrated motor-compressor assembly ( 1 ) according to claim7, wherein the return line ( 17) directly connects the fan gas output (12b) of the cooling fan ( 12) and the axial gas input (4a) of the compression wheel (4c) of the first compression section (4).

9. Integrated motor-compressor assembly ( 1 ) according to any of the claims 1 to 8, further comprising decompression labyrinths withintegrated sealing means (4d,5d) coupled to at least one of the compression sections (4,5) and configured to prevent gas leaking toward the electric motor (2) from said compression section (4,5).

10. Integrated motor-compressor assembly according to any one of the preceding claims, wherein, the second compression section (5) is in overhung at the second end of the drive shaft (3).

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