Compression Apparatus

Abstract

Provided is a compression apparatus that can appropriately cool a motor even in a high-temperature operation environment. A rotating shaft, a main compressor attached to the rotating shaft, and which compresses ambient gases and to emit a compressed gas, a motor attached to an upstream side of the main compressor on the rotating shaft, and which drives the main compressor, a turbine provided at the upstream side of the main compressor, and which expands a part of the ambient gas to generate a low-temperature gas to be used to cool the motor, and a sub compressor provided at the upstream side of the main compressor and at a downstream side of the turbine, and which compresses the low-temperature gas used to cool the motor to pressure equal to the ambient gas, wherein the main compressor generates the compressed gas by mixing and compressing the low-temperature gas compressed by the sub compressor and a part of the remaining ambient gas.

Description

TECHNICAL FIELD

The present invention relates to a compression apparatus, and especially relates to a compression apparatus used in a high-temperature environment.

BACKGROUND ART

In natural gas fields, gas wells that reach a gas layer from the ground are developed, and a natural gas accumulated in the gas layer is caused to flow in an artesian manner and is collected. In the beginning of the development of the gas wells, the pressure of the gas layer is high, and the natural gas can be caused to flow to the ground in an artesian manner. However, as the natural gas is continuously collected, the pressure of the gas layer is decreased, and the artesian flow stops when the pressure falls below a certain limit pressure. Therefore, conventionally, the gas field, in which the pressure of the gas layer falls below the limit pressure, is regarded to be exhausted even if a substantial amount of natural gas still remains in the gas layer.

However, methods of collecting the natural gas from the gas field where the artesian flow stops have been discussed on the background of an increase in energy price and development of mining technologies. As one of the methods, a method of installing a compression apparatus on a bottom portion of a gas well, and increasing the pressure of the natural gas in the gas layer and sending the natural gas to the ground has been suggested, and research and development of the compression apparatus (downhole compression apparatus) for implementing the method is currently underway.

Since the bottom portion of the gas well has a severe environmental condition, the downhole compression apparatus is required to have high environment-resistant performance. Especially, since a motor used for the downhole compression apparatus has a relatively low heat-resistant temperature, a technology to appropriately cool the motor is essential to realize the downhole compression apparatus, which is operated on the bottom portion of the gas well with a high environmental temperature. Compression apparatuses including means for cooling a motor are described in PTL 1 and PTL 2, for example.

PTL 1 discloses, regarding a compression apparatus used in a gas well, a configuration to cool a compressed gas by heat exchange with an outside, and brings a part of the cooled compressed gas in contact with a motor, thereby to cool the motor. Meanwhile, PTL 2 discloses, regarding a compression apparatus for underwater operation, a configuration to cool a motor, using a coolant circulating inside and outside the compression apparatus.

CITATION LIST

Patent Literatures

PTL 1: JP 2012-013072 A

PTL 2: JP 2009-530537 W

SUMMARY OF INVENTION

Technical Problem

Both of the systems of cooling a motor disclosed in PTL and PTL 2 use heat exchange with an outside, and can appropriately decrease the temperature of the motor if the systems are applied to a compression apparatus operated on a ground with a low environmental temperature or underwater.

However, for example, in a case of a downhole compression apparatus that is operated deep in the ground, the environmental temperature is high, and the cooling system that uses heat exchange with an outside may not be able to appropriately cool the motor.

The present invention has been made in view of the above problems, and an objective is to provide a compression apparatus that can appropriately cool a motor even in a high-temperature operation environment.

To solve the above problems, the present invention includes: a first rotating shaft; a first compressor attached to the first rotating shaft, and adapted to compress an ambient gas to emit a high-pressure compressed gas; a first motor attached to an upstream side of the first compressor on the first rotating shaft, and adapted to drive the compressor; and expansion means provided at an upstream side of the compressor, and adapted to expand a part of the ambient gas to generate a low-temperature gas to be used to cool the first motor.

Advantageous Effects of Invention

According to the present invention, a motor of a compression apparatus can be appropriately cooled even in a high-temperature operation environment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of a gas well in which a compression apparatus according to a first embodiment of the present invention is installed.

FIG. 2 is a structural view of the compression apparatus according to the first embodiment of the present invention.

FIG. 3 is a TS diagram illustrating a state transition of a gas used for cooling of a motor of the compression apparatus according to the first embodiment of the present invention.

FIG. 4 is a structural view of a compression apparatus according to a second embodiment of the present invention.

FIG. 5 is a structural view of a compression apparatus according to a third embodiment of the present invention.

FIG. 6 is a structural view of a compression apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a structural view of a compression apparatus according to a fifth embodiment of the present invention.

FIG. 8 is a structural view of a compression apparatus according to a sixth embodiment of the present invention.

FIG. 9 is a structural view of a compression apparatus according to a seventh embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments for implementing the present invention will be described with reference to the drawings. Note that the same or equivalent portions are denoted with the same reference sign in the drawings, and overlapping description is appropriately omitted.

First Embodiment

FIG. 1 is a sectional view of a gas well in which a compression apparatus according to the present embodiment is installed. A gas well 1 is an excavated hole reaching a gas layer 2 from the ground, and a steel pipe 70 for protecting an inner wall is installed inside the gas well 1. A compression apparatus 10 is attached to an inner wall of the steel pipe 70 at a bottom portion of the gas well 1 with a support member (not illustrated). The compression apparatus 10 is connected with a power supply device 9 installed on the ground through a power transmission cable 8 provided in the steel pipe 70. A packer 71 is attached in a gap between the compression apparatus 10 and the inner wall of the steel pipe 70. The packer 71 separates a lower side (upstream side) and an upper side (downstream side) of the compression apparatus 10 and prevents a backflow of the gas from the downstream side to the upstream side of the compression apparatus 10. The compression apparatus 10 sucks natural gases (hereinafter, referred to as ambient gases) 80 and 82 in the gas layer 2 where the pressure is decreased to a level where the artesian flow is not possible, compresses the gas to an artesian pressure, and then emits the natural gas toward the ground. A compressed gas 83 emitted from the compression apparatus 10 rises in the steel pipe 70 and flows in an artesian manner to the ground, is sent to a separator 5 through a gas transport pipe 4, and is separated to a gas component and an oil component.

During the operation of the compression apparatus 10, about 10 to 20% of the power supplied to the compression apparatus 10 is converted into heat as a power loss of a motor 40 (see FIG. 2). Therefore, the compression apparatus 10 needs to appropriately remove the heat generated by the motor 40 and maintain the temperature of the motor 40 to be a predetermined temperature or less, in order to secure reliability of an insulating material of a coil (not illustrated) built in the motor 40, and in order to prevent demagnetization of a permanent magnet (not illustrated) built in the motor 40.

FIG. 2 is a structural view of the compression apparatus according to the present embodiment. The compression apparatus 10 includes a casing 11 that forms an outline of the compression apparatus, a rotating shaft 50 rotatably supported to an inner center of the casing 11 with bearings 60 and 61, and a main compressor 30, a sub compressor 31, the motor 40, and a turbine 20, which are attached in order from the downstream side of the rotating shaft 51. The casing 11 has different inner diameters in a portion that houses the main compressor 30 having a large outer diameter, and a portion that houses the turbine 20, the motor 40, and the sub compressor 31 having a small outer diameter. A step surface 11a is formed at the upstream side of the main compressor 30. A discharge port 14 through which the compressed gas 83 discharged from the main compressor 30 is emitted is formed in an upper end surface of the casing 11. A plurality of main suction ports 12 leading to a vicinity of an inlet of the main compressor 30 is formed in the step surface 11a of the casing 11. A sub suction port 13 leading to a vicinity of an inlet of the turbine 20 is formed in a lower end surface of the casing 11.

The ambient gas 80 sucked through the sub suction port 13 passes through the turbine 20 and is adiabatically expanded to become a low-pressure low-temperature gas (hereinafter, referred to as low-temperature gas) 81. The low-temperature gas 81 cools the motor 40 while passing around the motor. The low-temperature gas 81 used to cool the motor 40 is compressed to a pressure nearly equal to the ambient gas 82 in the sub compressor 31. The gas compressed in the sub compressor 31 is mixed with the ambient gas 82 sucked through the main suction port 12 and compressed to a predetermined pressure in the main compressor 30 to become the compressed gas 83, and is emitted toward the ground.

FIG. 3 is a TS diagram illustrating a state transition of the gas that cools the motor 40 of the compression apparatus 10. While an existing turbine or compressor cannot realize an isentropic process, processes of the turbine and the compressor are expressed in the isentropic process in FIG. 3, for simplification of the description and easy understanding of the operation. In FIG. 3, a point 111 indicates a state of the ambient gas 80 sucked through the sub suction port 13. The ambient gas 80 in the state of the point 111 is adiabatically expanded in the turbine 20 and is decreased in the temperature and the pressure, thereby to become the low-temperature gas 81, and reaches a state indicated by a point 112. The low-temperature gas 81 absorbs the heat of the motor 40 at constant pressure, thereby to be increased in the temperature, and reaches a state indicated by a point 113. The low-temperature gas 81 used to cool the motor 40 is adiabatically compressed in the sub compressor 31, thereby to be increased in the temperature, and reaches a state of a point 114. Next, the low-temperature gas 81 is mixed with the ambient gas 82 sucked through the main suction port 12, thereby to be decreased in the temperature, and reaches a state of a point 115. Finally, the gas is adiabatically compressed in the main compressor 30, and is increased in the temperature and the pressure, thereby to become the compressed gas 83, and is emitted to an outside through the discharge port 14 in a state illustrated by a point 116. As described above, the thermal energy absorbed from the motor 40 is transported to the ground while being maintained as the internal energy of the gas without being leaked to an outside with a radiator and the like. Therefore, the state transition of the gas used to cool the motor 40 does not form a closed cooling cycle.

According to the present embodiment configured as described above, the ambient gas 80 sucked through the sub suction port 13 is adiabatically expanded in the turbine 20 and converted into the low-temperature gas 81, and the low-temperature gas 81 is brought to circulate around the motor 40, so that the motor 40 can be maintained to a lower temperature than an ambient environment. As a result, reliability of the insulating material of the motor 40 can be secured, or a cheaper insulating material can be used. Further, the heat absorbed from the motor 40 is discharged as internal energy of the compressed gas 83, so that it is not necessary to provide a radiating fin and the like for cooling the motor 40 on an outside surface of the casing 11, and downsizing of the compression apparatus 10 becomes possible.

Note that, in the compression apparatus 10 according to the present embodiment, the motor 40 drives the sub compressor 31, in addition to the main compressor 30. Therefore, the power consumption of the motor 40 is increased, compared with a configuration of driving the main compressor 30 only. However, the energy collected in the turbine 20 when the ambient gas 80 is adiabatically expanded is used to drive the sub compressor 31, so that the power necessary to drive the sub compressor 31 can be suppressed.

Further, a heat loss of the motor 40 is about 10 to 20% of supplied power. Therefore, the amount of gas necessary to remove the heat does not need the total amount of the ambient gases 80 and 82 sucked by the compression apparatus 10. In the compression apparatus 10 in the present embodiment, only a part of the ambient gases 80 and 82 (the ambient gas 80 sucked through the sub suction port 13) is adiabatically expanded and is used for cooling. Therefore, the capacity of the turbine 20 and the sub compressor 31 can be suppressed to about the several part of the main compressor 30, compared with the case where the total amount is expanded, and the power necessary to generate the low-temperature gas 81 can be suppressed.

Further, the low-temperature gas 81 used for cooling is compressed to a pressure nearly equal to the ambient gas 82 in the sub compressor 31, so that the pressure near the inlet of the main compressor 30 can be maintained constant, and a decrease in compression efficiency due to the main compressor 30 can be prevented.

Second Embodiment

FIG. 4 is a structural view of a compression apparatus according to a second embodiment of the present invention. Hereinafter, different points of a compression apparatus 10A according to the present embodiment from the compression apparatus 10 (see FIG. 2) according to the first embodiment will be mainly described.

A sub compressor 31 of the compression apparatus 10A according to the present embodiment is attached to a hollow rotating shaft 52 at an immediate downstream position of a motor 40, the rotating shaft 52 being rotatably supported around a rotating shaft 50 with bearings 64 and 65. A motor 42 is attached at an immediate upstream position of the sub compressor 31 on the rotating shaft 52. Meanwhile, a turbine 20 is attached to a hollow rotating shaft 51 at an immediate upstream position of the motor 40, the rotating shaft 51 being rotatably supported around the rotating shaft 50 with bearings 62 and 63. A generator 41 is attached at an immediate downstream position of the turbine 20 on the rotating shaft 51.

The sub compressor 31 is driven by the motor 42, and the generator 41 is driven by power collected in the turbine 20. The power generated in the generator 41 is supplied to the motor 42, as needed, and is used to drive the sub compressor 31.

The present embodiment configured as described above can also achieve similar effects to the first embodiment. Further, the turbine 20, the sub compressor 31, and a main compressor are rotated in a non-synchronized manner, whereby the compression apparatus 10A can flexibly support change of an environmental condition such as the pressure of an ambient gas 80 or the pressure of a compressed gas 83, and a wide range of operation conditions including a condition of at the time of startup.

Third Embodiment

FIG. 5 is a structural view of a compression apparatus according to a third embodiment of the present invention. Hereinafter, different points of a compression apparatus 10B according to the present embodiment from the compression apparatus 10 (see FIG. 2) according to the first embodiment will be mainly described.

A power transmission cable 8 of the compression apparatus 10B according to the present embodiment passes through a cable protection pipe 94 and is arranged in a steel pipe 70. The cable protection pipe 94 is configured from a heat insulating member, and prevents intrusion of heat from a high-temperature compressed gas 83 into the cable protection pipe 94. A heat exchanger 90 is provided near an inner wall of the steel pipe 70 and outside a casing 11. One end of one passage 90a of the heat exchanger 90 communicates into a vicinity of an outlet of a turbine 20 in the casing 11 through a gas transport pipe 91, and the other end of the passage 90a communicates into a vicinity of an inlet of a sub compressor 31 in the casing 11 through a gas transport pipe 92. One end of the other passage 90b of the heat exchanger 90 communicates into a vicinity of an outlet of a main compressor 30 in the casing 11 through a gas transport pipe 93, and the other end of the passage 90b communicates into the cable protection pipe 94.

A part of a low-temperature gas 81 is guided from the vicinity of the outlet of the turbine 20 to the heat exchanger 90 through the gas transport pipe 91, exchanges heat with apart of the compressed gas 83 guided through the gas transport pipe 93, is then guided to the vicinity of the inlet of the sub compressor 31 through the gas transport pipe 92, and is joined with the low-temperature gas 81 used to cool a motor 40. Meanwhile, a part of the compressed gas 83 guided through the gas transport pipe 93 becomes a low-temperature compressed gas (hereinafter, referred to as low-temperature compressed gas) 84 by heat exchange with a part of the low-temperature gas 81 guided through the gas transport pipe 91, and flows into the cable protection pipe 94. A low-temperature compressed gas 84 rises in the cable protection pipe 94 while cooling the power transmission cable 8, and is joined with the compressed gas 83 on the ground. Here, a configuration to cause a part of the low-temperature gas 81 to flow into the cable protection pipe can be considered. However, the pressure of the low-temperature gas 81 is less than an artesian pressure, and the low-temperature gas 81 flowing into the cable protection pipe 94 cannot reach the ground. Therefore, the configuration to cause a part of the low-temperature gas 81 to flow into the cable protection pipe 94 is difficult to cool the entire power transmission cable 8.

The present embodiment configured as described above can also achieve similar effects to the first embodiment. Further, the power transmission cable 8 is arranged in the cable protection pipe 94 having a heat insulation property, and a part of the compressed gas 83 is converted into the low-temperature compressed gas 84 by the heat exchange with a part of the low-temperature gas 81, and is sent to the ground through the cable protection pipe 94, whereby the power transmission cable 8 can be protected from the heat of the compressed gas 83.

Fourth Embodiment

FIG. 6 is a structural view of a compression apparatus according to a fourth embodiment of the present invention. Hereinafter, different points of a compression apparatus 10C according to the present embodiment from the compression apparatus 10 (see FIG. 2) according to the first embodiment will be mainly described.

A motor 40 of the compression apparatus 10C according to the present embodiment is attached at an immediate upstream position of a turbine 20 on a rotating shaft 50, and a sub suction port 13 is formed near an inlet of the turbine 20 in a side surface of a casing 11. One end of a heat transport pipe 100 is wound around an outer periphery of the motor 40, and the other end of the heat transport pipe 100 is connected to a radiator 101 arranged between the turbine 20 and a sub compressor 31. Heat generated in the motor 40 is transported to the radiator 101 through the heat transport pipe 100, and is emitted into a low-temperature gas 81 by the radiator 101. As the heat transport pipe, a device such as a heat pipe or a thermosiphon, to which phase change of a coolant is applied, is favorable.

The present embodiment configured as described above can also achieve similar effects to the first embodiment. Further, the motor 40 is arranged at an upstream side of the turbine 20 further separated from a main compressor 30 that becomes a high temperature, instead of at a downstream side of the turbine 20, whereby an increase in the temperature of the motor 40 can be suppressed.

Fifth Embodiment

FIG. 7 is a structural view of a compression apparatus according to a fifth embodiment of the present invention. Hereinafter, different points of a compression apparatus 10D according to the present embodiment from the compression apparatus 10 (see FIG. 2) according to the first embodiment will be mainly described.

A motor 40 of the compression apparatus 10D according to the present embodiment is attached at an immediate upstream position of a main compressor 30 on a rotating shaft 50, and a turbine 20 and a sub compressor 31 are attached to a hollow rotating shaft 51 at an immediate upstream position of the motor 40, the rotating shaft 51 being rotatably supported around a rotating shaft 50 with bearings 62 and 63. A motor 42 is attached at an immediate downstream position of the sub compressor 31 on the rotating shaft 51. The turbine 20 and the sub compressor 31 are partitioned to the upstream side and to the downstream side with a partition 15. A gas transport pipe 95 is attached to outer peripheral portions of the motors 40 and 42, and both ends of the gas transport pipe 95 are open to a vicinity of an outlet of the turbine 20 at the upstream side of the partition 15, and to a vicinity of an inlet of the sub compressor 31 at the downstream side of the partition 15.

The turbine 20 and the sub compressor 31 are driven by the motor 42. A low-temperature gas 81 discharged from the turbine 20 flows into the gas transport pipe 95 and is used to cool the motors 40 and 42, and is then guided to the vicinity of the inlet of the sub compressor 31.

The present embodiment configured as described above can also achieve similar effects to the first embodiment. Further, the turbine 20 and the sub compressor 31 are rotated in non-synchronization with the main compressor 30, whereby the compression apparatus 10D can support a wide range of operation conditions. Note that the motor 40 and the motor 42 may be installed at an upstream side of the turbine 20. In that case, a heat transport pipe 100 (see FIG. 6) to which the phase change of a coolant is applied, which has been described in the fourth embodiment, can be used in place of the gas transport pipe 95.

Sixth Embodiment

FIG. 8 is a structural view of a compression apparatus according to a sixth embodiment of the present invention. Hereinafter, different points of a compression apparatus 10E according to the present embodiment from the compression apparatus 10 (see FIG. 2) according to the first embodiment will be mainly described.

The compression apparatus 10E according to the present embodiment includes an expansion valve 21 in place of a turbine 20 (see FIG. 2). An ambient gas 80 sucked through a sub suction port 13 passes through the expansion valve 21 and is adiabatically expanded, thereby to become a low-temperature gas 81.

The present embodiment configured as described above can also obtain similar effects to the first embodiment. Further, the turbine is not included. Therefore, the structure of the compression apparatus 10E is simplified.

Seventh Embodiment

FIG. 9 is a structural view of a compression apparatus according to a seventh embodiment of the present invention. Hereinafter, different points of a compression apparatus 10F according to the present embodiment from the compression apparatus 10 (see FIG. 2) according to the first embodiment will be mainly described.

The compression apparatus 10F according to the present embodiment does not include a sub compressor 31 (see FIG. 2), and a turbine 20 is attached to a rotating shaft 53 at an upstream side of a rotating shaft 50, the rotating shaft 53 being supported with bearings 64 and 65 independently of the rotating shaft 50. A generator 41 is attached at an immediate downstream position of the turbine 20 on the rotating shaft 53. The generator 41 is connected through a cable 120 to a heater 121 arranged outside a casing 11.

When a main compressor 30 is driven by a motor 40, the downstream side of the turbine 20 becomes low pressure, and an ambient gas 80 sucked through a sub suction port 13 passes through the turbine 20 and is adiabatically expanded, thereby to become a low-temperature gas 81. The low-temperature gas 81 cools the motor 40 while passing around the motor 40. The low-temperature gas 81 used to cool the motor 40 is mixed with an ambient gas 82 sucked through a main suction port 12, and compressed in the main compressor 30 to become a compressed gas 83, and is emitted through a discharge port 14. Energy collected in the turbine 20 is converted into power by the generator 41, and is further converted into heat in the heater 121. The heat generated in the heater 121 is radiated into the compressed gas 83, and is sent to the ground together with the compressed gas 83.

The present embodiment configured as described above can also obtain similar effects to the first embodiment. Further, the sub compressor is not included. Therefore, the structure of the compression apparatus 10F is simplified. Further, the turbine 20 is attached to the rotating shaft 53 dependent of the rotating shaft 50. Therefore, control to bring the main compressor 30 and the turbine 20 to be in cooperation with each other becomes unnecessary at the time of startup. Therefore, the control of the compression apparatus 10 can be simplified. Note that, in FIG. 9, the heater 121 is arranged at the downstream side of the compression apparatus 10. However, the heater 121 can be arranged at an upstream side.

Note that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail to easily describe the present invention, and the present invention is not necessarily limited to one including all the described configurations. Further, a part of configurations of a certain embodiment can be replaced with a configuration of another embodiment. Further, a configuration of another embodiment can be added to a configuration of a certain embodiment. Further, another configuration can be added to/deleted from/replaced with a part of a configuration of each embodiment.

REFERENCE SIGNS LIST

10, 10A, 10B, 10C, 10D, 10E, and 10F compression apparatus

20 turbine (expansion means)

21 Expansion valve (expansion means)

30 main compressor (first compressor)

31 sub compressor (second compressor)

40 and 42 motor

41 generator

50 rotating shaft (first rotating shaft)

51 and 53 rotating shaft (second rotating shaft)

80 and 82 ambient gas

81 low-temperature gas

83 compressed gas

84 low-temperature compressed gas

90 heat exchanger

94 cable protection pipe

100 heat transport pipe

101 radiator

Claims

1. A compression apparatus comprising:

a first rotating shaft;

a first compressor attached to the first rotating shaft, and adapted to compress an ambient gas to emit a high-pressure compressed gas;

a first motor attached to an upstream side of the first compressor on the first rotating shaft, and adapted to drive the compressor; and

expansion means provided at an upstream side of the compressor, and adapted to expand a part of the ambient gas to generate a low-temperature gas to be used to cool the first motor.

2. The compression apparatus according to claim 1, further comprising:

a second compressor provided at the upstream side of the first compressor and at a downstream side of the expansion means, and adapted to compress the low-temperature gas used to cool the first motor to a pressure equal to the ambient gas, wherein

the first compressor mixes and compresses the low-temperature gas compressed by the second compressor, and a part of the remaining ambient gas to generate the compressed gas.

3. The compression apparatus according to claim 1, wherein the expansion means is a turbine.

4. The compression apparatus according to claim 2, wherein the turbine is attached to the first rotating shaft, and is driven by the first motor.

5. The compression apparatus according to claim 2, further comprising:

a second rotating shaft provided independently of the first rotating shaft; and

a second motor attached to the second rotating shaft, wherein

the turbine is attached to the second rotating shaft, and driven by the second motor, and

the expansion means expands a part of the ambient gas to generate the low-temperature gas to be used to cool the first motor and the second motor.

6. The compression apparatus according to claims 1 to 5 claim 1,

the compression apparatus being a downhole compression apparatus installed in a gas well, and

the compression apparatus further comprising:

a power supply device arranged on a ground;

a power transmission cable that connects the power supply device and the downhole compression apparatus;

a cable protection pipe inserted into the power transmission cable; and

a heat exchanger provided between the cable protection pipe and the downhole compression apparatus, and adapted to convert a part of the compressed gas into a low-temperature compressed gas by exchanging heat with a part of the low-temperature gas, and to cause the low-temperature compressed gas to flow into the cable protection pipe.

7. The compression apparatus according to claim 1, further comprising:

a radiator installed on a downstream side of the expansion means; and

a heat transport pipe that connects the first motor and the radiator.

8. The compression apparatus according to claim 1, wherein the expansion means is an expansion valve.