A direct-drive two-stage supercritical carbon dioxide compressor

Abstract

The present invention discloses a direct-driven two-stage supercritical carbon dioxide compressor, which has the advantages of compact structure, high efficiency and low noise. A direct-driven two-stage supercritical carbon dioxide compressor, characterized in that: the high-speed motor includes a motor housing and a stator, a rotor and an air bearing system arranged in the motor housing, a primary compressor and a secondary compressor are respectively arranged at both ends of the high-speed motor, the impellers of the primary compressor and the secondary compressor are both installed on the rotor of the high-speed motor, the primary compressor and the secondary compressor are connected in series to form a compression system, the air inlet of the primary compressor serves as the air inlet of the compression system, and the air outlet of the secondary compressor serves as the air outlet of the compression system.

Description

Technical Field

[0001] The invention relates to the technical field of supercritical carbon dioxide power generation systems, and in particular to a direct-driven two-stage supercritical carbon dioxide compressor. Background Art

[0002] Since the first industrial revolution, the main way to use thermal energy is to convert thermal energy into mechanical energy through a power system to provide power for human activities. The supercritical carbon dioxide power generation system is a type of power system. It uses supercritical carbon dioxide as a working fluid to convert the heat of the heat source into mechanical energy. The heat source can come from nuclear reactors, solar energy, geothermal energy, industrial waste heat, chemical dye combustion, etc. The excellent properties of supercritical carbon dioxide working fluid make its system have good application prospects and research value. Since carbon dioxide can only become supercritical when the temperature reaches 31.1℃ and the pressure reaches 7.38Mpa. Therefore, in the current supercritical carbon dioxide power generation system, the compressor is a key component in the entire system. The efficiency of the compressor has a great impact on the efficiency of the entire system. It integrates high-speed permanent magnet motors, gas bearings, two-stage impeller coaxial installation and other high technologies. Due to the high speed, the compressor has a high power density, and the volume is much smaller than that of ordinary compressors of the same power, which can effectively save materials. In addition, it is connected to the prime mover, cancels the traditional speed increase mechanism, has high transmission efficiency and low noise. However, a series of shaft system dynamics and bearing problems caused by high-speed rotating machinery, as well as sealing problems caused by high-pressure working conditions, restrict the development of supercritical carbon dioxide compressors. Summary of the invention

[0003] The object of the present invention is to overcome the deficiencies of the prior art and to provide a direct-drive two-stage supercritical carbon dioxide compressor having the advantages of compact structure, high efficiency and low noise.

[0004] The object of the present invention is achieved in that:

[0005] A direct-drive two-stage supercritical carbon dioxide compressor, characterized in that: the high-speed motor includes a motor housing and a stator, a rotor, and an air bearing system arranged in the motor housing; a primary compressor and a secondary compressor are respectively arranged at both ends of the high-speed motor; the impellers of the primary compressor and the secondary compressor are both installed on the rotor of the high-speed motor; the primary compressor and the secondary compressor are connected in series to form a compression system; the air inlet of the primary compressor serves as the air inlet of the compression system, and the air outlet of the secondary compressor serves as the air outlet of the compression system.

[0006] Preferably, the air bearing system uses supercritical carbon dioxide as a lubricating medium, and the motor housing is provided with a bearing air inlet hole and a bearing exhaust hole. The bearing air inlet hole is used to introduce supercritical carbon dioxide into the air bearing system; and the bearing exhaust hole is used to discharge supercritical carbon dioxide.

[0007] Preferably, the bearing air inlet is connected to the air outlet of the secondary compressor, so as to introduce supercritical carbon dioxide into the air bearing system to lubricate the air bearing system, and the bearing exhaust hole is connected to the air inlet of the primary compressor, so as to introduce the supercritical carbon dioxide discharged from the air bearing system into the compression system.

[0008] Preferably, an air storage tank and a pressure control valve are connected in series between the air outlet of the secondary compressor and the air inlet of the bearing, the air storage tank is used to store supercritical carbon dioxide, and the pressure control valve is used to control the pressure of the supercritical carbon dioxide introduced into the air bearing system.

[0009] Preferably, a suction pump is connected between the bearing exhaust hole and the air inlet of the first-stage compressor to introduce the supercritical carbon dioxide discharged from the air bearing system into the compression system.

[0010] Preferably, the stator includes a stator core and a stator coil, a stator cooling channel is arranged in the stator core, a stator cooling air inlet and a stator cooling air outlet are arranged on the motor housing, the stator cooling air inlet and the stator cooling air outlet are communicated with the stator cooling channel, the stator cooling air inlet is connected to the air outlet of the secondary compressor, and is used to introduce supercritical carbon dioxide into the stator cooling channel to cool the stator; the stator cooling air outlet is connected to the air inlet of the primary compressor, and is used to merge the supercritical carbon dioxide in the stator cooling channel into the compression system.

[0011] Preferably, a dry gas sealing device is provided between the motor housing and the housing of the first-stage compressor and the housing of the second-stage compressor respectively;

[0012] The dry gas sealing device comprises a cylindrical installation shell, the two ends of which are respectively fixedly connected to the motor housing and the shell of the first-stage compressor / the shell of the second-stage compressor, a cylindrical dry gas sealing pressure-bearing shell is arranged in the installation shell, the part of the rotor of the high-speed motor corresponding to the dry gas sealing pressure-bearing shell is a stepped shaft, a T-shaped shaft sleeve is sleeved on the small-diameter section of the stepped shaft, a dry gas sealing dynamic ring and a dry gas sealing static ring are sleeved between the small-diameter section of the shaft sleeve and the dry gas sealing pressure-bearing shell, the dry gas sealing dynamic ring is fixed to the shaft sleeve, the dry gas sealing static ring is fixed to the dry gas sealing pressure-bearing shell, a high-pressure end comb teeth seal is arranged between the large-diameter section of the shaft sleeve and the dry gas sealing pressure-bearing shell, and a low-pressure end comb teeth seal is arranged between the large-diameter section of the stepped shaft and the dry gas sealing pressure-bearing shell;

[0013] The installation shell is provided with a sealed air inlet, a sealed air exhaust port, and a balanced air inlet. The sealed air inlet, the sealed air exhaust port, and the balanced air inlet are connected to the pressure control system and the air outlet of the secondary compressor in sequence. The sealed air inlet is used to introduce supercritical carbon dioxide from the air outlet of the secondary compressor. The dry gas seal pressure shell is provided with a first through hole for reintroducing the supercritical carbon dioxide introduced by the sealed air inlet into the high-pressure end comb tooth seal and between the dry gas seal dynamic ring and the dry gas seal static ring. The sealed air exhaust port is used to discharge the supercritical carbon dioxide that passes through the gap between the dry gas seal dynamic ring and the dry gas seal static ring, the gap between the dry gas seal pressure shell and the small diameter section of the stepped shaft, and the gap between the dry gas seal pressure shell and the low-pressure end comb tooth seal in sequence. The low-pressure end comb tooth seal is provided with a second through hole for introducing the supercritical carbon dioxide from the balanced air inlet into the middle balanced air pressure of the low-pressure end comb tooth seal.

[0014] Preferably, the air bearing system includes a pure radial bearing, a radial-thrust combined bearing and a pure thrust bearing; the pure radial bearing is located at one end of the rotor, the radial-thrust combined bearing and the pure thrust bearing are located at the other end of the rotor, and the pure thrust bearing is located on the inner side of the radial-thrust combined bearing.

[0015] Preferably, the first-stage compressor and the second-stage compressor each have a diffuser, and the diffuser is located between the air inlet and the compressor impeller of the compressor.

[0016] Preferably, the compressor impeller is circumferentially fixed to the end of the rotor by involute teeth arranged in the axial hole, and is tightened and fixed by a torque transmission rod and a locking nut.

[0017] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0018] The compressor structure proposed by the present invention has a motor, a compressor impeller and a sealing structure coaxially connected, which eliminates the traditional method of connecting the gear box and the motor through a coupling. It has the advantages of compact and simple structure and high power density. The bearing gas exhaust is introduced into the air inlet airflow of the compressor to achieve zero leakage. At the same time, the compressor of the present invention has no oil or air in the entire experimental prototype, and is suitable for the compression of micro-supercritical carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the overall structure diagram of the present invention;

[0020] Figure 2 This is a structural diagram of the dry gas seal of the present invention;

[0021] Figure 3 This is a structural diagram of the impeller installation of the present invention;

[0022] Figure 4This is a schematic diagram of the involute teeth of the impeller of the present invention;

[0023] Figure 5 It is the flow path diagram of the supercritical carbon dioxide of the present invention. DETAILED DESCRIPTION

[0024] join Figure 1-Figure 5 A direct-drive two-stage supercritical carbon dioxide compressor includes a first-stage compressor, a second-stage compressor, a dry gas sealing device and a high-speed motor. The air bearing system of the high-speed motor uses supercritical carbon dioxide as a lubricating medium.

[0025] A primary compressor 11a and a secondary compressor 11b are installed at both ends of the high-speed motor respectively. Supercritical carbon dioxide enters from the air inlet of the primary compressor, and the high-speed motor drives the primary compressor impeller 12a to compress the supercritical carbon dioxide to do work. The supercritical carbon dioxide then enters the air inlet of the secondary compressor 11b from the air outlet of the primary compressor 11a, and is compressed again by the secondary compressor impeller 12b to do work.

[0026] The motor housing 35 is provided with a bearing air inlet hole for introducing supercritical carbon dioxide into the bearing system from the outside of the housing; the motor housing is provided with a bearing exhaust hole for exhausting supercritical carbon dioxide discharged from the bearing system out of the housing.

[0027] The bearing air inlet is connected to the air outlet of the secondary compressor, and is used to divert part of the supercritical carbon dioxide from the supercritical carbon dioxide gas flow at the compressor outlet and pass it into the bearing 31; the bearing exhaust hole is connected to the air inlet of the first-stage compressor, and is used to merge the supercritical carbon dioxide discharged from the bearing system into the air inlet air of the first-stage compressor.

[0028] An air storage tank and a pressure control valve are arranged between the compressor outlet and the bearing air inlet; the air storage tank inlet is connected to the compressor outlet, and is used to store part of the supercritical carbon dioxide diverted from the supercritical carbon dioxide gas flow at the compressor outlet; the pressure control valve is connected between the air storage tank outlet and the bearing air inlet, and is used to control the pressure of the supercritical carbon dioxide entering the bearing; a suction pump is arranged between the bearing exhaust hole and the compressor air inlet, and is used to merge the supercritical carbon dioxide discharged from the bearing into the compressor air inlet air flow.

[0029] The stator 32 includes a stator core and a stator coil, a stator cooling channel is provided in the stator core, and the motor housing is provided with a stator cooling air inlet and a stator cooling air outlet which are connected from the stator cooling channel to the outside of the motor housing; the stator cooling air inlet is connected to the compressor inlet, and is used to introduce the low-temperature supercritical carbon dioxide at the compressor inlet into the stator cooling channel to cool the stator; the stator cooling air outlet is connected to the compressor inlet, and is used to introduce the supercritical carbon dioxide in the stator cooling channel back to the compressor inlet.

[0030] The compressor head stage 11a and the compressor head stage 11b respectively include a first-stage diffuser 13a and a second-stage diffuser 13b. The supercritical carbon dioxide working medium first enters from the air inlet of the first-stage compressor head 11a and is introduced into the compressor impeller 12a through the first-stage diffuser 13a to compress the supercritical carbon dioxide and perform work. The compressed supercritical carbon dioxide is introduced from the air outlet of the first-stage compressor 11a into the air inlet of the second-stage compressor 11b, and then introduced into the second-stage compressor impeller 12b through the diffuser 13b of the second-stage compressor to compress the supercritical carbon dioxide and perform work.

[0031] The rotor includes a permanent magnet shaft 36, a dry gas sealing sleeve 38, a dry gas sealing dynamic ring 37, and the first-stage compressor impeller 12a and the second-stage compressor impeller 12b are respectively fixed to the two ends of the shaft 36 by means of involute teeth 16, a torsion rod 14 and a locking nut 15 for tightening.

[0032] A dry gas seal is arranged between the motor and the compressor, which includes a dry gas seal mounting housing 25, a dry gas seal pressure housing 26, a high-pressure end comb tooth seal 28, a shaft sleeve 38, a dry gas seal dynamic ring 37, a dry gas seal static ring 27, and a low-pressure end comb tooth seal 24. Supercritical carbon dioxide gas is led out from the compressor outlet and enters the main seal air inlet 21 through the pressure control system, and is then discharged from the seal gas exhaust port 22 and introduced into the compressor air inlet. The dry gas seal balance gas enters from the balance gas air inlet 23. A high-pressure end comb tooth seal 28 and a low-pressure end comb tooth seal 24 are also provided at both ends of the seal.

[0033] The air bearing system includes a pure radial bearing 31, a radial-thrust combined bearing 34 and a pure thrust bearing 33; the pure radial bearing 31 is sleeved between the motor housing 35 and the permanent magnet shaft 36, and the radial-thrust combined bearing 34 and the pure thrust bearing 33 are connected to the other end of the permanent magnet shaft and sleeved between the motor housing 35 and the permanent magnet shaft 36.

[0034] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A direct-drive two-stage supercritical carbon dioxide compressor, characterized in that: The high-speed motor includes a motor housing and a stator, a rotor, and an air bearing system arranged in the motor housing. A primary compressor and a secondary compressor are respectively arranged at both ends of the high-speed motor. The compressor impellers of the primary compressor and the secondary compressor are both installed on the rotor of the high-speed motor. The primary compressor and the secondary compressor are connected in series to form a compression system. The air inlet of the primary compressor serves as the air inlet of the compression system, and the air outlet of the secondary compressor serves as the air outlet of the compression system. The air bearing system uses supercritical carbon dioxide as a lubricating medium, and the motor housing is provided with a bearing air inlet hole and a bearing exhaust hole. The bearing air inlet hole is used to introduce supercritical carbon dioxide into the air bearing system; and the bearing exhaust hole is used to discharge supercritical carbon dioxide. The bearing air inlet is connected to the air outlet of the secondary compressor, and is used to introduce supercritical carbon dioxide into the air bearing system to lubricate the air bearing system. The bearing exhaust is connected to the air inlet of the primary compressor, and is used to introduce supercritical carbon dioxide discharged from the air bearing system into the compression system. An air storage tank and a pressure control valve are connected in series between the air outlet of the secondary compressor and the air inlet of the bearing, wherein the air storage tank is used to store supercritical carbon dioxide, and the pressure control valve is used to control the pressure of the supercritical carbon dioxide introduced into the air bearing system; A suction pump is connected between the bearing exhaust hole and the air inlet of the first-stage compressor to collect the low-pressure supercritical carbon dioxide discharged from the air bearing system into the compression system; The stator includes a stator core and a stator coil, a stator cooling channel is arranged in the stator core, a stator cooling air inlet and a stator cooling air outlet are arranged on the motor housing, the stator cooling air inlet and the stator cooling air outlet are communicated with the stator cooling channel, the stator cooling air inlet is connected to the air outlet of the secondary compressor, and is used to introduce supercritical carbon dioxide into the stator cooling channel to cool the stator; the stator cooling air outlet is connected to the air inlet of the primary compressor, and is used to merge the supercritical carbon dioxide in the stator cooling channel into the compression system.

2. A direct-drive two-stage supercritical carbon dioxide compressor according to claim 1, characterized in that: A dry gas sealing device is respectively arranged between the motor housing and the housing of the first-stage compressor and the housing of the second-stage compressor; The dry gas sealing device comprises a cylindrical installation shell, the two ends of which are respectively fixedly connected to the motor housing and the shell of the first-stage compressor / the shell of the second-stage compressor, a cylindrical dry gas sealing pressure-bearing shell is arranged in the installation shell, the part of the rotor of the high-speed motor corresponding to the dry gas sealing pressure-bearing shell is a stepped shaft, a T-shaped shaft sleeve is sleeved on the small-diameter section of the stepped shaft, a dry gas sealing dynamic ring and a dry gas sealing static ring are sleeved between the small-diameter section of the shaft sleeve and the dry gas sealing pressure-bearing shell, the dry gas sealing dynamic ring is fixed to the shaft sleeve, the dry gas sealing static ring is fixed to the dry gas sealing pressure-bearing shell, a high-pressure end comb teeth seal is arranged between the large-diameter section of the shaft sleeve and the dry gas sealing pressure-bearing shell, and a low-pressure end comb teeth seal is arranged between the large-diameter section of the stepped shaft and the dry gas sealing pressure-bearing shell; The installation shell is provided with a sealed air inlet, a sealed air exhaust port, and a balanced air inlet. The sealed air inlet, the sealed air exhaust port, and the balanced air inlet are connected to the pressure control system and the air outlet of the secondary compressor in sequence. The sealed air inlet is used to introduce supercritical carbon dioxide from the air outlet of the secondary compressor. The dry gas seal pressure shell is provided with a first through hole for reintroducing the supercritical carbon dioxide introduced through the sealed air inlet into the high-pressure end comb tooth seal and between the dry gas seal dynamic ring and the dry gas seal static ring. The sealed air exhaust port is used to discharge the supercritical carbon dioxide that passes through the gap between the dry gas seal dynamic ring and the dry gas seal static ring, the gap between the dry gas seal pressure shell and the small diameter section of the stepped shaft, and the gap between the dry gas seal pressure shell and the low-pressure end comb tooth seal in sequence. The low-pressure end comb tooth seal is provided with a second through hole for introducing the supercritical carbon dioxide from the isolation air inlet into the middle isolation atmosphere of the low-pressure end comb tooth seal.

3. The direct-drive two-stage supercritical carbon dioxide compressor according to claim 1, characterized in that: The air bearing system includes a pure radial bearing, a radial-thrust combined bearing and a pure thrust bearing; the pure radial bearing is located at one end of the rotor, the radial-thrust combined bearing and the pure thrust bearing are located at the other end of the rotor, and the pure thrust bearing is located on the inner side of the radial-thrust combined bearing.

4. A direct-drive two-stage supercritical carbon dioxide compressor according to claim 1, characterized in that: The first-stage compressor and the second-stage compressor each have a diffuser, and the diffuser is located between the air inlet and the compressor impeller of the compressor.

5. The direct-drive two-stage supercritical carbon dioxide compressor according to claim 1, characterized in that: The compressor impeller is circumferentially fixed to the end of the rotor through involute teeth arranged in the axial hole, and is tightened and fixed by the torsion transmission rod and the locking nut.

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