Centrifugal expansion machine

Abstract

The centrifugal expansion machine is characterized in that a flow guide cover is arranged between an impeller and a nozzle ring, the flow guide cover is arranged at a central opening of a base plate, and a barrel communicates with an outlet section; a containing space used for containing the static blades is formed between the flow guide cover and the nozzle ring, a plurality of movable blades which are sequentially and evenly distributed in the circumferential direction are arranged in the impeller, a movable blade medium channel is formed between every two adjacent movable blades, an annular fluid channel is formed between the nozzle ring and the impeller, and an annular diffusion channel is formed between the base plate and the nozzle ring. A medium inflow channel is defined by the inlet section, the flow guide cover and the nozzle ring. When the expansion machine works, a medium sequentially passes through the inlet section, the medium inflow channel, the annular fluid channel, the moving blade medium channel and the annular diffusion channel and then is discharged through the outlet section, and the expansion machine has the advantages of being high in expansion ratio, high in working capacity and capable of adapting to gas-liquid-solid multiphase media.

Description

Technical Field

[0001] The invention belongs to the technical field of turbine expanders and relates to a centrifugal expander. Background Art

[0002] Turbine expanders are core equipment in thermal cycle systems such as industrial waste heat and waste energy recovery and energy storage. They can achieve near-isentropic expansion of the working medium. Their conventional structural types include centripetal, axial flow and screw types. In recent years, with the continuous changes in application requirements, conventional structural expanders have been restricted in some special application areas. For example, in the process of recovering natural gas pressure at the wellhead, the medium pressure (tens of MPa) is not only higher than the adaptability range of conventional turbine expanders, but also the medium is a multiphase and multicomponent oil and gas mixture mixed with solid particles. The process is accompanied by complex gas-liquid two-phase flow, which makes the conventional structural expander induce structural vibration and cause erosion damage under the alternating change of fluid excitation force, affecting the performance and life of the unit; in the energy storage system, the expander inlet is often in a supercritical state, the medium specific volume changes greatly during the expansion process, and the expander outlet usually enters the deep two-phase zone, which means that a drastic gas-liquid phase change will occur inside the expander, so that the medium contains a large amount of liquid gas. The droplets in the conventional centrifugal expander will move radially outward under the action of centrifugal force, opposite to the mainstream flow direction, thereby causing wear and corrosion of the rotor structure. The above application requirements require the expander to meet the conditions of high expansion ratio, large stage enthalpy drop, pneumatic and geometric compatibility, and multiphase expansion. Compared with the centrifugal expander, the centrifugal expander can use centrifugal force to discharge impurities and droplets in the medium, which is particularly suitable for multiphase expansion applications.

[0003] However, the existing centrifugal expander structure of a single stage cannot adapt to high expansion ratio conditions. The currently disclosed expanders need to use multi-stage centrifugal or a combination of centrifugal and centripetal / axial flow types to adapt to high expansion ratio conditions.

[0004] For example, patent CN 109252900 B discloses "a compound turbine", which sequentially connects single-stage centrifugal-axial flow structures on the same main shaft, wherein the high-pressure section adopts a centrifugal turbine and the low-pressure section adopts an axial flow turbine. However, the volume flow rate of the axial flow turbine changes greatly during the expansion process, and the blade height changes significantly along the flow direction, forming a non-negligible velocity component along the blade height direction, which makes the cascade design difficult. Moreover, this centrifugal-axial flow combination makes the unit structure complex and the axial size significantly increased, which poses a challenge to the safe and stable operation of the equipment. Patents with similar combined structures include CN 104066937B "a method and turbine for expanding an organic working fluid in a Rankine cycle", which provides a multi-stage centrifugal-axial flow combined structure, and CN 202970801 U "a small combined steam turbine and multiple coaxial combined steam turbines", which provides a centrifugal-centripetal structure. Both have defects such as complex internal flow, large unit structure size, and high manufacturing cost. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a centrifugal expander having the characteristics of high expansion ratio, strong working capacity and adaptability to gas-liquid-solid multiphase media.

[0006] To achieve the above object, the present invention discloses a centrifugal expander, comprising a cylinder, a base plate, a cover plate and a plurality of stationary blades;

[0007] The cylinder is installed between the base plate and the cover plate, and an inlet section, a guide cover and a nozzle ring are arranged in the cylinder, wherein one end of the inlet section is connected to the air inlet of the cover plate, and the other end of the inlet section is connected to the central through hole of the nozzle ring, the guide cover is arranged between the impeller and the nozzle ring, the guide cover is arranged at the central opening of the base plate, and the cylinder is connected to the outlet section;

[0008] An accommodating space for accommodating stationary blades is formed between the guide cover and the nozzle ring, a plurality of moving blades are uniformly distributed in the circumferential direction in the impeller, a moving blade medium channel is formed between two adjacent moving blades, an annular fluid channel is formed between the nozzle ring and the impeller, and an annular pressure diffusion channel is formed between the base plate and the nozzle ring; a medium inflow channel is formed between the inlet section, the guide cover and the nozzle ring;

[0009] During operation, the medium passes through the inlet section, the medium inflow channel, the annular fluid channel, the moving blade medium channel and the annular diffuser channel in sequence and then is discharged through the outlet section.

[0010] Furthermore, each stationary blade is evenly distributed on the inner side surface of the nozzle ring along the circumferential direction with the axis of the nozzle ring as the center line.

[0011] Further, the center line of the impeller is aligned with the center line of the nozzle ring.

[0012] Furthermore, a main shaft is disposed through the middle of the impeller.

[0013] Furthermore, the main shaft is connected to a power device.

[0014] Furthermore, the flow area of ​​the medium inflow channel decreases uniformly along the medium flow direction.

[0015] Furthermore, the nozzle ring includes a stator disk, and each stator blade is arranged on the stator disk. The stator blade includes a bottom surface of the stator blade, a top surface of the stator blade, a pressure surface of the stator blade and a suction surface of the stator blade. The stator blade extends outward from the inner end surface of the stator disk and is connected to the inner end surface of the guide cover. The top surface of the stator blade is located directly above the bottom surface of the stator blade and the two have the same shape. A gap AC is formed between the pressure surface of the stator blade and the suction surface of the stator blade of adjacent stator blades.

[0016] Furthermore, the cross-sectional area of ​​the gap AC gradually decreases first and then increases along the medium flow direction.

[0017] Furthermore, the impeller includes a wheel cover ring, a moving wheel disc and a plurality of moving blades, the moving blades include a bottom surface of the moving blades, a top surface of the moving blades, a pressure surface of the moving blades and a suction surface of the moving blades, and the moving blades and the stationary blades have the same blade height, an axially extending boss is provided on the top surface of the moving blades, a hole matching the boss is provided on the wheel cover ring, and the top surface of the moving blade matches the wheel cover ring.

[0018] Furthermore, the cross-sectional area of ​​the medium passage of the moving blade first gradually increases and then gradually decreases along the medium flow direction.

[0019] The present invention has the following beneficial effects:

[0020] During the specific operation of the centrifugal expander described in the present invention, the medium passes through the inlet section, the medium inflow channel, the annular fluid channel, the moving blade medium channel and the annular pressure diffuser channel in sequence and then is discharged through the outlet section. Among them, the moving-static blades and the centrifugal structure that facilitates the movement of droplets and particles are adopted. The structure of axial inflow and radial outflow can use centrifugal force to separate the droplets and particles in the medium, which is suitable for the application of gas-liquid-solid multiphase medium. In addition, the pressure of the medium can be further converted into velocity energy after passing through the throat position of the medium inflow channel, and the medium is fully expanded in the medium inflow channel. Therefore, only a single-stage row of moving and static blades is needed to achieve a high expansion ratio, a large stage enthalpy drop, and a simple and compact structure of the whole machine. In addition, the present invention adopts a centrifugal impulse impeller, and the medium is fully expanded in the medium inflow channel and the gas-liquid phase change is completed at the same time, thereby avoiding large-scale gas-liquid phase change in the rotating parts, which is conducive to improving the stability of machine operation. The flow channel characteristics of first expansion and then contraction can effectively utilize the velocity energy of the medium, and the working capacity is strong and the whole machine efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 is a two-dimensional cross-sectional view of the present invention;

[0023] Figure 2 A three-dimensional exploded view of the present invention;

[0024] Figure 3 It is a schematic diagram of the structure of the air deflector 3;

[0025] Figure 4 is a cross-sectional view of the medium flowing into the channel 33;

[0026] Figure 5 The variation law of the flow cross-sectional area of ​​the medium flowing into the channel 33;

[0027] Figure 6 Schematic diagram of the nozzle structure;

[0028] Figure 7 is a partial view of a stationary blade 42;

[0029] Figure 8 is a schematic diagram of the structure of the impeller 5;

[0030] Fig. 9 It is a partial view of the moving blade 52 .

[0031] Among them, 1 is the main axis, 2 is the inlet section, 3 is the guide cover, 31 is the cone top surface, 32 is the cone bottom surface, 33 is the medium inflow channel, 4 is the nozzle ring, 41 is the static impeller, 42 is the static blade, 421 is the pressure surface of the static blade, 422 is the suction surface of the static blade, 423 is the blade top surface of the static blade, 424 is the static blade medium channel, 5 is the impeller, 51 is the wheel cover ring, 52 is the moving blade, 521 is the blade top surface of the moving blade, 522 is the pressure surface of the moving blade, 523 is the suction surface of the moving blade, 524 is the moving blade medium channel, 53 is the moving impeller, 6 is the outlet section, 7 is the base plate, 8 is the cylinder, 9 is the cover plate, 10 is the rotation direction, and 11 is the rotation axis. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0034] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0035] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0036] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0037] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0040] Embodiment 1

[0041] refer to Figure 1 The centrifugal expander described herein comprises a cylinder 8, a base plate 7, a cover plate 9 and a plurality of stationary blades 42; the cylinder 8 is installed between the base plate 7 and the cover plate 9, and an inlet section 2, a guide cover 3 and a nozzle ring 4 are arranged in the cylinder 8, wherein one end of the inlet section 2 is connected to the air inlet of the cover plate 9, and the other end of the inlet section 2 is connected to the central through hole of the nozzle ring 4, the guide cover 3 is arranged between the impeller 5 and the nozzle ring 4, and the guide cover 3 is arranged at the central opening of the base plate 7, and the cylinder 8 is connected with an outlet section 6; a hole for accommodating the stationary blades is formed between the guide cover 3 and the nozzle ring 4 The impeller 5 has a space for accommodating blades 42, and is provided with a plurality of moving blades 52 uniformly distributed in the circumferential direction. A moving blade medium channel 524 is formed between two adjacent moving blades 52, an annular fluid channel is formed between the nozzle ring 4 and the impeller 5, and an annular pressure diffuser channel is formed between the base plate 7 and the nozzle ring 4; a medium inflow channel 33 is formed between the inlet section 2, the guide cover 3 and the nozzle ring 4; when working, the medium passes through the inlet section 2, the medium inflow channel 33, the annular fluid channel, the moving blade medium channel 524 and the annular pressure diffuser channel in sequence and then is discharged through the outlet section 6.

[0042] Embodiment 2

[0043] refer to Figure 1 and Figure 2The centrifugal expander of the present invention comprises a main shaft 11, an inlet section 2, a guide cover 3, a nozzle ring 4, an impeller 5, an outlet section 6 and a volute, and the volute comprises a base plate 7, a cylinder 8 and a cover plate 9;

[0044] The cylinder 8 is installed between the base plate 7 and the cover plate 9, and an inlet section 2, a guide cover 3 and a nozzle ring 4 are arranged in the cylinder 8, wherein one end of the inlet section 2 is connected to the air inlet of the cover plate 9, and the other end of the inlet section 2 is connected to the central through hole of the nozzle ring 4, the guide cover 3 is arranged between the impeller 5 and the nozzle ring 4, and the guide cover 3 is arranged at the central opening of the base plate 7.

[0045] Specifically, the end of the inlet section 2 is connected to the air inlet on the cover plate 9 through bolts and an inlet flange, and the end of the inlet section 2 is connected to the nozzle ring 4 through bolts. A storage space for accommodating stationary blades 42 is formed between the air guide cover 3 and the nozzle ring 4. Each stationary blade 42 is evenly distributed on the inner side surface of the nozzle ring 4 along the circumferential direction with the axis of the nozzle ring 4 as the center line.

[0046] As an embodiment of the present invention, the center line of the impeller 5 is aligned with the center line of the nozzle ring 4, and a main shaft 1 is provided through the middle of the impeller 5. Specifically, one end of the main shaft 1 is connected to the impeller 5 through a shaft head nut, and the other end of the main shaft 1 is connected to a power device through a coupling or a gear sleeve. The power device can be a power-consuming device such as a generator, a compressor or a pump. A plurality of moving blades 52 are arranged in the impeller 5 and are evenly distributed in sequence along the circumferential direction. The gap between two adjacent moving blades 52 constitutes a moving blade medium channel 524. An annular fluid channel is formed between the nozzle ring 4 and the impeller 5, an annular pressure diffuser channel is formed between the base plate 7 and the nozzle ring 4, and an outlet section 6 is connected to the outer circumferential surface of the cylinder 8.

[0047] As an embodiment of the present invention, reference Figure 3 , Figure 4 and Figure 5 The cone top surface 31 and the cone bottom surface 32 of the guide cover 3 are smoothly transitioned by the optimal pneumatic / hydraulic profile. The inlet section 2, the guide cover 3 and the nozzle ring 4 form a medium inflow channel 33, and the flow area of ​​the medium inflow channel 33 is uniformly reduced along the medium flow direction, so that the fluid is steadily accelerated in the inlet section 2 of the medium inflow channel 33, and the medium flow direction is smoothly transitioned from the axial direction to the radial direction, providing a uniform incoming flow velocity distribution for the inlet of the stationary blade 42.

[0048] As an embodiment of the present invention, reference Figure 6 and Figure 7The nozzle ring 4 includes a stator disk 41, and each stator blade 42 is arranged on the stator disk 41. The stator blade 42 includes a bottom surface of the stator blade, a top surface 423 of the stator blade, a pressure surface 421 of the stator blade, and a suction surface 422 of the stator blade. The stator blade 42 extends outward from the inner end surface of the stator disk 41 and is connected to the inner end surface of the guide cover 3. The top surface 423 of the stator blade is located directly above the bottom surface of the stator blade and the two have the same shape. A gap AC is formed between the pressure surface 421 of the stator blade and the suction surface 422 of the stator blade of adjacent stator blades 42, wherein the cross-sectional area of ​​the AB section gradually decreases along the flow direction, and the pressure energy of the medium is quickly converted into kinetic energy. Through the flow channel design, the size of the throat B is reasonably controlled to meet the flow control targets such as subsonic / transonic speeds and adapt to different parameter conditions. The cross-sectional area of ​​the BC section gradually increases along the flow direction, and the pressure energy of the medium is further converted into kinetic energy. The flow rate continues to increase, and the pressure of the medium is close to the outlet pressure of the impeller 5.

[0049] As an embodiment of the present invention, reference Figure 8 and Fig. 9 The impeller 5 includes a wheel cover ring 51, a moving wheel disc 53 and a plurality of moving blades 52. The moving blades 52 include a bottom surface of the moving blade, a top surface 521 of the moving blade, a pressure surface 522 of the moving blade and a suction surface 523 of the moving blade, and the moving blades 52 have the same blade height as the stationary blades 42. An axially extending boss is provided on the top surface 521 of the moving blade, and a hole matching the boss is provided on the wheel cover ring 51. The top surface 521 of the moving blade matches the wheel cover ring 51 to form a closed impeller structure. The moving blade medium channel 524 between adjacent moving blades 52 is formed by the profile lines of the pressure surface 522 of the moving blade and the suction surface 521 of the moving blade, wherein the cross-sectional area of ​​the DE segment gradually increases along the flow direction, the kinetic energy of the medium is converted into pressure energy, and the relative velocity decreases, and the cross-sectional area of ​​the EF segment gradually decreases along the flow direction, the pressure energy of the medium is converted into velocity energy, and the relative velocity increases, and the relative velocity direction of the medium in the moving blade medium channel 524 changes greatly, from pointing to the pressure surface of the blade to pointing to the direction opposite to the rotation of the impeller 5.

[0050] The working principle of the present invention is:

[0051] a) The medium enters the centrifugal expander through the inlet section 2, and is evenly distributed to the inlet of the stationary blades 42 through the cavity formed by the inner end surface of the guide cover 3 and the inner end surface of the nozzle ring 4, and the flow direction is changed from axial to radial.

[0052] b) After the medium passes through the stationary blade medium channel 424, the pressure decreases and the flow rate increases. The enthalpy change generated in this process is equal to at least 95% of the total expansion of the medium in the centrifugal expander.

[0053] c) The high-speed medium flowing out of the nozzle ring 4 enters the moving blade medium channel 524 through the annular fluid channel formed between the outer circumference of the nozzle ring 4 and the outer circumference of the impeller 5. The high-speed medium impacts the pressure surface 522 of the moving blade and pushes the impeller 5 to rotate at high speed in the rotation direction 10. The pressure of the medium is further reduced after passing through the impeller 5.

[0054] d) The medium flowing out of the impeller 5 is decelerated and expanded in the annular expansion channel formed by the inner end surface of the base plate 7 and the inner end surface of the nozzle ring 4, and the residual speed of the medium flowing out of the impeller 5 is recovered, and the kinetic energy of the medium is converted into pressure energy.

[0055] e) After the medium flows out of the annular diffuser channel, the flow direction turns 90 degrees and enters the volute flow channel. The kinetic energy of the medium is further converted into pressure energy in the volute, and finally discharged from the outlet section 6 and enters the downstream pipeline.

[0056] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0057] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0058] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A centrifugal expander, characterized in that: It comprises a cylinder (8), a base plate (7), a cover plate (9) and a plurality of stationary blades (42); The cylinder (8) is installed between the base plate (7) and the cover plate (9), and an inlet section (2), a flow guide cover (3) and a nozzle ring (4) are arranged in the cylinder (8), wherein one end of the inlet section (2) is connected to the air inlet of the cover plate (9), and the other end of the inlet section (2) is connected to the central through hole of the nozzle ring (4), the flow guide cover (3) is arranged between the impeller (5) and the nozzle ring (4), and the flow guide cover (3) is arranged at the central opening of the base plate (7), and the cylinder (8) is connected to the outlet section (6); An accommodating space for accommodating stationary blades (42) is formed between the guide cover (3) and the nozzle ring (4); a plurality of moving blades (52) are uniformly distributed in the circumferential direction in sequence in the impeller (5); a moving blade medium channel (524) is formed between two adjacent moving blades (52); an annular fluid channel is formed between the nozzle ring (4) and the impeller (5); and an annular pressure diffuser channel is formed between the base plate (7) and the nozzle ring (4); and a medium inflow channel (33) is formed between the inlet section (2), the guide cover (3) and the nozzle ring (4); During operation, the medium passes through the inlet section (2), the medium inflow channel (33), the annular fluid channel, the moving blade medium channel (524) and the annular diffuser channel in sequence and is then discharged through the outlet section (6).

2. The centrifugal expander according to claim 1, characterized in that: The stationary blades (42) are evenly distributed on the inner side surface of the nozzle ring (4) along the circumferential direction with the axis of the nozzle ring (4) as the center line.

3. The centrifugal expander according to claim 2, characterized in that: The center line of the impeller (5) is aligned with the center line of the nozzle ring (4).

4. The centrifugal expander according to claim 3, characterized in that: A main shaft (1) is disposed through the middle of the impeller (5).

5. The centrifugal expander according to claim 4, characterized in that: The main shaft (1) is connected to a power device.

6. The centrifugal expander according to claim 1, characterized in that: The flow area of ​​the medium inflow channel 33 decreases uniformly along the medium flow direction.

7. The centrifugal expander according to claim 1, characterized in that: The nozzle ring (4) includes a stator disk (41), and each stator blade (42) is arranged on the stator disk (41). The stator blade (42) includes a bottom surface of the stator blade, a top surface (423) of the stator blade, a pressure surface (421) of the stator blade, and a suction surface (422) of the stator blade. The stator blade (42) extends outward from the inner end surface of the stator disk (41) and is connected to the inner end surface of the guide cover (3). The top surface (423) of the stator blade is located directly above the bottom surface of the stator blade and the two have the same shape. A gap AC is formed between the pressure surface (421) of the stator blade and the suction surface (422) of the stator blade of adjacent stator blades (42).

8. The centrifugal expander according to claim 7, characterized in that: The cross-sectional area of ​​the gap AC gradually decreases and then increases along the flow direction of the medium.

9. The centrifugal expander according to claim 1, characterized in that: The impeller (5) comprises a wheel cover ring (51), a moving wheel disc (53) and a plurality of moving blades (52), wherein the moving blades (52) comprise a bottom surface of the moving blade, a top surface (521) of the moving blade, a pressure surface (522) of the moving blade and a suction surface (523) of the moving blade, and the moving blades (52) and the stationary blades (42) have the same blade height, an axially extending boss is provided on the top surface (521) of the moving blade, a hole matching the boss is provided on the wheel cover ring (51), and the top surface (521) of the moving blade matches the wheel cover ring (51).

10. The centrifugal expander according to claim 1, characterized in that: The cross-sectional area of ​​the moving blade medium channel (524) first gradually increases and then gradually decreases along the medium flow direction.

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