A centrifugal expander

Abstract

This invention discloses a centrifugal expander. A flow guide is disposed between the impeller and the nozzle ring, and the flow guide is located at the central opening of the substrate. An outlet section is connected to the cylinder. A receiving space for accommodating stationary blades is formed between the flow guide and the nozzle ring. Several moving blades are arranged evenly in sequence along the circumference inside 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. An annular diffusion channel is formed between the substrate and the nozzle ring. A medium inflow channel is formed between the inlet section, the flow guide, and the nozzle ring. 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 diffusion channel in sequence before being discharged through the outlet section. This expander has the characteristics of high expansion ratio, strong work capacity, and adaptability to gas-liquid-solid multiphase media.

Description

Technical Field

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

[0002] Turbine expanders are core equipment in industrial waste heat and energy recovery, energy storage, and other thermodynamic circulation systems. They enable near-isentropic expansion of the working medium, and their conventional structural types include centripetal, axial-flow, and screw types. In recent years, with the continuous changes in application requirements, conventionally structured expanders have been limited in some special application areas. For example, in the process of recovering pressure energy from natural gas at the wellhead, the medium pressure (tens of megapascals) is not only higher than the operating range of conventional turbine expanders, but the medium is also a multiphase, multi-component oil-gas mixture mixed with solid particles. The process involves complex gas-liquid two-phase flow, which causes conventional expanders to experience structural vibration and erosion damage under the alternating fluid excitation forces, affecting the unit's performance and lifespan. In energy storage systems, the expander inlet is often in a supercritical state, with large changes in the specific volume of the medium during expansion, and the expander outlet typically enters a deep two-phase region. This means that a violent gas-liquid phase change occurs inside the expander, resulting in a large amount of liquid gas in the medium. In conventional centripetal expanders, droplets will move radially outward under centrifugal force, opposite to the mainstream flow direction, leading to wear and corrosion of the rotor structure. These application requirements necessitate expanders that meet the conditions of high expansion ratio, large stage enthalpy drop, aerodynamic and geometric compatibility, and the ability to allow multiphase expansion. Compared to centripetal expanders, centrifugal expanders can use centrifugal force to remove impurities and droplets from the medium, making them particularly suitable for multiphase expansion applications.

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

[0004] For example, patent CN 109252900 B discloses "a composite turbine," which uses a single-stage centrifugal-axial flow structure connected in series on the same main shaft, with the high-pressure section using a centrifugal turbine and the low-pressure section using an axial flow turbine. However, the volumetric flow rate of an axial flow turbine changes significantly during expansion, and the blade height changes significantly along the flow direction, forming a non-negligible velocity component along the blade height direction, making cascade design difficult. Furthermore, this centrifugal-axial flow combination makes the unit structure complex and significantly increases the axial dimension, posing a challenge to the safe and stable operation of the equipment. Similar patents with combined structures include CN 104066937B "a method and turbine for expanding 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 drawbacks such as complex internal flow, large unit structure size, and high manufacturing cost. Summary of the Invention

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

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

[0007] The cylinder is installed between the base plate and the cover plate. The cylinder is provided with an inlet section, a flow guide shroud and a nozzle ring. 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 flow guide shroud is located between the impeller and the nozzle ring and is located at the central opening of the base plate. The cylinder is connected to an outlet section.

[0008] The flow guide and the nozzle ring form a receiving space for accommodating stationary blades. Several moving blades are arranged evenly in sequence along the circumference inside 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. An annular diffuser channel is formed between the substrate and the nozzle ring. The inlet section, the flow guide, and the nozzle ring form a medium inflow channel.

[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 before being discharged through the outlet section.

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

[0011] Furthermore, the centerline of the impeller is aligned with the centerline of the nozzle ring.

[0012] Furthermore, a main shaft is provided 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 stationary impeller, and each stationary blade is disposed on the stationary impeller. Each stationary blade includes a blade base surface, a blade tip surface, a pressure surface, and a suction surface. The stationary blade extends outward from the inner end surface of the stationary impeller and connects to the inner end surface of the guide vane. The blade tip surface of the stationary blade is located directly above the blade base surface of the stationary blade and the two have the same shape. A gap AC is formed between the pressure surface and the suction surface of adjacent stationary blades.

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

[0017] Furthermore, the impeller includes a wheel cover ring, a moving impeller disc, and several moving blades. The moving blades include a blade bottom surface, a blade top surface, a pressure surface, and a suction surface. The moving blades and stationary blades have the same blade height. An axially extending boss is provided on the blade top surface of the moving blades. The wheel cover ring has a hole that mates with the boss. The blade top surface of the moving blades mates with the wheel cover ring.

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

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

[0020] In operation, the centrifugal expander of this invention sequentially passes through an inlet section, a medium inflow channel, an annular fluid channel, a moving blade medium channel, and an annular diffuser channel before being discharged through an outlet section. It employs moving and stationary blades and a centrifugal structure that facilitates the movement of droplets and particles. Its axial inflow and radial outflow structure utilizes centrifugal force to separate droplets and particles from the medium, making it suitable for applications involving gas-liquid-solid multiphase media. Furthermore, after passing through the throat of the medium inflow channel, the pressure is further converted into velocity energy, allowing the medium to fully expand within the channel. Therefore, a high expansion ratio, large stage enthalpy drop, and a simple and compact overall structure can be achieved using only a single-stage moving and stationary blade arrangement. Additionally, this invention uses a centrifugal impeller, allowing the medium to fully expand and simultaneously complete a gas-liquid phase change within the medium inflow channel. This avoids large-scale gas-liquid phase changes in rotating components, improving machine stability. The expansion-contraction flow channel effectively utilizes the velocity energy of the medium, resulting in high work capacity and overall efficiency. Attached Figure Description

[0021] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

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

[0023] Figure 2 This is a three-dimensional exploded view of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of the fairing 3;

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

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

[0027] Figure 6 This is a schematic diagram of the nozzle structure;

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

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

[0030] Figure 9 This is a partial view of the moving blade 52.

[0031] Among them, 1 is the main shaft, 2 is the inlet section, 3 is the guide shroud, 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 stationary impeller, 42 is the stationary blade, 421 is the pressure surface of the stationary blade, 422 is the suction surface of the stationary blade, 423 is the blade tip surface of the stationary blade, 424 is the medium channel of the stationary blade, 5 is the impeller, 51 is the wheel cover ring, 52 is the moving blade, 521 is the blade tip 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 medium channel of the moving blade, 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 Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

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

[0035] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0036] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. 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] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0040] Example 1

[0041] refer to Figure 1 The centrifugal expander described herein includes a cylinder 8, a base plate 7, a cover plate 9, and several stationary blades 42. The cylinder 8 is installed between the base plate 7 and the cover plate 9. The cylinder 8 is provided with an inlet section 2, a guide shroud 3, and a nozzle ring 4. 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 shroud 3 is disposed between the impeller 5 and the nozzle ring 4, and is disposed at the central opening of the base plate 7. An outlet section 6 is connected to the cylinder 8. The space between the guide shroud 3 and the nozzle ring 4 forms a space for accommodating stationary blades. The impeller 5 has a space for the blade 42, and a number of moving blades 52 are arranged evenly in a circumferential direction inside 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. An annular diffusion channel is formed between the base plate 7 and the nozzle ring 4. The inlet section 2, the guide shroud 3 and the nozzle ring 4 form a medium inflow channel 33. 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 diffusion channel in sequence and is then discharged through the outlet section 6.

[0042] Example 2

[0043] refer to Figure 1 and Figure 2The centrifugal expander of the present invention includes a main shaft 11, an inlet section 2, a flow guide shroud 3, a nozzle ring 4, an impeller 5, an outlet section 6, and a volute. The volute includes 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. The cylinder 8 is provided with an inlet section 2, a flow guide 3 and a nozzle ring 4. 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 3 is disposed between the impeller 5 and the nozzle ring 4 and is disposed 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 by bolts and an inlet flange. The end of the inlet section 2 is connected to the nozzle ring 4 by bolts. The guide shroud 3 and the nozzle ring 4 form a space for accommodating the stationary blades 42. Each stationary blade 42 is evenly distributed circumferentially on the inner side of the nozzle ring 4 with the axis of the nozzle ring 4 as the center line.

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

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

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

[0049] As one embodiment of the present invention, reference Figure 8 and Figure 9 The impeller 5 includes a wheel cover ring 51, a moving impeller disc 53, and several moving blades 52. Each moving blade 52 includes a blade base surface, a blade tip surface 521, a pressure surface 522, and a suction surface 523, and the moving blades 52 and stationary blades 42 have the same blade height. An axially extending boss is provided on the blade tip surface 521 of the moving blades, and the wheel cover ring 51 has a hole that mates with the boss. The blade tip surface 521 of the moving blades mates with 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 of the pressure surface 522 and the suction surface 521 of the moving blade. The cross-sectional area of ​​the DE section gradually increases along the flow direction, the kinetic energy of the medium is converted into pressure energy, and the relative velocity decreases. The cross-sectional area of ​​the EF section gradually decreases along the flow direction, the pressure energy of the medium is converted into velocity energy, and the relative velocity increases. The relative velocity direction of the medium in the moving blade medium channel 524 changes significantly, from pointing towards the blade pressure surface to pointing in the opposite direction to the rotation of the impeller 5.

[0050] The working principle of this invention is as follows:

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

[0052] b) After the medium passes through the stationary blade medium channel 424, the pressure decreases while the flow velocity 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 peripheral surface of the nozzle ring 4 and the outer peripheral surface of the impeller 5. The high-speed medium impacts the pressure surface 522 of the moving blade and drives 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 diffused in the annular diffusion channel formed by the inner end face of the substrate 7 and the inner end face of the nozzle ring 4, so as to recover the residual velocity of the medium flowing out of the impeller 5 and convert the kinetic energy of the medium into pressure energy.

[0055] e) After the medium flows out of the annular diffuser channel, it turns 90 degrees and enters the volute 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] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0057] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0058] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A centrifugal expander, characterized in that, It includes a cylinder (8), a base plate (7), a cover plate (9), and several stationary blades (42); The cylinder (8) is installed between the base plate (7) and the cover plate (9). The cylinder (8) is provided with an inlet section (2), a flow guide (3) and a nozzle ring (4). 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 (3) is located between the impeller (5) and the nozzle ring (4). The flow guide (3) is located at the central opening of the base plate (7). The cylinder (8) is connected to an outlet section (6). The flow guide (3) and the nozzle ring (4) form a receiving space for accommodating the stationary blades (42). The impeller (5) is provided with a number of moving blades (52) evenly 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). An annular diffusion channel is formed between the substrate (7) and the nozzle ring (4). The inlet section (2), the flow guide (3) and the nozzle ring (4) form a medium inflow channel (33). 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 before being discharged through the outlet section (6); The nozzle ring (4) includes a stationary disk (41), and each stationary blade (42) is disposed on the stationary disk (41). The stationary blade (42) includes a bottom surface of the stationary blade, a top surface of the stationary blade (423), a pressure surface of the stationary blade (421), and a suction surface of the stationary blade (422). The stationary blade (42) extends outward from the inner end surface of the stationary disk (41) and is connected to the inner end surface of the guide shroud (3). The top surface of the stationary blade (423) is located directly above the bottom surface of the stationary blade and the two have the same shape. A gap AC is formed between the pressure surface (421) and the suction surface (422) of the stationary blade of the adjacent stationary blade (42). The cross-sectional area of ​​the gap AC gradually decreases and then gradually increases along the direction of medium flow. The cross-sectional area of ​​the moving blade medium channel (524) gradually increases and then gradually decreases along the medium flow direction.

2. The centrifugal expander according to claim 1, characterized in that, Each stationary blade (42) is evenly distributed circumferentially on the inner side of the nozzle ring (4) with the axis of the nozzle ring (4) as the center line.

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

4. The centrifugal expander according to claim 3, characterized in that, The impeller (5) has a main shaft (1) running through its middle section.

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 impeller (5) includes a wheel cover ring (51), a moving wheel disc (53), and several moving blades (52). The moving blades (52) include the blade bottom surface, the blade top surface (521), the pressure surface (522), and the suction surface (523). The moving blades (52) and the stationary blades (42) have the same blade height. An axially extending boss is provided on the blade top surface (521) of the moving blade. The wheel cover ring (51) has a hole that matches the boss. The blade top surface (521) of the moving blade matches the wheel cover ring (51).

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