A turboexpander unit and a method for enhancing stability of a dynamic pressure gas bearing
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-10
- Publication Date
- 2026-08-11
AI Technical Summary
两种主流的制动方法，风机轮排出的气体都没有得到充分的利用，浪费了膨胀机转换的部分能量
该透平膨胀机机组将风机轮替换为离心压缩轮，通过回收压缩轮出口的高压气体，通入机壳内动压气浮轴承空腔区域，从而提高动压气浮轴承的承载能力，增强轴承的稳定性，并且压缩气体可用于平衡叶轮轮背气体泄露对叶轮的轴向力，保持气体轴承区域气压的动态平衡调节。
Smart Images
Figure CN122543813A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gas bearing technology and high-speed rotating machinery, and in particular to a turbine expander unit and a method for enhancing the stability of a hydrodynamic air bearing. Background Technology
[0002] In both ambient and cryogenic applications, turbo expanders require high rotor speeds to ensure optimal performance, achieving high efficiency while extracting energy. Currently, most high-speed turbo expanders utilize air-bearing bearings. These air-bearing bearings replace traditional grease-lubricated bearings, using gas as the lubricating medium. This reduces maintenance costs and environmental impact, makes them suitable for various temperature ranges, and prevents frictional wear during high-speed rotor operation, thus increasing the expander's reliability.
[0003] However, air bearings have low load-bearing capacity and low film stiffness, making them prone to instability after significant external impacts, which can damage the turbine expander rotor. Air bearings are divided into hydrodynamic bearings and hydrostatic bearings. Hydrodynamic bearings have better impact resistance than hydrostatic bearings, and their load-bearing capacity and stability can be further improved by increasing the ambient pressure.
[0004] Most existing high-speed turboexpanders employ a blower-based braking system, where the blower impeller draws in air from the atmosphere, compresses it, and then directly discharges it back into the atmosphere. Alternatively, the blower side of the turboexpander is looped, meaning the inlet and outlet of the blower impeller form a closed loop. This allows for braking while simultaneously adjusting the characteristic ratio of the turboexpander, which is beneficial for studying its rotational characteristics and optimizing its operating efficiency. However, in both of these mainstream braking methods, the exhaust gas from the blower impeller is not fully utilized, wasting some of the energy converted by the expander.
[0005] Based on the aforementioned problems in related technologies, this case proposes a method for recovering this energy by using a turboexpander unit and enhancing the stability of the dynamic pressure air bearing. The fan impeller is replaced with a centrifugal compressor impeller, and the high-pressure gas at the outlet of the compressor impeller is recovered and introduced into the cavity area of the dynamic pressure air bearing inside the casing, thereby improving the load-bearing capacity of the dynamic pressure air bearing and enhancing its stability. Furthermore, the compressed gas can be used to balance the axial force of the impeller caused by gas leakage on the impeller back, maintaining the dynamic balance and regulation of the gas pressure in the gas bearing area.
[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0007] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.
[0008] This invention aims to provide a turbo expander unit and a method for enhancing the stability of the dynamic pressure air bearing. By recovering the high-pressure gas from the outlet of the centrifugal compressor wheel on the compression side of the turbo expander and introducing it into the cavity area of the dynamic pressure bearing and the inlet of the compressor wheel, the load-bearing capacity of the dynamic pressure bearing is improved, the axial force of the main shaft is dynamically balanced, and the resulting fan braking main circuit can change the characteristic ratio of the expander, improve the energy utilization rate and working efficiency of the expander, and enhance the stability of the rotor dynamic pressure bearing.
[0009] To achieve the above objectives, the present invention proposes the following technical solution: a turbine expander unit, characterized in that: the unit includes a housing (1), a compression wheel (2), a main shaft (3), a compression-side radial bearing (4), a compression-side thrust bearing (5), a turbine-side thrust bearing (6), a turbine-side radial bearing (7), an expansion wheel (8), a turbine-side pressure control valve (9), a compression-side pressure control valve (10), an exhaust pipe B (11), and an exhaust pipe A. (12), heat exchanger (13), exhaust pipe C (14), air tank (15), air supply regulating valve (16), pressure reducing valve (17), exhaust pipe D (18), wherein, the turbine expander main shaft (3) is sequentially equipped with compression wheel (2), compression side radial bearing (4), compression side thrust bearing (5), turbine side thrust bearing (6), turbine side radial bearing (7) and expansion wheel (8), the exhaust pipe A (12) on the left side of the casing (1) is connected to the outlet of compression wheel (2), the heat exchanger (13) is installed on the exhaust pipe A (12), the exhaust pipe A (12) flows into the air tank (15) after passing through the heat exchanger (13), the air tank (15) The exhaust pipes B (11) are connected to the two branch exhaust pipes, each with a pressure control valve (10) and (9), which respectively enter the gas bearing area on the compression side and the gas bearing area on the turbine side inside the housing. Then, the exhaust pipes are discharged from the housing (1) through the exhaust pipe C (14) and connected to the exhaust pipe D (18). The gas tank (15) is connected to the gas supply regulating valve (16), the pressure reducing valve (17), the exhaust pipe A (12), the exhaust pipe B (11), and the exhaust pipe D (18). The gas tank (15) is connected to the inlet of the compression wheel (2) through the exhaust pipe D (18). The housing (1), the compression wheel (2), the exhaust pipe A (12), the gas tank (15), and the exhaust pipe B (18) are connected. (11), the compression side pressure control valve (10), the turbine side pressure control valve (9), the exhaust pipe C (14), the pressure reducing valve (17) and the exhaust pipe D (18) constitute the compression side bearing induced air branch circuit; the casing (1), the compression wheel (2), the heat exchanger (13), the exhaust pipe A (12), the air tank (15), the pressure reducing valve (17) and the exhaust pipe D (18) constitute the compression side braking main circuit; A method for enhancing the stability of a turbine expander dynamic gas bearing system, characterized in that: the turbine expander unit further includes the following steps: (1) The gas from the outlet of the compression wheel (2) flows into the exhaust pipe D (12), is cooled by the heat exchanger (13), and flows into the gas storage tank (15) to slow down the airflow speed and stabilize the airflow pressure; (2) The airflow in the gas storage tank (15) flows into the air bearing cavity area inside the housing (1) through the two branches of the exhaust pipe B (11), pressurizing the bearing environment. The gas storage tank (15) can be supplemented with gas from outside the system through the gas replenishment regulating valve (16). (3) The gas environment of the compression side radial bearing (4), compression side thrust bearing (5), turbine side thrust bearing (6), and turbine side radial bearing (7) is connected, and the pressurized gas is provided by the two branches of the exhaust pipe B (11). (4) The turbine-side pressure control valve (9) and the compression-side pressure control valve (10) on the two branches of the exhaust pipe B (11) control the output pressure through the input signal to maintain the balance and stability of the gas bearing environment on the turbine side and the compression side. (5) The gas in the gas bearing cavity area inside the housing (1) is introduced through the exhaust pipe B (11), discharged through the exhaust pipe C (14) and merged into the exhaust pipe D (18), and together with the gas in the exhaust pipe D (18), enters the inlet area of the compression wheel (2) to form the compression side bearing induced air circuit. (6) The gas storage tank (15) is connected to the exhaust pipe A (12), exhaust pipe B (11) and exhaust pipe D (18). The exhaust pipe D (18) has a pressure reducing valve (17) to control the airflow pressure and flow rate, and enters the inlet of the compression wheel (2) inside the housing (1) to form the compression side braking main circuit.
[0010] Furthermore, the two branches of the exhaust pipe B (11) and the exhaust pipe C (14) are respectively connected to the compression side gas bearing area and the turbine side gas bearing area inside the housing (1).
[0011] Furthermore, a labyrinth seal spacer is provided between the compression wheel (2) and the compression-side radial gas bearing (4), and between the expansion wheel (8) and the turbine-side radial gas bearing (7); or sealing gas is continuously introduced between the compression wheel (2) and the compression-side radial gas bearing (4), and between the expansion wheel (8) and the turbine-side radial gas bearing (7) to dynamically balance the pressure.
[0012] Furthermore, the pressure reducing valve (17) controls the pressure and gas flow rate at the inlet of the compression wheel in the main braking circuit.
[0013] Furthermore, the gas storage tank (15) can replenish gas from the outside to the compression side braking main circuit through the gas replenishment regulating valve (16).
[0014] Furthermore, the working fluid of the turboexpander unit can be air, helium, hydrogen, or other gases.
[0015] The turbine expander unit and the method for enhancing the stability of the turbine expander's moving air bearing provided by this invention can achieve the following technical effects: This turboexpander unit replaces the fan impeller with a centrifugal compressor impeller. By recovering the high-pressure gas from the compressor impeller outlet and introducing it into the dynamic pressure air bearing cavity area inside the casing, the load-bearing capacity of the dynamic pressure air bearing is improved, the stability of the bearing is enhanced, and the compressed gas can be used to balance the axial force of the impeller caused by gas leakage on the impeller back, maintaining the dynamic balance and regulation of the gas pressure in the gas bearing area.
[0016] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of a turbine expander unit structure that utilizes a method to enhance the stability of a turbine expander's dynamic pressure air bearing, as provided in an embodiment of this disclosure.
[0018] Figure 2 This is a schematic diagram of the structure of the gas storage tank provided in the embodiments of this disclosure.
[0019] Figure 3 This is a schematic diagram of the structure of the heat exchanger provided in the embodiments of this disclosure.
[0020] Figure 4 This is a schematic diagram of the structure of the radial air bearing with dynamic pressure foil provided in the embodiments of this disclosure.
[0021] Figure 5 This is a schematic diagram of the structure of the dynamic pressure foil thrust air bearing provided in the embodiments of this disclosure.
[0022] Figure label: 1-Casing, 2-Compression impeller, 3-Main shaft, 4-Compression side radial bearing, 5-Compression side thrust bearing, 6-Turbine side thrust bearing, 7-Turbine side radial bearing, 8-Expansion impeller, 9-Turbine side pressure control valve, 10-Compression side pressure control valve, 11-Exhaust pipe B, 12-Exhaust pipe A, 13-Heat exchanger, 14-Exhaust pipe C, 15-Air tank, 16-Make-up air regulating valve, 17-Pressure reducing valve, 18-Exhaust pipe D. Detailed Implementation
[0023] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.
[0024] like Figure 1As shown, this invention provides a turbine expander unit and a method for enhancing the stability of dynamic pressure air bearings. In the turbine expander unit using this method, a turbine expander rotor main shaft 3 is installed inside the casing 1. The turbine expander main shaft 3 is sequentially equipped with a centrifugal compression wheel 2, a compression-side radial bearing 4, a compression-side thrust bearing 5, a turbine-side thrust bearing 6, a turbine-side radial bearing 7, and a working expansion wheel 8. The unit also includes a turbine-side pressure control valve 9, a compression-side pressure control valve 10, an exhaust pipe B11, an exhaust pipe A12, a heat exchanger 13, and an exhaust pipe C. 14. Gas storage tank; 15. Gas replenishment regulating valve; 16. Pressure reducing valve; 17. Exhaust pipe D18. The turbine expander main shaft 3 is sequentially equipped with a compression wheel 2, a compression-side radial bearing 4, a compression-side thrust bearing 5, a turbine-side thrust bearing 6, a turbine-side radial bearing 7, and an expansion wheel 8. The exhaust pipe D18 on the left side of the casing 1 is connected to the outlet of the compression wheel 2. A heat exchanger 13 is installed on the exhaust pipe A12. After passing through the heat exchanger 13, the exhaust pipe A12 flows into the gas storage tank 15. The gas storage tank 15 is connected to two branches. The exhaust pipe B11 of the circuit is equipped with pressure control valves 10 and 9, which respectively lead to the gas bearing area on the compression side and the gas bearing area on the turbine side inside the housing. Then, it is discharged from the housing 1 to the gas storage tank 15 through the exhaust pipe C15. The gas storage tank 15 is connected to the air supply regulating valve 16, the pressure reducing valve 17, the exhaust pipe A12, the exhaust pipe B11, and the exhaust pipe D18. The gas storage tank 15 is connected to the inlet of the compression wheel 2 through the exhaust pipe D18. The housing 1, the compression wheel 2, the exhaust pipe A12, the gas storage tank 15, the exhaust pipe B11, the compression side pressure control valve 10, the turbine side pressure control valve 9, the exhaust pipe C14, the pressure reducing valve 17, and the exhaust pipe D18 constitute the compression side bearing induced air branch circuit. The housing 1, the compression wheel 2, the heat exchanger 13, the exhaust pipe A12, the gas storage tank 15, the pressure reducing valve 17, and the exhaust pipe D18 constitute the compression side braking main circuit.
[0025] Furthermore, the present invention also provides a method for enhancing the stability of a turbine expander dynamic gas bearing system, including the above-mentioned unit, and further comprising the following steps: (1) The gas from the outlet of the compression wheel 2 flows into the exhaust pipe D12, is cooled by the heat exchanger 13, and flows into the gas storage tank 15 to slow down the airflow speed and stabilize the airflow pressure. (2) The airflow in the gas storage tank 15 flows into the air bearing cavity area inside the housing 1 through the two branches of the exhaust pipe B11, pressurizing the bearing environment. The gas storage tank 15 can be replenished with gas from outside the system through the gas replenishment regulating valve 16. (3) The gas environment of the compression side radial bearing 4, the compression side thrust bearing 5, the turbine side thrust bearing 6, and the turbine side radial bearing 7 is connected, and the pressurized gas is provided by the two branches of the exhaust pipe B11. (4) The turbine-side pressure control valve 9 and the compression-side pressure control valve 10 on the two branches of the exhaust pipe B11 control the output pressure through input signals to maintain the balance and stability of the gas bearing environment on the turbine side and the compression side. (5) The gas in the gas bearing cavity area inside the housing 1 is introduced through the exhaust pipe B11, discharged through the exhaust pipe C14 and merged into the exhaust pipe D18, and enters the inlet area of the compression wheel 2 together with the gas in the exhaust pipe D18 to form the compression side bearing induced air circuit. (6) The gas storage tank 15 is connected to the exhaust pipe A12, exhaust pipe B11 and exhaust pipe D18. The exhaust pipe D18 has a pressure reducing valve 17 to control the air pressure and flow rate, and enters the inlet of the compression wheel 2 inside the housing 1 to form the compression side braking main circuit.
[0026] Optionally, the two branches of the exhaust pipe B11 and the exhaust pipe C14 are respectively connected to the compression side gas bearing area and the turbine side gas bearing area inside the housing 1.
[0027] Furthermore, a labyrinth seal sleeve is provided between the compression wheel 2 and the compression-side radial gas bearing 4, and between the expansion wheel 8 and the turbine-side radial gas bearing 7; or sealing gas is continuously introduced between the compression wheel 2 and the compression-side radial gas bearing 4, and between the expansion wheel 8 and the turbine-side radial gas bearing 7, to dynamically balance the pressure.
[0028] Optionally, the pressure reducing valve 17 controls the pressure and gas flow rate at the inlet of the compression wheel in the main braking circuit.
[0029] Optionally, the gas storage tank 15 can be supplied with gas from the outside to the compression-side braking main circuit through the gas replenishment regulating valve 16.
[0030] Optionally, the working fluid of the turboexpander unit may be air, helium, hydrogen, or other gases.
[0031] Under operating conditions, the compressed gas from the outlet of the centrifugal compressor wheel 2 is discharged from the casing 1 through the exhaust pipe A12, undergoes isobaric cooling through the heat exchanger 13 to reduce airflow velocity and turbulence, and then enters the gas storage tank 15. The gas storage tank 15 has a gas replenishment regulating valve 16 to replenish the working gas in the circuit. This gas can be air, helium, hydrogen, or other gases. The gas storage tank 15 has two outlet pipes. A small flow of gas in one branch passes through the exhaust pipe B11 and pressure control valves 9 and 10 into the compression and turbine-side dynamic pressure bearing cavities inside the casing 1. The pressure control valves control the output pressure through input signals to maintain a stable and balanced gas bearing environment on the turbine and compression sides. The gas entering the bearing cavities passes through the exhaust pipe... C14 flows out of the casing 1 and merges into the exhaust pipe D18; the main gas from the gas storage tank 15 enters the inlet area of the compression wheel 2 through the exhaust pipe D18, forming a complete compression-side bearing induced gas branch circuit and braking main circuit, which can adjust the characteristic ratio of the expander to keep the expander working efficiency at its best. The exhaust pipe D18 is connected to the exhaust pipe C14, and the flow rate of the bearing environment outlet gas is very small, which can be directly sucked into the inlet of the compression wheel 2. The exhaust pipe D18 is equipped with a pressure reducing valve 17 to control the pressure and flow rate of the compression wheel inlet in the circuit. When the expander stops working or malfunctions, the valve can be quickly closed to reduce the gas inlet of the compression wheel 2, realize rapid braking, and ensure the stability and safety of the turbine expander.
[0032] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.
Claims
1. A turboexpander unit, characterized by: The unit includes a housing (1), a compression wheel (2), a main shaft (3), a compression-side radial bearing (4), a compression-side thrust bearing (5), a turbine-side thrust bearing (6), a turbine-side radial bearing (7), an expansion wheel (8), a turbine-side pressure control valve (9), a compression-side pressure control valve (10), an exhaust pipe B (11), and an exhaust pipe A. (12), heat exchanger (13), exhaust pipe C (14), air tank (15), air supply regulating valve (16), pressure reducing valve (17), exhaust pipe D (18), wherein, the turbine expander main shaft (3) is sequentially equipped with compression wheel (2), compression side radial bearing (4), compression side thrust bearing (5), turbine side thrust bearing (6), turbine side radial bearing (7) and expansion wheel (8), the exhaust pipe A (12) on the left side of the casing (1) is connected to the outlet of compression wheel (2), the heat exchanger (13) is installed on the exhaust pipe A (12), the exhaust pipe A (12) flows into the air tank (15) after passing through the heat exchanger (13), the air tank (15) The exhaust pipes B (11) are connected to the two branch exhaust pipes, each with a pressure control valve (10) and (9), which respectively enter the gas bearing area on the compression side and the gas bearing area on the turbine side inside the housing. Then, the exhaust pipes are discharged from the housing (1) through the exhaust pipe C (14) and connected to the exhaust pipe D (18). The gas tank (15) is connected to the gas supply regulating valve (16), the pressure reducing valve (17), the exhaust pipe A (12), the exhaust pipe B (11), and the exhaust pipe D (18). The gas tank (15) is connected to the inlet of the compression wheel (2) through the exhaust pipe D (18). The housing (1), the compression wheel (2), the exhaust pipe A (12), the gas tank (15), and the exhaust pipe B (18) are connected. (11), the compression side pressure control valve (10), the turbine side pressure control valve (9), the exhaust pipe C (14), the pressure reducing valve (17) and the exhaust pipe D (18) constitute the compression side bearing induced air branch circuit; the casing (1), the compression wheel (2), the heat exchanger (13), the exhaust pipe A (12), the air tank (15), the pressure reducing valve (17) and the exhaust pipe D (18) constitute the compression side braking main circuit; A method for enhancing the stability of a turbine expander dynamic gas bearing system, characterized in that: the turbine expander unit further includes the following steps: (1) The gas from the outlet of the compression wheel (2) flows into the exhaust pipe D (12), is cooled by the heat exchanger (13), and flows into the gas storage tank (15) to slow down the airflow speed and stabilize the airflow pressure; (2) The airflow in the gas storage tank (15) flows into the air bearing cavity area inside the housing (1) through the two branches of the exhaust pipe B (11), pressurizing the bearing environment. The gas storage tank (15) can be supplemented with gas from outside the system through the gas replenishment regulating valve (16). (3) The gas environment of the compression side radial bearing (4), compression side thrust bearing (5), turbine side thrust bearing (6), and turbine side radial bearing (7) is connected, and the pressurized gas is provided by the two branches of the exhaust pipe B (11). (4) The turbine-side pressure control valve (9) and the compression-side pressure control valve (10) on the two branches of the exhaust pipe B (11) control the output pressure through the input signal to maintain the balance and stability of the gas bearing environment on the turbine side and the compression side. (5) The gas in the gas bearing cavity area inside the housing (1) is introduced through the exhaust pipe B (11), discharged through the exhaust pipe C (14) and merged into the exhaust pipe D (18), and together with the gas in the exhaust pipe D (18), enters the inlet area of the compression wheel (2) to form the compression side bearing induced air circuit. (6) The gas storage tank (15) is connected to the exhaust pipe A (12), exhaust pipe B (11) and exhaust pipe D (18). The exhaust pipe D (18) has a pressure reducing valve (17) to control the airflow pressure and flow rate, and enters the inlet of the compression wheel (2) inside the housing (1) to form the compression side braking main circuit.
2. The turboexpander unit of claim 1, wherein: The two branches of the exhaust pipe B (11) and exhaust pipe C (14) are respectively connected to the gas bearing area on the compression side and the gas bearing area on the turbine side inside the housing (1).
3. The turboexpander unit of claim 1, wherein: A labyrinth seal sleeve is provided between the compression wheel (2) and the compression-side radial gas bearing (4), and between the expansion wheel (8) and the turbine-side radial gas bearing (7); or sealing gas is continuously introduced between the compression wheel (2) and the compression-side radial gas bearing (4), and between the expansion wheel (8) and the turbine-side radial gas bearing (7) to dynamically balance the pressure.
4. The turboexpander unit of claim 1, wherein: The pressure reducing valve (17) controls the pressure and gas flow at the inlet of the compression wheel in the main braking circuit.
5. The turboexpander unit of claim 1, wherein: The gas storage tank (15) can replenish gas from the outside to the compression side braking main circuit through the gas replenishment regulating valve (16).
6. The turboexpander unit of claim 1, wherein: The working fluid of the turboexpander unit can be air, helium, hydrogen or other gases.