Journal and thrust gas bearings

Abstract

To provide improved bearings for use in turbomachines configured to reduce air leakage through the bearings, decrease the footprint of the bearings, increase the gap pressure in the bearings, and / or increase the damping characteristics of the bearings.SOLUTION: A bearing 202 includes a thrust gas bearing 220 attached to a journal bearing 222, and two or more converging-diverging orifices defined in a surface of at least one of the thrust gas bearing and the journal bearing. The converging-diverging orifices supply at least one pressurized gas to an interior of the bearing. Hydrodynamic lifting grooves are provided on the faces of the thrust gas bearing and the journal bearing and provide improved load capacity and sealing capabilities. Control over the ratios of the pressurized gases provides additional sealing capabilities and reduced leakage. A metal mesh damper provides increased damping of the gas bearing.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 942,817, filed December 3, 2019, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates generally to thrust and journal bearings, and more particularly to connected journal and thrust gas bearings having converging-diverging orifice geometries, and turbomachinery operating therewith. [Background technology]

[0003] Turbomachinery, such as centrifugal (fluid) compressors (centrifugal flow compressors), axial flow compressors, and turbines, can be utilized in a variety of industries. In particular, centrifugal compressors and turbines are widely used in power plants, jet engine applications, gas turbines, and automotive applications. Centrifugal compressors and turbines are also commonly used in large-scale industrial applications, such as air separation plants and hot gas expanders used in the petroleum refining industry. Centrifugal compressors are also used in large-scale industrial applications, such as refineries and chemical plants.

[0004] Referring to FIG. 1, a multi-stage centrifugal flow turbomachine 10 is illustrated according to conventional design. Some applications may utilize a single stage. Other applications may utilize multiple stages. Such turbomachines 10 generally include a shaft 20 supported within a housing 30 by a pair of bearings 40. The turbomachine 10 shown in FIG. 1 includes multiple stages for incrementally increasing the pressure of a working fluid. The stages are arranged sequentially along the longitudinal axis of the turbomachine 10, and all stages may or may not have similar components that operate according to the same principles.

[0005] Continuing to refer to FIG. 1 , the impeller 50 includes a plurality of circumferentially arranged rotating blades 60 mounted on an impeller hub 70 attached to the shaft 20. The blades 60 may be optionally attached to a cover 65. The plurality of impellers 50 may be spaced in stages along the axial length of the shaft 20. The rotating blades 60 are fixedly coupled to the impeller hub 70 such that the rotating blades 60, together with the impeller hub 70, rotate with rotation of the shaft 20. The rotating blades 60 rotate downstream of a plurality of stationary vanes or stators 80 mounted on a stationary tubular casing. A working fluid, such as a gas mixture, flows radially into and out of the turbomachine 10 along the shaft 20. The rotating blades 60 are rotated relative to the stator 80 using mechanical power transferred to the fluid. In a centrifugal compressor, the cross-sectional area between the rotating blades 60 in the impeller 50 decreases from the inlet end to the discharge end, resulting in compression of the working fluid as it passes through the impeller 50.

[0006] Referring to FIG. 2 , a working fluid, such as a gas mixture, travels from an inlet end 90 to an outlet end 100 of a turbomachine 10. A row of stators 80 at the inlet end 90 directs the working fluid to a row of rotating blades 60 of the turbomachine 10. The stators 80 extend into a casing to direct the working fluid to the rotating blades 60. The stators 80 are spaced circumferentially between individual struts around the casing at approximately equal intervals. A diffuser 110 is provided at the outlet of the rotating blades 60 to convert excess kinetic energy from the fluid flow leaving the rotating blades 60 into a pressure increase. The diffuser 110 optionally includes a plurality of diffuser blades 120 extending into the casing. The diffuser blades 120 are spaced circumferentially, typically with equal spacing between each diffuser blade 120 around the diffuser casing. In a multi-stage turbomachine 10, a plurality of return channel vanes 125 are provided at the outlet end 100 of the fluid compression stage to direct the working fluid to the rotating blades 60 of the next successive stage. In such an implementation, the return channel vanes 125 provide the function of the stator 80 from the first stage of the turbomachine 10. The final impeller of a multi-stage turbomachine 10 typically has only a diffuser, which may or may not be provided with diffuser blades 120. The final diffuser directs the working fluid flow into a discharge casing (volute) having a discharge flange for connection to a discharge pipe. As shown in FIG. 2, in a single-stage implementation, the turbomachine 10 includes a stator 80 at the inlet end 90 and a diffuser 110 at the outlet end 100.

[0007] The purpose of bearings in turbomachinery applications is to support the rotating rotor reliably with minimal friction and provide the necessary stiffness and damping characteristics for low vibration. The majority of turbomachinery bearings utilize oil for this purpose. Gas bearings are bearings in which the working fluid is a gas (rather than oil) to achieve separation between the rotor and bearing surface. This eliminates the need for oil lubrication.

[0008] Gas bearings of various designs have been studied in the turbomachinery industry for decades. Turbomachinery utilizes both journal and thrust gas bearings. Typically in turbomachinery, the thrust and journal bearings are separate from each other. Gas bearings are of particular interest for turbomachinery due to their cleanliness, wider temperature tolerance without a lubricant circulation system, potentially lower cost, and lower maintenance. Typical gas-lubricated bearings can be hydrodynamic or hydrostatic.

[0009] Hydrodynamic gas bearings, such as foil bearings, are bearings that rely on relatively high speeds of the rotating shaft journal to entrain and pressurize the air between the shaft and bearing surface, creating separation between these surfaces. However, in many heavy turbomachinery applications, relatively high surface speeds and / or journal diameters are required to generate load-carrying capacity. Additionally, these hydrodynamic means cannot support the rotor at low speeds, which can lead to limited bearing life due to contact during start-up and shutdown.

[0010] Hydrostatic bearings, on the other hand, are externally pressurized. In hydrostatic bearings, the working fluid is pressurized outside the bearing (typically by a separate compressor or pump) and delivered to the space between the shaft and the bearing surface. Supply gas at sufficient supply pressure can support the rotor with a thin gas film over the entire speed range (even at rest). The lower viscosity of gas compared to oil lubricants allows for nearly frictionless rotation compared to bearings with a conventional oil film. This gas can escape from the bearing, resulting in supply gas leakage.

[0011] Hydrostatic bearings also provide reduced damping of the rotor bearing system's lateral natural frequencies compared to hydrodynamic bearings. Hydrodynamic bearings with metal mesh backings have been shown to increase the damping characteristics of hydrodynamic bearings.

[0012] The pressurized air flow in an aerostatic bearing is often restricted. This restriction refers to restricting the air flow from the source to the gap. This creates a reserve pressure behind the gap. As the load on one orifice increases, the gap decreases. The presence of reserve pressure allows the pressure at the loaded orifice to increase to compensate for this additional load. This restriction and compensation gives the aerostatic bearing its stiffness. Summary of the Invention

[0013] According to one example of the present disclosure, an improved bearing for use in a turbomachine is provided, which may be configured to reduce air leakage through the bearing, reduce the bearing footprint, increase gap pressure within the bearing, and / or increase the damping characteristics of the bearing compared to current technology.

[0014] According to another example of the present disclosure, there is provided a bearing that addresses each of the above-mentioned improvements combined into a single bearing. According to this example, the bearing may be made of a thrust gas bearing mounted on a journal bearing. Combining the thrust and journal bearings in this manner reduces the footprint of the combined bearing.

[0015] According to a particular example of the present disclosure, a bearing is provided that includes a thrust gas bearing mounted to a journal bearing and two or more converging-diverging orifices defined in a surface of at least one of the thrust gas bearing and the journal bearing, the converging-diverging orifices supplying at least one pressurized gas to an interior of the bearing.

[0016] The at least one pressurized gas may include a process gas.

[0017] Each of the converging-diverging orifices may include a throat, and each orifice is configured to cause the flow velocity of the at least one pressurized gas within the throat of the orifice to be Mach 1 (340.29 m / s) and the flow velocity of the at least one pressurized gas through the throat to be supersonic.

[0018] The thrust gas bearing may include hydrodynamic lifting grooves on a surface of the thrust gas bearing, the hydrodynamic lifting grooves configured to create a gas seal.

[0019] The thrust gas bearing may be configured to receive at least one hydrostatic injection of pressurized gas to form a gas seal within the thrust gas bearing.

[0020] The edge of the inner surface of the journal bearing may include a plurality of grooves defined therein, the grooves having a shape that creates a high pressure area at the edge of the journal bearing.

[0021] The converging-diverging orifices can include at least one inner orifice and at least one outer orifice. The at least one pressurized gas can include a process gas supplied through the at least one inner orifice and a clean air gas supplied through the at least one outer orifice. When the process gas has a higher pressure than the clean air gas, the process gas prevents the clean air gas from leaking into the bearing.

[0022] The converging-diverging orifice can include at least one inner orifice and at least one outer orifice. The at least one pressurized gas can include a process gas supplied through the at least one inner orifice and a clean air gas supplied through the at least one outer orifice. When the clean air gas has a higher pressure than the process gas, the clean air gas prevents the process gas from leaking from within the bearing.

[0023] The converging-diverging orifice may include at least one inner orifice, at least one outer orifice, and at least one seal gas orifice located between the at least one inner orifice and the at least one outer orifice. The at least one pressurized gas may include a process gas supplied through the at least one inner orifice, a clean air gas supplied through the at least one outer orifice, and a seal gas supplied through the at least one seal gas orifice. When the seal gas has a higher pressure than the process gas and the clean air gas, the seal gas prevents the process gas from leaking from within the bearing.

[0024] The outer surface of the bearing may be provided with a metal mesh damper.

[0025] According to a specific example of the present disclosure, a turbomachine is provided. The turbomachine includes a casing having an inlet tip and an outlet tip opposite the inlet tip along a longitudinal axis of the casing, a shaft disposed within the casing and extending from the inlet tip to the outlet tip of the casing, at least one rotor extending radially outward from the shaft, and at least one bearing. The bearing includes a thrust gas bearing mounted on the journal bearing and two or more converging-diverging orifices defined in a surface of at least one of the thrust gas bearing and the journal bearing. The converging-diverging orifices supply at least one pressurized gas to an interior of the bearing. The rotor is housed within the thrust gas bearing. The shaft is at least partially housed within the journal bearing.

[0026] The at least one pressurized gas may include a process gas.

[0027] Each of the converging-diverging orifices may include a throat, and each orifice is configured to cause the flow velocity of at least one pressurized gas within the throat of the orifice to be Mach 1 and the flow velocity of the at least one pressurized gas through the throat to be supersonic.

[0028] The thrust gas bearing may include a hydrodynamic lifting groove on a surface of the thrust gas bearing, the hydrodynamic lifting groove configured to create a gas seal.

[0029] The thrust gas bearing may be configured to receive at least one hydrostatic injection of pressurized gas to form a gas seal within the thrust gas bearing.

[0030] The edge of the inner surface of the journal bearing may include a plurality of grooves defined therein, the grooves having a shape that creates a high pressure area at the edge of the journal bearing.

[0031] The converging-diverging orifices can include at least one inner orifice and at least one outer orifice. The at least one pressurized gas can include a process gas supplied through the at least one inner orifice and a clean air gas supplied through the at least one outer orifice. When the process gas has a higher pressure than the clean air gas, the process gas prevents the clean air gas from leaking into the bearing.

[0032] The converging-diverging orifice can include at least one inner orifice and at least one outer orifice. The at least one pressurized gas can include a process gas supplied through the at least one inner orifice and a clean air gas supplied through the at least one outer orifice. When the clean air gas has a higher pressure than the process gas, the clean air gas prevents the process gas from leaking from within the bearing.

[0033] The converging-diverging orifice may include at least one inner orifice, at least one outer orifice, and at least one seal gas orifice located between the at least one inner orifice and the at least one outer orifice. The at least one pressurized gas may include a process gas supplied through the at least one inner orifice, a clean air gas supplied through the at least one outer orifice, and a seal gas supplied through the at least one seal gas orifice. When the seal gas has a higher pressure than the process gas and the clean air gas, the seal gas prevents the process gas from leaking from within the bearing.

[0034] The outer surface of the bearing may be provided with a metal mesh damper.

[0035] The turbomachine may further include a metal mesh damper disposed on an outer surface of the bearing.

[0036] Further preferred, non-limiting embodiments or aspects are described in the following numbered paragraphs:

[0037] (1) A bearing comprising a thrust gas bearing mounted on a journal bearing and two or more converging-diverging orifices defined in the surface of at least one of the thrust gas bearing and the journal bearing, wherein the converging-diverging orifices supply at least one pressurized gas to the interior of the bearing.

[0038] (2) The bearing according to (1) above, wherein the at least one pressurized gas includes a process gas.

[0039] (3) A bearing as described in (1) or (2) above, wherein the converging-diverging orifices each have a throat, and each orifice is configured to cause the flow velocity of at least one pressurized gas in the throat of the orifice to be Mach 1, and to cause the flow velocity of the at least one pressurized gas passing through the throat to be supersonic.

[0040] (4) A bearing according to any one of (1) to (3) above, wherein the thrust gas bearing has a hydrodynamic lifting groove on the surface of the thrust gas bearing, and the hydrodynamic lifting groove is configured to form a gas seal.

[0041] (5) A bearing according to any one of (1) to (4) above, wherein the thrust gas bearing is configured to receive hydrostatic injection of the at least one pressurized gas to form a gas seal within the thrust gas bearing.

[0042] (6) A bearing according to any one of (1) to (5) above, wherein the journal bearing has a plurality of grooves defined on the inner surface of the journal bearing at the edge thereof, the grooves having a geometric shape that forms a high pressure region at the edge of the journal bearing.

[0043] (7) A bearing described in any of (1) to (6) above, wherein the converging-diverging orifice comprises at least one inner orifice and at least one outer orifice, and the at least one pressurized gas comprises a process gas supplied through the at least one inner orifice and a clean air gas supplied through the at least one outer orifice, and when the process gas has a higher pressure than the clean air gas, the process gas prevents the clean air gas from leaking into the bearing.

[0044] (8) A bearing according to any one of (1) to (7) above, wherein the converging-diverging orifice comprises at least one inner orifice and at least one outer orifice, and the at least one pressurized gas comprises a process gas supplied through the at least one inner orifice and a clean air gas supplied through the at least one outer orifice, and when the clean air gas has a higher pressure than the process gas, the clean air gas prevents the process gas from leaking from within the bearing.

[0045] (9) A bearing according to any one of (1) to (8) above, wherein the converging-diverging orifice comprises at least one inner orifice, at least one outer orifice, and at least one seal gas orifice located between the at least one inner orifice and the at least one outer orifice, and the at least one pressurized gas comprises a process gas supplied via the at least one inner orifice, a clean air gas supplied via the at least one outer orifice, and a seal gas supplied via the at least one seal gas orifice, and when the seal gas has a higher pressure than the process gas and the clean air gas, the seal gas prevents the process gas from leaking from within the bearing.

[0046] (10) The bearing according to any one of (1) to (9) above, wherein a metal mesh damper is provided on the outer surface of the bearing.

[0047] (11) A turbomachine comprising: a casing having an inlet end and an outlet end opposite the inlet end along its longitudinal axis; a shaft disposed within the casing and extending from the inlet end to the outlet end of the casing; at least one rotor extending radially outward from the shaft; a thrust gas bearing mounted on a journal bearing; and at least one bearing having two or more converging-diverging orifices defined in a surface of at least one of the thrust gas bearing and the journal bearing, the converging-diverging orifices supplying at least one pressurized gas to an interior of the bearing; the rotor housed within the thrust gas bearing; and the shaft at least partially housed within the journal bearing.

[0048] (12) The turbomachine according to (11), wherein the at least one pressurized gas includes a process gas.

[0049] (13) The turbomachine described in (11) or (12) above, wherein the converging-diverging orifices each have a throat, and each orifice is configured to make the flow velocity of the at least one pressurized gas in the throat of the orifice Mach 1 and to make the flow velocity of the at least one pressurized gas passing through the throat supersonic.

[0050] (14) The turbomachine according to any one of (11) to (13) above, wherein the thrust gas bearing comprises a hydrodynamic lifting groove on a surface of the thrust gas bearing, the hydrodynamic lifting groove being configured to generate a gas seal.

[0051] (15) The turbomachine according to any one of (11) to (14) above, wherein the thrust gas bearing is configured to receive the at least one hydrostatic injection of pressurized gas to form a gas seal within the thrust gas bearing.

[0052] (16) A turbomachine according to any one of (11) to (15) above, wherein the edge of the inner surface of the journal bearing has a plurality of grooves defined therein, the grooves having a geometry that forms a high pressure region at the edge of the journal bearing.

[0053] (17) A turbomachine according to any one of (11) to (16), wherein the converging-diverging orifice comprises at least one inner orifice and at least one outer orifice, and the at least one pressurized gas comprises a process gas supplied through the at least one inner orifice and a clean air gas supplied through the at least one outer orifice, and when the process gas has a higher pressure than the clean air gas, the process gas prevents the clean air gas from leaking into the bearing.

[0054] (18) The turbomachine according to any one of (11) to (17), wherein the converging-diverging orifice comprises at least one inner orifice and at least one outer orifice, the at least one pressurized gas comprises a process gas supplied through the at least one inner orifice and a clean air gas supplied through the at least one outer orifice, and when the clean air gas has a higher pressure than the process gas, the clean air gas prevents the process gas from leaking from within the bearing.

[0055] (19) The turbomachine according to any one of (11) to (18), wherein the converging-diverging orifice comprises at least one inner orifice, at least one outer orifice, and at least one seal gas orifice located between the at least one inner orifice and the at least one outer orifice, and the at least one pressurized gas comprises a process gas supplied through the at least one inner orifice, a clean air gas supplied through the at least one outer orifice, and a seal gas supplied through the at least one seal gas orifice, and when the seal gas has a higher pressure than the process gas and the clean air gas, the seal gas prevents the process gas from leaking from within the bearing.

[0056] (20) The turbomachine according to any one of (11) to (19) above, further comprising a metal mesh damper provided on an outer surface of the bearing.

[0057] These and other features and characteristics of the present invention, as well as its method of operation and function of associated elements of construction, and combination of parts and economies of manufacture, will become more apparent from a consideration of the following description and by reference to the accompanying drawings, all of which form a part of this specification, and in which like reference numerals indicate corresponding parts in the various views. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in this specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. [Brief explanation of the drawings]

[0058] [Figure 1] 1 is a perspective, partially cutaway view of a multi-stage centrifugal turbomachine according to an example of the prior art;

[0059] [Figure 2] FIG. 2 is a schematic cross-sectional view of the first stage of the turbomachine shown in FIG.

[0060] [Figure 3] FIG. 1 is a cross-sectional view of a journal bearing and a gas thrust bearing according to an example of the present disclosure.

[0061] [Figure 4] 4A and 4B are cross-sectional views of convergent-divergent orifice configurations in the journal bearing and thrust gas bearing shown in FIG. 3.

[0062] [Figure 5A] 4 is a cross-sectional view showing the air flow direction of the orifices in the journal bearing and thrust gas bearing shown in FIG. 3 having higher clean air pressure.

[0063] [Figure 5B] FIG. 4 is a cross-sectional view showing the air flow direction of the orifices in the journal bearing and thrust gas bearing shown in FIG. 3 with higher process gas pressure.

[0064] [Figure 5C] 4 is a cross-sectional view showing the air flow direction of the orifices in the journal bearing and thrust gas bearing shown in FIG. 3 with higher seal gas pressure. DETAILED DESCRIPTION OF THE INVENTION

[0065] For purposes of the following description, the terms "end," "upper," "lower," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and their derivatives shall refer to the present invention as oriented in the drawings. However, it should be understood that the present invention can contemplate various alternative modifications and step sequences, unless expressly specified to the contrary. It should also be understood that the specific devices and processes illustrated in the accompanying drawings and described in the following specification are merely exemplary implementations or aspects of the present invention. Therefore, specific dimensions and other physical characteristics related to implementations or aspects disclosed herein are not to be considered limiting.

[0066] 3 and 4, a bearing 202 according to one example of the present disclosure is shown. The bearing 202 includes a journal bearing 222 and a thrust gas bearing 220. A plurality of orifices 240 having a converging-diverging shape are defined in one or more surfaces of the bearing 202. One or more surfaces of the bearing 202 are provided with a sealing capability.

[0067] According to one example of the present disclosure, a turbomachine is provided that uses a bearing 202 as illustrated in Figures 3 and 4. The bearing 202 is housed within a casing 204 of the turbomachine, which may be of the same type as or similar to the turbomachine 10 described above with reference to Figures 1 and 2, with one stage of the turbomachine being shown in Figure 3. In addition to the bearing 202, the turbomachine includes a casing 204 having an inlet end and an outlet end opposite the inlet end along its longitudinal axis, as described above with reference to the turbomachine 10 illustrated in Figures 1 and 2, a shaft 210 disposed within the casing 204 and extending from the inlet end to the outlet end of the casing 204, and at least one rotor 208 extending radially outward from the shaft 210. It should be appreciated that the structure of the bearing 202 and the components illustrated in Figure 3 can be utilized in connection with a multi-stage turbomachine, such as a multi-stage centrifugal compressor. Multiple bearings 202 may be spaced apart in multiple stages along the axial length of the shaft 210.

[0068] As shown in FIGS. 3 and 4 , bearing 202 includes a thrust gas bearing 220 mounted to a journal bearing 222. The thrust gas bearing 220 provides support for both axial loads. The thrust gas bearing 220 may be a double-acting thrust gas bearing. The thrust gas bearing 220 may be bonded to the end of the journal bearing 222. According to one implementation, the thrust gas bearing 222 is configured to generate or contain pressurized gas or hydrostatic injection of gas within the thrust gas bearing 220, which may be used to create a dry gas seal within the thrust gas bearing 220. Bearing 202 may be utilized by disposing shaft 210, coupled to rotor 208, within bearing 202 such that shaft 210 is at least partially located or housed within journal bearing 222 and rotor 208 is located or housed within thrust gas bearing 220. According to one example, a casing 204 surrounds bearing 202.

[0069] The static injection of pressurized gas creates a gas film 212 that surrounds the shaft 210 and rotor 208. According to one example, grooves 230 having hydrodynamic lifting features are disposed on the inner surface 224 of the journal bearing 222. The grooves 230 on the journal bearing inner surface 224 improve the load-bearing capacity of the pressurized gas, resulting in less gas being required to maintain the load on the shaft 210 and rotor 208. According to one example, the pressurized gas injected into the bearing 202 is the working fluid of the compressor, known as process gas. According to one example, multiple pressurized gases are injected into the bearing 202 through multiple orifices. These gases may include clean air gas or seal gas.

[0070] As shown in FIG. 4 , the pressurized gas flow 242 may be restricted before reaching the journal bearing inner surface 224. In a typical hydrostatic gas bearing design, restrictors are typically designed to allow approximately 50% of the supply pressure to be available in the gap. According to one example, the restrictor may be designed to allow more than 50% of the supply pressure in the gap. According to one example, the orifice may be designed to allow less than 50% of the supply pressure in the gap. According to one example, the bearing design may utilize an orifice 240 to restrict the gas flow. The orifice 240 may have a converging-diverging design. In a converging-diverging nozzle, the gas flow 242 enters a converging chamber 246 where the cross-sectional area is reduced to a minimum at a throat 244. The size of the throat 244 is designed to choke the flow, e.g., the flow is sonic (Mach number = 1). After passing through the throat 244, the flow may be isentropically expanded in a supersonic diverging cross-sectional area chamber 248. This increases the flow velocity at the orifice exit compared to conventional rectangular or circular orifice shapes.

[0071] Because the dynamic pressure experienced by the rotor 208 surface is proportional to the square of the fluid velocity, maximizing the fluid velocity exiting the orifice maximizes the dynamic pressure of the hydrostatic gas bearing for a given supply gas pressure, and therefore the load capacity. This effect reduces the required gas flow 242 pressure compared to a simple rectangular or circular orifice gas bearing. The orifices 240 can be located at various positions along the surface of the bearing 202. According to one example, multiple orifices 240 can be located at multiple positions along the surface of the bearing 202. According to a particular example, the orifices 240 may be located on one or more surfaces of the thrust gas bearing 220. According to another particular example, the orifices 240 may be located on one or more surfaces of the journal bearing 222. According to another particular example, the orifices 240 may be located on one or more surfaces of both the thrust gas bearing 220 and the journal bearing 222. It should be understood that the orifice 240 may be designed to have alternative geometries different from the converging-diverging design described above, as would be understood by one skilled in the art to be suitable.

[0072] 3 , according to one example of the present disclosure, the inner surface of thrust gas bearing 220 is provided with hydrodynamic lifting grooves 234. Grooves 234 are configured to provide sealing capabilities similar to those of a dry gas seal. The lifting geometry of grooves 234 generates a hydrodynamic lifting force that creates a high pressure gap between thrust gas bearing 220 and rotor 208 at operating speeds. This not only reduces the supply pressure requirements at operating speeds, but also adds sealing capabilities to thrust gas bearing 220.

[0073] According to one example, the sealing capability of the thrust gas bearing 220 can be improved by controlling the pressure ratio of the process gas (the working fluid in the compressor) to the clean air gas at different orifices 240. Also, the sealing capability of the journal bearing 222 can be improved by controlling the pressure ratio of the clean air gas to the process gas at different orifices 240. According to one example, multiple orifices 240 are arranged on the bearing 202 such that one or more orifices 240 are designated as inner orifices and one or more orifices 240 are designated as outer orifices. According to a specific example, the bearing 202 includes one inner orifice, two inner orifices, three inner orifices, or three or more inner orifices. According to another specific example, the bearing 202 includes one outer orifice, two outer orifices, three outer orifices, or three or more outer orifices. An inner orifice refers to an orifice through which the process gas is supplied. The outer orifice refers to an orifice through which clean air, a seal gas, or other gas is supplied. The outer orifice may be located closer to the outer edge of the bearing 202 than the inner orifice. The orifice may be a converging-diverging orifice. The orifice may also have alternative orifice shapes other than a converging-diverging orifice, as would be understood by one skilled in the art to be suitable.

[0074] 3, grooves 232 may be added to the edges of the inner surface 224 of the journal bearing 222 to act as seals and reduce leakage. The grooves 232 on the edges of the journal bearing are positioned to direct the gas so that a high pressure area is created at the edges of the journal bearing 222. This increased pressure at the edges of the bearing acts as a buffer for the supply gas and reduces leakage.

[0075] According to one example, metal mesh damper 206 is disposed between casing 204 and either or both of thrust gas bearing 220 and journal bearing 222 to improve the damping characteristics of bearing 202. Metal mesh damper 206 may provide damping to bearing 202 as it traverses the lateral natural frequency of the rotor-bearing system. Metal mesh damper 206 is housed within casing 204, which also houses bearing 202 and metal mesh damper 206. According to another example, the casing houses bearing 202 without including metal mesh damper 206.

[0076] 5A-5C , an example of controlling the pressure of gas passing through different orifices is shown to enable control of the direction and amount of leakage within a bearing 502. The bearing 502 shown in FIGS. 5A-5C has the same or substantially similar structure as the bearing 202 described above with reference to FIGS. 3 and 4 . Gas may be supplied to the bearing 502 via at least one outer orifice 504 and at least one inner orifice 506. The gas may create a gap between a rotating member 508, such as the rotor 208 or shaft 210 described above with reference to FIGS. 3 and 4 , and the inner surface of the bearing 502. Clean air gas 510 may be supplied to the bearing 502 via the at least one outer orifice 504. Process gas 520 may be supplied into the bearing 502 via the at least one inner orifice 506. As shown in FIG. 5A , the pressure of the clean air gas 510 may be higher than the pressure of the process gas 520. When the pressure of the clean air gas 510 is higher than the pressure of the process gas 520 , the clean air gas 510 can prevent the process gas 520 from leaking from within the bearing 502 to the atmosphere 550 .

[0077] 5B, the pressure of the process gas 520 may be higher than the pressure of the clean air gas 510. If the pressure of the process gas 520 is higher than the pressure of the clean air gas 510, the process gas 520 may prevent the clean air gas 510 from leaking into the turbomachine 560, which could cause all of the clean air gas 510 to leak into the atmosphere 550. According to one example, the higher pressure of the process gas 520 may prevent the clean air gas 510 from leaking further beyond the at least one internal orifice 506 and into the bearing.

[0078] As shown in FIG. 5C , a sealing gas 530 can be injected into the bearing 502 through at least one sealing gas orifice 500. The at least one sealing gas orifice 500 can be disposed between the at least one outboard orifice 504 and the at least one inboard orifice 506. The sealing gas 530 can be a gas other than the clean air gas 510 or the process gas 520. Injecting the sealing gas 530 can be used to control leakage of the process gas 520 and the clean air gas 510. The sealing gas 530 can have a higher pressure than the clean air gas 510 and the process gas 520. When the sealing gas 530 has a higher pressure than the clean air gas 510 and the process gas 520, the sealing gas 530 can prevent the process gas 520 from leaking from the bearing to the atmosphere 550. The sealing gas 530 can also prevent the clean air gas 510 from leaking into the turbomachine 560. According to one example, the higher pressure of the seal gas 530 can prevent the clean air gas 510 from leaking further beyond the at least one seal gas orifice 500 and into the bearing 502. The seal gas 530 can create a barrier between the clean air gas 510 and the process gas 520, keeping the clean air gas 510 and the process gas 520 separated.

[0079] It should be understood that the present invention may assume various alternative modifications and step sequences, unless expressly specified to the contrary. It should also be understood that the specific devices and processes illustrated in the accompanying drawings and described herein are merely exemplary implementations or aspects of the present invention. While the present disclosure has been described in detail for purposes of illustration, based on what are currently considered to be the most practical and preferred implementations or aspects, it should be understood that such details are for that purpose only, and the present invention is not limited to the disclosed implementations or aspects, but on the contrary, is intended to cover modifications and equivalent arrangements within the spirit and scope of the invention. For example, it should be understood that the present invention contemplates that, to the extent possible, one or more features of any implementation or aspect can be combined with one or more features of any other implementation or aspect.

Claims

1. a thrust gas bearing mounted on the journal bearing; two or more converging-diverging orifices defined in a surface of at least one of the thrust gas bearing and the journal bearing; the converging-diverging orifice supplies at least one pressurized gas into the interior of the thrust gas bearing or the journal bearing; the thrust gas bearing is configured to receive hydrostatic injection of the at least one pressurized gas into the thrust gas bearing to form a gas seal within the thrust gas bearing; the converging-diverging orifice comprises at least one inner orifice and at least one outer orifice, the at least one pressurized gas comprises a compressor working fluid supplied through the at least one inner orifice and clean air gas supplied through the at least one outer orifice, the at least one outer orifice being located closer to an outer edge of the thrust gas bearing than the at least one inner orifice; Bearings.

2. the converging-diverging orifices each include a throat, each orifice configured to increase a flow rate of the at least one pressurized gas passing through the throat; 2. The bearing according to claim 1.

3. the thrust gas bearing includes a hydrodynamic lifting groove on an inner surface of the thrust gas bearing, the hydrodynamic lifting groove being configured to create the gas seal; 2. The bearing according to claim 1.

4. an edge of the inner surface of the journal bearing having a plurality of grooves defined therein, the grooves having a shape that creates a region of higher pressure at the edge of the journal bearing than at a portion of the inner surface of the journal bearing other than the edge; 2. The bearing according to claim 1.

5. When the working fluid of the compressor has a higher pressure than the clean air gas, the working fluid of the compressor prevents the clean air gas from flowing beyond the inner orifice.

2. The bearing according to claim 1.

6. When the clean air gas has a higher pressure than the working fluid of the compressor, the clean air gas prevents the working fluid of the compressor from leaking from within the bearing.

2. The bearing according to claim 1.

7. the converging-diverging orifice further comprises at least one seal gas orifice located between the at least one inner orifice and the at least one outer orifice, and the at least one pressurized gas further comprises a seal gas supplied through the at least one seal gas orifice; When the seal gas has a pressure higher than the working fluid of the compressor and the clean air gas, the seal gas prevents the working fluid of the compressor from leaking from inside the bearing.

2. The bearing according to claim 1.

8. A metal mesh damper is provided on the outer surface of the bearing.

2. The bearing according to claim 1.

9. a casing having, along its longitudinal axis, an inlet end and an outlet end opposite the inlet end; a shaft disposed within the casing and extending from the inlet end to the outlet end of the casing; at least one rotor extending radially outward from the shaft; At least one bearing, a thrust gas bearing mounted on the journal bearing; two or more converging-diverging orifices defined in a surface of at least one of the thrust gas bearing and the journal bearing; the converging-diverging orifice supplies at least one pressurized gas into the interior of the thrust gas bearing or the journal bearing; the rotor is housed within the thrust gas bearing; the shaft is at least partially contained within the journal bearing; the thrust gas bearing is configured to receive hydrostatic injection of the at least one pressurized gas into the thrust gas bearing to form a gas seal within the thrust gas bearing; the converging-diverging orifice comprises at least one inner orifice and at least one outer orifice, the at least one pressurized gas comprises a compressor working fluid supplied through the at least one inner orifice and clean air gas supplied through the at least one outer orifice, the at least one outer orifice being located closer to an outer edge of the thrust gas bearing than the at least one inner orifice; Turbomachinery.

10. the converging-diverging orifices each include a throat, each orifice configured to increase a flow rate of the at least one pressurized gas passing through the throat; The turbomachine of claim 9.

11. the thrust gas bearing includes a hydrodynamic lifting groove on an inner surface of the thrust gas bearing, the hydrodynamic lifting groove being configured to create the gas seal; The turbomachine of claim 9.

12. an edge of the inner surface of the journal bearing having a plurality of grooves defined therein, the grooves having a shape that creates a region of higher pressure at the edge of the journal bearing than at a portion of the inner surface of the journal bearing other than the edge; The turbomachine of claim 9.

13. When the working fluid of the compressor has a higher pressure than the clean air gas, the working fluid of the compressor prevents the clean air gas from flowing beyond the inner orifice. The turbomachine of claim 9.

14. When the clean air gas has a higher pressure than the working fluid of the compressor, the clean air gas prevents the working fluid of the compressor from leaking from within the bearing. The turbomachine of claim 9.

15. the converging-diverging orifice further comprises at least one seal gas orifice located between the at least one inner orifice and the at least one outer orifice, and the at least one pressurized gas further comprises a seal gas supplied through the at least one seal gas orifice; When the seal gas has a pressure higher than the working fluid of the compressor and the clean air gas, the seal gas prevents the working fluid of the compressor from leaking from inside the bearing. The turbomachine of claim 9.

16. A metal mesh damper is provided on the outer surface of the bearing. The turbomachine of claim 9.

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