Inducers for cryogenic pumps and related systems and methods

Abstract

The inducer 128 is a hub 136 having an outer side surface 144 extending from a front end 146 to a rear end 148, wherein the outer side surface 144 may include a hub 136 having a first cylindrical front portion 150, a frustoconical intermediate portion 154, and a second cylindrical rear portion 152. The inducer 128 is a main blade 140 extending circumferentially along a first helical path across the front portion 150, the intermediate portion 154, and the rear portion 152, wherein the first helical path may include a main blade 140 having an increasing helical angle. The inducer 128 is a splitter blade 142, each of which may further include a splitter blade 142 circumferentially positioned between two of the main blades 140.

Description

Technical Field

[0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 63 / 468,960, filed May 25, 2023, entitled "MODULAR CRYOGENIC PERMANENT MAGNET ELECTRICAL MOTORS AND GENERATORS FOR SUBMERGED MOTOR PUMPS AND TURBINES AND RELATED SYSTEMS AND METHODS", the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure generally relates to inductors for fluid handling devices, such as submerged motor cryogenic pumps. More specifically, embodiments of the present disclosure may relate to inductors for submerged motor cryogenic pumps that can be used in the liquefaction, transportation, and / or regasification of refrigerated methane liquid, liquefied natural gas, and / or related light hydrocarbon liquids, and / or other fluids and / or liquids such as liquid hydrogen and / or liquid ammonia, as well as related systems and methods.

Background Art

[0003] Pumps may be utilized to control the flow of fluids in various hydraulic processes. For example, some pumps may be used to increase (e.g., boost) the pressure of a hydraulic system, while other pumps may be used to move fluid from one location to another.

[0004] Such devices may be implemented in cryogenic applications including the liquefaction, transport, and regasification of refrigerated liquid methane, liquefied natural gas (LNG), and / or related light hydrocarbon liquids, as well as other fluids such as liquid hydrogen or liquid ammonia. For example, cryogenic submersible pumps may be used in the LNG supply industry, where the pumps are used in the production plant to transfer the product from storage tanks to LNG carriers, from the carriers to storage tanks on the shore, and the product is pumped into pipelines through vaporizers under high pressure. Such cryogenic submersible pumps may benefit from the use of inducers.

[0005] Inducers, also known as pre-swirl devices or booster pumps, are components used in some types of centrifugal pumps to improve performance, particularly under low suction pressure conditions or in situations where cavitation may occur. In some situations, the pump may operate under conditions where the suction pressure is low or where the effective suction head (NPSH) is limited. NPSH is the difference between the total suction head and the vapor pressure of the fluid, and cavitation can occur if the NPSH falls below a certain level. Cavitation is the formation and subsequent collapse of vapor bubbles in the liquid due to low-pressure areas within the pump. When bubbles collapse, they generate shock waves, causing erosion of pump components and a decrease in pump efficiency. Cryogenic liquid-submerged motor pumps can be particularly susceptible to fluid vaporization and cavitation, which may result in pump failure and / or reduced pump performance.

[0006] The inducer is designed to address low suction pressure conditions and the challenges of cavitation. The blades of the inducer may be inclined to induce a rotational component in the inflowing fluid flow. The inducer may increase the fluid pressure and help prevent cavitation by ensuring that the fluid pressure remains higher than the vapor pressure.

[0007] However, existing inducers may have significant problems. For example, inertial forces during startup can cause existing inducers to break and shatter, which can propagate fragments into the pump and cause pump failure. Furthermore, under some relatively low-pressure conditions (e.g., relatively low fluid levels), fluid vaporization may still occur. Existing inducers may not be able to cope with such fluid vaporization, and the vapor may be supplied to the pump, causing cavitation within the pump, reducing pump performance, and / or contributing to pump failure.

[0008] Furthermore, it would be desirable to improve pumps with inducers to adapt to relatively low fluid level conditions within tanks and to facilitate the removal of fluid from the tank to relatively low levels. Fluid that the pump cannot remove from the tank may reduce the effective size of the tank, which may reduce the productivity and / or profitability of the equipment. Similarly, it would be desirable to improve the handling of two-phase fluids (i.e., mixed vapor and liquid fluids). [Overview of the project] [Means for solving the problem]

[0009] In some embodiments, the technology described herein relates to an inducer for a cryogenic pump. The inducer may include a hub, a main blade, and a splitter blade. The hub may have an outer surface extending from a leading end to a trailing end, the outer surface having a first cylindrical leading surface section, a frustoconical intermediate surface section, and a second cylindrical trailing surface section. The main blade may extend radially from the outer surface of the hub to the outer diameter of the inducer and may extend circumferentially along a first helical path across the leading, intermediate, and trailing surfaces, the first helical path having a helical angle that increases from the leading to the trailing surface, defining the main blade angle. The splitter blades may extend radially from the outer surface of the hub to the outer diameter of the inducer, and may extend circumferentially along a second helical path that starts from the intermediate surface and extends across the intermediate and rear surfaces of the outer surface of the hub, the second helical path having a helical angle that increases from the front to the rear, defining the splitter blade angle, and each of the splitter blades is circumferentially located between two of the main blades.

[0010] In some embodiments, the technology described herein relates to an inducer, wherein the diameter of the rear portion of the hub is at least about 75% of the outer diameter of the inducer.

[0011] In some embodiments, the technology described herein relates to an inducer, where the diameter of the rear surface of the hub is approximately 78% of the outer diameter of the inducer.

[0012] In some embodiments, the technology described herein relates to an inducer, wherein the diameter of the front portion of the hub is less than approximately 33% of the outer diameter of the inducer.

[0013] In some embodiments, the technology described herein relates to an inducer, where the diameter of the front portion of the hub is approximately 30% of the outer diameter of the inducer.

[0014] In some embodiments, the technology described herein relates to an inducer, each of which has a swept leading edge, defined by a radial blade length that gradually increases over a sweep angle of at least 40° from the front tip located on the front of the hub to the rear tip located on the outer diameter of the inducer.

[0015] In some embodiments, the technology described herein relates to an inducer, wherein the leading edge of each splitter blade is at least about 30% closer to the circumferentially trailing main blade than to the circumferentially leading main blade.

[0016] In some embodiments, the technology described herein relates to an inducer, wherein the trailing edge of each splitter blade is at approximately equal distances from the circumferentially trailing main blade and the circumferentially leading main blade.

[0017] In some embodiments, the technology described herein relates to an inducer, wherein the front portion of the hub is greater than 5% of the axial length of the inducer, and the rear portion of the hub is greater than 5% of the axial length of the inducer.

[0018] In some embodiments, the technology described herein relates to an inducer, wherein each of the main blades and each of the splitter blades includes an arched outer surface that defines the outer diameter of the inducer.

[0019] In some embodiments, the technology described herein relates to an inducer in which one or more arched outer surfaces of the main blades have a wrap angle of approximately 180°.

[0020] In some embodiments, the technology described herein relates to an inducer, wherein the principal blade angle at each of the one or more principal blade positions on the outer diameter of the inducer is smaller than the principal blade angle on the outer side surface of the hub corresponding to the same axial position.

[0021] In some embodiments, the technology described herein relates to an inducer, wherein the angle of one or more of the main blades at the leading edge position on the outer side surface of the hub is less than approximately 25°.

[0022] In some embodiments, the technology described herein relates to an inducer, wherein the angle of one or more of the main blades at the trailing edge position on the outer side surface of the hub is greater than approximately 27°.

[0023] In some embodiments, the technology described herein relates to an inducer, wherein the angle of one or more of the main blades at the leading edge position on the outer diameter of the inducer is less than approximately 8.5°.

[0024] In some embodiments, the technology described herein relates to an inducer, wherein the angle of one or more of the main blades at the trailing edge position on the outer diameter of the inducer is greater than approximately 20°.

[0025] In some aspects, the technology described herein relates to a pump for pumping cryogenic fluids. The pump may include a fluid inlet, a fluid outlet, a motor, a pump stage, an inducer positioned between the fluid inlet and the pump stage, and a drive shaft coupling the motor to the pump stage and the inducer. The inducer may include a hub, a main blade, and a splitter blade. The hub may have an outer side surface extending from a front end to a rear end, and the outer side surface may have a front portion having a first cylindrical shape, an intermediate portion having a frustoconical shape, and a rear portion having a second cylindrical shape. The main blade may extend radially from the outer side surface of the hub to the outer diameter of the inducer and may extend circumferentially along a first helical path over the front portion, the intermediate portion, and the rear portion, the first helical path having a helical angle increasing from the front portion to the rear portion that defines a main blade angle. The splitter blade may extend radially from the outer side surface of the hub to the outer diameter of the inducer and may extend circumferentially along a second helical path starting from the intermediate portion and extending over the intermediate portion and the rear portion of the outer side surface of the hub, the second helical path having a helical angle increasing from the front portion to the rear portion that defines a splitter blade angle, and each of the splitter blades is circumferentially positioned between two of the main blades.

[0026] In some aspects, the technology described herein relates to a pump further including inducer guide vanes positioned between the inducer and the pump stage.

[0027] In some aspects, the technology described herein relates to a method of inducing flow in a cryogenic pump, the method including rotating an inducer to draw fluid through a fluid inlet by the inducer and guide the fluid to inducer guide vanes, and providing the fluid to a first pump stage of a cryogenic pump at a pressure greater than a head about 100 feet higher than the fluid inlet and with a subcooling of more than 3 Kelvin relative to the fluid temperature at the fluid inlet.

[0028] In some embodiments, the techniques described herein further relate to a method that includes providing fluid to a first pump stage of a cryogenic pump at a pressure greater than a head of about 125 feet higher than a fluid inlet and at a subcooling of more than 4 degrees Kelvin relative to a fluid temperature at the fluid inlet.

[0029] In some embodiments, the techniques described herein further relate to a method that includes providing fluid to a first pump stage of a cryogenic pump at a pressure greater than a head of about 140 feet higher than a fluid inlet and at a subcooling of more than 5 degrees Kelvin relative to a fluid temperature at the fluid inlet.

[0030] In some embodiments, the techniques described herein further relate to a method that further includes recondensing a fluid having a vapor fraction greater than 18% at an inlet and delivering the fluid in a subcooled liquid state to a first pump stage.

[0031] In some embodiments, the technology described herein relates to a method for manufacturing a cryogenic pump. The method may include coupling a motor to a drive shaft, coupling a pump stage to a drive shaft, and coupling an inducer to a drive shaft. The inducer may include a hub, main blades, and splitter blades. The hub may have an outer surface extending from a front end to a rear end, the outer surface having a front portion having a first cylindrical shape, an intermediate portion having a frustoconical shape, and a rear portion having a second cylindrical shape. The main blade may extend radially from the outer surface of the hub to the outer diameter of the inducer and may extend circumferentially along a first helical path across the front, intermediate, and rear portions, the first helical path having a helical angle that increases from the front to the rear portion, defining the main blade angle. The splitter blades may extend radially from the outer surface of the hub to the outer diameter of the inducer, and may extend circumferentially along a second helical path that starts from the intermediate surface and extends across the intermediate and rear surfaces of the outer surface of the hub, the second helical path having a helical angle that increases from the front to the rear, defining the splitter blade angle, and each of the splitter blades is circumferentially located between two of the main blades.

[0032] This specification concludes with claims that specifically identify and explicitly claim embodiments of the present disclosure, although various features and advantages of embodiments of the present disclosure can be more readily identified from the following description of exemplary embodiments of the present disclosure when read in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0033] [Figure 1] This is an elevation cross-sectional view of a modular liquid-submerged motor cryogenic pump according to one embodiment of the present disclosure. [Figure 2] This is an isometric view of an inducer according to one embodiment of the present disclosure. [Figure 3] Figure 2 is an elevation cross-sectional view of the inducer. [Figure 4]Figure 2 is an isometric end view of the front end of the inducer. [Figure 5] Figure 2 is an isometric end view of the rear end of the inducer. [Figure 6] This is a cross-sectional view of an inducer guide vane according to one embodiment of the present disclosure. [Figure 7] Figure 6 is an isometric view of the central portion of the inducer guide vane. [Modes for carrying out the invention]

[0034] The illustrations presented herein are not intended to be actual diagrams of any particular fluid exchanger or its components, but are merely idealized representations employed to illustrate exemplary embodiments. The drawings are not necessarily to the same scale. Elements common to both drawings may retain the same numerical notation.

[0035] The terms “first,” “second,” “top,” and “bottom” used herein are generally used for clarity and convenience in understanding this disclosure and the accompanying drawings, and do not imply, or rely on, any particular preference, orientation, or order unless the context otherwise clearly indicates.

[0036] As used herein, the term "and / or" means any combination of one or more of the related enumerated items, including any such combination.

[0037] As used herein, the terms “vertical” and “lateral” refer to the orientations shown in the figures.

[0038] As used herein, the terms “substantially” or “about” with respect to a given parameter mean, and include, the degree to which a person skilled in the art would understand that a given parameter, characteristic, or condition is met with a low degree of variance, such as within acceptable manufacturing tolerances. For example, a substantially met parameter may be met at least 90%, at least 95%, at least 99%, or even 100%.

[0039] As used herein, the term “fluid” may mean, or include, any type and composition of fluid. The fluid may be in liquid form, gaseous form, or a combination thereof, and in some cases may include some solid material. In some embodiments, the fluid may change between liquid and gaseous forms during a cooling or heating process as described herein. In some embodiments, the term “fluid” may include gases, liquids, and / or pumpable mixtures of liquids and solids.

[0040] Figure 1 is an elevation cross-sectional view of a modular submersible motor cryogenic pump 100 according to one embodiment of the present disclosure, comprising a motor module 102 and a hydraulic module 104. Since the modular submersible motor cryogenic pump 100 may be operated under low-temperature conditions, it may be provided with all the components suitable for operation within an operating temperature range of approximately 75K to approximately 200K. Furthermore, the modular submersible motor cryogenic pump 100 may be designed to provide leak-proof containment at operating pressures between approximately 1 bar absolute pressure (barA) and approximately 160 barA.

[0041] The motor module 102 may include a motor 106 located within a motor housing 108. The motor 106 may include a rotor 110 (e.g., a permanent magnet rotor) which can be coupled to a drive shaft 112 and a stator 114 surrounding the rotor 110. In some embodiments, the motor 106 may be a variable-speed synchronous motor. In further embodiments, the motor may be configured to rotate relatively faster than a conventional motor, for example, the motor may be configured to rotate at speeds from about 2,000 revolutions per minute (RPM) to 10,000 RPM, and at speeds greater than 4,000 RPM, greater than 5,000 RPM, greater than 6,000 RPM, and / or greater than 7,000 RPM.

[0042] The hydraulic module 104 may include one or more centrifugal pumps or pump stages 116 (e.g., five pump stages 116 as shown) located within the pump housing 118 and coupled to the drive shaft 112. The pump housing 118 may include an end plate 120 having a nozzle 122 defining a fluid inlet 124 to a modular submersible motor cryogenic pump 100 at a first end, and a hydraulic manifold 126 at a second end. An inducer 128 (described in more detail herein with reference to Figures 2 to 5) may be located within the nozzle 122 between the fluid inlet 124 and the first pump stages 116 and may be coupled to one end of the drive shaft 112. For example, the inducer 128 may be coupled to the drive shaft 112 via one or more of the following: interference fit (e.g., friction fit or close bore fit), interlocking spline, keying coupling (e.g., key, key seat, and keyway), collet, and / or fasteners (e.g., nut, bolt, and / or retaining ring). Furthermore, inducer guide vanes 132 (described in more detail herein with reference to Figures 6 and 7) may be located between the inducer 128 and the first pump stage 116, and the inducer guide vanes 132 may be used to recover the kinetic energy of the fluid leaving the inducer to further increase the fluid pressure (i.e., head) at the inlet to the first pump stage 116.

[0043] The motor module 102 may be coupled to the hydraulic module 104, and a fluid passage (e.g., pipe 134) may be positioned to guide fluid from the hydraulic manifold 126 of the hydraulic module 104 to a hydraulic manifold 138 located at the upper end of the motor module 102. The hydraulic manifold 138 may include a fluid outlet 139 for guiding fluid out of the modular submersible motor cryogenic pump 100. Furthermore, internal fluid passages may guide a portion of the fluid pumped from the hydraulic module 104 to the motor module 102 to regulate the temperature of components within the motor module 102, such as the motor 106 and bearings, during operation.

[0044] Figure 1 shows a liquid-submerged motor cryogenic pump, but in other embodiments, the inducer according to this disclosure may be used in other pumps or fluid handling devices.

[0045] Figure 2 is an isometric view of an inducer 128 that may be used in conjunction with the modular submersible motor cryogenic pump 100 of Figure 1. The inducer may include a hub 136, and main blades 140 and splitter blades 142 extending radially from the outer side surface 144 of the hub 136 (relative to the axis of rotation 145). For example, inducer 128 may include three main blades 140 and three splitter blades 142.

[0046] Figure 3 is an elevation cross-sectional view of the inducer 128 of Figure 2. As shown in Figure 3, the outer side surface 144 of the hub 136 may extend from the front end 146 to the rear end 148 of the inducer 128. The outer side surface 144 of the hub 136 may have a front portion 150 adjacent to the front end 146, having a first substantially cylindrical shape, and a rear portion 152 adjacent to the rear end 148, having a second substantially cylindrical shape. Furthermore, the outer side surface 144 of the hub 136 may have an intermediate surface portion 154 located between the front portion 150 and the rear portion 152, having a frustoconical shape. For example, the width (e.g., diameter) of the hub 136 may gradually increase between the front portion 150 and the rear portion 152.

[0047] The rear portion 152 of the hub 136 may have a significantly larger outer diameter than the front portion 150. In some embodiments, the diameter of the rear portion 152 of the hub 136 may be at least about 75% of the outer diameter of the inducer 128. For example, the diameter of the rear portion 152 of the hub 136 may be about 78% of the outer diameter of the inducer 128. On the other hand, the outer diameter of the front portion 150 of the hub 136 may be less than about 33% of the outer diameter of the inducer 128. For example, the diameter of the front portion 150 of the hub 136 may be about 30% of the outer diameter of the inducer 128.

[0048] The front portion 150 of the hub 136 may extend along at least 5%, at least 6%, at least 7%, at least 8%, and / or at least 9% of the axial length of the hub 136 (i.e., from the front end 146 to the rear end 148). For example, the front portion 150 of the hub 136 may extend along about 10% of the axial length of the hub 136. Similarly, the rear portion 152 of the hub 136 may extend along at least 5%, at least 6%, at least 7%, at least 8%, and / or at least 9% of the axial length of the hub 136. For example, the front portion 150 of the hub 136 may extend along about 10% of the axial length of the hub 136.

[0049] The transitions between the surface portions of the outer side surface 144 of the hub 136 may be filleted. For example, a first fillet may be located between the front end 146 and the front portion 150, a second fillet may be located between the front portion 150 and the intermediate surface portion 154, a third fillet may be located between the intermediate surface portion 154 and the rear surface portion 152, and a fourth fillet may be located between the rear surface portion 152 and the rear end 148.

[0050] The main blade 140 may extend radially from the outer side surface 144 of the hub 136 toward or to the outer diameter of the inducer 128. The outer diameter of the inducer 128 is sized to correspond to the inner diameter of the nozzle 122 of the pump housing 118 such that the outer diameter of the inducer 128 is adjacent to the inner diameter of the nozzle 122, with a relatively small gap between them. The main blade 140 may further extend circumferentially along the first helical path across the front portion 150, the middle portion 154, and the rear portion 152 of the outer side surface 144 of the hub 136.

[0051] Unlike typical screws (i.e., Archimedean screws) which may have one or more blades or threads following a helical path at a constant helical angle, the helical angle of the first helical path of the inducer 128 may not be constant and may vary. For example, the first helical path may have a helical angle that increases from the front portion 150 to the rear portion 152, defining the main blade angle. Thus, the spacing between the main blades 140 may increase from the front portion 150 to the rear portion 152, and the blade angle of the main blades 140 may become larger (e.g., steeper) as the main blades 140 extend from the front portion 150 to the rear portion 152. In some embodiments, the helical angle along the first helical path may increase (e.g., linearly) as the main blades 140 extend from the front edge 158 to the rear edge 162 of the main blades 140 (see Figure 2).

[0052] For example, referring again to Figure 2, the angle of one or more of the main blades 140 at the leading edge 158 position on the outer side surface 144 of the hub 136 (i.e., the angle of the main blades 140 measured tangentially to a reference plane oriented perpendicular to the axis of rotation of the inducer 128) may be oriented to a first angle, and the angle of one or more of the main blades 140 may increase (e.g., gradually) as the main blades 140 extend to the trailing edge 162 position on the outer side surface 144 of the hub 136.

[0053] In some embodiments, the angle of one or more of the main blades 140 at the leading edge 158 position on the outer side surface 144 of the hub 136 may be less than about 27°, less than about 26°, and / or less than about 25°. In some embodiments, the angle of one or more of the main blades 140 at the leading edge 158 position on the outer side surface 144 of the hub 136 may be between about 22.5° and about 26.5°, between about 23° and about 26°, between about 23.5° and about 25.5°, and / or between about 24° and about 25°.

[0054] In some embodiments, the angle of one or more of the main blades 140 at the trailing edge 162 position on the outer side surface 144 of the hub 136 may be greater than about 27°, greater than about 28°, and / or greater than about 29°. In some embodiments, the angle of one or more of the main blades 140 at the trailing edge 162 position on the outer side surface 144 of the hub 136 may be between about 26° and about 30°, between about 26.5° and about 29.5°, between about 29° and about 27°, and / or between about 28° and about 27.5°.

[0055] For example, in some embodiments, the helical angle (i.e., main blade angle) of the first helical path may begin at approximately 24.6° at the leading edge 158, and the helical angle may increase linearly along the first helical path, ending at approximately 27.8° at the trailing edge 162.

[0056] Each of the main blades 140 may include an arched outer surface 166 that can be positioned in close proximity to a shroud (e.g., a nozzle 122 shown in Figure 1). The arched outer surface 166 may define the outer diameter of the inducer 128 (e.g., the outermost diameter of the inducer 128). One or more arched outer surface 166 of the main blades 140 may have a full turn angle greater than 150° (i.e., a circumferential range around the hub 136), and each of the main blades 140 may have a full turn angle greater than 180° in the midspan (i.e., a span extending tangentially along the radial middle). In some embodiments, one or more arched outer surface 166 of the main blades 140 may have a full turn angle of about 180° (i.e., a circumferential range around the hub 136), and each of the main blades 140 may have a full turn angle of about 217° in the midspan (i.e., a span extending tangentially along the radial middle).

[0057] The angles of one or more of the main blades 140 at the outer diameter of the inducer 128 (i.e., at the arched outer surface 166) may be smaller than the angles of the main blades at the outer surface 144 of the hub 130 corresponding to the same axial position. That is, the main blade angles may gradually decrease as the main blades 140 extend radially outward from the hub 130 to the arched outer surface 166.

[0058] As described above, the angles of one or more of the main blades 140 may also vary (e.g., gradually increase) between the leading edge 158 and the trailing edge 162 in the outer diameter of the inducer 128 (i.e., in the arched outer surface 166). That is, the main blade angles may gradually increase as the main blade 140 extends axially along the outer diameter of the inducer 128 (i.e., in the arched outer surface 166) between the entrance, i.e., the leading edge 158 and the exit, i.e., the trailing edge 162.

[0059] In some embodiments, the angle of one or more of the main blades 140 at the leading edge 158 position on the outer diameter of the inducer 128 (i.e., on the arched outer side surface 166) may be less than about 11°, less than about 10°, and / or less than about 9°. In some embodiments, the angle of one or more of the main blades 140 at the leading edge 158 position on the outer diameter of the inducer 128 (i.e., on the arched outer side surface 166) may be between about 6° and about 10°, between about 7° and about 9°, and / or between about 7.5° and about 8.5°.

[0060] In some embodiments, the angle of one or more of the main blades 140 at the trailing edge 162 position on the outer diameter of the inducer 128 (i.e., on the arched outer side surface 166) may be greater than about 18°, greater than about 19°, and / or greater than about 20°. In some embodiments, the angle of one or more of the main blades 140 at the trailing edge 162 position on the outer diameter of the inducer 128 (i.e., on the arched outer side surface 166) may be between about 18° and about 22°, between about 19° and about 21.5°, and / or between about 19.5° and about 20°.

[0061] For example, the angle of one or more of the main blades 140 at the leading edge 158 position on the outer diameter of the inducer 128 (i.e., on the arched outer side surface 166) may be less than approximately 8.5°, and the angle of one or more of the main blades 140 at the trailing edge 162 position on the outer diameter of the inducer 128 may be greater than approximately 20°. In some embodiments, the angle of one or more of the main blades 140 at the leading edge 158 position on the outer diameter of the inducer 128 (i.e., on the arched outer side surface 166) may be approximately 8°, and the angle of one or more of the main blades 140 at the trailing edge 162 position on the outer diameter of the inducer 128 may be greater than approximately 20.5°.

[0062] The main blades 140 may be tapered in close proximity to the front end 146 of the inducer 128, but the majority of one or more of the main blades 140 may have a substantially constant thickness. The tapering of the main blades 140 at the front end 146 may be provided by molding alone, or mainly on the low-pressure side of the front end of the main blades 140 (i.e., the side facing the front end 146 of the inducer 128).

[0063] Figure 4 is an isometric end view of the front end 146 of the inducer 128 in Figure 2. As can be seen in Figure 4, each of the main blades 140 may have a curved front edge 158. The curved front edge 158 is defined by a gradually increasing radial blade length from the front tip 172 of the front edge 158 located on the front surface 150 of the hub 136 (see Figure 3), where the front edge 158 contacts the hub 136, to the rear end 174 of the front edge 158 located on the outer diameter of the inducer 128, where the front edge 158 contacts the arched outer surface 166 (see Figure 2). In other words, the main blade 140 does not simply extend linearly radially from the hub to the outer diameter of the inducer at the front tip 172, but rather gradually extends radially outward from the front tip 172 to the rear end 174 to define the curved front edge 158. Therefore, the leading edge 158 may curve backward over the circumferential distance without defining a relatively sharp angle protruding radially at the leading end of the main blade 140. The curved leading edge 158 may have a full-wound angle greater than approximately 40°. In some embodiments, the curved leading edge 158 may have a full-wound angle greater than approximately 50°. In further embodiments, the curved leading edge 158 may have a full-wound angle greater than approximately 60°. Furthermore, one or more leading edges 158 of the main blade 140 may be curved bullnose edges, and the trailing edge 162 (see Figure 2) may be a relatively sharp bevel edge.

[0064] Referring again to Figures 2 and 3, the splitter blade 142 may extend radially from the outer surface 144 of the hub 136 to the outer diameter of the inducer 128, and may extend circumferentially along a second helical path that starts from the intermediate surface 154 and extends across the intermediate surface 154 and rear surface 152 of the outer surface 144 of the hub 136. The second helical path may have a helical angle that increases from the intermediate surface 154 to the rear surface 152, defining the splitter blade angle. Each of the splitter blades 142 may be circumferentially positioned around the hub 130 between two of the main blades 140. In some embodiments, the helical angle along the second helical path may increase (e.g., linearly) from the leading edge 180 of the splitter blade 142 to the trailing edge 182 of the splitter blade 142.

[0065] The positioning of the splitter blades 142 between each main blade 140 may vary as the splitter blades 142 extend between the leading edge 180 and the trailing edge 182. For example, one or more leading edges 180 of the splitter blades 142 may be positioned relatively closer (e.g., at least about 30% closer) to the circumferentially trailing main blades 140 than to the circumferentially leading main blades 140. Furthermore, one or more trailing edges 182 of the splitter blades 142 may be positioned at approximately equal distances from the circumferentially trailing main blades 140 and the circumferentially leading main blades 140.

[0066] Like the main blade 140, each splitter blade 142 may include an arched outer side surface 184 having substantially the same diameter as one or more arched outer side surfaces 166 of the main blade 140 that define the outer diameter of the inducer 128. Also like the main blade 140, one or more leading edges 180 of the splitter blade 142 may be curved bullnose edges, and trailing edges 182 may be relatively sharp bevel edges. The leading edges 180 of the splitter blade 142 may also be curved, but may be curved over a smaller full turn angle relative to the leading edge 146 of the main blade 140. For example, the leading edges 180 of the splitter blade 142 may have a full turn angle of less than approximately 40°. Furthermore, the blade angles at each of the one or more positions of the splitter blades 142 on the outer diameter of the inducer 128 (i.e., on the arched outer surface 184) may be smaller than the blade angles on the outer surface 144 of the hub 130 corresponding to the same axial position.

[0067] Figure 5 is an isometric end view of the rear end of the inducer 128 in Figure 2. As shown, the rear ends 148 of the main blade 140 and the rear ends 174 of the splitter blade 142 may be evenly spaced around the circumference of the hub 130 at the rear end of the inducer 128. Thus, the rear ends 148 of the main blade 140 may be evenly spaced from each other, and may also be evenly spaced from each of the adjacent rear ends 174 of the splitter blade 142.

[0068] In some embodiments, the inducer 128 may be machined from a solid billet of a material such as bronze, brass, steel, or aluminum using a computer numerical control (CNC) mill and / or lathe. In further embodiments, the inducer 128 may be machined from multiple solid billets of a material such as bronze, brass, steel, and / or aluminum using a computer numerical control (CNC) mill and / or lathe, and may be assembled by brazing and / or welding. In yet another embodiment, the inducer 128 may be cast from a molten material such as bronze, brass, steel, or aluminum by investment casting or sand casting.

[0069] Figure 6 is a cross-sectional view of an inducer guide vane 132 of a modular submersible motor cryogenic pump 100 according to one embodiment of the present disclosure. The inducer guide vane 132 may be located between the inducer 128 and the first pump stage 116 (see Figure 1). The inducer guide vane 132 may include a hub 186 having a central opening 188 for allowing a drive shaft 112 to pass through it, and a plurality of vanes 190 extending from the hub 186. Furthermore, the inducer guide vane 132 may include an outer annular guide 192 surrounding the hub 186 and the plurality of vanes 190, the plurality of vanes 190 extending from the hub 186 to the outer annular guide 192 to form a plurality of fluid passages between the hub 186 and the outer annular guide 192. The outer annular guide 192 may have an annular tapered inner surface having a front diameter greater than the rear diameter.

[0070] Figure 7 is an isometric view of the central portion 198 of the inducer guide vane 132, showing the hub 186 and the multiple vanes 190 without showing the surrounding outer annular guide 192 (see Figure 6). The outer diameter of the front end of the hub 186 of the inducer guide vane 132 may be determined to be the same size as the outer diameter of the rear end of the hub 130 of the inducer 128, and the outer diameter of the rear end of the hub 186 may be smaller than the outer diameter of the front end of the hub 186.

[0071] The multiple blades 190 of the inducer guide blade 132 may extend along a helical path on the outer side surface of the hub 186, and the helical path may extend in the circumferential direction opposite to the helical path of the main blade 140 of the inducer 128. The helical path may have a helical angle that defines the blade angle, increasing from the front end to the rear end of the multiple blades 190. In some embodiments, the helical angle along the helical path may increase linearly from the front edge 194 of one or more of the multiple blades 190 to the rear edge 196 of one or more of the multiple blades 190.

[0072] In some embodiments, the angle of one or more of the multiple blades 190 (i.e., the angle of the blade 190 measured tangentially to a reference plane perpendicular to the axis of rotation of the drive shaft 112 within the inducer guide blade 132) may increase between the leading edge 194 and the trailing edge 196. In some embodiments, the angle of one or more of the multiple blades 190 may increase between the hub 186 and a radially outward position close to the outer annular guide 192.

[0073] In some embodiments, the blade angles of one or more of the blades 190 at the leading edge 194 position of the hub 186 may be between approximately 36° and approximately 40°, between approximately 37° and approximately 39°, and / or between approximately 37.5° and approximately 38.5°, and the blade angles of one or more of the multiple blades 190 at the trailing edge 196 position of the hub 186 may be between approximately 85° and approximately 95°, between approximately 88° and approximately 92°, and / or between approximately 89° and approximately 91°. For example, the blade angle may start at approximately 38° at the leading edge 194 position of the hub 186, and the blade angle may increase along a helical path (e.g., linearly) to end at approximately 90° at the trailing edge 196 position of the hub 186.

[0074] In some embodiments, the blade angles of one or more of the blades 190 at the leading edge 194 position of the outer annular guide 192 may be between approximately 27° and approximately 33°, between approximately 28° and approximately 32°, and / or between approximately 29° and approximately 31°, and the blade angles of one or more of the multiple blades 190 at the trailing edge 196 position of the outer annular guide 192 may be between approximately 85° and approximately 95°, between approximately 88° and approximately 92°, and / or between approximately 89° and approximately 91°. For example, the blade angle may begin at approximately 30.5° at the leading edge 194 position of the outer annular guide 192, and the blade angle may increase linearly along the helical path to end at approximately 90° at the trailing edge 196 position of the outer annular guide 192.

[0075] In some embodiments, one or more of the multiple blades 190 may have a full winding angle (i.e., circumferential range) of approximately 51°. The blade angle at each position of one or more of the multiple blades 190 in the outer annular guide 192 may be smaller than the blade angle at the hub 186 corresponding to the same axial position at the front end of the inducer guide blade 132. The blade angle of one or more of the multiple blades 190 at the rear end may be substantially the same as the angle at the hub 186 as the angle at the outer annular guide 192.

[0076] In some embodiments, the inducer guide vane 132 may be machined from a solid billet of a material such as bronze, brass, steel, or aluminum using a computer numerical control (CNC) mill and / or lathe. In further embodiments, the inducer guide vane 132 may be machined from multiple solid billets of a material such as bronze, brass, steel, and / or aluminum using a computer numerical control (CNC) mill and / or lathe, and may be assembled by brazing and / or welding. In yet another embodiment, the inducer guide vane 132 may be cast from a molten material such as bronze, brass, steel, or aluminum by investment casting or sand casting.

[0077] In view of the above, and referring again to Figure 1, the modular liquid-submerged motor cryogenic pump 100 may be manufactured by coupling a appropriately sized motor module 102 with an appropriately sized hydraulic module 104 and inducer 128. The motor 106 of the motor module 102 and the pump stage 116 of the hydraulic module 104 may be coupled to the drive shaft 112 so that the motor 106 can power the pump stage 116. The inducer 128 may be coupled to the end of the drive shaft 112 so that the inducer 128 can also be rotated by the motor 106. Furthermore, the inducer guide vane 132 may be positioned between the inducer 128 and the first pump stage 116 by extending the drive shaft 112 through the central opening 188 of the inducer guide vane 132.

[0078] During operation, the modular submersible motor cryogenic pump 100 may be located within a cryogenic fluid tank (not shown) and may be submerged in cryogenic fluid with the fluid inlet 124 located close to the bottom of the cryogenic fluid tank. Power may be supplied to a motor 106 capable of rotating the stator 114, thereby rotating a drive shaft 112 coupled to the stator 114. The drive shaft 112 may rotate the pump stage 116 and inducer 128 to initiate the pumping of cryogenic fluid by the modular submersible motor cryogenic pump 100.

[0079] If significant power is supplied to the motor 106 at startup (for example, if the motor 106 is directly connected to the line power), the rotation of the stator 114 may accelerate relatively quickly, thereby accelerating the pump stage 116 and inducer 128 relatively quickly. The rapid acceleration of the inducer 128 and the fluid inertia may generate significant forces on the inducer 128, particularly on the leading edge 158 of the main blade 140. However, the curvature of the leading edge 158 may reduce and / or more effectively distribute the forces acting on the leading edge 158 and / or provide sufficient structural support for the main blade 140 at the leading edge 158, in order to prevent the main blade 140 from being crushed and / or broken in situations where inducers having blades without such a curved leading edge may be crushed and / or broken.

[0080] In some embodiments, the motor 106 may be a variable-speed synchronous motor driven by a variable-frequency drive. Thus, the rotational acceleration of the motor 106 may be controlled and reduced during startup to further reduce the possibility of crushing and / or damage to the main blade 140 during startup of the modular submersible motor cryogenic pump 100.

[0081] The rotation of the inducer 128 may draw the fluid into the modular submersible motor cryogenic pump 100, compress and accelerate the fluid, and guide the fluid to the inducer guide vanes 132 to provide the fluid to the first pump stage 116 at high pressure, thereby preventing and / or reducing vaporization and / or cavitation within the first pump stage 116. Furthermore, the significant increase in the diameter of the rear portion 152 of the hub 136 relative to the diameter of the front portion 150 may significantly reduce the size of the passage formed between the main blade 140 and the surrounding enclosure plate as the fluid moves from the front end 146 to the rear end 148 of the hub 136. This significant reduction in fluid passage size may significantly increase the fluid velocity and / or pressure as the fluid passes through the passage. Furthermore, the shapes of the main blade 140 and splitter blade 142, such as the blade angle increasing from the leading edge 158 to the trailing edge 162 and the blade angle at the hub 136 relative to the blade angle at the arched outer side surface 166, may significantly accelerate and / or pressurize the fluid due to the pressure difference created between the upper and lower parts of the main blade 140 and splitter blade 142, and due to centrifugal force.

[0082] The fluid exiting the inducer 128 may be guided to the inducer guide vane 132. The fluid exiting the inducer 128 may have a significant tangential velocity when it enters the inducer guide vane 132. The multiple vanes 190 of the inducer guide vane 132 may re-guide the fluid flow and change the direction of the tangential component of the fluid flow so as to guide the flow substantially axially. Thus, the inducer guide vane 132 may convert the tangential velocity of the fluid flow into head (i.e., pressure) and may further compress the fluid after it has exited the inducer 128 and before it enters the first pump stage 116.

[0083] Pump stages 116 may pump fluid through them, increasing the fluid pressure and / or velocity at each pump stage 116. The fluid may then be guided to a hydraulic manifold 126, through a pipe 134, to a hydraulic manifold 138, and out of the modular submersible motor cryogenic pump 100 via a fluid outlet 139. A portion of the fluid may flow into a motor module 102 to cool components such as the motor 106.

[0084] During operation, the inducer 128 may perform significantly better than the previous inducer. In some embodiments, the inducer 128 may have a suction specific velocity greater than 100,000, greater than 200,000, and / or greater than 300,000. In some embodiments, the inducer 128, together with the inducer guide vanes 132, may generate a head of more than 100 feet, a head of more than 125 feet, and / or a head of more than 140 feet at the inlet of the first pump stage 116. For example, the inducer 128, through the inducer guide vanes 132, may generate a head of about 150 feet at the inlet of the first pump stage 116. Furthermore, the inducer 128 may induce significant supercooling, and through the inducer guide vanes 132, may induce supercooling of more than 3 Kelvin, more than 4 Kelvin, and / or more than 5 Kelvin at the inlet of the first pump stage 116. For example, the inducer 128 may induce supercooling of about 6 Kelvin at the inlet of the first pump stage 116 through the inducer guide vanes 132. Thus, the inducer 128 may be capable of recondensing a fluid having a significant vapor fraction at the fluid inlet 124 of the modular liquid-submerged motor cryogenic pump 100 and delivering it to the inlet of the first pump stage 116 in a supercooled liquid state through the inducer guide vanes 132. For example, the inducer 128 may be capable of recondensing a fluid having a vapor fraction of more than 10%, more than 15%, more than 18%, and / or more than 20% at the fluid inlet 124 of the modular submersible motor cryogenic pump 100, and delivering it in a supercooled liquid state to the inlet of the first pump stage 116 through the inducer guide vane 132. In view of the above, the inducer 128 may also enable the modular submersible motor cryogenic pump 100 to remove a significantly larger amount of fluid from the tank than existing pumps, which may increase the productivity and / or profitability of the equipment.

[0085] For example, the inducer 128 may guide fluid to the inducer guide vane 132 to supply fluid to the first pump stage 116 of a supercooled cryogenic pump 100 at a pressure greater than a head approximately 100 feet higher than the fluid inlet 124 and a fluid temperature greater than 3 Kelvin at the fluid inlet 124. In another example, the inducer 128 may guide fluid to the inducer guide vane 132 to supply fluid to the first pump stage 116 of a supercooled cryogenic pump 100 at a pressure greater than a head approximately 125 feet higher than the fluid inlet 124 and a fluid temperature greater than 4 Kelvin at the fluid inlet 124. In yet another example, the inducer 128 may guide fluid to the inducer guide vane 132 to supply fluid to the first pump stage 116 of a supercooled cryogenic pump 100 at a pressure greater than a head approximately 140 feet higher than the fluid inlet 124 and a fluid temperature greater than 5 Kelvin at the fluid inlet 124.

[0086] While this disclosure is described herein in relation to specific illustrated embodiments, those skilled in the art will recognize and understand that the disclosure is not limited in that way. Rather, many additions, deletions, and modifications may be made to the illustrated embodiments without departing from the scope of the claimed disclosure, including its legal equivalents. Furthermore, features from one embodiment may be combined with features from another embodiment, while still being included within the scope of the disclosure as intended by the inventors.

Claims

1. An inducer for a cryogenic pump, wherein the inducer is A hub having an outer surface extending from the front end to the rear end, wherein the outer surface has a first cylindrical front portion, a frustoconical intermediate portion, and a second cylindrical rear portion. A main blade, wherein the main blade extends radially from the outer side surface of the hub toward the outer diameter of the inducer and extends circumferentially along a first helical path across the front, middle, and rear portions, the first helical path having a helical angle that increases from the front to the rear portion, defining the main blade angle of the main blade, A splitter blade, wherein the splitter blade extends radially from the outer surface of the hub toward the outer diameter of the inducer and extends circumferentially along a second helical path across at least the intermediate and rear surfaces of the outer surface of the hub, the second helical path having a helical angle that increases from the front to the rear, defining the splitter blade angle of the splitter blade, and each of the splitter blades is located between two of the main blades. An inducer equipped with these features.

2. The inducer according to claim 1, wherein the diameter of the rear surface portion of the hub is at least about 75% of the outer diameter of the inducer.

3. The inducer according to claim 2, wherein the diameter of the rear surface portion of the hub is approximately 78% of the outer diameter of the inducer.

4. The inducer according to claim 2, wherein the diameter of the front portion of the hub is less than approximately 33% of the outer diameter of the inducer.

5. The inducer according to claim 4, wherein the diameter of the front portion of the hub is approximately 30% of the outer diameter of the inducer.

6. The inducer according to any one of claims 1 to 5, wherein each of the main blades has a curved leading edge, and the curved leading edge is defined by a radial blade length that gradually increases over a curvature angle of at least 40° from the front tip located on the front portion of the hub to the rear end located on the outer diameter of the inducer.

7. The inducer according to any one of claims 1 to 5, wherein the leading edge of each splitter blade is positioned relatively closer to the circumferentially trailing main blade than to the circumferentially preceding main blade.

8. The inducer according to any one of claims 1 to 5, wherein the front portion of the hub is greater than 5% of the axial length of the inducer, and the rear portion of the hub is greater than 5% of the axial length of the inducer.

9. The inducer according to any one of claims 1 to 5, wherein each of the main blades and each of the splitter blades has an arched outer surface that defines the outer diameter of the inducer.

10. The inducer according to claim 9, wherein one or more of the main blades have a full winding angle of approximately 180°.

11. The inducer according to any one of claims 1 to 5, wherein the angle of one or more of the main blades at the outer diameter of the inducer is smaller than the angle of the main blades at the outer side surface of the hub corresponding to the same axial position.

12. The inducer according to claim 11, wherein the angle of one or more of the main blades at the leading edge position on the outer side surface of the hub is less than approximately 25°.

13. The inducer according to claim 12, wherein the angle of one or more of the main blades at the trailing edge position on the outer side surface of the hub is greater than approximately 27°.

14. The inducer according to claim 13, wherein the angle of one or more of the main blades at the leading edge position in the outer diameter of the inducer is less than approximately 8.5°.

15. The inducer according to claim 14, wherein the angle of one or more of the main blades at the trailing edge position in the outer diameter of the inducer is greater than approximately 20°.

16. A pump for pumping a low-temperature fluid, wherein the pump is Fluid inlet and fluid outlet, Motor and, Pump stage, An inducer located between the fluid inlet and the pump stage, wherein the inducer is A hub having an outer surface extending from the front end to the rear end, wherein the outer surface has a first cylindrical front portion, a frustoconical intermediate portion, and a second cylindrical rear portion. A main blade, wherein the main blade extends radially from the outer side surface of the hub to the outer diameter of the inducer and extends circumferentially from the front portion to the rear portion along a first helical path, and the main blade has an increasing helical angle from the front portion to the rear portion, A splitter blade, wherein the splitter blade extends radially from the outer side surface of the hub to the outer diameter of the inducer, and extends circumferentially along a second helical path from the intermediate surface to the rear surface of the outer side surface of the hub, and the splitter blade has an increasing helical angle from the front surface to the rear surface, Equipped with an inducer, The motor is coupled to the pump stage and the inducer by a drive shaft, A pump equipped with the following features.

17. The pump according to claim 16, further comprising an inducer guide vane located between the inducer and the pump stage.

18. A method for inducing flow to a cryogenic pump, the method comprising the steps of rotating an inducer to draw fluid through a fluid inlet by the inducer and guide the fluid to inducer guide vanes to provide fluid to a first pump stage of the cryogenic pump at a pressure greater than a water head about 100 feet higher than the fluid inlet and supercooled to more than 3 Kelvin degrees relative to the fluid temperature at the fluid inlet.

19. The method according to claim 18, further comprising the step of supplying fluid to the first pump stage of the cryogenic pump under a pressure greater than a water head approximately 140 feet higher than the fluid inlet and supercooled to more than 5 Kelvin degrees relative to the fluid temperature at the fluid inlet.

20. The method according to claim 18 or 19, further comprising the steps of recondensing a fluid having a vapor fraction of more than 18% at the fluid inlet, and delivering the supercooled liquid fluid to the first pump stage.

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