Expansion turbine

Abstract

Provided is a feature capable of more effectively utilizing cold energy obtained by an expansion turbine. An expansion turbine 1 comprises: a housing 10; an impeller 40; an impeller chamber 12 which is provided inside the housing 10 and houses the impeller 40; an inflow passage 12in which causes high-pressure gas to flow into the impeller chamber 12 from the outside of the housing 10; and an outflow passage 12out which causes low-pressure gas expanded by rotation of the impeller 40 to flow out from the impeller chamber 12 to the outside of the housing 10. In at least a portion of all sections between the impeller chamber 12 of the outflow passage 12out and the outside of the housing 10, a vacuum heat insulation layer 14 is provided around a pipe member 10C partitioning the outflow passage 12out.

Description

expansion turbine

[0001] The present disclosure relates to expansion turbines.

[0002] BACKGROUND ART Conventionally, a technique is known in which high-pressure gas is expanded using an expansion turbine to lower the temperature of the gas and effectively utilize the resulting refrigeration energy (see Patent Document 1).

[0003] In Patent Document 1, an expansion turbine is used as a precooler in a hydrogen gas filling system that fills a tank of a hydrogen vehicle, such as a fuel cell vehicle, that uses hydrogen as fuel with high-pressure hydrogen gas.

[0004] JP 2017-150661 A

[0005] However, the gas adiabatically expanded by the expansion turbine may increase in temperature due to heat transfer between the gas and the housing before reaching the outlet of the housing, which may result in some of the refrigeration energy obtained by the expansion turbine being dissipated.

[0006] In view of the above problems, an object of the present invention is to provide a technology that enables more effective use of refrigeration energy obtained by an expansion turbine.

[0007] In order to achieve the above object, one embodiment of the present disclosure provides an expansion turbine comprising: a housing; an impeller; an impeller chamber provided inside the housing and accommodating the impeller; an inlet passage for allowing high-pressure gas to flow into the impeller chamber from outside the housing; and an outlet passage for allowing low-pressure gas expanded by rotation of the impeller to flow from the impeller chamber to the outside of the housing, wherein a space is provided around a first member that partitions the outlet passage in at least a portion of the entire section of the outlet passage between the impeller chamber and the outside of the housing.

[0008] According to the above-described embodiment, the refrigeration energy obtained by the expansion turbine can be used more effectively.

[0009] FIG. 1 is a longitudinal cross-sectional view showing the structure of a first example of an expansion turbine. FIG. 2 is a longitudinal cross-sectional view showing the structure of a second example of an expansion turbine. FIG. 3 is a longitudinal cross-sectional view showing the structure of a third example of an expansion turbine. FIG. 4 is a longitudinal cross-sectional view showing the structure of a fourth example of an expansion turbine. FIG. 5 is a longitudinal cross-sectional view showing the structure of a fifth example of an expansion turbine. FIG. 6 is a perspective view showing the structure of another example of a tube member. FIG. 7 is a cross-sectional view showing the structure of another example of a tube member. FIG. 8 is a diagram showing an example of a hydrogen gas filling system.

[0010] Hereinafter, an embodiment will be described with reference to the drawings.

[0011] [First Example of Expansion Turbine] A first example of an expansion turbine 1 according to this embodiment will be described with reference to FIG.

[0012] Hereinafter, the axial direction, radial direction, and circumferential direction based on the rotational axis AX of the expansion turbine 1 may be simply referred to as the "axial direction," the "radial direction," and the "circumferential direction."

[0013] Fig. 1 is a longitudinal cross-sectional view showing the structure of a first example of the expansion turbine 1. Specifically, Fig. 1 is a cross-sectional view taken along a plane passing through the rotation axis AX of the first example of the expansion turbine 1 and parallel to the rotation axis 20. The same applies to the longitudinal cross-sectional views of second to sixth examples described below.

[0014] In the figure, only some of the components of the expansion turbine 1 (the housing 10 and the bearing support member 31) are depicted as cross-sectional views. Furthermore, the orientation of the expansion turbine 1 itself when installed may be such that the rotation axis AX is vertical (perpendicular) as shown in the figure, or may be horizontal, as shown in Figure 1. These points also apply to the second example (Figure 2) to the fifth example (Figure 5) described below.

[0015] As shown in FIG. 1 , in this example, the expansion turbine 1 includes a housing 10 , a rotating shaft 20 , a bearing device 30 , an impeller 40 , and an impeller 50 .

[0016] The housing 10 accommodates components of the expansion turbine 1, including the rotating shaft 20, the bearing device 30, and the impellers 40 and 50, in its internal space. The housing 10 has a pressure-resistant structure with a relatively large wall thickness between its outer and inner surfaces to ensure pressure resistance against the high-pressure process gas flowing through it. The housing 10 includes an upper housing 10A, a lower housing 10B, a pipe member 10C, and a cover member 10D.

[0017] The upper housing 10A and the lower housing 10B are combined to form the main body of the housing 10. The main body of the housing 10 formed by combining the upper housing 10A and the lower housing 10B has, for example, a cylindrical or rectangular prism shape extending in the vertical direction. The upper housing 10A and the lower housing 10B have horizontal mating surfaces and an internal space formed by combining them so that the recesses provided on the mating surfaces face each other. The internal space accommodates the components of the expansion turbine 1, including the rotating shaft 20, the bearing device 30, the impeller 40, and the impeller 50.

[0018] The division configuration of the upper housing 10A and the lower housing 10B is merely an example, and various other division configurations are possible, as is the case with the second example (FIG. 2) to the fifth example (FIG. 5) described below.

[0019] The upper housing 10A is combined on top of the lower housing 10B. The upper housing 10A has, for example, a cylindrical shape. Alternatively, the upper housing 10A may have a prismatic shape (rectangular parallelepiped shape). The upper housing 10A has the above-mentioned recess formed in the center of its underside, which corresponds to the mating surface with the lower housing 10B. The recess in the underside of the upper housing 10A accommodates the rotating shaft 20, the upper part of the bearing device 30, and the impeller 50. Specifically, the recess in the underside of the upper housing 10A includes a first-stage recess that accommodates the rotating shaft 20 and the upper part of the bearing device 30, and a second-stage recess that accommodates the impeller 50.

[0020] The first-stage recess of the recesses on the underside of the upper housing 10A is formed in a shape recessed upward from the underside of the upper housing 10A. For example, the first-stage recess of the upper housing 10A has a cylindrical space with its central axis coincident with the rotation axis AX of the expansion turbine 1 and an outer diameter that is the same as or slightly larger than the outer diameter of the bearing device 30 (specifically, the bearing support member 31 described below). The second-stage recess of the upper housing 10A is formed in a shape recessed upward from the bottom surface of the innermost part of the first-stage recess. For example, the second-stage recess of the upper housing 10A has its central axis coincident with the rotation axis AX of the expansion turbine 1 and has a cylindrical space with an outer diameter that is larger than the outer diameter of the impeller 50 and smaller than the inner diameter of the first-stage recess. The second-stage recess corresponds to the impeller chamber 11 described below.

[0021] The lower housing 10B is combined below the upper housing 10A. The lower housing 10B has a cylindrical shape with upper and lower surfaces of the same shapes as the upper housing 10A. The lower housing 10B may also have a prismatic (rectangular) shape. The lower housing 10B has the above-mentioned recess formed in the center of its upper surface, which corresponds to the mating surface with the upper housing 10A. Specifically, the recess on the upper surface of the lower housing 10B includes a first-stage recess that accommodates the rotating shaft 20 and the lower part of the bearing device 30, and a second-stage recess that accommodates the impeller 40.

[0022] The first-stage recess among the recesses on the top surface of the lower housing 10B is formed to recess downward from the top surface of the lower housing 10B. For example, the first-stage recess has a central axis coincident with the rotational axis AX of the expansion turbine 1 and a cylindrical space with an outer diameter that is approximately the same as or slightly larger than the outer diameter of the bearing device 30 (specifically, the bearing support member 31). The second-stage recess among the recesses on the top surface of the lower housing 10B is formed to recess further downward from the bottom surface of the innermost part of the first-stage recess. For example, the second-stage recess has a central axis coincident with the rotational axis AX of the expansion turbine 1 and has a cylindrical space with an outer diameter that is larger than the outer diameter of the impeller 40 and smaller than the inner diameter of the first-stage recess. The second-stage recess corresponds to the impeller chamber 12, which will be described later.

[0023] In addition, a recess is provided on the bottom surface of the lower housing 10B.

[0024] The recess in the lower surface of the lower housing 10B is recessed upward from the lower surface of the lower housing 10B. For example, the recess in the lower surface of the lower housing 10B has a cylindrical space whose central axis is the rotation axis AX of the expansion turbine 1 and whose inner diameter is larger than the outer diameter of the pipe member 10C.

[0025] A through hole with a circular cross section centered on the rotation axis AX of the expansion turbine 1 runs between the bottom surface of the deepest part of the recess in the upper surface of the lower housing 10B, i.e., the bottom surface of the second-stage recess, and the bottom surface of the recess in the lower surface of the lower housing 10B. The inner diameter of this through hole is the same as or slightly larger than that of the pipe member 10C.

[0026] The pipe member 10C is provided in a recess in the lower surface of the lower housing 10B. The pipe member 10C is formed with a relatively thick wall so as not to be damaged by the pressure difference between the process gas flowing inside and the surrounding space (specifically, the vacuum insulation layer 14 described below). Specifically, the pipe member 10C is attached to the recess in the lower housing 10B by inserting its upper end from below into a through-hole that penetrates the bottom surfaces of the recesses in both the upper and lower surfaces of the lower housing 10B. For example, the upper end of the pipe member 10C is flush with the bottom surface of the innermost part of the recess in the upper surface of the lower housing 10B, and the lower end of the pipe member 10C is flush with the bottom surface of the lower housing 10B.

[0027] The pipe member 10C is not limited to a linear shape. The pipe member 10C may have a constant flow path cross section, as shown in FIG. 1, or may have a flow path cross section that changes in the direction of the process gas flow, such as a flow path area that increases toward the outlet side. These points also apply to the second example (FIG. 2) to the fifth example (FIG. 5) described below.

[0028] The cover member 10D is attached to the lower housing 10B so as to close the lower part of the space horizontally surrounding the pipe member 10C in the recessed portion on the lower surface of the lower housing 10B and seal the space. The space horizontally surrounding the pipe member 10C in the recessed portion on the lower surface of the lower housing 10B corresponds to the vacuum insulation layer 14 described below. For example, the cover member 10D has an annular shape, when viewed from below, centered on the rotation axis AX of the expansion turbine 1, with an outer diameter equal to or slightly smaller than the inner diameter of the recessed portion on the lower surface of the lower housing 10B and an inner diameter equal to or slightly larger than the outer diameter of the pipe member 10C.

[0029] As shown in FIG. 1, the direction of the rotation axis AX of the rotation shaft 20 is aligned with the vertical direction (up-down direction), so that the rotation shaft 20 is installed to extend in the vertical direction (up-down direction).

[0030] The expansion turbine 1 may be upside down in the vertical direction. Also, by aligning the direction of the rotation axis AX of the rotating shaft 20 with the horizontal direction, the rotating shaft 20 may be installed so as to extend horizontally as described above. These points also apply to the second example (FIG. 2) to the fifth example (FIG. 5) described later.

[0031] An impeller 40 for expanding a process gas is attached to one end (the lower end in this example) of the rotating shaft 20. The process gas is, for example, hydrogen gas (see FIG. 8). In equipment that does not use hydrogen fuel filling, the process gas may be helium gas, nitrogen gas, or air.

[0032] An impeller 50 that compresses the process gas is attached to the other end (the upper end in this example) of the rotating shaft 20. This allows the impeller 50 to consume the rotational energy of the rotating shaft 20 that is driven by the process gas through the impeller 40.

[0033] The impeller 50 may be replaced with a brake fan for braking or a dynamic braking device, as in the second example (FIG. 2) to the fifth example (FIG. 5) described below.

[0034] The bearing device 30 supports the radial load and thrust load on the rotating shaft 20 rotating at high speed.

[0035] The bearing device 30 includes a bearing support member 31 , a radial bearing 32 , a collar 33 , and a thrust bearing 34 .

[0036] The bearing support member 31 supports the radial bearing 32, the collar 33, and the thrust bearing 34. The rotating shaft 20 passes through the bearing support member 31 in the vertical direction. An impeller 40 is attached to one end (lower end) of the rotating shaft 20 that is exposed from one end (lower end) of the bearing support member 31, and an impeller 50 is attached to the other end (upper end) of the rotating shaft 20 that is exposed from the other end (upper end) of the bearing support member 31.

[0037] The radial bearing 32 supports a radial load on the rotating shaft 20. For example, as shown in Fig. 1, the radial bearing 32 is a tilting pad type radial bearing.

[0038] The bearing is not limited to the tilting pad type, and various other types may be adopted, as well as the second example (FIG. 2) to the fifth example (FIG. 5) described below.

[0039] In this example, two radial bearings 32 are provided, one at each end in the axial direction inside the bearing support member 31 .

[0040] The collar 33 is attached to the rotary shaft 20 and has a disk shape centered on the rotary shaft 20. The collar 33 is provided inside the bearing support member 31 at the center in the axial direction.

[0041] The collar 33 is configured to be able to receive a reaction force (hereinafter referred to as a “thrust reaction force”) generated by the thrust bearing 34 in response to the thrust load of the rotary shaft 20 .

[0042] The thrust bearing 34 supports a thrust load on the rotary shaft 20. Specifically, the thrust bearing 34 generates a thrust reaction force on the collar 33.

[0043] The thrust bearing 34 is disposed so as to face the collar 33 in the axial direction. For example, as shown in Fig. 3, two thrust bearings 34 are provided, and each is disposed so as to be adjacent to both one end (lower end) and the other end (upper end) of the rotating shaft 20 when viewed from the collar 33.

[0044] For example, as shown in FIG. 3 , the thrust bearing 34 is a hydrostatic gas bearing. Specifically, the thrust bearing 34 has injection holes 34A that inject a predetermined gas toward the collar 33. For example, the injection holes 34A are provided at predetermined intervals in the circumferential direction. The injection holes 34A communicate with a gas supply path that leads to the bearing support member 31 or the outside of the housing 10, and the predetermined gas is supplied to the injection holes 34A from the outside. The predetermined gas is, for example, the same gas as the process gas introduced into the expansion turbine 1 (specifically, the impellers 40 and 50). In this case, the process gas before being introduced into the expansion turbine 1 is branched and introduced into the gas supply path. Alternatively, the predetermined gas may be a gas dedicated to the thrust bearing 34 that is different from the process gas introduced into the expansion turbine 1.

[0045] The injected gas is discharged to the outside of the bearing support member 31 through a through hole 31A provided at a location radially outward from the collar 33 in the bearing support member 31 .

[0046] The thrust bearing 34 is not limited to the hydrostatic type shown in Fig. 1, but may be a hydrodynamic gas bearing that supports the thrust load of the rotating shaft 20 by gas film pressure between it and the collar 33. In this case, the injection holes 34A are omitted. The thrust bearing 34 may also be a combination of both hydrodynamic and hydrostatic types. These points also apply to the second example (Fig. 2) to the fifth example (Fig. 5) described below.

[0047] The injection holes 34A are provided on the surface of the thrust bearing 34 facing the collar 33, and are formed so that the injection direction of the predetermined gas is in the axial direction. As a result, the predetermined gas injected from the injection holes 34A can generate a thrust reaction force on the collar 33. Furthermore, even if the rotating shaft 20 tilts due to runout or vibration of the rotating shaft 20, causing the collar 33 to approach the thrust bearing 34, for example, the action of the injected predetermined gas can suppress abnormal approach due to an increase in the tilt of the rotating shaft 20. As a result, contact between the collar 33 and the thrust bearing 34 can be suppressed.

[0048] The housing 10 is provided with an impeller chamber 11, an inlet passage 11in, an outlet passage 11out, an impeller chamber 12, an inlet passage 12in, an outlet passage 12out, a discharge passage 13, and a vacuum insulation layer 14.

[0049] The impeller chamber 11 is a space that houses the impeller 50. The impeller chamber 11 corresponds to the space formed between the second-stage recess of the recesses on the lower surface of the upper housing 10A and the bearing device 30 (specifically, the bearing support member 31).

[0050] The inlet passage 11 in is a flow path that allows the process gas to flow into the impeller chamber 11 from outside the housing 10. For example, the inlet passage 11 in is provided in the upper housing 10A as a through-hole that passes vertically between the top surface of the upper housing 10A and the bottom surface of the second-stage recess among the recesses in the bottom surface of the upper housing 10A.

[0051] The outflow passage 11out is a flow path that allows the high-pressure process gas compressed by the impeller 50 to flow from the impeller chamber 11 to the outside of the housing 10. For example, the outflow passage 11out is formed in the upper housing 10A as a through-hole that penetrates horizontally between the inner surface of the impeller chamber 11 and the outer surface of the upper housing 10A.

[0052] The outflow path 11out does not have to have a straight pipe structure as shown in Fig. 1. This also applies to the second example (Fig. 2) to the fifth example (Fig. 5) described later.

[0053] The impeller chamber 12 is a space that houses the impeller 40. The impeller chamber 12 corresponds to the space formed between the second-stage recess of the recesses on the top surface of the lower housing 10B and the bearing device 30 (specifically, the bearing support member 31).

[0054] The inlet passage 12in is a flow path that allows the process gas to flow into the impeller chamber 12 from outside the housing 10. For example, the inlet passage 12in is formed in the lower housing 10B as a through-hole that penetrates horizontally between the inner surface of the impeller chamber 12 and the outer surface of the lower housing 10B.

[0055] The outflow path 12out is a path through which the low-pressure process gas expanded by the rotation of the impeller 40 flows from the impeller chamber 12 to the outside of the housing 10. The outflow path 12out corresponds to the pipe member 10C.

[0056] The outflow passage 12out does not have to have a straight pipe structure, and this also applies to the second example (FIG. 2) to the fifth example (FIG. 5) described later.

[0057] The exhaust path 13 is a path for exhausting the gas discharged from the through-hole 31A to the outside of the bearing support member 31 to the outside of the housing 10. For example, the exhaust path 13 is formed in the lower housing 10B as a through-hole that penetrates horizontally between a portion of the inner surface of the lower housing 10B that faces the through-hole 31A and the outer surface of the lower housing 10B.

[0058] The gas discharged from the discharge path 13 to the outside of the housing 10 may be released to the atmosphere or recovered through a predetermined system. In the latter case, the recovered gas may be returned to the gas path before being introduced into the expansion turbine 1. This also applies to the second example (FIG. 2) to the fifth example (FIG. 5) described below.

[0059] The vacuum insulation layer 14 is realized by sealing the space between the inner surface of the recessed portion on the underside of the lower housing 10B and the pipe member 10C with the cover member 10D and creating a vacuum. This allows the vacuum insulation layer 14 to suppress heat transfer between the process gas flowing through the outlet path 12out, which corresponds to the pipe member 10C, and the housing 10. Therefore, the vacuum insulation layer 14 can suppress a temperature increase of the process gas when the process gas, whose temperature has been reduced by the expansion process accompanying the rotation of the impeller 40, flows out of the housing 10 through the outlet path 12out.

[0060] In particular, in this example, the housing 10 has a pressure-resistant structure and therefore a relatively large heat capacity, and as a result, heat transfer from the process gas flowing through the outlet path 12out to the housing 10 is promoted, which may result in a large increase in the temperature of the process gas passing through the outlet path 12out.

[0061] In contrast to this, in this example, the expansion turbine 1 can suppress the dissipation of the cold energy generated by the expansion turbine 1 by the action of the vacuum insulation layer 14, and can make more effective use of the cold energy.

[0062] [Second Example of Expansion Turbine] Next, a second example of the expansion turbine 1 according to this embodiment will be described with reference to FIG.

[0063] Hereinafter, in this example, the same symbols are used for configurations that are the same as or correspond to those in the first example described above, and the explanation will focus on the parts that are different from the first example described above, and explanations of parts that are the same as or correspond to those in the first example described above may be omitted.

[0064] FIG. 2 is a vertical cross-sectional view showing the structure of a second example of the expansion turbine 1.

[0065] As shown in Figure 2, the expansion turbine 1 of this example differs from the first example described above in that the housing 10 includes a cover member 10E and a vacuum insulation layer 15 is provided in the lower housing 10B, but may be the same as the first example described above in other respects.

[0066] A recess having a circular ring shape in top view is formed radially outward from the recess formed in the center of the upper surface of the lower housing 10B. The radial width and depth of the recess in the outer circumferential portion of the upper surface of the lower housing 10B are set appropriately taking into consideration the pressure resistance required for the high-pressure process gas introduced into the expansion turbine 1. In this example, the innermost portion (bottom surface) of the recess in the outer circumferential portion of the upper surface of the lower housing 10B reaches a position very close to the lower surface of the lower housing 10B. This allows spaces corresponding to the recesses to be provided in the outer circumferential portion of the lower housing 10B over a relatively wide range in the axial direction.

[0067] Lid member 10E is attached to lower housing 10B so as to close the upper portion of the recess in the outer periphery of lower housing 10B and seal the space. The space sealed by lid member 10E corresponds to vacuum insulation layer 15. Lid member 10E has a circular ring shape in top view, similar to the recess.

[0068] The vacuum insulation layer 15 is realized by sealing a recess on the outer periphery of the top surface of the lower housing 10B with the cover member 10E and creating a vacuum. This allows the vacuum insulation layer 15 to suppress heat transfer between the housing 10 and the outside of the housing 10, thereby suppressing heat transfer from the process gas passing through the outlet channel 12out to the housing 10. Therefore, the vacuum insulation layer 15 can suppress a temperature increase of the process gas, whose temperature has been reduced by the expansion process accompanying the rotation of the impeller 40, when the process gas flows out of the housing 10 through the outlet channel 12out. Therefore, by including the vacuum insulation layer 15 in addition to the vacuum insulation layer 14, the expansion turbine 1 can further suppress a temperature increase of the process gas, whose temperature has been reduced by the expansion process, when the process gas flows out of the housing 10 through the outlet channel 12out.

[0069] [Third Example of Expansion Turbine] Next, a third example of the expansion turbine 1 according to this embodiment will be described with reference to FIG.

[0070] Hereinafter, in this example, the same symbols are used for configurations that are the same as or correspond to those in the first and second examples described above, and the explanation will focus on the parts that are different from the first and second examples described above, and explanations of parts that are the same as or correspond to those in the first and second examples described above may be omitted.

[0071] FIG. 3 is a vertical cross-sectional view showing the structure of a third example of the expansion turbine 1.

[0072] As shown in Figure 3, the expansion turbine 1 of this example differs from the first and second examples described above in that a refrigerant flow path 16 is provided in the lower housing 10B, but may be the same as the first example described above in other respects.

[0073] The refrigerant flow path 16 is formed inside the lower housing 10B, and a refrigerant introduced from the outside flows through it. Specifically, the refrigerant flow path 16 is formed inside the lower housing 10B so as to connect an inlet and an outlet provided on the outer surface of the housing. The refrigerant is supplied, for example, from a cold heat source 430 (see FIG. 8 ), which will be described later, and circulates between the cold heat source 430 and the refrigerant. The refrigerant is, for example, cooling water supplied from an external cooling water facility or chiller water facility serving as the cold heat source 430. This allows the expansion turbine 1 to lower the temperature of the lower housing 10B, thereby reducing the temperature difference between the process gas flowing through the outlet path 12out and the lower housing 10B, and as a result, further suppressing the temperature rise of the process gas.

[0074] In particular, when used at room temperature, the temperature difference between the lower casing 10B and the outlet path 12out becomes relatively large when the expansion turbine 1 is started, and the cold energy of the process gas may be used to pre-cool the lower casing 10B.

[0075] In contrast to this, in this example, the refrigerant can be caused to flow through the refrigerant flow path 16 before the expansion turbine 1 is started, and as a result, it is possible to reduce the temperature difference between the process gas flowing through the outlet path 12out and the lower casing 10B when the expansion turbine 1 is started. Therefore, the expansion turbine 1 can suppress dissipation of the refrigeration energy of the process gas due to pre-cooling of the lower casing 10B and the lower casing 10B.

[0076] The path and cross-sectional area of ​​the refrigerant flow path 16 are appropriately set in consideration of, for example, the pressure resistance required for the high-pressure process gas introduced into the expansion turbine 1 .

[0077] [Fourth Example of Expansion Turbine] Next, a fourth example of the expansion turbine 1 according to this embodiment will be described with reference to FIG.

[0078] Hereinafter, in this example, the same symbols are used for configurations that are the same as or correspond to those in the first to third examples described above, and the explanation will focus on the parts that are different from the first to third examples described above, and explanations of parts that are the same as or correspond to those in the first to third examples described above may be omitted.

[0079] FIG. 4 is a vertical cross-sectional view showing the structure of a fourth example of the expansion turbine 1.

[0080] As shown in Figure 4, the expansion turbine 1 of this example differs from the first example described above in that the housing 10 includes a cover member 10E, a vacuum insulation layer 15 is provided in the lower housing 10B, and a refrigerant flow path 16 is provided in the lower housing 10B, but may be the same as the first example described above in other respects.

[0081] In this way, in this example, the lower housing 10B is provided with both the vacuum insulation layer 15 and the refrigerant flow path 16. As a result, the expansion turbine 1 has both the vacuum insulation layer 15 and the refrigerant flow path 16 in addition to the vacuum insulation layer 14, and therefore can further suppress the temperature rise of the process gas as it flows out of the housing 10 through the outflow path 12out.

[0082] [Fifth Example of Expansion Turbine] Next, a fifth example of the expansion turbine 1 according to this embodiment will be described with reference to FIGS.

[0083] Hereinafter, in this example, the same symbols are used for configurations that are the same as or correspond to those in the first to fourth examples described above, and the explanation will focus on the parts that are different from the first to fourth examples described above, and explanations of parts that are the same as or correspond to those in the first to fourth examples described above may be omitted.

[0084] Fig. 5 is a longitudinal cross-sectional view showing the structure of a fifth example of the expansion turbine 1. Fig. 6 is a perspective view showing the structure of another example of the tube member 10C. Fig. 7 is a transverse cross-sectional view showing the structure of another example of the tube member 10C. Specifically, Fig. 7 is a cross-sectional view taken along a plane perpendicular to the rotation axis AX of a portion of the expansion turbine 1 including the tube member 10C.

[0085] As shown in Figures 5 to 7, the expansion turbine 1 of this example differs from the first to fifth examples described above in that the structure of the pipe member 10C and the provision of a space 17 instead of the vacuum insulation layer 14 are different, but in other respects it may be the same as the first example described above.

[0086] As in the first to fifth examples described above, the pipe member 10C is inserted into a recess in the underside of the lower housing 10B. A radial space 17 is formed between the outer surface of the pipe member 10C and the inner surface of the recess in the underside of the lower housing 10B. Unlike the vacuum insulation layer 14 in the first to fourth examples described above, the lower part of the space 17 is blocked by a joint 12jt for connecting the outflow path 12out to an external flow path.

[0087] In this example, the tube member 10C has a relatively thin wall thickness, unlike the first to fifth examples described above. Specifically, in this example, the wall thickness of the tube member 10C is set to a level below the standard for pressure resistance to the pressure of the process gas introduced into the expansion turbine 1, which is applied to the housing 10. This makes it possible to reduce the heat capacity of the tube member 10C. This suppresses heat transfer between the process gas passing through the outlet passage 12out and the tube member 10C, and as a result, it is possible to suppress a temperature rise in the process gas.

[0088] The pipe member 10C is provided with a through-hole 10CH that penetrates between the inside of the pipe member 10C and the space 17 outside. The number of through-holes 10CH may be one or more. This allows for equalization of pressure between the inside of the pipe member 10C (i.e., the outflow path 12out) and the space 17 outside the pipe member 10C. This prevents the thin-walled pipe member 10C from being damaged by the pressure difference between the outflow path 12out and the space 17.

[0089] Unlike the first to fifth examples described above, a spacer 10F is provided on the outer peripheral surface of the pipe member 10C. The spacer 10F is provided so as to protrude radially from the outer peripheral surface of the pipe member 10C, and when the pipe member 10C is inserted into a recess in the underside of the lower housing 10B, its tip abuts against the inner surface of the recess. This allows the spacer 10F to position and support the pipe member 10C in the recess while maintaining a space 17 between the outer surface of the pipe member 10C and the inner surface of the recess.

[0090] In this example, unlike the first to fifth examples described above, the inner diameter of the recess in the lower surface of the lower housing 10B is relatively small compared to the outer diameter of the pipe member 10C, and the radial gap between the outer surface of the pipe member 10C and the inner surface of the recess is relatively small. Therefore, the pipe member 10C can be fixed in the recess by the spacer 10F, which protrudes relatively little in the radial direction.

[0091] In this example, three spacers 10F are provided at equal intervals in the circumferential direction at the same vertical (axial) position, and the angular positions at which the spacers 10F are arranged are set to be different between the upper and lower parts of the pipe member 10C.

[0092] The intervals between adjacent spacers 10F in the circumferential direction at the same vertical position may be unequal. Furthermore, the number of spacers 10F provided in the circumferential direction at the same vertical position may be four or more. Furthermore, the angular positions at which the spacers 10F are arranged may be switched between three or more different positions in the vertical direction instead of two positions, upper and lower.

[0093] The spacer 10F is formed so that its width narrows as it moves radially outward from the outer surface of the tubular member 10C. For example, as shown in FIGS. 6 and 7, the spacer 10F has a pointed shape that is pointed radially outward from the outer surface of the tubular member 10C. This reduces the contact area between the spacer 10F and the inner surface of the recess in the underside of the lower housing 10B, thereby increasing the thermal resistance between the tubular member 10C and the lower housing 10B. This further suppresses heat transfer between the tubular member 10C and the lower housing 10B, thereby further suppressing the temperature rise of the process gas.

[0094] [Another Example of Expansion Turbine] Next, another example of the expansion turbine 1 according to this embodiment will be described.

[0095] The contents of the first to fifth examples described above may be combined as appropriate.

[0096] For example, the expansion turbine 1 according to the fifth example may be combined with at least one of the vacuum insulation layer 15 according to the second example and the refrigerant flow path 16 according to the third example.

[0097] [Application Example of Expansion Turbine] Next, an application example of the expansion turbine 1 according to this embodiment will be described with reference to FIG. 8 .

[0098] Fig. 8 is a diagram showing an application example of the expansion turbine 1. Specifically, Fig. 8 is a diagram showing an example of a hydrogen gas filling system SYS.

[0099] The hydrogen gas filling system SYS is installed, for example, at a hydrogen station for filling a vehicle VCL with hydrogen gas.

[0100] As shown in FIG. 8, the system includes a hydrogen gas compression facility 100, an expansion valve 200, a hydrogen gas line 300, and a pre-cooling system 400.

[0101] The hydrogen gas compression equipment 100 compresses hydrogen gas supplied from a tank, boosts the pressure to a predetermined level, and outputs the compressed hydrogen gas.

[0102] The expansion valve 200 adiabatically expands (isenthalpic expands) the hydrogen gas output from the hydrogen gas compression equipment 100. At this time, because the temperature of the hydrogen gas before expansion is higher than the inversion temperature (-58°C), the temperature of the hydrogen gas after expansion rises due to the Joule-Thomson effect.

[0103] The hydrogen gas line 300 supplies the expanded hydrogen gas output from the expansion valve 200 to the pre-cooling system 400 .

[0104] The pre-cooling system 400 cools the hydrogen gas supplied from the hydrogen gas line 300 and supplies it to the dispenser 500 .

[0105] The pre-cooling system 400 includes a compressor 410 , a chiller 420 , a cold source 430 , and an expansion section 440 .

[0106] The compressor 410 compresses the hydrogen gas supplied from the hydrogen gas line 300 .

[0107] The cooler 420 exchanges heat between the refrigerant supplied from the cold heat source 430 and the hydrogen gas compressed by the compressor 410, thereby cooling the hydrogen gas.

[0108] The cold heat source 430 supplies a refrigerant having a temperature lower than that of the hydrogen gas output from the compressor 410 to the cooler 420 and circulates it.

[0109] A cooler similar to the cooler 420 may be provided upstream of the compressor 410, and the hydrogen gas in the hydrogen gas line 300 may be introduced into the compressor 410 after being cooled by the cooler.

[0110] The expansion section 440 expands the hydrogen gas cooled by the cooler 420. This allows the hydrogen gas to expand and lower its temperature. Furthermore, by expanding the hydrogen gas compressed by the compressor 410, the expansion ratio becomes relatively large, and as a result, the temperature of the hydrogen gas can be lowered more significantly. Therefore, the temperature of the hydrogen gas can be lowered to an appropriate level without requiring a pre-cooling system that requires a refrigerator equipment including, for example, a compressor, a condenser, an expansion valve, an evaporator, an accumulator, and the like.

[0111] In this example, the compressor 410 and the expansion section 440 are realized by the expansion turbine 1. Specifically, the expansion turbine 1 realizes the function of the expansion section 440 by expanding hydrogen gas with the impeller 40 at one end of the rotary shaft 20, and realizes the function of the compressor 410 by compressing hydrogen gas with the impeller at the other end of the rotary shaft 20 as the impeller 50.

[0112] The dispenser 500 fills the hydrogen tank TNK of the vehicle VCL with high-pressure hydrogen gas supplied from the pre-cooling system 400. The vehicle VCL is, for example, a fuel cell vehicle equipped with a fuel cell capable of generating electricity using hydrogen gas as fuel.

[0113] In this way, the expansion turbine 1 can be applied to the pre-cooling system 400 of the hydrogen gas filling system SYS.

[0114] [Operation] Next, the operation of the expansion turbine according to this embodiment will be described.

[0115] In this embodiment, the expansion turbine includes a housing, an impeller, an impeller chamber, an inlet passage, and an outlet passage. The expansion turbine is, for example, the expansion turbine 1 described above. The housing is, for example, the housing 10 described above. The impeller is, for example, the impeller 40 described above. The impeller chamber is, for example, the impeller chamber 12 described above. The inlet passage is, for example, the inlet passage 12in described above. The outlet passage is, for example, the outlet passage 12out described above. Specifically, the impeller chamber is provided inside the housing and houses the impeller. The inlet passage allows high-pressure gas to flow into the impeller chamber from outside the housing. The outlet passage allows low-pressure gas expanded by rotation of the impeller to flow out of the housing from the impeller chamber. In at least a portion of the entire section of the outlet passage between the impeller chamber and the outside of the housing, a space is provided around the first member that defines the outlet passage. The first member is, for example, the above-described tubular member 10C.

[0116] As a result, the expansion turbine can suppress heat transfer between the gas flowing through the outflow passage and the housing by utilizing the space around the first member that defines the outflow passage. Therefore, the expansion turbine can suppress a temperature increase in the outflow passage of the gas whose temperature has been reduced by the expansion process in the impeller chamber. This suppresses dissipation of the refrigeration energy obtained by the expansion turbine, enabling more effective use of the refrigeration energy.

[0117] In this embodiment, the space may be a first vacuum insulation layer that is evacuated. The first vacuum insulation layer is, for example, the vacuum insulation layer 14 described above.

[0118] This allows the expansion turbine to suppress a temperature increase in the outflow passage of the gas whose temperature has been reduced by the expansion process in the impeller chamber.

[0119] In the present embodiment, the first member may have a relatively thin wall thickness relative to a predetermined standard, such as a standard applied to the housing 10 for withstanding the pressure of the process gas introduced into the expansion turbine 1.

[0120] This allows the expansion turbine to relatively reduce the heat capacity of the first member, thereby suppressing heat transfer between the first member and the gas inside the member (outlet passage). Therefore, the expansion turbine can suppress a temperature increase in the outlet passage of the gas whose temperature has been reduced by the expansion process in the impeller chamber.

[0121] In this embodiment, the first member may be provided with a through-hole that passes through between the outflow path inside the first member and the space outside the first member. The through-hole is, for example, the above-mentioned through-hole 10CH.

[0122] This makes it possible to equalize the pressure between the outflow passage inside the first member and the space outside the first member, thereby preventing the expansion turbine from suffering damage to the first member, which has a relatively thin wall thickness compared to a predetermined standard, due to the pressure difference between the space outside the first member and the outflow passage inside the first member.

[0123] In this embodiment, a second member may be provided that protrudes from the outer surface of the first member toward the outer edge of the space and abuts against the inner surface of the housing that corresponds to the outer edge of the space. The second member may be, for example, the spacer 10F described above. The second member may be formed so that its width decreases from the outer surface of the first member toward the outer surface of the space.

[0124] This allows the contact area between the second member and the inner surface of the housing to be relatively small. Therefore, the expansion turbine can support the first member using the second member while increasing the thermal resistance between the first member and the housing, thereby suppressing heat transfer between the gas in the outflow passage and the housing. Therefore, the expansion turbine can suppress a temperature increase in the outflow passage of the gas whose temperature has been reduced by the expansion process in the impeller chamber.

[0125] In this embodiment, the housing may be provided with a second vacuum insulation layer located radially outward from the space. The second vacuum insulation layer is, for example, the vacuum insulation layer 15 described above.

[0126] This makes it possible to suppress heat transfer between the housing and the outside. Therefore, the expansion turbine further suppresses heat transfer between the gas in the outflow passage and the housing, and as a result, it is possible to further suppress a temperature increase in the outflow passage of the gas whose temperature has been reduced by the expansion process in the impeller chamber.

[0127] In this embodiment, a flow path for circulating the coolant may be formed in the housing. The flow path is, for example, the coolant flow path 16 described above.

[0128] This reduces the temperature of the housing and suppresses the temperature difference between the housing and the gas in the outflow passage. Therefore, the expansion turbine further suppresses heat transfer between the gas in the outflow passage and the housing, and as a result, further suppresses the temperature rise in the outflow passage of the gas whose temperature has been reduced by the expansion process in the impeller chamber.

[0129] Although the embodiments have been described in detail above, the present disclosure is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist described in the claims.

[0130] REFERENCE SIGNS LIST 1 Expansion turbine 10 Housing 10A Upper housing 10B Lower housing 10C Pipe member 10CH Through hole 10D Lid member 10E Lid member 10F Spacer 12 Impeller chamber 12in Inlet channel 12out Outlet channel 14 Vacuum insulation layer 15 Vacuum insulation layer 16 Refrigerant flow path 17 Space 20 Rotating shaft 30 Bearing device 40 Impeller 100 Hydrogen gas compression equipment 200 Expansion valve 300 Hydrogen gas line 400 Pre-cooling system 410 Compressor 420 Cooler 430 Cold source 440 Expansion section 500 Dispenser SYS Hydrogen gas filling system TNK Hydrogen tank VCL Vehicle

Claims

1. An expansion turbine comprising: a housing; an impeller; an impeller chamber provided inside the housing and accommodating the impeller; an inlet passage for allowing high-pressure gas to flow into the impeller chamber from outside the housing; and an outlet passage for allowing low-pressure gas expanded by the rotation of the impeller to flow from the impeller chamber to the outside of the housing, wherein a space is provided around a first member that defines the outlet passage in at least a portion of the entire section of the outlet passage between the impeller chamber and the outside of the housing.

2. The expansion turbine according to claim 1, wherein the space is a first vacuum insulation layer that is evacuated.

3. The expansion turbine according to claim 1, wherein the first member has a relatively thin wall thickness with respect to a predetermined standard.

4. The expansion turbine according to claim 3, wherein the first member is provided with a through hole passing between the outlet passage therein and the space thereoutside.

5. An expansion turbine as described in claim 3 or 4, wherein a second member is provided which protrudes from the outer surface of the first member towards the outer edge of the space and abuts against the inner surface of the casing which corresponds to the outer edge of the space, and the second member is formed so that its width decreases from the outer surface of the first member towards the outer surface of the space.

6. An expansion turbine according to any one of claims 1 to 4, wherein the housing is provided with a second vacuum insulation layer located radially outward from the space.

7. The expansion turbine according to any one of claims 1 to 4, wherein a flow path for circulating a refrigerant is formed in the casing.

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