Apparatus for compressing cryogenic fluid and filling system

Abstract

The invention relates to an apparatus (1) for compressing cryogenic fluid, comprising a sealed chamber (13) intended to contain a bath (6) of liquid cryogenic fluid, a compression chamber (3), a movable piston (5) for compressing the fluid in the compression chamber (3), and a set of one or more valves (2) configured to control the inlet and / or outlet of fluid relative to the compression chamber (3), the set of one or more valves (2) comprising at least one disc-shaped or annular valve that is movable relative to a seat (4), the valve (2) being of the composite type comprising, across its thickness, a first portion (12) and a second portion (22) that are separate and stacked, an upper face of the first portion (12) being in communication with an internal volume of the apparatus (1), a lower face of the second portion (22) being intended to engage in sealed contact with the seat (4) of the valve, the second portion (22) consisting of a material that is more flexible than the material that constitutes the first portion (12).

Description

Cryogenic fluid compression apparatus and filling system

[0001] A cryogenic fluid compression apparatus and filling system are disclosed.

[0002] The invention relates more particularly to a cryogenic fluid compression apparatus with at least one compression stage comprising a sealed enclosure intended to contain a bath of cryogenic fluid in liquid phase, a compression chamber, a movable piston for compressing the fluid in the compression chamber, and a set of valve(s) communicating with the compression chamber and configured to control the inlet and / or outlet of fluid relative to the compression chamber.

[0003] In order to increase the performance and volumetric efficiency of cryogenic pumps, for example for liquid hydrogen, it is essential that the pressurization chamber or chambers (in the case of pumps with several pressurization stages) remain very tight during the pressurization phase, especially when high discharge pressures are reached. Each compression stage has an inlet valve which, during the inlet phase, allows the chamber to be filled and, during pressurization, closes and ensures that the fluid does not return.

[0004] Seals are also provided to ensure the seal between the piston and the liner during their relative movement and in particular during pressurization.

[0005] Valves can also be used for discharge and / or to prevent overpressure in the compression chamber.

[0006] Different geometric shapes of valves are used, for example conical valves with a conical seat, spherical valves with a conical seat or solid disc or annular valves with circular seat faces.

[0007] Valve sealing is essential for pump operation, especially if the pump is cryogenic. Poor sealing significantly reduces volumetric efficiency. In fact, part of the flow rate is lost due to the Joules-Thomson effect.

[0008] In the case of hydrogen, heating may occur, causing more difficulties with intake. This is because the pressurized fluid is likely to expand through the valve in the wrong direction during the pressurization phase. This brings heat to the upstream part of the compression chamber. This can cause an additional and considerable loss of liquid by vaporization (called "boil-off gas" or "BOG"), especially when the fluid in the upstream part is close to saturation.

[0009] Additionally, poor sealing at the intake valve also creates a loss in efficiency.

[0010] Known valves have an imperfect seal at cryogenic temperatures due to roughness, roughness or manufacturing imperfections. By using materials

[0011] An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

[0012] To this end, the apparatus according to the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that the set of valve(s) comprises at least one discoidal or annular type valve movable relative to a seat, the valve being of the composite type comprising, according to its thickness, a first portion and a second distinct portion superimposed, an upper face of the first portion being in communication with an internal volume of the apparatus, a lower face of the second portion being intended to cooperate in sealed contact with the seat of the valve, the second portion being made of a more flexible material than the material constituting the first portion.

[0013] Furthermore, embodiments of the invention may comprise one or more of the following features: the apparatus comprises an intake system configured to allow the entry of fluid to be compressed into said compression chamber during an intake phase and prevent the exit of fluid in the compression phase, the intake system comprising at least one such discoidal or annular type valve of composite type, the upper face of the first portion being in communication with the compression chamber, the apparatus comprises a fluid discharge system configured to allow the evacuation of fluid from the compression chamber in the compression phase, the discharge system comprising at least one such discoidal or annular type valve of composite type, the apparatus comprises a depressurization system configured to allow the evacuation of fluid from the compression chamber in the event of overpressure,the depressurization system comprising at least one such discoidal or annular composite type valve, the seat comprises a shoulder formed at one end of a passage channel for the fluid, said shoulder being intended to receive the second portion in sealed contact when the valve is in the closed position, the first portion is made of a material having a hardness greater than 150 HB (Brinell Hardness), the second portion being made of a material having a hardness less than 150 HB (Brinell Hardness), the first portion is made of at least one of the following materials: stainless steel, inconel, aluminum alloy, copper alloys, the second portion being made of at least one of the following materials: polymer, PTFE, PCTFE, indium, pure copper or aluminum or relatively less hard copper or aluminum alloys, the first and second portions are assembled by screwing, brazing, coating, hot welding, cold welding, riveting,any type of surface coating, material deposit, the first portion has a thickness of between 0.5 mm and 2 mm, the second portion having a thickness of between 0.05 mm and 0.5 mm, the device comprises a third portion arranged on the lower face of the second portion and made of a material less flexible than the material constituting the second portion, that is to say that the second portion is sandwiched between the first and third portions, the third portion not covering the entire lower face of the second portion to allow contact of the second portion with the seat.,

[0014] The invention also relates to a system for filling a tank with a pressurized fluid, for example hydrogen, comprising an apparatus according to any one of the characteristics above or below and a circuit for supplying pressurized fluid by the compression apparatus.

[0015] According to other possible particularities:

[0016] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

[0017] Other features and advantages will appear on reading the description below, made with reference to the figures in which: Brief description of the figures

[0018] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:

[0019] is a schematic and partial sectional view of a filling system comprising a compression device,

[0020] is a schematic and partial perspective view illustrating an annular type valve,

[0021] is a perspective view, partially in section, of a detail of the compression apparatus according to a first embodiment of the invention,

[0022] is a perspective view, partially in section, of a detail of the compression apparatus according to a second embodiment of the invention,

[0023] is a perspective view, partially in section, of a detail of the compression apparatus according to a third embodiment of the invention,

[0024] is a perspective view, partially in section, of a detail of the compression apparatus according to a fourth embodiment of the invention. Detailed description

[0025] In all figures, the same references refer to the same elements.

[0026] In this detailed description, the following embodiments are examples. Although the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Single features of different embodiments may also be combined and / or interchanged to provide other embodiments.

[0027] The cryogenic fluid compression apparatus 1 shown schematically and partially at the is of the single-stage compression type. It comprises a sealed enclosure 13 intended to contain a bath 6 of cryogenic fluid in liquid phase and a compression chamber 3. The apparatus 1 comprises a movable piston 5 to ensure the compression of the fluid in the compression chamber 3. For example, the piston 5 is movable in a rectilinear and vertical alternating movement to successively ensure phases of admission and discharge of fluid into the compression chamber 3.

[0028] The compression apparatus 1 is here integrated into a system for filling a tank 9 with a pressurized fluid, for example hydrogen. The filling system comprises for this purpose a circuit 8 for supplying pressurized fluid by the compression apparatus 1.

[0029] The apparatus 1 comprises a set of valve(s) 2 communicating with the compression chamber and configured to control the inlet and / or outlet of fluid relative to the compression chamber 3. In this example, the apparatus 1 comprises at least one valve 2 forming part of an intake system configured to allow the inlet of fluid to be compressed into said compression chamber 3 during an intake phase and prevent the outlet of fluid in the compression phase.

[0030] In particular, the device 1 comprises at least one valve 2 of discoidal or annular type and movable relative to a seat (cf. where a ring 2 is movable relative to a fixed structure 20).

[0031] That is to say that the valve 2 comprises a movable part in the form of a disc or ring movable relative to a seat between a closed state preventing the entry or exit of fluid into the compression chamber 3 via at least one passage 7 and an open state allowing the entry of fluid via the passage 7. The valve 2 may possibly be forced by a return member (spring or other) towards its closed position.

[0032] The valve 2 is of the composite type, that is to say formed by an assembly or stacking of two structurally different parts. The valve 2 comprises, depending on its thickness, a first portion 12 and a second portion 22 distinct superimposed having different flexibility or hardness characteristics. An upper face of the first portion 12 is in communication with an internal volume of the device 1 (here the compression chamber 3) while a lower face of the second portion 22 is intended to cooperate in sealed contact with the seat 4 of the valve.

[0033] The second portion 22 which cooperates with the seat 4 and ensures sealing is made of a more flexible material than the material constituting the first portion 12.

[0034] This two-material valve structure 2 has a rigid upper disc or ring 12 (on the side of the compression chamber 3 in this example) which constitutes the rigid body of the valve associated with a more flexible lower disc or ring 22 (on the side of the seat 4) which ensures sealing upon closure. The association between the two portions 12, 22 can be achieved in different ways (screwing, brazing, coating, deposition, brazing, coating, hot welding (e.g. "tig", "mig"), cold welding (e.g. friction, pressure, etc.), riveting, any type of surface coating, material deposition (e.g. 3D printing).

[0035] Several configurations are possible.

[0036] In the example of the first 12 and second 22 portions are assembled via at least one fixing screw 9 passing through the two portions and a nut and / or thread system (or tapping in a portion 12 for example) and which can be supplemented by a sealing joint 10 such as a flexible washer for example to guarantee sealing at the tightening level.

[0037] The first portion 12 may be made of a material having a hardness greater than 150 HB (Brinell Hardness). The second portion 22 may be made of a material having a hardness less than 150 HB.

[0038] The first portion 12 may be made of at least one of the following materials: stainless steel, inconel, aluminum alloy, relatively hard copper alloys.

[0039] The second portion 22 may be made of at least one of the following materials: polymer, PTFE (Polytetrafluoroethylene), PCTFE (Polychlorotrifluoroethylene), pure or nearly pure indium, copper or aluminum.

[0040] The first 12 portion has for example a thickness between 0.5mm and 2mm. The second 22 portion has for example a thickness between 0.05mm and 0.5mm.

[0041] As illustrated, the seat 4 may comprise a first shoulder formed at one end of a channel 7 for the passage of the fluid. The shoulder, of circular shape, may be intended to receive the second portion 22 in sealed contact when the valve 2 is in the closed position (cf.).

[0042] In the variant of the, the valve comprises a third rigid portion 122 arranged on the lower face of the second portion 22. That is to say that the third portion 122 is made of a less flexible material than the material constituting the second portion 12. Thus, the second portion 22 is sandwiched between the first 12 and third 122 portions. As illustrated, the third portion 122 does not cover the entire lower face of the second portion 22 to allow contact of the second portion 22 with the seat 4.

[0043] The first 12 and third 122 portions may be made of the same material or different materials. The assembly method may be of the same type as that described previously (screw 9 in particular). This structure allows for better support of the second portion 22 and in particular to avoid excessive deformation of the latter.

[0044] In the example of the, in the closed position, the third 122 portion can be housed in the channel 7 or in a housing or on a second shoulder, without interfering with the seat 4 (first shoulder) on which the second portion 22 is placed.

[0045] As illustrated in , the second portion 22 may be formed into several distinct parts.

[0046] As illustrated in the, the first 12 and third 122 portions may be mechanically connected to each other (e.g., in contact).

[0047] In the example described above, the valve is an inlet valve. Of course, one or more valves of this type can be considered for a discharge system and / or a pressure management system (overpressure relief valve).

[0048] Thus, one or more valves of this type can be used for intake and / or discharge and / or to prevent overpressure in cryogenic pumps and / or piston volumetric compressors.

[0049] This type of solid or annular disc valve allows very high flow coefficients to be obtained with good sealing at very low temperatures. This type of valve has in particular a very good capacity to pass a flow with a relatively low pressure loss.

[0050] The invention can be applied to a compression device with several independent or non-independent compression stages (independent pistons or a piston ensuring sequential compression in two separate compression chambers).

Claims

Apparatus (1) for compressing cryogenic fluid with at least one compression stage comprising a sealed enclosure (13) intended to contain a bath (6) of cryogenic fluid in liquid phase, a compression chamber (3), a movable piston (5) for compressing the fluid in the compression chamber (3), and a set of valve(s) (2) communicating with the compression chamber (3) and configured to control the inlet and / or outlet of fluid relative to the compression chamber (3), the set of valve(s) (2) comprising at least one discoidal or annular type valve and movable relative to a seat (4), characterized in that the valve (2) is of the composite type comprising, according to its thickness, a first portion (12) and a second portion (22) distinct and superimposed, an upper face of the first portion (12) being in communication with an internal volume of the apparatus (1),a lower face of the second portion (22) being intended to cooperate in sealed contact with the seat (4) of the valve, the second portion (22) being made of a more flexible material than the material constituting the first portion (12), the first portion (12) being made of a material having a hardness greater than 150 HB (Brinell Hardness), the second portion (22) being made of a material having a hardness less than 150 HB (Brinell Hardness), the first (12) portion having a thickness of between 0.5 mm and 2 mm, the second (22) portion having a thickness of between 0.05 mm and 0.5 mm., Apparatus according to the preceding claim, characterized in that it comprises an intake system configured to allow the entry of fluid to be compressed into said compression chamber (3) during an intake phase and to prevent the exit of fluid in the compression phase, the intake system comprising at least one such discoidal or annular composite type valve (2), the upper face of the first portion (12) being in communication with the compression chamber (3). Apparatus according to any one of the preceding claims, characterized in that it comprises a fluid discharge system configured to allow the evacuation of fluid from the compression chamber (3) in the compression phase, the discharge system comprising at least one such discoidal or annular composite type valve (2). Apparatus according to any one of the preceding claims, characterized in that it comprises a depressurization system configured to allow the evacuation of fluid from the compression chamber (3) in the event of overpressure, the depressurization system comprising at least one such valve (2) of discoidal or annular type of composite type. Apparatus according to any one of the preceding claims, characterized in that the seat (4) comprises a shoulder formed at one end of a channel (7) for passage of the fluid, said shoulder being intended to receive the second portion (22) in sealed contact when the valve (2) is in the closed position. Apparatus according to any one of the preceding claims, characterized in that the first portion (12) is made of at least one of the following materials: stainless steel, inconel, aluminum alloy, copper alloys, the second portion (22) being made of at least one of the following materials: polymer, PTFE, PCTFE, indium, pure copper or aluminum or relatively less hard copper or aluminum alloys. Apparatus according to any one of the preceding claims, characterized in that the first (12) and second (22) portions are assembled by screwing, brazing, coating, hot welding, cold welding, riveting, any type of surface coating, material deposition. Apparatus according to any one of the preceding claims, characterized in that it comprises a third portion (122) arranged on the lower face of the second portion (22) and made of a less flexible material than the material constituting the second portion (12), that is to say that the second portion (22) is sandwiched between the first (12) and third (122) portions, the third portion not covering the entire lower face of the second portion (22) to allow contact of the second portion (22) with the seat (4). System for filling a tank (9) with a pressurized fluid, for example hydrogen, comprising an apparatus (1) according to any one of the preceding claims and a circuit (8) for supplying pressurized fluid by the compression apparatus (1).

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