PUMPING APPARATUS

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119 (a) and (b) to French patent application No. FR2413613, filed Dec. 6, 2024, which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to a pumping apparatus comprising fluid machines and a member for collecting leaks from one machine to another. These in particular are positive-displacement fluid machines (pumps, compressors) for a cryogenic fluid. The fluid concerned may be hydrogen.

The invention also relates to a compressor or to a pump comprising such a pumping apparatus.

BACKGROUND OF THE INVENTION

A fluid machine comprises, for example, a tubular piston, a fixed guide located inside the tubular piston, a chamber delimited by the piston and the guide, and a set of seal(s) arranged between the piston and the guide. The piston and guide are configured to reciprocate relative to each other between a fluid-inlet configuration admitting fluid into the chamber and a fluid-compression configuration compressing the fluid in the chamber.

Despite the recent progress made in recent years in the design of fluid machines, the fluidtightness of the chamber delimited by the piston and the guide remains difficult to guarantee, especially during the compression phase of compressing the fluid in the chamber. In particular, as the seals become worn, a path or passage is created between these seals and the piston, causing leakage to flow from the chamber.

This leakage flow can be vented or returned to a source that feeds the fluid machine (in the case of a compressor or pump). This leakage flow therefore constitutes a loss of material which affects the volumetric efficiency of the fluid machine and consequently the discharge flow rate. Furthermore, when the leakage flow is returned to the source that feeds the fluid machine, this flow expands and generates heat in the source. This results in boil-off gas, or BOG, as fluid in the source evaporates.

SUMMARY OF THE INVENTION

Whether it is vented or returned to the source supplying the fluid machine, the leakage flow is not sufficiently utilized. One object of the invention is to overcome this drawback.

To this end, a first aspect of the invention relates to a pumping apparatus.

The pumping apparatus comprises a first fluid machine and a second fluid machine each comprising a piston and a guide delimiting a first chamber for the compression and expansion of a fluid. The piston and the guide are movable relative to each other for the compression and expansion of the fluid in the first chamber. The first fluid machine and the second fluid machine each also comprise a sealing device disposed between the piston and the guide.

According to this first aspect of the invention, the pumping apparatus comprises a collecting member configured to collect at least part of the leaks which have migrated through the sealing device of one of the fluid machines and to direct these collected leaks into the first chamber of the other of the fluid machines.

Embodiments of the first aspect of the invention my comprise one or more of the following features:

• • the first fluid machine and the second fluid machine are configured to operate in an antagonistic mode, which is to say that an expansion configuration in the first fluid machine coincides with a compression configuration in the second fluid machine, and vice versa,
  • the first fluid machine and the second fluid machine each comprise at least one leakage path between the sealing device and the piston,
  • the collecting member has a first end in fluidic communication with the leakage path of one of the fluid machines and a second end in fluidic communication with the first compression chamber of the other of the fluid machines,
  • the collecting member further comprises at one of the fluid machines a first nonreturn valve configured to control the circulation of fluid between the collecting member and the leakage path of said machine,
  • the collecting member also comprises at the other of the fluid machines a second nonreturn valve configured to control the circulation of fluid between the collecting member and the first compression chamber of said fluid machine,
  • the apparatus comprises a venting conduit connected to the collecting member and configured to discharge a portion of the collected leakage stream to outside the fluid machines,
  • the sealing device comprises a set of O-ring seals disposed in housings provided between the piston and the guide,
  • each fluid machine comprises an intake system for admitting fluid into the first chamber,
  • each fluid machine comprises a discharge system for discharging the compressed fluid from the first expansion and compression chamber,
  • at least one of the fluid machines comprises a second expansion and compression chamber delimited by the piston and/or the guide and a cylinder,
  • the second chamber is in communication with the first chamber via a transfer system,
  • the fluid machine is of the two-stage compression type, which is to say that the fluid is first admitted to the second chamber where it is compressed for a first time, then transferred via the transfer system into the first chamber where it can be compressed for a second time,
  • the piston or the guide is configured to be in reciprocating relative motion with respect to the cylinder,
  • the collecting member is configured to transfer at least a portion of the leakages that have migrated through the sealing device of one of the fluid machines to the first compression chamber of the other of the fluid machines,
  • the collecting member is configured to transfer at least a portion of the leakages that have migrated through the sealing device of one of the fluid machines to the second chamber of the other of the fluid machines.
  • A second aspect of the invention relates to a compressor or pump notably for a cryogenic fluid such as hydrogen, the compressor or the pump comprising a pumping apparatus according to any one of the embodiments described above.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, claims, and accompanying drawings. It is to be noted, however, that the drawings illustrate only several embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it can admit to other equally effective embodiments.

Further specific features and advantages will become apparent upon reading the description below, which is provided with reference to the following figures, in which:

FIG. 1 is a schematic view illustrating a pump according to a first embodiment of the invention, the pump comprising a pumping apparatus comprising a first fluid machine, a second fluid machine, and a collecting member for collecting leaks from one machine to the other, each machine comprising a piston and a guide delimiting a first chamber.

FIG. 2 is a schematic view in cross section illustrating the pump of FIG. 1 in a second configuration.

FIG. 3 is a schematic view in cross section illustrating the pump of FIG. 1 in a third configuration.

FIG. 4 is a schematic view in cross section illustrating the pump of FIG. 1 in a fourth configuration.

FIG. 5 is a schematic view illustrating a pump according to a second embodiment of the invention, in which each fluid machine further comprises a cylinder containing the piston, the cylinder and the piston delimiting a second chamber.

FIG. 6 is a schematic view of the pump of FIG. 5 in a second configuration.

FIG. 7 is a schematic view of the pump of FIG. 5 in a third configuration.

FIG. 8 is a schematic view of the pump of FIG. 5 in a fourth configuration.

FIG. 9 is a schematic view of a variant of the pump illustrated in FIG. 5, the pumping apparatus comprising a first collecting member connecting the first chamber of the first fluid machine to the second chamber of the second fluid machine, and a second collecting member connecting the first chamber of the second fluid machine to the second chamber of the first fluid machine.

FIG. 10 is a schematic view of the pump of FIG. 9 in a second configuration.

FIG. 11 is a schematic view of the pump of FIG. 9 in a third configuration.

FIG. 12 is a schematic view of the pump of FIG. 9 in a fourth configuration.

FIG. 13 illustrates examples of the mutual arrangements of the discharge orifices and of the transfer orifices in one of the fluid machines illustrated in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 to FIG. 12 illustrate a pump or a compressor 100 intended to supply a system (not illustrated) with cryogenic fluid under pressure.

The pump 100 comprises a reservoir 1 for storing a fluid 2 and a pumping apparatus 3 comprising a plurality of fluid machines 3A, 3B disposed in the reservoir 1. The fluid machines 3A, 3B are immersed in the fluid 2 in order to pump the latter with a view to compressing it. The reservoir 1 may be thermally insulated, notably in the event that it contains a liquefied cryogenic fluid.

In the examples illustrated, the compressor or pump 100 comprises two fluid machines: a first fluid machine 3A and a second fluid machine 3B.

Each fluid machine 3A, 3B comprises a piston 4, a guide 5 arranged inside the piston 4, a first chamber 61 delimited by the piston 4 and the guide 5, and a sealing device 7 arranged between the piston 4 and the guide 5. In particular, the piston 4 and the guide 5 are configured to move translationally relative to each other between a fluid-inlet configuration admitting fluid into the first chamber 61 and a fluid-compression configuration compressing the fluid in the first chamber 61. As depicted in figures, the piston 4 is tubular and slipped over the guide 5.

The first fluid machine 3A and the second fluid machine 3B are distinct and independent, as depicted. That means to say that the first fluid machine 3A and the second fluid machine 3B each comprise a distinct respective guide-piston assembly and can each be actuated independently. For example, the reciprocating movements of the pistons are independent and controlled relative to one another.

In the example illustrated, the first fluid machine 3A and the second fluid machine 3B are configured to operate in an antagonistic mode (offset or phase-shifted), which is to say that the inlet configuration in the first fluid machine 3A coincides with the discharge configuration in the second fluid machine 3B, and vice versa.

Moreover, the piston 4 and the guide 5 are cylindrical in shape. More specifically, the piston 4 may comprise a periphery 41, a first base 42 and a second base 43 on the opposite side of the periphery 41 from the first base 42. Likewise, the guide 5 comprises a periphery 51, a first end 52 and a second end 53 on the opposite side of the periphery 51 from the first end 52. The first end 52 of the guide 5 faces the first base 42 of the piston 4.

Thus, in each fluid machine 3A, 3B, the first chamber 61 is delimited by the first end 52 of the guide 5 as well as by the periphery 41 and the first base 42 of the piston 4.

The first chamber 61 thus delimited is in fluid communication with the volume of the reservoir 1 of the pump 100 via a first intake system. Furthermore, the first chamber 61 is in fluid communication with the outside of the pump 100 (for example, a system intended to be supplied by the compressor or the pump 100) through a first discharge system.

In other words, the first intake system of each pump 100 is configured to place each first chamber 61 in fluid communication with the volume of the reservoir 1 of the pump 100. Thus, each first chamber is configured to be supplied with fluid at the same pressure, here equal to the pressure prevailing in the reservoir 1 of the pump 100.

The first intake system comprises at least a first intake orifice 44. The latter is provided with a first inlet valve 44a intended to fluidically connect the first chamber 61 and the volume of the reservoir 1 of the pump 100. In the example illustrated, the first intake orifice or orifices 44 are formed at the first base 42 of the piston 4.

The first discharge system comprises at least a first discharge orifice 54 which allows the fluid compressed in the chamber 61 to be discharged therefrom. The first discharge orifice or orifices 54 are each provided with a first discharge valve 54a. In the example illustrated, the first discharge orifice or orifices 54 are formed at the first end 52 of the guide 5.

In order to convey the compressed fluid to the outside of the pump 100, the first discharge system of each fluid machine 3A, 3B preferably comprises at least one discharge conduit 55.

In each fluid machine 3A, 3B, the discharge conduit or conduits 55 each extend inside the guide 5 from the first discharge orifice 54. Furthermore, the discharge conduit or conduits 55 open out of the machine 3A, 3B through the second end 53 of the guide 5.

In the example illustrated, each fluid machine 3A, 3B comprises a single discharge conduit 55 which extends from the first discharge orifice 54 formed at the first end 52 of the guide 5.

In a variant which has not been illustrated, each fluid machine 3A, 3B comprises two discharge conduits 55 which extend respectively from two first discharge orifices 54 formed at the first end 52 of the guide 5. These two discharge conduits 55 merge to form a single conduit outside the fluid machine 3A, 3B.

The sealing device 7 comprises a plurality of seals. In order to allow these seals 7 to be fitted in each fluid machine 3A, 3B, the periphery 51 of the guide 5 may comprise notches which form annular grooves. The seals 7 are thus disposed in these grooves and are configured to come into contact radially with an inner face of the periphery 41 of the piston 4.

Because of the relative movement between the piston 4 and the guide 5, the seals 7 mounted on the guide 5 are also in relative movement with respect to the piston 4. The seals 7 are said to be dynamic seals.

In the example illustrated, the seals 7 are divided into two longitudinal series: a first series located close to the first end 52 of the guide 5 (at the bottom when the machine 3A, 3B is arranged vertically in the configuration of use), and a second series situated close to the second end 53 of the guide 5 (at the top when the machine 3A, 3B is arranged vertically in the configuration of use).

Advantageously, the seals 7 of the first series have a thermal expansion coefficient that is different from that of the seals 7 of the second series.

During the life cycle of the pump 100, the seals 7 and the inner wall of the periphery 41 of the piston 4 are not always arranged as a tight fit. Moreover, with the wearing of the seals 7, it is found that at least one path or passage begins to form between these seals 7 and the inner face of the periphery 41 of the piston 4. A portion of the fluid admitted into and then compressed in the first chamber 61 is then able to escape from this first chamber 61 via one of these paths.

This lost part of the fluid is hereinafter referred to as “leaks” or “leakage flow”. The path formed by the seals 7 and the inner face of the periphery 41 of the piston 4, and along which the leaks pass, is hereinafter referred to as the “leakage path”.

In order to make advantageous profitable use of the leaks produced by the fluid machines 3A, 3B, the invention introduces a collecting member 8 configured to recover a leakage flow originating from any one of these fluid machines 3A, 3B and to transfer said flow to any other of these fluid machines 3A, 3B.

More specifically, the collecting member 8 is configured to recover a leakage flow from one or more leakage paths present in any one of the fluid machines 3A, 3B and to transfer this leakage flow to the first chamber 61 of any other of the fluid machines 3A, 3B. In other words, the collecting member 8 has a first end in fluidic communication with the leakage path of one of the fluid machines 3A, 3B and a second end in fluidic communication with the first compression chamber 61 of the other of the fluid machines 3A, 3B.

The collecting member 8 is therefore configured to recover a leakage flow produced at the outlet or at the first chamber 61 of any one of the fluid machines 3A, 3B and to transfer it into the first chamber 61 of any other of the fluid machines 3A, 3B. This means that the leakage flow is transferred into a first chamber 61 working at the same intake pressure as the other first chamber 61.

Thanks to the collecting member 8 and the complete or partial recycling of leaks which it allows, the invention significantly increases the efficiency of the pump 100 and reduces the operating cost of the latter. Moreover, by virtue of the collecting member 8, the discharge flow rate of the pump 100 remains relatively stable, even in the event of wearing of the seals 7, as long as it remains possible to recover and recycle the leaks. Finally, by virtue of the collecting member 8, the invention makes it possible to reduce the level of BOG or keep it at a low level, thus reducing the frequency of maintenance operations on the pump 100.

In the example illustrated, the collecting member 8 is configured to recover a first leakage flow from the leakage path or paths of the first fluid machine 3A and to transfer this first flow to the first chamber 61 of the second fluid machine 3B. Likewise, the collecting member 8 is configured to recover a second leakage flow from the leakage path or paths of the second fluid machine 3B and to transfer this second flow to the first chamber 61 of the first fluid machine 3A.

In order to do so, the connecting member 8 comprises a main conduit 81 which extends between the first fluid machine 3A and the second fluid machine 3B. In particular, the main conduit 81 extends between the first chamber of one of the fluid machines 3A, 3B and the first chamber of the other of the fluid machines 3A, 3B.

In addition, the collecting member 8 comprises at each fluid machine 3A, 3B at least one secondary conduit 82 which has a first end connected to the main conduit 81 and a second end disposed through a lateral opening 57 (gap, volume or other) formed between the piston 4 and the guide 5.

This lateral opening 57 is formed, for example, at a notch in the periphery 51 of the guide 5, preferably between the two series of seals 7. In addition, this lateral opening 57 forms a point through which the leakage path or paths of the fluid machine 3A, 3B open into the collecting member 8. Finally, this lateral opening 57 is preferably provided with a collecting valve 57a intended to fluidically connect or fluidically isolate the collecting member 8 with respect to the leakage path(s) of the fluid machine 3A, 3B. Advantageously, this collecting valve 57 may be a one-way nonreturn valve.

At each fluid machine 3A, 3B, the main conduit 81 opens out into the first chamber 61 through an injection orifice 56. The latter is preferably provided with a valve 56a, for example a nonreturn valve, intended to provide fluidic and one-way connection between the collecting member 8 and the first chamber 61 of the machine 3A, 3B concerned.

Advantageously, the injection orifice 56 of each fluid machine 3A, 3B is formed at the first end 52 of the guide 5, which end delimits the first chamber 61 of the fluid machine 3A, 3B concerned.

It should be noted that the main conduit 81 comprises, at each fluid machine 3A, 3B, a portion which extends inside said fluid machine 3A, 3B, and a portion which extends outside the fluid machines 3A, 3B. In order to limit the boil-off of a leakage flow through the portion of the main conduit 81 which extends outside the fluid machines 3A, 3B, the collecting member 8 is advantageously provided with a cooling system (not illustrated).

It should also be noted that in each fluid machine 3A, 3B, the first end 52 of the guide 5 bears both the discharge orifice or orifices 54 and the injection orifice or orifices 56. It is possible to envisage, at the first end 52 of the guide 5, different mutual arrangements of the injection orifices 56 and discharge orifices 54, depending on the respective number of them. FIG. 13 illustrates some examples of mutual arrangements of discharge orifices 54 and injection orifices 56 at the first end 52 of the guide 5.

In a first example (a), the first end 52 of the guide 5 bears a single first discharge orifice 54 and a single injection orifice 56. The two discharge orifices 54, 56 are located along a diameter of the first end 52 of the guide 5. The two orifices 54, 56 are located at equal distances from the centre of the first end 52 of the guide 5.

In a second example (b), the first end 52 of the guide 5 bears a single injection orifice 56 and two discharge orifices 54. The injection orifice 56 is arranged at the centre of the end 52 of the guide 5 between the two discharge orifices 54.

In a third example (c), the first end 52 of the guide 5 bears a single injection orifice 56 and three discharge orifices 54. The injection orifice 56 is arranged at the centre of the end 52 of the guide 5. The discharge orifices 54 are arranged at regular spacings around the injection orifice 56.

Advantageously, the pumping apparatus 3 comprises a discharge conduit 83 connected to the collecting member 8. The discharge conduit 83 is configured to discharge part of the leakage flow collected by the collecting member 8 outside of the fluid machines 3A, 3B, notably when the flow rate of the collected leaks is very high. The discharge conduit 83 may be equipped with a flowmeter, measurements from which can indicate the state of wear of the seals 7.

FIG. 1 to FIG. 4 illustrate an operating cycle of the pump 100.

In a configuration illustrated in FIG. 1, the first fluid machine 3A is at the end of admitting a flow of the fluid 2 contained in the reservoir 1 while the second fluid machine 3B is at the end of compressing the fluid, at the end of discharging the compressed fluid to the outside, and at the end of transferring leaks to the first chamber 61 of the first machine 3A.

At the first fluid machine 3A, the first inlet valve 44a and the injection valve 56a are open while the collecting valves 57a and the discharge valve 54a are closed. At the second fluid machine 3B, the first inlet valve 44a and the injection valve 56a are closed, while the collecting valves 57a and the discharge valve 54a are open.

In a configuration illustrated in [FIG. 2], the first fluid machine 3A is in the compression phase, and the member 8 then collects the leaks coming from the first fluid machine 3A in order to transfer them to the first chamber 61 of the second fluid machine 3B. The second fluid machine 3B is at the end of admitting a flow of the fluid 2 contained in the reservoir 1.

At the first fluid machine 3A, the first inlet valve 44a, the injection valve 56a and the discharge valves 54a are closed, while the collecting valves 57a are open. At the second fluid machine 3B, the collecting valves 57a and the discharge valve 54a are closed, while the injection valve 56a is open.

In a configuration illustrated in FIG. 3, the first fluid machine 3A is in the fluid compression and discharge phase. The member 8 collects a leakage flow of the leaks coming from the first machine 3A in order to transfer them to the second machine 3B. The second fluid machine 3B is in the phase of admitting a flow of the fluid 2 coming from the reservoir 1 and in the phase of mixing this flow with the leakage flow received from the collecting member 8.

At the first fluid machine 3A, the first inlet valve 44a and the injection valve 56a remain closed, while the collecting valves 57a and the discharge valve 54a are open. At the second fluid machine 3B, the injection valve 56a and the first inlet valve 44a remain open, while the collecting valves 57a and the discharge valve 54a remain closed.

Finally, in a configuration illustrated in FIG. 4, the first fluid machine 3A is in the end compression phase and at the end of discharging the compressed fluid to the outside. The member 8 collects a leakage flow of the leaks from the first machine 3A to the second fluid machine 3B. The second fluid machine 3B is in the phase of admitting a flow of the fluid 2 from the reservoir 1 and at the end of mixing this flow with the leakage flow received from the collecting member 8.

At the first fluid machine 3A, the first inlet valve 44a and the injection valve 56a remain closed, while the collecting valves 57a and the discharge valve 54a remain open. At the second fluid machine 3B, the injection valve 56a and the first inlet valve 44a remain open. The collecting valves 57a and the discharge valve 54a remain closed.

The first fluid machine 3A and the second fluid machine 3B can therefore be configured to work in phase opposition, and the leak collecting member 8 is configured to recover the leaks produced by one of the machines 3A, 3B, which is then in the compression phase, and inject them into the other fluid machine 3A, 3B, which is then in the admission phase.

A second embodiment of the invention is now described with reference to FIG. 5 to FIG. 12.

This second embodiment reproduces the features of the first embodiment described above. One difference here lies in the fact that each fluid machine 3A, 3B is of the type having two compression stages. Another difference lies in the fact that each fluid machine 3A, 3B further comprises a cylinder 9 containing the piston 4.

In particular, the cylinder 9 and the piston 4 delimit a second chamber 62. Furthermore, the piston 4 and the cylinder 9 are movable relative to each other for the compression and expansion of the fluid in the second chamber 62.

For the operation of the pump 100 according to this second embodiment, the fluid 2 is first admitted into the second chamber 62 where it is compressed for a first time and then transferred via a transfer system into the first chamber 61 where it can be compressed for a second time, before being discharged to the outside via the first discharge system described above.

The second chamber 62 communicates with the reservoir 1 of the pump 100 by means of a second intake system and by means of a second discharge system. In particular, the second intake system is configured to place the second chamber 62 of each fluid machine 3A, 3B in fluid communication with the reservoir 1 of the pump 100. That means to say that each second chamber 62 is configured to be supplied with fluid at the same pressure, here equal to the pressure prevailing in the reservoir 1 of the pump 100.

The second intake system comprises at least one port 94 and at least one second intake orifice 95 which may be equipped with a second inlet valve 95a. The second discharge system comprises at least one second discharge orifice 96 equipped with a second discharge valve 96a.

In the example illustrated, the cylinder 9 comprises a lateral wall 91, a first end wall 92 and a second end wall 93, on the opposite side of the lateral wall 91 from the first end wall 92. The port 94 is formed in the lateral wall 91. The second intake orifice 95 is formed in the first end wall 92 of the cylinder 9. Likewise, the second discharge orifice 96 is also formed in the first end wall 92 of the cylinder 9.

The transfer system transferring between the second chamber 62 and the first chamber 61 comprises at least one transfer orifice which is equipped with a transfer valve. The transfer orifice may also be fitted with a diffuser.

In particular, the transfer valve is designed to cause the fluid to pass from the second chamber 62 to the first chamber 61 with as few restrictions as possible while withstanding a high pressure during compression of the fluid in the first chamber 61. The diffuser is intended to promote mixing between a flow of the fluid 2 coming from the reservoir 1 of the pump 100 and a leakage flow recovered by the collecting member 8.

Advantageously, the transfer orifice or orifices are formed by the first intake orifice or orifices 44 formed at the first base 42 of the piston 4. Similarly, the transfer valve or valves are also formed by the first inlet valve or valves 44a provided at the first base 42 of the piston 4.

In order to seal the second chamber 62, seals are provided between the periphery 41 of the piston 4 and the lateral wall 91 of the casing. For the purpose of fitting these seals, the periphery 41 of the piston 4 may be provided with notches forming receiving grooves. The seals provided between the piston 4 and the cylinder 9 may be of the same nature as the seals 7 provided between the guide 5 and the piston 4.

Hereinafter, the second chamber 62 will also be designated by the expression “first compression stage”. The first chamber 61 will also be designated by the expression “second compression stage”.

In a first variant of this second embodiment illustrated in FIG. 5 to [FIG. 8], the collecting member 8 is configured to recover a first leakage flow coming from the first chamber 61 of the first fluid machine 3A and to transfer said first flow into the first chamber 61 of the second fluid machine 3B. Similarly, the collecting member 8 is configured to recover a second leakage flow coming from the first chamber 61 of the second fluid machine 3B and to transfer said second leakage flow into the first chamber 61 of the first fluid machine 3A.

That is to say that, in this configuration, the collecting member 8 is configured to recover a leakage flow produced by the second compression stage of any of the fluid machines 3A, 3B and transfer it to the second compression stage of any other of the fluid machines 3A, 3B. This means that the leakage flow is transferred into a first chamber 61 corresponding to the same second compression stage as the other first chamber 61.

In a first configuration illustrated in FIG. 5, the first fluid machine 3A is at the end of admission while the second fluid machine 3B is at the end of compression.

At the first fluid machine 3A, the second inlet valve 95a, the ports 94, the first discharge valve 54a, and the collecting valves 57a are closed. By contrast, the injection valve 56a, the transfer valve 44a and the second discharge valve 96a are open.

At the second fluid machine 3B, the second inlet valves 95a, the first discharge valve 54a, the collecting valves 57a and the ports 94 are open. By contrast, the injection valve 56a and the transfer valve 44a are closed.

In a second configuration illustrated in FIG. 6, the first fluid machine 3A is compressing and admitting. The member 8 collects a leakage flow coming from the first fluid machine 3A in order to transfer it to the second fluid machine 3B. The second fluid machine 3B is at the end of admitting a flow of the fluid 2 contained in the reservoir 1.

At the first fluid machine 3A, the injection valve 56a, the transfer valve 44a and the second discharge valve 96a are now closed. The ports 94 remain closed. By contrast, the second inlet valves 95a, the collecting valves 57a and the first discharge valve 54a are open.

At the second fluid machine 3B, the inlet valves 95a and the first discharge valve 54 are now closed. The transfer valve 44a remains closed and the ports 94 remain open. By contrast, the injection valve 56a is now open.

In a third configuration illustrated in FIG. 7, the first fluid machine 3A is in the compression and discharge phase. The member 8 collects a leakage flow coming from the first fluid machine 3A. The second fluid machine 3B is in a state of mixing of the leakage flow coming from the collecting member 8 and the flow of fluid previously admitted from the reservoir 1.

At the first fluid machine 3A, the injection valve 56a, the transfer valve 44a and the second discharge valve 96a remain closed. The first inlet valves 95a and the collecting valves 57a remain open. The first discharge valve 54a and the ports 94 are now open.

At the second fluid machine 3B, the second inlet valves 95a, the second discharge valves 96a, the first discharge valve 54, the collecting valves 57a and the ports 94 are closed. By contrast, the injection valve 56a and the transfer valve 44a are now open.

Finally, in a fourth configuration illustrated in FIG. 8, the first fluid machine 3A is at the end of compression. The member 8 is at the end of collecting. The second fluid machine 3B is at the end of admission and at the end of recovery of the leakage flow collected by the member 8.

At the first fluid machine 3A, the injection valve 56a, the transfer valve 44a and the second discharge valve 96a remain closed. The first discharge valve 54a, the collecting valves 57a and the ports 94 remain open. The second inlet valves 95a are now closed.

At the second fluid machine 3B, the inlet valves 95a, the first discharge valve 54, the collecting valves 57a and the ports 94 remain closed. The injection valve 56a remains open. By contrast, the transfer valve 44a is now closed.

In a second variant of this second embodiment illustrated in FIG. 9 to FIG. 12, two leak collecting members 8 are provided. A first collecting member 8A is configured to recover a first leakage flow from the first chamber 61 of the first fluid machine 3A and transfer said first flow into the second chamber 62 of the second fluid machine 3B. A second collecting member 8B is configured to recover a second flow coming from the first chamber 61 of the second fluid machine 3B and to transfer said second flow into the second chamber 62 of the first fluid machine 3A.

To do this, according to this variant of the invention, in each fluid machine 3A, 3B, a second injection orifice 97 is formed at the first end wall 92 of the cylinder 9. The second injection orifice 97 is provided with a second injection valve 97a.

The operation of the pump 100 according to this variant of the invention is described in connection with figures FIG. 9 to FIG. 12.

In a first configuration illustrated in FIG. 9, the first fluid machine 3A is at the end of admission. The second fluid machine 3B is at the end of compression. Only the second collecting member 8B recovers the leaks from the first chamber 61 of the second fluid machine 3B in order to transfer them to the second chamber 62 of the first fluid machine 3A.

At the first fluid machine 3A, the collecting valves 57a, the first discharge valve 54a, and the second inlet valves 95a are closed. Likewise, the ports 94 are closed. By contrast, the second injection valve 97a and the second discharge valve 96a are open.

At the second fluid machine 3B, the collecting valves 57a, the first discharge valve 54a, and the second inlet valves 95a are open. Likewise, the ports 94 are uncovered. By contrast, the transfer valve 44a, the second injection valve 97a and the second discharge valve 96a are closed.

In a configuration illustrated in FIG. 10, the first fluid machine 3A is in the compression phase. Only the first leak collecting member 8A is in service. The second fluid machine 3B is in the phase of recovering a leakage flow coming from the first collecting member 8A.

At the first fluid machine 3A, the collecting valves 57a and the second inlet valves 95a are now open. The ports 94 and the first discharge valve 54a remain closed. The transfer valve 44a, the second injection valve 97a and the second discharge valve 96a are now closed.

At the second fluid machine 3B, the collecting valves 57a, the first discharge valve 54a, the second inlet valves 95a, and the second discharge valve 96a are now closed. By contrast, the second injection valve 97a is now open. The ports 94 remain uncovered.

In a configuration illustrated in At the first fluid machine 3A, the collecting valves 57a and the second inlet valves 95a remain open. The first discharge valve 54a and the ports 94 are now open. The transfer valve 44a, the second injection valve 97a and the second discharge valve 96a remain closed.

At the second fluid machine 3B, the collecting valves 57a, the first discharge valve 54a, the second inlet valves 95a, and the second discharge valve 96a remain closed, while the second injection valve 97a and the transfer valve 44a remain open. The ports 94 are now closed.

In a configuration illustrated in FIG. 12, the first fluid machine 3A is at the end of compression. The first collecting member 8A remains in service. The second fluid machine 3B is at the end of admission.

At the first fluid machine 3A, the collecting valves 57a and the first discharge valve 54a and the ports 94 remain open, while the transfer valve 44a, the second injection valve 97a and the second discharge valve 96a remain closed. The second inlet valves 95a are now closed.

At the second fluid machine 3B, the collecting valves 57a, the first discharge valve 54a, the second inlet valves 95a and the ports 94 remain closed, while the second injection valve 97a remains open. Moreover, the second discharge valve 96a is now open.

In all the embodiments described, the collecting member 8 is configured to recover a leakage flow produced at the outlet or at a compression stage of a first fluid machine 3A, in this case the first chamber 61 of the machine 3A, and transfer it to the corresponding compression stage of a second fluid machine, here the first chamber 61 of the machine 3B, and vice versa.

In other words, the two fluid machines 3A, 3B have an identical or similar structure and each fluid machine 3A, 3B has the same number of compression stages. The collecting member 8 is configured to recover and transfer a leakage flow between corresponding stages of the fluid machines 3A, 3B.

The invention could also be applied to two fluid machines having a different number of compression stages, provided that the collecting member 8 is configured to recover and transfer a leakage flow between stages working at the same pressure or at similar pressures.

Advantageously, the two fluid machines 3A, 3B can be configured to work in phase opposition: the first chamber 61 of one of the fluid machines 3A, 3B is configured to be in the compression phase while the first chamber 61 of the other fluid machine 3A, 3B is in the admission phase. The collecting member 8 is then configured to transfer the leaks produced at the outlet or at the first chamber 61 which is in the compression phase, to the other first chamber 61 which is in the admission phase.

The first chamber 61 of the first fluid machine 3A and the first chamber 61 of the second machine 3B can be configured to be supplied with fluid at the same pressure.

While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.

“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.