EP4078015A1

EP4078015A1 - Device for compressing gas

Info

Publication number: EP4078015A1
Application number: EP20830235.6A
Authority: EP
Inventors: Alban SESMAT; Mathieu ASSEMAT; Marc VANBALEGHEM; Jérôme CHAMPREDONDE
Original assignee: GRTgaz SA
Current assignee: GRTgaz SA
Priority date: 2019-12-20
Filing date: 2020-12-18
Publication date: 2022-10-26
Anticipated expiration: 2040-12-18
Also published as: EP4078015B1; WO2021123393A1; FR3105343B1; FR3105343A1

Abstract

The device (40) for compressing a gaseous fluid by recovering the energy from expansion of a gas between an upstream gas network (12) at pressure Pa and a downstream gas network (13) at pressure Pb, which is less than Pa, comprises: - a pneumatic booster (30) comprising a free piston (11) between an expansion chamber (17) and a compression chamber (23), - a first gas line (31) between the upstream network and an inlet of the expansion chamber, - a second gas line (32) between an outlet of the expansion chamber and the downstream network, - a third fluid line (33) of gaseous fluid to be compressed opening at an inlet of the compression chamber and - a fourth line (34) of compressed gaseous fluid connected to an outlet of the compression chamber.

Description

GAS COMPRESSION DEVICE

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a gas compression device.

It applies, in particular, to the field of natural gas stations for vehicles ("NGV"), to compressed natural gas ("CNG") networks and to compressed air tanks and networks.

STATE OF THE ART

The expansion of a gas leads to the appearance of a fatal energy, the energy of relaxation, today little or badly valued and therefore mostly or totally lost.

STATEMENT OF THE INVENTION

The present invention aims to remedy all or part of these drawbacks.

To this end, the present invention relates to a device for compressing a gaseous fluid by recovering the expansion energy of a gas between an upstream gas network under a pressure Pa and a downstream gas network under a pressure Pb less than Pa, which includes:

- a pneumatic booster comprising a free piston between an expansion chamber and a compression chamber,

- a first gas pipe between the upstream network and an inlet of the expansion chamber,

- a second gas pipe between an outlet of the expansion chamber and the downstream network,

- a third gaseous fluid line to be compressed opening onto an inlet of the compression chamber and

- A fourth compressed gaseous fluid line connected to an outlet of the compression chamber.

Thanks to these arrangements, the device which is the subject of the invention uses, in order to use the expansion energy of a fluid to compress a second, a free piston booster. The device which is the subject of the invention makes it possible, by recovering the expansion energy of a gas coming from a gas network at pressure Pa and going into a gas network at pressure Pb, where Pa> Pb, therefore without energy expenditure, compress a gaseous fluid. This gaseous fluid is, for example, gas coming from the upstream network, from a gas reservoir or from the atmosphere. Once compressed, this gaseous fluid supplies a reservoir, for example a natural gas station for vehicles ("CNG") or a compressed gas network ("CNG" or compressed air).

In embodiments:

- the free piston comprises an expansion head and a compression head connected by a shaft, a through opening opening out, on the one hand, into the expansion head on the side opposite the compression head and, on the other hand, into a side wall of the tree,

- the first gas line opens into the expansion chamber opposite the shaft and

- the outlet of the expansion chamber to which the second pipe is connected is located on a side face of the expansion chamber and is not obstructed by the expansion head until the through opening does not open into the pressure chamber. relaxation.

Thanks to these arrangements, the free piston booster operates without an external moving part as long as there is a pressure difference between the first pipe and the second pipe.

In some embodiments, the device of the invention further comprises a valve on the first pipe controlled by a pressure switch positioned downstream of the fourth pipe.

Thanks to these arrangements, an increase in pressure, downstream of the fourth pipe, causes the supply of the device to be stopped with gas to be expanded.

In some embodiments, the device of the invention further comprises an all-or-nothing pressure regulator on the first pipe, the impulse line of which is placed downstream of the fourth pipe.

In some embodiments, the third pipe is connected, at its inlet, to the upstream network, the gas to be compressed being the gas from the upstream network.

For example, since this gas is natural gas, once compressed, it supplies a reservoir of a natural gas station for vehicles ("NGV") or a compressed natural gas network ("CNG"). In some embodiments, the third pipe is connected, at its inlet, to a reservoir of gas to be compressed.

In some embodiments, the third pipe is connected, at its inlet, to the atmosphere.

In some embodiments, the fourth pipe connects the compression chamber to a compressed gas reservoir or to a compressed gas circuit.

The device can thus supply a compressed air tank or a compressed air circuit.

In some embodiments, the device of the invention further comprises a heat exchanger configured to heat the gas passing through the first pipe and to cool the compressed gaseous fluid passing through the fourth pipe.

Problems associated with the cooling of the gas correlative to its expansion are thus avoided.

In some embodiments, the device of the invention further comprises a pressure regulator on the fourth pipe.

This pressure regulator prevents pressure surges at the outlet of the fourth pipe.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages, aims and particular characteristics of the invention will emerge from the non-limiting description which follows of at least one particular embodiment of the compression device which is the subject of the present invention, with reference to the accompanying drawings, in which:

- Figure 1 shows, schematically, a first particular embodiment of the device of the invention,

- Figure 2 shows, schematically, a second particular embodiment of the device of the invention,

- Figure 3 shows, schematically, a third particular embodiment of the device of the invention,

- Figure 4 shows, schematically, a fourth particular embodiment of the device of the invention,

- Figure 5 shows, schematically, a first particular embodiment of a free piston implemented in different embodiments of the device of the invention, - Figure 6 shows, schematically, a first phase of operation of a free piston with through opening,

- Figure 7 shows, schematically, a second operating phase of a free piston with through opening,

- Figure 8 shows, schematically, a third operating phase of a free piston with through opening and

- Figure 9 shows, schematically, a fourth operating phase of a free piston with through opening.

DESCRIPTION OF EMBODIMENTS

This description is given without limitation, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment in an advantageous manner.

We note, from now on, that the figures are not to scale.

The device of the invention preferably implements, in order to use the expansion energy of one fluid to compress a second, a free-piston pneumatic booster. This is the version with a free piston which is shown in Figures 1 to 9. It is recalled that, in a free piston booster, the movement of the piston responds only to the pressure of the gas, without a connecting rod. operate where it holds. Those skilled in the art can easily replace this free piston with a pneumatic membrane booster, for example.

In the first embodiment, FIG. 1, the device 10 which is the subject of the invention makes it possible, by recovering the expansion energy of a gas, therefore without energy expenditure, to compress natural gas in order to supply a gas station. natural gas for vehicles ("CNG") or a compressed natural gas network ("CNG"), near a gas network 12 at pressure Pa and a gas network 13 at pressure Pb, where Pa> Pb.

The gas from the upstream network 12 is taken by a first pipe 31 to an inlet 18 of an expansion chamber of a booster 30 with free piston 11. Once the gas has been expanded, it joins the downstream gas network 13 via a second pipe 32. By means of a valve 15 for entering gas from the upstream network 12 via a third pipe 33, in a compression chamber 23 of the booster 30 and a gas outlet valve 16 in a fourth pipe 34, the gas is compressed to a pressure Pc greater than Pa. The compressed gas is injected into the tank 14 of a CNG station or a CNG network. Two embodiments of the free piston booster 30 are described with reference to FIGS. 5, on the one hand, and 6 to 9, on the other hand.

In embodiments, such as that illustrated in Figure 2, elements are added to automate the operation of the device 40 of the invention.

It is noted that the expansion of the gas causes a drop in its temperature, which can prove to be problematic. A heat exchanger 41 positioned on both the first pipe 31 and on the fourth pipe 34 is configured to heat the gas passing through the first pipe 31 and to cool the compressed gaseous fluid passing through the fourth pipe 34.

A pressure regulator 47 on the fourth line, upstream of the reservoir 44 is used so that the pressure and the temperature at the exchanger 41 are constant.

A valve 45 controlled by a pressure switch 46 and positioned on the first pipe 31 stops the operation of the device 40 when the tank 44 of the CNG station is sufficiently filled, that is to say that its internal pressure is equal to a limit value superior. Once the pressure of the tank 44 of the CNG station reaches a lower limit value, for example following consumption by a customer of the station, the pressure switch 46 commands the opening of the valve 45, which restarts the operation of the device 40.

Note that the assembly consisting of the valve 45 and the pressure switch 46 can be replaced by a mechanical device, the valve 45 then being replaced by an all-or-nothing pressure regulator positioned on the first pipe 31, including the impulse line is placed on the reservoir 44.

The output flow rate on the second pipe 32 of the device 40 is constant during its operation due to the fact that the pneumatic booster has a free piston. A downstream pressure regulator 48 is used to regulate the pressure of the downstream network 13 during variations in customer consumption on the downstream network 13. The valve 45 controlled by a pressure switch 49 positioned on the downstream network 13, therefore downstream of the fourth pipe 34, stops the operation of the device 40 when the customer consumption rate on the downstream network 13 is lower than the output rate of the device 40.

Note that the assembly consisting of the valve 45 and the pressure switch 49 can be replaced by a mechanical device, the valve 45 then being replaced by a all-or-nothing pressure regulator whose impulse line is placed on the downstream network 13.

It should be noted that this replacement can be carried out cumulatively with the replacement of the pressure switch 46 mentioned above. For example, two direct-acting regulators placed in series are used, each of these regulators having a specific set point. According to another example, a single pressure regulator is used with action piloted by two pilots placed in series, each of these pilots having a different set point.

In the embodiments illustrated in FIGS. 3 and 4, the device 50 and 60, respectively, makes it possible, without expenditure of energy, to compress any fluid, for example air to supply a compressed air network, which can be compressed. be contained in a reservoir, near a gas network 12 at pressure Pa and a gas network 13 at pressure Pb, where Pa> Pb. Again, the expansion energy of a gas passing from one of these networks to the other, to compress another gaseous fluid.

In the device 50 illustrated in FIG. 3, the elements illustrated in FIG. 1 are found, with the exception of the gas inlet valve 15 in the compression chamber 23, which is connected, by the third pipe 33, to a gas tank 51 to be compressed or to an ambient air inlet (not shown). The reservoir 14 can, for its part, be replaced by a gas or compressed air network.

We find, in the device 60 in Figure 4, the elements illustrated in Figure 2, with the exception of the gas inlet 15 in the compression chamber 23, which is connected, by the third pipe 33, to a reservoir 61 gas to be compressed or to an ambient air inlet (not shown). The reservoir 44 can, for its part, be replaced by a gas or compressed air network.

FIG. 5 represents a booster, that is to say a pair of pressure reducing valve 70, on the left, and compressor 72, on the right, with free piston. The regulator 70 comprises a chamber 75 provided with a high pressure gas inlet coming from the first pipe 31 and a low pressure gas outlet in the second pipe 32. In the chamber 75, an expansion piston 74 is brought into operation. movement by the pressure of the gas and transmits this pressure, via a shaft 76 to a compression piston 77 which compresses the fluid in a chamber 78. The set of pistons 74 and 77 and of the shaft 76 constitutes a free piston. Valves 15 and 16 provide the seal and the direction of movement of the fluid from the third line 33 for entering gaseous fluid at low pressure to the fourth line 34 for the outlet of high pressure fluid. The system for controlling the entry of gas into the chamber 75 and the outlet of gas from the chamber 75 is not described here, being well known to those skilled in the art.

Thus, a free piston is moved in a first chamber 75 by the gas and compresses the fluid in a second chamber 78. The compressor is driven by the turbine with very limited mechanical losses, which increases the efficiency of the compressor. relaxation station. It should be noted that the pressure of the fluid at the outlet of the compressor can be higher than the pressure of the gas at the inlet of the expansion station, depending on the ratio of the surfaces of the pistons 74 and 77.

As a variant, the free piston is replaced by membranes, as in membrane blowers of known type.

In the embodiment illustrated in FIGS. 6 to 10, a free piston booster 11. The arrows in broken lines represent the movements of gas. The arrow in solid lines represents the movements of the free piston.

The free piston 11 comprises an expansion head 20 and a compression head 22 connected by a shaft. A through opening 24 opens on the one hand into the expansion head 20 on the side opposite the compression head 22 and, on the other hand, into a side wall of the shaft. The first gas line 31 opens into part 21 of the expansion chamber 17 opposite the shaft. As a result, the mouth of the through opening 24 is only in part 21 when the free volume of the compression chamber 23 is maximum. The outlet of the expansion chamber 17 to which the second pipe 32 is connected is located on a side face of the expansion chamber 17 and is not obstructed by the expansion head 20 when the through opening 24 does not open. in the part 21 of the expansion chamber 17. More particularly, the outlet of the expansion chamber is obstructed by the expansion head except in the position of the free piston where the free volume of the compression chamber is minimal.

At the start of the operating cycle of the booster, as illustrated in FIG. 6, the free volume of the compression chamber is intermediate between its extreme values. The pressure in the part 17 of the expansion chamber opposite to the compression chamber 23 is at the value Pb of the downstream network 13. The gas coming from the first pipe 31 enters the intermediate part 21 of the pressure chamber. expansion, at a pressure Pa. The pressure ratio Pa / Pb is greater than the ratio of the areas of the expansion head 20 in part 17 and in part 21. The free piston 11 therefore moves to the left, as illustrated in Figure 7. This movement of the free piston 11 causes the suction of gaseous fluid from the third pipe 33 through the inlet valve 15. When the free volume of the compression chamber 23 is maximum, the through opening 24 opens. on part 21 of the expansion chamber and the gas from the first pipe 31 passes through the expansion head. The pressure in the part 17 of the expansion chamber then reaches Pa, which causes the movement of the free piston 11 towards the compression chamber 23, as illustrated in FIG. 8. This movement obstructs the through opening 24 and compresses the gaseous fluid. present in the compression chamber 23. The compressed gaseous fluid passes through the outlet valve 16 then the fourth pipe 34. When the free volume of the compression chamber 23 is minimal, the part 17 of the expansion chamber is pneumatically connected to the second pipe 32, as illustrated in FIG. 9. Following the increase in the volume of part 17, the pressure in part 17 of the expansion chamber drops to reach the value Pb. The cycle then begins again.

As will be understood from reading the above, this free piston booster 11 operates without an external moving part and as long as there is a sufficient pressure difference between the first pipe and the second pipe.

Claims

1. Device (10, 40, 50, 60) for compressing a gaseous fluid by recovery of energy from expansion of a gas between an upstream gas network (12) under a pressure Pa and a downstream gas network ( 13) under a pressure Pb less than Pa, characterized in that it comprises:

- a pneumatic booster (30, 70, 72) comprising a free piston (11, 74, 76, 77) between an expansion chamber (17, 75) and a compression chamber (23, 78),

- a first gas pipe (31) between the upstream network and an inlet of the expansion chamber,

- a second gas pipe (32) between an outlet of the expansion chamber and the downstream network,

- a third pipe (33) of gaseous fluid to be compressed opening onto an inlet of the compression chamber and

- A fourth pipe (34) of compressed gaseous fluid connected to an outlet of the compression chamber.

2. Device (10, 40, 50, 60) according to claim 1, wherein:

- the free piston (11) comprises an expansion head (20) and a compression head (22) connected by a shaft, a through opening opening out, on the one hand, into the expansion head on the side opposite the head (24 ) compression and, on the other hand, in a side wall of the shaft,

- the first gas line (31) opens into the expansion chamber (17) opposite the shaft and

- the outlet of the expansion chamber to which the second pipe is connected (32) is located on a side face of the expansion chamber and is not obstructed by the expansion head only when the through opening does not open into the relaxation room.

3. Device (40, 60) according to one of claims 1 or 2, which further comprises a valve (45) on the first pipe (31) controlled by a pressure switch (46, 49) positioned downstream of the fourth line (34).

4. Device (40, 60) according to one of claims 1 or 2, which further comprises an all-or-nothing pressure regulator on the first pipe (31), the impulse line of which is placed downstream of the fourth line (34).

5. Device (10, 40) according to one of claims 1 to 4, wherein the third pipe (33) is connected, at its inlet, to the upstream network (12), the gas to be compressed being the gas from the upstream network. .

6. Device (50, 60) according to one of claims 1 to 4, wherein the third pipe (33) is connected, at its inlet, to a reservoir (51, 61) of gas to be compressed.

7. Device (50, 60) according to one of claims 1 to 4, wherein the third pipe (33) is connected, at its inlet, to the atmosphere.

8. Device (10, 40, 50, 60) according to one of claims 1 to 7, wherein the fourth pipe (34) connects the compression chamber (23) to a compressed gas reservoir (14, 44) or to a compressed gas circuit.

9. Device (40, 60) according to one of claims 1 to 8, which further comprises a heat exchanger (41) configured to heat the gas passing through the first pipe (31) and cool the compressed gaseous fluid passing through. the fourth line (34).

10. Device (40, 60) according to one of claims 1 to 9, which further comprises a pressure regulator (47) on the fourth pipe (34).