WO2021130444A1

WO2021130444A1 - Device for high-pressure injection of a wet mixture

Info

Publication number: WO2021130444A1
Application number: PCT/FR2020/052588
Authority: WO
Inventors: Thierry Chataing; Julien ROUSSELY
Original assignee: Syctom L'agence Metropolitaine Des Dechets Menagers; Syndicat Interdepartemental Pour L'assainissement De L'agglomeration Parisienne
Priority date: 2019-12-23
Filing date: 2020-12-22
Publication date: 2021-07-01
Also published as: FR3105207A1; FR3105207B1

Abstract

The invention relates to a device (10) for high-pressure injection of a wet mixture into a supercritical water gasification reactor, the device comprising: - two tubular vessels (101, 102) each comprising a top end (101a, 102a) and a bottom end (101b, 102b); - filling means (200) for selectively filling either of the two vessels (101, 102) with wet mixture at the bottom end (101b, 102b) thereof; - water compression means (300) for selectively compressing, by injecting water into the top end (101a, 102a) of either of the vessels (101, 102), the wet mixture likely to be present in either of the two vessels (101, 102); - means (400) for injecting, into the reactor, the wet mixture likely to be present in either of the two vessels (101, 102) and compressed by the water that has been injected.

Description

Title: HIGH PRESSURE INJECTION DEVICE FOR A WET MIXTURE TECHNICAL FIELD

The invention relates to the field of the reprocessing of organic waste, and in particular to organic waste of little value such as digestates (or co-digestate).

In particular, the present invention relates to a device and a method intended to inject a co-digestate at high pressure, and in particular a pressure greater than 250 bars, or even 300 bars, into a supercritical water gasification reactor (GESC).

STATE OF THE PRIOR ART

The gasification in supercritical water of wet biomass, comprising for example more than 70% water is today well known to man and is widely described in the literature.

This technique makes it possible in particular to treat carbonaceous materials included in effluents such as sludge from purification stations, waste, micro-algae, black liquor from paper mills, or even co-digestates, etc.

In particular, the treatment of these carbonaceous materials by gasification in supercritical water makes it possible to transform the latter into a gaseous mixture, called “syngas”, which comprises in particular the following gaseous species: CH ₄ , H ₂ , CO ₂ , CO.

The implementation of this process nevertheless requires the injection of the effluent under high pressure, and in particular at a pressure greater than 250 bars, or even 300 bars.

However, among the effluents likely to be considered, some, and in particular the co-digestates, exhibit non-Newtonian behavior. In particular, the viscosity of this type of effluent exhibits a high variability as a function of the pressure which is applied to it. The viscosity can in this respect vary between 110 cPoise and 87,000 cPoise.

Thus, piston pumps, although widely used in the fields of construction or oil as described in documents [1], [2] and [3] cited at the end of the description, do not meet the requirements inherent in gasification in supercritical water.

In particular, these pumps do not make it possible to inject effluents, and in particular co-digestates, at pressures greater than 200 bars.

Moreover, the co-digestates, in addition to their non-Newtonian behavior, are subject to water desorption when they are compressed by this type of pump.

Alternatively, conveying / transfer solutions, described in documents [4] and [5] cited at the end of the description, could be proposed. However, like piston pumps, these solutions do not make it possible to achieve the required injection pressures.

Other pressurization and injection devices have been developed for the high pressure injection of fluids such as water and oil. These devices include gear pumps, diaphragm pumps, as well as LEWA valve or ball pumps. These devices are used on an industrial scale for gasification in supercritical water with injection of oxygen for the destruction of liquid chemicals.

However, these devices do not allow fine and optimized metering of an effluent, such as a co-digestate, injected into the gasification reactor in supercritical water. In particular, these pressurization devices use a dilution of the co-digestate which consumes large quantities of water which is difficult to recycle.

Furthermore, the co-digestates comprise a large proportion of solids, in particular abrasive particles which are liable to damage the pressurization devices, and thus lead to long periods of maintenance.

An aim of the present invention is therefore to provide a device for pressurizing a wet mixture loaded with organic matter, for example a co-digestate, making it possible to impose on the latter a pressure of at least 250 bars, or even at minus 300 bars, with a view to its injection into a gasification reactor in supercritical water.

Another object of the present invention is to provide a device for pressurizing the humic mixture that is more robust, and making it possible to limit any failure liable to occur in the presence of solid matter.

Another object of the present invention is to provide a device for pressurizing the humic mixture which allows precise metering of the latter with a view to its injection into a gasification reactor in supercritical water.

Another object of the present invention is to provide a device for pressurizing the humic mixture making it possible to limit the consumption of water. DISCLOSURE OF THE INVENTION

The aims of the invention are, at least in part, achieved by a device for injecting under high pressure a wet mixture comprising organic material, in particular a co-digestate in a supercritical water gasification reactor, the device comprising:

- two tubular shaped reservoirs each comprising an upper end and a lower end, preferably said reservoirs having no piston;

a filling means making it possible to selectively fill one and the other of the two reservoirs with a wet mixture at their lower end;

a water compression means making it possible to compress selectively, by injecting water at the level of the upper end of one or the other of the reservoirs, the wet mixture likely to be present in one and the other other of the two tanks;

a means for injecting, into the reactor, the wet mixture capable of being present in one and the other of the two reservoirs, and compressed by the injected water.

The device according to the present invention thus makes it possible to impose a high pressure, in particular a pressure greater than 250 bars, or even greater than 300 bars, on the wet mixture without circulation of the latter in the means of compression. The compression means are thus preserved from any damage liable to be induced by the presence of solids in the wet mixture.

According to one embodiment, the filling means comprises a filling pump as well as two filling conduits, each associated with a filling valve valve, intended to inject, selectively, the wet mixture into one or the other. other of the two tanks.

According to one embodiment, the compression means comprises a compression pump as well as two compression conduits, each associated with a compression valve, intended to selectively inject high pressure water into one and the other. other of the two tanks.

According to one embodiment, said device further comprises means for recycling the water injected at high pressure into one and the other of the two reservoirs, and provided with a recycling pipe intended to take said water. at the upper end of said reservoirs.

The recycling means thus makes it possible to limit water consumption.

According to one embodiment, the recycling duct is arranged to impose recirculation of the water in the compression means.

According to one embodiment, the recycling means comprises two recycling valves making it possible to take water selectively from one and the other of the reservoirs.

According to one embodiment, the recycling means comprises a buffer tank intended to store the water taken from one and the other of the tanks.

According to one embodiment, the compression means is arranged to take the water stored in the buffer tank with a view to injecting it under pressure into one or the other of the tanks.

According to one embodiment, the reservoirs each form a coil.

According to one embodiment, the reservoirs form a tube of length L and of diameter D, and so that the ratio of the length L to the diameter D is greater than 30. According to one embodiment, the diameter D is less than 500 mm, or even less than 250 mm.

The invention also relates to an installation for gasification with supercritical water of a wet mixture comprising organic matter, in particular a co-digestate, which comprises:

- a supercritical water gasification reactor

- The injection device according to the present invention.

The invention also relates to a method for injecting a wet mixture comprising organic material, in particular a co-digestate, at high pressure into a supercritical water gasification reactor using the injection device according to the present invention. , the method comprising filling / injection cycles executed so as to inject into the reactor, and from the reservoirs, the wet mixture in an essentially continuous manner and at high pressure, each filling / injection cycle comprising a phase of filling in mixture wet from one or the other of the reservoirs, followed by a phase of injection, into the reactor, of said wet mixture subjected to the high pressure imposed by the water injected by the compression means.

According to one embodiment, during the filling phase of one of the reservoirs, the water likely to be present in the latter is discharged.

According to one embodiment, the water evacuated during the filling phase is reinjected into the compression means.

According to one embodiment, the injection phase comprises the compression of the wet mixture injected during the filling phase with the water injected by the compression means, at a pressure greater than 250 bars, or even greater than 300 bars. , and injecting the wet mixture into the reactor via the injection means.

According to one embodiment, the injection phase comprises the complete injection of the wet mixture present in the reservoir concerned, as well as a fraction of the water injected by the compression means into said reservoir. According to one embodiment, as soon as one of the reservoirs is in the filling phase, the other is in the injection phase.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages will appear in the following description of a device for injecting a wet mixture comprising organic material at high pressure according to the invention, given by way of nonlimiting examples, with reference to accompanying drawings in which:

FIG. 1 is a schematic representation of a high pressure co-digestate injection device according to a first embodiment of the present invention;

FIG. 2 is a schematic representation of a high pressure co-digestate injection device according to a second exemplary embodiment of the present invention;

FIG. 3 is a schematic representation of the implementation of the injection method according to the present invention, in particular, FIG. 3 represents the phase of filling the first reservoir and the phase of injection of the co-digestate, present in the second tank, in the reactor;

FIG. 4 represents the phase of injection, towards the reactor, of the co-digestate as well as a fraction of the water present in the second tank;

FIG. 5 is a schematic representation of the implementation of the injection method according to the present invention, in particular, FIG. 3 represents the phase of filling the second reservoir and the phase of injection of the co-digestate, present in the first tank, in the reactor;

FIG. 6 represents the phase of injection, towards the reactor, of the co-digestate as well as a fraction of the water present in the first tank.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

For the sake of clarity, only the elements which are useful for understanding the embodiments of the invention have been shown and are detailed. In particular, the implementation of the gasification in supercritical water is not detailed. In FIG. 1, one can see a first embodiment of a device 10 for injecting at high pressure a humic mixture comprising organic material into a reactor 11 for high pressure gasification.

The wet mixture comprising organic material intended to be pressurized can in particular comprise a “co-digestate”.

In this regard, the remainder of the description refers only to a co-digestate. It is however clear that the invention is not limited to this single aspect. Thus, any wet mixture loaded with organic matter, and possibly exhibiting non-Newtonian behavior, can also be considered.

In particular, said mixture may comprise waste from agriculture, in particular manure.

The term “co-digestate” is understood to mean a mixture of digestate and sewage plant sludge.

By “digestate” is meant a residue from the methanization process of natural organic materials or organic waste products.

In other words, a co-digestate is a wet mixture (containing water) of organic matter and solid matter, and more particularly of inorganic solid matter.

The term “high pressure” is understood to mean a pressure greater than 250 bars, or even greater than 300 bars.

The co-digestate according to the terms of the present invention can have a Higher Calorific Value (or “PCS”) of less than 12 Megajoules / kilogram.

The injection device 10 comprises two so-called reservoirs, respectively, first reservoir 101 and second reservoir 102.

Each of the two reservoirs has a tubular shape and extends between an upper end 101a, 102a and a lower end 101b, 102b.

More particularly, the reservoirs 101 and 102 can form a tube of length L and diameter D, and so that the ratio of the length L to the diameter D is greater than 30. For example, the diameter D is less than 500 mm. see less than 250 mm. The tanks 101 and 102 can also include 316L stainless steel.

Still by way of example, the wall of the reservoir may have a thickness of between 5 mm and 15 mm, in particular 7.11 mm. Furthermore, the length L of a tank may be between 3 m and 15 m, in particular be equal to 4 m.

The two reservoirs 101 and 102 can advantageously be devoid of a movable piston.

The injection device 10 also comprises a filling means 200 which makes it possible to fill in co-digestate both the first 101 and the second 102 reservoir.

The filling of both of the first 101 and of the second 102 reservoir is carried out in particular at the level of the lower end of each of the reservoirs 101 and 102.

In this regard, the filling means 200 may comprise a filling pump 203, intended to take the co-digestate from a co-digestate tank 206.

The filling pump may for example be a pump of the NOV brand and of the C23BC11RMA type.

The filling means 200 can also comprise a first filling duct 204 and a second filling duct 205 in which the co-digestate taken by the filling pump 203 is conveyed to, respectively, the first reservoir 101 and the second reservoir 102.

In other words, the first filling duct 204 and the second filling duct 205 connect the filling pump 203 and the lower end 101b, 102b, respectively, of the first reservoir 101 and of the second reservoir 102.

The first filling duct 204 and the second filling duct 205 are also provided, respectively, with a first filling valve 201 and a second filling valve 202.

The injection device 10 also comprises a water compression means 300 making it possible to compress selectively, by injecting water into the water. level of the upper end 101a, 102b, of one or the other of the first reservoir 101 and of the second reservoir 102, the co-digestate capable of being present in either of the two reservoirs.

In this regard, the water compression means 300 may include a compression pump 303, as well as a first compression duct 304 and a second compression duct 305 in which high pressure water exiting from the compression pump. 303 is routed to, respectively, the first reservoir 101 and the second reservoir 102.

The compression pump 303 is for example a diaphragm metering pump associated with LEWA brand ball valves.

In other words, the first compression duct 304 and the second compression duct 305 connect the compression pump 303 and the high end 101a, 102a, respectively, of the first reservoir 101 and of the second reservoir 102.

The first compression duct 304 and the second compression duct 305 are also provided, respectively, with a first compression valve 301 and a second compression valve 302.

The injection device 10 also comprises an injection means

400.

In particular, the injection means 400 is intended to allow the injection, into the reactor 11, of the co-digestate likely to be present in one and the other of the two reservoirs, and compressed by the injected water. by the compression means 300.

In this regard, the injection means 400 may comprise a first injection duct 404 and a second injection duct 405 in which the co-digestate under high pressure exiting from the lower end 101b, 102b of one or more. the other from the first tank 101 and from the second tank 102 is routed to the reactor.

In other words, the first injection duct 404 and the second injection duct 405 connect the reactor 11 to the lower end 101b, 102b, respectively, of the first tank 101 and of the second tank 102. The first injection duct 404 and the second injection duct 405 are also provided, respectively, with a first injection valve 401 and with a second injection valve 402.

The injection device 10 can also comprise a means 500 for recycling the water injected at high pressure into both of the first tank 101 and of the second tank 102. The recycling means 500 is in particular provided with a recycling pipe 503 intended to take the water injected into one and the other of the first reservoir 101 and of the second reservoir at their upper end 101a, 102a.

More particularly, the recycling means 500 comprises a first recycling valve 501 and a second recycling valve 502 making it possible to selectively take water from the first tank 101 and from the second tank 102.

Advantageously, the recycling duct 500 can be arranged to impose recirculation of the water taken from the water compression means 300.

This arrangement thus makes it possible to limit the consumption of water and its reprocessing.

According to an advantageous embodiment, the recycling means comprises a buffer tank 506 intended to store the water taken from one and the other of the tanks. Still according to this embodiment, the water compression means 300 is arranged to take the water stored in the buffer tank 506 with a view to injecting it under pressure into one or the other of the first tank 101 and the second. tank 102.

FIG. 2 illustrates a second exemplary embodiment of a device 10 for injecting a co-digestate at high pressure into a reactor 11 for high pressure gasification.

This second example differs from the first example in that the first reservoir 101 and the second reservoir 102 form a coil. This arrangement makes it possible to increase the length L of each of the reservoirs while limiting the space occupied by the injection device 10. The invention also relates to an installation for gasification with supercritical water of a co-digestate which comprises the reactor 11 for gasification with supercritical water, and the injection device 10 according to the present invention.

The invention also relates to a method for injecting a co-digestate at high pressure into the supercritical water gasification reactor using the injection device 10.

This method comprises in particular filling / injection cycles executed so as to inject into the reactor, and from the first tank 101 and from the second tank 102, the co-digestate in an essentially continuous manner and at high pressure.

In this regard, each filling / injection cycle comprises a phase of filling the first tank 101 or the second tank 102 with co-digestate, followed by a phase of injecting, into the reactor 11, said co-digestate subjected to the process. high pressure imposed by water injected by the water compression means 300.

In other words, as soon as a filling phase is performed at one of the first and second reservoir, an injection phase is performed at the other of the first and second reservoir. This sequence makes it possible to ensure a continuous injection of co-digestate into the reactor.

Thus, as illustrated in FIG. 3, the phase of filling the first tank comprises the withdrawal, by the filling pump, of co-digestate from the co-digestate tank 206. The opening of the first filling valve 201 and the closing of the second filling valve 202, makes it possible to direct the co-digestate taken by the filling pump into the first tank 101. The water likely to be present in the first tank 101 is also discharged at the level from its upper end 101a in the recycling means 500. This evacuation of the water is in particular permitted by the opening of the first recycling valve 501 while the second recycling valve remains closed.

Simultaneously (FIG. 3) with the filling phase of the first reservoir 101, an injection phase is carried out from the second reservoir 102. in particular, the injection comprises the transfer of the co-digestate present in the second reservoir 102 to the reactor 11.

This phase notably implements the water compression means 300 which injects water at high pressure at the upper end 102a of the second reservoir 102. During this phase, the second valve of 302 is open while the first compression valve 301 remains closed.

The high pressure injection of the water is furthermore carried out by means of the compression pump 303.

Thus, during this injection phase, the pressure exerted by the injected water makes it possible to impose a high pressure on the co-digestate present in the second reservoir 102. The opening of the second injection valve 402, both in keeping the first injection valve closed, allows the co-digestate under high pressure to flow through the second injection pipe into the reactor 11.

Thus, the water injected into the second reservoir forms a water piston. The very nature of the co-disgestate, and in particular its non-Newtonian behavior, limits the miscibility of the water piston and said co-disgestate. A slight miscibility, without consequence on the co-disgestat, can be observed at the level of the interface formed between the water piston and the co-disgestat. In addition, the consideration of a small internal diameter D of the reservoir, and in particular less than 250 mm, limits, or even prevents, any infiltration of water between the internal wall of the reservoir concerned and the co-digestate.

The immiscibility between the water and the co-digestate eliminates the need for the presence of a mobile piston.

In a particularly advantageous manner, the water evacuated from the first reservoir during its filling phase can be injected into the second reservoir 102. This aspect advantageously makes it possible to limit the consumption of water.

The injection phase continues until complete injection of the co-digestate present in the second reservoir 102. Advantageously, and as illustrated in FIG. 4, after the complete injection of the co-digestate present in the second tank 102, a fraction of the water it contains is also injected into the reactor 11. This procedure makes it possible to rinse the second injection valve 402, and to entrain any solid material liable to be stuck at said valve.

At the end of the injection phase from the second tank, the filling phase of the latter is implemented, while the co-digestate present in the first tank is injected into the reactor during a phase of injection.

Thus, as illustrated in FIG. 5, the phase of filling the second tank comprises the withdrawal, by the filling pump, of co-digestate from the co-digestate tank 206. The opening of the second filling valve 202 and the closing of the first filling valve 201, makes it possible to direct the co-digestate taken by the filling pump into the second tank 102. The water likely to be present in the second tank 102 is also discharged at the level of its upper end 102a in the recycling means 500. This evacuation of the water is in particular permitted by the opening of the second recycling valve 502 while the first recycling valve remains closed.

Simultaneously with the filling phase of the second reservoir 102, an injection phase is performed from the first reservoir 101. In particular, the injection comprises the transfer of the co-digestate present in the first reservoir 101 to the reactor 11. .

This phase notably implements the water compression means 300 which injects water at high pressure at the high end 101a of the first reservoir 102. During this phase, the first valve of 301 is open while the second compression valve 302 remains closed.

Thus, during this injection phase, the pressure exerted by the injected water makes it possible to impose a high pressure on the co-digestate present in the first reservoir 101. The opening of the first injection valve 401, both in keeping the second injection valve closed, allows the co-digestate under high pressure to flow through the first injection pipe into the reactor 11. Thus, the water injected into the first reservoir forms a water piston. The very nature of the co-disgestate, and in particular its non-Newtonian behavior, limits the miscibility of the water piston and said co-disgestate. A slight miscibility, without consequence on the co-disgestate, can be observed at the level of the interface formed between the water piston and the co-disgestate. In addition, the consideration of a small internal diameter D of the reservoir, and in particular less than 500 mm, or even less than 250 mm, limits, or even prevents, any infiltration of water between the internal wall of the reservoir concerned and the co-digestate.

In a particularly advantageous manner, the water discharged from the second reservoir during its filling phase can be injected into the first reservoir 102. This aspect advantageously makes it possible to limit the consumption of water.

The injection phase continues until complete injection of the co-digestate present in the first reservoir 101. Advantageously, and as illustrated in FIG. 6, at the end of the complete injection of the co-digestate present in the first tank 101, a fraction of the water that it contains is also the reactor 11. This procedure makes it possible to rinse the first injection valve 401, and to entrain any solid material liable to be stuck at the level of said valve.

The injection device according to the present invention is thus arranged to prevent any passage of solid material into the compression pump. The latter is thus protected from abrasion due to the passage of the solid material included in the co-digestate.

Furthermore, the injection device limits, or even prevents, any dilution of the co-digestate with the water injected into one or the other of the two reservoirs. This thus results in a better dosage of the co-digestate injected into the reactor. REFERENCES

[1] EP 2002121 B1;

[2] EP 0991864;

[3] EP1884656; [4] KR100885902;

[5] CN105626627;

Claims

1. Device for injecting (10) under high pressure a wet mixture comprising organic material, in particular a co-digestate, into a supercritical water gasification reactor, the device comprising:

- two reservoirs (101, 102) of tubular shape each comprising an upper end (101a, 102a) and a lower end (101b, 102b);

- a filling means (200) making it possible to selectively fill with a wet mixture one and the other of the two reservoirs (101, 102) at their lower end (101b, 102b);

- a water compression means (300) making it possible to compress selectively, by injecting water at the level of the upper end (101a, 102a) of one or the other of the reservoirs (101, 102), the mixture wet likely to be present in either of the two reservoirs (101, 102);

- A means for injecting (400), into the reactor, the wet mixture capable of being present in one and the other of the two reservoirs (101, 102), and compressed by the injected water.

2. Injection device (10) according to claim 1, wherein the filling means (200) comprises a filling pump (203) as well as two filling conduits (204, 205), each associated with a valve valve. filling (201, 202), intended to inject, selectively, the wet mixture into one or the other of the two reservoirs (101, 102).

3. Injection device (10) according to claim 1 or 2, wherein the water compression means (300) comprises a compression pump (303) and two compression conduits (304, 305), each associated with a compression valve (301, 302), intended to selectively inject high pressure water into one and the other of the two reservoirs (101, 102).

4. Injection device (10) according to one of claims 1 to 3, wherein said device further comprises a recycling means (500) of the water injected at high pressure into one and the other of two reservoirs (101, 102), and provided with a recycling pipe intended to draw off said water at the level of the upper end (101a, 102a) of said reservoirs (101, 102).

5. An injection device (10) according to claim 4, wherein the recycling duct is arranged to impose recirculation of the water in the water compression means (300).

6. An injection device (10) according to claim 4 or 5, wherein the recycling means (500) comprises two recycling valves making it possible to take water selectively from one and the other of the reservoirs (101, 102).

7. Injection device (10) according to one of claims 4 to 6, wherein the recycling means (500) comprises a buffer tank (506) for storing the water taken from one and the other. reservoirs (101, 102).

8. An injection device (10) according to claim 7, wherein the water compression means (300) is arranged to take the water stored in the buffer tank (506) with a view to injecting it under pressure into the water. either of the reservoirs (101, 102).

9. An injection device (10) according to one of claims 1 to 8, wherein the reservoirs (101, 102) each form a coil.

10. Injection device (10) according to one of claims 1 to 8, wherein the reservoirs (101, 102) form a tube of length L and diameter D, and so that the ratio of the length L to diameter D is greater than 30.

11. Injection device (10) according to claim 10, wherein the diameter D is less than 500 mm or even less than 250 mm.

12. Installation for gasification in supercritical water of a wet mixture comprising organic matter which comprises:

- a supercritical water gasification reactor

- the injection device (10) according to one of claims 1 to 11.

13. A method of injecting a wet mixture comprising organic material, in particular a co-disgestate, at high pressure in a supercritical water gasification reactor using the injection device (10) according to one of the claims 1 to 11, the method comprising filling / injection cycles executed so as to inject into the reactor, and from the reservoirs (101, 102), the wet mixture essentially continuously and at high pressure, each filling cycle / injection comprising a phase of filling with a wet mixture of one or the other of the reservoirs (101, 102), followed by a phase of injection, into the reactor, of said wet mixture subjected to the high pressure imposed by the water injected by the water compression means (300).

14. The injection method according to claim 13, wherein during the filling phase of one of the reservoirs (101, 102), the water likely to be present in the latter is discharged.

15. The injection method of claim 14, wherein the water discharged during the filling phase is reinjected into the water compression means (300).

16. The injection method according to one of claims 13 to 15, wherein the injection phase comprises compressing the wet mixture injected during the injection. filling phase with the water injected by the water compression means (300), at a pressure greater than 250 bars, or even greater than 300 bars, and the injection of the wet mixture into the reactor via the injection means ( 400).

17. The injection method according to claim 16, wherein the injection phase comprises the complete injection of the wet mixture present in the reservoir concerned, as well as a fraction of the water injected by the water compression means ( 300) in said reservoir.

18. Injection method according to one of claims 13 to 17, wherein when one of the reservoirs (101, 102) is in the filling phase, the other is in the injection phase.

19. An injection method according to one of claims 13 to 18, wherein the wet mixture is a non-Newtonian fluid.