WO2017089372A1 - Method and device for treatment by supercritical fluid with passive gravity pumping - Google Patents

Abstract

A device for treatment by dense fluid, for example a fluid in the supercritical state, is described, having: a) a treatment chamber (14) that is intended to receive components to be treated and is provided with means (15) for putting the chamber into fluidic communication with the outside atmosphere, b) means for supplying said chamber with dense fluid, for example a fluid in the supercritical state, having at least one 1st reservoir (6), c) a 2nd reservoir (20) which has a lower part and an upper part and has means for connecting, from a fluidic point of view, said lower part to an upper part of the 1st reservoir (6), this 2nd reservoir (20) also having an outlet that is connected fluidically to an inlet of the treatment chamber (14), d) means (6₁) for supplying this 2nd reservoir with fluid in the liquid state.

Description

 METHOD AND DEVICE FOR SUPERCRITICAL FLUID TREATMENT

 WITH PASSIVE PUMPING GRAVITAI RE

DESCRIPTION TECHNICAL FIELD AND STATE OF THE PRIOR ART

The invention relates to processing techniques, in particular extraction, for example cleaning, parts or objects by implementation of a dense fluid, for example super critical, including carbon dioxide.

 A cleaning technique is known from WO 02/32593. A known device for implementing such a technique will be described in connection with the schematic representation of FIG.

 This device is fed with a liquefied gas, which comes for example from a reserve, or bottle, 2, in which it is maintained at a temperature of, for example, -20 ° C.

 This reserve 2 is used to feed a storage chamber 6, which stores both gaseous gas and liquefied gas, via a pump 3 or a filling compressor and a valve 6i. In this chamber, the gas is heated by means of heating 7, which will increase its temperature, for example to 20 ° C, and bring it to a pressure of several tens of bars, for example about 60 bar .

Liquefied gas, taken from this chamber 6 by means of a valve 63, can then be carried, by means 8, under thermodynamic conditions allowing it to be used as a cleaning fluid in the enclosure of cleaning 14, also called autoclave. In particular, the means 8 may comprise pumping means 10 and heating means 12. In the case where the fluid is C0 ₂ , the pump 10 can carry the fluid from the reserve 6 to a pressure greater than 73 85 bar, and the heating means 12 can raise the temperature of the fluid to a value greater than 31 ° C, these conditions ensuring the fluid a super critical state. In the autoclave, the fluid may be used in accordance with the teaching of WO 02/32193. The autoclave 14 is provided with a door 15 which will allow to introduce the parts to be cleaned. After closing the door, the fluid is introduced under pressure, at about 120 bar, and the parts are cleaned by the action of the fluid.

During a cleaning cycle, the fluid is then evacuated, expanded by expansion means 16 (generally comprising a control valve 16 ₂ and a valve 16i), and then sent to means 18 forming a separator, which will make it possible to separating the gas from the particles and soils that have been recovered during cleaning and the gas is charged.

 The gas thus treated can then be fed to liquefaction means 19 and then stored again in liquid form in enclosure 6.

In such a device, particularly when the gas is C0 ₂ , the filling pump 3 can pose a cavitation problem because the gas that feeds it can be almost gaseous. If a compressor is used instead of this pump, a vaporization step is also necessary, which requires an exchanger at the compressor inlet.

 Moreover any pump, including the filling pump 3 (or possibly compressor), requires maintenance and a risk of failure.

 The device is therefore complex and expensive in maintenance. There is therefore the problem of finding a simpler structure and maintenance device.

 In addition, a cleaning cycle implemented with this type of device is too long for implementation on a truly industrial scale.

 During a cleaning cycle, after introduction of the parts to be cleaned in the autoclave 14 and then closing the door 15 thereof, but before the start of the cleaning cycle, gas is introduced into the autoclave at a pressure about a few bars.

This gas comes from the enclosure 6. For this purpose, a valve 6 ₂ is disposed on a path defined by a conduit 9 which connects an upper portion of the enclosure 6 and directly the means 14. If it is desired to heat the gas before introduction into means 14, it is possible to connect the means 9 between the pump 10 and the heating means 12. It is also possible to connect the means 9 directly to the means 27.

This step allows, when the dense fluid gas is then introduced, under pressure, from the means 8, to prevent it from being under conditions that can lead to the formation of a block of ice (this is the phenomenon, in the case of carbon dioxide, formation of dry ice, in fact, the triple point of CO ₂ is at -56 ° C, 5 bar.), which is to be avoided because this ice can be very difficult to eliminate quickly.

 But this technique leads:

 - A risk of cavitation of the pump 10: due to the initial consumption of gas, the pressure, but also the temperature, of the chamber 6 have decreased, which can induce these cavitation problems; to limit them to the maximum, the volume of the enclosure 6 must be as large as possible, which is expensive, or the filling of the enclosure 14 must be slow, which is not acceptable,

 - A waste of time, because the gas thus consumed must be reintroduced into the system, for example by supplying the chamber 6 from the reserve 2; the heating step with the means 7 implies a duration which increases the duration of a cycle of operation of the machine.

 Therefore, from the point of view of the duration of implementation of a cycle, as energy consumption, such a known device can not be implemented on a truly industrial scale.

 There is also the problem of finding a new method and a new injection device, and / or treatment, which is less expensive and allows a cleaning cycle faster than known devices and methods.

The same problem arises for the treatment of a part, for example a treatment for the implementation, more generally, of an extraction process or for a sterilization process. STATEMENT OF THE INVENTION

The invention aims to solve these problems.

 According to the invention a dense fluid treatment device, for example a fluid in the supercritical state, comprises:

 a) a treatment chamber, intended to receive parts to be treated, and provided with means for placing in fluid communication the chamber and the external atmosphere,

b) means, or a circuit, supply of said enclosure dense fluid, for example a fluid in the supercritical state, comprising at least one tank ^1, c) a ^2nd tank, having a lower portion and an upper portion, and having means or a circuit for connecting, from the fluid point of view, said lower portion to a portion of ¹ tank, preferably its upper part which is located at a level below the lower part the ^2nd tank, ^2nd reservoir further having an output, fluidly connected to an inlet of the treatment chamber,

d) means, or a circuit for supplying the ^2nd reservoir in fluid in the liquid state. This supply circuit comprises for example at least one valve and a conduit, which can be connected to a reservoir or a liquefied gas reserve.

 Here and in the following, the expression "fluidic communication", which applies to 2 volumes, means that a fluid can circulate, or flow, from one volume to another. The means for setting fluid communication are also means for interrupting this fluid communication, that is to say to stop any possibility of fluid flow from one volume to another.

The ^2nd tank can be supplied with fluid in the liquid state without pumping means. The invention therefore makes it possible, in a device for treating a dense fluid, for example a fluid in the supercritical state, to have means for forming a reserve of gas and liquid, supplied by a gas source, without means of pumping.

The invention provides, in a dense fluid treatment machine, means for forming a gas reservoir, on the one hand in the gaseous state and, on the other hand, in the liquid state. Then, gas, in the gaseous state, can be sent, from this reservoir, to the treatment chamber, or autoclave, and gas, in the liquid state, can be sent to the ^1st tank.

The supply means 2 ^nd reservoir may comprise at least one the ^first conduit and the valve ^era.

The bottom of the ^2nd container can be connected by means including at least one conduit and a 2 ^nd 2 ^nd valve part, preferably greater than, ¹ tank.

Such a device may further comprise means for thermally isolating said ^1st conduit and / or said ^2nd conduit.

Means are preferably provided to connect an upper portion of ^2nd tank and said upper part of the tank ^1, said means comprising for example at least one conduit and a 3 ^rd 3 ^rd valve. These means may be external to the ^2nd tank.

Means may be provided to heat or maintain at constant temperature said 3 ^rd conduit.

In one embodiment, the supply means 2 ^nd reservoir further include means for storing a liquid fluid.

The means for connecting, from the fluid point of view, the ^2nd tank (preferably an upper part or top of this ^2nd tank), to an input of the processing chamber preferably comprise a ^4th conduit and a 4 ^the valve.

The supply means 2 ^nd reservoir can be fluidly connected to means for connecting, from the fluid point of view, the bottom of the ^2nd tank part, preferably greater than, ¹ tank. For example, a duct is connected on one side to a tank or a supply of liquefied gas and secondly to a duct connecting the bottom of the ^2nd tank part, preferably greater than, ¹ tank.

According to one embodiment, the storage means comprise a wall internally coated with thermal insulation means. They may further comprise means for detecting a level, or level sensor, of liquid contained in the storage means. The invention also relates to a process for preparing a supercritical fluid treatment cycle using a device as described above.

 The invention also relates to a process for preparing a supercritical fluid treatment cycle, preferably using a device as described above, in which:

a) the ^2nd tank is supplied, from a source of liquid gas supply with a gas mixture, in gaseous form, and gas in liquid form, b) then, at least part of the gas thus stored in the ^2nd tank, in gaseous form, is sent to the treatment chamber,

c) and at least a portion of the gas, thus stored in the ^2nd tank, in liquid form, is sent to the ^1st tank.

 Step a) can be performed without the action of a pump for pumping fluid from the liquid gas supply source.

Before step a), a preliminary step may be provided to deliver gas stored in the ^2nd tank in gaseous form, to the treatment chamber, reducing the pressure in the ^2nd tank to a value less than the pressure of the liquid gas supply source.

During step c), at least part of the gas stored in the 2 'th tank, in liquid form, can be sent to the tank ^1; before step c), u step of pressure equalization of the 2 ^nd and reservoir tank ¹ may be provided.

 tank can be connected to a gas outlet of the treatment chamber.

The gas supplied during step a), the ^2nd tank can be produced by vaporization of liquefied gas.

 The invention also relates to a process for treating a workpiece, by supercritical fluid, comprising:

 a process for preparing a treatment cycle, as described above,

- Then the completion of a treatment cycle, with, during at least part of the cycle, feeding the chamber, with super critical gas. During processing, at least part of a gas, out of the enclosure, can be sent to the ¹ tank.

In a process for preparing a treatment, or a dense fluid treatment cycle, for example supercritical, using a device according to the invention, in particular of the type described above, the ^2nd storage means are fed with a gas mixture, in gaseous form, and gas, in liquid form.

In a preliminary phase, some gas may have been introduced into the treatment chamber, during or before the introduction of gas - liquid mixture in the ^2nd fluid storage means. This gas can come from the ^2nd storage means.

 A dense or supercritical fluid cleaning method according to the invention may comprise:

 a process for preparing a treatment, or a treatment cycle, as described above,

 - Then carrying out a treatment cycle, with, during at least part of the cycle, the supply of said storage means, by dense gas, for example super critical.

 The invention also relates to a treatment method, for example cleaning, by dense fluid, for example super-critical, implementing a device according to the invention, in particular of the type as described above.

 In a method according to the invention, the part to be cleaned may be at least partly made of a metallic material, and / or of a metal alloy, and / or of ceramic material, and / or of a semiconductor material, and or in a textile material and / or a natural material.

 A method according to the invention can make it possible to implement various treatments, for example an extraction treatment, for example cleaning or degreasing, or debinding, or sterilization.

The invention also relates to a computer program comprising the instructions for implementing a method according to the invention, in particular as described above. The invention also relates to a data carrier, readable by a computer system, comprising the data, in encoded form, for implementing a method according to the invention, in particular as described above.

 The invention also relates to a software product comprising a program data support means, readable by a computer system, for implementing a method according to the invention, in particular as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a supercritical fluid cleaning machine, of known type,

 FIG. 2 is a diagram of an embodiment of a supercritical fluid cleaning machine, according to the invention,

 FIG. 3 represents an exemplary embodiment of a passive pumping reservoir, according to the invention,

 - Figure 4 is a schematic representation of the control means of a machine according to the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

FIG. 2 shows an embodiment of a machine according to the invention.

 Numerical references identical to those of FIG. 1 denote identical or corresponding elements.

In particular, this machine comprises a storage chamber 6 (or main storage chamber of the system, also called ^1st tank in the following), designed to store liquefied gas, several tens of bars, for example 60 bar. This enclosure may be provided with means for measuring the temperature and / or the pressure and / or the level of liquid that it contains. It can be supplied with liquid from a reserve volume 2, which has for example the shape of a tank (which contains gas at, for example, -20 ° C. and 20 bar), at which the device can be connected via a conduit 29 (or 1 ^st conduit). This reservation is communicated with the storage chamber 6 via at least one valve 6i (or valve ^AD) but without filling pump. In the illustrated example, a second valve 20i (or ^2nd valve) is disposed at the entrance of this chamber.

 Such a device thus avoids the maintenance and maintenance problems, already mentioned above, related to the use of such a pump.

An initial filling of the enclosure 6 can be achieved in the following manner. Liquefied gas, which comes from the volume of the reserve 2, is introduced by opening the inlet valves 6i and 20i, at the pressure and at the temperature of the reserve 2, for example 20 bars and -20 ° C. It cools the wall of the enclosure, which leads to a vaporization of a portion of this fluid. When the liquid level in the chamber 6 is considered sufficient, the valves 6i and 20i are closed. An exhaust valve 6 ₄ may be provided: if the pressure referred to in the enclosure 6, for example 20 bars, is reached before sufficient filling by the liquid, gas may be released by opening this valve 6 ₄ . Then when the liquid level is sufficient, valves 6 ₄ , 20 1 and 6 ₁ can be closed.

 Such an initial filling of the tank 6 can be exceptional: for example, it is performed at the first start of the machine, or after a major operation (after a certain period of operation).

The heating means 7, comprising for example at least one resistor, then make it possible to increase the temperature and pressure conditions in this enclosure 6, for example (for CO ₂ ) at + 20 ° C. and 60 bars, or more generally, at a temperature between 15 ° C and 30 ° C, and at pressure for example between 50 bar and 90 bar or even greater than 90 bar.

The autoclave 14, or cleaning chamber, accommodates the parts to be cleaned. This chamber is provided with a door 15, through which the parts can be introduced into the enclosure, then, after cleaning, extracted from the enclosure. The autoclave may also be provided with a vent, or vent pipe, and a valve 14 ₂ .

Means for possibly moving this autoclave, as well as means for accommodating baskets that will contain parts to be cleaned, are described in WO 02/32593. Means 8, for example comprising a pump 10 and means 12 for heating (for example one or more resistors or one or more heat exchangers) make it possible to bring the fluid, taken from the chamber 6, via a valve 63, into thermodynamic conditions allowing it to be used as a dense cleaning fluid in the cleaning chamber 14. In the case where the fluid is C0 ₂ , and if one wants to work in super critical conditions, the pump 10 can wear the fluid from the reserve 6 at a higher pressure 73.85 bars, and the heating means 12 can raise the temperature of the fluid to a value greater than 31 ° C, these conditions then provide the fluid a so-called super-critical state . The fluid flows in the conduit 27, the valve 14i opening the access of the supercritical fluid flow to the autoclave 14.

 Means 16 (in this example: a valve I61 and a control valve I62) make it possible to relax the gas leaving the autoclave 14.

 A separator 18, or means 18 forming a separator, make it possible to separate the gas from the impurities it carries and which result from a preceding or ongoing cleaning operation.

 The means 19 are liquefaction means, preferably by cooling by heat exchange. This liquefier makes it possible to reintroduce liquid into the enclosure 6. According to one embodiment, these means may in particular comprise one or more heat exchangers.

The device further comprises means 20 for storage (or storage tank or enclosure, also called 2 ^nd tank in the following) which will form, as explained below, a passive pump. These means 20 are different from the enclosure and means 6. These means 20 may be provided with means, or at least one sensor, for measuring the pressure and / or the temperature of the fluid they contain and / or the level of liquid they contain. These means 20 are located higher than the storage means 6: the lower or lower point of this reservoir 20 (or rather, its internal volume), following the vertical of the place where this reservoir 20 is located, is at a height h not zero relative to the highest point of the tank 6 (or rather, its internal volume). These means 20 are arranged in parallel with the supply conduit 27 which makes it possible to supply the enclosure 14 with dense fluid, possibly super-critical. The lower part (in the sense above) of these means 20 is connected, via a conduit 23 (or 2 ^nd conduit) provided with the valve 20i, to the storage means 6.

Given the relative position of the volumes 6 and 20, this will allow a flow, by gravity, the liquid contained in the reservoir 20 to the reservoir 6. During a cleaning process, the latter may be fed with liquid , in particular from the ^2nd tank 20. the conduit 23 which connects the enclosure 20 to the enclosure 6 preferably enters the bottom of the enclosure 20 so as to empty all the liquid contained in the chamber 20.

 The connection 29 which brings fluid to the reservoir 20 could be connected anywhere in the enclosure 20. But it is preferable to connect this inlet to the connection or to the conduit 23, as close as possible to the valve 20i so as to cooling (thanks to the cold fluid from the source 2) the connection 23. The latter is preferably thermally insulated so as to maintain the fluid it contains (especially for transfer to the reservoir 6) to the liquid state as much as possible.

 The valve 20i can be placed as low as possible on the conduit 23 to maximize the height of liquid fluid that can be transferred from the reservoir 20 to the reservoir 6.

The entrance to these means 20 is connected via conduit ¹ 29 provided with the valve 6i, the two source of liquefied gas. This input is preferably done at the lowest level of the 2 ^nd line 23 to minimize the number of nozzles in the means 20 and also to set the greater part of the conduit 23 to the tank temperature 2 of liquid storage and fill fluid liquid.

The upper part of the means 20 is connected via a conduit 28 (or conduit 3 ^rd) with a 2Ο3 valve (valve or ^3rd), the top of the tank 6 storage. The conduit 28 may be heated or thermostated, for example by a resistor or heating tape, in the portion between the reservoir 6 and the valve 2Ο3 to not condense gas therein. Between this valve 2Ο3 and the means 20 the portion 28i of the conduit 28 is preferably descending, to avoid any siphon effect, so as not to create accumulation of liquid fluid. This portion, between this valve 2Û3 and the means 20, is preferably short and thermally insulated, in order to reduce losses. On the other hand, the top of these means 20 is connected by a conduit 9 (or 4 ^th conduit) equipped with a valve 6 ₂ (or 4 ^th valve) at the inlet of the autoclave 14. This output is preferably connected to the uppermost or upper part of the tank 20 to evacuate, first, the gaseous part of the fluid if there is any. This duct 9 can be thermally insulated.

 The means 9 and 28 can be connected before entering the reservoir 20 so as to have only one orifice at the top of the latter.

The opening of the valve 6iva make it possible to introduce liquefied gas, cold, into the storage means 20 (the valve 20i being closed) and to put the internal volume of these means at a pressure Pi imposed by the source 2, Pi being for example between 10 bars and 80 bars, for example Pi = 20 bars. The gas liquefaction temperature Ti is imposed by the pressure. Because of the low temperature of the fluid leaving the source 2, its introduction through the conduit 29 will also lead to a vaporization of a portion of the liquefied gas, thereby forming gas which will also be introduced into the means 20. in other words, this preliminary step allows to obtain and to introduce a gas-liquid mixture in the means 20. the opening of the valve 6 ₂ optionally allows the introduction of gas into the enclosure 14.

 The storage means 20 can store, under a pressure which may be several tens of bars, on the one hand gas, and on the other hand the liquid.

 The opening of the valve 2Ο3, preferably after closing the valves

61 and 6 ₂ , for example after the start of a pumping cycle (after starting the pump 10 and pumping liquid from the reservoir 6 by this pump 10), makes it possible to bring the enclosure 20 to the pressure of the reservoir of storage 6. The opening of the valve 20i allows the liquid to flow by simple action of gravity, the tank 20 to the tank 6; at the same time, gas rises from the tank 6 to the tank 20 via the pipe 28. The valves 20i and 2Ο3 can be closed when there is no more liquid in the tank 20.

Initially, when the means 20 are still at atmospheric pressure, they can be filled, by opening the valve 2Ο3, by a gas flow taken from the tank 6. The gas of the storage means 20 can be used, at the beginning of the cleaning cycle, after loading the parts in the autoclave and closing the door 15 (or, more generally, stopping or closing the setting in fluidic communication the enclosure and the external atmosphere), to ensure in the autoclave a pressure, for example about 6 to 15 bar, then allowing the dense fluid to be introduced without forming dry ice. As can be understood from the explanations above and from FIG. 2, this gas is thus not taken from the storage chamber 6, which avoids the problems mentioned in the introduction, in particular the pressure drop, and the cooling consecutive to the chamber 6, and therefore the risk of cavitation of the pump 10. The ratio of the volume of the autoclave to that of the means 20 is preferably chosen to obtain a pressure of a few bars, for example between 5 to 15 bars, in the autoclave; the pressure in the chamber 20 is then substantially that of the reservoir 6. For example the volume of the autoclave 14 is about 85 I, while the volume of the means 20 is about 15 I.

 The formation of a reserve of gas and liquid in the means 20 therefore comprises the introduction, in these means, of gas, on the one hand in the gaseous state, and on the other hand in the liquid state, of preferably at low temperature, or at a lower temperature than that at which the dense or supercritical gas will be subsequently produced.

 Before a cleaning cycle, we can have the following steps:

 a) constitution of a reserve of gas, in the means 20, as explained above,

 b) then loading the parts to be cleaned and closing the door 15 (or, more generally, stopping or closing the fluid communication connection of the chamber and the outside atmosphere),

 c) then introducing gas into the autoclave 14 from the means 20 to form an atmosphere of a few bar,

 d) then the introduction of liquid in the means 20 and gas in the means 14, as explained above, from the means 2.

e) transfer of the liquid from the means 20 to the means 6, without pumping, by the action of gravity. If, before the start of a cleaning cycle, the means 20 are sufficiently supplied with gas, steps b), c) and d) are carried out directly.

 A cleaning cycle can then be performed, by sending dense or supercritical gas, from the means 6, via the valve 63, and using the means 10, 12.

At the end of the cycle, gas contained in the autoclave can be sent to the storage means 6, via the means 17-19, which limits the losses. Then, the chamber 14 is placed at atmospheric pressure, by opening the door 15 and / or the valve 14 ₂ .

 An example of operation of this system is as follows. This example is given for the following values: autoclave 14 with 83 l of internal volume, pumping tank 20 with 17 l and storage pressure of 60 bar in the means 6.

 But the steps below can be implemented with other values, in proportions of those indicated above.

We start from a state where all the valves are closed, the door 15 of the autoclave is open, and the internal reserve 6 is sufficiently full (it may have been filled as explained above). If the pressure in the reservoir 20 is too low, for example less than 5bar (for C0 ₂ because it is substantially the pressure at the triple point) then the valve 2Ο3 can be opened, which increases the pressure in the chamber 20. The valve 2Ο3 can then be closed. If the pressure in the tank 20 is too high, then the valve 20i can be opened. Preferably, the pressure P20 in the enclosure 20 is between atmospheric pressure and the pressure of the enclosure 6. In general, it is sought to maintain in the enclosure 20 a pressure as low as possible to allow filling from source 2.

 1. The door 15 of the autoclave 14 is closed, or, more generally, it stops or closes the fluid communication between the autoclave 14 and the outside atmosphere; inside the autoclave 14 is then at atmospheric pressure. The pumping tank 20 is itself at a pressure P20, for example greater than 5 bar.

2. The valve 62 is open. The CO2 gas present in the pumping tank 20 is distributed between the autoclave 14 and the pumping tank 20; the pressures are balanced between the two volumes. The difference in volume of the two speakers is such that the The resulting pressure is less than the external storage pressure 2. In the example given, the resulting pressure is at most about 10 bar in these 2 volumes.

3. As soon as the pressure in the chamber 20 is lower than the pressure of the storage 2, the valve 6i can be opened. Liquid C0 ₂ enters the pumping tank 20. The gas is expelled from the reservoir 20 for pumping and is sent into the autoclave 14 (because the valve 6 ₂ is open). Part of the C0 ₂ is vaporized in contact with the hot walls and also goes to the autoclave 14 via the conduit 9.

4. When the pumping tank 20 is full, the valves 6 ₁ and 6 ₂ are closed. In the example chosen, 17 l of liquid C0 ₂ as well as of gaseous C0 ₂ were then entered in the tank 20. C0 ₂ gas also entered the autoclave 14, which corresponds to the beginning of the filling of the autoclave.

5. The valve 2Ο3 can then be opened, which makes it possible to transfer C0 ₂ gas from the storage volume 6 to the tank 20 and increases the pressure of the latter to that of the means 6.

 6. When the pressures are equal, the valve 20i is open. The liquid in the pipe 23, denser than the gas of the pipe 28 goes down in the tank 6 and the gas rises in 28. All the liquid of the tank 20 is transferred to the tank 6.

 7. When all the liquid is out of the tank 6, the valves 20i and 2Ο3 can be closed.

8. If at this time, the pressure in the reservoir 20 is higher than that in the autoclave 14, it is possible to optimize the system by opening the valve 6 ₂ send gas into the autoclave and 14 thus lowering the pressure in the tank 20, which will improve the effectiveness of the next filling. The valve 6 ₂ can be closed as soon as the pressures are close.

 9. At this time the autoclave 14 is, in the example chosen, at about 20 bar, gas. The opening of the valves 63 and 14i and the start of the means 8 allow the end of the filling of the autoclave 14 and the continuation of the cleaning cycle as on a conventional machine.

An exemplary embodiment of a passive pumping reservoir 20 is illustrated in FIG. This reservoir comprises an envelope 250, the inner wall of which is preferably provided with a thermal insulator 252. This internal insulation makes it possible not to vaporize too much of the liquid fluid that the reservoir contains.

 The internal volume of this envelope is closed by a cover 254.

This lid is shown on the top of the tank but it could be down or even secured, for example by welding, the rest of the tank 20. A conduit 264 allows the output of the liquid fluid. This duct is thus connected to the bottom of the tank 20. This duct is preferably thermally insulated, using an insulation or insulating means 265, for example an insulating sleeve, preferably at least until the valve 20i. A duct 256 constitutes an inlet of liquid fluid, it is this duct which, in the diagrams of FIGS. 2 and 3), makes it possible to supply liquid C0 ₂ from the store 2. This duct 256 can advantageously be connected to duct 264 ( as close as possible to the valve 20i) for heating and filling the reservoir 20 in liquid. This conduit is preferably thermally insulated along its entire length.

A conduit 258 is made in the upper part of the tank. It is this duct which makes it possible to extract C0 ₂ gas and to bring it, when the tank is inserted into a system such as that of FIG. 2, to the autoclave 14. This duct can dive a little to inside the enclosure (for example on 10% to 25% or even 35% of the height of the interior volume thereof) to prevent full liquid filling of the entire volume for safety reasons. A duct 266 is formed at the top of the tank to introduce the gaseous fluid from the reserve 6 (case of Figure 2). The valve 20i is preferably just above. Finally, this reservoir may comprise means 260 for detecting a level of liquid contained in the reservoir. It is also possible to put the liquid detection on the pipe 258 (or on the pipe 9 of Figure 2), which simplifies the realization of the tank 20.

In general, the internal storage tank is advantageously large enough not to have to fill each cycle (in the example above, each cycle involves a variation of 17 liters; a volume of at least 17 I). The devices and methods which have been described above are particularly suitable for the implementation of a treatment, for example cleaning, with supercritical carbon dioxide. The fluid in the gaseous state is therefore CO ₂ gas, the fluid in the liquid state is therefore liquid CO ₂ .

 Nevertheless, this device can also be adapted for operation with another fluid, for example a dense fluid under pressure, or, for example still, with oxygen or nitrogen; these fluids can be brought to conditions allowing them to be in the supercritical state (for oxygen: beyond -119 ° C and 50 bar, for nitrogen: beyond -147 ° C and 34 bars).

 Alternatively, another fluid can be implemented, for example a fluid among methane, propane, nitrous oxide, a fluorinated gas, ammonia. They can form a gaseous phase and a liquid phase (in particular for the filling of the reservoir 20), but also be brought to conditions allowing them to be in the dense or supercritical state.

 Furthermore, in combination with one of the fluids already mentioned above, an additive such as a solvent may also be introduced into the chamber 14.

 Whatever the embodiment envisaged, in addition to the means above, a device according to the invention may comprise means 5, of the electronic and / or computer type, and / or a programmed or programmable circuit for controlling and regulating the device. operation of each of the components of the machine, including the pumps and valves, according to a programmed sequence of steps.

 These controller means 5 can comprise circuits, which make it possible to send to each of the components of the machine the instructions and / or the voltages making it possible to drive it according to a predefined sequence. In particular, these means will make it possible to implement a cleaning preparation cycle and / or a cleaning cycle as described above, and in particular to regulate the fluid transfer steps:

 between the means 2 and 6,

 between the means 2 and the storage means 20

between the means 6 and 20, between the means 6 and 14.

More specifically, these means will control the duration of the opening or closing of the valves 6ι-6 ₄ , 20ι, 2Ο3, but also any other valves of the system, and the operation, in particular, the pump 10, and means 12.

 This assembly 5 may further optionally receive signals corresponding to measurements made with the aid of one or more pressure sensors, for example arranged to measure the pressure in the autoclave 14, or in the storage means 20, and can process and use them to control one or more of the machine components.

 This controller assembly 5 can communicate with a user interface to inform a user about the state of the machine, in particular its operating cycle.

 An embodiment of these means 5 is described below in more detail with reference to FIG. 4.

 In this example, these means comprise storage means 53 for storing the instructions relating to data processing, for example to perform a method of the type described above.

 According to an exemplary embodiment, the controller 5 comprises a central unit, which itself comprises a microprocessor 56, a set of non-volatile memories and RAM 57, peripheral circuits, all these elements being coupled to a bus 55. Data can stored in the memory areas, including data for implementing a method according to the present invention or for controlling a machine according to the present invention. Means 59 will make it possible to manage the flow of input and output data, from the other components of the machine, and towards the latter.

Alternatively, this controller assembly 5 can be implemented as an FPGA (Field Programmable Gate Array, or programmable logic circuit) or an ASIC (Application Specifies Integrated Circuit or specialized integrated circuit). The means 54, which may comprise display means, may optionally allow a user to interact with the operation of a machine according to the invention, for example by intervening on a particular step of an operating cycle.

 A machine according to the invention, and a method of operation of such a machine, as described above, makes it possible to save components (no filling pump such as pump 3 of FIG. corresponding maintenance), operating time, and material used.

 The invention has been described above in the context of the implementation of a dense fluid under pressure, in particular carbon dioxide in the supercritical state. It can be applied to other fluids, in particular nitrogen or oxygen.

The invention has been described above for cleaning process. But other methods can be implemented using a device or a method according to the invention, the appropriate fluid being used in the dense state, or even super-critical. For each of the different examples given below, C0 ₂ can be used.

 In all cases, the fluid used, dense or super-critical, bathes the treated parts. The contact, more or less long, between the latter and the fluid causes the desired treatment.

 This is the case, for example, of a debinding process or an extraction process (cleaning being a special case of extraction).

 A debinding process makes it possible to extract a binder from a part made of an alloy, for example from a powder such as a powder assembled in a paraffin or in any other suitable binder.

 For example still, a process for extracting one or more natural substances can be implemented, in particular in the pharmaceutical or agri-food industry.

A method of extraction, or degreasing, can be implemented also to treat natural wool, in order to extract the ooze. Usually, this type of treatment is performed by perchlorethylene or water.

 The invention can also be used in processes for impregnating or supplying product carried by the supercritical fluid within the material to be treated.

 The invention also makes it possible to implement a sterilization process (for example in the agri-food or medical field), at low temperature, based on the penetration power of the gas, at high pressure, which will be able to penetrate into the material to be treated. and go neutralize, or kill, infectious agents.

 More generally, any type of part can be treated by a method according to the invention.

 The materials which can be processed by the process of the invention are generally solid materials, for example:

 - metals,

 metallic alloys, possibly plated, such as aluminum, titanium, steel, stainless steel, copper, brass, and any other alloy, or metal plated,

 ceramic materials, polymer materials, powders, especially powders of the materials mentioned above,

 - Textile materials, natural or synthetic, or leather, - grinding sludge, for example from a bar turning process.

 The processed parts can be, for example:

 - parts of the aerospace or automotive industry,

 - timepieces and / or micromechanics,

 - electrical or electronic connectors,

 - semiconductor material components of the microelectronics industry,

 - medical or surgical devices or tools, etc.

 - clothing, or natural materials used in the textile industry, for example wool or leather.

Claims

1. Dense fluid treatment device, for example a fluid in the supercritical state, comprising:  a) a treatment chamber (14) intended to receive parts to be treated, and provided with means (15) to put the enclosure in fluid communication with the external atmosphere, b) means for supplying said chamber dense fluid, for example a fluid in the supercritical state, comprising at least one tank ¹ (6) c) a ^2nd container (20) having a lower portion and an upper portion, and having means for connecting, from the fluid point of view, said lower portion to an upper portion of the ¹ tank (6), which is located to a level below the bottom of the ^2nd container (20), the ^2nd container (20) further having an output, fluidly connected to an inlet of the enclosure (14) for processing, d) means (6i) for supplying the ^2nd reservoir in fluid in the liquid state. 2. Device according to Claim 1, the means (6i) for supplying the ^2nd tank having at least one the ^first conduit (29) and the valve ^era (6i). 3. Device according to one of claims 1 or 2, said lower part of the ^2nd container (20) being connected, by means comprising at least one 2 ^nd conduit (23) and a ^2nd valve (20i) to a portion greater than ¹ tank (6). 4. Device according to claim 2 or 3, further comprising means (265) for thermally insulating the said ^first conduit (29) and / or said ^2nd line (23). 5. Device according to one of claims 1 to 4, further comprising means (28, 2Ο3) for connecting an upper portion of ^2nd tank and said upper tank ¹ (6). 6. Device according to claim 5, the means (28, 2Ο3) for connecting an upper portion of ^2nd tank and said upper tank ¹ (6) having at least one ^3rd conduit (28) and a ^3rd valve (2Ο3). 7. Device according to claim 6, further comprising means for heating or maintaining at a constant temperature said ^3rd line (28). 8. Device according to one of claims 1 to 7, the means (61) for supplying the ^2nd tank further comprising means (2) for storing a liquid fluid. 9. Device according to one of claims 1 to 8, the means for connecting, from the fluid point of view, the ^2nd container (20), to an inlet of the treatment chamber comprising a ^4th conduit (9) and a 4 ^th valve (62). 10. Device according to one of claims 1 to 9, the means (61) for supplying the ^2nd tank being fluidly connected to the means for connecting, from the fluid point of view, the bottom of the ^2nd tank to an upper portion ¹ tank (6). 11. Device according to one of claims 1 to 10, the ^2nd tank comprising means (260) for liquid level detection. 12. Device according to one of claims 1 to 11, the ^2nd tank comprising means (252) of internal thermal insulation. Process for the preparation of a supercritical fluid treatment cycle by means of a device according to one of claims 1 to 12, in which: a) the ^2nd container (20) is fed, from a source of liquid gas supply (2) with a gas mixture, in gaseous form, and gas in liquid form, b) then, at least part of the gas thus stored in the ^2nd container (20), in gaseous form, is sent to the enclosure (14) for processing, c) and at least part of the gas, and stored in the ^2nd container (20), in liquid form, is sent to the ^1st tank (6) or, respectively, to the enclosure (14). 14. The method of claim 13, further comprising a preliminary step prior to step a), or a step subsequent to step c), sending gas, stored in the ^2nd container (20) as gas, to the chamber (14) for processing, thereby reducing the pressure in the ^2nd container (20) to a value lower than the pressure of the source of liquid gas supply (2). 15. Method according to one of claims 13 or 14, wherein, in step c), at least a portion of the gas, stored in the ^2nd tank (20), in liquid form, is sent to the 1 ^first reservoir (6), and further comprising, prior to step c), a step of allowing the pressure of a gas, in the gaseous state contained in the ^2nd container (20) to be greater than or equal pressure of ¹ tank (6). 16. Method according to one of claims 13 to 15, the 1 ^st tank (6) being connected to a gas outlet of the enclosure (14) treatment. 17. Method according to one of claims 13 to 16, step a) being performed without the action of a pump for pumping fluid from the liquid gas supply source (2). 18. A method according to one of claims 13 to 17, the gas which has limente gas, during step a), the ^2nd container (20) being produced by vaporization of liquefied gas. 19. Method according to one of claims 13 to 18, the liquid gas, in step c), flowing to the ^1st tank (6) by the action of gravitation. 20. Method according to one of claims 13 to 19, the pressure in the ^2nd tank (20) being maintained greater than that of the triple point of the gas contained therein. 21. Process for treating a workpiece, by supercritical fluid, comprising:  a process for preparing a treatment cycle according to one of claims 13 to 20,  - Then the completion of a treatment cycle, with, during at least part of the cycle, feeding the chamber, with super critical gas. 22. The method of claim 21, in which, during the treatment, at least a portion of a gas, which leaves the enclosure, is sent to the ^1st tank. 23. Method according to one of claims 19 to 22, said workpiece being at least partly made of a metal material, and / or a metal alloy, and / or ceramic material, and / or a semi-material. -conducteur, and / or a textile material and / or a natural material. 24. Method according to one of claims 19 to 23, the treatment being an extraction treatment, for example cleaning or degreasing, debinding, or sterilization.