EP3148716A1

EP3148716A1 - Treatment method and device using a supercritical fluid and injection of additive

Info

Publication number: EP3148716A1
Application number: EP15726118.1A
Authority: EP
Inventors: Alain CHAVRIER; Sébastien FAYETTE
Original assignee: Dfd - Dense Fluid Degreasing
Current assignee: Dfd - Dense Fluid Degreasing
Priority date: 2014-05-28
Filing date: 2015-05-28
Publication date: 2017-04-05
Also published as: CA2949891A1; FR3021554A1; WO2015181313A1; US20170182523A1

Abstract

A treatment device using a supercritical fluid comprises: (a) a chamber (14) for receiving the parts to be treated, provided with an opening and closing door (15), (b) means (6, 8) for supplying a supercritical fluid to said chamber (14), including first fluid storage means (6) and means (10, 12) for bringing the fluid to the supercritical state, (c) second storage means (30) for storing a second fluid, such as an additive, for example a solvent, (d) means (34, 36, 38) for injecting into the chamber the second fluid stored in the second storage means (30), at an atmospheric pressure or at a pressure substantially close to the atmospheric pressure, or together with the supercritical fluid, after the door is closed and the parts to be cleaned are loaded into the chamber.

Description

METHOD AND DEVICE FOR SUPERCRITICAL FLUID TREATMENT WITH INJECTION

ADDITIVE

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.

This 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 can supply, via a pump 3 or a filling compressor and a valve 6i, a storage chamber 6, which stores both gaseous gas and liquefied gas. 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 using a va nne 63, can then be worn, by means 8, under thermodynamic conditions allowing it to be used as a cleaning fluid in the enclosure cleaning 14, also called autoclave and whose input is controlled by a valve 14i. In particular, the means 8 may comprise pumping means 10 and heating means 12. In the case where the fluid is CO ₂ , the pump 10 makes it possible to bring the fluid coming from the reserve 6 to an upper pressure 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, for example 120 bar, and the parts are cleaned by the action of the fluid.

During a cleaning cycle, the fluid is then discharged, expanded by expansion means 16 (mainly comprising a control valve 16 ₂ and a valve 16i), then sent to means 18 forming a separator, which will allow 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.

At the beginning of 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 itself, gas is introduced into the autoclave , at a pressure of the order of a few bars. This gas comes from the speaker 6. To this end, a valve 6 ₂ is disposed on a path defined by a conduit 9 which connects an upper portion of the enclosure 6 and a point disposed between the pump 10 and the heating means 12. This valve and this duct make it possible to take gas, in gaseous form. This gas is then heated by means 12.

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), which is to be avoided because this ice can be very difficult to eliminate quickly.

Furthermore, as described in document WO 02/32593, it is advantageous to use, in combination with the dense fluid used, a liquid additive such as a cosolvent for example. The injection of this additive is generally under pressure, from a storage tank 30 of this additive. This tank can be arranged as shown in FIG. 1, a high-pressure pump 301 being disposed at the outlet of the tank in order to inject it into the corresponding conduit, in which high-pressure fluid circulates.

Such a high pressure pump 301 is expensive. Moreover, such a pump requires maintenance, and is prone to breakdowns. In other words, it also has a cost because of its maintenance.

There is therefore the problem of finding a new method of injecting a solvent into a dense fluid cleaning machine.

More generally, it is sought to be able to inject, economically, an additive, for example a solvent, into a dense fluid treatment machine.

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) an enclosure intended to receive parts to be treated, and provided with an opening and closing door (or, more generally, means for setting in fluidic communication, and then isolating, the inside of the enclosure with respect to to the outside atmosphere),

b) means for supplying said enclosure with dense fluid, for example in a supercritical state, comprising first storage means for said fluid and means for carrying the fluid in the dense state, for example supercritical,

c) second storage means for storing a ^2nd fluid, such as an additive, for example a solvent, also called co-solvent,

d) injection means, for injecting into this chamber, at atmospheric pressure or substantially close to atmospheric pressure, or with the dense fluid, after loading the parts to be treated and then stopping or closing the fluid communication between the interior of the the enclosure and the outside atmosphere, the ^2nd fluid, from the second storage means. Here and throughout, the expression "fluidic communication", applying to 2 volumes, means that a fluid can flow, 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 expression "at atmospheric pressure substantially close to atmospheric pressure" generally means a pressure which may be between 1 and 2 bars or between 1 and 5 bars. Said injection means may comprise a low pressure pump. Or they allow a gravity injection.

In a variant, said injection means may comprise:

means, forming an intermediate reservoir disposed on the path of the fluid leaving said second storage means, between the latter and said enclosure,

means for filling this intermediate reservoir from said second storage means,

and means for injecting into said enclosure, or at the inlet thereof, at least a portion of the contents of said intermediate reservoir means.

According to this embodiment, the device may further comprise:

means for introducing, into said means forming an intermediate reservoir, a fluid under pressure, in the dense state, for example supercritical,

and means for introducing, into said enclosure, or at the inlet thereof, a mixture of this pressurized fluid and the second fluid.

Said intermediate reservoir means may comprise:

- a 1 ^st port to introduce the ^2nd fluid and inject it into the enclosure,

- A ^2nd orifice, different from ^1, for introducing pressurized fluid therein.

Or, said intermediate reservoir means may comprise:

- a 1 ^st port to introduce the ^2nd fluid and the pressurized fluid, - A ^2nd orifice, different from ^1, for injecting said fluid mixture under pressure and the second fluid in the chamber.

The invention therefore also relates to a supercritical fluid treatment device comprising:

a) an enclosure intended to receive parts to be treated, and provided with means for putting in fluid communication the inside of the chamber with an external atmosphere,

b) means for supplying said fluid enclosure, in the supercritical state, comprising first storage means for said fluid and means for bringing this fluid to the supercritical state,

c) second storage means for storing a ^2nd fluid, such as an additive,

d) injection means, for injecting into the chamber, with the supercritical fluid, after loading the parts to be cleaned and closed fluid communication means between the interior of the chamber and the external atmosphere, the ^2nd fluid, from the second storage means, these injection means comprising:

dl) - means, forming an intermediate reservoir, comprising:

- a ^1st orifice in order to introduce, on the one hand, the ^2nd fluid at atmospheric or substantially close to atmospheric pressure and, on the other hand, the pressurized fluid at the surper-critical condition,

- a ^2nd orifice, different from ^1, to inject or introduce a mixture of pressurized fluid and the second fluid in the chamber or at the inlet thereof.

Preferably, said means intermediate container, can store an amount of 2 ^nd independent fluid the quantity of fluid contained in the second storage means.

According to a particular embodiment, said means for introducing, into said enclosure, or at the inlet thereof, a mixture of this pressurized fluid and the second fluid, comprises a valve that opens only if the pressure is greater than a given setting pressure. The invention also relates to a dense fluid treatment method, for example super critical, implementing a device according to the invention, in particular of the type as described above.

The invention also relates to a dense fluid treatment method, possibly super critical, comprising:

a) introducing at least one the ^era workpiece in an enclosure provided with a door opening and closing (or, more generally, means for putting in fluid communication, and then isolate the enclosure with respect to the outside atmosphere), then closing this door (or, more generally, stopping or closing the communication between the enclosure and the outside atmosphere);

b) injecting an additive, for example a solvent into said enclosure, at a pressure substantially equal to or close to atmospheric pressure,

c) then supplying said enclosure with dense fluid and treating said part.

The additive can be injected into the low-pressure chamber, for example using a low-pressure pump or only by gravity.

The additive can be first injected into an intermediate reservoir and then introduced into the enclosure.

The invention also relates to a dense fluid treatment method, for example super critical, comprising, in this order:

a) introducing at least one the ^era workpiece in an enclosure provided with a door opening and closing (or, more generally, means for putting in fluid communication, and then isolate the interior of the enclosure with respect to the external atmosphere), then the closing of this door (or, more generally, the stopping or closing of the fluidic communication between the enclosure and the outside atmosphere),

b) then injecting into said chamber, a mixture of at least one additive and a dense fluid flow, for example super critical, and the treatment of said part by this mixture. According to one embodiment, the additive may be first injected into an intermediate reservoir and then introduced into the enclosure. A dense fluid, under pressure, for example in the supercritical state, can be introduced into the intermediate reservoir, after injection of the additive into the latter, a mixture of this fluid under pressure and the additive being then introduced into the said enclosure, or at the entrance thereof.

The introduction of the mixture into the chamber makes it possible to introduce the additive at the same time as the dense fluid, which makes it possible to dispense with the implementation of a high-pressure pump, and which offers, in in addition, a time saving compared to an introduction of the additive before the implementation of the treatment process.

A pressurized fluid, in the supercritical state, can be introduced into the intermediate reservoir, after injection of additive therein, a mixture of this fluid under pressure and additive being then introduced into said enclosure, or entry of it.

In said intermediate reservoir means, it is possible to introduce:

- the ^2nd fluid by a port ¹ and said mixture is injected in the enclosure, through the same orifice,

- the pressurized fluid by a ^2nd orifice, different from ^1.

Or we can:

introducing, into said means forming an intermediate reservoir, the

^2nd fluid and the fluid under pressure, by the same 1 ^st orifice,

- then injecting said fluid mixture under pressure and the second fluid in the enclosure by a ^2nd orifice, different from ^1.

Said means forming an intermediate reservoir, can store a quantity of ^2nd fluid independent of the amount of fluid contained in the second storage means.

In a process according to the invention, the workpiece may be at least partly made of a metallic material, and / or a metal alloy, and / or ceramic material, and / or a semiconductor material, and / or or in a textile material and / or a natural material, that is to say not initially treated by humans. The treatment may be an extraction treatment, for example cleaning or degreasing, or debinding, or sterilization. The treatment may also be a process for impregnating or supplying product carried by the dense fluid, for example a supercritical fluid, within the material to be treated, for example a dye, or a chemical product.

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 treatment machine, of known type,

FIGS. 2 to 5A show various configurations of another embodiment of a supercritical fluid processing machine, according to the invention,

FIG. 6 is a schematic representation of the control means of a machine according to the invention.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS FIG. 2 shows an exemplary embodiment of a machine according to the invention.

In particular, this machine comprises first storage means 6 (or storage enclosure, called the main storage enclosure of the system), intended to store liquefied gas at several dozen bars, for example 60 bars. 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 fed by a reserve 2, which has for example the shape of a tank (which contains gas at, for example - 20 ° C and 20 bar), to which the device can be connected. This reserve is placed in communication with the storage enclosure 6 via the valve 6i, and a filling pump 3 or a compressor.

The initial filling of this chamber can be carried out as follows. Liquefied gas is introduced by pumping and opening of the inlet valve 6i at the temperature of the reserve 2, for example 20 bar and -20 ° C. During the treatment, this chamber may, in addition, be fed with recycled gas from the treatment chamber 14.

The heating means 7 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 ° C and 30 ° C, and at a pressure between 50 bar and 90 bar.

An autoclave 14, or treatment chamber, accommodates the parts to be treated. This enclosure is provided with a door 15, through which the parts can be introduced into the enclosure, and then, after treatment, extracted from the enclosure. It can also be provided with a vent, or a duct forming a vent, 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, comprising, for example, a pump 10 and heating means 12 make it possible to bring the fluid taken from the chamber 6 under thermodynamic conditions that allow it to be used in the treatment chamber 14. when the fluid is CO 2, the pump 10 can carry the fluid from the reserve 6 to a higher pressure 73.85 bar, and the heating means 12 can raise the temperature of the fluid to a value greater than 31 ° C, these conditions then ensuring the fluid a so-called supercritical 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 16i and a control valve 16 ₂ ) allow the gas to be released at the outlet of the autoclave 14.

Means 18 forming a separator, are used to separate the gas impurities or extracted products that it carries and that result from a previous treatment operation or ongoing.

All of these means make it possible to carry out a treatment cycle, that is to say a set of steps, which mainly comprise:

a) the loading of the parts in the autoclave 14,

b) closing the door 15 and the means 14 ₂ (or, more generally, stopping or closing the setting in fluid communication, that is to say the impossibility of fluid exchange, between the inside of the enclosure and the outside atmosphere),

c) the treatment of the parts by action of the dense fluid on the parts to be treated; this step is carried out at high pressure Po, for example greater than 100 bar, for example still at about 120 bar for C0 ₂ supercritical,

d) reducing the pressure in the enclosure from Po to a value Pi substantially less than Po _; Pi is for example of the order of a few tens of bars, or between 50 bars and 90 bars, or between 60 and 70 bars.

e) the opening of the door (or, more generally, the setting in fluid communication of the interior of the enclosure and the outside atmosphere) and the unloading of the parts; the internal volume of the autoclave is then at atmospheric pressure.

It is sought to introduce an additive to the dense fluid, in order to perform a specific treatment on the parts.

As explained in the application WO 02/32593, for example a cleaning treatment, the addition of a cosolvent to the dense fluid, under pressure, provides an improved extraction of contaminating organic compounds, pollutants, that is, unwanted compounds, from the parts to be cleaned. This cosolvent may be chosen, for example, from water, aqueous solutions, alcohols, for example aliphatic alcohols of 1 to 5 C, such as ethanol, methanol, butanol or ketones, such as acetone, and mixtures thereof.

Among the aqueous solutions, mention may be made of detergent solutions such as anionic and / or cationic surfactants, solutions of complexing agents, chelating agents, buffer solutions, for example of phosphate and / or hydrogen phosphosphate, etc. ; solutions of antioxidants, such as ascorbic acid, to stabilize the material.

Other types of additives may be added in place of or in combination with the solvent:

a perfume additive (added for example at the end of the cycle),

an impregnating product, for example a paint and / or a tanning product (for example chromium VI or a vegetable tannin), and / or an oil, and / or a hydrophobic product.

With respect to the structure which has been described above, the embodiment of FIG. 2 further comprises second storage means 30, or tank, containing or intended to contain an additive to be injected into the front chamber. the beginning, or at the beginning, of a treatment cycle, after loading the parts of the material to be treated in this chamber and closing the door 15 and the means 14 ₂ (or, more generally, the stopping or closing of the fluidic communication of the interior of the chamber and the external atmosphere, that is to say the establishment of a state in which it is impossible to perform any fluid exchange between the interior of the chamber; pregnant and outside atmosphere). This additive is generally stored in the means 30 in liquid form. It is injected at atmospheric pressure, or close to atmospheric pressure (between 1 and 2 bar or between 1 and 5 bar), well below the working pressure. This tank 30 may be provided with means for measuring the pressure and / or the temperature and / or the level and / or the volume of the liquid or the fluid that it contains.

In the structure shown in FIG. 2, the tank 30 is connected, via a valve 32i and a duct 34, to the inlet of the autoclave 14. Optionally, a pump at low pressure 32 may be disposed at the outlet of the tank 30, this pump for injecting the fluid at atmospheric pressure or at a pressure of between 1 and 2 bars. Thus, the additive can be injected into the autoclave 14 at a pressure close to atmospheric pressure. This pump may not be necessary if the tank 30 is above the autoclave 14, the flow being done just by the action of gravity. This injection takes place after closing the door 15 and before injection of the dense treatment fluid.

As already explained above in connection with FIG. 1, it is known to inject an additive into the autoclave 14 with the dense fluid under pressure. For this, it is necessary to implement a high pressure pump 301. For example, in the structure of Figure 1, in the case where solvent is injected upstream of the exchanger 12, mixed with the gas taken from the enclosure 6, it is necessary to increase the pressure of the solvent until it reaches the pressure of the gas sampled.

The injection, according to the invention, of an additive at atmospheric pressure or substantially close to the atmospheric pressure makes it possible to dispense, for the injection of an additive, the use of a high-pressure pump, which is expensive, especially in terms of maintenance.

The operation of this machine is then identical to what has already been described above.

The sequence of steps that takes place at the beginning of a treatment cycle is for example the following:

a - loading the parts and closing the door and the means 14 ₂ (or, more generally, stopping or closing the setting in fluid communication of the interior of the enclosure and the outside atmosphere, c ' that is to say the establishment of a state in which it is impossible to carry out any fluid exchange between the interior of the enclosure and the outside atmosphere),

b - injection of the additive at atmospheric pressure or close to atmospheric pressure,

c - gas injection into the autoclave, to bring it to a pressure of about 5 to 15 bar, to avoid the formation of dry ice. A variant, with a view to an injection of additive at a pressure identical to or substantially close to atmospheric pressure, is illustrated in FIG. 3. In this figure, references identical to those of FIGS. identical or similar. This device further comprises a cartridge 36 in which an amount of additive to be injected into the autoclave can be stored temporarily, at atmospheric pressure, or close to atmospheric pressure, in liquid form, after being taken from the reservoir 30.

Preferably, in order not to use a pump, the cartridge 36 is located below the tank 30 and above the autoclave 14.

In this device, the outlet of the additive tank 30 can be controlled by a set of valves 32 ₁ , 32 ₂ , which will allow:

- In a first step, by opening the valve 32 ₂ , after closing the valve 32i, temporarily store the additive in the cartridge 36, of known volume. The liquid goes from the tank 30 to the cartridge 36 by simple action of gravity. The cartridge 36 is extended by a duct 36i rising higher than the tank 30 and of small section thus allowing to have in the volume of the cartridge 36 an amount approximately independent of the filling of the reserve 30; the valve 32 ₂ can then be closed,

- Then, by opening the valve 32i, the additive, stored in the cartridge 36, can be injected through the conduit 34 to the inlet of the autoclave 14.

This injection of additive is thus only by the action of gravity, without use of pump or energy other than the actuation of the valves.

The sequence of steps at the beginning of the treatment cycle may be identical to the sequence of steps a-c which has been described above.

Yet another variant, with a view to injecting an additive at the inlet of autoclave 14, is illustrated in FIG. 4. In this figure, references identical to those in FIGS. 1-3 designate identical elements or Similar. Again, the cartridge 36 will temporarily store a quantity of additive to be injected into the autoclave, after sampling in the reservoir 30. This time, the volume of the cartridge 36 can be put in communication with the output of the means 8 , to to send, in the cartridge 36, a quantity of dense fluid, possibly supercritical, which will allow to sweep the cartridge and introduce the additive at the inlet of the autoclave 14.

More specifically, in this device, the outlet of the additive reservoir 30 is controlled by the valve 32 ₂ .

In a first step, by opening the same valve 32 ₂ , the additive can be temporarily stored in the cartridge 36, of known volume. The storage pressure in the cartridge is atmospheric pressure or is close to atmospheric pressure. According to a variant illustrated in Figure 4A is used a pump 32 (for example a low-pressure metering pump) located between the reserve 30 and the valve 32 ₂ to fill the cartridge 36 with the desired amount of additive. This quantity then becomes adjustable. This low pressure pump 32, disposed at the outlet of the tank 30, makes it possible to inject the additive into the cartridge 36 at atmospheric pressure or at a pressure of between 1 and 2 bars. This pump 32 may in particular be used when it is not possible to use the action of gravity (in the case of a too viscous additive, for example).

Optionally, means 38i, forming a valve, may be provided downstream of the cartridge 36, on the channel 34. These means 38i can then open only under a given pressure (to which the valve is tared), greater than the pressure at which the additive is stored in the cartridge 36, then ensure the closure of the channel 34 for the additive. A conduit 38 makes it possible to take dense fluid at the outlet of the means 8. If the dense fluid is carbon dioxide, it is then in the super-critical state. A valve 38 ₂ is disposed on this duct 38, and will make it possible to control the introduction of this fluid into the cartridge 36. When this valve is open, the fluid, arriving under high pressure, scans the cartridge 36, taking with it the additive, at a pressure sufficient to open the valve 38i (when it is present). The latter could be replaced by a valve synchronized with the opening of the valve 38 ₂

In the embodiment that has just been explained, the additive enters the cartridge 36, from the tank 30, and leaves, to be injected into the autoclave 14, through the same orifice, which can be located at an ^early end of the cartridge 36. This one is different from that which may be located at a ^2nd end of the cartridge 36 opposite the end the ^age, by which the dense fluid enters the cartridge 36. It is for example arranged opposite to the one through which the dense fluid enters the cartridge.

The sequence of steps that takes place at the beginning of a cleaning cycle is for example the following:

a '- loading parts and closing the door and means 14 ₂ (or, more generally, stopping or closing the setting in fluid communication between the interior of the enclosure and the outside atmosphere, c' that is to say the establishment of a state in which it is impossible to carry out any fluid exchange between the inside of the enclosure and the outside atmosphere),

b '- then gas injection into the autoclave, to bring it to a pressure of about 5 to 15 bar, to prevent the formation of dry ice.

During the treatment cycle, at the desired moment, the opening of the valve 38 ₂ and the closing of the valve 14i allow the dense fluid to pass through the cartridge 36 and to drive the additive.

Yet another variant, with a view to injecting an additive at the inlet of the autoclave 14, is illustrated in FIG. 5. In this figure, references identical to those of FIG. 4 denote identical or similar elements. .

Here again, the volume of the cartridge 36 can be put in communication with the outlet of the means 8, in order to send, in the cartridge 36, a quantity of dense fluid, possibly supercritical, which will make it possible to scan the cartridge and introduce the additive at the inlet of the autoclave 14.

More specifically, in this device, the outlet of the additive reservoir 30 can be controlled by the valve 32 ₂ .

In a first step, by opening the same valve 32 ₂ , the additive can be temporarily stored in the cartridge 36, of known volume.

The duct 38 makes it possible to take dense fluid at the outlet of the means 8. But here, the dense fluid enters the cartridge 36 from below and leaves the top by bubbling through the additive, which allows the entrainment of the fluid. additive gradually by dissolution; the dense fluid will dissolve the additive in its path and take part of it. There is thus an action of the additive extended in time and does not saturate the dense fluid additive at one time.

Depending on the density of the additive with respect to the dense fluid, it will be possible to use a mounting according to FIG. 4 or according to FIG.

The sequence of steps at the beginning of the cleaning cycle may be identical to the sequence of steps a'-b 'which has been described above.

In the two embodiments of FIGS. 4 and 5, the additive is injected with the dense fluid, under pressure, it can therefore be injected when desired during the cleaning cycle, which constitutes an advantageous advantage, in time and flexibility of operation, with respect to the embodiments which have been explained above. According to a variant illustrated in FIG. 5A, a pump 32, for example a low-pressure metering pump, situated between the reservoir 30 and the valve 32 _{2 is used} to fill the cartridge 36 only with the quantity of additive desired. This quantity then becomes adjustable. This low pressure pump 32, disposed at the outlet of the tank 30, makes it possible to inject the additive into the cartridge 36 at atmospheric pressure or at a pressure of between 1 and 2 bars.

In the embodiments of Figures 3-5A, the cartridge 36 may be provided with means for heating or thermostating (or maintaining it at a constant temperature), so that, or so, the dense fluid does not liquefy. This cartridge is thus provided with means which make it possible to maintain the dense fluid that it contains at a temperature such that it is not in liquid form or that it does not condense.

In the embodiments of Figures 3-5A, the cartridge 36 may be equipped with level measuring means so as to adjust the amount of additive. Valve 32 ₂ closes when the desired quantity is reached. This can also be done by measuring the outflow from the tank 30 or by measuring the level variation in the tank 30.

Whatever the embodiment envisaged, in addition to the means above, a device according to the invention may comprise means 5, of electronic and / or computer type, for controlling and regulating the operation of each of the machine components, including 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 gas transfer steps between the means 2 and 6 of a on the other hand, and the storage means 20 on the other hand. More specifically, these means will control the duration of the opening or closing of the valves 32i, 32 ₂ , 38i, 38 ₂ , 383, but also other valves of the system, and the operation, in particular, of 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.

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 input and output data from and to the other components of the machine.

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 operating such a machine, as described above, makes it possible to economize a high-pressure pump such as one of the pumps 301 of FIG.

This saving can be obtained:

or by injection of the low-pressure additive, as for example explained above with reference to FIGS. 2 and 3,

or by injecting the additive at high pressure with the aid of the dense fluid, during treatment, as for example explained above with reference to FIGS. 4 and 5.

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, under conditions allowing them to be in a super-critical state (for oxygen: beyond -119 ° C and 50 bar, for nitrogen: above -147 ° C and 34 bar)

Alternatively, another fluid may be used, for example a fluid selected from methane, ethanol, propane, nitrous oxide, a fluorinated gas, ammonia, alcohol, ethanol, isopropanol, water.

The invention has been described above for a cleaning method.

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, and / or to extract any binder suitable for the manufacture of the alloy.

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 also be used to treat natural wool, in order to extract the ooze.

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.

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

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

The materials, which can be processed by a process according to 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. A supercritical fluid treatment device, comprising: a) an enclosure (14) intended to receive parts to be treated, and provided with means (15, 14 ₂ ) for putting in fluid communication the inside of the chamber with an outside atmosphere,

b) means (6, 8) for supplying said chamber (14) with fluid, in a supercritical state, comprising first means (6) for storing said fluid and means (10, 12) for carrying this fluid in the supercritical state,

c) second means (30) for storing, for storing a ^2nd fluid, such as an additive,

d) injection means (34, 36, 38), for injecting into this chamber, at atmospheric pressure or substantially close to atmospheric pressure, after loading the parts to be cleaned and closed communication means (15, 14 ₂ ). fluid between the interior of the enclosure and the outside atmosphere, the ^2nd fluid, from the second means (30) for storing.

2. Device according to claim 1, said means (34, 36, 38) of injection comprising a low pressure pump (32) or allowing a gravity injection.

3. Device according to claim 1 or 2, further comprising:

means (36) forming an intermediate reservoir disposed in the path of the fluid leaving said second storage means (30) between the latter and said enclosure (14),

- means (32i, 38i 32 ₂₎ for filling the intermediate container from said second means (30) for storing,

and means (32i, 38i) for injecting or introducing, into said enclosure (14), or the inlet thereof, at least a portion of the contents of said means (36) forming an intermediate reservoir.

4. Supercritical fluid treatment device, comprising: a) an enclosure (14) intended to receive parts to be treated, and provided with means (15, 14 ₂ ) for putting in fluid communication the inside of the chamber with an outside atmosphere,

d) injection means (34, 36, 38), for injecting into the chamber, with the super-critical fluid, after loading the parts to be cleaned and closing fluid communication means (15, 14 ₂ ) between within the enclosure and the outside atmosphere, the ^2nd fluid, from the second means (30) for storing, said means (34, 36, 38) for injection comprising:

dl) - means (36), forming an intermediate reservoir disposed, in the path of the fluid exiting said second storage means (30), between the latter and said enclosure (14), these means (36) forming an intermediate reservoir comprising :

- a ^1st orifice in order to introduce, on the one hand, the ^2nd fluid at atmospheric or substantially close to atmospheric pressure and, on the other hand, the pressurized fluid at the surpercritique state,

5. Device according to one of Claims 3 or 4, said means (36) intermediate reservoir-forming, capable of storing an amount of 2 ^nd independent fluid the quantity of fluid contained in the second means (30) for storing.

6. Device according to one of claims 3 to 5, said means (36) forming an intermediate reservoir, being provided with means for maintaining a fluid in gaseous form.

7. Device according to one of claims 3 to 6, said means (38i) for introducing, into said enclosure (14), or at the inlet thereof, a mixture of this fluid under pressure and the second fluid, having a valve opening only if the pressure is greater than a given setting pressure.

8. Supercritical fluid cleaning process comprising, in this order:

a) introducing at least one piece the ^era to be cleaned in a chamber (14) provided with means (15, 14 ₂₎ to allow fluid communication of the interior of the chamber with an atmosphere outside, then stopping or closing this fluid communication between the interior of the enclosure and the outside atmosphere,

b) then injecting into said chamber (14), at atmospheric pressure or substantially close to atmospheric pressure, at least one co-solvent,

c) then supplying said enclosure (14) with supercritical fluid and cleaning said part.

9. The method of claim 8, the co-solvent being injected into the chamber (14) using a low pressure pump (32) or only by gravity.

10. The method of claim 8 or 9, the additive being first injected into an intermediate reservoir (36) and then introduced into the enclosure (14).

11. Supercritical fluid treatment method comprising, in this order:

a) introducing at least one piece the ^era to be cleaned in a chamber (14) provided with means (15, 14 ₂₎ for putting in fluid communication the interior of the enclosure with an outer atmosphere, then stopping or closing the communication between the inside of the enclosure and the outside atmosphere,

b) then:

- introducing into means (36) forming intermediate reservoir, by one orifice ^1, of an additive or a ^2nd fluid, at atmospheric or substantially close to atmospheric pressure, then the fluid pressure, in the supercritical state,

-l'injection a mixture of pressurized fluid, the supercritical state, and the second fluid or the additive, in the enclosure, or at the inlet thereof, by a 2 ^nd port, different from ^1.

12. Method according to one of claims 11, said means (36) forming an intermediate reservoir, storing a quantity of second fluid independent of the amount of fluid contained in the second means (30) of storage.

13. Method according to one of claims 11 or 12, said means (36) forming an intermediate reservoir, being maintained at a temperature to maintain the ^2nd fluid in gaseous form.

14. Method according to one of claims 8 to 13, the additive may be:

a solvent, for example chosen from water, aqueous solutions, alcohols, for example aliphatic alcohols of 1 to 5 C, such as ethanol, methanol, butanol or ketones, such as acetone, and mixtures thereof,

- and / or a perfume, and / or an impregnating product, for example a paint and / or a tanning product, and / or an oil, and / or a hydrophobic product.

15. Method according to one of claims 8 to 14, the dense fluid being nitrogen or oxygen, or a fluid selected from methane, ethanol, propane, nitrous oxide, a gas fluorinated, ammonia, alcohol, ethanol, isopropanol, water.

16. Method according to one of claims 8 to 15, said workpiece being at least partly made of a metallic material, and / or of a metal alloy, and / or of ceramic material, and / or of a semi-metallic material. conductor, and / or a textile material and / or a natural material.

17. Method according to one of claims 8 to 16, the treatment being an extraction treatment, for example cleaning or degreasing, debinding or sterilization, or impregnation.