WO2012059679A1

WO2012059679A1 - Pumping installation for obtaining a high vacuum and pumping method using such an installation

Info

Publication number: WO2012059679A1
Application number: PCT/FR2011/052547
Authority: WO
Inventors: Laurent Veyre
Original assignee: Centre National De La Recherche Scientifique - Cnrs -; Universite Lyon 1 Claude Bernard
Priority date: 2010-11-05
Filing date: 2011-10-31
Publication date: 2012-05-10
Also published as: FR2967219B1; FR2967219A1

Abstract

Pumping installation for obtaining a high vacuum and pumping method using such an installation. Specifically, the invention relates to a pumping installation comprising: a chamber (5), first and second vacuum pumps (PAV1, PAV2), and a distribution circuit designed to continuously measure a first pressure (P1) at the inlet of the second vacuum pump (PAV2) and a second pressure (P2) in the chamber (5). If one of the pressures chosen from the first pressure (P1) and the second pressure (P2) is higher than a threshold pressure (Ps), a low vacuum is established with the action of the first vacuum pump (PAV1) alone, otherwise, a high vacuum is established with the first and second vacuum pumps (PAV1, PAV2) acting in series.

Description

Pumping installation for obtaining a high vacuum and pumping method implementing such an installation

The invention relates to a pumping installation for obtaining a high vacuum and to a pumping method implementing such an installation.

The invention applies, in particular, to the fields of industry and research in which operations must be performed under a controlled atmosphere, especially in an oxygen-depleted atmosphere.

Such conditions are, for example, required for surface treatment operations of solid supports on which a deposition of material, such as a catalyst in the development of solid catalysts, is provided. To do this, the solid supports are placed in a reactor which is connected to a pumping installation adapted to evacuate the reactor and thus to control the atmosphere in the reactor.

In particular, the reactor is connected to an outlet of an enclosure having an interior space in which the vacuum is produced. Depending on the desired vacuum level, a first vacuum pump adapted to obtain a vacuum up to a first limit pressure, for example of the order of 10 ^{~ 3} mbar, is connected to an input of the enclosure. To obtain a high vacuum, lower than the first limit pressure, a second vacuum pump adapted to obtain a vacuum to a second limit pressure, for example of the order of 10 ^{~ 5} mbar and below, is used. After priming by the first vacuum pump, the second vacuum pump is connected in series with the first vacuum pump at the inlet of the enclosure.

During use, the interior space of the enclosure may be subject to pressure variations, including an increase in pressure during the reactor change. The pumping installation must therefore have a robustness vis-à-vis the pressure variations in the interior space of the enclosure, and especially as these pressure variations are frequent.

For a long time, a mercury diffusion pump with the desired robustness was used as a second vacuum pump. However, the use of a mercury pump is no longer possible due to provisions prohibiting the use of mercury for the risks it presents.

The invention therefore aims to meet the need for a pumping installation for obtaining a high vacuum which has a satisfactory robustness vis-à-vis the pressure variations in the interior space of the enclosure.

For this purpose, the invention proposes a pumping installation for obtaining a high vacuum comprising: an enclosure comprising an interior space and at least one entrance,

a first vacuum pump having an inlet and an outlet, said first vacuum pump being adapted to obtain a vacuum up to a first limit pressure,

a second vacuum pump having an inlet and an outlet, said second vacuum pump being adapted to obtain a vacuum up to a second lower pressure limit than the first limit pressure,

a distribution circuit adapted to continuously measure a first pressure at the inlet of the second vacuum pump and a second pressure in the interior space of the enclosure and for:

if one of the pressures selected from the first pressure and the second pressure is greater than a threshold pressure, performing a primary vacuum by connecting the inlet of the chamber to the outlet of the first vacuum pump and activating the first pump empty, the second vacuum pump being disconnected from the first vacuum pump and the inlet of the chamber, so as to reduce the second pressure to the threshold pressure,

otherwise, if one of the pressures selected from the first pressure and the second pressure is less than or equal to the threshold pressure, making a secondary vacuum by connecting the inlet of the enclosure to the outlet of the second vacuum pump, in connecting the inlet of the second vacuum pump to the outlet of the first vacuum pump and activating the first and second vacuum pumps so as to decrease the second pressure below the threshold pressure.

Thus, the distribution circuit performs automatic and continuous control of the pumping installation between the primary vacuum and the secondary vacuum. The distribution circuit successively passes the pump installation from the primary vacuum to the secondary vacuum. Moreover, in the event of a leak in the pumping installation at the enclosure, for example as a result of a handling error, in particular when connecting a reactor to the enclosure, or following the reactor breakage the second vacuum pump is automatically isolated and the pumping system automatically returns to the primary vacuum. Such automation makes it possible to obtain a pumping installation offering the desired robustness with respect to pressure variations in the interior space of the enclosure.

The distribution circuit, which returns the pumping system to a stable and secure state that constitutes the primary vacuum, provides improved safety.

The distribution circuit also makes it possible to use different vacuum pumps capable of reaching a high vacuum, which vacuum pumps are however generally sensitive to pressure variations. The adaptability of the pumping system is improved. In addition to increasing the choice of first and second vacuum pumps that can be implemented, the adaptability of the installation of pumping is improved because of the possible setting of the priming pressure and the threshold pressure.

In a particularly advantageous embodiment, the distribution circuit can be adapted to:

if the first pressure is greater than a priming pressure, priming the second vacuum pump by connecting the inlet of the second vacuum pump to the outlet of the first vacuum pump and activating the first vacuum pump the first and second vacuum pumps being disconnected from the inlet of the chamber, so as to decrease the first pressure up to the priming pressure,

otherwise, if the first pressure is less than or equal to the priming pressure, if the second pressure is greater than the threshold pressure, performing the primary vacuum,

otherwise, if the second pressure is less than or equal to the threshold pressure, make the secondary vacuum.

The robustness of the pumping installation is thus further improved because of the automatic and continuous control of the pumping installation between the priming of the second vacuum pump, the primary vacuum and the secondary vacuum. The distribution circuit successively passes the pumping installation from the priming of the second vacuum pump to the primary vacuum and the secondary vacuum. In this way, in the event of a leak in the enclosure, the second vacuum pump is automatically isolated and the pumping installation automatically returns to the primary vacuum, if the pressure increase only occurs in the space inside the enclosure, or on priming the second vacuum pump, if the pressure increase extends to the inlet of the second vacuum pump.

The distribution circuit may include:

a first solenoid valve placed between the inlet of the second vacuum pump and the outlet of the first vacuum pump, a second solenoid valve placed between the inlet of the enclosure and the outlet of the first vacuum pump, and a third solenoid valve placed between the inlet of the enclosure and the outlet of the second vacuum pump,

a first pressure sensor arranged to measure the first pressure, and a second pressure sensor arranged to measure the second pressure,

an electronic control unit in which the priming pressure and the threshold pressure are stored, and to which the first and second vacuum pumps, the first, second and third solenoid valves and the first and second pressure sensors are connected, said electronic control unit being adapted for: if one of the pressures selected from the first pressure and the second pressure is greater than the threshold pressure, open the second solenoid valve, close the first and third solenoid valves and activate the first vacuum pump,

otherwise, if one of the pressures selected from the first pressure and the second pressure is less than or equal to the threshold pressure, open the first and third solenoid valves, close the second solenoid valve and activate the first and second vacuum pumps.

The electronic control unit can be adapted to:

if the first pressure is greater than the priming pressure, open the first solenoid valve, close the second and third solenoid valves and activate the first vacuum pump,

otherwise, if the first pressure is less than or equal to the priming pressure, if the second pressure is greater than the threshold pressure, open the second solenoid valve, close the first and third solenoid valves and activate the first vacuum pump,

otherwise, if the second pressure is less than or equal to the threshold pressure, open the first and third solenoid valves, close the second solenoid valve and activate the first and second vacuum pumps.

The enclosure may further comprise at least one outlet for removably connecting a reactor.

In one embodiment, the second vacuum pump may be an oil diffusion pump. Such a vacuum pump makes it possible to achieve better vacuum levels, that is to say at lower pressures, than those obtained with a mercury diffusion pump and also makes it possible to adjust the second pressure limit as a function of the oil used in the oil diffusion pump. In addition, the solid supports may be in the form of compacted powder or not. In the latter case, the solid supports may be powdery. The oil diffusion pump has shown little sensitivity to powdery solid supports thus providing the pumping system with a robustness with respect to the solid powdery supports.

The distribution circuit can then be adapted to, if the oil of the oil diffusion pump has a temperature below a set temperature, control the heating of the oil diffusion pump.

In another embodiment, the second vacuum pump is a turbomolecular pump.

The pumping installation may further comprise a liquid nitrogen trap placed at the inlet of the enclosure, as well as a gas pipe connected to the enclosure. The distribution circuit can then be adapted to, in primary vacuum, if, after a determined duration, the second pressure remains greater than the threshold pressure, remain in primary vacuum. These provisions improve the safety of the pumping installation by maintaining the primary vacuum pump installation in the event of a leak in the pumping installation at the enclosure, for example when the reactor is poorly connected to the enclosure or when the reactor breaks.

When the distribution circuit is adapted to initiate the priming of the second vacuum pump, the distribution circuit may comprise a reversible manual actuator adapted to impose the priming of the second vacuum pump whatever the first and second pressure . Such an actuator makes it possible to momentarily isolate the enclosure of the vacuum pumps, in particular to perform manipulation on the enclosure.

According to a second aspect, the invention proposes a pumping method for obtaining a high vacuum, said pumping method implementing a pumping installation comprising:

an enclosure comprising an interior space and at least one entrance,

- a distribution circuit,

said pumping method providing for continuously measuring a first pressure at the inlet of the second vacuum pump and a second pressure in the interior space of the enclosure and,

if one of the pressures selected from the first pressure and the second pressure is greater than a threshold pressure, making a primary vacuum by connecting the inlet of the chamber to the outlet of the first vacuum pump and activating the first vacuum pump, the second vacuum pump being disconnected from the first vacuum pump and the inlet of the chamber, so as to reduce the second pressure to the threshold pressure,

otherwise, if one of the pressures selected from the first pressure and the second pressure is less than or equal to the threshold pressure, making a secondary vacuum by connecting the inlet of the chamber to the outlet of the second vacuum pump, by connecting the inlet of the second vacuum pump to the outlet of the first vacuum pump and activating the first and second vacuum pumps, so as to decrease the second pressure below the threshold pressure. In a particularly advantageous embodiment, the pumping method can provide:

if the first pressure is greater than a priming pressure, priming the second vacuum pump by connecting the inlet of the second vacuum pump to the outlet of the first vacuum pump and activating the first pump. empty, the first and second vacuum pumps being disconnected from the inlet of the enclosure, so as to reduce the first pressure up to the priming pressure,

otherwise, if the first pressure is less than or equal to the priming pressure, if the second pressure is greater than the threshold pressure, making the primary vacuum,

otherwise, if the second pressure is less than or equal to the threshold pressure, to realize the secondary vacuum.

When the pumping installation further comprises a liquid nitrogen trap placed at the inlet of the enclosure, the pumping method can provide, in primary vacuum, if, after a determined duration, the second pressure remains greater than the threshold pressure, to remain in primary vacuum.

When the distribution circuit is adapted to perform a priming of the second vacuum pump and comprises a reversible manual actuator adapted to impose the priming of the second vacuum pump regardless of the first and second pressure, said method pumping system providing for:

actuating the actuator to force the priming of the second vacuum pump,

- actuate the actuator again to perform priming, primary vacuum or secondary vacuum depending on the first and second pressures.

Other objects and advantages of the invention will appear on reading the following description of particular embodiments of the invention given by way of non-limiting example, the description being made with reference to the appended drawings in which:

FIG. 1 is a schematic representation of a pumping installation according to one embodiment of the invention, the pumping installation comprising an enclosure, a first vacuum pump adapted to obtain a vacuum up to a first limiting pressure. , and a second vacuum pump adapted to obtain a vacuum up to a second lower limit pressure than the first limit pressure,

FIG. 2 is a block diagram illustrating a pumping method implementing the pumping installation of FIG. 1, the pumping method comprising the successive stages of priming the second vacuum pump, of primary vacuum and of vacuum. secondary, FIG. 3 is a schematic representation of the pump installation of FIG. 1 in the priming step of the second vacuum pump,

FIG. 4 is a schematic representation of the pumping plant of FIG. 1 in the primary vacuum stage, in which the vacuum is produced in the enclosure by the first vacuum pump,

FIG. 5 is a schematic representation of the pumping installation of FIG. 1 in the secondary vacuum stage, in which the vacuum is produced in the chamber by the second vacuum pump connected in series with the first vacuum pump; empty,

FIG. 6 is a schematic representation of the pump installation of FIG. 1, illustrating the connection of a reactor to the enclosure,

FIG. 7 is a schematic representation of the pump installation of FIG. 1, illustrating the passage of the secondary vacuum to the primary vacuum when, following the opening of a valve for the connection of the reactor, the pressure in the enclosure increases beyond a threshold pressure,

FIG. 8 is a schematic representation of the pump installation of FIG. 1, illustrating the transition from the primary vacuum to the secondary vacuum when, following the opening of the valve for the connection of the reactor, the pressure in the enclosure decreases below the threshold pressure,

FIG. 9 is a schematic representation of the pump installation of FIG. 1, illustrating the passage of the secondary vacuum to the priming of the second vacuum pump when, following the opening of the valve for the connection of the reactor. the pressure in the enclosure increases beyond the threshold pressure, and the pressure at the inlet of the second vacuum pump increases beyond a priming pressure,

FIG. 10 is a schematic representation of the pump installation of FIG. 1, illustrating the passage of the secondary vacuum to the priming of the second vacuum pump when, following a leak or a breakage of the reactor, the pressure in the enclosure increases beyond the threshold pressure, and the pressure at the inlet of the second vacuum pump increases beyond the priming pressure,

FIG. 11 is a schematic representation of the pump installation of FIG. 1, illustrating the transition from the priming of the second vacuum pump to the primary vacuum when, following the leakage or the breakage of the reactor, the pressure at the inlet of the second vacuum pump decreases below the priming pressure, the pressure in the chamber remaining above the threshold pressure,

FIG. 12 is a schematic representation of a pumping installation according to a second embodiment of the invention, the pumping installation comprising an enclosure, FIG. 13 is a block diagram illustrating a pumping method implementing the pumping installation of FIG. 12, the pumping method comprising the successive steps of primary vacuum and secondary vacuum.

In the figures, the same references designate identical or similar elements.

FIG. 1 represents a first embodiment of a pumping installation 1 for obtaining a high vacuum, and in particular for obtaining a vacuum at a pressure less than or equal to 10 ^{~ 5} mbar.

In the embodiment shown, the pumping installation 1 applies to the surface treatment of solid supports carried out under a controlled atmosphere, in particular under a depleted oxygen atmosphere, for example for the development of solid catalysts. The invention is however not limited to such an application.

To do this, the pumping installation 1 comprises an enclosure 5 in which the vacuum can be made. The enclosure 5 is cylindrical along an axis, of circular section or the like, and defines an interior space 6. The enclosure 5 is provided with one or more inlets 7, for example one placed at one end of the enclosure 5, 6. The chamber 5 also comprises one or more outlets 8, for example two outlets 8 in FIG. 1, each adapted to allow the removable connection of a reactor 15 visible in FIGS. at 1 1. In particular, the outlets 8 extend radially with respect to the axis of the enclosure 5 and comprise connecting members ensuring the reversible closing of the outlets 8 and allowing a hermetic and rapid connection of the reactors 15. For example, the connecting members of each of the outlets 8 comprise a tubing and a first valve 9 mounted on the tubing.

The reactor 15 may be defined as a device adapted to be the seat of chemical reaction, in which a plurality of components are arranged to react with one another. The reactor 15 comprises, for example, a cylindrical tube 16, of glass or plastic, closed at one end and open at an opposite end. The reactor 15 also comprises connecting members arranged on the open end to ensure reversible sealing. The connection members are, moreover, adapted to cooperate with the connection members of the outlets 8 of the enclosure 5. For example, the connecting members of the reactor 15 comprise a tubing adapted to be fitted in or on the tubing of the organs connecting one of the outputs 8, and a second valve 17.

To evacuate the chamber 5, the pumping installation 1 comprises a first vacuum pump PAV1 and a second vacuum pump PAV2. The first vacuum pump has an inlet 1 1 and an outlet 12 and is adapted to obtain a vacuum to a first pressure limit. In the embodiment, the first vacuum pump PAV1 is a rotary pump, such as a vane pump 10, to achieve a first pressure limit of the order of 10 ^{~ 3} mbar. With the vane pump 10, it is thus possible to obtain at the outlet 12 a suction pressure of up to 10 ^{~ 3} mbar.

The second vacuum pump PAV2 has an inlet 21 and an outlet 22 and is adapted to obtain a vacuum up to a second lower pressure limit than the first limit pressure. In the embodiment, the second vacuum pump PAV2 is an oil diffusion pump 20 making it possible to reach a second limit pressure of the order of 10 ^{~ 5} mbar and below. With the oil diffusion pump 20, it is thus possible to obtain at the outlet 22 a suction pressure of up to 10 ^{~ 5} mbar and below. However, to start, the oil diffusion pump 20, like many pumps to obtain a high vacuum, requires priming, that is to say that the inlet pressure 21 of the diffusion pump 20 the oil 20 must, before starting the oil diffusion pump 20, be brought to a priming pressure Pa, for example of the order of 10 ^-2 mbar, or below this priming pressure Pa In addition, the oil diffusion pump 20, just like many pumps making it possible to obtain a high vacuum, can be connected to the enclosure 5 only if a primary vacuum has been produced, that is to say say that the pressure in the interior space 6 of the chamber 5 must, prior to the connection of the oil diffusion pump 20 to the chamber 5, be brought to a threshold pressure Ps, preferably less than or equal to the priming pressure Pa, for example of the order of 10 ^{~ 3} mbar, or below this threshold pressure Ps. it will be apparent from the following description, the priming of the oil diffusion pump 20 and the primary vacuum can be achieved by the vane pump 10 whose pressure limit is less than or equal to the priming pressure Pa and at the threshold pressure Ps.

In other embodiments, it is possible to implement a first vacuum pump PAV1 other than the vane pump 10 and / or a second vacuum pump PAV2 other than the oil diffusion pump 20 in order to adapt the values for the first limit pressure and / or the second limit pressure to the application of the pumping installation 1.

To interconnect the enclosure 5, the vane pump 10 and the oil diffusion pump 20, a distribution circuit comprising three solenoid valves EV1, EV2 and EV3 is provided.

In particular, a first solenoid valve 31 is placed between the inlet 21 of the oil diffusion pump 20 and the outlet 12 of the vane pump 10 for when it is open, allow the passage of gas between the oil diffusion pump 20 and the vane pump 10 and, when closed, prevent the passage of gas between the oil diffusion pump 20 and the vane pump 10 A second solenoid valve 32 is placed between the inlet 7 of the enclosure 5 and the outlet 12 of the vane pump 10 to, when it is open, allow the passage of gas between the enclosure 5 and the vane pump. 10 and, when closed, prevent the passage of gas between the enclosure 5 and the vane pump 10. A third solenoid valve 33 is placed between the inlet 7 of the enclosure 5 and the outlet 22 of the pump. oil diffusion 20 to, when opened, allow the passage of gas between the enclosure 5 and the oil diffusion pump 20 and, when closed, prevent the passage of gas between the enclosure 5 and the oil diffusion pump 20.

In order to secure the operation of the pumping installation 1 and to ensure its robustness with respect to pressure variations, it is intended to slave the first 31, second 32 and third 33 solenoid valves, the vane pump 10 and the oil diffusion pump 20 to vacuum measurements carried out at different locations of the pumping installation 1.

To do this, the distribution circuit comprises a first pressure sensor 41 placed between the first solenoid valve 31 and the inlet 21 of the oil diffusion pump 20 to continuously measure a first pressure P1 at the inlet 21 of the In FIG. 1, the first pressure sensor 41 is placed downstream of the first solenoid valve 31, that is to say between the first solenoid valve 31 and the inlet of the diffusion pump. 20. Alternatively, the first pressure sensor 41 could be placed upstream of the first solenoid valve 31, at the outlet of the paddle pump 10. The distribution circuit also comprises a second pressure sensor 42 placed in the 6 interior of the chamber 5 to continuously measure a second pressure P2. In the embodiment, the first 41 and second 42 pressure sensors are Pirani type vacuum gauges adapted to measure voids up to about 10 ^-4 mbar. Thus, the Pirani type vacuum gauges are adapted to ensure that the priming pressure Pa and the threshold pressure Ps have been reached. Other types of pressure sensor may, however, be used depending on the voids obtained or to know the value of the high vacuum obtained in the interior space 6 of the enclosure 5. For example, in FIG. pressure 43 is placed in the interior space 6 of the enclosure 5 to measure the value of the high vacuum obtained in the interior space 6. In the embodiment, the third pressure sensor 43 is a Penning type vacuum gauge. adapted to measure voids up to 10 ^-9 mbar.

The vane pump 10, the oil diffusion pump 20, the first 31, second 32 and third 33 solenoid valves and the first 41 and second 42 sensors of pressure are connected to an electronic control unit which continuously controls the activation or starting and deactivation or shutdown of the vane pump 10 and the oil diffusion pump 20 and the opening and closing the first 31, second 32 and third 33 solenoid valves according to the pressure measurements made continuously by the first 41 and second 42 pressure sensors.

The electronic control unit comprises a memory in which the priming pressure Pa and the threshold pressure Ps are stored and electronic components to ensure the automatic control of the pumping system. Among the electronic components, a clock may be provided to control the activation and deactivation of the vane pump 10 and the oil diffusion pump 20 as well as the opening and closing of the first 31, second 32 and third 33 solenoid valves according to time delays stored in the memory.

A communication interface 50 connected to the electronic control unit allows a user to perform a control of the operation of the pumping installation. The communication interface 50 comprises, in the embodiment shown:

a selector 51 enabling the user to operate the pumping installation 1 and, if necessary, to choose an operating mode for example between an automated mode and a manual mode,

a reversible manual actuator 52 embodied in the embodiment represented in the form of two pushbuttons, one labeled "Start" and the other identified as "Stop", allowing the user to momentarily isolate, in a reversible manner, the enclosure 5 with respect to the vane pump 10 and the oil diffusion pump 20,

indicators 53, such as indicator lights, indicating a state of the vacuum pumps PAV1, PAV2 and / or solenoid valves EV1, EV2 and EV3 as will be apparent from the following description.

In other embodiments, other selectors, actuators or indicators and more generally other actuating members and information members may be provided. It can also be provided that the communication interface 50 comprises a screen and a data input device, such as a keyboard and / or an electronic connection to an electronic recording medium, which, when connected to a microprocessor the electronic control unit, can program the electronic control unit, which is then as a programmable controller.

To control the atmosphere in the interior space 6 of the enclosure 5, a gas pipe 2 can be connected to the enclosure 5 to introduce any type of gas or suitable gaseous composition, in particular a neutral gas or a gas intended to serve as a reagent. A pressure sensor 3, such as a capacitive manometer, may be placed on the gas line 2 to control the gas introduction pressure into the chamber 5.

In addition, in order to protect the vane pump 10 but especially the oil diffusion pump 20 components, such as liquid or gaseous reactants, located in the chamber 5 and the reactors 15, a collection device under the A liquid nitrogen trap 4 is placed at the inlet 7 of the enclosure 5. In the case of the use of the oil diffusion pump 20, the liquid nitrogen trap 4 also makes it possible to trapping any oil drops of the oil diffusion pump 20. Depending on the applications and the vacuum pumps used, the liquid nitrogen trap 4 could be replaced by any type of capture device appropriate. In addition, according to the uses and precautions implemented in the use of the pumping installation 1, it could be provided that the pumping installation is devoid of any collection device.

In relation with FIGS. 2 to 5, a pumping method for obtaining a high vacuum implementing the pumping installation 1 as described above is now described.

In FIGS. 2 to 5, it is anticipated that the pumping method is implemented automatically by the electronic control unit, the selector 51 being positioned accordingly.

In a step S1, the electronic control unit continuously receives signals representative of the first P1 and second P2 respectively pressures of the first 41 and second 42 pressure sensors.

In a step S2, the electrical control unit checks whether the priming pressure Pa at the inlet of the oil diffusion pump 20 has been reached.

If this is not the case, that is to say if the first pressure P1 measured by the first pressure sensor 41 is greater than the priming pressure Pa, the electronic control unit controls a priming of the second vacuum pump 20 (step S3).

A priming state of the pumping installation during priming of the oil diffusion pump 20 is shown in FIG. 3. In this priming state, only the first solenoid valve 31 is open, the second one and third 33 solenoid valves being closed, so as to connect the inlet 21 of the oil diffusion pump 20 to the outlet 12 of the vane pump 10, the vane pump 10 and the oil diffusion pump 20 being disconnected from the inlet 7 of the enclosure 5. In addition, the vane pump 10 is activated to reduce the first pressure P1 to the priming pressure Pa. LEDs corresponding to the vane pump 10 and the first solenoid valve 31 illuminate on the communication interface.

At the start of the pumping installation 1, once the pressure P1 has reached the priming pressure, it can be provided that the electronic control unit controls a heating of the oil of the oil diffusion pump 20 In the following process, a continuous measurement of the oil temperature of the oil diffusion pump 20 can be carried out by a suitable sensor connected to the electronic control unit in order to be able to control the heating of the pump. with oil diffusion 20, if the oil of the oil diffusion pump 20 has a temperature below a set temperature.

The electronic control unit continuously measuring the first pressure P1, as soon as it becomes less than or equal to the priming pressure Pa, the electronic control unit checks whether the threshold pressure Ps in the interior space of the enclosure 5 has been reached.

If this is not the case, that is to say if the second pressure P2 measured by the second pressure sensor 42 is greater than the threshold pressure Ps, the electronic control unit controls the passage to the primary vacuum ( steps S4 and S5).

A primary vacuum state of the pumping installation 1 is shown in FIG. 4. In this state of primary vacuum, the vacuum is made in the enclosure 5 by the vane pump 10. To do this, the unit of electronic control controls the opening of the second solenoid valve 32 and the closing of the first 31 and third 33 solenoid valves, thereby connecting the inlet 7 of the enclosure 5 to the outlet 12 of the vane pump 10 while disconnecting the diffusion pump 20 of the vane pump 10 and the inlet 7 of the enclosure 5. The electronic control unit also controls the activation of the vane pump 10. In the state of primary vacuum, the second pressure P2 in the interior space 6 of the chamber 5 decreases to the threshold pressure Ps. LEDs corresponding to the vane pump 10 and the second solenoid valve 32 illuminate on the communication interface. The oil diffusion pump 20, initiated but disconnected from the enclosure 5 can be activated, a corresponding indicator light being lit.

In the embodiment shown, at the start of the pumping installation 1, provision can be made to condition the first passage to the primary vacuum to the manual actuation of the push button 52 "Start", which makes it possible to remove the enclosure 5 of its insulation by opening the second solenoid valve 32 and connect the vane pump 10 to the enclosure 5.

In addition, at this stage of realization of the primary vacuum, a delay can be provided. When the primary vacuum state of the pump installation 1 starts, the clock of the electronic control unit starts. If, after a fixed period T, the second pressure P2 remains greater than the threshold pressure Ps, the pump installation 1 remains in the state of primary vacuum described above. The communication interface may, if appropriate, emit an alarm signal in the form of a light signal from a light, a sound signal or other (step S6). The electronic control unit can then also control the stopping of the heating of the oil diffusion pump 20 after the determined duration T.

Provisions concerning the maintenance of the pumping installation 1 in the state of primary vacuum allow, when the pumping installation 1 implements a trap of liquid nitrogen 4 as in the present embodiment, to ensure the evacuation of gases to avoid any risk of sudden relaxation of the gas possibly condensed may cause the explosion of the liquid nitrogen trap. When the pumping installation 1 has another collection device or is not equipped with it, provision can be made to stop the vane pump 10 and the oil diffusion pump 20, after the determined period T has elapsed.

The electronic control unit continuously measuring the second pressure P2, as soon as this becomes lower than or equal to the threshold pressure Ps, the electronic control unit proceeds to the production of a secondary vacuum (steps S4 and S7) .

A secondary vacuum state of the pump installation 1 is shown in FIG. 5. In this state of secondary vacuum, the electronic control unit controls the opening of the first 31 and third 33 solenoid valves, the closing of the second solenoid valve 32 and the activation of the vane pump 10 and the oil diffusion pump 20. The inlet 7 of the chamber 5 is then connected to the outlet 22 of the oil diffusion pump 20 whose input 21 is connected to the output 12 of the vane pump 10. In this way, the vacuum is realized in the chamber 5 by the oil diffusion pump 20 connected in series with the vane pump 10, so that decrease the second pressure P2 below the threshold pressure Ps and up to the second limit pressure. In this state of secondary vacuum, the indicators corresponding to the vane pump 10, the oil diffusion pump 20 and the first 31 and third 33 solenoid valves are lit.

It is also possible, at this stage, to provide a timer indicating to the user that the pumping installation 1 and, in particular, the oil diffusion pump 20 are in a secure state if, after a determined period of time, the first P1 and second P2 pressures remain respectively lower than the priming pressure Pa and the threshold pressure Ps. A corresponding indicator light can be provided.

Thus, depending on the pressure conditions in the interior space 6 of the enclosure 5 and at the inlet 21 of the oil diffusion pump 21, which are measured continuously, the electronic control unit provides control automatic loop closed of the pumping installation 1 to pass successively and continuously from the priming state, to the state of primary vacuum and then to the state of secondary vacuum. When one of the pressure conditions changes, the pumping installation 1 automatically adjusts accordingly to go from the secondary vacuum to the primary vacuum before returning, if necessary, to the secondary vacuum or to go from the secondary vacuum to the priming before returning, if necessary, to the secondary vacuum through the primary vacuum.

The automatic passage of the secondary vacuum to the primary vacuum or to the priming in which the oil diffusion pump 20 is isolated makes it possible to secure the operation of the pumping installation 1 and to ensure its robustness vis-à-vis sudden changes in pressure. In the case of the use of an oil diffusion pump 20, such an insulation also makes it possible to prevent the entry of air into the oil diffusion pump 20 and thus the deterioration of the oil by oxidation.

In the embodiment shown, when the pumping installation 1 is in the secondary vacuum state, provision may be made to allow the user to manipulate or intervene on the isolated enclosure 5 with respect to the pump. pallets 10 and the oil diffusion pump 20, by imposing the transition to priming regardless of the pressure values measured by the first 41 and second 42 pressure sensors. To do this, the user can operate the push button 52 "Stop", which has the effect of closing the third solenoid valve 33 and open the first solenoid valve 31, the second solenoid valve 32 is already closed in secondary vacuum. A static vacuum can thus be achieved in the interior space 6 of the enclosure 5. After manipulation or intervention on the enclosure 5, the user actuates the push button 52 "Start". The electronic control unit then resumes the pumping installation in the state corresponding to the pressure conditions measured by the first 41 and second 42 pressure sensors. In particular, if the enclosure 5 has remained static vacuum, no first valve 9 having been opened, the pump installation 1 can resume in secondary vacuum. On the other hand, if the static vacuum has not been maintained, for example if one of the first valves 9 has been opened, the pump installation 1 can resume priming, in primary vacuum or secondary vacuum, depending on the first pressure P1 with respect to the priming pressure Pa and the second pressure P2 with respect to the threshold pressure Ps.

In FIGS. 6 to 1 1, the automatic control of the pumping installation 1 is illustrated in different situations of implementation of the pumping installation 1.

Figures 6 to 1 1 show the connection of a reactor 15 to the chamber 5 while the pump installation 1 is in the state of secondary vacuum. After fitting the pipes of the connection members of the outlet 8 of the enclosure 5 and the reactor 15 (FIG. 6), the first valve 9 is opened, which causes an increase in pressure. in the interior space 6 of the enclosure 5. If this increase in pressure is such that the second pressure P2 becomes greater than the threshold pressure, the electronic control unit automatically controls the passage of the secondary vacuum to the primary vacuum (FIG. ). When the second pressure P2 becomes lower than or equal to the threshold pressure Ps, the electronic control unit automatically controls the transition from primary vacuum to secondary vacuum (Figure 8). A similar control can occur after the opening of the second valve 17.

It should be noted that the pressure increase in the interior space 6 of the enclosure 5 can be avoided or at least reduced by isolating the enclosure 5 during the connection of the reactor 15, that is to say by actuating prior to opening the first valve 9, the push button 52 "Stop" and actuating, after the opening of the first valve 9, the push button 52 "Start".

FIG. 9 represents a situation in which, when a reactor 15 is connected to the enclosure 5 while the pumping installation 1 is in the secondary vacuum state, the pressure increase propagates in the pump installation 1 so that not only the second pressure P2 becomes greater than the threshold pressure Ps but also the first pressure P1 becomes greater than the priming pressure Pa. The electronic control unit then automatically controls the passage of the vacuum secondary to the priming of the oil diffusion pump 20 and successively to the primary vacuum and the secondary vacuum when the first P1 and second P2 pressures meet the pressure conditions.

Figures 10 and 1 1 show a situation in which the reactor 15 connected to the enclosure 5 breaks while the pump installation 1 is in the state of secondary vacuum. The enclosure 5 and the distribution circuit are vented so that the first P1 and second P2 pressures are respectively greater than the priming pressure Pa and the threshold pressure Ps. The electronic control unit then controls automatically the passage of the secondary vacuum to the priming of the oil diffusion pump 20. Once the first pressure P1 becomes less than or equal to the priming pressure Pa, the pumping installation 1 goes into the state primary vacuum, without going into the secondary vacuum state because the chamber 5 is in the atmosphere and the second pressure P2 remains above the threshold pressure Ps. Given the use of the liquid nitrogen trap 4, it is expected that the pump installation 1 remains in the state of primary vacuum. In a pumping installation without a liquid nitrogen trap, it would be possible to stop the vane pump 10 and the oil diffusion pump 20 after priming the oil diffusion pump 20. As indicated above, other types of second vacuum pump can be implemented in a pumping installation 1 and in a pumping process similar to those described above.

In particular, in a second embodiment, the oil diffusion pump 20 is replaced by a turbomolecular pump as a second vacuum pump.

In such an embodiment, in order to limit the risk of damage to the turbomolecular pump, it is preferable when connecting the reactor 15 to the enclosure 5 or any other manipulation on the enclosure 5, to provide for isolation. enclosure 5 by actuating, prior to manipulation, the push button 52 "Stop" and actuating, after manipulation, the push button 52 "Start".

Figures 12 and 13 show a second embodiment of a pump installation 1 for obtaining a high vacuum.

This embodiment, similar to the first embodiment described above, will not be described in detail and reference will be made to the foregoing for further details.

The second embodiment differs mainly from the first embodiment in that it implements a simplified pumping method that provides control of the pumping installation only between the primary vacuum and the secondary vacuum described above. It should be noted that to enable such control, the first pressure sensor is placed upstream of the first solenoid valve EV1, at the outlet of the first vacuum pump 10.

Figure 12 illustrates the simplified pumping method, preferably implemented automatically by the electronic control unit.

The electronic control unit continuously receives signals representative of the first P1 and second P2 respectively pressures of the first 41 and second 42 pressure sensors.

The electrical control unit checks whether the threshold pressure Ps has been reached at the output of the first vacuum pump 10. Alternatively, the electrical control unit can check if the threshold pressure Ps has been reached in the enclosure 5 .

If this is not the case, that is to say if the first pressure P1 measured by the first pressure sensor 41, or alternatively the second pressure P2 measured by the second pressure sensor 42, is greater than the threshold pressure Ps, the electronic control unit controls the passage to the primary vacuum, the first 31 and third 33 solenoid valves being closed and the second solenoid valve 32 open. In this state of primary vacuum, a delay similar to that described above can also be provided. As soon as the first pressure P1, or alternatively the second pressure P2, becomes less than or equal to the threshold pressure Ps, the electronic control unit proceeds to the production of a secondary vacuum, the first 31 and third 33 solenoid valves being open. and the second solenoid valve 32 closed, for example instantaneously.

Thus, depending on the pressure conditions at the outlet 12 of the first vacuum pump 10 or in the interior space 6 of the enclosure 5, the electronic control unit can provide automatic closed loop control of the installation pumping 1 to pass successively and continuously from the primary vacuum state to the secondary vacuum state. When one of the pressure conditions changes, the pumping installation 1 automatically adjusts accordingly to go from the secondary vacuum to the primary vacuum before returning, if necessary, to the secondary vacuum.

As before, the automatic passage of the secondary vacuum to the primary vacuum in which the oil diffusion pump 20 is isolated makes it possible to secure the operation of the pumping installation 1 and to ensure its robustness with respect to sudden pressure variations.

Claims

1. Pump installation (1) for obtaining a high vacuum comprising:

an enclosure (5) comprising an interior space (6) and at least one inlet (7), - a first vacuum pump (10) having an inlet (1 1) and an outlet (12), said first vacuum pump (10) being adapted to obtain a vacuum up to a first pressure limit,

a second vacuum pump (20) having an inlet (21) and an outlet (22), said second vacuum pump (20) being adapted to obtain a vacuum up to a second lower pressure limit than the first limit pressure,

a distribution circuit adapted to continuously measure a first pressure (P1) at the inlet (21) of the second vacuum pump (20) and a second pressure (P2) in the interior space (6) of the pregnant (5) and for:

if one of the pressures selected from the first pressure (P1) and the second pressure (P2) is greater than a threshold pressure (Ps), realize a primary vacuum by connecting the inlet (7) of the enclosure (5) at the outlet (12) of the first vacuum pump (10) and activating the first vacuum pump (10), the second vacuum pump (20) being disconnected from the first vacuum pump (10) and the inlet (7) of the enclosure (5), so as to reduce the second pressure (P2) to the threshold pressure (PS),

otherwise, if one of the pressures selected from the first pressure (P1) and the second pressure (P2) is less than or equal to the threshold pressure (PS), make a secondary vacuum by connecting the inlet (7) of the enclosure (5) at the outlet (22) of the second vacuum pump (20), by connecting the inlet (21) of the second vacuum pump (20) to the outlet (12) of the first vacuum pump ( 10) and activating the first (10) and second (20) vacuum pumps, so as to decrease the second pressure (P2) below the threshold pressure (Ps).

Pumping plant (1) according to claim 1, wherein the distribution circuit is adapted to:

if the first pressure (P1) is greater than a priming pressure (Pa), priming the second vacuum pump (20) by connecting the inlet (21) of the second vacuum pump (20) to the outlet (12) of the first vacuum pump (10) and activating the first vacuum pump (10), the first (10) and second (20) vacuum pumps being disconnected from the inlet (7) of the enclosure (5), so as to reduce the first pressure (P1) to the priming pressure (Pa),

otherwise, if the first pressure (P1) is less than or equal to the priming pressure (Pa), if the second pressure (P2) is greater than the threshold pressure (Ps), realize the primary vacuum,

otherwise, if the second pressure (P2) is less than or equal to the threshold pressure (PS), make the secondary vacuum.

Pumping plant (1) according to claim 1 or 2, wherein the distribution circuit comprises:

a first solenoid valve (31) placed between the inlet (21) of the second vacuum pump (20) and the outlet (12) of the first vacuum pump (10), a second solenoid valve (32) placed between the inlet (7) of the enclosure (5) and the outlet (12) of the first vacuum pump (10), and a third solenoid valve (33) placed between the inlet (7) of the enclosure (5) and the outlet (22) of the second vacuum pump (20),

a first pressure sensor (41) arranged to measure the first pressure (P1), and a second pressure sensor (42) arranged to measure the second pressure (P2),

an electronic control unit in which the priming pressure (Pa) and the threshold pressure (Ps) are stored, and to which the first (10) and second (20) vacuum pumps, the first (31), second (32) and third (33) solenoid valves and the first (41) and second (42) pressure sensors are connected, said electronic control unit being adapted to:

if one of the pressures selected from the first pressure (P1) and the second pressure (P2) is greater than the threshold pressure (Ps), open the second solenoid valve (32), close the first (31) and third (33) solenoid valves and activate the first vacuum pump (10),

otherwise, if one of the pressures selected from the first pressure (P1) and the second pressure (P2) is less than or equal to the threshold pressure (Ps), open the first (31) and third (33) solenoid valves, close the second solenoid valve (32) and activate the first (10) and second (20) vacuum pumps.

Pumping plant (1) according to claims 2 and 3, wherein the electronic control unit is adapted to:

if the first pressure (P1) is greater than the priming pressure (Pa), opening the first solenoid valve (31), closing the second (32) and third (33) solenoid valves and activating the first vacuum pump (10),

otherwise, if the first pressure (P1) is less than or equal to the priming pressure (Pa),

if the second pressure (P2) is greater than the threshold pressure (Ps), open the second solenoid valve (32), close the first (31) and third (33) solenoid valves and activate the first vacuum pump (10), otherwise, if the second pressure (P2) is less than or equal to the threshold pressure (Ps), open the first (31) and third (33) solenoid valves, close the second solenoid valve (32) and activate the first (10) and second (20) vacuum pumps.

5. Pump installation (1) according to any one of claims 1 to 4, wherein the enclosure (5) further comprises at least one outlet (8) for releasably connecting a reactor (15).

6. Pumping plant (1) according to any one of claims 1 to 5, wherein the second vacuum pump (20) is an oil diffusion pump.

7. Pumping plant (1) according to claim 6, wherein the distribution circuit is adapted to, if the oil of the oil diffusion pump (20) has a temperature below a set temperature, control the heating the oil diffusion pump (20).

8. Pump installation (1) according to any one of claims 1 to 5, wherein the second vacuum pump is a turbomolecular pump.

9. Pump installation (1) according to any one of claims 1 to 8, further comprising a liquid nitrogen trap (4) placed at the inlet of the enclosure (5).

10. Pumping installation (1) according to claim 9, wherein the distribution circuit is adapted to, in primary vacuum, if, after a predetermined duration, the second pressure (P2) remains greater than the threshold pressure, remain in vacuum primary.

1 1. Pumping plant (1) according to any one of claims 2 and 3 to 10 when dependent on claim 2, wherein the distribution circuit comprises a reversible manual actuator (52) adapted to impose the initiation of the second vacuum pump (20) regardless of the first (P1) and the second (P2) pressure.

12. Pumping installation (1) according to any one of claims 1 to 1 1, further comprising a gas pipe (2) connected to the enclosure (5).

13. A pumping method for obtaining a high vacuum, said pumping method implementing a pumping installation (1) comprising:

an enclosure (5) comprising an interior space (6) and at least one entrance (7),

a first vacuum pump (10) having an inlet (1 1) and an outlet (12), said first vacuum pump (10) being adapted to obtain a vacuum up to a first pressure limit,

- a distribution circuit, said pumping method providing for continuously measuring a first pressure (P1) at the inlet (21) of the second vacuum pump (20) and a second pressure (P2) in the interior space (6) of the enclosure (5) and,

if one of the pressures selected from the first pressure (P1) and the second pressure (P2) is greater than a threshold pressure (Ps), to achieve a primary vacuum by connecting the inlet (7) of the enclosure (5). ) at the outlet (12) of the first vacuum pump (10) and activating the first vacuum pump (10), the second vacuum pump (20) being disconnected from the first vacuum pump (10) and the inlet (7) of the enclosure (5), so as to decrease the second pressure (P2) to the threshold pressure (Ps),

otherwise, if one of the pressures selected from the first pressure (P1) and the second pressure (P2) is less than or equal to the threshold pressure (Ps), to make a secondary vacuum by connecting the inlet (7) of the enclosure (5) at the outlet (22) of the second vacuum pump (20), connecting the inlet (21) of the second vacuum pump (20) to the outlet (12) of the first vacuum pump (10) and activating the first (10) and second (20) vacuum pumps, so as to decrease the second pressure (P2) below the threshold pressure (Ps).

Pumping method according to claim 13, providing:

if the second pressure (P2) is greater than the threshold pressure (Ps), to realize the primary vacuum,

otherwise, if the second pressure (P2) is less than or equal to the threshold pressure (Ps), to realize the secondary vacuum.

Pumping method according to claim 13 or 14, wherein the pumping installation (1) further comprises a liquid nitrogen trap (4) placed at the inlet (7) of the enclosure (5), said pumping method providing, in primary vacuum, if, after a determined duration, the second pressure (P2) remains greater than the threshold pressure (Ps), to remain in primary vacuum.

16. A method of pumping according to any one of claims 14 and 15 when dependent on claim 14, wherein the distribution circuit comprises a reversible manual actuator (52) adapted to impose the initiation of the second vacuum pump (20) regardless of the first (P1) and the second (P2) pressure, said pumping method providing for:

actuating the actuator (52) to force the priming of the second vacuum pump (20),

- Operate the actuator (52) again to perform the priming, the primary vacuum or the secondary vacuum according to the first (P1) and second (52) pressures.