Vacuum line and method for controlling a vacuum line

Abstract

The invention relates to a vacuum line (4) and a method for controlling a vacuum line (4), wherein an auxiliary pumping device (13) and a dilution gas injection device (15) are controlled according to a first operating mode in which the pressure in the discharge pipe (7) is kept less than or equal to 20,000 Pa or according to a second operating mode in which the pressure in the discharge pipe (7) is greater than 20,000 Pa, and in the second operating mode, the injection of dilution gas into the pumping gas flow, for example into the discharge pipe (7) and / or the rough pumping device (10) and / or the auxiliary pumping device (13) is controlled by means of the dilution gas injection device (15) downstream of the inlet of the rough pumping device (10).

Description

Technical Field

[0001] The invention relates to a vacuum line and a method for controlling a vacuum line. Background Art

[0002] In the semiconductor, flat panel display, and photovoltaic manufacturing industries, the gases used in the manufacturing processes are typically processed through a gas handling unit after passing through a rough vacuum pump.

[0003] Some of these methods are said to be risky because the gases conveyed in the vacuum lines are flammable and / or explosive. By way of example, hydrogen, silane, TEOS and hydrides may be mentioned.

[0004] In addition to these hazardous gaseous substances, reduced solids—that is, unoxidized substances such as silicon powder or polysilane polymers—may also be deposited in vacuum lines. These deposits can accumulate over time and contribute to other hazardous conditions. Some non-oxidized deposits are highly flammable and can ignite, for example, due to sudden, strong pumping or simply by operators venting the lines or vacuum pump during maintenance.

[0005] Due to the enormous energy released, some explosions can be particularly destructive. This is particularly true of chain explosions. The first explosion is initiated by flammable gases. This explosion disturbs any deposits of reduced solid matter in the pipeline. These flammable solid deposits, stirred by the blast wave, then undergo a "super-explosion."

[0006] Therefore, the risk of personal injury and damage to the equipment is very high.

[0007] The current method used to solve this problem is to continuously dilute the pumped gas with a neutral gas (usually nitrogen). The neutral gas flow rate is determined so that it responds to the most unfavorable pumping situation plus a safety margin.

[0008] However, this solution has a number of disadvantages.

[0009] First, the large-scale nitrogen supply in the vacuum line involves additional costs related to gas consumption, as well as the energy consumption of the vacuum pumps, heating equipment, and gas handling equipment required to handle the large dilution gas flow. Furthermore, the cooling of the vacuum line caused by gas dilution leads to other disadvantages, particularly due to the cost and risk of failure of the heating elements. Such a large supply of neutral gas also requires excessively high power ratings for the gas handling equipment and roughing pumping equipment.

[0010] Dilution of the nitrogen also results in the formation of nitrogen oxides or "NOx", such as NO2, in the gas treatment equipment. Nitrogen oxides are toxic and constitute atmospheric pollutants which, in turn, must be treated.

[0011] Finally, it has been observed that this solution has reached its limits, as the addition of dilution gas is increasingly insufficient for some recent processes, either due to insufficient pumping capacity of the vacuum pump or insufficient processing capacity of the gas handling unit. In these extreme operating conditions, problems may arise related to the reliability of the vacuum pump or the gas handling unit.

[0012] Another solution could be to reduce the temperature of the pipes and vacuum pumps, especially to prevent thermal decomposition of the precursors and minimize chemical reactions. However, it is also important to maintain high temperatures to prevent the risk of deposition due to condensation.

[0013] Another issue is that some manufacturing processes, particularly in the semiconductor industry, tend to use increasingly unstable precursors. Substrate patterns are becoming thinner and substrates are becoming thicker, meaning they have many layers produced in numerous process steps. To reduce the thermal balance, which risks damaging the substrate chips, newer generations of molecules are being used that decompose at lower temperatures. The downside is that they are also more susceptible to deposition in vacuum lines, potentially resulting in significant deposits.

[0014] Furthermore, some of the used condensable gaseous substances can solidify into solid by-products and deposit in particular in the form of a layer on moving or stationary parts of the vacuum pump or the pipeline, which can lead to blockage of the pipeline. Summary of the Invention

[0015] One object of the present invention is to improve the safety of pumping devices and vacuum lines conveying flammable and / or explosive gases. Another object is to reduce the presence of deposits of condensable substances or to delay / minimize the decomposition of precursors that decompose at lower temperatures in exhaust pipes and pumping devices.

[0016] To this end, the present invention relates to a vacuum pipeline comprising:

[0017] - a pumping device comprising at least one rough pumping device configured to discharge the pumped gas at atmospheric pressure,

[0018] - A gas processing device comprising

[0019] o a processing chamber configured to process the gas pumped by the crude pumping device at atmospheric pressure, and

[0020] o Connect the discharge port of the rough pumping device to the discharge pipe of the process chamber inlet,

[0021] Characterized in that the gas processing device comprises:

[0022] - at least one auxiliary pumping device configured to reduce the pressure in the discharge line,

[0023] a dilution gas injection device configured to inject dilution gas into the pumping gas flow downstream of the inlet of the rough pumping device, for example into the exhaust pipe and / or the rough pumping device and / or the auxiliary pumping device, the vacuum line further comprising:

[0024] o a pressure sensor configured to measure the pressure in the exhaust conduit, and

[0025] o a control unit configured to control the auxiliary pumping device and the dilution gas injection device according to a first operating mode in which the pressure in the discharge pipe is maintained at less than or equal to 20,000 Pa (200 mbar) or according to a second operating mode in which the pressure in the discharge pipe is greater than 20,000 Pa (200 mbar), the control unit being configured to control the injection of dilution gas by means of the dilution gas injection device in the second operating mode.

[0026] The dilution gas injection device is, for example, configured to inject the dilution gas into the exhaust pipe and / or the rough pumping device and / or the auxiliary pumping device.

[0027] In the first operating mode, which is the optimal operating mode, the pressure is kept by default below the ignition conditions for the flammable gases transported in the exhaust line. In the second operating mode, flammability risks can be managed through dilution. Therefore, reducing the pressure in the exhaust line limits the injection of dilution gas to the most critical situations. This allows for safe operating conditions while reducing dilution gas consumption. It should also be noted that in the second operating mode, the amount of dilution gas used is lower than that injected according to the prior art.

[0028] While ensuring vacuum line safety, reducing pressure prevents condensable material from depositing in the exhaust piping and crude pumping system, thereby reducing line heating requirements. Reducing line heating prevents thermal decomposition, which reduces precursor conversion and chemical activity kinetics in the crude pumping system, thereby reducing undesirable reactions. Reducing heating also maintains lubricant quality and improves the reliability of the crude pumping system's mechanical components, particularly bearings. This allows for longer intervals between maintenance operations.

[0029] Furthermore, the consumption of dilution gas is limited, which also makes it possible to reduce the energy consumption of the roughing pumping plant and the gas treatment plant and to minimize or even eliminate the formation of nitrogen oxides in the gas treatment plant.

[0030] Reducing the pressure in the vacuum line also reduces the pressure in the rough pumping device, which makes it possible to reduce its size and use less strong and therefore less expensive materials.

[0031] The vacuum line may further comprise one or more of the features described below, alone or in combination.

[0032] The control unit can be configured so as to determine, based on the pressure measured by the pressure sensor and information about the flammable gas to be pumped, the flow rate of dilution gas introduced into the pumped gas flow downstream of the inlet of the rough pumping device, for example into the discharge line and / or the rough pumping device and / or the auxiliary pumping device, in the second operating mode, so that the pressure generated by ignition is kept below 160,000 Pa (1,600 mbar), in particular under the worst conditions of explosion, for example under stoichiometric conditions.

[0033] The dilution gas may include fuel and / or a neutral gas.

[0034] The control unit may be configured to determine the amount and ratio of the fuel and the neutral gas based on information about the combustible gas introduced into the process chamber.

[0035] The control unit may be configured to control the injection of a high flow rate of dilution gas into the pumping gas flow downstream of the inlet of the rough pumping device, for example into the exhaust pipe and / or the rough pumping device and / or the auxiliary pumping device, when the measured pressure exceeds 50,000 Pa (500 mbar).

[0036] The high dilution gas flow rate can be predetermined so that the flammable gas concentration is below 25% of the lower explosion limit (LEL). The most unfavorable pumping situation is thus made safe, with an additional safety margin. This is an emergency operating mode, occasionally used in extreme situations, similar to the established practice in the prior art, which leads to excessive nitrogen consumption. Therefore, maximum dilution is occasional.

[0037] The control unit may be configured to switch off the injection of the purge gas into the rough pumping device in the first operating mode.

[0038] The auxiliary pumping device may include a water jet pump and / or a Venturi gas jet pump and / or a liquid ring pump and / or a dry vacuum pump and / or a vane pump.

[0039] The process chamber may include a burner and / or an electrical system and / or a plasma and / or a scrubber and / or a chemical adsorption cartridge and / or a physical adsorption cartridge.

[0040] The auxiliary pumping device may include a Venturi gas jet pump, the driving gas of which includes fuel and / or oxidant and / or neutral gas.

[0041] The auxiliary pumping device may be configured to determine the amount and ratio of the fuel, the combustion-supporting gas and the neutral gas of the driving gas based on information from the process chamber.

[0042] The venturi gas jet pump may include a heating element configured to heat the drive gas.

[0043] The auxiliary pumping device may be located less than 1 meter, for example less than 50 cm, from the inlet of the gas processing chamber.

[0044] The auxiliary pumping device may include a water jet pump and a hydraulic pump, the hydraulic pump having an inlet arranged in liquid communication with the bath of the scrubber of the gas processing device and an outlet configured to be controllable by a control unit to provide driving liquid for the water jet pump.

[0045] The vacuum line may include a bypass conduit configured to bypass the auxiliary pumping device in the event of an overpressure condition.

[0046] The present invention also relates to a method for controlling a vacuum line as described above, wherein the auxiliary pumping device and the dilution gas injection device are controlled according to a first operating mode in which the pressure in the discharge line is kept less than or equal to 20,000 Pa (200 mbar) or according to a second operating mode in which the pressure in the discharge line is greater than 20,000 Pa (200 mbar), and in the second operating mode, the injection of dilution gas into the pumping gas flow, for example into the discharge line and / or the rough pumping device and / or the auxiliary pumping device, is controlled by means of the dilution gas injection device downstream of the inlet of the rough pumping device. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Further features and advantages of the invention will become apparent from the following description given by way of non-limiting example with reference to the accompanying drawings, in which:

[0048] [ Figure 1 ] Figure 1 A schematic diagram of an example of an installation is shown, wherein only those elements necessary for understanding the invention are shown.

[0049] [ Figure 2A ] Figure 2A A schematic diagram showing a modified example of a vacuum line.

[0050] [ Figure 2B ] Figure 2B A schematic diagram showing another variation of the vacuum line is shown.

[0051] [ Figure 2C ] Figure 2C A schematic diagram showing another variation of the vacuum line is shown.

[0052] [ Figure 2D ] Figure 2D A schematic diagram showing another example of a vacuum line is shown.

[0053] [ Figure 3 ] Figure 3A graph of the explosion pressure P (in millibars) is shown as a function of the hydrogen concentration C (molar fraction in air) for different initial pressure values ​​before the explosion (symbols represent measured values, solid lines represent theoretical values): 100 mbar (10,000 Pa) (hollow triangles), 150 mbar (15,000 Pa) (solid squares), 200 mbar (20,000 Pa) (hollow diamonds), 300 mbar (30,000 Pa) (circles), 500 mbar (50,000 Pa) (solid triangles), 750 mbar (75,000 Pa) (solid squares), 1,000 mbar (100,000 Pa) (solid diamonds).

[0054] In the figures, the same elements have the same reference numerals. DETAILED DESCRIPTION

[0055] The following embodiments are examples. Although the description relates to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment or that these features apply only to a single embodiment. Individual features of different embodiments may also be combined or interchanged to provide other embodiments.

[0056] A roughing vacuum pump is a positive displacement vacuum pump designed to draw in, deliver, and then exhaust the gas being pumped at atmospheric pressure. The rotors in a roughing vacuum pump can be Roots, claw, screw, vane, or scroll types. Roughing vacuum pumps are also designed to start at atmospheric pressure.

[0057] A positive displacement vacuum pump, or Roots blower vacuum pump, is a pump that uses two Roots rotors to draw in, deliver, and then exhaust the gas being pumped. A Roots vacuum pump is installed upstream of and in series with a roughing vacuum pump. The rotors are held by two shafts that are rotated by the Roots vacuum pump's motor.

[0058] The main difference between a Roots vacuum pump and a roughing vacuum pump is that, due to its higher pumping capacity, its pumping stage is larger in size and has larger tolerances. In addition, a Roots vacuum pump cannot exhaust at atmospheric pressure, but must be installed in series upstream of a vacuum pump for use.

[0059] An "upstream" element is an element that precedes another element relative to the flow direction of the pumped gas. In contrast, a "downstream" element is an element that is located after another element relative to the flow direction of the pumped gas. The pumped gas flow represents the gas conveyed in the tubing of the vacuum line by the pumping action.

[0060] The facility 1 comprises an apparatus 2 comprising one or more process chambers 3 connected to one or more vacuum lines 4. The process chambers 3 are adapted to receive one or more substrates, such as semiconductor wafers or flat panel displays or photovoltaic panels.

[0061] The vacuum line 4 comprises one or more pumping devices 5 connected to at least one process chamber 3, and one or more gas treatment devices 6 comprising one or more discharge pipes 7 connecting the discharge outlet 8 of at least one rough pumping device 10 to the inlet 9 of the process chamber 26 of the gas treatment device 6. By way of example, in Figure 1 1 shows a semiconductor device 2, whose process chamber 3 is connected to a vacuum line 4. The exhaust pipe 7 can have different lengths. Between the output of the rough pumping device 10 and the input 9 of the process chamber 26, the exhaust pipe can have a length of between one meter and four meters.

[0062] The pumping device 5 comprises at least one rough pumping device 10 which is configured to discharge the pumped gas at the discharge outlet 8 at atmospheric pressure or at a pressure greater than atmospheric pressure, in particular up to 1,200 mbar (120,000 Pa). The rough pumping device 10 is also capable of discharging the pumped gas at a pressure below atmospheric pressure.

[0063] The pumping device 5 may further include a high vacuum pumping device, which is arranged upstream of the rough pumping device 10 in the flow direction of the pumped gas and in series with the rough pumping device 10, and is disposed between the process chamber 3 and the rough pumping device 10. The high vacuum pumping device may include a Roots compressor 11 and / or a turbomolecular vacuum pump 12.

[0064] The processing chamber 26 is configured to process the gas pumped by the rough pumping device 10 at atmospheric pressure.

[0065] In a manner known per se, the treatment chamber 26 comprises, for example, a burner 23 configured to produce a thermal reaction at high temperature by combustion of hydrocarbons and / or an electrical system configured to produce a thermal reaction at high temperature by means of a heating resistor and / or a plasma and / or a scrubber and / or a chemical adsorption cartridge and / or a physical adsorption cartridge.

[0066] according to Figure 1In the exemplary embodiment shown, the treatment chamber 26 includes a burner 23 and a scrubber 24, which is connected in series with the burner 23 in the direction of gas flow and is arranged downstream thereof. The burner 23 can be a combustion, electric or plasma burner. A reactive gas such as oxygen or air is added to the pumped gas, and the burner 23 causes it to reach a very high temperature, which activates the formation of new chemically reactive soluble substances, which can then be captured by the scrubber 24. A mist can be generated in the burner 23 with the help of water injection nozzles (also commonly known as cooling nozzles) to quickly cool the gas and prevent chemical equilibrium, rather than allowing the dissociated hot gases to recombine with each other or react towards the opposite equilibrium. The scrubber 24 includes, for example, a packed column in which the pumped gas rises countercurrent to the water flow. At the outlet 31 of the gas treatment device 6, the gas can be discharged into the atmosphere or discharged to a central scrubber in the manufacturing plant.

[0067] The gas treatment device 6 further comprises at least one auxiliary pumping device 13 configured to reduce the pressure in the at least one exhaust pipe 7 .

[0068] The auxiliary pumping device 13 can be of any type. The auxiliary pumping device 13 includes, for example, Figure 1 The water jet pump (or water jet pump) and / or Venturi gas jet pump and / or liquid ring pump and / or dry vacuum pump shown, such as Roots, claw and / or screw vacuum pump and / or vane and / or scroll and / or membrane or diaphragm pump.

[0069] If the auxiliary pumping device 13 comprises a venturi gas jet pump, the driving gas injected to induce the pressure drop may comprise a neutral gas, such as nitrogen. The driving gas then contributes to further dilution of the pumped gas from the exhaust pipe 7. The driving gas may also comprise a fuel such as methane and / or an oxidant. The driving gas then contributes to further dilution of the pumped gas from the exhaust pipe 7 without reducing the efficiency of the burner 23 of the gas treatment device 6 and without generating nitrogen oxides.

[0070] The Venturi gas jet pump may include a heating element configured to heat the drive gas. The drive gas may be heated to a temperature, for example, greater than 50°C, such as greater than 500°C. Heating the drive gas can improve the efficiency of the burner 23 of the gas treatment device 6 and prevent powder from depositing at the jet pump outlet. The drive gas may be heated, for example, by means of a heat exchanger in contact with the treatment chamber 26 or with hot components of the pumping device 5, which reduces power consumption.

[0071] The advantage of the gas jet pump is that it does not consume electricity. It is compact and lightweight and can therefore be easily incorporated into the pumping device 5 or the gas processing device 6 ( Figure 2A )middle.

[0072] If the auxiliary pumping device 13 comprises a dry vacuum pump, the purge gas of the dry vacuum pump of the auxiliary pumping device 13 may comprise a neutral gas, such as nitrogen, and / or a fuel such as methane, and / or an oxidant. The purge gas may be further heated, for example, to a temperature above 50° C., for example above 500° C., for example, by means of a heat exchanger in contact with hot parts of the process chamber 26 or the pumping device 5.

[0073] At least one auxiliary pumping device 13 is preferably located at the inlet 9 of the treatment chamber 26, i.e., for example, less than 1 meter, such as less than 50 cm, which usually requires raising the auxiliary pumping device 13, since the inlet 9 of the burner 23 is usually located more than 1.50 m from the ground.

[0074] Generally, the pumping capacity of the auxiliary pumping device 13 is preferably smaller than the pumping capacity of the rough pumping device 10. The pumping capacity of the rough pumping device 10 is, for example, greater than 5m 3 / h and / or for example less than 100m 3 Under these conditions, the auxiliary pumping device 13, which comprises in particular a dry vacuum pump or a liquid ring pump or a vane pump, can be light enough to be positioned as close as possible to the inlet 9 of the process chamber 26 ( Figure 2A ), for example, positioned in the processing chamber 26 ( Figure 2B ), without any risk and without requiring any specific treatment.

[0075] An auxiliary pumping device 13 of the Venturi gas jet pump type is installed, for example, in the end of the burner 23 of the gas treatment device 6 ( Figure 2B ). Fuel, i.e., the combustion-supporting agent of the driving gas, is the gas that supplies the flame of the burner 23.

[0076] The vacuum line 4 may further include a bypass conduit 14 ( Figure 2C ).

[0077] The bypass conduit 14 includes a conduit that bypasses the auxiliary pumping device 13 and a controllable valve or check valve disposed therein and configured to open or close depending on a pressure differential across the check valve / valve. The bypass conduit 14 can bypass the auxiliary pumping device 13 to prevent potential pumping capacity limitations, particularly when pumping strong airflow or in the event of a malfunction of the auxiliary pumping device 13.

[0078] When the dry vacuum pump of the auxiliary pumping device 13 comprises a venturi gas jet pump, the venturi gas jet pump may be incorporated into the check valve of the bypass line 14 ( Figure 2DThe movable gate of the check valve defines a Venturi passage. When the driving gas is ejected at the inlet of the Venturi passage, the check valve can be in a closed position, where the check valve forms a jet pump that assists vacuum pump 13. When the pressure difference across the check valve exceeds a load threshold of the check valve, the check valve can also be in an open position, where the pumped gas bypasses the Venturi passage.

[0079] return Figure 1 , it can be seen that the vacuum line 4 further comprises a dilution gas injection device 15 , a pressure sensor 16 configured to measure the pressure prevailing in the exhaust duct 7 , and a control unit 17 connected to the pressure sensor 16 .

[0080] The dilution gas injection device 15 is configured to inject dilution gas, for example, a neutral gas such as nitrogen and / or fuel, into the pumping gas flow downstream of the inlet of the rough pumping device 10 or, more specifically, downstream of the high vacuum pumping devices 11, 12, where applicable, for example, into the discharge line 7 and / or the rough pumping device 10 and / or the auxiliary pumping device 13. The dilution gas is injected, for example, at the inlet and / or discharge port 8 of the rough pumping device 10 and / or into the last two pumping stages of the multi-stage rough vacuum pump of the rough pumping device 10 and / or upstream of, downstream of, or into the auxiliary pumping device 13.

[0081] The pressure sensor 16 is arranged, for example, at the outlet 8 of the rough pumping device 10 .

[0082] The control unit 17 comprises a controller, a microcontroller, a memory and a computer program which can implement the method for controlling the vacuum line. For example, the control unit is a computer or a programmable logic controller.

[0083] The control unit 17 is configured to control the auxiliary pumping device 13 and the dilution gas injection device 15 according to the pressure measured by the pressure sensor 16 according to the first operating mode or according to the second operating mode.

[0084] In the first operating mode, the pressure in the discharge duct 7 is maintained at less than or equal to 200 mbar (20,000 Pa).

[0085] The auxiliary pumping device 13 capable of reducing the pressure in the discharge pipe 7 can be controlled to pump continuously or intermittently.

[0086] For example, the auxiliary pumping device 13 includes a Venturi gas jet pump, and the control unit 17 is configured to control the driving gas of the jet pump to reduce the pressure.

[0087] According to another example, the auxiliary pumping device 13 includes a water jet pump, and the control unit 17 is configured to control the driving fluid of the water jet pump so that the pressure can be reduced ( Figure 1 ).

[0088] In this case, according to one embodiment, the auxiliary pumping device 13 further includes a hydraulic pump 19, the outlet of which is configured to be controllable by the control unit 17 in order to supply drive liquid to the water jet pump. The inlet of the hydraulic pump 19 is, for example, arranged in liquid communication with a bath 22 of a scrubber 24 of the gas treatment device 6. The gas treatment device 6 may then include a gas / water separator 20 arranged between the water jet pump of the auxiliary pumping device 13 and the inlet 9 of the burner 23 of the gas treatment device 6. Liquid residues can be discharged into the bath 22 via a plunger tube 21.

[0089] In the first operating mode, which is the optimal operating mode, the pressure is therefore kept by default below the ignition conditions of the majority of the flammable gases conveyed in the exhaust duct 7 .

[0090] refer to Figure 3 This can be better understood with the example in Figure 3 It is shown that for hydrogen pressures of 100 mbar (10,000 Pa), 150 mbar (15,000 Pa) and 200 mbar (20,000 Pa), the explosion pressure under stoichiometric conditions - that is, the explosion pressure that would cause the most severe explosion - remains below 1,600 mbar (160,000 Pa). Thus, a set of safety conditions is established in the crude pumping device 10 and the discharge pipe 7 that prevent gas explosions. It is believed that for pressures lower than or equal to 200 mbar (20,000 Pa), the pressure generated by ignition under stoichiometric conditions (also called explosion pressure) is easily suppressed, that is, it does not cause significant damage to the mechanical pumping device 5 or the pipe system. Although Figure 3 This applies to the specific case of hydrogen, but the same behavior is observed for all flammable gases: the stoichiometric explosion pressure – that is, the explosion pressure that could lead to the most severe explosion – remains below 1,600 mbar (160,000 Pa).

[0091] Furthermore, in the first operating mode, there is no need to inject dilution gas to keep it out of flammable and / or explosive conditions, because the vacuum level at a pressure below 200 mbar (20,000 Pa) ensures safety. Therefore, the control unit 17 can control the stopping of dilution gas injection.

[0092] It is also conceivable that the control unit 17 is configured to switch off the injection of purge gas into the rough pumping device 10 in the first operating mode. It is thus easier to maintain a low pressure in the discharge line 7.

[0093] If the pressure cannot be reduced below 200 mbar (20,000 Pa), the control unit 17 is configured to switch to a second operating mode.

[0094] In the second operating mode, the pressure in the discharge duct 7 is higher than 20,000 Pa. The control unit 17 is further configured to control the injection of dilution gas into the pumping gas flow, for example into the discharge duct 7 and / or the rough pumping device 10 and / or the auxiliary pumping device 13, by means of the dilution gas injection device 15. In this second operating mode, which can be regarded as a "degraded" operating mode, the flammability risk can be controlled by dilution.

[0095] The control unit 17 can be configured such that the flow rate of the dilution gas introduced into the pumped gas flow in the second operating mode is determined based on the pressure measured by the pressure sensor 16 and based on information about the flammable gas to be pumped so that, in particular under stoichiometric conditions - i.e. under conditions of flammable gas concentration that reaches an explosion state causing the most destructive effects - the pressure generated by ignition (or explosion pressure) remains below 160,000 Pa (1,600 mbar).

[0096] For example, reference Figure 3 , it can be seen that when the initial pressure before the explosion measured by the pressure sensor 16 is 300 mbar (30,000 Pa) (circles), the [H2] concentration of 32% under stoichiometric conditions must be reduced to the target [H2] concentration of 15%, that is, the concentration to which it is diluted with neutral gas so that the pressure does not exceed the explosion pressure of 1,600 mbar (160,000 Pa).

[0097] According to another example in the figure, when the pressure measured by the pressure sensor 16 is 500 mbar (50,000 Pa) (triangles), the concentration under stoichiometric conditions must be reduced to 6-7% by dilution in order to maintain an explosion pressure below 1,600 mbar (160,000 Pa).

[0098] Although these examples describe concentrations under stoichiometric conditions, in operation, the concentration of the combustible gas before dilution is predetermined by the user based on the maximum flow rate value of the combustible gas introduced into the process chamber 3 .

[0099] When there are multiple flammable gases, the neutral gas dilution rate is determined based on the maximum flow rate of the flammable gases that are simultaneously injected into the process chamber 3 .

[0100] More specifically, first, according to the pressure measured by the pressure sensor 16, the pressure Figure 3 The dilution rate for each combustible gas is determined separately using a data table specific to each gas, as shown in the graph in FIG. The data table can be stored in the control unit 17. The target concentration (to be achieved) for each gas, i.e., the dilution concentration, is then recalculated for all combustible gases introduced simultaneously into the process chamber 3; all gases injected simultaneously contribute to reducing their respective concentrations.

[0101] Therefore, the dilution rate is adjusted according to the amount (flow rate, pressure) of the flammable / explosive gas so that the pressure generated by ignition (or explosion pressure) remains below 160,000 Pa (1,600 mbar).

[0102] The control unit 17 may be further configured to control the injection of a high flow rate of dilution gas into the pumping gas flow downstream of the inlet of the rough pumping device 10, for example, into the discharge pipe 7 and / or the rough pumping device 10 and / or the auxiliary pumping device 13 when the measured pressure exceeds 50,000 Pa (500 mbar). Such a high dilution gas flow rate may be injected preferentially into the rough pumping device 10 and, optionally, simultaneously into the discharge pipe 7.

[0103] The high dilution gas flow rate is predetermined, for example, based on the maximum flow rate of the flammable gas that can be injected into the process chamber 3. This information is predetermined by the user based on the maximum flow rate of the flammable gas introduced into the process chamber. For example, the high dilution gas flow rate is predetermined so that the flammable gas concentration is less than 25% of the lower explosion limit (LEL).

[0104] The most unfavorable pumping scenarios are thus made safe, based on the worst-case conditions for the recipe implemented, for example, in process chamber 3, plus a safety margin provided by 25% of the LEL. This is an emergency operating mode, occasionally used in extreme situations, similar to the permanent practice in the prior art, which resulted in excessive nitrogen consumption. Maximum dilution is therefore only occasional, saving on dilution gas consumption and energy budgets.

[0105] refer to Figure 3 When the hydrogen pressure is greater than 500 mbar (50,000 Pa), the concentration of hydrogen [H2] in the exhaust pipe 7 can be reduced to a value less than 1%, which is 25% of the lower explosion limit (LEL) recommended in the prior art.

[0106] In the first operating mode, the control unit 17 therefore keeps the pressure in the outlet line 7 below 200 mbar (20,000 Pa).

[0107] If the pressure measured in the discharge line 7 remains below 200 mbar (20,000 Pa), the control unit remains in the first operating mode.

[0108] If the pressure cannot be maintained below 200 mbar (20,000 Pa) with the auxiliary pumping device 13 , in particular due to insufficient capacity of the auxiliary pumping device 13 , the control unit switches to the second operating mode.

[0109] In the second operating mode, the control unit 17 controls the injection of dilution gas into the pumping gas flow downstream of the inlet of the rough pumping device 10 , for example into the discharge line 7 and / or the rough pumping device 10 and / or the auxiliary pumping device 13 .

[0110] When the pressure is between 200 mbar (20,000 Pa) and 500 mbar (50,000 Pa), the flow rate of the dilution gas introduced into the pumped gas flow can be determined based on the pressure measured by the pressure sensor 16 and information about the flammable gas introduced into the process chamber 3, so that under the most severe explosion conditions in the event of an explosion, such as stoichiometric conditions, the explosion pressure remains less than 1,600 mbar (160,000 Pa).

[0111] Therefore, when the pressure measured in the exhaust pipe 7 is greater than 200 mbar (20,000 Pa) and less than 500 mbar (50,000 Pa), the pressure in the exhaust pipe 7 is controlled first by the capacity of the auxiliary pumping device 13 and then by the dilution gas set point required to dilute the pumped gas according to the pressure measured in the exhaust pipe 7 and according to information about the flammable gas introduced into the process chamber 3.

[0112] If the pressure measured in the second operating mode returns to below 200 mbar (20,000 Pa), the control unit switches back to the first operating mode.

[0113] If the pressure exceeds 500 mbar (50,000 Pa), the dilution gas can be injected directly into the rough pumping device 10, for example at a predetermined high flow rate value, in order to make the most unfavourable pumping situation safe, plus a safety margin.

[0114] As can be understood from the above, reducing the pressure in the discharge line 7 limits the injection of dilution gas to the most critical situations. In addition to making the vacuum line 4 safer, reducing the pressure also prevents the deposition of condensable materials in the discharge line 7, thereby reducing the heating requirements of the line. Furthermore, reducing the heating of the line avoids thermal decomposition, thereby reducing the conversion of heat-sensitive precursors in the crude pumping device 10. This combination of low pressure and low temperature also reduces the kinetics of chemical activity, thereby reducing undesirable chemical reactions, whether corrosive or likely to clog components of the vacuum line 4. Reduced heating also maintains lubricant quality and improves the reliability of the mechanical parts of the crude pumping device 10, particularly the bearings. Consequently, the intervals between maintenance operations can be significantly increased, improving the economic benefits of the vacuum line 4 and the uptime of production equipment. From an economic perspective, the use of costly and expensive materials can also be reduced. The components of the crude pumping device 10 can be standardized in both design and materials, simplifying the product and making it universally available.

[0115] Furthermore, the consumption of dilution gas is limited, which also makes it possible to reduce the energy consumption of the rough pumping device 10 and, at the same time, of the gas treatment device 6 and to minimize or even eliminate the formation of nitrogen oxides in the gas treatment device.

[0116] according to Figure 1 In the exemplary embodiment shown, the gas treatment device 6 may further comprise at least one bypass device 25 , which is arranged between the discharge pipe 7 and the auxiliary pumping device 13 .

[0117] The bypass device 25 includes an inlet port 25a connected to the exhaust pipe 7, a first outlet port 25b connected to the auxiliary pumping device 13, which is in turn connected to the treatment chamber 26, a second outlet port 25c configured to bypass the treatment chamber 26, and a control member configured to connect the inlet port 25a to the first outlet port 25b or the second outlet port 25c. The bypass device 25 is, for example, a controllable three-way valve.

[0118] The bypass device 25 makes it possible to bypass the auxiliary pumping device 13 and the treatment chamber 26 via the second outlet port 25c only when the pumped gases do not need to be treated. They can thus be directed to the central scrubber of the manufacturing plant.

[0119] The control member may be a manual member. For example, a maintenance operator may operate the control member during maintenance to divert gas from the process chamber 26 during maintenance operations on the process chamber 26. Thus, for example, in the event of a malfunction or maintenance of the burner 23, the pumped gas may be redirected by the bypass device 25.

[0120] The control means can select the first outlet port 25b or the second outlet port 25c, for example, based on information from the process chamber 3, such as the state of the process chamber 3 (processing, shut down, or standby) or information indicating whether the gas must be processed. For example, gas from a shut down or standby process chamber 3 cannot be processed and bypasses the burner 23 via the bypass device 25. Information such as dry contact or pneumatic control can directly control the switching of the control means.

[0121] For example, each process chamber 3 has one bypass device 25, and each apparatus 2 has multiple process chambers 3. Multiple process chambers 3, and therefore multiple bypass devices 25, can further be connected to a single process chamber 26. The second outlet port 25c of the bypass device 25 can further be associated with a common conduit 35.

Claims

1. A vacuum pipeline (4), comprising: - a pumping device (5) comprising at least one rough pumping device (10) configured to discharge the pumped gas at atmospheric pressure, - a gas processing device (6), the gas processing device comprising: a processing chamber (26) configured to process the gas pumped by the rough pumping device (10) at atmospheric pressure, and a discharge conduit (7) connecting the discharge outlet (8) of the rough pumping device (10) to the inlet (9) of the treatment chamber (26), Characterized in that the gas processing device (6) comprises: - at least one auxiliary pumping device (13) configured to reduce the pressure in the discharge duct (7), - a dilution gas injection device (15) configured to inject dilution gas into the pumping gas flow downstream of the inlet of the rough pumping device, The vacuum pipeline (4) further comprises: - a pressure sensor (16) configured to measure the pressure in the discharge duct (7), and - a control unit (17) configured to control the auxiliary pumping device (13) and the dilution gas injection device (15) according to a first operating mode in which the pressure in the discharge pipe (7) is maintained less than or equal to 20,000 Pa or according to a second operating mode in which the pressure in the discharge pipe (7) is greater than 20,000 Pa, the control unit (17) being configured to be able to control the injection of dilution gas by means of the dilution gas injection device (15) in the second operating mode.

2. The vacuum line (4) according to claim 1, characterized in that The control unit (17) is configured to determine the flow rate of the dilution gas introduced into the pumped gas flow downstream of the inlet of the rough pumping device (10) in the second operating mode based on the pressure measured by the pressure sensor (16) and information related to the flammable gas to be pumped, so as to keep the pressure generated by ignition below 160,000 Pa.

3. The vacuum pipeline (4) according to claim 1 or 2, characterized in that The dilution gas includes fuel and / or neutral gas.

4. The vacuum pipeline (4) according to claim 1 or 2, characterized in that The control unit (17) is configured to control the injection of a high flow rate of dilution gas into the pumping gas flow downstream of the inlet of the rough pumping device (10) when the measured pressure exceeds 50,000 Pa.

5. The vacuum pipeline (4) according to claim 1 or 2, characterized in that The high flow rate of the dilution gas is predetermined so that the concentration of the flammable gas is less than 25% of the lower explosion limit.

6. The vacuum line (4) according to claim 1 or 2, characterized in that The control unit (17) is configured to shut off the injection of purge gas into the rough pumping device (10) in the first operating mode.

7. The vacuum line (4) according to claim 1 or 2, characterized in that The auxiliary pumping device (13) comprises a water jet pump and / or a Venturi gas jet pump and / or a liquid ring pump and / or a dry vacuum pump and / or a vane pump.

8. The vacuum line (4) according to claim 1 or 2, characterized in that The treatment chamber (26) includes a burner (23) configured to produce a thermal reaction at high temperature by combustion of hydrocarbons and / or an electrical system configured to produce a thermal reaction at high temperature by means of a heating resistor and / or plasma and / or a scrubber and / or a chemical adsorption cartridge and / or a physical adsorption cartridge.

9. The vacuum line (4) according to claim 1 or 2, characterized in that The auxiliary pumping device (13) comprises a Venturi gas jet pump, the driving gas of which comprises fuel and / or an oxidant and / or a neutral gas.

10. The vacuum line (4) according to claim 9, characterized in that The venturi gas jet pump includes a heating element configured to heat the drive gas.

11. The vacuum line (4) according to claim 1 or 2, characterized in that The auxiliary pumping device (13) is located less than 1 meter from the inlet (9) of the treatment chamber (26).

12. The vacuum line (4) according to claim 1 or 2, characterized in that The auxiliary pumping device (13) comprises a water jet pump and a hydraulic pump (19), wherein the inlet of the hydraulic pump is arranged to be in liquid communication with the bath (22) of the scrubber (24) of the gas treatment device (6), and the outlet of the hydraulic pump is configured to be controllable by the control unit (17) to supply driving liquid to the water jet pump.

13. The vacuum line (4) according to claim 1 or 2, characterized in that The vacuum line comprises a bypass conduit (14) configured to bypass the auxiliary pumping device (13) in the event of overpressure.

14. The vacuum line (4) according to claim 1, characterized in that The dilution gas injection device is configured to inject dilution gas into the discharge pipe (7) and / or the rough pumping device (10) and / or the auxiliary pumping device (13) downstream of the inlet of the rough pumping device.

15. The vacuum line (4) according to claim 2, characterized in that The control unit (17) is configured to determine the flow rate of the dilution gas introduced into the discharge pipe (7) and / or the rough pumping device (10) and / or the auxiliary pumping device (13) downstream of the inlet of the rough pumping device (10) in the second operating mode based on the pressure measured by the pressure sensor (16) and information related to the flammable gas to be pumped, so as to keep the pressure generated by ignition below 160,000 Pa.

16. The vacuum line (4) according to claim 4, characterized in that The control unit (17) is configured to control the injection of high flow rate dilution gas into the discharge pipe (7) and / or the rough pumping device (10) and / or the auxiliary pumping device (13) downstream of the inlet of the rough pumping device (10) when the measured pressure exceeds 50,000 Pa.

17. The vacuum line (4) according to claim 11, characterized in that The auxiliary pumping device (13) is located less than 50 cm from the inlet (9) of the treatment chamber (26).

18. A method for controlling a vacuum line (4) according to any one of the preceding claims, wherein: The auxiliary pumping device (13) and the dilution gas injection device (15) are controlled according to a first operating mode in which the pressure in the discharge pipe (7) is maintained less than or equal to 20,000 Pa (200 mbar) or according to a second operating mode in which the pressure in the discharge pipe (7) is greater than 20,000 Pa, and in the second operating mode, the dilution gas injection device (15) is used to control the injection of dilution gas into the pumping gas flow downstream of the inlet of the rough pumping device (10).

19. The method according to claim 18, wherein: In a second operating mode, the dilution gas injection device (15) controls the injection of dilution gas into the discharge line (7) and / or the rough pumping device (10) and / or the auxiliary pumping device (13) downstream of the inlet of the rough pumping device (10).

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