DEVICE AND METHOD FOR MONITORING INERTING

Description

[0001] The present invention relates to a device and a method for monitoring inerting.

[0002] Inerting generally refers to a process in which the formation of an explosive mixture within a volume is prevented by adding an inert gas, i.e., a gas that is not highly reactive. The inerting of spaces for fire and explosion protection is a well-established practice and is used, among other things, in chemical storage facilities, production plants, and aircraft construction.

[0003] DE 10 2008 013 150 A1, for example, describes a system for inerting a gas volume in an aircraft, in which two exhaust gases are mixed to form an inert gas and then added to the gas volume to be inerted. The inert gas displaces or dilutes reactive gases in the gas volume, thus eliminating any hazard. The system verifies whether sufficient inerting has occurred using a measuring probe located in the gas volume to be inerted, which determines the chemical and material composition of the gas volume after the introduction of the inert gas. If the determined gases in the inerted gas volume correspond to a defined ratio, sufficient inerting is assumed.

[0004] The semiconductor industry uses specialized manufacturing equipment, also known as tools, to produce semiconductor components. These systems have a sealed chamber within which the semiconductor component is built. Process gases are introduced into the chamber for various steps of the manufacturing process. These gases either directly contribute to the assembly of the semiconductor component or provide the necessary manufacturing environment. After a manufacturing step is completed or the semiconductor component is finished, the process gases are removed from the chamber and vented into an exhaust system.

[0005] The process gases can contain toxic or highly reactive gases that must be adequately neutralized in the exhaust system. For example, hydrogen can be used as a process gas, which mixes with atmospheric oxygen and, upon ignition, triggers an explosive reaction. Depending on the formulations and integrated safety features of a tool, up to 100% of the introduced hydrogen can be removed at the tool's outlet. Since not all semiconductor fabs have an explosion-proof exhaust system, or the tools themselves are designed for the removal of residual hydrogen, measures must be taken to protect people and machinery and eliminate the risk of explosion posed by reactive gases.

[0006] One way to achieve this is to perform inerting within the exhaust system. This involves a purging process in which the extracted hydrogen is diluted with sufficient inert gas (e.g., nitrogen) or any oxygen present is displaced, ensuring that the hydrogen-oxygen concentration does not exceed the 2:1 volume ratio (H₂:O₂) required for oxyhydrogen gas reaction, thus eliminating the risk of an oxyhydrogen reaction. In non-intelligent systems, the maximum possible amount of introduced hydrogen is determined, and a corresponding amount of inert gas is added to the exhaust system based on this calculation. This ensures sufficient inerting even if up to 100% of the introduced hydrogen is discharged into the exhaust system. It is understood that this static method consumes an unnecessarily large amount of inert gas.Intelligent systems dynamically adjust the required amount of inert gas to the actual amount of hydrogen being introduced or removed. This ensures that only the necessary amount of inert gas is introduced into the exhaust system, making inerting more efficient. However, for the safe operation of dynamic inerting, continuous monitoring is essential, and in the event of a malfunction, a corresponding response is triggered to bring the system or exhaust system to a safe state.

[0007] However, such monitoring requires that the various gases, or at least the gas fractions, to be diluted or displaced by inerting can be adequately determined. In practice, however, it has been shown that a probe in the volume to be inerted, such as the one shown in the aforementioned DE 10 2008 013 150 A1, cannot simply be used in the exhaust system of a manufacturing plant. Simple probes for determining specific gas fractions do not have the necessary accuracy or speed of detection, or they are generally too prone to malfunctions to reliably determine sufficient inerting. Specialized probes, on the other hand, which offer higher accuracy or are otherwise adapted to the specific conditions in an exhaust system, are usually too expensive for an economical solution.

[0008] US 2018 / 239374 A1 describes various methods for the precise mixing of gases, controlling both the composition and pressure of the gas flows. These methods involve the use of flow meters that monitor the flow rates of multiple gases and transmit this data to a control system. This system regulates the gases to achieve and maintain a predetermined composition. This applies to applications with two or more gases, and the system ensures that the line pressure remains at a specified level. Additionally, composition trimming allows for fine-tuning of the gas mixture without altering the original composition. Gas composition control is achieved through a mixture composition controller that continuously adjusts the flow rates of individual gases based on real-time data.The concept describes both instantaneous and cumulative calculations of the theoretical composition of gas flows and enables alarm functions if the measured values ​​fall outside the specified range. The systems are used in food processing, welding processes, the production of shielding gases, and other industrial processes that require precise gas composition. However, the monitoring of inerting is not disclosed.

[0009] It is therefore an object of the present invention to provide a device and a method which enables better monitoring of inerting in a safer, more flexible and more cost-effective manner.

[0010] According to one aspect of the present invention, this problem is solved by a device for monitoring inerting in an exhaust gas discharge of a manufacturing plant, according to claim 1, comprising: a first flow meter; a second flow meter; and a monitoring unit, wherein the first flow meter is connectable to a first flow meter arranged in a first supply line of a first gas to the manufacturing plant, wherein the second flow meter is connectable to a second flow meter arranged in a second supply line of a second gas to the exhaust gas discharge, wherein the first flow meter is configured to determine a first quantity of gas supplied to the manufacturing plant based on a measured value provided by the first flow meter, and wherein the second flow meter is configured toto determine a second quantity of the second gas, which is supplied to the exhaust gas discharge, based on a measured value provided by the second flow meter, wherein the monitoring unit is configured to trigger a safety-related control function if, depending on the determined first gas quantity and the determined second gas quantity, insufficient inerting is to be assumed.

[0011] According to a further aspect of the present invention, this problem is further solved by a method for monitoring inerting in an exhaust gas discharge of a manufacturing plant, according to claim 12, which comprises the following steps: Providing a first flow meter, a second flow meter, and a monitoring unit; connecting the first flow meter to a first flow meter located in a first supply line for a first gas to the production plant; connecting the second flow meter to a second flow meter located in a second supply line for a second gas to the exhaust system; determining a first quantity of the first gas supplied to the production plant based on a reading provided by the first flow meter; determining a second quantity of the second gas supplied to the exhaust system based on a reading provided by the second flow meter;Triggering of a safety-related control function by a monitoring unit when, depending on the specific initial gas quantity and the specific second gas quantity, insufficient inerting is to be assumed.

[0012] The idea is to provide a monitoring device with two flow measurement units. A first flow measurement unit is connected to a flow meter within a supply line that provides a primary gas for the process (process gas) within the production plant. This first flow measurement unit can continuously measure the quantity of gas supplied to the production plant. In other words, the flow measurement unit determines the quantity of gas introduced at the inlet by measuring the flow rate in the gas supply line to the production plant. A second flow measurement unit is connected to a flow meter located within a supply line to an exhaust system of the production plant. This second flow measurement unit can continuously measure the quantity of inert gas supplied to the exhaust system.The second flow measurement unit also determines the gas quantity based on a flow measurement in a supply line, but in this case in a supply line of the inert gas.

[0013] The two measured gas quantities can be compared to each other to draw conclusions about the inerting in the exhaust system. By defining a threshold value for a specific ratio, a reaction can be triggered if the ratio reaches, or especially falls below, this threshold, indicating insufficient inerting. For example, the measured gas quantities could correlate with a specific hydrogen-oxygen concentration, and the defined threshold could represent a critical hydrogen-oxygen concentration above which an explosive oxyhydrogen gas is present.

[0014] Monitoring of the inerting process in the exhaust system is thus achieved indirectly by determining the quantity of gases supplied to both the production plant and the exhaust system. This has the advantage that the monitoring device can utilize simple flow meters. The actual concentration of the various gases in the exhaust system does not need to be measured. The flow meters can employ simple and readily available sensors, as they can be installed in supply lines that carry only the gases to be measured. Consequently, only the volumetric flow rate needs to be measured, without the need to additionally determine the type and concentration of the gas. Suitable flow meters of various designs are generally known and readily available at low cost from the field of process engineering.The indirect determination of inerting thus enables a cost-effective and reliable determination of inerting even in intelligent systems that dynamically adjust inerting. The aforementioned problem is therefore completely solved.

[0015] In a further embodiment, the device can also include a processing unit configured to calculate a setpoint for the second gas quantity from the first gas quantity determined by the first flow meter. In this way, a control variable for inerting can be directly determined. In particular, the monitoring unit can be configured to execute the safety-related control function if the second gas quantity determined by the second flow meter falls below the setpoint.

[0016] Preferably, the device can also include a volume flow control unit that can be connected to a volume flow controller located in the second supply line to the exhaust gas outlet. The volume flow control unit is configured to regulate the supply of the second gas through the second supply line based on the first gas quantity determined by the first flow meter, i.e., based on a specific setpoint for the second gas quantity. The device can thus be used not only for monitoring but also directly for controlling the inerting process. In this way, existing non-intelligent systems can be easily converted into intelligent systems with dynamic inerting using the proposed monitoring device. The monitoring device can therefore be used particularly effectively.

[0017] The flow controller can have a maximum flow rate, and a value for the maximum possible flow rate of the flow controller can be stored in the flow control unit. The processing unit can be configured to calculate a setpoint for the second gas flow rate from the first gas flow rate determined by the first flow meter. Furthermore, the monitoring unit can be configured to trigger the safety-related control function if the calculated setpoint exceeds the maximum flow rate, i.e., a maximum possible flow rate. In controlled inerting (dynamic inerting), the monitoring can therefore be aligned with the control element used, so that the safety-related control function (safety function) is also triggered if the control element reaches its limits. For example, if...If the required quantity of inert gas exceeds the possible flow rate that the volume flow controller alone, or that the system including the volume flow controller, can provide, this also triggers the safety function. The safety of the entire system can thus be further increased.

[0018] The safety-related control function can include shutting down the supply of the first gas and / or shutting down the entire production plant. Both measures help to quickly and reliably bring the production plant to a safe state in the event of faulty or insufficient inerting. Advantageously, the measure can be limited to a single production unit without having to shut down other plants that may be connected to the same exhaust system. This design can therefore contribute to higher availability of the overall system.

[0019] The safety-related control function can also include initiating an emergency purge, particularly by opening a bypass valve in the secondary supply line. Alternatively or additionally, the control function can thus also perform an emergency purge and utilize a bypass valve, which are typically present in such systems, for example, for manual purging. The bypass valve can be a device independent of the actual control system, allowing the supply of inert gas to be set to the maximum possible level. This measure further enhances safety.

[0020] In one embodiment, the first gas, i.e., the process gas of the manufacturing plant, can be hydrogen, and the inert gas can be nitrogen.

[0021] Furthermore, the processing unit and / or the monitoring unit can be designed with multiple channels and redundancy. This ensures fail-safe operation of the monitoring and / or the execution of the safety-related control function, thus meeting regulatory requirements. Additionally, the processing unit and the monitoring unit can also have a diverse architecture with different hardware. This redundant design allows for continuous testing of the inputs and outputs, as well as continuous comparison of user data, to guarantee fault tolerance.

[0022] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0023] Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Fig. 1 The schematic representation shows a manufacturing plant with an example of a monitoring device for monitoring an inerting process. Fig. 2 shows various further developments of the monitoring device according to Fig. 1 . Fig. 3 A schematic representation shows an example of a procedure for monitoring inerting.

[0024] Fig. 1 Figure 1 shows a production plant with an example of a monitoring device. The monitoring device as a whole is designated here by the reference number 10.

[0025] Production system 12 is an exemplary production system from the field of semiconductor manufacturing and is shown here in a highly simplified form. Production system 12 has at least one chamber 14 within which the manufacturing process takes place. For example, a semiconductor substrate 18 can be placed on a slide 16 in chamber 14, on which various mechanical and chemical manufacturing steps can be carried out to produce a specific semiconductor element.

[0026] The manufacturing system 12 has at least one supply line 20 through which a process gas 22 can be added for manufacturing in chamber 14. The process gas 22 can be used directly for the chemical processing of the semiconductor device or it can be a process gas that helps to create a working environment necessary for manufacturing within chamber 14. As indicated here, the process gas 22 (first gas) can, for example, be hydrogen H₂.

[0027] A flow meter 24 is also arranged in or on the supply line 20 of the process gas 22. The flow meter 24 can be of various designs and provide a value representing the gas supply of the process gas. In particular, the flow meter 24 can be a simple volumetric flow meter that determines a gas supply based on a volumetric flow rate, preferably without having to determine the concentration of the corresponding gas itself.

[0028] Furthermore, the production plant 12 has an exhaust gas tract 26 (exhaust gas discharge) through which the process gases introduced into chamber 14 or any reaction products from chamber 14 can be discharged. The discharged process gases or reaction products are hereinafter referred to as exhaust gases 28. The exhaust gases 28 can be actively or passively discharged from chamber 14 into the exhaust gas tract 26.

[0029] An additional supply line 30 is arranged on the exhaust tract 26, preferably immediately after the exhaust tract 26 exits the production plant 12. An inert gas 32 can be supplied to the exhaust tract 26 via this additional supply line 30 to effect inerting within the exhaust tract 26. In other words, an inert gas is introduced into the exhaust tract 26 to dilute the exhaust gases 28 or to displace certain gases that may be present in the exhaust tract. The inert gas 32 can, as indicated here, be, for example, nitrogen (N₂).

[0030] As in the supply line 20 for the process gas 22, a flow meter 34 is also arranged in or on the second supply line 30. The second flow meter 34 can provide a value corresponding to a gas supply of inert gas. As with the flow meter 24 in the first supply line 20, the second flow meter 34 can also be a simple volumetric flow meter.

[0031] The readings from flow meter 24 and the second flow meter 34 are fed to the monitoring device 10, which has corresponding input ports 36 for this purpose. A first flow meter 38 within the monitoring device 10 can continuously determine a quantity of process gas (first gas quantity) supplied to chamber 14 based on the value provided by the first flow meter 24. Simultaneously, a second flow meter 40 within the monitoring device 10 can determine a quantity of inert gas (second gas quantity) supplied to the exhaust tract 26. A processing unit 42 can convert the gas quantities determined by the flow meters 38 and 40 into a defined ratio. This defined ratio can represent a degree of inerting within the exhaust tract 26, resulting from the supplied gas quantities.It is conceivable, for example, that the supplied gas quantities correlate directly with a hydrogen-oxygen concentration in the exhaust gas tract 26. It is understood that, for determining the defined ratio, the processing unit 42 can take at least one further parameter into account or incorporate correction factors into the determination that are specific to the production plant 12, the exhaust gas tract 26, or the production process. In this way, the monitoring device can be flexibly adapted to different systems.

[0032] A monitoring unit 44 of the monitoring device 10 can continuously compare the ratio determined by the processing unit 42 with a defined threshold value. The monitoring unit 44 triggers a safety-related control function when the determined ratio reaches the threshold value. For example, the monitoring unit 44 triggers the safety-related control function when the determined ratio falls below the threshold value and, consequently, insufficient inerting in the exhaust tract 26 is to be assumed. The monitoring unit 44 thus triggers the safety-related control function depending on the determined gas quantities.

[0033] The safety-related control function 45 serves to reduce the hazard arising from insufficient inerting. The safety-related control function 45 can be configured in different ways, depending on the type of production plant 12 and the process carried out by the production plant 12. In one embodiment, the safety-related function 45 can, for example, include shutting off the gas supply of the process gas in the supply line 20. Alternatively or additionally, the safety-related function 45 can also result in the shutdown of the production plant 12 itself. In yet another embodiment, the safety-related control function 45 can also include an active measure, such as triggering a separate purge of the exhaust gas tract 26.For such purging, a bypass valve (not shown here) can be provided which allows a maximum inflow of inert gas into the exhaust tract 26, independent of any regulation of the inert gas quantity.

[0034] It is understood that the units described above, in particular the division into the various units, are to be understood purely functionally, and that the individual units may also be integrated into one or more components. In one embodiment, for example, the flow measurement units 38, 40, the processing unit 42, and the monitoring unit 44 may be implemented by a central processing unit, such as a central processor (CPU), an ASIC, or a microcontroller.

[0035] Preferably, the individual units are integrated within a common housing to form a single functional control device, which can be arranged in a control cabinet of the production plant 12. The control device can be a modular control device composed of individual hardware and software modules that implement the various tasks of the units described above. The modular control device can include a communication device, e.g., a module bus connecting the individual modules, through which the units are communicatively linked. The control device can also be expandable and perform further control and regulation tasks. Examples of further developments of the in Fig. 1 The monitoring device shown is described with reference to the Fig. 2 explained in more detail below.

[0036] Fig. 2 Figure 10 shows examples of various further developments of the monitoring device described above. The same reference numerals denote the same parts as before.

[0037] The monitoring device 10 according to Fig. 2 differs in particular from the monitoring device 10 by an additional volume flow control unit 46 according to Fig. 1 The volume flow control unit 46 can be connected to a volume flow controller 48, which is arranged upstream in the second supply line 30, i.e., in the direction of flow upstream of the second volume flow meter 34. The volume flow controller 48 can be a controllable valve (mass flow controller (MFC)). In one embodiment, the volume flow controller 48 can, for example, be a control valve with a medium-separated sensor and an integrated proportional-integral (PI) controller. However, the invention is not limited to a specific type of controller. The volume flow controller 48 merely needs to be capable of regulating a volume flow within the second supply line. Therefore, the volume flow controller 48 is also not limited to a single device, as in Fig. 2 depicted, limited, but can include a combination of a variety of different components that together regulate the volume flow.

[0038] The control for the regulation is carried out by the volume flow control unit 46 of the monitoring device 10. The volume flow control unit 46 can be integrated into the monitoring device 10 in the same way as the previously described volume flow measuring units 38, 40, with the difference that the volume flow control unit 46 is coupled to at least one output 50 of the monitoring device 10, via which the volume flow control unit 46 can transmit a control signal to the volume flow controller 48.

[0039] The volume flow control unit 46 can control the volume flow controller 48 according to a setting from the processing unit 42. This setting, in turn, is based on a value for the amount of gas supplied to the production plant 12 via the first supply line 20, and thus on the value for the amount of process gas 22 supplied, determined by the first volume flow measuring unit 38. The setting does not have to correspond directly to the measured value, but can, for example, take into account additional correction factors, tolerances, or other modifications. The setting regulates the supply of inert gas 32 through the second supply line 30 so that sufficient inerting in the exhaust gas tract 26 is ensured. In other words, the monitoring device 10 dynamically adjusts the amount of inert gas to the required quantity.For this purpose, the processing unit 42 can determine a setpoint for the quantity of inert gas 32 required for sufficient dilution or displacement in the exhaust gas tract 26, based on the introduced quantity of process gas 22. The volume flow control unit 46 then regulates the volume flow controller 48 based on this setpoint, thus controlling the inflow of inert gas.

[0040] In a specific example, when using hydrogen as a process gas 22, the volume fraction of hydrogen in the exhaust gas tract must not exceed 3 vol%. Based on the knowledge of the introduced quantity of hydrogen and assuming that up to 100% can be discharged into the exhaust gas tract, the processing unit 42, possibly taking into account other parameters, can determine the quantity of inert gas 32 required to sufficiently dilute the discharged hydrogen in the exhaust gas tract 26 so that the critical volume fraction is not exceeded. The supply of the inert gas can then be controlled via the volume flow control unit 46. In addition to this control, the monitoring device 10 can perform the previously described measurements. Fig. 1 Perform the described monitoring of the inerting and trigger a safety-related response if insufficient inerting is suspected.

[0041] In the monitoring device 10 according to Figur 2 In addition to the previously described monitoring of the inerting process, the control system itself can also be monitored. For example, the monitoring unit 44 can trigger the safety-related response even if a setpoint determined by the processing unit 42 exceeds a maximum possible control state. This maximum possible control state can be limited, for example, by a maximum flow rate of the volume flow controller 48, the maximum possible feed pressure / diameter, etc., and may refer to the maximum amount of inert gas that can be conveyed through the supply line 30 by the volume flow controller 48. In this case, the safety-related response can also be triggered if the required setpoint cannot be reached. Furthermore, additional threshold values ​​can be used to take into account other factors that limit the inerting possibilities.

[0042] The monitoring device 10 can, in particular, be a safety controller. A safety controller can perform control tasks in the same way as a normal controller, for example, a programmable logic controller (PLC) in automation technology. In contrast, however, a safety controller has additional software and hardware features that can ensure the fail-safe execution of certain control functions. These additional features include, for example, a multi-channel, redundant design of the essential processing units and interfaces of the monitoring device 10. This is described in the Fig. 2 indicated by the double representation of each individual unit.

[0043] In addition to redundant design of the individual functional components of the safety controller, the components can also be designed with diversity, for example, by sourcing the redundant components from different manufacturers. This effectively eliminates common-cause failures, further increasing inherent fault tolerance.

[0044] In addition to the monitoring and control of inerting described above, the use of a safety controller allows for the advantageous, fail-safe monitoring of further control aspects, such as tolerance windows, tolerance times, or dead times, thus making them part of the safety circuit. The same applies to corrections for uncertainties caused by deviations in the hardware implementation of the data acquisition system, which can also be implemented safely using a safety controller. In this way, safety can be further enhanced.

[0045] With reference to Fig. 3 The following describes an example of a method for monitoring inerting. The method can be summarized as a process in which, to monitor inerting in an exhaust system, the quantity of process gas supplied to a production plant and the quantity of inert gas supplied to the exhaust system are continuously determined in order to calculate the ratio of these two gases in the exhaust system and, depending on this ratio, trigger a safety-related control function if the ratio reaches a critical value (threshold).

[0046] In detail, the procedure can be used to... Fig. 3 The steps outlined above are shown. The entire procedure is designated by the reference number 1000.

[0047] In a first step, 1001, a monitoring device is provided. The monitoring device comprises a processing unit, a first flow meter, a second flow meter, and a monitoring unit.

[0048] Subsequently (step 1002), the first flow measurement unit is connected to a first flow meter, which is arranged in a first supply line of a first gas to the production plant.

[0049] Furthermore, the second flow measuring unit is connected to a second flow meter, which is arranged in a second supply line of a second gas to the exhaust gas discharge (step 1003).

[0050] The next steps involve determining the initial quantity of the first gas supplied to the production plant during operation, based on a measurement provided by the first flow meter (step 1004), and determining the second quantity of the second gas supplied to the exhaust system, based on a measurement provided by the second flow meter (step 1005). This determination is preferably carried out continuously from the start of the production plant.

[0051] Finally, based on the determined gas quantities, the ratio in which these gases can be present in the exhaust system is calculated (step 1006), without explicitly measuring the actual concentration of the respective gases in the exhaust system. Furthermore, in step 1007, a safety-related control function is triggered depending on the determined gas quantities; that is, the monitoring unit triggers a safety-related control function if the ratio reaches a critical threshold. This threshold can be determined in advance by calculation or empirically, or it can be dynamically adjusted.

[0052] It is understood that the procedure is not limited to the execution shown here, but may include further steps inserted before or after the individual steps. Likewise, individual steps can be repeated, especially continuously, without this being explicitly indicated here.

[0053] In principle, the present invention is not limited by the exemplary embodiments listed here, but is defined solely by the following claims.

Claims

1. Apparatus (10) for monitoring an inertization in an exhaust gas discharge (26) of a production plant (12), comprising: a first flow measurement unit (38); a second flow measurement unit (40); and a monitoring unit (44), wherein the first flow measurement unit (38) is connectable to a first flow meter (24), which is arranged in a first supply line (20) of a first gas to the production plant (12), wherein the second flow measurement unit (40) is connectable to a second flow meter (34), which is arranged in a second supply line (30) of a second gas to the exhaust gas discharge (26), wherein the first flow measurement unit (38) is configured to determine, on the basis of a measured value provided by the first flow meter (24), a first gas quantity of the first gas which is supplied to the production plant (12), wherein the second flow measurement unit (40) is configured to determine, on the basis of a measured value provided by the second flow meter (34), a second gas quantity of the second gas which is supplied to the exhaust gas discharge (26) for the inertization, and wherein the monitoring unit (44) is configured to trigger a safety-related control function (45) if, depending on the determined first gas quantity and the determined second gas quantity, an insufficient inertization is to be assumed.

2. Apparatus according to claim 1, further comprising: a processing unit (42) which is configured to calculate a target value for the second gas quantity from the first gas quantity determined by the first flow measurement unit (38).

3. Apparatus according to claim 2, wherein the monitoring unit (44) is configured to trigger the safety-related control function (45) if the second gas quantity determined by the second flow measurement unit (40) falls below the target value determined by the processing unit (42).

4. Apparatus according to one of claims 1 to 3, further comprising: a volume flow control unit (46) which is connectable to a volume flow controller (48), which is arranged in the second supply line (30) to the exhaust gas discharge (26), wherein the volume flow control unit (46) is configured to control a gas supply of the second gas through the second supply line (30) depending on the first gas quantity determined by the first flow measurement unit (38).

5. Apparatus according to claim 4, wherein the volume flow controller (48) is adjustable to a defined maximum delivery quantity, the value of which can be stored in the volume flow control unit (46), and wherein the apparatus comprises a processing unit (42) which is configured to calculate a target value for the second gas quantity from the first gas quantity determined by the first flow measurement unit (38), and wherein the monitoring unit (44) is configured to trigger the safety-related control function if the calculated target value exceeds the value for the maximum delivery quantity.

6. Apparatus according to one of claims 1 to 5, wherein the safety-related control function (45) includes a shutdown of a supply of the first gas and / or a shutdown of the production plant (12).

7. Apparatus according to one of claims 1 to 6, wherein the safety-related control function (45) includes the initiation of an emergency purge.

8. Apparatus according to claim 7, wherein the emergency purge includes the opening of a bypass valve in the second supply line (30).

9. Apparatus according to one of claims 1 to 8, wherein the first gas contains hydrogen.

10. Apparatus according to one of claims 1 to 8, wherein the second gas is an inert gas.

11. Apparatus according to claim 10, wherein the inert gas is nitrogen.

12. Method (1000) for monitoring an inertization in an exhaust gas discharge (26) of a production plant (12), comprising: - providing a first flow measurement unit, a second flow measurement unit as well as a monitoring unit (1001); - connecting the first flow measurement unit to a first flow meter, which is arranged in a first supply line of a first gas to the production plant (1002); - connecting the second flow measurement unit to a second flow meter, which is arranged in a second supply line of a second gas to the exhaust gas discharge (1003); - determining a first gas quantity of the first gas which is supplied to the production plant, on the basis of a measured value provided by the first flow meter (1004); - determining a second gas quantity of the second gas which is supplied to the exhaust gas discharge for the inertization, on the basis of a measured value provided by the second flow meter (1005); and - triggering a safety-related control function, by a monitoring unit (44), if, depending on the determined first gas quantity and the determined second gas quantity (1007), an insufficient inertization is to be assumed.