Method and apparatus for monitoring the content of a gas

Abstract

Method and apparatus for monitoring the content of a gas Herein, a method for the control of the concentration of a gas in a blow-off line (102), which is connected to a vessel (101) containing the gas is proposed, said method comprising determining a value (201) corresponding to the concentration of the gas in the blow-off line (102) by means of a differential pressure sensor (104), comparing the value (202) corresponding to the concentration of the gas in the blow-off line (102) to a predefined value, and performing (203) at least one measure upon exceeding the predefined value. A corresponding apparatus is also proposed.

Description

[0001] Description

[0002] Method and apparatus for monitoring the content of a gas

[0003] Field

[0004] The present disclosure relates to a method and to an apparatus for monitoring the content of a gas in a blow-off line connected to a vessel containing the gas.

[0005] Background

[0006] To ensure the safety of hydrogen tank systems, safety valves may be installed to protect against overfilling or high pressures. Leaking hydrogen from these safety valves can be passed to a collecting pipe via a blow-off line which routes the leaked hydrogen to a blow-off stack where the hydrogen is diluted with air to reach a safe level. In this configuration it is possible, however, that the concentration of the hydrogen within the blow-off stack reaches a level at which an ignition can occur, which, in particular, poses a safety risk. Similar risks due to a leakage from a corresponding gas tank can also be caused by other, particularly inflammable, gases like methane or propane.

[0007] Summary

[0008] Against this background, a method for monitoring the content of a gas in a blow-off line connected to a vessel containing the gas and a corresponding apparatus are proposed. Embodiments are subject of the dependent claims and the following description.

[0009] The method for monitoring the content of a gas in a blow-off line connected to a vessel containing this gas proposed herein comprises the determination of a value which corresponds to the content of the gas in the blow-off line by means of a differential pressure measurement. This value corresponding to the content of the gas in the blowoff line is compared to a predefined value, and at least one action is initiated if the content exceeds the predefined value. The gas stored in the vessel can be hydrogen or any other flammable gas, the leakage of which would be a potential safety risk, including a risk of fire and / or explosion, and / or a risk of an environmental pollution, particularly, if the gas is toxic.

[0010] By means of a differential pressure measurement, the difference in pressure between two spatial points can be detected. In particular, it is thus possible to compare the pressure within the blow-off line to the pressure outside the blow-off line. A change in pressure within the blow-off line relative to the pressure outside can be an indication for the gas leaking from the vessel into the blow-off line.

[0011] In particular, the value corresponding to the concentration of the gas in the blow-off line can be determined continuously, such that the response time to a potential leakage of the gas into the blow-off line is reduced. Thus, also the at least one action can be initiated promptly after the detection of the potential leakage, such that a safe operation of the system can be established.

[0012] With the method proposed herein, the safety of personnel and objects in the surrounding environment of the vessel, which is containing the gas, can be increased. In particular, the vessel can be a storage vessel for hydrogen in a hydrogen refuelling system. An increased safety of these refuelling systems could contribute to the overall acceptance of these systems and an increase of the trust in hydrogen as an energy source. The automated execution of safety measures, like the introduction of an inertization gas to the blow-off line, minimizes the risk of human errors and reduces the response time to leakages. Due to the increase of the safety of the system, the compliance of safety regulations and safety standards can be ensured.

[0013] The method according to the invention can be implemented in industrial applications, in which large amounts of hydrogen are stored and / or transported, like in the chemical industry, metallurgy, electrolysis, or in industrial hydrogen refuelling systems. The application in mobile hydrogen tanks is particularly relevant with regard to the supply chain for fuel cell powered vehicles or mobile power generation units.

[0014] Depending on the specific requirements and conditions of the application, the parameters and settings of the system can be adapted and customized. For instance, the predefined value of the concentration of the gas in the blow-off line can be adjusted, or the flow rate of the inertization gas can be adapted.

[0015] The method according to the invention can also be included as a part of other safety measures. For instance, the system can be part of a safety system comprising fire detector, gas detectors, and / or emergency shutdown systems.

[0016] In an embodiment, the at least one action, which is initiated if the concentration of the gas in the blow-off line exceeds the predefined value, is issuing an alarm and / or introducing an inertization gas into the blow-off line.

[0017] Introducing an inertization gas into the blow-off line gives rise to a dilution of the concentration of the gas in the blow-off line, such that the concentration of the gas in the blow-off line may fall below a critical value, e.g. being in a range in which no combustion of the gas can occur or is unlikely. Thus, the safety of personnel operating in the vicinity of the vessel can be increased, and expensive equipment in the environment of the vessel can be prevented from being damaged.

[0018] By issuing an alarm, an operator can be informed, who could then confirm the validity of the alarm and, in case of the alarm being valid, initiate at least one safety measure. In particular, the operator can trigger the introduction of the inertization gas into the blow-off line, or initiate the shutdown of the system.

[0019] For triggering the alarm and / or for automatically introducing the inertization gas, a control system can be provided, which the differential pressure sensor and a controllable inlet to the blow-off line are coupled to or are part of. The control system may control the controllable inlet based on the differential pressure provided by the differential pressure sensor, for instance. In particular, the control system also allows safety monitoring and logging.

[0020] In another embodiment, the inertization gas can be introduced to the blow-off line manually and / or automatically.

[0021] A manual introduction of the inertization gas can be performed by an operator, for instance, who can be notified by an alarm, which is triggered if the concentration of the gas in the blow-off line exceeds a predefined value. Introducing the inertization gas manually is advantageous, as the operator can confirm the validity of the alarm first, such that, in case of a potential false alarm event, no action is initiated. In particular, this gives rise to a particularly resource efficient usage of the inertization gas, thus being more cost effective.

[0022] Automatically introducing the inertization gas does not require an operator to perform the introduction of the inertization gas. Thus, sources of error which are caused by manual failure can be avoided. In particular, manual failures may include inattention or absence of the operator during an alarm, and / or an incorrect execution of safety measures. An automatic introduction of the inertization gas is therefore more reliable and hence also safer compared to a manual introduction of the inertization gas. Additionally, in case of the inertization gas being introduced automatically, the response time to leakages is minimized and human intervention in dangerous situations is limited.

[0023] In another embodiment, the gas in the vessel has a density which is different from the density of air. Thus, a leakage of the gas into the blow-off line can be detected by a change in pressure level between the inside and the outside of the blow-off line, in particular by means of the differential pressure sensor.

[0024] In another embodiment, the inertization gas can be an inert gas, like nitrogen, helium or argon, or a combination thereof. Using an inert gas for the dilution of the gas in the blow-off line is advantageous, as no additional risk of combustion and / or ignition of the inertization gas is introduced.

[0025] In another embodiment, the concentration of the gas in the blow-off line is additionally determined by a gas detector and / or a detector which is based on a thermal method for the detection of the gas. Gas detectors may include electrochemical, infrared, photoionization, or metal oxide semiconductor (MOS) gas detectors, which allow the detection of specific gases, instead of a pressure difference. In case of thermal methods for the detection, a gas can be determined based on its thermal conductivity. This method is particularly cost efficient, in particular compared to other gas detectors. Also, the implementation of additional means to determine the concentration of the gas in the blow-off line allows a confirmation and / or validation of the measurement of the concentration of the gas, which is based on the differential gas sensor.

[0026] In another embodiment, a safety valve is attached to the vessel containing the gas. The safety valve is arranged such that it opens to the blow-off line.

[0027] In particular, the safety valve prevents the development of an overpressure within the vessel containing the gas. In case of an overpressure within the vessel, the safety valve opens and partially releases the containing gas, such that the pressure within the vessel is reduced. The safety valve may contain a mechanical spring, which is used to keep the safety valve closed, until the pressure within the vessel exceeds a predefined pressure value. It is possible that the sealing material of the safety valve gets deformed over time, due to the constant pressure of the mechanical spring, which in combination with dirt may lead to small leaks. The gas leaking from the vessel can ignite, representing a significant safety risk. The determination of the concentration of the gas in the blow-off line and the implementation of safety measures according to the invention allow a safe operation of the vessel containing the gas.

[0028] In another embodiment, a first end of the blow-off line is attached to the vessel, and its second end is located above the first end. The blow-off line may be arranged vertically or essentially vertically, but embodiments disclosed herein are not limited to such an arrangement. In this configuration, the gas, which may leak from the vessel, can be effectively removed via the blow-off line, in particular if the density of the gas is lower than that of the atmosphere surrounding the vessel, e.g. air.

[0029] In another embodiment, an inlet to the blow-off line allows the introduction of the inertization gas to the blow-off line via a controllable valve. Thus, the inertization gas can be introduced to the blow-off line, such that the inertization gas dilutes the concentration of the gas within the blow-off line. This controllable valve can be operated manually and / or automatically. In case of a manual operation, an operator can control the introduction of the inertization gas to the blow-off line if an alarm was triggered, for instance. Automatic operation of the controllable valve does not require the permanent presence of an operator and limits possible sources of human error. The present invention further provides an apparatus for monitoring the content of a gas in a blow-off line which is connected to a vessel containing the gas. The apparatus comprises a safety valve which is attached to the vessel containing the gas and which opens to the blow-off line, at least one differential gas sensor, which is configured to determine a value corresponding to the concentration of the gas in the blow-off line, and an inlet for an inertization gas, which is configured to be connected to the blow-off line via a controllable valve.

[0030] This apparatus can in particular be configured to perform a method according to an embodiment of the invention.

[0031] As to further details and advantages of such an apparatus, reference is made to the explanations above in regarding the method proposed herein and its different embodiments. Particularly, such an apparatus may, in embodiments as proposed herein, comprise means adapted to perform a method according to any of the embodiments as discussed herein.

[0032] Further advantages and embodiments of the invention will be apparent from the description and the accompanying drawing.

[0033] The invention is shown schematically in the drawing by means of an example of an embodiment and is described below with reference to the drawing.

[0034] Figures

[0035] Fig. 1 shows an embodiment of an apparatus which a method according to an embodiment of the invention can be executed with.

[0036] Fig. 2 show a flow diagram of a method according to an embodiment of the invention.

[0037] Embodiments

[0038] In the Figures, elements of identical, essentially identical, functionally comparable, or technically compatible function and / or purpose may be identified with identical reference numerals, and repeated explanations may be omitted for reasons of conciseness. Explanations herein relating to devices, apparatus, arrangements, systems, etc., according to certain embodiments disclosed herein likewise may apply to methods, processes, procedures, etc. according to corresponding embodiments.

[0039] The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claimed invention.

[0040] Various embodiments as disclosed herein may suitably comprise, consist of, or consist essentially of, appropriate and technically sensible combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future, particularly when encompassed by the scope of the independent claims.

[0041] Fig. 1 schematically illustrates an apparatus 100 which can be configured to execute a method according to an embodiment of the invention.

[0042] The apparatus comprises a vessel 101 which contains a gas. The vessel 101 can in particular be a storage or transport vessel for hydrogen. A blow-off line 102 is connected to the upper part of the vessel 101 , such that, in particular, the connection between these two elements does not allow gas to pass through. A first end of the blow-off line 102 is therefore attached to the vessel 101 , while a second end of the blow-off line 102 is located above the first end. The second end of the blow-off line 102 is open, such that the inside of the blow-off line 102 is connected to the atmosphere surrounding the apparatus 100.

[0043] The inside of the vessel 101 is connected to the inside of the blow-off line 102 via a safety valve 103. This safety valve 103 opens, if the pressure within the vessel 101 exceeds a predefined pressure value, in which case the gas contained in the vessel 101 partially flows into the inside of the blow-off line 102. The pressure within the vessel 101 is thus reduced.

[0044] A leakage of the safety valve 103 may also lead to an increased concentration of the gas within the blow-off line 102. If this concentration gets too high, this may give rise to an ignition and / or combustion of the gas within the blow-off line 102, which poses a significant safety hazard.

[0045] By means of a differential gas sensor 104, the pressure inside the blow-off line 102 relative to the pressure outside can be determined. In case of the gas flowing from the vessel 101 into the blow-off line 102, the pressure inside the blow-off line changes relative to the pressure outside. This pressure difference can be related to a concentration of the gas, which can be used as an indication of a leakage of the safety valve 103.

[0046] If the concentration of the gas within the blow-off line 102 exceeds a predefined value, at least one action is initiated, which may include triggering an alarm and / or introducing an inertization gas to the blow-off line 102. The inertization gas can be introduced from a vessel containing the inertization gas 105 to the blow-off line 102 via a controllable valve 106. Introducing the inertization gas to the blow-off line 102 gives rise to a dilution of the gas within the blow-off line 102, such that the concentration of the gas within the blow-off line 102 falls below a critical value and the risk of ignition and / or combustion is reduced. The inertization gas can be an inert gas, like nitrogen, helium and / or argon, for instance.

[0047] The controllable valve 106 can be operated manually and / or automatically. The automatic control can be performed by a control system 107, which is configured to receive the data collected by the differential pressure sensor and control the controllable valve 106. The controllable valve 106 can be controlled based on the concentration of the gas within the blow-off line 102, and allows setting the flow rate of the inertization gas into the blow-off line 102.

[0048] Further, the control system 107 can be configured to trigger an alarm and / or send a notification to an operator, who then may execute manual safety measures, and / or verify the alarm event. The control system 107 may also be connected to other safety systems, like fire or gas detectors, and / or emergency shutdown systems. Thus, the control system 107 can act, based on the feedback of the other safety systems, or send instructions to other safety systems, such that an emergency shutdown for other systems is triggered, for instance

[0049] In Fig. 2, a schematic flow diagram 200 of an embodiment of the method according to the invention is shown.

[0050] In a first step 201 , the pressure difference between the inside of the blow-off line 102 with respect to the outside of the blow-off line 102 is determined by means of the differential pressure sensor 104.

[0051] This pressure difference is compared to a predefined value in a next step 202. If the pressure difference is below the predefined value (N), the determination of the pressure difference, i.e. step 201 , is repeated.

[0052] If the pressure difference exceeds the predefined value (Y), on the other hand, at least one action is initiated in step 203. In this case, a predefined amount of nitrogen is introduced to the blow-off line 102 via the controllable valve 106.

[0053] Subsequently, the pressure difference is determined again by means of the differential pressure sensor 104, such that a continuous feedback loop is established. In particular, step 203 is repeated, until the pressure difference is below the predefined value

Claims

Patent Claims1. A method for monitoring the content of a gas in a blow-off line (102), which is connected to a vessel (101) containing the gas, said method comprising: determining (201) a value corresponding to the concentration of the gas in the blow-off line (102) by means of a differential pressure sensor (104), comparing (202) the value corresponding to the concentration of the gas in the blow-off line (102) to a predefined value, characterized in that an inertization gas is introduced to the blow-off line (102) upon exceeding the predefined value.

2. The method according to claim 1 , wherein an alarm is issued upon exceeding the predefined value.

3. The method according to claim 1 , wherein the inertization gas is introduced to the blow-off line (102) manually and / or automatically.

4. The method according to any one of the preceding claims, wherein the density of the gas in the vessel (101) is different from the density of air.

5. The method according to any one of the preceding claims, wherein the inertization gas is an inert gas.

6. The method according to any one of claims 1 to 4, wherein the inertization gas is selected from the group of nitrogen, helium and argon.

7. The method according to any one of the preceding claims, wherein the value corresponding to the concentration of the gas in the blow-off line (102) is determined by a member of the group containing a gas detector and a detector based on a thermal method for the detection of the gas.

8. The method according to any one of the preceding claims, further comprising: providing a safety valve (103), which is attached to the vessel (101) containing the gas, and which opens to the blow-off line (102).

9. The method according to claim 8, wherein an end of the blow-off line (102) is attached to the vessel (101), and a second end of the blow-off line (102) is located above the end of the blow-off line (102).

10. The method according to any one of the preceding claims, further comprising: providing an inlet for the inertization gas to the blow-off line (102), which is configured to be connected to the blow-off line (102) via a controllable valve (106).

11. An apparatus (100) for the control of the concentration of a gas in a blow-off line (102), which is connected to a vessel (101) containing the gas, comprising: a safety valve (103), which is attached to the vessel (101) containing the gas, and which opens to the blow-off line (102), at least one differential gas sensor (104), which is configured to determine a value corresponding to the concentration of the gas in the blow-off line (102), and an inlet for an inertization gas, which is configured to be connected to the blowoff line (102) via a controllable valve (106).

12. The apparatus (100) according to claim 11 , which is configured to perform a method according to any one of claims 1 to 10.

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