GAS DISTRIBUTION NETWORK WITH A MEASURING DEVICE FOR DETERMINING THE CALORIFICIAL VALUE OF A GAS STREAM

Description

[0001] The invention relates to a gas distribution network with a gas pipeline system of interconnected gas pipelines and a measuring device.

[0002] Measuring devices for determining the calorific value of gas streams are generally known from the state of the art and are used at central feed-in points of a local gas distribution network from a supra-regional gas network to measure the calorific value of the gas stream fed in. Determining the calorific value is necessary to determine the associated energy quantity (in kWh) from the gas volume (in m3<) that a gas consumer connected to the gas distribution network has taken from the gas distribution network, which is typically measured with a volume flow meter at the gas consumer's connection to the gas distribution network. This energy quantity is then used as the basis for billing.

[0003] According to the current state of the art, gas chromatographs, combustion calorimeters or absorption spectrometers are used to determine the calorific value. With a gas chromatograph, the proportions of the individual gas components are measured, and from this, conclusions are drawn about the calorific value of the gas mixture as a whole. With a combustion calorimeter, a sample quantity of gas is burned, if necessary catalytically, and the energy released is measured, from which the calorific value can then be determined in relation to the gas and air inflow. With an absorption spectrometer, the proportions of the individual gas components are determined using the light absorption of the gas components, and from this conclusions are drawn about the calorific value of the entire gas mixture. However, these measuring methods are very complex, so that corresponding measuring devices usually cost more than EUR 30,000, sometimes even more than EUR 100,000, and are therefore generally only used for large-scale measurement ortransport network level can be used cost-optimally.

[0004] In order to keep the operating and associated billing costs for a local gas supply network low, such devices are currently only used at central points in natural gas networks due to their high acquisition costs, in particular at the previously mentioned central feed-in points from a supra-regional gas network.

[0005] Furthermore, various methods and devices for determining a calorific value or a Wobbe number of a gas are known from DE 199 21 167 A1, DE 10 2016 014 151 A1 and DE 693 16 643 T2.

[0006] Furthermore, EP2045507A1 discloses a gas distribution network with a decentralized gas feed-in system and with a measuring device connected to a gas line, comprising a calorific value sensor and a control device which controls the gas feed-in depending on the determined calorific value.

[0007] The increasing decentralization of gas supply, particularly the increase in decentralized gas injection plants connected to local gas supply networks, such as hydrogen or biogas injection plants, is leading to greater fluctuations in gas quality, particularly with regard to hydrogen concentration and thus calorific value. The specific calorific value of hydrogen, for example, is significantly lower than the specific calorific value of methane. In addition, there are greater fluctuations in gas quality within a local gas supply network, which can no longer be adequately reflected by the calorific value measurement devices provided at central locations.

[0008] Against this background, the present invention is based on the object of economically improving the measurement of gas quality even in the case of decentralized gas feed into a gas distribution network.

[0009] This object is achieved according to the invention by the use of a measuring device for determining the calorific value of a gas flow in a gas line, in particular a gas distribution network, according to patent claim 1, with a calorific value sensor which is designed to measure a value for the calorific value of a gas in a gas line, and with a control device which is designed to determine a value for the calorific value of the gas flow from the measured value for the calorific value of the gas flow and optionally further measured values ​​obtained via the gas flow.

[0010] It has been determined that the use of pellistors or other commercially available gas sensors for detecting gaseous substances, particularly gas sensors that convert the thermal and / or chemical information of the gas to be measured into an electrically usable signal, which is then used in the control system to determine the calorific value, makes it possible to produce measuring devices for determining the calorific value of a gas stream in a gas pipeline that are significantly more cost-effective than the gas chromatographs and gas calorimeters previously used. This enables the decentralized use of such measuring devices at reasonable costs, particularly near decentralized gas injection facilities or near gas consumers connected to the gas distribution network, in order to determine the calorific value of the injected or withdrawn gas at each consumption point.

[0011] The calorific value sensor is preferably a pellistor or a gas sensor for detecting gaseous substances to measure thermal and / or chemical information of a gas. In particular, the gas sensor can be a solid-state sensor for determining the specific calorific value or the Wobbe number.

[0012] The measuring device can in particular be a device with a housing in which the sensors and the control device are arranged. The housing is preferably sealable, for example with a lead seal, to prevent tampering. The measuring device can for example have a gas inlet and a gas outlet to guide the gas flow from a gas line through the device and can for example have an air inlet to mix a defined air stream with the natural gas and have it detected by the sensor. Furthermore, the housing preferably has a gas outlet for the gas-air mixture detected by the sensor so that after the measurement it can be safely fed into the gas stream of the customer's system and used there as intended, e.g. for heat generation, power generation or product manufacturing. The measuring device is preferably designed in accordance with the applicable explosion protection requirements.

[0013] The housing of the measuring device can accommodate in particular the control device, the calorific value sensor, a gas sensor for measuring the absence of gas in the ambient air, an air supply for the defined air-gas mixture, a measuring chamber in which the calorific value sensor, for example the pellistor and / or possibly further gas sensors are arranged, a housing ventilation, interfaces for connecting existing sensors for ambient temperature measurement, gas temperature measurement, volume flow measurement, ambient pressure measurement, gas pressure measurement, air humidity measurement and / or gas humidity measurement or the respective sensors if they are not present, and / or a data memory, for example for 5-minute values ​​of all sensors for two years, a power supply, preferably via a PV module, a power distribution network and / or interfaces for data readout, e.g. with WLAN or Bluetooth standard interfaces or GPRS up to 5G data transmission standard.

[0014] A measuring device with a housing, in particular in a compact, preferably miniaturized design, is particularly suitable for installation of the measuring device at a house connection, in a gas pressure control system of the gas distribution network and / or in a measuring system of the gas distribution network.

[0015] Alternatively, the sensors of the measuring device can also be integrated directly into a gas line and connected to the control unit of the measuring device, which can be located inside or outside the gas line. In this case, the individual sensors are preferably located in suitable spatial proximity to one another, in particular in a section of a gas line without branches between the individual sensors.

[0016] The pellistor comprises, in particular, a heating wire which, during operation, is heated by the flow of current, for example to a temperature of over 800°C. The gas to be analyzed combusts on the hot wire, and the resulting heat leads to a change in the heating wire temperature, which in turn causes a change in the resistance of the heating wire. By measuring this change in resistance, conclusions can be drawn about the energy released during the combustion process and thus a value for the specific calorific value or Wobbe number of the gas to be analyzed can be determined. The pellistor can have a catalyst, for example platinum oxide, in the area of ​​the heating wire in order to achieve combustion of the gas to be analyzed at lower heating wire temperatures, for example at temperatures above 400°C.

[0017] In addition to pellistors, other gas sensors available on the market are also suitable for determining the calorific value of a gas and are significantly cheaper than the gas chromatographs and gas calorimeters previously used at central transfer points from the transport network to the distribution network.

[0018] Furthermore, the above-mentioned object is achieved by a gas distribution network according to claim 10, comprising a gas pipeline system of interconnected gas pipelines and comprising the previously described measuring device or an embodiment thereof, wherein the measuring device is arranged and configured to determine the calorific value of a gas flow through one of the gas pipelines of the gas pipeline system.

[0019] The significantly lower costs of the measuring device described above compared to previously used gas chromatographs and calorimeters make it possible, in particular, to provide the measuring devices at decentralized locations in the gas distribution network, for example in the area of ​​a decentralized feed-in system, in the area of ​​a (decentralized) gas consumer and / or at nodes of the gas pipeline system.

[0020] This enables decentralized monitoring of the gas in the gas pipeline system, so that the decentralized gas feed from hydrogen or biogas feed-in plants can also be monitored.

[0021] In this context, gas is understood to mean, in particular, a gas mixture with the properties specified in DVGW Worksheet G260, or a mixture of biogas, synthetically produced methane, or hydrogen with gases specified in DVGW Worksheet G260. The gas mixtures present in the gas pipeline system and to be measured with the measuring device can therefore deviate significantly from the gas specified in DVGW Worksheet G260. This deviation necessitates decentralized gas quality measurement. The measuring device described above and the gas distribution network with such measuring devices thus enable natural gas distribution network operators, in particular, to switch to more climate-friendly gases for heat generation for end customers.

[0022] Various embodiments of the measuring device and the gas distribution network are described below. The individual embodiments apply independently to both the measuring device and the gas distribution network. The individual embodiments can also be combined with one another.

[0023] In one embodiment, the measuring device is configured to obtain a measured value for the gas pressure in the gas line, and the control device is further configured to determine the calorific value of the gas stream as a function of the measured gas pressure value. In this way, the actual current gas pressure, in particular instead of a predetermined average supply pressure, can be taken into account when calculating the calorific value, so that the calorific value of the gas stream can be determined more accurately.

[0024] To obtain a measured value for the gas pressure in the gas line, the measuring device can, in particular, comprise a pressure sensor configured to measure a value for the gas pressure in the gas line. Alternatively, the measuring device can also comprise a data interface for connecting the measuring device to an external pressure sensor, and the control device can be configured to obtain the measured value for the gas pressure in the gas line via the data interface. In this way, an existing pressure sensor can be used, eliminating the need for a separate pressure sensor for the measuring device.

[0025] According to one embodiment, the control unit of the measuring device can be configured to monitor the obtained gas pressure value for when it falls below a predetermined minimum gas pressure and to trigger the output of a warning message when the minimum gas pressure is undershot. In this way, the measuring device can also detect a possible leak or pipe break in the gas pipeline system, or an act of tampering with the gas pipeline system. This functionality is particularly suitable for the measuring devices described because their cost-effective production allows for use at multiple locations in the gas distribution network.

[0026] In a further embodiment, the measuring device is configured to obtain a measured value for the gas temperature in the gas line, and the control device is further configured to determine the calorific value of the gas flow as a function of the measured gas temperature. In this way, the actual current gas temperature can be taken into account when calculating the calorific value, in particular instead of a predetermined average gas temperature, so that the calorific value can be determined more accurately.

[0027] To obtain a measured value for the gas temperature in the gas line, the measuring device can, in particular, comprise a temperature sensor configured to measure a value for the gas temperature in the gas line. Alternatively, the measuring device can also comprise a data interface for connecting the measuring device to an external temperature sensor, and the control device can be configured to obtain the measured value for the gas temperature in the gas line via the data interface. In this way, an existing temperature sensor can be used, eliminating the need for a separate temperature sensor for the measuring device.

[0028] In a further embodiment, the measuring device is configured to obtain a measured value for the gas volume flow in the gas line, and the control device is further configured to determine the calorific value of the gas flow based on the measured value for the gas volume flow. In this way, the actual current gas volume flow can be taken into account when calculating the calorific value, so that the calorific value of the current gas volume flow can be determined by integrating the gas quantity conveyed with the gas volume flow.

[0029] In order to obtain a measured value for the gas volume flow in the gas line, the measuring device can, in particular, comprise a volume flow sensor, for example a dial meter or a diaphragm gas meter, which is configured to measure a value for the gas volume flow in the gas line. Alternatively, the measuring device can also comprise a data interface for connecting the measuring device to a volume flow sensor, and the control device can be configured to obtain the measured value for the gas volume flow in the gas line via the data interface. In this way, an existing volume flow sensor can be used, eliminating the need for a separate volume flow sensor for the measuring device.

[0030] In particular, domestic connections generally have a respective volume flow sensor, typically a diaphragm gas meter, to determine the amount of gas withdrawn from the gas distribution network for billing purposes. Accordingly, the data interface can preferably be configured for connection to a volume flow sensor of a domestic connection.

[0031] For example, so-called smart meters are now being installed at house connections. The data interface of the measuring device can be configured for connection to such a smart meter in order to receive measured values ​​from an existing volume flow sensor via the smart meter.

[0032] In one embodiment, the measuring device has an electronic counter evaluation, in particular with a scanner unit, which is designed to evaluate the counter of an analog gas meter in order to obtain a value for the gas volume flow.

[0033] In a further embodiment, the measuring device has a data interface for remote data transmission. The data interface can in particular be configured to directly establish a remote data transmission connection, for example via a mobile radio network. Alternatively, the data interface can also be configured for indirect communication via a remote data transmission connection established by another component, for example as a network interface for connection to a local network with an internet connection. The control device is preferably configured to send information about the determined calorific value, in particular the determined value for the calorific value or information as to whether the determined value for the calorific value exceeds or falls below a predetermined limit, via the data interface, in particular to an external server, for example a central server of the gas distribution network control authority.

[0034] In a corresponding embodiment of the gas distribution network, it preferably comprises a central server configured to receive information about the calorific value measured by the individual measuring devices of the gas distribution network and to control the gas distribution network based on this information. This enables centralized network control based on the decentrally determined information about the respective calorific value.

[0035] In a further embodiment, the measuring device has a data memory, and the control device is configured to store data records associated with the respective point in time, containing information about the determined calorific value, in particular the determined value for the calorific value or information as to whether the determined value for the calorific value exceeds or falls below a predetermined limit, on the data memory. For example, the data record can include a timestamp for the respective point in time. In this way, the development of the determined gas quality can be archived, for example, for later evaluation. The control device can, for example, be configured to store a corresponding data record periodically, for example every 5 minutes. The data memory is preferably large enough to store periodically stored data records over a period of at least 2 years.

[0036] In another embodiment, the measuring device has a grid-independent power supply, for example, comprising a rechargeable battery and optionally a photovoltaic (PV) panel. This ensures the operation of the measuring device even in the event of a power outage. Furthermore, this allows for easy use of the measuring devices in locations where a direct connection to the power grid is neither possible nor practical.

[0037] In a further embodiment, the measurement accuracy of the measuring device's sensors and the calculation accuracy of the control device are configured to meet the measurement accuracy requirements of DVGW Worksheet G685 and / or the calibration law applicable at the site of use. This allows the calorific values ​​determined by the measuring device to be used directly for billing purposes.

[0038] According to the invention, a decentralized gas feed system is connected to a gas line of the gas pipeline system, wherein the measuring device is configured to determine the calorific value of the gas flow fed into the gas pipeline system by the gas feed system. For this purpose, the measuring device is preferably arranged in the region of the connection point of the decentralized gas feed system to the gas pipeline system. The gas feed system can be, for example, a decentralized hydrogen feed system or a biogas feed system.

[0039] In this way, the calorific value of the gas fed into the gas distribution network can be determined, allowing the calorific value in the gas distribution network to be monitored decentrally. According to the invention, the control device is configured to use the determined calorific value to determine information about the composition of the gas stream, namely the hydrogen content. The calorific values ​​of natural gas, biogas, and hydrogen differ, so that the hydrogen and / or methane content can be estimated, extrapolated, or reliably determined using a recognized calibration method based on the calorific value.

[0040] According to the invention, the decentralized gas feed system is configured to control the gas feed into the gas pipeline system depending on the calorific value of the gas flow determined by the measuring device. According to the invention, the gas feed into the gas pipeline system can be reduced or stopped, for example, by shutting down the gas feed system, if the determined hydrogen content exceeds a predetermined maximum limit, for example, 30 vol.%.

[0041] This allows the composition of the gas in the gas distribution network to be regulated in a decentralized manner. This prevents the hydrogen content of the gas from increasing above a permissible level. In this embodiment, the decentralized feed-in can, for example, take place directly at or in close proximity to the house connection. This makes micro-feed-in systems possible. Due to the decentralized feed-in of the decentrally generated gas, the manufacturer and distributor must ensure a defined product quality and can verify this, for example, using the measuring device described here and adapt it to a specified product quality level by controlling the feed-in quantity of the decentrally generated gas.In a further embodiment of the gas distribution network, a gas consumer is connected to a gas line of the gas pipeline system, in particular via a house connection, wherein the measuring device is configured to determine the calorific value of the gas flow supplied to the gas consumer. In this way, the calorific value of the gas flow supplied to the gas consumer can be determined decentrally, thus improving the accuracy of billing in the event of fluctuating gas calorific values ​​in the gas pipeline system.

[0042] In a further embodiment, the gas consumer is configured to control the gas withdrawal from the gas pipeline system or a combustion process operated with the withdrawn gas depending on the calorific value of the gas flow determined by the measuring device. In this way, the gas consumer can, for example, draw precisely the required combustion output from the gas distribution network. By controlling a combustion process, the combustion process can be adapted to the gas calorific value, so that the combustion process can run more optimally and economically. In this way, for example, the combustion control in a condensing boiler or in a decentralized combined heat and power plant can be optimized.

[0043] When controlling the combustion process, for example, a shutdown, particularly an emergency shutdown, of the combustion plant, such as a heating system, can also occur if the calorific value of the gas or a property determined by it, namely the hydrogen content, lies outside a specified operating range. This can increase the safety of the combustion plant, for example, against damage or destruction due to incorrect gas properties, and its operation.

[0044] To increase safety, in a further embodiment the measuring device can have a measuring sensor for determining a value for the concentration of a flammable gas outside the gas line, in particular in the ambient air, and the control device can be configured to trigger the output of a warning message if the determined value for the concentration of a flammable gas outside the gas line exceeds a predetermined limit. This embodiment is particularly advantageous if the measuring device is arranged in the area of ​​a house connection. In this way, the occupants of the house or another building can be warned of a gas leak. The warning message can be, for example, an acoustic signal or a warning SMS, which is sent, for example, via an SMS service when the measuring device outputs a corresponding warning signal via a data interface.

[0045] Further features and advantages of the measuring device and the gas distribution network will become apparent from the following description of exemplary embodiments, with reference to the attached drawing.

[0046] In the drawing show Fig. 1 shows a local gas distribution network from the prior art, Fig. 2 shows a first embodiment of the measuring device, Fig. 3 shows a second embodiment of the measuring device, Fig. 4 shows a first embodiment of the gas distribution network and Fig. 5 shows a second embodiment of the gas distribution network.

[0047] Fig. 1 shows a local gas distribution network of the prior art. The gas distribution network 2 comprises a gas pipeline system 4 consisting of interconnected gas pipelines 6, to which various gas consumers 8 (rectangles) are connected. The gas distribution network 2 is connected at a central feed-in point 10 to a supra-regional gas network 12, from which Fig. 1 a long-distance gas pipeline 14 is shown.

[0048] The quality of the gas fed from the long-distance gas pipeline 14 into the gas distribution network 2 is determined by a measuring device 16 (circuit). To determine the calorific value of the injected gas, the central measuring device 16 comprises a gas chromatograph or a calorimeter. Because these devices are very expensive, only a single measuring device 16 is provided in the gas distribution network 2, in the area of ​​the central feed-in point 10.

[0049] In gas distribution networks that are fed centrally from the supra-regional gas network 12 alone, a single measuring device 16 in the area of ​​the central feed-in point 10 is typically sufficient to determine the gas quality, in particular the calorific value, in the local gas distribution network 2 with sufficient accuracy.

[0050] Recently, however, more and more decentralized feed-in plants (triangles) have been connected to local gas distribution networks, such as hydrogen or biogas feed-in plants, which change the gas composition in the gas distribution network. Decentralized feed-in can even lead to different gas compositions in different parts of the gas distribution network at the same time.

[0051] In these cases, a single measuring device 16 at the central feed-in point 10 will generally no longer be sufficient to determine the gas quality in the gas distribution network with sufficient accuracy, which may, for example, lead to incorrect billing to the gas consumers.

[0052] Fig. 2 shows a first embodiment of the measuring device in a schematic representation. The measuring device 22 has a housing 24 with a gas inlet 26 and a gas outlet 28. The measuring device 22 can be connected to a gas line 30 via the gas inlet 26 and the gas outlet 28 in such a way that a gas stream 31 flowing in the gas line 30 is guided through the measuring device 22.

[0053] The housing 24 houses a control device 32 and several sensors, namely a calorific value sensor 34, a pressure sensor 36, a temperature sensor 38, and a volume flow sensor 40, which are connected to the control device 32. The sensors 34, 36, 38, and 40 are arranged to measure values ​​for the calorific value, the gas pressure, the gas temperature, and the gas volume flow, respectively, of the gas stream 31 passed through the housing 24. The sensors 36, 38, and 40 are arranged directly in the gas stream 31, which is guided through the measuring device 22 during operation. The calorific value sensor 34, on the other hand, is preferably not arranged directly in the gas stream 31, but in a measuring chamber 33 accommodated in the housing 24. During operation, gas from the gas stream 31 enters the measuring chamber 33 via a feed line 35, which is preferably controlled by a controllable valve (not shown), so that the calorific value sensor 34 can determine a value for the Wobbe number orfor the specific calorific value of the gas. If a pellistor is used as the calorific value sensor 34, this typically requires a defined gas-air mixture for accurate calorific value determination. This defined gas-air mixture can be specifically adjusted in the measuring chamber 33 by controlling the supply line 35 and a further, likewise controllable, air supply line 37. After the measurement, the gas-air mixture can be fed back into the gas stream 31 via a discharge line 39.

[0054] It is also conceivable to access existing sensors. For this purpose, the measuring device 22 has a data interface 42 that can be connected to a sensor 44 arranged outside the measuring device 22, so that a value measured by the sensor 44 can be received by the control device 32 via the data interface 42.

[0055] If the measuring device 22 is installed, for example, at a house connection, the sensor 44 can be the volume flow sensor of the house connection. This eliminates the need for the volume flow sensor 40 of the measuring device, allowing the measuring device 22 to be manufactured more compactly and cost-effectively.

[0056] The calorific value sensor 34 can be, in particular, a pellistor or another gas sensor for detecting gaseous substances, in particular a gas sensor that converts thermal and / or chemical information of the gas to be measured into an electrically usable signal. Such sensors are very compact and inexpensive, so that the manufacturing costs for the measuring device 22 are significantly lower than for the measuring device 16 known from the prior art. Fig. 1 can be drastically reduced.

[0057] The control device 32 is configured to determine a value for the calorific value of the gas stream 31 from the value for the gas calorific value measured by the calorific value sensor 34, such as the Wobbe number, from the value for the gas pressure p measured by the pressure sensor 36, from the value for the gas temperature T measured by the temperature sensor 38 and from the value for the gas volume flow dV / dt measured by the volume flow sensor 40 or alternatively 44.

[0058] For example, if the calorific value sensor 34 measures a value for the Wobbe number WS, the calorific value HS of the gas can be calculated as follows: H S = W S ⋅ ρ T p / ρ 0 T p , where ρ is the gas density of the gas in the gas line and ρ 0 is the gas density of dry air under the same pressure and temperature conditions as in the gas line. The gas density ρ(T, p) is a function of the gas temperature T and the gas pressure p and is determined by the control device as a function of the measured gas temperature and the measured gas pressure. The relationship between gas temperature, gas pressure and gas density ρ(T, p) can be stored, for example, as a formula or as a table in a memory of the control device 32. Likewise, the gas density ρ 0 (T, p) is a function of the gas temperature T and the gas pressure p and can also be stored as a formula or as a table in a memory of the control device 32.

[0059] The calorific value HS of the gas and the volume flow dV / dt can then be used to calculate the combustion power of the gas stream 31.

[0060] The measuring device 22 may further comprise a user interface 46, for example with a screen, via which the calculated calorific value of the gas or the calorific power of the gas stream 31 can be displayed.

[0061] Furthermore, the measuring device 22 can have a data interface 48 for connection to a network 50 in order to be able to transmit, for example, the calorific value or the combustion power of the gas stream 31 to a central server 52, for example for billing purposes.

[0062] The housing 24 can therefore accommodate in particular the control device 32, the sensors 34, 35, 38, 40, the air supply line 37 for the defined air-gas mixture, the measuring chamber 33 with the calorific value sensor 34, in particular a pellistor, or other gas sensors, a gas sensor for measuring the absence of gas in the ambient air, housing ventilation, interfaces for connecting existing sensors for ambient temperature measurement, gas temperature measurement, volume flow measurement, ambient pressure measurement, gas pressure measurement, air humidity measurement, gas humidity measurement or the respective sensors, if they are not present, and a data memory for 5-minute values ​​of all sensors for two years, a power supply, e.g. via a PV module, and a power distribution network, interfaces for reading out data, e.g. with WLAN or Bluetooth standard interfaces or GPRS up to 5G data transmission standard.

[0063] Fig. 3 shows a second exemplary embodiment of the measuring device in a schematic representation. The measuring device 62 is provided on a gas line 66 of a gas distribution network and comprises a control device 64, a calorific value sensor 68, which is arranged in a measuring chamber 69 connected to the gas line 66, and further sensors, namely a pressure sensor 70, a temperature sensor 72, and a volume flow sensor 74. The calorific value sensor 68 can be a pellistor or another gas sensor for detecting gaseous substances, in particular a gas sensor that converts thermal and / or chemical information of the gas to be measured into an electrically usable signal.

[0064] During operation, the control device 64 receives a value for the Wobbe number WS of the gas flow 67 conducted in the gas line 66 from the calorific value sensor 68, a value for the gas pressure p in the gas line 66 from the pressure sensor 70, a value for the gas temperature T of the gas flow 67 in the gas line 66 from the temperature sensor 72 and a value for the volume flow dV / dt of the gas flow 67 flowing through the gas line 66 from the volume flow sensor 74 and calculates therefrom a value for the calorific value HS of the gas flow 67.

[0065] The control device sends information about the calculated calorific value HS , for example its value or information as to whether a predetermined lower limit is undershot or an upper limit is exceeded, via a data interface 76 of the measuring device 62 connected to a network 78 to a server 80, for example a central server 80 of the local gas distribution network, which monitors the gas quality in the local gas distribution network.

[0066] Fig. 4 shows a first embodiment of the gas distribution network in a schematic representation. The gas distribution network 92 comprises a gas pipeline system 94 consisting of interconnected gas pipelines 96, to which various gas consumers 98 (rectangles) and decentralized feed-in systems 100 (triangles) are connected. The gas distribution network 92 is connected at a central feed-in point 102 to a supra-regional gas network 104, from which Fig. 4 a long-distance gas pipeline 106 is shown.

[0067] At the central feed-in point 102, a central measuring device 108 is provided which measures the quality, in particular the calorific value, of the gas fed from the long-distance gas pipeline 106 into the gas distribution network 92.

[0068] In addition, decentralized measuring devices 110 are provided in the area of ​​the decentralized feed-in systems 100, which measure the quality, in particular the calorific value, of the gas fed into the gas distribution network 92 from the decentralized feed-in systems 100.

[0069] The decentralized measuring devices 110 have a structure like the measuring devices 22 or 62 from Fig. 2 and 3 and are therefore significantly more cost-effective and compact than the measuring devices 16 used in the prior art from Fig. 1 . This allows several such measuring devices 22 to be used in the gas distribution network 92 without the gas distribution network 92 becoming uneconomical.

[0070] The central measuring device 108 can be constructed like the central measuring device 16 known from the prior art with a gas chromatograph or a calorimeter or - for further cost savings - also with a measuring device corresponding Fig. 2 or 3 .

[0071] By providing multiple measuring devices 108, 110 in the gas distribution network 92, particularly at the decentralized feed-in systems 100, the quality of the gas in the gas distribution network 92 can be better monitored. In particular, the quality measurements on the gas streams fed in by the decentralized feed-in systems 100 can be used to detect or calculate deviations in the gas quality in specific areas.

[0072] To monitor the gas quality in the individual areas of the gas distribution network 92, the measuring devices 108, 110 are preferably configured to transmit information about the measured calorific values ​​to a central server 112. The gas quality can then be calculated by area based on the transmitted information on the server 112. Furthermore, the server 112 can provide information about the gas quality for billing purposes or trigger the issuance of a warning message in the event of deviations in the gas quality in the gas distribution network 92.

[0073] Monitoring the quality of the gas streams fed in by the decentralized feed-in systems 100 also enables control of the feed-in if the gas quality lies outside a permissible range, namely if it contains too much hydrogen. For this purpose, a decentralized feed-in system 100 can, for example, receive information about the gas quality from the respective measuring device 110 (in Fig. 4 (illustrated by the dashed line between measuring device 110 and decentralized feed-in system 100) and control the feed-in accordingly, possibly even stopping it if the hydrogen content exceeds a specified limit. The decentralized feed-in systems 100 can also be controlled via the central server 112.

[0074] Fig. 5 shows a second embodiment of the gas distribution network in a schematic representation. The gas distribution network 122 has a similar structure to the gas distribution network 92. Corresponding components are provided with the same reference numerals.

[0075] In the gas distribution network 122, instead of the decentralized measuring devices 110 at the decentralized feed-in systems 100, respective decentralized measuring devices 124 (small circuits) are provided at the individual gas consumers 98. However, it is also conceivable that both decentralized measuring devices 110 are provided at the decentralized feed-in systems 100 and decentralized measuring devices 124 are provided at the gas consumers 98.

[0076] The decentralized measuring devices 124 have a structure like the measuring devices 22 or 62 from Fig. 2 and 3 and are therefore significantly more cost-effective and compact than the measuring devices 16 used in the prior art from Fig. 1 . As a result, several such measuring devices 22 can be used in the gas distribution network 92, possibly even at essentially every gas consumer, without the gas distribution network 92 becoming uneconomical.

[0077] Some of the gas consumers 98 may, for example, be households. In this case, the associated decentralized measuring devices 124 may be located near the house connections of these households. Since house connections have volume flow sensors for billing purposes, the decentralized measuring device 124 may, for example, be arranged as shown in Fig. 2 shown can be connected to the existing volume flow sensor via a data interface 42, so that a separate volume flow sensor of the decentralized measuring device 124 is unnecessary and the devices can thus be manufactured even more cost-effectively.

[0078] The decentralized measuring devices 124 located in the area of ​​each gas consumer 98 allow the gas quality, in particular the calorific value, of the gas stream drawn by a gas consumer 98 from the gas distribution network 122 to be directly measured, enabling accurate billing based on the drawn calorific value. For this purpose, the individual decentralized measuring devices 124 can transmit information about the gas quality, for example, to the central server 112.

[0079] Monitoring the quality of the gas streams extracted by the gas consumers 98 also makes it possible to adapt a combustion process at the gas consumer to the gas quality. For this purpose, a gas consumer 98 can, for example, receive information about the gas quality from the respective measuring device 124 (in Fig. 4(illustrated by dashed lines between some measuring devices 124 and the respective gas consumers 98) and control the combustion process accordingly, possibly even stopping it, for example, if the hydrogen content is above a specified limit. The combustion processes at the gas consumers 98 can also be controlled via the central server 112.

Claims

1. Use of a measuring device (22, 62, 108, 110, 124) for determining the calorific value of a gas flow (31, 67) in a gas line (30, 66, 96) of a gas distribution network (92, 122), - wherein the measuring device comprises a calorific value sensor (34, 68) which is configured to measure a value for the gas calorific value of a gas in a gas line (30, 66, 96), and - wherein the measuring device has a control device (32, 64) which is configured to determine a value for the calorific value of the gas flow (31, 67) from the measured value for the gas calorific value and optionally further obtained measured values relating to the gas flow (31, 67), - wherein the gas distribution network (92, 122) comprises a gas line system (94) of interconnected gas lines (30, 66, 96), and - wherein the measuring device (22, 62, 108, 110, 124) is arranged and configured to determine the calorific value of a gas flow (31, 67) through one of the gas lines (30, 66, 96) of the gas line system (94), characterised - in that a decentralised gas feed-in system (100) is connected to a gas line (30, 66, 96) of the gas line system (94), wherein the measuring device (22, 62, 110, 124) is configured to determine the calorific value of the gas flow (31, 67) fed into the gas line system (94) by the decentralised gas feed-in system (100), - in that the control device is configured to determine information about the composition of the gas flow, namely about the hydrogen content, from the determined value for the calorific value, and - in that the decentralised gas feed-in system (100) is configured to control the gas feed into the gas line system (94) as a function of the calorific value of the gas flow determined by the measuring device (22, 62, 110, 124), namely to reduce or stop the gas feed into the gas line system if the hydrogen content determined from the determined value for the calorific value exceeds a predetermined maximum limit.

2. Use according to claim 1, characterised - in that a pellistor or another gas sensor for detecting gaseous substances, in particular a gas sensor which converts thermal and / or chemical information of the gas to be measured into an electrically usable signal, is used as the calorific value sensor (34, 68).

3. Use according to claim 1 or 2, characterised - in that the measuring device (22, 62, 108, 110, 124) is configured to obtain a measured value for the gas pressure in the gas line (30, 66, 96), and - in that the control device (32, 64) is further configured to determine the value for the calorific value of the gas flow (31, 67) as a function of the measured value for the gas pressure.

4. Use according to claim 3, characterised - in that the measuring device (22, 62, 108, 110, 124) has a pressure sensor which is configured to measure a value for the gas pressure in the gas line (30, 66, 96).

5. Use according to one of claims 1 to 4, characterised - in that the measuring device (22, 62, 108, 110, 124) is configured to obtain a measured value for the gas temperature in the gas line (30, 66, 96), and - in that the control device (32, 64) is further configured to determine the value for the calorific value of the gas flow (31, 67) as a function of the measured value for the gas temperature.

6. Use according to claim 5, characterised - in that the measuring device (22, 62, 108, 110, 124) has a temperature sensor (38, 72) which is configured to measure a value for the gas temperature in the gas line (30, 66, 96).

7. Use according to one of claims 1 to 6, characterised - in that the measuring device (22, 62, 108, 110, 124) is configured to obtain a measured value for the gas volume flow in the gas line (30, 66, 96), and - in that the control device (32, 64) is further configured to determine the value for the calorific value of the gas flow (31, 67) as a function of the measured value for the gas volume flow.

8. Use according to claim 7, characterised - in that the measuring device (22, 62, 108, 110, 124) has a volume flow sensor (40, 74) which is configured to measure a value for the gas volume flow in the gas line (30, 66, 96).

9. Use according to claim 8, characterised - in that the measuring device (22, 62, 108, 110, 124) has a data interface (42) for connecting the measuring device (22, 62, 108, 110, 124) to a volume flow sensor (44) of a house service connection, and - in that the control device (32, 64) is configured to receive the measured value for the gas volume flow in the gas line (30, 66, 96) via the data interface (42).

10. Gas distribution network (92, 122), - with a gas pipe system (94) of interconnected gas pipes (30, 66, 96) and - with a measuring device (22, 62, 108, 110, 124) for determining the calorific value of a gas flow (31, 67) in a gas line (30, 66, 96), - wherein the measuring device has a calorific value sensor (34, 68) which is configured to measure a value for the gas calorific value of a gas in a gas line (30, 66, 96), - wherein the measuring device has a control device (32, 64) which is configured to determine a value for the calorific value of the gas flow (31, 67) from the measured value for the gas calorific value and optionally further obtained measured values relating to the gas flow (31, 67), and - wherein the measuring device (22, 62, 108, 110, 124) is arranged and configured to determine the calorific value of a gas flow (31, 67) through one of the gas lines (30, 66, 96) of the gas line system (94), characterised in that - in that a decentralised gas feed-in system (100) is connected to a gas line (30, 66, 96) of the gas line system (94), wherein the measuring device (22, 62, 110, 124) is configured to determine the calorific value of the gas flow (31, 67) fed into the gas line system (94) by the decentralised gas feed-in system (100), - in that the control device is configured to determine information about the composition of the gas flow, namely about the hydrogen content, from the determined value for the calorific value, and - in that the decentralised gas feed-in system (100) is configured to control the gas feed into the gas line system (94) as a function of the calorific value of the gas flow determined by the measuring device (22, 62, 110, 124), namely to reduce or stop the gas feed into the gas line system if the hydrogen content determined from the determined value for the calorific value exceeds a predetermined maximum limit.

11. Gas distribution network according to claim 10, characterised in that a gas recipient (98) is connected to a gas line (30, 66, 96) of the gas line system (94), in particular via a house service connection, wherein the measuring device (22, 62, 110, 124) is configured to determine the calorific value of the gas flow (31, 67) supplied to the gas recipient (98).

12. Gas distribution network according to claim 11, characterised in that the gas recipient (98) is configured to control the gas take from the gas line system (94) or a combustion process operated with the taken gas depending on the calorific value of the gas flow determined by the measuring device (22, 62, 110, 124).