Smart ultrasonic gas meter with a mechanism for detecting and measuring the combination of natural gas and hydrogen

Abstract

The technical background of this invention is precision instrumentation and fluid metering in smart gas distribution networks with the ability to inject hydrogen (Blended Gas). The technical problem with existing meters is the inability to detect severe thermodynamic changes (such as changes in sound speed and energy density) caused by adding hydrogen to natural gas, which leads to a gross error in calculating standard volume and energy. This invention is a smart ultrasonic gas meter that overcomes the limitations of off-the-shelf chips by utilizing a discrete and reconfigurable analog front-end (AFE) circuit consisting of a network of semiconductor switches and 500 kHz transducers. The operating mechanism is based on the "acoustic spectroscopy" technique; in such a way that the central processor (microcontroller with DSP core) estimates the percentage of hydrogen composition by simultaneously analyzing the "Time-of-Flight" and "Signal Attenuation" in the received signals. The device then corrects the gas compressibility coefficient (Z-Factor) based on the identified composition in real-time using embedded algorithms and calculates the exact volumetric flow. This solution overcomes the challenge of accurate measurement in variable gas mixtures without the need for expensive chromatography analyzers.

Description

Description of the invention Title of the invention Smart ultrasonic gas meter with a mechanism for detecting and measuring the combination of natural gas and hydrogen Technical background of the relevant invention This invention is applicable in the field of precision instrument engineering, flow metering systems, and specifically smart gas meters compatible with blended gas in energy distribution networks. Technical problem and stating the objectives of the invention With the global approach towards clean energy, the injection of hydrogen into natural gas networks (H2NG) is expanding. The technical problem is that hydrogen has very different thermodynamic properties (density, speed of sound, and calorific value) than methane. Current meters (diaphragm or even conventional ultrasonic) have adjusted their calculation formulas based on "pure natural gas". The change in the speed of sound in the hydrogen mixture (which is much faster) and the change in the compressibility factor (Z-Factor) cause a significant error in the calculation of the standard volume of gas. The aim of this invention is to provide a hardware and software solution for real-time detection of the percentage of hydrogen without the need for expensive gas-chromatography devices. A description of the state of the prior art and the history of developments related to the claimed invention. In the prior art, accurate measurement of gas mixtures uses chromatographic analyzers or thermal mass sensors, which are very expensive and energy-intensive and not economically feasible to install in every household. Also, existing ultrasonic meters typically use integrated time-to-digital converter chips (such as the TDC series) that only provide "time of flight" and do not provide access to the raw waveform for more complex analysis (such as signal attenuation), so they are unable to accurately distinguish changes in gas composition. Providing a solution to an existing technical problem along with an accurate, sufficient, and integrated description of the invention This invention solves the challenge of accurate measurement in mixed gas environments by designing a hybrid hardware architecture and corresponding processing algorithm. As shown in Figures 1 and 2, the device includes a central processing unit [3], a discrete analog interface circuit, and a pair of ultrasonic sensors. The main innovation lies in the design of the interface circuit (detailed schematic in Figure 2). Unlike conventional approaches that use integrated time-to-digital converter (TDC) chips with low flexibility, this design uses a reconfigurable analog switching network [1]. This network consists of fast semiconductor switches that are directly controlled by the processor. This structure allows the device to change the receiver circuit and transistor amplifier stage [2] when a change in the speed of sound (indicating hydrogen injection) is detected. This involves adjusting the gain and changing the feedback path to prevent saturation or excessive attenuation of the signal in low-density gaseous environments (such as hydrogen). The system works as follows: 1. The central processor [3] sends a 500 kHz excitation pulse. 2. The received signal passes through the sensors and is conditioned by the switching network [1] and the amplifier [2]. 3. The processor samples the complete analog waveform and simultaneously extracts the "accurate time of flight" and the "amplitude decay rate". 4. Using these two parameters, the percentage of hydrogen composition is extracted from the internal calibration tables and the compressibility coefficient (Z) is corrected in the flow calculation formula. Explanation of shapes, maps and diagrams Figure 1: Overall system block diagram. Figure 2: Analog interface circuit schematic. Figure 3: Algorithm diagram (flowchart). Explanation of the diagram numbering: Number [1]: Analog Front-End switching network. Number [2]: Amplifier transistor driver. Number [3]: Central Processing Unit (MCU). Number [4]: ​​Ultrasonic sensors. Number [5]: Signal input / output to the processor. A clear and precise statement of the advantages of the claimed invention over prior inventions. 1. Ability to detect the percentage of hydrogen composition without the need for an additional chemical sensor (cost reduction). 2. High accuracy at low flow rates due to the use of a 500 kHz frequency. 3. Automatic correction of the standard volume based on changes in the nature of the gas (Adaptive Metering). 4. Hardware flexibility due to the use of a controllable discrete circuit instead of closed ASIC chips. Description of at least one implementation method for implementing the invention In a preferred embodiment, the device operates in a repetitive measurement cycle as follows: 1. Excitation and impedance matching stage: At the beginning of the cycle, the central processing unit generates a pulse train (Burst) with a frequency of 500 kHz and applies it to the transmitter sensor through the driver stage. At the same time, the processor activates the electronic switches in the analog interface circuit (as shown in Figure 2), setting the feedback path and the amplifier gain to a default value. 2. Adaptive Reception Stage: The audio signal is received by the receiver sensor after passing through the fluid. The processing unit first checks the amplitude level of the received signal. If the signal amplitude is weaker or stronger than expected due to the presence of hydrogen (which has a different sound absorption coefficient), the processor immediately changes the arrangement of the intermediate circuit switches to correct the circuit gain without saturating or losing the signal. This "hardware automatic gain control loop" is a major innovation in ensuring signal quality in variable gas mixtures. 3. Signal Processing and Parameter Extraction: The optimized analog signal is sampled by the processor's internal analog-to-digital converter (ADC). The processor, by implementing digital signal processing (DSP) algorithms, extracts two key parameters: a) Accurate Time-of-Flight with nanosecond resolution to calculate the speed of sound in the mixture. b) Signal Attenuation relative to the transmitted pulse. 4. Determine the composition and correct the flow: Using the temperature and pressure data (read from the environmental sensors) and the inputs from the previous step (sound speed and attenuation), the processor refers to a "multi-dimensional look-up table" stored in the device's memory. The output of this table is an estimate of the percentage of hydrogen in the gas mixture. Then, using this percentage, the processor calculates the new gas compressibility factor (Z-Factor) according to the AGA8 standard and corrects the measured gas flow volume. Finally, the corrected flow value is displayed on the device's display or stored. Explicit mention of the industrial application of the invention This invention has direct application in the gas and petrochemical industry, urban gas distribution companies (for hydrogen injection projects into the network), and gas pressure reduction stations (CGS / TBS).

Claims

Complaint What is claimed: 1- An ultrasonic smart gas meter with a mechanism for detecting and measuring the mixture of natural gas and hydrogen, including a gas flow passage pipe, ultrasonic transmitter and receiver transducers, and an electronic signal processing unit; characterized in that: the aforementioned electronic signal processing unit is configured and programmed in such a way that it simultaneously applies the processes of "waveform analysis", "measurement of acoustic energy absorption behavior" and "acoustic spectroscopy" to the acoustic signals received from the transducers; so that from the integration and correlated processing of these three parameters as complementary variables, the concentration and percentage of hydrogen gas in the natural gas mixture are estimated, leading to the creation of a technical effect in compensating for the flow measurement error.

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