Gas vortex flowmeter

In the field of industrial gas metering,Gas vortex flowmeterWith its precise adaptability to gas media, it has become the core equipment for measuring gas flow rates such as natural gas, compressed air, nitrogen, and coal gas, and is widely used in industries such as energy, petrochemicals, municipal engineering, and metallurgy. It is based on the principle of "Karman vortex street" and integrates specialized designs such as temperature and pressure compensation, explosion-proof, and anti-interference to address the susceptibility of gas density to temperature and pressure. It not only solves the problems of large pressure loss and narrow range in traditional gas flow meters (such as orifice flow meters), but also achieves digital data management through intelligent modules, adapting to the needs of industrial automation and gas trade settlement.

1、 Core advantage: Features specifically designed for gas measurement

1. Strong gas adaptabilityIn response to the characteristics of low gas density and susceptibility to temperature and pressure fluctuations, high-precision temperature and pressure sensors are built-in, supporting real-time temperature and pressure compensation. Density changes are automatically corrected through the ideal gas state equation to ensure measurement accuracy is maintained even in working conditions (such as changes in natural gas transportation pressure and compressed air temperature). The conventional accuracy reaches ± 0.5%~± 1.0% R, meeting the requirements of trade settlement level.

2. Wide range anti-interferenceAt Reynolds numbers ranging from 5 × 10 ³ to 1 × 10⁶Within the range, the vortex frequency is linearly related to the gas flow rate, with a range ratio of 1:10~1:30. It can cover a wide range of measurements from 0.3m/s (low flow rate natural gas) to 30m/s (high flow rate compressed air), and is suitable for intermittent gas supply and scenarios with large load fluctuations (such as factory air compressor start stop, residential gas morning and evening peak). At the same time, dual frequency excitation and digital filtering technology are adopted to effectively resist pipeline vibration and motor electromagnetic interference, ensuring signal stability.

3. Safe, durable, and low maintenanceThere are no mechanical moving parts inside the measuring tube, and measurement is only achieved through vortex generators and piezoelectric/capacitive detectors to avoid wear and jamming caused by gas impurities (such as dust and small particles). The service life is up to 8-10 years. For flammable and explosive gases such as natural gas and coal gas, we provide explosion-proof design (Exd IIB T4) and intrinsic safety design (Exia IIC T6) to meet the safety requirements of hazardous environments. The maintenance volume is only one-third of that of turbine flow meters.

4. Comprehensive intelligent functionsEquipped with LCD/OLED screen, real-time display of instantaneous flow rate, cumulative flow rate, gas temperature, pressure, standard volume flow rate and other parameters; Supports data storage (with a capacity of over 100000 records), and can export historical data through a USB flash drive to meet energy consumption statistics and environmental traceability needs; Equipped with fault self diagnosis function, it can monitor issues such as abnormal vortex signals, sensor failures, and temperature and pressure compensation failures. Through sound and light alarms or fault code prompts, it reduces the difficulty of operation and maintenance.

2、 Working principle: Accurate conversion logic of gas flow rate

Gas vortex flowmeterThe core of the measurement is the three-stage conversion of "gas flow rate vortex frequency standard flow rate", and the key design for enhancing gas characteristics is:

1. Mechanical measuring unitAfter entering the measuring tube, the gas flows through a triangular/trapezoidal vortex generator (mostly made of 316L stainless steel or Hastelloy), and alternately generates vortices on both sides of the generator (Karman vortex street). The higher the gas flow rate, the faster the vortex frequency. The pressure fluctuations caused by the vortex are captured by a high-temperature and corrosion-resistant piezoelectric detector, which outputs an electrical signal proportional to the frequency. The body size is optimized by gas fluid dynamics to ensure stable vortex streets can still be generated at low flow rates, avoiding measurement blind spots caused by low gas flow rates.

2. Intelligent compensation and computing unitThe original electrical signal is amplified, filtered, and then transmitted to the microprocessor according to the formulaInstantaneous volumetric flow rate Q=f × π × D ² × d/(4 × St)(f is the vortex frequency, D is the inner diameter of the tube, d is the size of the generator, and St is a constant value) Calculate the volumetric flow rate under operating conditions; Real time gas temperature and pressure are collected through built-in temperature sensors (accuracy ± 0.5 ℃) and pressure sensors (accuracy ± 0.2% FS), and then input into the ideal gas state equationQn = Q×(P0×T)/(P×T0)(Qn is the standard volumetric flow rate, P0 and T0 are the standard state temperature and pressure, P and T are the operating temperature and pressure), automatically converted to standard volumetric flow rate, eliminating the impact of temperature and pressure fluctuations on measurement, and ensuring that data meets trade settlement or process control requirements.

3、 Classification and selection: Accurate matching of gas working conditions

（1） Mainstream classification

1. According to installation method：

o Pipeline type: directly connected to pipeline flanges/threads, suitable for DN15~DN300 gas pipelines (such as natural gas inlet pipelines, factory compressed air branch pipes), with high measurement accuracy, and is the mainstream type in industry.

o Insertion type: Insert the probe through the pipeline opening without cutting off the pipeline, suitable for large-diameter gas pipelines ranging from DN300 to DN2000 (such as urban natural gas pipeline main pipes and power plant blast furnace gas pipelines), with low installation costs, and can achieve multi-point measurement of average flow velocity with an accuracy of ± 1.5% to ± 2.0% R.

o Clamp on type: Clamp on flange connection, no welding required, suitable for thin-walled gas pipelines (such as laboratory gas pipelines) or temporary measurement scenarios.

2. According to explosion-proof level：

o Ordinary type: suitable for clean gas environments without explosion risk (such as compressed air and nitrogen transportation), without explosion-proof design, and with low cost.

o Explosion proof type: Separated explosion type (Exd IIB T4), suitable for IIB level explosion-proof scenarios such as natural gas and coal gas; Intrinsic safety type (Exia IIC T6), suitable for IIC level high-risk explosion-proof scenarios such as hydrogen and acetylene, with higher safety and meeting the requirements for use in hazardous areas such as chemical and petroleum industries.

3. According to the compensation method：

o Single compensation type: only equipped with pressure compensation or temperature compensation, suitable for gases with small temperature and pressure fluctuations (such as workshop compressed air, temperature fluctuations ≤ 5 ℃).

o Double compensation type: with temperature and pressure compensation at the same time, suitable for gases with large temperature and pressure fluctuations (such as natural gas long-distance pipelines, steam tracing gas pipelines)

（2） Key points of selection

1. Gas characteristic adaptationClarify the type of gas (clean/containing impurities, flammable and explosive) - for gases containing impurities (such as coal gas, dusty nitrogen gas), an anti blocking structure should be selected and a gas filter (accuracy ≤ 1mm) should be matched; Flammable and explosive gases must be selected with corresponding explosion-proof grade models to avoid safety risks.

2. Flow rate and temperature pressure rangeEnsure that the maximum flow rate under operating conditions is ≤ 80% of the instrument's full range, and the minimum flow rate is ≥ 10%, to avoid accuracy degradation caused by range overload or too low; Confirm that the maximum temperature and pressure of the gas do not exceed the rated value of the instrument (conventional models have a temperature resistance of -40~200 ℃ and a pressure resistance of 1.6~10MPa, while high-temperature and high-pressure models can reach 350 ℃ and 32MPa).

3. Functional and authentication requirementsTrade settlement requires the selection of dual compensation models with metrological certification (OIML R60, CNAS) to ensure data legality; The communication protocol (RS485 Modbus, HART, Profinet) needs to be confirmed for automation scenarios to achieve interconnection with PLC/DCS systems; Remote monitoring requirements can choose models with 4G/LoRa wireless modules.

4、 Industry application: Addressing pain points in gas metering

· energy industryDouble compensation explosion-proof pipeline typeGas vortex flowmeter(DN50~DN200) used for natural gas distribution stations to measure natural gas distribution flow rate. Standard volume flow data is transmitted to the gas company dispatch center through 4G, enabling remote meter reading and trade settlement; At shale gas extraction sites, intrinsic safety typeGas vortex flowmeterMeasure the flow rate of associated gas during mining to adapt to high-risk explosion-proof environments.

· petrochemical: Anti blocking plug-in typeGas vortex flowmeter(DN800) is used for refining plant blast furnace gas pipelines, equipped with filters to reduce the impact of dust in the gas on instruments, monitor gas flow in real time, and optimize combustion processes; Corrosion resistance in ethylene plantsGas vortex flowmeterMeasurement of cracking gas flow rate using Hastelloy alloy material, suitable for corrosive gas conditions.

· Municipal industry: Pipeline typeGas vortex flowmeter(DN25~DN100) used for natural gas pressure regulating stations in residential areas, with dual compensation function to ensure accurate gas metering for residents, supporting RS485 communication for centralized meter reading, replacing manual meter reading; In urban gas emergency reserve stations, explosion-proof typeGas vortex flowmeterMonitor gas reserves and delivery flow to ensure stable gas supply.

· Metallurgical industry: High temperatureGas vortex flowmeter(Temperature resistant to 350 ℃) used in the converter gas pipeline of steel plants to measure the gas recovery flow rate, transmit the data to the energy management system, and achieve efficient utilization of gas resources; In the aluminum factory, ordinary typeGas vortex flowmeterMeasure the flow rate of nitrogen protective gas to ensure a stable inert gas environment during aluminum processing.

5、 Maintenance points: Ensure stable gas measurement

1. Regular cleaning and inspectionCheck the filter every 3-6 months to remove impurities from the filter element and avoid blockages that may affect gas circulation; Disassemble the sensor every 6-12 months, clean the vortex generator and detector, remove dust or oil stains, and ensure stable vortex generation; Check if the wiring terminals are loose to avoid signal interruption caused by poor contact.

2. Environment and Safety ProtectionInstruments installed outdoors need to be equipped with rain and sun protection covers to prevent rainwater from entering the converter or high temperature exposure from affecting the lifespan of electronic components; Explosion proof instruments are strictly prohibited from being disassembled while powered on. During maintenance, the power supply must be cut off first to ensure compliance with explosion-proof safety regulations; Stay away from strong magnetic fields (such as high-voltage cables and large motors) to reduce the impact of electromagnetic interference on signals.

3. periodic calibrationCalibration of instruments should be carried out every 1-2 years, and trade settlement instruments must be calibrated annually. Standard meter method or sonic nozzle method can be used to calibrate the linear relationship between vortex frequency and flow rate, temperature and pressure compensation accuracy, ensuring that measurement errors are within the allowable range and avoiding measurement disputes or process control deviations caused by instrument drift.

In conclusion,Gas vortex flowmeterWith the characteristics of "precise compensation, wide range, high safety, and easy maintenance", it has become the preferred equipment in the field of gas metering. With the advancement of industrial gas energy and precision applications, it will further integrate AI intelligent diagnosis and 5G wireless interconnection technology to provide more efficient and reliable metering solutions for gas energy management and trade settlement, helping enterprises reduce costs, increase efficiency, and operate safely.