As an important industrial energy source, measuring steam flow is key to how well and how cheaply industrial production can be done.
However, traditional methods of measuring steam flow, such as orifice plates and nozzle flowmeters, often have issues such as inaccuracy and excessive maintenance requirements. On the other hand, vortex flowmeters are very good at measuring steam. This is because they have a special way of measuring and advanced technology. This establishes them as a key component of modern steam measurement technology.
Operating Principle of Vortex Flow Meters:
The operational principle of vortex steam flow meters is based on the Karman vortex street effect. When steam flows past non-streamlined vortex generators (such as triangular or trapezoidal columns) within a pipeline, regular vortices are generated alternately on both sides.
These swirling masses of air form two rows of swirling air that rotate in opposite directions. The more quickly the steam is moving, the more often these lumps of ice form and break up. The steam flow rate can be calculated by detecting this frequency.
To work out the flow rate (Q), we need to use this formula: Q = A · v = f · d · A / St, where A is the cross-sectional area of the pipe, v is the flow velocity, f is the vortex frequency, d is the characteristic width of the generator and St is the Strouhal number, which is related to the shape of the vortex generator and is typically constant.
To calculate the mass flow rate, you need to consider the steam density. This must be corrected for temperature and pressure.
Steam
Steam is the gaseous form assumed by a substance when heated and pressurised, transforming from liquid to vapour. In layman’s terms, vapour is the gas produced when a liquid (liquid substance) evaporates or boils.
Steam is ubiquitous in daily life. With the rapid advancement of thermal power and electricity industries, coupled with heightened corporate scrutiny of energy costs, steam metering has gained increasing prominence.
Types of Steam
Saturated Steam:
The most common type used in industrial heating and light manufacturing. Due to its one-to-one correspondence between temperature and pressure, it is prone to condensation and liquid carryover as a result of operational fluctuations.
Measurement requires integrated temperature-pressure compensation. To prevent condensate impacting the sensor and causing measurement signal fluctuations or component damage, vortex generators with anti-liquid-strike structures should be prioritised.
Condensate management must be implemented during on-site installation.
Superheated Steam:
It’s mostly used in power generation and high-temperature chemical processes. The most important thing to know about it is that there isn’t a fixed temperature-pressure relationship.
They usually have higher operating temperatures and pressures, so you don’t have to worry about condensation or liquid carryover. You also need to make sure you use integrated temperature-pressure compensation for measurement.
If you’re dealing with high-temperature superheated steam (≥250°C), you’ll need to use high-temperature-resistant vortex flowmeters. It’s best to set up the converter away from the high-temperature measuring tube to stop it from overheating and messing up the rest of the instrument.
Advantages of Vortex Flow Meters in Steam Measurement:
High-Precision Measurement:
The measurements are spot on, and the repeatability of the data is great, too. The usual accuracy you can get with this kind of measurement is between plus or minus one to two per cent.
Measurement data stability significantly surpasses that of traditional flow meters. This characteristic precisely meets the process control and energy metering requirements of steam systems, making it particularly suitable for industrial production processes demanding high-precision flow data.
High Operational Reliability:
Its streamlined structural design with minimal internal core components fundamentally reduces the probability of equipment failure.
Its robust construction from high-quality, heat- and corrosion-resistant materials enables it to withstand harsh industrial steam measurement conditions, such as high temperatures and pressures, and exposure to corrosive media.
This ensures long-term stable continuous operation, significantly reducing equipment downtime due to faults and minimising losses from production interruptions.
Exceptional Adaptability:
Fully accommodates diverse steam measurement requirements across industrial settings, precisely handling flow measurement scenarios for saturated and superheated steam at varying pressures and temperatures.
Supports multi-range flow measurement capabilities. Manufacturers offer multiple product specifications, enabling flexible selection based on actual steam parameters and process demands to meet varied steam application needs.
Dedicated Temperature Compensation Advantage:
It’s designed to deal with the fact that steam can expand and contract, and it’s got this special module that adjusts the temperature and these sensing parts that can handle high temperatures.
This captures real-time changes in the operating temperature of the steam, automatically performing density correction and flow conversion. This eliminates measurement distortion caused by temperature fluctuations, significantly improving measurement stability.
No additional independent compensation equipment is required, enabling direct adaptation to both saturated and superheated steam conditions.
Non-contact Measurement Design:
The instrument’s core measurement sensor avoids direct contact with the steam medium, effectively preventing erosion, corrosion, and wear from high-temperature steam. This significantly extends the service life of critical components.
The non-contact measurement method also ensures long-term signal stability, maintaining precise measurement accuracy even during prolonged continuous operation without frequent sensor replacement.
Extensive Turndown Ratio Coverage:
It has an exceptionally wide measurement range, typically reaching 1:10 and up to 1:20 in certain models, making it perfect for industrial steam flow measurement in situations where there are significant fluctuations and load imbalances.
You can get precise measurements even when there is not much water flowing through, so you don’t need to replace instruments often because of changing steam flow rates. This makes it much more useful in different situations.
Streamlined Installation:
This meter is much easier to install than traditional differential pressure flowmeters. There is no need for extra parts or piping, so it is quick and easy to install. This reduces the likelihood of things going wrong.
This makes the installation process much quicker. The instrument’s structural design also makes it easy to maintain in the future, as it can be easily disassembled, assembled and calibrated. Routine inspections and fixing any problems can be done quickly, which makes maintenance easier later on.
Multi-format signal output:
Equipped with a comprehensive and flexible array of signal outputs, including pulse output, current output, voltage output, 4-20mA standard analogue output, and RS485 digital communication output.
This allows flexible selection based on the interface requirements of industrial control systems and data acquisition equipment, enabling seamless integration with industrial control systems such as DCS and PLC.
It meets a variety of on-site requirements for data transmission, remote monitoring and system interconnection.
Multi-specification structural customisation:
It offers comprehensive structural and functional customisation solutions that can be tailored to meet a variety of industrial installation and operational requirements. Structural configurations include integrated, split, and insertion types to accommodate varying installation spaces and site conditions.
Connection methods encompass flange clamp (wafer-type), flange connection, threaded connection, and clamp connection to suit different pipe diameters and installation specifications.
Compensation options include temperature-pressure compensation, single-temperature compensation, single-pressure compensation, or no compensation, precisely addressing metering compensation requirements.
Specialised variants such as high-temperature resistant, high-pressure resistant, and explosion-proof models can be customised for demanding steam measurement environments involving extreme temperatures, pressures, or flammable/explosive conditions, comprehensively meeting diverse industrial customisation needs.
Applications of Vortex Flow Meters in Diverse Steam-Related Fields
Municipal heating systems, boiler rooms, and heat exchange stations: Measure saturated/superheated steam for trade settlement, energy consumption statistics, and pipeline network dispatch; combined with temperature and pressure compensation to calculate mass flow.
Power plants and on-site power generation facilities: Monitor steam flow in boilers and steam turbines for heat balance calculations, combustion condition adjustments, and energy-saving analysis.
Chemical and Petrochemical Industries: Measure steam used for process tracing, distillation, and heat exchange to support process control and material balance; 316L material is selected for corrosive environments.
Textile, Paper, Building Materials, and Rubber Industries: Monitor steam consumption in dryers, drying cylinders, and vulcanizing kilns to calculate energy consumption per unit, supporting process stability and energy-saving retrofits.
Food and Pharmaceuticals: Monitors clean steam and sterilization steam to meet GMP requirements and ensure the stability of sterilization processes.
Hotels, Hospitals, and Commercial Complexes: Provides separate metering for heating and sterilization steam to enable precise energy management.
Pipeline Instrumentation Trace Heating: Monitors low-flow trace heating steam to detect leaks and reduce energy waste.
Industrial Energy Systems: Transmits data via 4–20 mA and HART signals to energy management platforms, automatically calculates cumulative flow and carbon emissions, and adapts to fluctuating load conditions.
Common Steam Flow Meters
Vortex Flow Meter: A commonly used meter for steam; features no moving parts, low pressure loss, and temperature/pressure compensation; however, it is susceptible to pipeline vibrations.
Orifice Plate Flow Meters: A classic differential pressure design suitable for thermal settlement in power plants; features high pressure drop, narrow measurement range, and is prone to wear.
Annubar Flow Meter: Insertion-type with low pressure loss; suitable for large pipes, though accuracy at low flow rates is generally limited.
Nozzle/Venturi: Resistant to erosion, high temperatures, and high pressure; commonly used for main steam in power plants; relatively high cost.
Ultrasonic Steam Flow Meter: No pressure loss; supports clamp-on installation; requires high steam dryness.
Coriolis mass flowmeter: Directly measures mass flow; high accuracy; expensive.
Selection Guide
1. Confirm steam type: Distinguish between saturated steam and superheated steam; saturated steam generally requires temperature and pressure compensation.
2. Verify operating parameters: Determine temperature, pressure, typical flow rate, and minimum/maximum flow rates to ensure they fall within the instrument’s measurement range.
3. Pipe Diameter and Installation Space: Prioritize vortex flow meters for small pipe diameters; for large-diameter main lines, consider Annubar or clamp-on ultrasonic meters.
4. Vibration and Noise Environment: Avoid standard vortex flow meters on highly vibrating pipelines; prioritize differential pressure flow meters.
5. Accuracy and Application: Select standard vortex flow meters for internal energy consumption tracking; choose models with higher accuracy grades for trade settlement.
6. Medium Cleanliness: For steam containing impurities or subject to severe scouring, prioritize orifice plates or Venturi meters to reduce wear.
7. Cost and Maintenance Budget: For limited budgets, select orifice plates or vortex flow meters; for high-accuracy requirements, select Coriolis mass flow meters.
8. Signal Interface Requirements: If remote transmission to the energy management system is required, confirm support for the 4–20 mA or HART protocol.
Sion-Inst is a company that specialises in making flowmeters and sensors. They have a lot of experience in this area, and they have been doing this job for many years. We use technology and what our customers need to help us make a wide range of vortex, electromagnetic and turbine flow meters, as well as sensor equipment that is used in many different industries. Our solutions are ideal for measuring all types of media, including steam, gases and liquids. They can withstand tough conditions such as high temperatures, pressures and vibrations, while striking a balance between accuracy and durability.
Whether you require flow meter selection for specific operating conditions, high-performance sensor replacements, or bespoke metrology and sensing solutions, we welcome your enquiries at any time. With a sincere approach to collaboration, cost-effective products, and comprehensive technical support, we empower your enterprise to achieve precise, efficient, and intelligent upgrades in metrology and sensing. Together, we shall deepen our engagement in the industrial sector, jointly promoting lean operations and securing mutual long-term growth!
