The Challenge
Electric Arc Furnace (EAF) steelmaking presents particularly demanding conditions for continuous gas flow measurement. Extremely high temperatures, heavy particulate loading and turbulent exhaust gases can make many conventional flow measurement technologies unsuitable.
CODEL was approached to provide flow monitoring solutions for two EAF steel mills in the United States, each presenting a different measurement challenge.
At a steel plant in the Midwest United States, flow measurement was required on two EAF ducts before they combined into a common stack. Exhaust temperatures ranged from approximately 300°F to 700°F (149°C to 371°C) with a high particulate loading.
As the measurement formed part of the plant’s Continuous Emissions Monitoring System (CEMS), the solution also needed to be suitable for certification to applicable US EPA 40 CFR Part 75 requirements.
At a second steel mill in the Southwest United States, the challenge was even more demanding. The plant required flow measurement directly within the hot gas offtake from an electric arc furnace, where exhaust temperatures exceeded 1,000°F (538°C) and the gas stream contained extremely high levels of dust.
Why Conventional Flow Measurement Wasn't Suitable
The combination of temperature and particulate loading created significant limitations for other commonly used flow measurement technologies.
In these conditions, an S-type Pitot tube could be susceptible to blockage from the high dust loading, while an ultrasonic flow monitor could struggle to maintain a reliable signal through the heavily dust-laden gas.
Both plants therefore required a measurement technology capable of operating reliably without introducing sensitive components directly into the harsh exhaust gas stream.
The CODEL Solution
Both applications were addressed using the CODEL VCEM 5100 Continuous Flow Monitoring System.
Rather than relying on intrusive components within the gas stream, the VCEM 5100 uses two infrared detectors mounted externally on the duct, typically positioned approximately one metre apart in the direction of flow.
The system measures the naturally occurring infrared emissions produced by the turbulent gas stream. Cross-correlation analysis determines the time taken for these naturally occurring patterns to travel between the two measurement points, allowing gas velocity to be calculated continuously.
This approach makes the VCEM 5100 particularly suited to applications involving high temperatures, high particulate concentrations and challenging process conditions.
Designed for Demanding EAF Applications
With the measurement equipment mounted externally to the duct, the VCEM 5100 can operate at exhaust gas temperatures in excess of 1,000°C (1,832°F).
High particulate loading is also well suited to the measurement principle, as the system uses naturally occurring infrared variations within the moving gas stream to determine velocity.
High-efficiency air curtains help protect the optical windows from contamination, extending maintenance intervals and reducing the need for routine cleaning.
For applications requiring mass emissions reporting, measured gas velocity can also be combined with duct area and pollutant concentration to calculate total mass flow.
The Result
The VCEM 5100 provided both US steel mills with a continuous flow measurement solution capable of operating in conditions where alternative technologies faced significant limitations.
For the Midwest installation, the system enabled flow measurement on the individual EAF ducts before they combined into the common stack, supporting the plant’s CEMS requirements.
At the Southwest installation, the VCEM 5100 provided continuous measurement directly within an exhaust stream exceeding 1,000°F, despite the extremely high particulate loading.
The two installations demonstrate how the VCEM 5100 can provide reliable continuous flow measurement in some of the most demanding gas conditions encountered within the steel industry.
The VCEM 5000/5100 represents the latest generation of CODEL’s unique flow monitors. These systems measure the velocity of stack gases using a highly accurate time of flight measurement that is derived from a cross correlation analysis of the infra-red emissions of the turbulent gas.
The EnergyTech 600 is CODEL’s dependable triboelectric dust monitor, built for continuous, real-time measurement of particulate emissions in industrial environments. It delivers accurate dust level readings to support compliance and improve operational efficiency.
