A Revolution in BTU Calculation

The Heating Value (often referred to as BTU or CV) calculation used in operating flare stacks, waste gas boilers and fired heaters is an application where the new SERVOTOUGH SpectraScan from Servomex (UK) significantly challenges traditionally slower and more expensive methods of gas analysis.

While waste and recycled gases are a valuable energy source in the fuelling of combustion processes such as fired heaters or steam boilers, the variability of these gases can make their use unpredictable and difficult to control. Traditional Heating Value analysis techniques are prone to errors in real operation, as they rely on combusting a known volume flow rate of the fuel with a known volume flow rate of air, followed by a measurement of heat: either the exhaust gases or the flame. While the technique is viable, the variables in each part of the analysis compound errors.

In contrast, the innovative “Tunable Filter Spectroscopy” (TFS) utilised by the SpectraScan provides an instant measurement and avoids the error compounding of other techniques. TFS works by taking advantage of the measurement properties produced by the absorption of infrared light as it passes through a volume of gas. The absorption spectrum of each compound is unique, it acts as a “fingerprint” for identification or speciation analysis, while the magnitude of the absorption is a function of the number of molecules of the gas, according to Beer-Lambert law. With a known path length, pressure and temperature, the magnitude of the absorption spectra can be used to compute volumetric concentrations, giving near-instant measurement results.

This enables the SpectraScan to offer precise and simple optimisation of on-site gases for all Heating Value or Wobbe Index pplications. By replacing the need for complex, high maintenance and potentially error-prone instruments with the reliable, low-maintenance technology of the SpectraScan, the efficiency of the process is greatly improved and overall cost of ownership significantly reduced.