FCI Flow Meter Installed on Gas Digester Pipe Click here to enlarge imageIn addition to the digester gas bag, the system also includes an array of piping and processes for gas distribution and disposition. Thermal mass flow meters calibrated for digester gases are also well suited for these applications. Flare gas stacks typically require a flow meter to measure and report the quantity of gases burned off and as feedback for the digester’s process control. In the co-generation system, gas flow meters are installed at the engine’s fuel feed lines, both in digester gas lines and supplemental natural gas lines that ensure engine operation and BTU performance.
In planning the installation of the digester system’s new flow meters, the piping layout was found to be less than optimal for accurate measurement. Nearly all flow meter technologies require a straight pipe run of 0-10 diameters upstream and 0-5 diameters downstream, or more. In this case, there were problematic elbows too close to the meter. The team saved re-piping costs by installing a tab-type Vortab meter run flow conditioner. The conditioner eliminated any undesirable line conditions, such as swirl, and ensured a fully developed flow profile for accurate measurement in only nine diameters total.
Results
The digester gas system now operates more effectively and efficiently. The utility is able to achieve improved digester process control, ensure compliance with local environmental regulations and optimize the operation of its co-gen engine system. Their maintenance expenses also were dramatically reduced, with the thermal mass flow meter requiring virtually no attention because of its no-moving parts, non-fouling design.
About the Author:
Steven Craig is a Senior Member of the Technical Staff at Fluid Components International (FCI). He has a Bachelor of Science degree from Iowa State University and 20 years of instrumentation experience, 10 years in aerospace and 10 years with FCI. He works in the FCI Beijing, China, office.