Biogas Measurement from Wastewater to Power Plant
Summary
A Stockholm-based water treatment company generates biogas from its wastewater facility and supplies it to Scandinavian Biogas for energy production. To accurately bill the energy company for the gas delivered, the water company’s project contractor needed a metering solution engineered specifically for this low-pressure, ambient-temperature biogas application.
Application
Biogas from the digester is a mixture of methane and carbon dioxide and is handled at very low pressure and ambient temperature.
| Biogas | CH₄ 58% to 70% + CO₂: 42% to 30%, traces of N₂ and H₂S < 500ppm |
| Flowrate | 400 to 5,000 Nm³/h |
| Pressure | from 15 mbarg to 30 mbarg (0.22 psig to 0.44 psig) |
| Temperature | 0°C to 37°C (32°F to 99°F) |
| Pipe | DN300 (12″) PN10 EN 1.4404 (SS316) |
Benefits:
- Accurate and reliable measurement
- Ability to measure at very low pressure
- Absence of pressure drop
Challenge
Due to the technical challenges ultrasonic technology was selected. To get accurate readings they needed to find a compromise between meter velocity and pressure drop. Our partner’s technical advice was taken into consideration and they went for a DN300 line (12″).
Solution
We supplied our gas flow meter with our T5 transducers mounted on a flowcell with air calibration. That’s a set up that has good records for low pressure application like what we see on flare lines. With this in place, Stockholm water company can now bill accurately Scandinavian Biogas Company and maximize the energy transfer thanks to the absence of pressure drop.
Source: Panametrics Application Note (panametrics.com) — © Panametrics LLC. Localized and adapted by INTECH CONTROL, official Panametrics representative in the Slovak Republic and Hungary.