Biogas measurement solved with t-mass

Anaerobic digestion continues to form an important element of the Government’s renewable energy drive, as highlighted by the recent ‘Anaerobic Digestion Strategy and Action Plan’ released by DEFRA. Ensuring the right measurement instrumentation is included in the system is key to ensuring the most efficient energy production, and speeding up that vital return on investment.

It is the bi-product from anaerobic digestion, biogas, which is used to produce energy, either via a Combined Heat and Power (CHP) system, or by conversion into biomethane. Either way, the measurement of biogas, both in terms of quality and quantity, is critical to the overall process. These measurements can also be utilised as an indicator of the health of the digester itself.

In terms of flow measurement, biogas is an extremely difficult gas to measure due to several factors. These include the low pressures involved, the moisture content, the variable gas composition and the particulate matter that can be present. A number of flow measurement methods can be implemented for biogas, all of which present their own problems and compromises. However, in terms of possible accuracy and long term stability, one stands out against the rest, namely thermal mass flow measurement.

Endress+Hauser’s thermal mass flowmeter, t-mass, has been successfully proven in many challenging applications. The most predominant of these is biogas measurement. Having been used for many years to measure biogas from sludge digesters in the wastewater industry, t-mass is now being used within anaerobic digester systems in the growing renewable energy market, based on feed stocks such as food waste, agricultural waste and fuel crops.

Available as an in-line or insertion device, t-mass can be built into the design of a new system or retrofitted into existing pipework. And, providing that a few simple rules are followed, a reliable measurement will be obtained.

To support the installation of t-mass, Endress+Hauser has developed a hot tap methodology which allows the device to be installed into an existing system without interrupting the process. An in-situ verification method has also been developed to ensure the measurement system is optimised to the installation.