Biogas from digesters is typically 60–70% methane and 30–40% carbon dioxide. Biogases fuel engine-generators or gas turbines to produce electricity. They also fuel boilers to produce heat or steam. Biogas utilization has increased in industrial processing, wastewater treatment plants, municipal landfills, and livestock farms.
Biogas level and flow applications
- BIOGAS FLOW: In all forms of biogas production, safe and reliable gas flow measurement is essential in the collection, disposal or re-use of biogas. Thermal mass flow meters are widely used in landfill, anaerobic digestion and gasification processes. A flow meter measuring biogas must provide low flow sensitivity, low pressure drop, and tolerate temperature and pressure changes.
- SCRUBBER VESSEL: Essential in gasification processes, scrubbers remove odors, pollutants, acid gases and chemical wastes from biogas. Accurate level monitoring of the scrubbing water necessitates a control to automatically feed the correct amount of make-up water to the recycle reservoir either continuously or on a periodic basis. The level monitoring device for water-out control should be equipped with a level alarm.
- BIOGAS DEHYDRATION: As biogas emerges from a digester or a landfill it is saturated with water that causes corrosion problems upon condensation. Dehydration systems using air, vacuum and desiccant processes to remove water typically include a holding tank for water drawn off the gas with a level control actuating a valve to vacate the tank at high level. Biogas is dehydrated according to the customer’s specifications for maximum water content. Some uses, such as boiler fuel, require an extremely dry gas.