- Monitor siloxane before gas engine to ensure that it is completely removed
- Measure Methane (CH4) and Carbon dioxide (CO2) at the same time as quality control of gas engine fuel
Siloxanes are a relatively new impurity found in biogas, as their use within household products has gradually increased over the last fewdecades. They are now commonly added to products such as cleaning agents, deodorants and cosmetics to improve their consistencyand performance. These products are now typically used for biogas production. Due to their volatility, the siloxanes become entrained with the biogas during the digestion stage, and must be removed to below a threshold level before the biogas can be safely used to produce energy. This ‘total silicon’ limit level varies by application, and the limit values themselves are still under scrutiny at European standardisation level.
Raw biogas from the digester is upgraded using a series of activated carbon beds before it is fed to gas turbines. The beds undergo anine-hour regeneration cycle, in which a bed is taken off line after six hours for cleaning. The biogas flow is diverted onto a clean bedwhilst the previous bed regenerates to ensure there is no interruption to the process.