Critical safety equipment in biogas plants

A biogas plant works with a mixture of methane (50-65%), carbon dioxide and traces of hydrogen sulfide, under very low pressure conditions and with large volumes of stored gas. That combination —flammable gas, permanent explosive atmosphere, low-pressure equipment— makes safety more demanding, not less, than in a conventional petrochemical plant.

Specific risks of biogas

• Permanent explosive atmosphere at the digester head (zone 0/zone 1 according to ATEX).
• Operating pressure of just a few mbar: any vent obstruction can collapse the digester membrane.
• H2S corrosion in the presence of moisture —especially aggressive on carbon steel and brass—.
• Possibility of flame flashback from the flare or the cogeneration engine.
• Foam formation and line clogging in poorly fed digesters.

Critical equipment

Detonation flame arresters + endurance burning

Every connection between the digester and any equipment with a potential ignition source (CHP engine, flare, boiler) requires a detonation-type flame arrester with an endurance burning certificate. The German TRBS 3146/TRBS 3151 standard —the de facto reference in Europe— is explicit on this point.

Pressure-vacuum safety valves for biogas

PV valves for biogas are specific: they must be tight against H2S, use corrosion-resistant materials (AISI 316L as a minimum) and operate at set points of just a few mbar. A standard petrochemical PV valve is not suitable.

Emergency flare

Essential for handling production surpluses when the engine is shut down. It must be sized for the digester's maximum flow rate and feature an automatic pilot and flame monitoring.

Desulfurization system

Reducing H2S from levels of 1,000-3,000 ppm down to <100 ppm dramatically extends the life of the cogeneration engine and lowers corrosion across the entire system.

Foam retention system

An organic overload can generate foam that carries liquid into the gas line. Cyclonic separators and foam breakers prevent damage to compressors and flares.

Regulatory compliance

• ATEX Directive 2014/34/EU for all equipment in classified zones.
• EN 1825-1 / EN 16726 for grid-injection gas quality.
• EN 16723-1 for biomethane injection into transport grids.
• Regulation (EU) 2016/426 for appliances burning gaseous fuels.

Biogas plants that combine mechanical safety with digital monitoring reduce their incident rate by more than 70% compared to plants with minimal passive protection.

Conclusion

The safety of a biogas plant is not solved by adding more equipment, but by using the right equipment, certified specifically for biogas. Tecnovent offers integrated solutions: flame arresters, PV valves, flares and inerting systems designed for the real-world conditions of biogas.