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Biogas Production: the 4 safety products every Anaerobic Digester should have

The increasing demand for renewable energy has intensified the need for products to protect people, process equipment and the environment. Elmac recognises this need and has developed a market-leading range of safety products to protect commercial, industrial and on-farm Anaerobic Digestion Plants.

Elmac recommends the products below across all Anaerobic Digestion Plants.

1. The Cowhorn Arrangement

The Elmac Technologies® Cowhorn Arrangement attaches pairs of Flame Arresters and Pressure/Vacuum Relief Valves to a 3-way valve, allowing the operator to switch between sets when operational or maintenance needs require. The practical duty/standby arrangement allows continuous operation with zero downtime and minimum disruption to Anaerobic Digestion.

Elmac’s patent-protected Flame Arresters protect Anaerobic Digesters against fire and explosion whilst allowing gases and vapours to flow under normal operating conditions. Meanwhile, the Pressure/Vacuum Relief Valves protect Digesters against overpressure and limits product loss.

The Cowhorn can be combined with the Elmac Technologies® Foaming Relief Vent to relieve excessive pressure during Anaerobic Digestion foaming.

2. Flame Arresters

The greatest danger during Anaerobic Digestion is ignition of the flammable vapour, resulting in fire or explosion. Elmac has developed a patent-protected range of Flame Arresters that allow gases and vapours to flow under normal operating conditions whilst preventing flame transmission.

UCA Series: In-line Detonation Flame Arresters

The Elmac Technologies® UCA Series of In-line Detonation Flame Arresters prevent gas and vapour explosions in Digester pipeline systems under the most severe conditions of unstable detonation, stable detonation and deflagration.

The UCA Series integrates Elmac’s globally recognised High Energy Dissipation System (HEDS™) and Enhanced-Flow Technology (E-Flow™), resulting in a lightweight, easy to maintain Flame Arrester with higher flow rates and reduced pressure drop.

HEDS™ improves flow rates and operating energy savings by up to 30%, considerably more than traditional Flame Arresters. This innovative system utilises Elmac’s pioneering orifice plate design and optimised crimped ribbon element, allowing gases and vapours to pass through the Flame Arrester whilst attenuating the shock wave, dissipating heat and significantly reducing the intensity of explosions.

EVA Series: End-of-line Deflagration Flame Arresters

The Elmac Technologies® EVA Series of End-of-line Deflagration Flame Arresters protect Digesters against atmospheric deflagrations where the ignition source originates outside the pipeline systems.

The EVA Series integrates Elmac’s E-Flow™ Technology and is optimised using Computational Fluid Dynamics (CFD) to ensure exceptional flow rates and minimal pressure drop.

The innovative design of the EVA Series also incorporates easy-clean, replaceable, crimped-ribbon elements that are less susceptible to fouling and clogging than competitors’ equivalent models.

LEA Series: In-line Deflagration Flame Arresters

The Elmac Technologies® LEA Series of In-line Deflagration Flame Arresters prevent the propagation of flames within Digester piping systems. Any flames and explosions are confined to the immediate area when installed near the potential ignition source.

For a deflagration with no stabilised flame, the combustion products are cooled by heat dissipation at the surface of the Flame Arrester element, preventing the combustion process from continuing. If a flame stabilises on the component, a sudden increase in temperature will activate secondary protection measures to prevent the flammable mixture’s flow.

The LEA Series is available in high pressure, high temperature and short-time burn variants.

3. Pressure/Vacuum Relief Valves

The Elmac Technologies® range of Pressure/Vacuum Relief Valves protect Anaerobic Digesters against excessive pressure and vacuum. Flow through the valves is controlled by weight-loaded or spring-loaded pallets. The pallet’s weight or spring force keeps the device closed and once the pressure or vacuum in the Digester reaches the closing force, the pallet will lift off the seat and allow flow through the valve.

The Pressure/Vacuum Relief Valves integrate Elmac’s innovative Air-Cushioned Sealing Technology, limiting product loss and environmental discharges, alongside bespoke weatherhoods to protect the pressure vent port and mesh screens to prevent foreign matter intrusion.

The geometry of the Pressure/Vacuum Relief Valves provides exceptional flow capacity in a single compact, lightweight and easy-to-handle unit.

Pressure Vacuum Relief Valve - PVRV

4. Foaming Relief Vents

Anaerobic Digestion foaming occurs during the rapid release of dissolved gases within a liquid digestate (mainly methane and carbon dioxide), in a process known as flash evaporation. This quick release of gas causes large volumes of foam to build up in the surface layer of the liquid. Failure to relieve this pressure quickly and effectively can result in catastrophic damage to the roof and supporting structure of the Digester.

The Elmac Technologies® Foaming Relief Vent allows emergency venting during excessive pressure or foaming, eliminating the likelihood of a costly tank rupture.

Elmac’s Foaming Relief Vents automatically operate when subjected to pressures exceeding a predetermined set pressure, alleviating blockage risks to Pressure/Vacuum Relief Valves and ensuring the continued operation of Flame Arresters.

Pressure Protection

Contact Elmac for further information

Elmac’s Flame Arresters and Pressure Protection Equipment are in high demand. Contact us today to secure an on-site Safety Survey with a member of our Technical Team.