Improving Pressure Monitoring and Compressor Protection in Biogas Plants

Biogas facilities play an important role in turning organic waste streams, including manure, sludge, and industrial waste, into renewable energy. However, the process depends on more than biological activity inside the digester. Reliable pressure monitoring, equipment protection, and safe system response are critical to keeping operations running efficiently.

In biogas applications, methane generation creates pressure within digesters and associated systems. If pressure is not properly monitored, or if supporting equipment such as air compressors fail, facilities can face downtime, equipment damage, safety concerns, and increased maintenance demands.

For one European biogas plant, the challenge was finding a more reliable and practical way to monitor digester pressure, supervise compressed air pressure, and protect compressor operation while meeting strict safety requirements.

The Challenge: Reliable Monitoring in a Safety-Critical Process

The biogas facility operated multiple digesters where gas accumulation created pressure on seal hatches and connected equipment. Operators needed a dependable way to monitor pressure at each digester seal hatch, while also supervising pressure in the main compressed air line.

A key concern was compressor reliability. If the primary air compressor failed, the facility needed instrumentation that could help trigger a backup compressor quickly and communicate the condition to the plant control system.

The plant required a solution that could:

• Monitor digester seal hatch pressure
• Supervise main compressed air line pressure
• Help protect against primary compressor failure
• Automatically activate a backup compressor when required
• Communicate with the PLC for alarms or corrective actions
• Meet hazardous area and functional safety requirements

The customer also wanted to reduce system complexity. Their existing instrumentation approach was costly, difficult to support, and limited in functionality. A more integrated solution was needed.

The Solution: Integrated Pressure Monitoring and Safety Response

The facility selected the United Electric Controls ONE Series Transmitter with a 20 bar measuring range. The transmitters were installed on the digesters and along the compressed air line to provide continuous pressure monitoring and control support.

The ONE Series Transmitter helped simplify the pressure monitoring system by combining multiple functions into one device. In the event of a main air compressor failure, the transmitter’s safety relay can trip within 100 milliseconds, helping activate the backup compressor. At the same time, a discrete output can send a signal to the PLC, allowing the control system to trigger alarms, notifications, or additional corrective actions.

This integrated approach reduces the need for multiple standalone devices and helps simplify installation, commissioning, and maintenance.

Key Advantages for Biogas Applications

Integrated Outputs in One Device

Biogas facilities often require several layers of monitoring, control, and safety response. The ONE Series Transmitter combines pressure measurement, safety switching, relay outputs, PLC communication, and local programming in one compact instrument.

For operators, this means fewer separate devices, reduced wiring and installation complexity, and a more streamlined monitoring approach.

Fast Response for Compressor Protection

In a process environment, response time matters. A delayed response to compressor failure or abnormal pressure conditions can lead to downtime, process disruption, or equipment concerns.

With rapid relay switching, the ONE Series Transmitter supports fast action when operating conditions fall outside the desired range. This helps maintain plant reliability and provides added protection for critical equipment.

Local Visibility for Operators

The integrated LCD display allows operators to view real-time process pressure and monitor conditions directly at the device. This is useful for routine inspections, troubleshooting, and confirming system status without requiring additional equipment.

Flexible Local Programming

The transmitter can be configured locally using the keypad. Operators can adjust setpoints, configure deadbands, modify operating parameters, and fine-tune performance based on the application.

Deadbands can be programmed up to 100% of the measurement range, giving facilities flexibility to adapt the device to different process requirements.

Safety Certifications for Hazardous Environments

Biogas facilities can involve methane and hazardous operating conditions, making safety-certified instrumentation an important requirement. The ONE Series Transmitter supports these applications with ATEX approval, SIL2 and SIL3 capability, and independent third-party exida SIL certification.

Results: Reduced Complexity and Improved Confidence

Following installation, the biogas facility improved its ability to monitor digester seal integrity and compressed air system pressure. The solution also supported automatic backup compressor activation during primary compressor failure, helping reduce downtime risk and improve operational reliability.

By integrating pressure monitoring, safety switching, local display, relay outputs, and PLC communication into one device, the plant simplified its instrumentation approach while meeting its safety requirements.

A Practical Fit for Canadian Biogas Facilities

For Canadian biogas, wastewater, agricultural, and industrial energy facilities, pressure monitoring is a critical part of safe and reliable operation. Applications involving digesters, compressed air systems, methane generation, and backup equipment require instrumentation that is accurate, responsive, and suited for demanding environments.

The United Electric Controls ONE Series Transmitter provides a practical solution for facilities looking to improve pressure monitoring, simplify system design, and support safety-critical process control.

Westech Industrial is a Canadian distributor for United Electric Controls and supports customers with product selection, application review, and instrumentation solutions for biogas and other energy-sector applications across Canada. For more information visit our website at https://westech-ind.com or call us today at 1-800-912-9262.

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