Biogas monitoring maintenance for zero downtime

Buying a fixed biogas monitoring system, critical to efficient running of the growing number of anaerobic digestion (AD) plants, can seem straightforward compared to the difficulty of ensuring it is kept running cost-effectively over its lifetime. Geotech’s after-sales support options draw on their GA3000 PLUS’s basic design and mean zero monitoring downtime at minimal cost.

As part of an annual support package, the central monitoring unit inside the system can be swapped with a replacement in minutes, between reading intervals for most sites. Gas reading levels to the site’s control system are briefly ‘frozen’ to avoid triggering any alarms while this is done. The sensor unit is then returned to Geotech for a full service and calibration without any on-site disruption or expensive call-out charges. The GA3000 PLUS’s reliability is boosted by housing the most sensitive components inside this separate, robust sub-system.

A 1000kW AD plant can produce around 8,000 MWh a year, so it is vital that the process runs with minimal downtime. Plant technicians regularly check the AD process inside the digester to ensure that gas production is optimised but maintaining the gas analyser monitoring the whole process can be overlooked.  As many analysers are used in harsh and potentially explosive environments, the first indication that something is wrong may be expensive damage to the combined heat and power (CHP) engine and a long period of biogas monitoring or entire plant downtime.

A simple program of on-site maintenance and regular calibration by plant engineers, backed up by remote support if required, will ensure smooth running of the GA3000 PLUS until scheduled servicing. This approach to analysis equipment maintenance keeps costs to a minimum and avoids expensive unbudgeted repairs and call-outs for service engineers. However big bills are not potentially the biggest issue. Unscheduled CHP engine downtime is the biggest potential cost for AD plants across all the sites globally where the GA3000 PLUS is operating.

The sensors used to monitor the key gases, particularly methane (CH4), oxygen (O2) and hydrogen sulphide (H2S) can need calibration or replacement. Not paying attention to this can run the risk of unreliable readings. Poor methane readings could lead to CH4 production at the AD plant not being optimised and undetected rising O2 and H2S levels could lead to costly engine repairs or reduced life of the gas analyser.

Whilst AD plants have different gas monitoring requirements, generally related to the feedstock used, these can be considered and designed into the monitoring system. These include variations in moisture control requirements – particularly important on sites where temperatures fall below freezing – as well as gas line and communication requirements and integrating with other processes on site such as desulphurisation. Geotech’s technical team and global distributor network offer local and remote support, starting with planning which GA3000 PLUS variant is most suitable. Replacement sensor units and spare parts can be sent to site worldwide for quick swap out, either by site engineers or trained, local distributors.