Giving It Air:
How an oxygen generator can improve efficiency and reduce odours
Atlas Copco is supporting Iona Management Services (IMS) in the production of high-quality biogas, by ensuring a reliable supply of pure oxygen at the Leeming Biogas facility in North Yorkshire.
The Leeming facility generates over five milli
on cubic metres of biogas from food waste feedstock annually, which is upgraded to biomethane and injected into the local gas grid. It also produces PAS110 accredited digestate that is used on nearby farmlands.
Atlas Copco supplied the original oxygen generation equipment via the EPC contractor when the anaerobic digestion facility was originally built and has since also supplied two additional air compressors.
Given that anaerobic digestion comprises a series of biological processes that use microorganisms to break down biodegradable material in the absence of oxygen, this might seem counterintuitive. But the use of oxygen to control biological can pay dividends.
Pure oxygen
James Smith, IMS General Manager for the Leeming Biogas plant, explains:
“It may seem counterintuitive, but oxygen is fundamental to the generation of grid-quality biogas. It stabilises the biological activity inside the fermenters, which promotes efficient gas generation and helps to reduce unwanted by-products such as hydrogen sulphide.”
Hydrogen sulphide (H2S) is a key concern at the Leeming facility as there is a high sulphur content in processed food waste. Highly flammable and corrosive, H2S poses safety risks and damages equipment. Furthermore, its strong ‘bad eggs’ odour also affects site operatives and the local community, making its removal a priority for IMS.
Mixing oxygen with H2S causes a chemical reaction, producing S + H2O, allowing the sulphur to travel in the water. It is a natural way to prevent H2S and issues it can cause. Dosing needs to be closely monitored and carefully managed in balance with the biology.
“The Atlas Copco oxygen generator enables us to use pure oxygen to regulate and control biological activity in the fermenters. This reduces the need for expensive and potentially hazardous chemicals, which is better environmentally and reduces total cost of ownership.” continues James.
As a gas-to-grid site, the amount of oxygen allowed in the final gas stream is also strictly limited, to less than 1% for injection into the grid. The reliable source of high-purity oxygen from Atlas Copco’s OGP10 oxygen generator makes controlling the levels easier, although the process requires regular manual intervention rather than automated dosing.
Reliable on-site O2 generation
An Atlas Copco OGP10 oxygen generator offers 90% to 95% oxygen purity at ISO 8573-1 Class 1.2.1 standard to meet customer quality requirements. It uses proven Pressure Swing Adsorption technology (PSA) to isolate oxygen molecules from other molecules in compressed air, resulting in high-purity oxygen at the outlet of the generator. This enables the OGP10 to deliver a reliable supply of oxygen 24/7, at the exact purity required for the application and with its low operating cost and minimal maintenance requirements.
Feeding the OGP10 with air is an Atlas Copco GA15FF rotary screw compressor. Iona also has a G15L FF compressor as back-up, associated filtration and oil-water treatment equipment, plus an air receiver and an oxygen receiver. It also has a small piston compressor for plant duties.
Having completed 60,000 hours of running, the OGP10 and compressor installation have provided Iona with an economical and efficient alternative to using third-party oxygen suppliers. Onsite oxygen generation also contributes to more sustainable operations by eliminating the carbon footprint associated with multiple oxygen tank deliveries.
Atlas Copco provides ongoing support to maintain equipment on-site to manufacturer specifications, including third-party equipment as well as its own oxygen generator and air compressors.
Sustaining growth
In addition to the reliability and performance of its OGP10 oxygen generator and compressors, IMS is very pleased with the service it receives from Atlas Copco. Integration with the on-site team, good response times and detailed reporting save IMS time, enabling them to focus on optimising biogas production.
In conclusion, James says:
“At IMS, we believe that low carbon energy projects are one of the fastest ways for consumers to embrace the necessary transition to a sustainable economy. However, renewable energy generation is a dynamic industry, and innovations are being made all the time. Atlas Copco keeps me and my team abreast of new technological developments that could add further value to our operations, such as improving efficiency, and are committed to supporting our sustainability goals.”
For more information about Atlas Copco oxygen generators, please click here.
Iona Management Services (IMS) is one of the UK’s leading independent service providers within the low carbon renewables sector. Alongside other disruptive technologies, they provide operations and maintenance services on-demand to anaerobic digestion, combined heat and power (CHP) and biomass projects. Leeming Biogas became part of its portfolio in 2014.
