Mixing and fine-tuning: growing support, and one or two practical issues

Landia GasMix systems deployed at Eco Sustainable Solutions 2.5-acre renewable energy site in Piddlehinton.

Mixer and pump manufacturer Landia has welcomed Privilege Finance’s statement that farm-based AD plants can improve efficiency from 10% to 30%.

Citing Feedstock, Mixing and Monitoring as three key areas in which to gain benefits from being more proactive, Privilege Finance’s Technical Director Phil Hobbs recently commented on how poor mixing of digestate will have a detrimental impact on feedstock performance.

Landia’s Key Account Manager Paul Davies said: “Fine-tuning of a farm-based AD plant can bring about significant savings on maintenance and energy, as well as greatly improve gas yields. So, if your plant isn’t realising its full potential, a retrofit of the mixing system – especially one that puts all moving parts on the outside of the tank, can definitely improve efficiency”.

Davies also states that many mixing systems may have 7.5kW motors, but that in most cases, these are running flat out, using 180 kW hours per day.

For what he describes as ‘complete mixing of the whole digester’, Davies suggests farm-based AD operators consider 18.5 kW motors that only have to run for 10-15 minutes per hour, using just 110 kW hours per day.

Landia’s retrofit mixer installation at Eco Sustainable Solutions’ AD plant in Dorset reportedly increased gas yields by 12.5% and also reduced energy usage by 50%, an achievement recognised by ADBA with a Highly Commended honour at its annual awards.

Davies added: “As rightly stated by Privilege Finance, the potential to improve efficiency of your plant is very much attainable. Even if your AD operation seems to be running along adequately, you can fine tune it with a better mixing system to reduce energy and maintenance costs. Together with improved monitoring and better quality feedstock, you can significantly enhance your gas yields”.