Mixing is an essential part of the AD process and System Mix, which markets the Rotamix Dual Zone mixing system, says it has made important recent contributions in supplying mixing equipment to both the Dailuaine and Glendullan distilleries – the latter providing the location for a new bio-energy plant.
Diageo Scotland has a number of distilleries in the ‘Whisky Trail’ area located in Speyside, Perthshire and has invested around £1bn in increasing production capability and enhancing their bio-energy facilities.
The mixing system installed at the Dailuaine Bioplant consists of a single Vaughan HE10R12-381 horizontal end suction chopper pump driven by a 37 kW rated motor and 4 internally floor mounted double nozzle assemblies to mix a 24.5m diameter digester tank. The success of this initial AD project was an important factor in the decision to upgrade the bio-energy plant at the Glendullan distillery, where another single pump mixing system is operating successfully.
Production residues such as spent grains and pot ale form the bulk of the materials which are fed into the bioplants which ultimately produce outputs of biogas of up to 500 kWe CHP and are used to power the distilleries.
As the sole UK suppliers of the bespoke design Rotamix (for digester mixing) and STM (short for “small tank mixing”) tank mixing systems, both of which use the integral Vaughan chopper pump, System Mix says it is making an important contribution to the success of AD plants in the food waste sector. Operators are benefitting from its technology and experience resulting in its involvement in many ‘retrofit’ projects where the existing mixing systems (or lack of them) were contributing to operational and biological issues.
For example, problems such as solids settlement are commonplace, and have the effect of reducing active digester volume. This can result in a significant reduction in output, leading to failure to meet compliance requirements. Also, compressors in ‘traditional’ gas mixing systems and submersible in-tank propeller systems are often associated with labour-intensive maintenance issues, resulting in process downtime and associated costs.
Andy Parr, Director at System Mix comments: “Today AD operators need to maximise the sustainable credentials of their plant and equipment even further and we are confident that the benefits of our mixing systems are becoming even more relevant and important”.
