Agriculture Energy Water & Ocean

Daewoo invests in new Mixel mixers for biogas plant

Written by Louise Davey

Mixel, who have supplied almost 50,000 agitators worldwide, have completed the installation of new 24m agitators for a 3,500m3 biogas digester run by Daewoo E&C (Engineering and Construction) in South Korea.

Equipped with 8m diameter blades and a 22kW motor, the bespoke DIGIMIX agitators from Mixel are utilised to mix a co-digestion feedstock of sewage sludge and organic waste to produce electricity and hot water.

To prevent material from attaching itself to the shaft and blades, Mixel (established 1969) designed and built long-lasting, reversible agitators. This followed Mixel’s initial use of simulation software, which analysed the density, viscosity and volume of the materials to be agitated, as well as the variation in tank levels to ensure that there are no dead zones.

Maximising the contact between the organic matter and the bacteria that digest it to produce biogas, the Mixel agitators are highly effective and robust, but actually low in energy consumption because they only need to operate for five minutes per hour. However, even this low duration of agitation works very effectively to separate methane from sludge, and prevent the formation of a floating layer on the top of the digester.

ATEX-compliant, equipped with a guiding turret and conical roller bearings to guide the long agitation shafts, the top-entry Mixel agitators benefit from a hydraulic seal without wearing parts for almost zero maintenance.

Available in shafts up to 25m in length and in motors up to 37kW, Mixel’s DIGIMIX is designed with two levels of self-cleaning TTF propellers that maintain the energy efficiency of DIGIMIX and avoid tow retention.