Page 19 - Biogas Plant Construction

Biogas Plant Constructions 361

Fig. 20. Schematic of the GPU (Chandrasekar, 2006)

6.3 Mixing technology
The types of mechanical mixing (Fig. 21) are: vertical mixing, horizontal mixing, and side
mixing. Submersible motor mixing devices are usually used in commercial biogas plants.
Each device is provided by a cable and gear protection system (Fig. 22). Light agitation
increases the velocity of digestion, differently from heavy agitation which decreases the
velocity of reaction. In digesters with capacities higher than 100 m 3 , it is necessary to install
equipment to provide agitation of the contents.

(a) Vertical mixing (b) Side mixing

(c) Horizontal mixing
Fig. 21. Mechanical mixing

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