The question of the right agitator cannot be answered in a general way. The choice of the right agitator depends on many factors such as:
Application: In the biogas or industrial sector, different requirements are set on agitator technology than in the agricultural sector. For example, while industrial or biogas agitators often require ex proof classification for operation, ex classification does not play a role in the agricultural sector.
Tank geometry: The size and geometry of the tank influence the choice of the right agitator. In general, the larger the tank, the higher the stirring power should be. In most cases, several agitators are used at the same time in larger tanks.
Tank type: The type of the tank is crucial for the selection of the appropriate agitator. Firstly, constructional possibilities must be considered. An open lagoon, for example, does not offer the possibility of installing the mixer on the tank wall or ceiling, whereas a closed tank with a concrete ceiling allows for this installation. Furthermore, the material of the tank (steel or concrete) also matters.
Local conditions: Restrictions under building law, such as noise protection in commercial / residential areas, must also be taken into account. SUMA has developed a special sound insulation for rod agitators for this purpose.
Substrate properties: The dry matter content and viscosity influence the flowability of the substrate. The higher the dry matter content, the more viscous the substrate. (see also question 3) The ph-value of the substrate is also important in the selection of a suitable agitator. For aggressive media, stainless steel agitators such as the OPTIMIX 2A are recommended, otherwise the agitator may be damaged.
Stirring interval / Stirring times: Depending on the agitation requirements and agitator configuration, stirring is carried out in continuous or intermittent operation. The stirring time depends equally on the requirements and should also be considered regarding economic aspects. The specific characteristics of the biogas plant, such as substrate properties, tendency to floating blanket formation etc. must be determined.