EX-11 is a slow-speed vertical paddle mixer with an 11 kW drive for biogas tanks 5, 6, 7 or 8 m high. Paddles arranged at several levels mix the substrate gently, distribute fresh feedstock and help control floating layers. A suitable operating regime supports bacterial colonies and stable anaerobic digestion. The complete configuration includes the drive, vertical shaft, paddles, roof frame, bottom support and sealing components. Paddle geometry is selected for the tank.

Low-speed mixing is intended to combine substrate circulation with gentle treatment of bacteria. With a suitable operating programme, it can favour the formation and preservation of bacterial colonies and their cooperation in the biological processes of biogas production. Excessively intense mixing and high shear can disrupt these colonies and impair bacterial interaction. The effect depends on paddle geometry, tip speed, substrate properties and mixing duration, not rpm alone. The aim is sufficient circulation without unnecessary mechanical stress; lower speed by itself does not guarantee a higher gas yield.

The mixer is mounted vertically through a concrete roof. Its planetary geared drive remains outside the tank, while the main tube carries the mixing elements inside. Paddle levels are set before installation to suit the working liquid depth. The family supports arrangements with four to eight paddles; the exact number, diameter and position are agreed in the drawing. The main tube in this reference series has a diameter of 200 mm. Metal components exposed to the gas atmosphere are stainless steel. A roof mounting frame transfers the drive loads to the structure, and a fixed floor bracket guides the lower end of the shaft. The roof interface and shaft penetration are sealed. The listed height is the tank height, not the shaft length or liquid level. Removing the mixer without emptying the tank requires a suitable large or folding mounting frame, lifting access and the approved service procedure.

The agitator keeps the substrate moving, distributes incoming material and supports contact between the biomass and the active microbial population. Regular mixing helps break up floating layers, mobilise settled material and release gas trapped in the substrate. The operating programme is matched to feeding, gas production and the actual consistency of the medium. Mixing intensity and running time are selected together; motor power alone does not define the performance of a complete tank.

Selection considers the tank geometry, working volume, minimum and maximum liquid levels, viscosity, dry matter content and fibre length. The dry matter figures are application guidelines, not universal limits for every feedstock. Sand, grit and other abrasive contaminants affect wear and the choice of seals and protective components. The number and position of agitators are determined for the tank, including internal columns, heating pipes, feed inlets and withdrawal points.

The electrical installation is coordinated with the site supply and control system. Voltage, frequency, motor protection and any hazardous-area requirements are confirmed for the selected configuration. A frequency converter and its starting and stopping ramps must meet the drive requirements. The catalogue designation does not imply that a control cabinet, converter or site cabling is included. These items are listed separately when required in the supply schedule.

Modular construction provides access to serviceable drive, bearing and sealing components. Inspection intervals, lubrication and replacement procedures follow the operating instructions for the supplied machine. The permitted daily running time and liquid level are set during commissioning. Service without emptying the tank is possible only for the components and procedures provided for by the approved design; the complete machine is not described as maintenance-free.

Paddle diameter, speed, torque, liquid levels and allowable substrate properties are confirmed for the selected configuration. Values from other motor or gearbox versions are not interchangeable.