Abstract: A fermenter for biogas plants, including a submersible motor-driven stirrer that can be vertically adjusted by means of a motor. During operation of the biogas plant, the fermenter is filled, to a level, with substrate that is to be fermented, and the agitator blades of the submersible motor-driven stirrer are fully immersed in the substrate. According to the invention, a level gauge is provided, by means of which the level of the substrate is detected and a corresponding level measuring signal is generated as an actual level signal. Furthermore, a control device is provided, to which the level measuring signal is fed and which controls the vertically adjusting motor for the submersible motor-driven stirrer in such a way when a lower level is detected that the stirrer is lowered and the agitator blades continue to be fully immersed in the substrate.

Abstract: A fermenter for biogas plants, including a submersible motor-driven stirrer that can be vertically adjusted by means of a motor. During operation of the biogas plant, the fermenter is filled, to a level, with substrate that is to be fermented, and the agitator blades of the submersible motor-driven stirrer are fully immersed in the substrate. According to the invention, a level gauge is provided, by means of which the level of the substrate is detected and a corresponding level measuring signal is generated as an actual level signal. Furthermore, a control device is provided, to which the level measuring signal is fed and which controls the vertically adjusting motor for the submersible motor-driven stirrer in such a way when a lower level is detected that the stirrer is lowered and the agitator blades continue to be fully immersed in the substrate.