KSB Service GmbH offers biogas plant operators a comprehensive refurbishment package designed to increase the methane gas yield of biogas plants and reduce energy consumption through installed machine components.

The basis of such refurbishment projects is an assessment of an active digester. The service specialists conduct an extensive material-flow management evaluation, taking into account process-specific, hydraulic and machinery-related aspects. They assess, for example, the efficiency of the installed mixers with regard to energy consumption, the correct adjustment of the jet direction and the effectiveness of the biochemical processes.

The service specialists then devise a concept which, in addition to incorporating economical electric motors and high-efficiency mixers with propeller blades that generate an especially strong thrust, may also include proposals for improving process-specific aspects by modifying the feedstock quality and how the feedstock is added.

If the operator decides to refurbish a biomass-filled digester, the service engineers will open the roof and replace or modify the existing mixers. To do this, they can use two TÜV-tested tools which have also been approved by the trade association.

The first tool is a specially developed service cage that is lowered into the digester from a crane. It is fitted with breathing equipment and offers the highest level of safety for the service personnel and, of course, for the operator.

Should problems arise with the installation parts of the mixer, there is also an eight metre-long service pipe with an interior diameter of 1.2 metres. This is positioned around the installation parts on the floor of the digester. A laterally fitted pump empties the service pipe into the digester and allows the personnel to perform work on the concrete floor. The pipe is ventilated externally. Additional safety equipment, such as a harness, rope brake, winch and a "dead man's switch", is used to secure the service engineer. These safety precautions are necessary, as fatal accidents have happened in the past due to residual methane gas. Thanks to the service pipe, the operator does not need to empty the digester, resulting in huge savings. KSB Service GmbH is currently the only German operator of such certified tools.

There are around 8,000 biogas plants in Germany, many of which are outdated in terms of energy efficiency. This concerns the mixers, which are responsible for mixing the substrate and ensuring the necessary circulation, and the processes that take place inside the digester. Both elements have a major influence on the gas yield and thus on the economic efficiency of a biogas plant. Based on the initial experiences of KSB's service specialists with refurbished plants, depending on the extent of refurbishment required, the investment in energy-saving technology can often pay for itself in just one year.

KSB service engineers use the newly developed service cage to remove a mixer from the digester of a biogas plant.

distributed by