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Waste to Energy

Biogas utilisation (cogeneration operation) / saving energy

Biogas utilisation (cogeneration operation) / saving energy

The obtained biogas is converted to heat and power in a cogeneration power plant. The electrical energy produced is fed into the local main power grid at the feed-in tariff via a transformer station at the site.

The waste heat from cogeneration is in turn used to heat e.g. the fermentation boxes, the percolate tank as well as the equipment and staff rooms at the plant.

The fermentation plant’s own need for heat and power is comparatively low. The vast majority of the produced heat is available for external power and heat consumption.

Process control engineering

The plant’s hardware is controlled via a PLC system (SIEMENS S7 SIMATIC programmable logic controller). It also facilitates the remote monitoring of the plant. All the sample-taking tools integrated into this system, such as temperature and pressure sensors, meet the current industry standard.

The plant’s software is controlled via a PCS (process control system with WinCC visualization). If need be, certain operating parameters can be manually changed via this surface. In normal and regular operation, the BEKON dry fermentation plant is controlled fully automatically for the most part.

Malfunctions in operation are directly recorded and classified by the automatic control unit of the integrated warning and fault reporting system. In the case of safety-relevant malfunctioning, the plant switches to a safety mode on its own. Even in the case of a loss of power, etc., this technology reliably prevents critical system states.

All malfunction warnings are transferred by the process control system directly to a mobile phone via a text message and archived with all the relevant information in the report storage area.

Agro-Energy ... The BEKON DCF Plant

Fermentation process

The extracted percolate is stored and heated in the inner ring of the round digester.

This percolate is used for the inoculation of fresh material and the constant percolation of the fermentation substrate, and is systematically returned the main digester in a computer-controlled pattern.

Excess percolate from the inner ring is pumped into the storage tank.

The temporarily stored percolate can be picked up by substrate suppliers with tankers and used as liquid fertilizer on agricultural land after the material separator phase. The pressed solid fermented substrate is also used as organic fertilizer on agricultural land.

The amount of power (without cogeneration) required for BEKON DCF plants amounts to only 2.0-3.0 % of the total power generated. There is also no expensive maintenance, repair and replacement work on fixed stirring units. This directly impacts the long-term return on investment of the plants.

For the filling of a BEKON DCF plant, an automatic feed system (feed silo) is installed, and the charging device is filled roughly 1 to 2 times per day. The supplied material is dumped into the feed silo with a wheel loader or a telescope loader.

The charging device is located right next to the round digester. At the base of the storage container, a floor conveyor is installed to convey the substrate to a dosing station fully automatically. In the next step, a corresponding acceptance conveyor feeds the material into a closed mixing pump that consists of a screw conveyor and an eccentric pump. This pump facilitates the best-possible mixture of fresh substrate and inoculated fermented substrate before the mixture is conveyed to the digester.

The material is removed via a fully automatically controlled discharge pump to a screw press that drops the solid material in an already provided collection container or in a covered storage area. The remaining liquid fermented substrate is temporarily stored in an open or closed tank. Depending on the dry substance content of the fed materials, the amount of the liquid fermented substrate may be very low.

The BEKON DCF plant is controlled fully automatically via a computer-assisted control system. The various process parameters in the percolate circulation, for the heating of the digester, can be viewed at all times in the gas system and the cogeneration operation, and may be adjusted automatically.

Process technology

The plant’s hardware is controlled via a PLC system (SIEMENS S7 SIMATIC programmable logic controller). This also facilitates the remote monitoring of the plant. All the sample-taking tools integrated into the system, such as temperature and pressure sensors, meet the current industry standard.

The plant’s software is controlled via a PCS (process control system with winCC visualization). If need be, certain operating parameters can be manually changed via this interface. In normal and regular operation, the BEKON DCF plant is controlled fully automatically for the most part.

Malfunctions in operation are directly recorded and classified by the automatic control unit of the integrated warning and fault reporting system.

In the case of safety-relevant malfunctioning, the plant switches to a safety mode on its own.

Even in the case of a loss of power, etc., this technology reliably prevents critical system states.

All malfunction warnings are transferred by the process control system directly to a mobile phone via a text message and archived with all the relevant information in the report storage area.