Biogas production and composting

Organic waste – raw material for biogas and compost

Organic waste is created by private households, industry and food processing plants. 80 to 150 m³ of biogas can be generated from one metric ton of organic waste – that corresponds to 55 to 100 l of heating oil. After being delivered, the organic waste is shredded and machine-sorted into substrate and structure components. The substrate is then fed via a buffer tank into the multi-stage fermentation process which, at 55 °C (131 °F), operates in a “thermophilic” temperature zone. Fermentation sludge and biogas are the end products of this process. The fermentation sludge is mixed with the structure mass to create high-grade compost products. The biogas generated in the reactors is collected in gas storage tanks and later converted into heat and electricity in a combined block heat and power plant.

Backup detection with VEGACAP 66

The substrate is brought to the buffer tank via belt or screw conveyors. A fully insulated VEGACAP 66 capacitive cable probe detects irregularities and prevents backup or overfilling of the buffer tank. Depending on the temperature, steam may form in the buffer tank. Completely uninfluenced by this, VEGACAP 66 continues to function reliably.

Level measurement in the reactor with VEGAPULS 66

To ensure efficient fermentation, the optimum levels of the individual reactors must be ensured. The typical process conditions in the reactors include layered gases, temperatures up to 55 °C (131 °F) and multistage agitators. For this reason, VEGAPULS 66 radar sensors with large horn antennas are implemented for continuous level measurement.
These instruments measure the level with extreme precision, even under these difficult process conditions.

Overfill protection according to WHG with VEGACAP 64

The mandatory overfill protection according to WHG is realised with a VEGACAP 64 capacitive rod measuring probe. It is fully insulated and buildup-insensitive, therefore it delivers an exact switching point even with strongly adhering product.

Pressure measurement with VEGABAR 52

To monitor gas generation in the reactors, gas pressure of only a few mbar is measured continuously. The VEGABAR 52 pressure transmitter is recommended for this task. Its ceramic CERTEC measuring cell provides the small measuring ranges required for this precision measurement.