Lab-based research studies for optimizing the methane yield and managing the process control of anaerobic digestion of renewable raw materials developed an automatic filling device that continuously loads the fermenter system with substrates.

Automatic batching

Investigations should be carried out with different energy crops, which are used for methanization as a monosubstrate and in mixes. It is essential to ensure that the lab-based systems can be loaded over two days, without manual intervention.

Substrates are inhomogeneous mixes (silage), in which demixing and variation caused by drying out or anaerobic decomposition, are to be avoided. There are similar requirements to be met in automatic feeder technology. Which is why the components of automatic TMR feeders for sheep have been modified accordingly.

The base is an enclosed stainless steel hopper with a substrate conveyer and dispersal system and a precision-controlled batching auger. This conveys small quantities of the material to a scale pan, in which the weight of the batched quantity is checked down to the last gram before being loaded into the fermenter.

A process control regulates the timing for batching and logs the batched quantities. Any variation from the target quantity can be automatically corrected for each subsequent batching process.

For average volumetric loadings of 1 to 3 kg /m3 and corn silage, it is possible to obtain good results with daily variations from the target value of less than 10 g. There are constraints with a lower volumetric loading, that is, daily batched quantities in the less than 10 g range, as well as for materials that dry out a great deal (grass silage, for example). Work is being done on a modified storage and dispersal system, so that the batching device can be used for these substrates as well.