Combination of continuous and discrete event simulation for analyzing biogas plants

The main problem for the economical operation of biogas plants is the seasonal varying energy and biomass consumption. On one hand the fermentation reactors should be refilled with constant material batches, on the other hand the need of the waste heat (55-65% of the energy production) emerging at the electricity production is given for the most part only in the winter. Additional there are seasonal fluctuations in the supply, which are dependent from the share of vegetable. The demand on the constantly produced manure is likewise time-dependent, however because of the good storage life is relatively uncritical. The task of the work was the development of a logistical model of a large biogas-plant. It serves as basis for the forecast of the time-dependent energy-and mass conversion (biogas, manure), reliability and durability of plant components and for clarifying the possibilities for supplying peak power for the regional power supply. At the analysis several aspects must be considered. A plant model consists of a logistic part (supply-stock-production-power/heat-production) with above described time dependencies (inclusively component reliability-maintenance intervals) and an energetical/thermal part (process energy, surplus energy).