Installation of a Feed-and-Turn Dryer: An Option to improve Heat Utilization and Economy of an existing Biogas Plant

Abstract

Feed-and-turn dryers may be installed in order to use excess heat from biogas CHPs especially in agricultural enterprises with otherwise low heat utilization. These dryers can be used for drying a manifold of agricultural produce. In this case draff, maize silage and saw dust were investigated. The focus was on drying effectiveness, economic benefits and probable changes in chemical composition of the materials investigated. Results demonstrate that the installation of the feed-and-turn dryer is a substantial improvement of the biogas plant. In the case investigated it significantly improves the energy efficiency by increasing heat utilization from 6,669 GJ·a^-1 in 2007 to more than 27,542 GJ·a^-1 in 2009. It provides, in addition, the agricultural enterprise with valuable equipment for producing high quality and high valuable feed and other products.  Finally, on-farm drying generates an additional income compared to purchasing equivalent products or to external drying.