Operating Experiences with a Small-scale CHP Pilot Plant based on a 35 kWel Hermetic Four Cylinder Stirling Engine for Biomass Fuels

Within the scope of the RD&D project presented a small-scale CHP plant with a hermetic four cylinder Stirling engine for biomass fuels was developed and optimised in cooperation with the Technical University of Denmark, MAWERA Holzfeuerungsanlagen GesmbH, an Austrian biomass furnace and boiler manufacturer, and BIOS BIOENERGIESYSTEME GmbH, an Austrian development and engineering company.

Based on the technology developed, a pilot plant was designed and erected in Austria. The nominal electric power output of the plant is 35 kWel and the nominal thermal output amounts to approx. 220 kWth. The plant operates fully automatically. Currently, this plant has run for more than 5,000 hours using wood chips as fuel with very satisfactory results.

Problems to be addressed are primarily regarding an enhanced electric efficiency. Major emphasis will be placed on improving the efficiencies of the hot heat exchanger of the Stirling engine, of the air preheater and of the entire combustion system. Furthermore, the optimisation of the pneumatic cleaning system to reduce ash deposition in the hot heat exchanger is of great relevance.