Performance evaluation of an electrostatic precipitator in a small-scale biomass boiler by using different biomass feedstocks

In order to evaluate the performance of an electrostatic precipitator (ESP), comprehensive test runs investigating both particulate matter (PM) and gaseous emissions were performed by using softwood pellets as well as alternative biomass feedstocks such as short rotation coppice (poplar) and biomass residues (maize). An ESP was directly integrated in a commercially available small-scale biomass boiler. Based on wet chemical analyses of the fuels, so-called fuel indexes were calculated to deliver primary information on the expected combustion behaviour. The overall aim was to determine appropriate operating conditions, to optimise combustion parameters in order to minimise PM and gaseous emissions as well as to inhibit ash related problems. This was done by an efficient combination of primary (air staging in combination with an innovative control system) and secondary measures (integration of an ESP) and showed an enormous potential for both, a stable plant operation and reduced PM emissions. Thus the findings provide the basis for developing a fuel flexible, low emission and highly efficient biomass boiler in the sector of small-scale combustion systems.