Ash Deposition and Fouling Tendency of Two Energy Crops (Cynara and Poplar) and a Forest Residue (Pine Chips) Co-fired with Coal in a Pulverized Fuel Pilot Plant

Biomass is presented as a valuable alternative to partially substitute fossil fuels to decrease CO2 emissions. Two different energy crops (cynara and poplar) were co-fired with a South African coal in a 500 kWth pulverized fuel pilot plant to analyze their fouling tendency at different shares. Results were also compared to a pine residue, and finally, the coal was substituted in cynara co-firing by a high sulfur sub-bituminous coal to see its effect on ash deposition. Deposit samples from a deposition probe were analyzed with scanning electron microscopy/energy-dispersive spectrometry and inductively coupled plasma–optical emission spectroscopy techniques, and results were evaluated together with different theoretical indexes. No operational problems were found in the tested shares (up to 15% biomass energy based). Nevertheless, coal appeared to have conclusive influence on ash deposition, which was more important for the sub-bituminous coal tested. Alkali chlorides were destroyed in all of the cases, bec...