The inorganic chemistry of the combustion of aspen wood with added sulfur

The inorganic chemistry of the combustion of 100 gm of aspen wood was calculated at 4 and 10 atm with 0.115 gm of added sulfur. The sulfur reacted with potassium and calcium to form a liquid sulfate phase which crystallized at 908°C at 4 atm and 912°C at 10 atm and eliminated a fouling and potentially corrosive molten carbonate phase which would have been present between 800 and 900°C with no added sulfur Blander, M. et al., Biomass and Bioenergy, 1995, 8, 29–38. Deposition of the refractory solids from the combustion gases at about 1000°C before adding sulfur would raise the temperature below which no liquid will form to almost 1000°C. The mole fraction of SO2 in the gas was well below 10−9 before cooling to 700°C at 4 atm and before 800°C at 10 atm. Even by almost doubling the sulfur, it was below this limit before cooling to 600°C indicating a buffering effect of the assemblage of condensates and the gas. Measured sulfur additions to the basic inorganic materials in burning wood should improve the performance of wood in combustors. If the solids produced can be separated from the gas by a cyclone and/or filters, sulfur additions might make aspen wood a reasonable candidate for fueling an efficient turbine.