Impact of organically bonded potassium on torrefaction: Part 1. Experimental

The results show that K and Na bound to organic sites can significantly increase the mass loss during torrefaction at temperatures between 240 and 280 °C for a fixed time and temperature. It is also seen that Mn bound to organic sites increases the mass loss while Ca addition does not influence the mass loss rate during torrefaction. This increase in mass loss during torrefaction with alkali addition is unlike what has been found in the case of pyrolysis where alkali addition resulted in a reduced mass loss. These results are important for the future operation of torrefaction plants which will likely be designed to handle various biomasses with significantly different contents of K. The results imply that shorter retention times are possible for high K-containing biomasses.