266397 Hydrothermal Carbonization of Lignocellulosic Biomass Using Salts
As we progress toward a paper-free society, vast quantities of valuable renewable lignocellulosic biomass become available for other uses. However, there are challenges to transporting and using biomass as an energy source. As harvested, biomass has a high water content, making it perishable during shipping. Drying biomass can be energy intensive and expensive. In addition, its fuel value (HHV) is low compared to that of coal. With hydrothermal carbonization, high moisture content lignocellulosic biomass is heated in water to temperatures of about 260̊C, at a pressure high enough to keep the water liquid. This process renders the biomass hydrophobic, and thus less subject to decomposition during transport, as well as increasing its fuel value.
The reactions which occur in hydrothermal carbonization increase the fuel value of the solid product. The addition of salts to the biomass and water reactants can enhance these reactions so that HHV is further increased. Salt addition also decreases the minimum pressure required to maintain liquid water.
Ca propionate, Ca acetate, Mg acetate, Ca lactate, Li chloride, Ca chloride, and Ca formate were tested in hydrothermal carbonizations at 260ºC for 5 min using loblolly pine as a biomass. Li chloride, Ca chloride, and Ca lactate were found to increase the HHV of the solid product, as well as reduce reaction pressure. The addition of Ca in coal co-firing has been found to reduce SOx and NOx emissions in the literature. Therefore, adding extra calcium to a solid fuel product may reduce the need for emission scrubbing in a power plant. Adding Ca chloride or Ca lactate to a biomass co-firing fuel may enhance the power generation process.