Monday, April 29, 2013
Exhibit Hall
The lignin fraction of lignocellulosic biomass usually ranks second as mass percentage. Although the well recognized biological and structural role that lignin plays in plants, in bioprocessing it is mostly a problem to be removed or bypassed with appropriate methods. In pulp paper industry black liquors that contain lignin are burnt and provide energy to the whole process. The hydrolytic lignin is a byproduct of the 2nd generation ethanol or similar bioprocessing that exploit the carbohydrates and leaves the unreacted lignin as solid residue. In the case of ENEA’s biorefinery, after continuous steam explosion treatment, at around 200°C, the biomass undergoes to an enzymatic hydrolysis and the hydrolysate if fermented to ethanol (or other chemical); after removing the ethanol, or other desired product, the slurry is filtered. The resulting cake is rich of lignin but, beside about 50wt % of water, contains also unconverted fibers and residues of the previous processing (enzyme fragments, yeasts, nutrients, free sugars). For the work we are reporting, two batch of lignin (from wheat straw and reed) were analyzed to determine volatile and fix carbon, ash, C,O,H,N,S,Cl, LHV and HHV. The lignins and the derived chars were investigated by TGA under oxidizing and inert atmosphere (mixtures of O2, N2, CO2) to determine the pyrolysis, combustion and gasification behaviors, included the relevant activation energies, reaction orders, half conversion times. The kinetics data obtained at the microscale were used to plan trials with a fixed bed updraft gasifier of 200kWth and discuss the obtained results.