THERMAL CONVERSION OF LIGNIN-RICH RESIDUES FROM LIGNOCELLULOSE BIOREFINING: FROM THERMOGRAVIMETRY TO UPDRAFT GASIFICATION

The reported work deals with the use of lignin rich solid, which is available as residue from enzymatic hydrolysis of lignocellulosic biomass, to produce syngas. The tested process was an updraft gasification carried out at pilot scale of about 20 kg/h as dry feed. The thermal conversion of the residue was investigated by TGA in air, carbon dioxide and nitrogen atmospheres pointing out the relative contribute of pyrolysis, combustion and gasification at different temperatures. In the plant tests, the residue was completely converted in gaseous and liquid energy carriers with overall energy efficiency near 90%. Several process conditions were examined corresponding to different flows of O-2 and steam. The molar ratio H-2/CO in syngas increased by using steam as co-gasification agent. Steam was necessary to stabilize the process in the case of using oxygen as main gasification agent. Oxy-steam gasification provided the best results in terms of syngas heating value and highest thermal power output of the plant.