Abstract
This paper describes the recovery of valuables such as organic acids and inflammable gases from biomass using a superheated steam (SHS). SHS is a thermal radiation gas which little contains oxygen and can pyrolyze (carbonize) organic materials in a short time at relatively low temperatures without burning. As an example of biomass to be treated, we dealt with wood wastes (Hinoki wood). A closed cylindrical vessel connected with a water supply pipe and an exhaust tube was used as a carbonization furnace and heated in an electric furnace. The wood samples with a cubic shape were carbonized in the superheated steam or nitrogen atmospheres under various conditions. As pyrolysis products, non-condensable gases, condensates (water and oil phases) and solid residues (i.e., charcoal) were obtained. The volume of hydrogen and methane gases contained in the non-condensable gases increased exponentially with an increase in the carbonization temperature. The concentration of organic acids such as acetic acid and lactic acid contained in the aqueous condensates increased with an increase in the carbonization temperature; however, the concentration of each organic acid was almost constant at carbonization temperatures above 673 K. From the analysis of pore characteristics of charcoals obtained in both superheated steam and nitrogen atmospheres, it has been proven that the carbonization in the superheated steam atmosphere progresses rapidly at low temperatures.
