COMBUSTION OF CELLULOSIC CHAR UNDER LAMINAR-FLOW CONDITIONS

An experimental and modeling study of cellulosic char combustion under laminar gas flow conditions was conducted covering the temperature range of 473-1173 K with 0.03-0.21 oxygen mole fraction in the feed gas. A gas film mass-transport limited model accurately fits the combustion rates measured in a large-scale thermogravimetric furnace. The best fit correlation to the experimental data predicts that local mass transfer rates are governed by the relationship Sh(x) = 0.221 Re(x) 0.564Sc1/3 and that mass transfer and char combustion rates are proportional to the oxygen mole fraction in the bulk gas raised to the 0.72 power. These results were used to develop an integral reactor model for a countercurrent pilot scale incinerator. Preliminary experiments indicate good agreement between model predictions and actual incinerator behavior.