Effects of Pyrolysis Conditions on Yield of Bio-Chars from Pine Chips

The influences of temperature, heating rate, purge gas type, and flow rate on the yield of chars produced from pyrolyzing southern pine chips were investigated. Pyrolysis temperatures were between 450°C and 1,000°C, with heating rates of 0.5°C/min, 1.0°C/min, 10°C/min, 30°C/min, 50°C/min, and 100° C/min. Purge gases, nitrogen (N₂), hydrogen (H₂), and N₂–H₂ mixture (10% H₂), were used at flow rates from 100 to 1,000 mL/min. Pine char yield decreased as temperature, heating rate, or purge gas flow rate increased. Two regions with significantly different decrease rates of pine char yield can be identified for temperature or heating rate as they increase. The yield decrease rate turning points were 550°C and 10°C/min for yield-temperature and yield-heating rate charts, respectively. The pine char yield was lowest when hydrogen was the purge gas and highest with nitrogen.