STUDY OF DEWATERING CHARACTERISTICS OF EUCALYPTUS WOOD BY SUPERCRITICAL CO2

Abstract

Wood collapse is a major defect for their applications in solid wood production. Supercritical CO2(ScCO2) dewatering can quickly remove water in wood and effectively reduce the capillary tension leading to collapse of wood structure. In this study, Eucalyptus exsertaF.V. Muellwoodwas dewatered using ScCO2at 35,45,55°Cand 15,20,25 MPa, separately. The dewatering characteristics and wood deformationwere statistically analyzed and compared after dewatering. The results show that the dewatering rateof ScCO2isaffected by moisture content (MC)of wood, showing the higher the MC, the faster the dewatering. Itisalso affected significantly by pressure, indicating increased dewatering ratewith thepressure. The effect of temperature on dewatering rate is not apparent as the pressure is less than 25MPa, but it becomes significantat 25MPacondition, showing an increased dewatering rate with temperature. In this experiment, the greatest dewatering rate was 19.8%·h-1at 55°Cand 25MPa. The transversal shrinkage of all specimens after 5 cycles dewatering waslower than1.5%, indicating the ScCO2dewatering could effectively inhibit collapse of eucalyptus wood structure. Thetransversal shrinkage decreases with the pressure, and is not affected significantly by temperature.