| Abstract:It has become a development trend that the black liquor was burned at a high solid content in alkali recovery unit. Hence, it is significant to learn and master the rheological properties of thick black liquor in order to optimize the combustion technology. The change rules of storage modulus G′, loss modulus G″, loss factor tanδ and dynamic viscosity η′, which were important indicators of the dynamic viscoelasticity of thick bamboo kraft pulping black liquor, were investigated by using a rotational rheometer in this article. The results proved that thick black liquor still exhibited obvious elastic solid properties at high temperature. In addition, dynamic viscosity showed distinct shear-thinning behavior. Black liquor could be softened by increasing the temperature. meanwhile the relaxation time of chain segments and dynamic viscosity were decreased, therefor, the flow resistance of black liquor was reduced. Cross model could very well describe the relation between η′ of thick black liquor and angular frequency ω under high temperature conditions. However, the Carreau-Yasuada model could not be used to describe the relation between loss angle δ and ω． |
