Microscopic Investigation of Carbonaceous Substances Formed in Coal Liquefaction Reactors.

For the purpose of revealing the progress of coal liquefaction at the reaction fields, we gave attention to coal particles and coal-derived materials that are hydrogenated and/or carbonized in the liquefaction reactors, and tried evaluation using microscopic technique.On the basis of microscopic textures and optical properties, carbonaceous subst-ances in withdrawing from reactor bottom could be classified into five categories that in-clude vitroplast, mesophase/anisotropic semicoke, non-plastic and partially plastic coal particle, pyrolytic carbon like material and vitrinite remnant, and we clarified its micros-copic compositions. Furthermore, the effects of operating conditions on the properties of carbonaceous substances from the principally reflectance of non-plastic coal particle were researched.Consequently, when the severity of operating conditions was raised, the properties of carbonaceous substances indicated that carbonization was superior to hydrogenation under the atmosphere of initial liquefaction stage. As the reaction proceeds, hydrogena-tion became to predominate over carbonization.At high concentration coal/solvent slurry, we confirmed that hydrogen availability tended to reduce for coal particles. However, we could clear this problem by improve-ment in hydrogen donor ability of recycle solvent.