To design the coal liquefaction reactor of large scale plant in future, it is important to understand characteristics of fluid dynamics in the coal liquefaction reactor. In this study, to measure fluid dynamics of liquid phase in the coal liquefaction reactor operating under coal liquefaction condition, appling of Neutron Attenuating Tracer (NAT) technique was discussed. Distribution of liquid phase residence time could be measured and, mean residence time and mixing diffusivity were obtained.
