Fluid dynamics in coal liquefaction reactors using neutron absorption tracer technique

Hydrodynamic properties in the coal liquefaction reactors at the Kaskima pi lot plant, which was constructed based on the NEDOL process, were investiga ted using the neutron absorption tracer technique. The reactor system is co mposed of three vessels, each with 1.0 m ID and 11.8 m in height. The gas v elocity in the reactors under coal liquefaction conditions was estimated us ing a reaction simulator that contained reaction rates and vapor-liquid equ ilibrium. The axial dispersion coefficients in the first and third reactors at superficial gas velocities of 0.06-0.07 m/s were much smaller than thos e reported for air-water systems under ambient conditions. This suggests th at the pilot-plant reactors operated fundamentally in the homogeneous bubbl e flow regime.