Steady-state thermal behavior of coal liquefaction reactors based on NEDOL process

The direct coal liquefaction plant at Kashima, Japan, was equipped with three reactors, each of which was 1 m in diameter and 11.8 m in length, connected in series. This plant was designed on the basis of the concept of the NEDOL Process, and processed 150 tons of coal per day. The steady-state behavior of the reactors was simulated using an axial dispersion model which took into consideration the liquefaction reactions and the evaporation of oil to the gas phase. The model was validated from axial temperature profiles as well as coal conversion and hydrogen consumption data, obtained from the actual operation of the reactors. The heat of reaction, estimated from the heat balance between the inlet and outlet streams in each reactor, was determined to be 2.1 MJ per I m(3) (STP) of hydrogen consumed. The axial dispersion coefficient of the slurry phase was estimated to be 0.03-0.04 m(2)/s at a superficial gas velocity of 0.06 m/s. The axial dispersion coefficient was smaller and the gas holdup was larger than values reported in previous studies.