Coal conversion processes. Part I. Liquefaction. R and D report No. 66. Interim report No. 4, August 1973--August 1974. [Reaction kinetics]

Available experimental data on the dissolution of coal into solvent-hydrogen mixtures were analyzed to obtain a mathematical expression for the rate of dissolution. The rate of dissolution was found to depend exponentially on the hydrogen partial pressure and was proportional to the amount of undissolved organic material per unit volume of slurry. The rate was found also to depend on the type of reactor and coal. The low activation energy for coal dissolution appears to indicate that the dissolution may be controlled by the diffusion of some species in the solution phase. The removal of ash from coal-derived liquids by filtration and centrifugation was examined and the economics of the separation has been analyzed in detail for the COED, SRC, and Synthoil processes. In the SRC process the ash separation represented a major portion of the overall fixed capital investment ranging from 23 to 50% for the SRC process. (auth)