Solvent Deashing Research Articles

Cleaning of coal-derived oils by filtration

With the development of coal liquefaction processes a major task is the removal of solid particles (mineral components, residual insoluble coal and catalyst) from the hydrogenation products. Depending on the characteristics of these products various cleaning methods are under investigation. Thermal methods (distillation, solvent deashing) are preferred for those hydrogenation processes yielding predominantly distillable oils. The separation of solids from the recently developed SRC I processes presents more problems because the percentage of oils is much too low for distillation to be used exclusively for recovering the recycling oil. Therefore, deashing of the SRC I products using solvents within the critical range as well as filtration processes are under development. The Paper describes the different processes under development at the moment and introduces a newly developed candle filter for SRC I filtration. Besides the design of the filter unit, results of filtration tests, handling of the filter cake and production of a filter aid and coke from the residue are described also.