Commercial Scale Expanded Bed Hydroprocessing of Solvent Refined Coal (SRC) Extract (Interim Technical Progress Report)

Abstract

The objective of this contract was to demonstrate that solvent refined coal (SRC) extract and expanded bed hydroprocessing (LC-Fining) can be combined to produce a valuable liquid fuel or refinery feedstock from coal. This involved the determination of the optimum process conditions for hydrotreating SRC extract in an LC-Fining process development unit and included engineering studies of the Cities Service Lake Charles LC-Fining Unit. PDU results showed that 60 to 65% of the solvent refined coal is converted to distillates in one pass through two expanded catalyst beds in series. A 30-day catalyst aging run (one batch of catalyst) showed no appreciable catalyst aging at the above conversion level. Sufficient sulfur removal was achieved with a 90+% reduction in the sulfur contained in SRC converted to distillates and an 85% reduction in the sulfur contained in unconverted SRC. The nitrogen removal of 60 to 80% in SRC converted to distillates is insufficient for processing of distillates in other conventional refinery catalytic processes or for direct fuel usage. These require a distillate nitrogen content of less than 0.3 wt %. A 50% SRC/50% foreign solvent blend can easily be handled in the steam tracing and pumping equipment available at Lake Charles. Solvent refined coal can be redissolved in native process solvent, and in selected foreign solvents, without adverse effects, and then can be further processed in an LC-Fining Unit using a commercial catalyst. Coal-derived solvents were more compatible with the SRC than petroleum-based solvents. Conversion, denitrogenation, and oxygen removal in LC-Fining decrease with increasing SRC level in the feed blend and increasing space velocity. Desulfurization was excellent at all levels of the operating variables. There was no apparent catalyst aging effect on conversion, nitrogen, and sulfur removal.