SOLVENT REFINING FOR CLEAN COAL COMBUSTION.

Solvent refining removes sulfur and particulates from coal by the use of hydrogen in a reaction system at elevated temperature and pressure. In this process, a substantial portion of the coal is dissolved by an internally generated solvent. Particulates are removed by filtration or other methods. About 70% of the sulfur is converted to hydrogen sulfide and filterable iron sulfides. The end product, a liquid under reaction process conditions, is cooled to an essentially ash-free solid of reduced sulfur content that is useful as a fuel for power generation. Solvent-refined coal (SRC) is of particular interest to electric utilities as a way to extend coal-fired plant life, even while meeting newly lowered limits for sulfur emissions. As development continues on process equipment and controls, two pilot plants are successfully refining several U. S. coals to meet EPA sulfur specifications. Equally important is finding the best way for utilities to pulverize and burn SRC.