Preliminary evaluation of chemical coal cleaning by promoted oxydesulfurization

Abstract

Atlantic Richfield Company has developed several proprietary process configurations for the chemical cleaning of coal. Two of the configurations incorporating promoted oxydesulfurization were selected for technical and economic evaluation. A One-Step Process utilizing relatively mild process conditions and a Two-Step Process including an additional higher severity reaction step were evaluated using a one-gallon batch reactor. Nearly all of the pyritic sulfur as well as up to 94% of the iron and 50% of the ash were removed by the One-Step Process. The Two-Step Process removed up to 35% of what is generally reported as organic sulfur. For both processes, 95% or more of the Btu value of the feed coal was recovered as product. A pilot plant employing a two-liter, continuous reaction system was constructed and operated. Initial results indicate sulfur removal efficiencies somewhat higher than predicted from first order reaction kinetics developed from the batch reactor data. Although engineering studies initially indicated an economic advantage for the reactor section, the cost of recovering the chemical reaction promoter more than off-set the reduced reactor section cost. Process alternatives incorporating both chemical and physical modifications to reduce costs are being evaluated.

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