Pressurised steam drying of Australian low-rank coals - Part 1. Equilibrium moisture contents

Pressurised steam drying of two La Trobe Valley coals (Loy Yang and Morwell) and a South Australian Bowmans coal has been studied using steam pressures of 1 and 2.5 MPa in the temperature range 180-260 degrees C in a batch laboratory scale autoclave. The degree of moisture removal as a function of both temperature and superheat has been studied. The steam equilibrium moisture content of the coals was related to the degree of superheat by a simple equation. The relationships between drying conditions, the properties of the steam-dried coal and the amount of organic material released into the condensate have been established. The release of organic material only became significant when a major portion of the water had already been removed. Surprisingly, the organic material which could be extracted into methylene chloride was found to consist almost entirely of a mixture of phenol and methoxyphenols. (C) 1998 Elsevier Science B.V. All rights reserved.