SYSTEM FOR DRYING PARTICULATE MATERIALS

摘要

Abstract The specification discloses a system for drying a feed material in a particulate form such as brown coal, the system including: (a) a dryer through which the particulate material is passed 5 and including: (i) a fluidised bed section having at least one heat exchanger supplied with heating fluid at a temperature above 100'C, and (ii) a non-fluidised section downstream of the fluidised bed section to which the particulate material from the fluidised bed section passes, the non-fluidised section having at least one associated heat exchanger to further heat or to maintain heat within the particulate material passing therethrough, whereby the particulate feed material is o partially dried within the fluidised bed section and is subsequently further dried within the non fluidised section, (b) a feeding system for feeding the feed material in particulate form to the dryer at a controlled feed rate, and (c) a discharge system through which the particulate material emerging from the non-fluidised section is passed from the dryer. The heat exchangers of the fluidised bed section and of the non-fluidised section are supplied with heated gas at a 5 temperature of greater than 100'C, the heated gas preferably being superheated or saturated steam. A particle loosening system is in the non-fluidised section to promote continual flow of particulate material therethrough, the particle loosening system including gas distributors located beneath the non-fluidised section whereby intermittent supply of pressurised gas (e.g. superheated or saturated steam or nitrogen or inert gas) therethrough loosens particulate material 0 in the overlying non-fluidised section. The particulate brown coal passing from the fluidised bed section to the non-fluidised section has a water content of about 9% to 18% by weight at or near its critical water content (e.g. no more than 20% above and no less than 20% below the critical water content), and when passing from the non fluidised section has a water content of about 3% to 7% by weight. < 00 H o~ LUj - 00 CV'H Lf.) (0 0 0 Co