Process and apparatus for dewatering low-grade coal

摘要

A process and an apparatus for dewatering low-grade coal, for example brown coal, by steam drying or by hot water drying is carried out in such a manner that brown coal is first comminuted to a particle size of less than about 10 cm and is preheated by steam. The particles are then entrained in a liquid and introduced into a high pressure loader from which they are fed into a high pressure circulation loop and supplied to a liquid/particle separator at the top end of a vertical vessel. The particles entering at the top end of the vessel are contacted with saturated steam or hot water (for example 250-260 DEG C) in counter-current. The particles are finally rinsed in counter-current at the bottom end of a vessel. A slurry of liquid and particles leaving the bottom of the vessel after the rinsing is introduced at a considerably reduced pressure into a second high pressure loader and transferred to a low pressure loop. The liquid and the particles in the low pressure loop are separated and then subjected to an evaporative cooling, in order to result in a dewatered, dry, low-grade coal.