SPRAY DRYING METHOD AND APPARATUS AND CLEANING METHOD FOR SUCH AN APPARATUS

摘要

In fluidized spray drying of a feedstock to produce an agglomerate product by means of at least one spraying device (7) arranged in the upper part (2) of a vertically disposed drying chamber (1), in a lower part of which a fluid-bed is accommodated, a drying gas introduced into a processing zone (16) of the chamber (1) is exhausted through an integrated arrangement of filter elements (11) in the upper chamber part (2) to retain and allow agglomerationof the particles carried by the flow of drying gas on the filter elements (11). By intermittent supply of reverse flow gas pulses to the filter elements (11) the retained particles are released and returned to agglomeration zones (16, 17). The drying gas is introduced at a rate producing at the filter walls (13) a flow rate amounting to at least 150 cubic meters per hour per square meter of filter wall surface. In the non-operative condition of the spray drying apparatus the filter elements (11) may be cleaned-in-place by supplying a cleaning liquid to the interior of the elements.