THE BEHAVIOR OF L-VALVES WITH GRANULAR POWDERS

An extensive experimental program was carried out on three sands, all group B powders, in L-valves of diameter 40, 70 and 100 mm. The radius of the elbow, the number of aeration points and the inclination of the horizontal section influence the solids flow rate. In a system in which both the feed hopper and the discharging solids are at atmospheric pressure, the maximum solids fluxes achievable can be calculated from hopper discharge correlations and are in the range 600-1200 kg/(m2 . s). The minimum aeration gas requirement is determined by the incipient fluidization velocity of the powder. Correlations are given from which the aeration gas flow rate and the pressure drop across the L-valve can be calculated for any solids flux, and a design procedure is given for systems using group B solids.