AN INVESTIGATION OF PRE-IGNITION AIR-FLOW IN FERROUS SINTERING

The Ergun equation was used successfully to model the air flow- pressu re drop characteristics of beds of granulated ferrous sinter feed (a w et deformable particle system). Experiments were performed in a labora tory permeability pot (447 mm high and 130 mm diameter) using sinter f eed blends granulated in a 0.5 m diameter granulation drum. The voidag e and granule size distribution for each bed were carefully measured. 115 beds were tested, made up from 10 widely varying blends and coveri ng moisture contents from 3.5 to 8%. The best values of the constants for the viscous and inertial terms in the Ergun equation were found by non-linear regression to be (k(1)/Phi(2)) = 323 and (k(2)/Phi) = 3.78 , where Phi is the granule shape factor. Using these values, predicted superficial gas velocities agreed with experimental values within +/- 15% for a very wide range of conditions. The original values of k(1) a nd k(2) given by Ergun (150 and 1.75) underestimated the relative cont ribution of inertial losses to the overall pressure drop and were not appropriate for this system. Over the range of variables covered, gran ule size and bed voidage changed significantly with moisture content a nd blend composition. The Ergun equation correctly predicted the effec t of these changes on bed permeability, and hence explained the shape of the permeability-moisture curves for all blends.