Pulverizing Characteristic of Woody Biomass by a Kind of Impact Mill

Abstract

To investigate the pulverizing characteristic of wood biomass, the dried woody chip and the wood chip with four different moisture content of 5, 10, 15, 20wt% were chose as the raw materials, a kind of impact mill, the universal mill, was used to pulverize the wood biomass at different feed rates, the particle sizes (characteristic particle size and average particle size), uniformity coefficient, density, aspect ratio of wood powder and the specific energy consumption were measured, the pulverizing mechanism was also discussed. The results indicate that the specific energy consumption is in a range from 100 to 400kWh/t, and decreases with the increasing feed rate without changing of the basic motor power; the characteristic particle size is about 625μm, the average particle size is 470μm or so, and both characteristic particle size and average particle size increase with the increasing feed rate, and then decrease before the feed rate reaches to the maximum capacity of the mill; the uniformity coefficient is range from 1.30 to 1.50; the bulk density is about 0.20g/cm, the tap density is about 0.30g/cm, both bulk density and tap density increase with the increase of the feed rate; the aspect ratio is in a range from 2.45 to 2.90 randomly with a common tendency of declining slightly following the increase of feed rate; the pulverizing mechanism of the biomass is the cross section of breakage.