Testing of a counter-flow, stack-type sawdust dryer

Abstract

The objective of this research was to test a prototype sawdust dryer designed by Arrowhead Forest Products, a wood products firm based in St. Louis. The dryer is designed to be used by small to medium sized sawmills and pallet mills.

A series of 50 one hour or longer trials were conducted to develop operating parameters and test the sensitivity of the dryer performance to species, operating speed, throughput rate and Xi atmospheric conditions. Performance criteria measured included moisture content removed, final moisture content and pounds of water removed per hour in the entire system and the individual system components. Performance measures were developed from 30 one kilogram sawdust samples collected during each trial. The sampling procedure paired samples pulled with temperature profiles across the dryer and ambient weather conditions. Analysis of variance and analysis of covariance were used to explore relationships and interactions between the variables of interest.

The system proved capable of removing 10% to over 60% of the initial moisture in the sawdust. The amount of drying that occurred was dependant on the throughput rate of sawdust. The overall energy efficiency of the system was approximately 60%.