Description

ANNOTATION: An alternative to conventional methods of processing small diameter trees for energy use is roll crushing/splitting. The concept involves the crushing and splitting of stems to expedite field drying and to facilitate handling. This method has been considered a feasible alternative for handling stems found in short-rotation harvesting. This paper reports on one of these objectives, the evaluation of roll designs by the Southern Forest Experiment Station for effectively feeding woody Southern biomass into a set of crush rolls. For each of four roll designs, the specific objectives were to determine feeding efficiencies, crushing/ splitting efficiencies, and operating restraints that would allow the greatest range of material site to feed through the primary and secondary rolls. ABSTRACT: Four different roll designs were evaluated on a test bench roll crusher/splitter to determine feeding and crushing efficiencies. For each design, different gap settings for the primary and secondary rolls were tested at two hydraulic cylinder pressures on the primary crush roll to determine their ability to crush and/or feed tree bolts. Seven different diameter classes (1-7 inches) and two southern species loblolly pine (Pinus taeda) and sweetgum (Liquidambar styraciflua), are used for the tests. The results of the test combinations showed that a l/2-inch primary roll gap and a 500-psi cylinder compression pressure, combined with a l-inch secondary roll gap, allowed the greatest range of material to feed through the system. A roll design with a combination of serrated and smooth-angled bars was the best overall feed roll surface. Splitting of the tree bolts had the greatest effect on increasing rate of wood moisture loss.