The in-woods cleaning of whole-tree-chips

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Virginia Polytechnic Institute and State University

This research examined Whole-Tree-Chip cleaning methods applicable to field operations in Pinus taeda L. (Loblolly pine) on the coastal plain of South Carolina. Objectives were: 1) to examine current and potential cleaning methods, and 2) develop and test two cleaning approaches suggested by past research.

An open top chip van was modified to: a) determine the dispersion and composition of whole-tree-chip fractions by the installation of sampling buckets and floor pans and b) provide a platform for testing two cleaning systems. System one consisted of anti-clogging screens which pre-screened chips as they were discharged at the mill. It also allowed floor pans to sample the load for fines. System two utilized a radial blade blower which altered chip stream composition during loading by the Whole-Tree-Chipper.

Eight trials were conducted over a six month period using a Morbark 22 chipper. Results indicated floor screens could have been more effectively positioned at the chip dump. As installed, and pin they successfully removed 1% of the load in fines chips. The best chip stream treatment involved double deflection: first from a vacuum assisted primary screen located in the van roof, and then from a passive screen located below and behind the first. This design reduced bark and fines by one-third.