High Speed Drying of Western Softwoods for Exterior Plywood

A laboratory veneer dryer was designed with a tunnel 2 feet wide and 12 feet long, divided into three 4-foot zones. Each zone had an upper and lower plenum equipped with a 80,000 BTV per hour natural gas burner and a blower. The blowers force hot air through vertical nozzles onto the veneer surface as it passes through the tunnel on wire mesh conveyor belts. Drying tests on 1/5 inch strips of Douglas-fir, west coast hemlock, Sitka spruce and balsam veneer, were conducted at 350, 450 and 550?F and 3,000, 5,000, 7,000 and 9,000 feet per minute impinging air velocity. Projected net production of 1/8-inch thick Douglas-fir is 307,000 square feet (3/8-inch basis). This would be achieved with a feed rate of 82.5 fpm and 1 minute drying time. Results are based on drying conditions used. Veneer color, strength, and gluability were not impaired by the relatively high temperatures and circulation rates used or by the short drying times achieved. Results. indicate economies in capital operating and maintenance costs for a single-line production dryer patterned after the experimental model.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member