Innovative Dryer and Emission Control System at a Particleboard Installation
In 1989, Bohemia Corporation installed a new primary drying system and also air pollution control equipment at their particleboard plant in Eugene, Oregon. The drying system was composed of a Westec America triple-pass rotary drum dryer fired by a Coen sanderdust burner. The primary and secondary particulate collectors installed were also of a Westec America design. The tertiary air pollution control equipment was a Geoenergy E-Tube Wet electrostatic precipitator.
The Westec dryer internal design demonstrates the benefits of enhanced heat transfer. The two-stage particle collection system incorporates a low pressure drop out box and a multiple cyclone. The collection system removes particles greater than 1.0 microns in diameter with a high collection efficiency. For the solid particles exiting the secondary multiple cyclone, 75% were less than 1.0 micron in diameter.
The Geoenergy® wet electrostatic precipitator is a down flow tube-type precipitator with a patented disk-in-tube electrode geometry. The gas stream is first cooled to adiabatic saturation temperature with recycled water sprays to condense the organic vapors driven off the wood in the drying process. The solid and condensable particulates are collected on the tube walls, washed off, and treated in a recycled water treatment system. Compliance tests for particulate emission showed an average outlet total particulate concentration (solid plus condensable fraction) of 0.009 gr/sdcf. This equates to 2.00 lb/hour of total particulate emissions.