Ainsworth Lumber Co. Project

Location:  Lilloett, British Columbia
                                                                               Year Completed: 1999
                                                                               Deliverables: 14MMBTU/hr
                                                                               two burner installation

Project Overview

The quality of plywood veneer produced in a veneer plant depends not only on the quality of the logs but also on their condition during the peeling process. If the log is too cold, the veneer breaks easily and the yield from a log and the quality of the final plywood decrease. In addition, the lathe knives wear out faster.

To obtain proper peeling condition, the log has to be uniformly preheated down to its core. This is typically achieved in two ways: by immersing the log in hot water in a pond system or by spraying hot water on top of the logs in a conditioning chest system. In a pond system, the log floats for over 24 hours to the other end of the 10'W x 130' long pond. In a chest system, a large door is opened at the end of the chest and the chest is filled with logs. Then the door is closed and a hot water spray system, located along the chest ceiling, is activated.

In both system types, process water is drained by gravity back to the screening and heating system. The heat absorbed by cold logs has to be replenished back into the process water. In cold northern climates, the heat requirement could be as high as 2 to 3 MM BTU/hr per chest with approximately 8 to 10 chests (or ponds) continuously in operation.

The traditional method of process water heating in a veneer plant uses steam injection or an indirect contact immersion type heater.

The Ainsworth Lumber CO. in Lillooet, British Columbia, which recently went through a major modernization, decided to expand the heating capacity of its heating plant to meet new higher production demands.