Using Simulation to Assess the Performance of a Breakthrough Wood-drying Technology

Conventional wood drying technologies dry enormous batches of lumber bundles. However, they are really inefficient and lack the agility needed to satisfy customers’ expectations. Researchers recently developed a patented precision drying approach that uses a high frequency technology. By building a discrete event simulation model, it has been possible to predict the impacts, benefits and possible constraints of a continuous high frequency drying system. Analyzing simulation results plots, the user can evaluate and compare different designs. Thus, simulation appears to be an important step between the experimentations with the physical prototype of the dryer and the first in-plant implementation. 1 CONTEXT AND PROBLEM DEFINITION In the past few years, the forest-products industry has encountered certain difficulties due principally to economic circumstances. To remain competitive and stay in the race, companies need to lower their costs, diversify their products and increase their quality. In addition to being energy intensive, the wood drying step remains a challenge in terms of quality considering that the specialized value-added products need to be in a precise and narrow range of moisture content. Conventional wood drying technologies typically dry enormous batches of lumber bundles. However, they don’t allow a lot of flexibility in regard to planning and scheduling. This lack of flexibility is linked to using a batch process whose stopping condition is attained when the majority of the pieces are within a specified range of moisture content. Researchers recently developed a patented precision drying approach that uses a high frequency technology for a portion of the drying process. Wood is first dried in a conventional kiln that is shut down prematurely. Each piece of lumber that isn’t yet in the specified range of moisture content is then dried individually using a radio frequency technology. More precisely, the moisture content of each piece is measured at the planer mill. If it is still too high, the piece of lumber is sent to the high frequency electric dryer to continue the drying. This particular process is designed to be continuous and permit certain pieces to be cycled (dried) multiple times depending on their moisture content. On the other hand, the implementation of this mechanism represents a challenge at the operational level: this kind of technology could not be implemented if it were to have a negative effect on productivity and logistic aspects.