A thesis study submitted in partial fulfillment of the requirements for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1989

The reduction in energy consumption and/or increasing productivity when drying wood, by mean of energy auditing and improving dryer performance, is an important consideration for forest product industry. The studied veneer dryer system is located at Thai Plywood Company, Bangkok, Thailand. Energy auditing was carried out for the hot oil heater and veneer dryer system. Energy analysis showed that fuel cost savings of around 1.32 million Bahts per year, or about 15.9% of the total fuel cost for 1988, was possible by adjusting the A/F ratio and utilizing the flue gas heat recovery system to pre-heat the combustion air. The potential of waste heat recovery system was simulated and evaluated with full-scale dryer system. The option to pre-dry fresh veneer with recovered waste heat was chosen to meet factory objective of increasing plant productivity. Results from laboratory-scale experiment and computer simulation model of parallel flow veneer drying were used as input to simulate the full-scale model of veneer pre-dryer unit. The predicted results were then used for selecting suitable operating conditions for a proposed two-stage veneer dryer (pre-dryer and conventional dryer). As a result, an increase in productivity of kiln no.3 from 36m3 to 67 m3 of veneer solid per day was obtained. Control guideline for the proposed full-scale pre-dryer was also recommended.