Study On Optimum Condition And Energy-saving Of Dehumidification Drying Combined With Conventional Drying For Populus Deltoids Lumber

Wood drying is the most important procedure of wood production. It can guarantee and improve wood quality, reduce degradation loss, increase the utilization ratio of wood. Conventional drying dominant used in artificial wood drying methods. Conventional drying have mature technology, large capacity of kiln, short dry cycle. Meanwhile it also have some advantages, such as high energy consumption, great heat losses, etc. Each kind of drying method has its own advantages and applicable range, combined drying can avoid the disadvantages. Dehumidification drying Combined with conventional drying is the main trend in future, which can improve both energy-saving and drying rate.In this paper, the process parameter optimization of dehumidification drying combined with conventional drying was successfully experiment for the first time of Populus Deltoides drying. The optimizing parameter process conditions of Populus Deltoides combined drying were studied. From initial moisture content to 22% of moisture content,is used by dehumidification drying. In the dry stages, bypass rate of 0.3 is chose for MC from 60% to 40%; bypass rate of 1 for MC from 40% to 30%; bypass rate of 1.82 for MC from 30% to 25%; bypass rate of 2.58 for MC from 25% to 22%. Below 22% of moisture content, is used by conventional drying. In the drying stages, mains frequency of 30Hz is used for MC from 20% to 15%; and mains frequency of 20Hz for Mc below 15%.Populus deltoides lumbers were dried by a conventional, combined drying and process optimization of combined drying method respectively with a same schedule. Results showed that process optimization of combined drying consumed energy of 32.26% less than the conventional drying, of 9.60% less than the without improvement combined drying. Drying time extend only 7.48%. Drying quality have reached grade 2 of national standards. Wood drying can improve both energy-saving and drying efficiency after process parameter optimization, and dehumidification drying combined conventional drying will achieve the optimal energy saving effect.