Development of hot blow vacuum drying kiln, 1: Full size dry kiln suitable for production of high quality hardwood lumber
2006
Myojin, M.(Yasujima Co. Ltd., Kanazawa (Japan)) | Yasujima, M. | Hayashi, K.
In order to obtain the higher quality dried lumber of refractory hardwood in shorter drying time , we developed a new drying method with a combination of hot blow and vacuum. It will be expected that the hot blow and vacuum drying method needs the considerably simple operation and lower kiln drying temperature compared with the ordinary drying method, that is, combination of air drying and conventional steam heat drying. At the beginning of development, we tried the experimental tests using a small kiln. The basic data on wood drying under vacuum conditions were accumulated through the tests. In the second step, we carried out the practical kiln run of 5.5 cm thick oak lumber (Quercus crispula) using a full size dry kiln. The thick oak lumber (average initial MC : 61.4 %) could be kiln dried to 8.5 % MC in 55 days under temperature of 27-44 deg C without air drying prior to kiln drying. The quality of the dried lumber was found to be very excellent with negligible defects such as surface checkings, collapse, honeycombing, discoloration, mold and so on.
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