⑴Conventional drying method: The conventional drying method is a convection heating drying method in which hot and humid air is used as a drying medium. It has many structural forms and is a method of drying wood used in wood processing enterprises. There are many heating methods (which can be divided into conventional steam, hot water drying and conventional furnace gas drying); the range of loading volume varies widely (small is several cubic meters, and large is several hundred cubic meters), which can meet Various production needs; the drying process is easy to master and control. As analyzed in the previous chapter, most mahogany products manufacturing companies have small annual wood processing volume, mixed tree species, and large changes in board specifications. Therefore, kiln bodies with a volume of about 15 to 25 m3 are selected. For the steam and hot water kiln, it is better to choose an overhead fan. The air circulation in the small kiln stack is more uniform, and the difference in temperature and humidity is small, which can meet the production needs and achieve better drying quality.
⑵Vacuum drying method: Vacuum drying method is also widely used at home and abroad. The vacuum kiln body is a cylindrical metal structure, which has good pressure resistance and tightness. The drying principle is to use the degree of vacuum in the tank to reduce the boiling point of water and accelerate the speed of moisture in the wood, thereby increasing the drying speed and shortening the drying time. Therefore, when the vacuum drying method is selected, the drying temperature is low, which can reduce or avoid drying defects such as internal cracking and shrinkage of the wood. The vacuum drying method is more suitable for drying hard hardwood thick boards, and it has a good drying effect on hardwood with good permeability.
(3) Air-drying and conventional combined drying: Air-drying is atmospheric drying, which has low drying cost. The correct air-drying is not easy to cause drying quality problems during the high moisture content drying stage of the wood, and the drying speed is acceptable. When the rate is lower than the fiber saturation point (FSP), the drying speed is too slow. If the air-dried semi-dry material is dried by conventional drying method, the kiln drying time can be shortened significantly. The air-dried wood board surface is very flat and will not cause defects such as surface hardening, honeycomb cracking and shrinkage. Air-drying and conventional combined drying are also effective methods to improve the drying quality and reduce the drying cost of wood. Air drying is easy to implement. After the air-drying is completed, the wood is loaded into a conventional drying kiln, which can greatly improve the work efficiency, save time, reduce costs, and obtain better economic benefits. The use of wood: It should be divided into direct use and chemical or special processing as raw materials. Wood is directly used in: construction, pit wood, electric poles, sleepers, packaging, furniture, craft carving, ships, sports equipment, cultural and educational supplies, musical instruments, decoration, wood-based panels, etc. After chemical processing or special processing, the raw materials used are: papermaking, rayon, regenerated cellulose, nitrocellulose, cellulose acetate, ethyl cellulose, hydroxy cellulose, and phenyl cellulose.