METHOD OF TIMBER DRYING AND ASSOCIATED DEVICE Russian patent published in 2008 - IPC F26B5/04 F26B9/06 

FIELD: heating.

SUBSTANCE: invention is referred to construction industry and wood processing industry, particularly to fast drying technologies of wood including large-size timber by equipment generating strong vacuum pulses in cyclic mode due to volumetric proportions of drying and vacuum chambers and vacuum depression in drying chamber by vacuum pump. Timber drying method includes transportation and storage operations by means of trolleys, process operations in two operating chambers with the 30-minute operation interval, heating, agent movement and distribution, stacked drying by means of hot air generators, reverse fans and flow splitters, softening and moisture balancing along timber cross section by hot water and moistening system steam with further curing during heating at atmospheric pressure or residual vacuum. After that, steam and air mixture is removed from operating into vacuum chamber by cyclic vacuum pulses at power corresponding to their volumetric proportions and further vacuum depression in time by vacuum pump. Process is controlled by proper devices by pressure, temperature and humidity. In addition, transportation and storage operations are performed by means of transverse and share trolleys at different elevations. They are equipped with clamping able to take up springs. Heating within 80-140°C is performed and agent is moved at 3.5-4 m/sec through diffusion channels. Each channel is symmetrical to two lines of stacks. Moistening is conducted by water or steam at temperature from 65 to 115°C with further curing within 20-150 min. Steam-air mixture is removed from operating chambers and moisture is removed from timber at final pressure in vacuum chamber being within 2-60 mm m.c. Besides, to removed free and bound moisture, timber temperature is selected within 65-85°C and 80-95°C. Rarefaction is created in operating chamber to 80-120 and 30-100 mm of m.c., avoiding moisture decrease at surface with regard to middle part of timber cross section W=15-25% and W=5-15%. Besides, each pair of electrodes with double insulation, moisture-metering devices are inserted into timber with lancet-shaped end, in at least, two points at 10÷15 mm depth from surface and middle part of cross section. Drying unit contains trolleys with clamping for stacking, access ways and rope hoisting, two operating chambers equipped with vacuum valves, hot air generators, reverse fans and flow splitters interrelated with vacuum and pneumatic systems, moistening system, monitoring system and drying control system by means of pipelines and valves. Besides, hot air generators and fans are compactly located in trapezoidal upper part of each operating chamber in diffusion channels. Channels are made in sidewalls in symmetrical plane to each two lines of padding. Their cross section is gradually increased towards side walls of chambers. Drying agent is removed with moisture and through channels connected with nozzles located between diffusion channels and in symmetrical position to stack. It is removed at vacuum pulse generated by volumetric proportions between operating and vacuum chamber such as 1 to 1.2-1.8 with further vacuuming by vacuum pump but depending on timber type and within 5 to 65 minutes. It is done through pipelines and valves where actuators operate at 400-800 mm/sec speed with conditional passages selected within 45 to 50 mm per 1 cubic meter of operating chamber. Invention has to ensure high quality drying of boards and cants at minimum volumetric proportions between drying and vacuum chambers and heating interval with regard to vacuuming interval.

EFFECT: effective drying of timber.

3 cl, 8 dwg