PROCESS AND GEAR TO DRY WOOD Russian patent published in 1999 - IPC

FIELD: wood and wood-working industries. SUBSTANCE: invention provides for heating of wood in leak-tight chamber with steam having temperature below that of boiling of moisture contained in wood under pressure above atmospheric one, condensation and removal of extracted moisture, resinous substances and gases. Steam temperature is kept constant, but not above 110 C in the course of time sufficient for removal of resinous substances up to specified threshold concentration. After this steam is replaced in chamber with air under same pressure and temperature 0-10 C below steam temperature and air is emitted out of chamber through adjustable outlets. Process of drying is conducted with constant evaporation rate, air parameters ( temperature, pressure, flow rate and moisture content ) are maintained such that moisture separation is maximal. During transition to drying period with falling evaporation rate all above-mentioned parameters of air are so changed that moisture separation rate in each specified time interval is maximal. Drying is stopped when specified final moisture of wood is achieved. Gear for realization of process has platform to carry pile of wood laid in layers, facilities for condensation and removal of steam and gas atmosphere, facilities for removal of moisture, control facilities, temperature-sensitive elements, pressure transducers, humidity sensors, interface connected to controller, facilities creating and maintaining conditions of maximal rate of extraction of resinous substances, carbon dioxide and methane in process of steam drying and facilities creating and maintaining conditions of maximal moisture separation during drying with air both in period of constant evaporation rate and in period of falling evaporation rate. Complete control package brought outside chamber and including steam generator-humidifier, compressor, flowmeter, heater and controlled valve connected to controller is used in the capacity of facility to maintain maximal rate of extraction of resinous substances, gases and moisture. It also includes analyzers of concentrations of carbon dioxide and methane connected to controller too. Moisture condenser is brought outside the limits of chamber and is manufactured in the form of facility reclaiming harmful substances extracted in process of drying. EFFECT: decreased specific energy consumption, increased quality of treated wood and diminished drying time. 5 cl, 3 dwg