METHOD OF PERMANENT HUMIDITY CONTROL OF TIMBER IN DRYING CHAMBER Russian patent published in 2017 - IPC G01N33/46 

FIELD: heating; drying.

SUBSTANCE: piled timber on a pile cart with strain gauges is placed into a hermetical drying chamber between electrodes connected to a high-frequency generator. The gauges are connected to a weight measuring system. Values of the set parameters of timber and required residual pressure are input into a computing unit. Before vacuuming, the initial pressure in the chamber is measured, then, a vacuum pump is turned on and the mass of removed air is measured. After reaching the required residual pressure, the pump is turned off and the temperature and humidity of the medium are measured. Following the measured magnitudes, the computing unit defines the volume of timber at the bone-dry humidity. After that, the high-frequency generator is turned on and the process of drying is intensified by means of the dielectric heating of timber. During the process of drying, the current pile mass is measured constantly or frequently and the current humidity of timber is defined. Before the loading into the chamber, samples are taken from the pile; these samples are used for definition of properties of timber according to the prescribed standards; the pile is stored on the premises, where the chamber is installed, at the temperature of 10-20°C and relative air humidity of 70-90%. Directly before the loading, the initial humidity is measured, and after the loading, the previously measured properties of timber, values of the initial humidity and required residual pressure are input into the computing unit. Whereupon, the pressure inside the chamber is reduced down to 8-10 kPa and the dielectric heating is performed reaching the temperature of 45-60°C, which is kept constant by means of adjusting of the power of the high-frequency generator during the entire process of drying.

EFFECT: increasing of measurement accuracy of the current humidity of timber, as well as increasing of effectiveness of humidity control during the process of drying.

1 dwg