These requirements kilns include requirements for aerodynamics: The kilns should be provided with a uniform velocity of air circulation in the material. The speed depends on the species and thickness dried boards. Charles Schwab Corporation is often quoted as being for or against this. For the thin planks of wood fast drying rocks efficient high-speed air flow (2.0-2.5 m / s). For thick boards, and drying is particularly difficult to breed, the speed may be reduced in two times without performance degradation kilns (the same quality at the same time will be higher than at a high rate of circulation). Thus, the efficient conduct of the drying process must be able to controlling the speed of air circulation, at least 2 speed motor. Note that low speed is required when drying fast drying wood (drying from 18 to 20% and final moisture content).
If the kilns are not provides regulation of air, to manage this process by using gaskets. However, this will inevitably lead to poor performance by 10-15%. Requirements for fencing: – Fences should be tight. – Have a strong internal moisture barrier. – Have the best thermal protection for the heat transfer coefficient of 0.3-0.4 W/m2 at least 0C.
This requirement stems from not only saves heat energy but also the need to maintain the drying mode. Requirements for thermal equipment: – drying chamber should have sufficient thermal capacity, providing lift and maintain the temperature at a given level. – Heaters should be made of stainless steel materials. Requirements for ventilation of chambers: – Ventilation chamber should provide a stable supply air parameters in both summer and winter (air should flow into the chamber, having a positive temperature). This is achieved through the use of cameras in the recovery systems, air parameters – energy recovery. When using the camera without energy recovery in the winter time, productivity is reduced by 20-40%. The reason – incoming cold air is not only condenses the moisture (that is the reason for the increase of drying time in the first stage), but also negatively affects the quality of the drying process. If the use of recuperators for some reason impossible, to organize the chamber forced exhaust the exhaust air, and to organize the inflow from the premises. Requirements for monitoring and controlling the process: – Cameras need to be provided psychrometric system climate control. It should be noted that the system shows the worst results UGL – control of temperature and equilibrium moisture content of wood, which are equipped with many imported dryers. Research have shown that the adequacy of indications of this system is worse than a psychrometric. This means that violate the drying and, consequently, affects the quality of dried lumber. – The cameras must be equipped with control system of the current moisture content of wood as a common division of the drying process with respect to time gives the worst results. – Managing the process should be automatic. In Finally, we note that the Department of Technology woodworking industries have much experience of reconstruction and development projects of new kilns, the examination of imported equipment, improve technology and organization of the drying plants, which can be very useful for producers.