Study On The Intelligent Control System Of Wood Drying

Wood drying is the important section in wood processing, whose quality directly affected the recovery and processing quality of wooden products. Facing the serious shortage of wood resources, drying quality assurance, reduce energy consumption, shorten the drying cycle, reduce environmental pollution, improve productivity, increase the number of high-quality dried wood, whole were necessary to the development of wood drying technology at the present stage.Wood drying is the most energy consumption process in wood processing. In domestic industry of wood drying, conventional drying devices still play a leading role, which takes up 80%. These conventional drying devices have a low drying thermal efficiency about 30~40%. At the same time, most devices are still under manual and semi-automatic control status. Even though automatic control is realized in some devices, the reliability, stability and control precision of its control system and equipment have a great gap comparing to developed countries.According to high energy consumption and serious pollution, a new energy saving and environmental protective wood drying device was designed and manufactured by author who worked as a key technician. Based on conventional drying function, the waste heat recovery, waste gas cleaner and humidity generator were added. Therefore, the system utilized waste heat energy to do secondary work, and the toxic gases such as VOC were carried out cleaning process. Thus, the effects of energy conservation and emission reduction are reached genuinely. Comparing to the conventional drying, 10~15% amount of energy is saved.The controller, suitable for wood drying processing control, used ATmega1280 microcontroller as the core which has 16 digital inputs, 16 digital outputs, 16 analog inputs, 4 analog outputs, 4 PWM outputs, 4 RS232 serial interface vectors and 16M data storage; Based on the varying character of moisture content in wood drying process, real-time moisture content acquisition module was developed which has a measuring range of 6~90% with a precision of±1%; User Interface based on simple MCU control and liquid crystal display touch screen which makes the complex control easier and more reliable.At the same time, the program design and implement of wood drying intelligent control system software was completed. The control system with time benchmark and moisture content benchmark,of two kinds wood drying schedule, would achieved three control methods, which were dry bulb temperature + wet bulb temperature, dry bulb temperature + relative humidity, and dry bulb temperature + equal moisture content. The program of the acquisition of wood moisture content module is designed. The wood drying expert system could provide an optimum solution to common tree species and save the best drying formula. Network topology structures and communication protocol were designed. The real-time and time sharing communication with computer, touch screen and the acquisition of wood moisture content module were implemented by RS232 serial port and RS485 bus.The new wood drying devices and its intelligent control devices are now using in Inner Mongolia Agriculture University and Research Institute of Wood Industry, Chinese Academy of Forestry. Compared to conventional wood drying devices, they have the advantages such as high drying quality, waste heat energy recovery, zero gas emission and reach the affects of energy conservation and emission reduction. As a result, the research achievement plays reference and pushing effects to domestic technical reform and upgrade of wood drying field.