Programmable Control for Lumber Drying in Chambers

A programmable control system for the convective drying of lumber in chambers is developed, based on specially designed drying algorithm, which allows computing the set-point values for the temperature and the relative humidity of the heating and drying air as a function of the wood type, wood thickness and the current average value for the wood moisture content and wood temperature. The special three channel measuring instrument ensures reliable and correct on line wood moisture measurement results for the correct set points calculation of the main controller in different working regimes. This individualization of the drying regimes according to the parameters of each consignment of different materials ensures optimization of the quality and minimization of the energy costs of the whole process. Besides, the implementation of the developed control system proves its high reliability. It is not only cheaper but also easier to tune service and apply in small woodworking companies.