Patent ID: 6357144
Filing Date: 2002-03-19
Classification: B01D,F26B

Abstract:
A method for drying wood raw material, the method comprising the steps of:supplying wet wood raw material to a first process step; supplying a hot drying gas to the first process step; partly drying the raw material in the first process step; supplying the partly dried raw material to a second process step; supplying a hot drying gas to the second process step; drying the partly dried raw material in the second process step; collecting process gases from the first and second process steps separately; controlling conditions only in one of the first and second process steps so that essentially all volatile organic compounds (VOC) in the raw material are evaporated and concentrated in the process gas collected in said one of the first and second process steps; mixing a hot drying gas with the collected process gas containing the VOC from said one of the first and second process steps; oxidizing the VOC catalytically by heating the mixture to a gas temperature exceeding 180Â° C. to remove the VOC from the mixture; and supplying the mixture that is relieved of the VOC to the other of the first and second process steps as the hot drying gas for the other of the first and second process steps.