The Use of Methanol Vapour for Effective Drying of Cellulose Insulation

The paper deals with a new method of drying cellulose insulation, which uses methanol vapour present in nitrogen as a drying medium. Compared to the insulation drying methods currently used in the industry, the method presented in the article has the following advantages: there is no cellulose depolymerization because there is no need to heat the insulation, there is no need to use large-size and energy-intensive dryers because the whole process takes place in the tank of the transformer. Important parameters of the drying process, such as methanol concentration in the nitrogen, flow rate, and process duration, were determined in four separate experiments. For the purposes of these experiments, a special system was constructed to control and measure the flow of drying medium. Controlling the flow rate of the carrier gas (nitrogen) made it possible to obtain different concentrations of methanol in nitrogen. Such values of concentration and flow rate were determined that allow drying of pressboard and paper in less than 144 h to a level lower than 1%.