Förfarande och anordning för bestämning av fukthalten hos ett finfördelat torkningsmaterial under torkning

摘要

A method and an arrangement for drying material to a predetermined moisture content. The material is stirred or agitated in a drying container and heated by microwave energy while being held at a chosen sub-atmospheric pressure. The magnetrons (1) are switched on and off so as to maintain the material within a chosen narrow temperature range. A continuous mean value (f) is calculated for the quotient ( SIGMA t1)/t2), where (t2) is the time period during which the mean value is calculated and ( SIGMA t1) is the sum of those time periods (t<1>) during which the magnetrons operate at full power within (t2). A threshold value (f0) is established for (f). A time period (t3) during which (f) is at highest equal to the limit value (f<0?) is measured and compared with a predetermined time limit value (t>34<) after (t>3<) has been exceeded (t>3