FUNDAMENTAL CHARACTERISTICS OF COMBINED IMPINGEMENT AND THROUGH AIR-DRYING OF PAPER

An experimental facility was developed to determine fundamental charac teristics of combined impingement and through air drying of paper. Rem oval of impingement boundary layer humidity by through flow makes both components of the combined process nonadiabatic, complicating the ana lysis. Water removal rate curves for both the impingement exhaust and the through flow exhaust are strikingly different from pure impingemen t and pure through drying rate curves, with the through flow water rem oval rate curve having at times a unique, secondary increasing rate pe riod. Total drying rate is enhanced substantially by removal of a smal l fraction of the drying air as through flow exhaust.