Simulated combined air-cylinder drying process

In this paper combined air-cylinder drying process is studied using drying simulation model. Combined air-cycled drying process means impingement drying on a cylinder covered with permeable fabric. Paper was dried I single drying cylinder covered with impingement box to see the differences of the drying methods. Focus of the study has been in drying rate improvement compared to the sum of separate processes. Also differences of the temperature profiles during drying are compared and discussed. Results show more than 50% drying rate improvement in combined drying compared to sum of separate processes when dryness is more than 80%. Drying rate is increased to a level of normal impingement drying. Reason for this improvement is enhanced mass transfer from dried paper and lowered paper temperature in drying due to cooling effect of the impingement drying.