DETERMINING PARAMETERS FOR A RATE OF HEAT TRANSMISSION DURING PAPER DRYING

摘要

Paper drying and the rate of heat transmission are phenomena determined by factors which have not been properly considered in production,thus leading to a significant loss of heat energy during paper production.The paper examines some parameters,showing their influence on heat transmission and exploitation.The drying sieve and its influence on heat transmission and drying rate have been particularly examined.The examination has been directed on the type of sieve weaving,as well as on sieve's tension force and its pressure rate between paper and cylinder.Out of the three types of sieves with various weaving refinements examined,those with highest refinement gave 3 to 4% higher drying rates than the roughest ones.The influence of pressuring paper on the drying cylinder by drying sieve has been tested with a force of 2.2 to 6.6 kN/m~2.Increase of the drying sieve tension to 4 kN/m~2 led to the increase of the heat transmission rate to 3 to 4%.The second parameter examined was the influence of air temperature and speed over the efficiency of tissue paper drying.It was determined that water evaporation may be increased from 90 to 210 kg H_2O/m~2h,and also that the production capacity can be increased for 50 to 70% by the increase of the hot air temperature and speed in the drying box.These examples show how certain parameters influence the transmission rate and how much the efficiency of the drying part can be increased.