Non-contacting infrared drying: choice of technology

Over the last two years, several large new coated printing paper machines have been built in Scandinavia and Europe. This trend is expected to continue, with at least five more machines scheduled to start-up by the end of 1997. All these new machines have chosen to dry the coated web with electric infrared (IR) technology. Considering the high cost of electricity and the size of these installations, ranging from 10 MW all the way up to 36 MW, this trend is noteworthy. New developments using resistance heated coradiators or reflectors combined with primary IR application on the uncoated side of the sheet, have resulted in major gains in coated sheet quality and production. Also the overall performance in energy transfer efficiency, lamp life, controllability and reliability of electric IR has been dramatically improved. The reasons for choosing a particular type of IR are discussed in this paper, including the differences in the drying process when using either gas or electric infrared dryers.