CASE STUDY: How to solve build up on dryer cans to save energy and cull tonnage
Reprinted from PULP & PAPER CANADA 1/7/07
Build up on dryer cans is a costly problem in the paper industry. Just how costly? One paper machine supervisor at a mill on the west coast reported after cleaning the pitch from their dryer cans, "We achieved approximately an 80% decrease in lost time due to ink related breaks. We also decreased our steam consumption by 40-50% and decreased the cull tonnage by approximately 70-90%." He said the dryer can cleaning was, "essential to increasing our productivity. Fluoron did an excellent job on cleaning and polishing the cans."
The dryer cleaning was done by Fluoron Inc., Elkton, MD, who has multiple crews and machines to remove all kinds of "pitch" problems. They not only clean the dryer cans, they also apply release coatings on the cans to keep them clean.
What is "pitch"? White pitch consists mostly of cellulose, latex binders, fillers and wood resins. Pitch can be a variety of naturally occurring hydrophobic, organic resins of low and medium molecular weight. Pitch includes fatty acids, their insoluble salts, and esters of the fatty acids with glycerol and sterols, as well as other fats and waxes. These compounds display characteristic degrees of temperature-dependent viscosity, tackiness and cohesive strength. They may deposit alone or with insoluble inorganic salts, fillers, fibers, defoamer components, and all other papermaking chemicals including coating binders.
White pitch is a common form of sticky. With advances in the paper industry, there is a new breed of "pitch-like" stickies. Stickies became a bigger problem with the development of many de-inking systems, higher use of recycled fiber and closing up machine systems to satisfy environmental pressures.
Stickies are generally composed of complex polymeric materials. They originate from a variety of sources: synthetic adhesives, hot melt and pressure sensitive, rosin and synthetic sizing agents, binders, wet and dry strength resins and all other types of papermaking chemicals formed during the papermaking process.
All of these stickies are easily removed, restoring the dryer can's surface with Fluoron's cleaning system. Then, they can apply a "Fluoro-Coat" release coating to prevent build up on the roll in the future.