Overview of Yankee Resurfacing

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The sound, practical solutions Metso has developed reflect its pioneering role in developing advanced thermal spraying and grinding techniques and its total commitment to quality.

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Metso was the first company to use full face coating as a solution to dryer wear and, over the past 20 years, the company has successfully undertaken more than 100 refurbishment contracts worldwide. This has enabled Metso to offer a maintenance plan designed specifically to suit the "character" of each dryer, ensuring optimum performance and extended dryer life.

Typical problems solved by Metso include:

• Edge wear
• Porosity
• Local damage
• Casting defects
• Uneven heat transfer
• Reduced shell thickness
• Cylinder surface steam leaks

Application of Metso's expertise in grinding, thermal spraying and analytical techniques provides key benefits including:

• Extending dryer life
• Maintaining and improving product quality
• Prevention of breakdowns
• Reducing operating costs
• Savings on long-term maintenance
• Extending re-grind cycles

The treatment of dryers falls into the following key areas:

DIAGNOSIS

Complete operating survey on a Yankee or M.G. dryer using state-of-the-art analysis and diagnostic techniques. Samples of pulp, water and chemicals provide a complete insight into the condition of the dryer, its ability to produce paper and the need, if any, for remedial action. Investigations using unique thermal imaging techniques originally developed for the aerospace industry will pinpoint potential troublespots on an otherwise serviceable dryer. Metso will carry out tests either on site or in its own headquarters test facility.

FORECASTING

By analyzing the information gathered, Metso can detect early warnings of any potential problems, thus preventing unscheduled shutdowns. Survey results can also eliminate the dryer as a problem area.

ACTION PLAN

At the conclusion of each investigation, Metso will advise on the operational life of the cylinder and the optimum time for treatment, whether a brief shutdown to prevent further deterioration of a small problem, or a complete refurbishment. What's more, Metso will recommend the best way to approach the problem so that the dryer is not only reinstated, but also capable of improving product quality.