Various Root Causes of Buildup on Paper Machine Dryer Cans
In part 1 of this topic, we discussed the various root cause of buildup on paper machine dryer cans that lead to increased steam usage, poor temperature and moisture profiles, more sheet breaks, and other process issues.
We also discussed the use of Fluoron’s BCS roller cleaning service to quickly remove contaminants from dryer cans once buildup has occurred. In part 2 of this topic, we will look into approaches for reducing or completely preventing buildup on dryer cylinders in the first place.
In the quest to reduce buildup on roller surfaces, some paper mills include adding detakifying agents such as talc in the processing solution to help reduce the stickiness of the fibers, gums, and glues in the pulp. Other operators utilize retention aids which attempt to keep tacky materials incorporated into the sheet such that they don’t precipitate out onto the process equipment. While these chemical solutions can often slow down the rates of buildup, they are also often costly to implement and maintain and can lead to other processing issues further downstream. Fluoron has worked to solve this problem by offering a number of advanced solutions that prevent buildup and prevent corrosion and damage to dryer cylinders and other rollers.
On Machine Seamed FEP for Non-Doctored Dryer Cylinders
For dryer cans without doctor blades, Fluoron’s On Machine Seaming (OMS) technology allows our technicians to install a non-stick high release sleeve directly onto the dryer can surface in place during a short mechanical outage.
Fluoron was the original inventor of on-machine seaming technology and installed the first OMS sleeve in 1969 at the Riegel Paper mill in Milford, N.J. Over the years, this technology has enabled hundreds of paper machine operators to improve their process operations by preventing buildup on their dryer cans.
The OMS heat shrinkable sleeve is made from FEP fluoropolymer and is fabricated by Fluoron’s unique seaming process. The sleeve is expanded at Fluoron’s facility before being shipped to the mill location. Once onsite, Fluoron technicians wrap the sleeve around the dryer can seam the sleeve in place into a continuous tube of FEP, and finally, heat shrink the sleeve down around the dryer can. Adhesive bonding is used underneath the sleeve to attach it to the roller surface and provides a long-lasting non-stick solution that prevents buildup and is easy to clean.
PTFE for Non-Doctored Dryer Cylinders
Another alternative for non-doctored dyer cans is Fluoron’s X550 Fluoropolymer spray-on coating of PTFE. Prior to installing the coating, Fluoron’s BCS cleaning system is utilized to prep the roller surface and remove any contaminants and buildup. Fluoron technicians will then spray coat the PTFE coating directly on the dryer cylinder as it is slowly rotated. Once the coating is complete, internal steam is turned on and the coating is cured at maximum dryer can temperature.
This durable coating has been known to last upwards of 5 years in several paper mill dryer can applications providing an excellent release for starch and paper fiber buildup.
Fluor-XR for Doctored Dryer Cylinders
As many modern paper machines utilize doctor blades either continuously or periodically to remove recycle stickies and fiber buildup from their dryer cans, Fluoron engineers launched a three-year research program to develop a robust coating that would withstand intermittent and continuous doctor blade usage.
The end result was the Fluor-XR tungsten carbide reinforced release coating that can withstand severe abrasion as the release coating is protected within a matrix of tungsten carbide particles.
To install this coating, the dryer can surface is first grit blasted to remove any buildup. This is followed by a plasma spray of tungsten carbide particles that provide the reinforced layer on the dryer cylinder.
Finally, a topcoat of Fluoron’s proprietary extreme release coating is applied which embeds itself within the tungsten carbide matrix, providing a robust, wear-resistant, extreme release system that can withstand years of prolonged abrasion without losing its release characteristics.
While it is often a challenge for paper machine operators to keep their dryer cans running clean, the benefits can be significant. Contact us today to discuss your particular issues and see how Fluoron can improve your process operations.