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Keeping those rollers clean

The new Pineline PolyPro chemical protection method developed by Tekno-Forest is designed to deal with a common problem affecting paper machines running thermomechanical pulp: the unwanted adhesion of extractives to roller surfaces. Eliminate this and you can eliminate many web breaks and quality problems, and improve runnability.

The benefits offered by Pineline PolyPro are based on a protective coating that binds very effectively to roller surfaces and shrugs off contaminants, making for smoother web throughput and reducing the frequency of web breaks. The coating binds contaminants electrostatically, enabling them to be easily flushed away as part of the normal production process.

Pineline PolyPro solutions are always tailored to the specific chemistry of the paper machine they are intended for – recognising the fact that, however similar they may be in many respects, every machine and every mill is different.

Good results

Building on an existing line of cleaning agents for the paper and process industries, the ‘inspiration’ for Pineline PolyPro came from problems that one of Stora Enso’s mills was having from time to time with build-ups of contaminants on the rollers of its press sections. Analysis showed that the deposits in question contained a mix of pitch, fillers, and fine fibres.

Tekno-Forest took the problem in hand and developed a protective chemical that could be dosed on the rollers together with normal wash water. The product solved the problem and enabled the mill to eliminate contamination virtually 100% and achieve significantly lower numbers of web breaks.

Since those first trials, the solution has been further developed. The biggest step forward has been the elimination of the need for trials on a customer’s machine. Today, these can be handled with simulation software using field data, such as the key parameters of a machine’s white water and roller surfaces, and laboratory tests to establish the precise chemistry called for.

No extra wastewater load

Unlike traditional solutions that use polymers dosed into pulp to bind contaminants, Pineline PolyPro is designed to eliminate extractive-type contaminants altogether.

In addition to thermomechanical pulp (TMP), Pineline PolyPro technology is also suitable for use with recycled fibre, which often contains sizing agents and ‘stickies’ that can easily attach themselves to machine surfaces.

The fact that Pineline PolyPro’s constituents do not change the properties of the paper web and do not add to a mill’s wastewater loading is particularly valuable in today’s world, where deposits are becoming a growing problem as a result of dramatically reduced water usage per tonne of output and higher machine speeds.

One of the most critical parts of the papermaking process when using TMP is the central roller of the press section, where the web comes into contact with the machine’s rollers for the first time – and where Pineline PolyPro works its ‘magic’.

> Esa Mäkinen
(Published in HighTech Finland 2009)