Advanced Control of Hydrophobic Contaminants in the Paper Machine Wet End, PaperCon '09 Conference

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The increased use of secondary fiber, coated broke and mechanical pulp in the papermaking process contributes to the accumulation of organic contaminants. These contaminants can form deposits that affect machine runnability and final product quality. Control of the contaminants is typically managed through chemical fixation, and its effectiveness is therefore dependent on the ability to determine the proper program and application. Historically, a common method used to assess program performance has been filtrate turbidity reduction. This method, however, is not entirely adequate because it often yields an incomplete picture of the furnish demands from hydrophobic particles. More recently, flow cytometry has been used in the industry for monitoring hydrophobic contaminants. Disadvantages of this method are that it is both labor and capital intensive. Nalco Company recently developed a fluorescence technique to monitor the relative concentration of hydrophobic materials throughout the paper machine wet end. This technique, which is both easy to use and inexpensive, can also act as a screening tool for contaminant treatments in order to evaluate efficacy and dosage. Results of machine surveys and the impact of contaminant control agents will be discussed in this paper.