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Polyvinyl alcohol as foaming agent in foam formed paper, TAPPI JOURNAL August 2019
ABSTRACT: The use of polyvinyl alcohol (PVOH or PVA) as a foaming agent in foam formed paper was investigated. Polyvinyl alcohol is a linear, nonionic water-soluble polymer. It has hydrophobic and hydrophilic parts that give it a surface-active character. PVOH is mainly characterized by degree of hydrolysis and molar mass. Degree of hydrolysis is given as mol-% hydroxyl groups on the polymer. Molar mass is measured indirectly by measuring the viscosity of a 4% PVOH solution. The results show that the degree of hydrolysis of PVOH had a strong effect on the foamability of PVOH. Foamability decreased strongly when the degree of hydrolysis increased from 88 to 98 mol-%. The effect of molar mass on foamability was weaker. We saw an increase in foam stability and bubble size with increasing molar mass, but we did not see any effect on maximum air content. PVOH dosage needed to reach >70% air content (F) varied from 2 g/l up to 10.5 g/l, and the lowest addition levels of PVOH needed were achieved with a low molar mass PVOH with a low degree of hydrolysis. The best strength properties were achieved when using fully hydrolyzed PVOH as the foaming agent. Strength properties (both in- and out-of-plane) of samples made using PVOH were better than those made using an anionic foaming agent (sodium dodecyl sulfate, SDS). By adding PVOH binder fibers to the pulp, we were able to further enhance the strength properties of paper and board.
Journal articles
Magazine articles
On the diagnosis of a fouling condition in a kraft recovery boiler: combining process knowledge and data-based insights, TAPPI Journal March 2023
ABSTRACT: Fouling is still a major challenge for the operation of kraft recovery boilers. This problem is caused by accumulation of ash deposits on the surfaces of heat exchangers in the upper part of the boiler over time. The first consequence is the reduction of steam production due to loss of heat transfer and, finally, the shutdown of the boiler due to clogging. The present work investigated the operational condition of a modern kraft boiler under a critical fouling condition. This boiler had even faced a manual cleaning due to a clogging event. This analysis combined process knowledge, plant team experience, and a data-driven approach, given the complexity of the process. In this sense, historical data covering this critical period of operation were collected. After a cleaning procedure, they were used to obtain a predictive neural network model for the flue gas pressure drop in the boiler bank, which is an indirect measure of ash deposit accumulation. Once validated, it was used for sensitivity analysis, with the aim of quantifying the effects of the model inputs. Five variables out of eighteen accounted for nearly 60% of the total effect on pressure drop. Namely, primary air temperature (21.6% of the total effect) and flow rate (11.1%), black liquor flow rate (9.9%) and temperature (8.4%), and white liquor sulfidity (8.6%). The analysis of these results mainly suggested an excess of carryover, which composes the ash deposits. Recommended actions to mitigate the fouling condition involved adjustments to the primary air system before the more drastic solution of reducing the boiler load.
Journal articles
Editor's Notes: Ready for a Test Drive, TAPPI JOURNAL, Novem
Editor's Notes: Ready for a Test Drive, TAPPI JOURNAL, November, 2006
Magazine articles
Editor's Note: Bright future for coating at ACFS, TAPPI JOUR
Editor's Note: Bright future for coating at ACFS, TAPPI JOURNAL November 2010
Journal articles
Linking Pulp Variations to TMP Operation by Better Selection
Linking Pulp Variations to TMP Operation by Better Selection and Treatment of Process Data
Journal articles
Editor's Notes: Ready for a Test Drive, TAPPI JOURNAL, Novem
Editor's Notes: Ready for a Test Drive, TAPPI JOURNAL, November, 2006
Journal articles
Effect of PCC filler on dewatering of fiber suspension
Effect of PCC filler on dewatering of fiber suspension, TAPPI JOURNAL, November 2006
Journal articles
Magazine articles
Editor's Note: An Ideal Raw Material for Pulp and Paper, TAP
Editor's Note: An Ideal Raw Material for Pulp and Paper, TAPPI JOURNAL March 2010
Magazine articles
Editor's Note: Positive prospects for coated products, TAPPI
Editor's Note: Positive prospects for coated products, TAPPI JOURNAL May 2010
Magazine articles
Editor's Note: Jim Atkins: Technology, training & transition
Editor's Note: Jim Atkins: Technology, training & transition, TAPPI JOURNAL September 2011