Bridging chemical dosage, mixing quality, and variability in paper sheets
2015 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 14, no 5, 311-320 p.Article in journal (Refereed) Published
In the first part of this work, a series of paper production trials were performed on a forming experimental (FEX) pilot machine to investigate the distribution of additives in the final product. In these trials, a blue color was dosed into the stock before the headbox instead of a retention aid. Fine paper sheets were produced using twin-wire forming. Visual inspection of the sheets revealed surprisingly high levels of variability of the blue color. In the second part, the effect of different dosage nozzle configurations on downstream mixing quality of a single-component, polyacrylamide retention aid was studied using two-phase computational fluid dynamics. A non-Newtonian model for this phase was implemented using rheological parameters obtained through a combination of numerical and experimental analysis. Dosage was made into a turbulent pipe flow under typical industrial approach flow conditions. The effect of the number of dosage points, impingement angle, dosage location, and dosage speed on mixing uniformity was investigated qualitatively and quantitatively. Results from these studies indicate the existence of optimal dosage configurations and point toward strong coupling between chemical addition strategy, mixing quality, and chemical variability in final products. Application: Mills can gain valuable information, including dosage nozzle configuration and dosage conditions, for optimizing mixing of retention aids in the approach flow during paper production.
Place, publisher, year, edition, pages
2015. Vol. 14, no 5, 311-320 p.
Chemical bonds, Computational fluid dynamics, Mixing, Nozzles, Paper, Paper products, Papermaking, Turbulent flow, Two phase flow, Chemical variability, Mixing uniformities, Non-Newtonian models, Nozzle configuration, Numerical and experimental analysis, Rheological parameter, Single components, Turbulent pipe flow
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-170290ISI: 000355323600004ScopusID: 2-s2.0-84930366957OAI: oai:DiVA.org:kth-170290DiVA: diva2:832722
QC 201506302015-06-302015-06-292015-08-17Bibliographically approved