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Journal articles
Despite the Risks, Asia Presents a Tempting Treat, Solutions!, July 2003, Vol. 86(7)
Despite the risks, Asia presents a tempting treat, Solutions!, July 2003, Vol. 86(7) (310KB)
Journal articles
Spotlight: the Dark ages of pulp and paper education, SOLUTIONS! [03JUNSO08.pdf]
The dark ages of pulp and paper education, Solutions!, June 2003, Vol. 86(6) (76KB)
Journal articles
TISSUE: is the glass half empty or half full, June 2003 SOLUTIONS! [03JUNSO34.pdf]
Tissue: is the glass half empty or half full?, Solutions!, June 2003, Vol. 86(6) (404KB)
Journal articles
Paper Chemistry: Taking Wet-End Chemistry to the Next Level, June 2003 SOLUTIONS! [03JUNSO48.pdf]
Taking wet end chemistry to the next level, Solutions!, June 2003, Vol. 86(6) (334KB)
Journal articles
A loss for us all, Solutions!, March 2003, Vol. 86(3) (72KB)
A loss for us all, Solutions!, March 2003, Vol. 86(3) (72KB)
Journal articles
Containerboard/ Corrugating: the packaging war just got more complicated, MAY 2003 SOLUTIONS! [03MAYSO31.pdf]
The packaging war just got a lot more complicated..., Solutions!, May 2003, Vol. 86(5) (286KB)
Journal articles
Process of Control: Using Process Dynamic Simulation, MAY 2003 SOLUTIONS! [03MAYSO36.pdf]
Using dynamic process simulation for business and risk management, Solutions!, May 2003, Vol. 86(5) (445KB)
Journal articles
SPOTLIGHT ￌ: LONG TERM HOPEFULNESS, SOLUTIONS! January 2006 [05JANSO06.pdf]
Spotlight, Solutions!, January 2005, Vol. 88(1) (53KB)
Journal articles
Magazine articles
Flow rheology of light foams generated from aqueous solutions of polyvinyl alcohol, TAPPI Journal January 2023
ABSTRACT: Recent studies have shown that foam-assisted application of additives into a wet web has advantages over the conventional way of adding the chemicals into the pulp suspension before forming, e.g., increased mechanical retention as well as high dosage giving increased wet strength without impairing the sheet uniformity. To engineer processes utilizing this new technology, the complex flow behavior of applied foams must be quantified. At the minimum, the foam viscosity and the slip velocity at the solid surfaces need to be known to build practical models that can be used in analyzing and upscaling unit processes of the foam-assisted application.In this study, the rheological behavior was quantified for foams having polyvinyl alcohol (PVOH), a widely used strength additive chemical, as the surfactant. The foam density was varied between 100 g/L and 300 g/L, and the concentration of the PVOH solution was varied between 0.5% and 6.0% (w/w). The foams were generated with a commercial foam generator, and the rheological properties of the foams were measured by using a horizontal pipe bank. At the outlet from the generator, the volumetric flow rate, the absolute pressure, and the bubble size distribution of the foam were measured. In the measurement pipe section, the viscous pressure gradient and the slip velocity were measured, after which the foam was discharged to ambient air pressure. The viscosity and the dynamic surface tension of the PVOH solutions were quantified with commercial laboratory devices. In the viscosity analysis, the apparent shear rate was calculated from the volumetric flow rate, and the resulting apparent viscosity was translated to real material viscosity data by applying the Weissenberg-Rabinowitsch correction. The results indicated that PVOH foams can be described with high accuracy as shear-thinning power-law fluids where the detailed behavior depends on the foam density and the PVOH concentration. Slip flow, as usual, increased with increasing wall shear stress, but it was also dependent on the PVOH concentration, the air content, and the bubble size. For both the foam viscosity and the slip flow, a correlation was found that described the quantitative behavior of all the studied foams with good accuracy.
Journal articles
Predictive advisory solutions for chemistry management, control, and optimization, TAPPI Journal March 2025
ABSTRACT: Process runnability and end-product quality in paper and board making are often connected to chemistry. Typically, monitoring of the chemistry status is based on a few laboratory measurements and a limited number of online specific chemistry-related measurements. Therefore, mill personnel do not have real-time transparency of the chemistry related phenomena, which can cause production instability, including deposition, higher chemical consumption, quality issues in the end-product and runnability problems. Machine learning techniques have been used to establish soft sensor models and to detect abnormalities. Furthermore, these soft sensors prove to be most useful when combined with expert-driven interpretation. This study is aimed at utilizing a hybrid solution comprising chemistry and physics models and machine learning models for stabilizing chemistry-related processes in paper and board production. The principal idea is to combine chemistry/physics models and machine learning models in a fashion close to white box modeling. A cornerstone in the approach is to formulate explanations of the findings from the models; that is, to explain in plain text what the findings mean and how operational changes can mitigate the identified risks. The approach has been demonstrated for several different applications, including deposit control in the wet end, both raw water treatment and usage, and wastewater treatment. This approach provides mill personnel with knowledge of identified phenomena and recommendations on how to stabilize chemistry-related processes. Instead of using close to black box machine learning models, a hybrid solution including chemistry/physics models can enhance the performance of artificial intelligence (AI) deployed systems. A successful way of gaining the trust from mill personnel is by creating a plain text explanation of the findings from the hybrid models. The correlation between the likelihood of a phenomena and disturbance and the explanations are derived and validated by application and chemistry and physics experts.