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Generalized Steady-State Model for Chlorine Dioxide Brighten

Generalized Steady-State Model for Chlorine Dioxide Brightening of Hardwood Kraft Pulps, 2016 PEERS

Using multistage models to evaluate how pulp washing after the first extraction stage impacts elemental chlorine-free bleach demand, TAPPI Journal November 2018

Using multistage models to evaluate how pulp washing after the first extraction stage impacts elemental chlorine-free bleach demand, TAPPI Journal November 2018

A Roadmap for Reliability Excellence, 2008 Engineering, Pulping and Environmental Conference

A Roadmap for Reliability Excellence, 2008 Engineering, Pulping and Environmental Conference

Use of Urea as an Additive in Kraft Pulping of Eucalyptus, 2008 Engineering, Pulping and Environmental Conference

Use of Urea as an Additive in Kraft Pulping of Eucalyptus, 2008 Engineering, Pulping and Environmental Conference

Toward Deinking of LEP Inks Printed on Different Substrates, PaperCon 2013

Toward Deinking of LEP Inks Printed on Different Substrates, PaperCon 2013

Colloidal Fuel Dispersions using Coal, Petroleum Coke and Asphaltite, 2012 TAPPI PEERS Conference

Colloidal Fuel Dispersions using Coal, Petroleum Coke and Asphaltite, 2012 TAPPI PEERS Conference

Waste Reduction through Recycling Modifiers Design for Recyclability, 14th TAPPI European PLACE Conference

Waste Reduction through Recycling Modifiers Design for Recyclability, 14th TAPPI European PLACE Conference

Preparing prehydrolyzed kraft dissolving pulp via phosphotungstic acid prehydrolysis from grape branches, TAPPI Journal January 2022

ABSTRACT: Dissolving pulp was successful prepared via phosphotungstic acid (PTA) prehydrolysis kraft (PHK) cooking followed by an elementary chlorine-free (ECF) bleaching process from grape branches. The effects of prehydrolysis temperature, reaction time, and PTA concentration that potentially affect the quality of dissolving pulp product on chemical components of pulp were studied via an orthogonal experiment. The structure of lignin was activated during the PTA prehydrolysis phase, and lignin was easily removed during the following cooking process. Thus, relatively mild conditions (140°C, 100 min) can be used in the cooking process. During the prehydrolysis phase, temperature exhibited the most significant influence on the cellulose purity of the obtained pulp fiber, followed by reaction time and PTA concentration. The optimized prehydrolysis conditions were as follows: prehydrolysis temperature, 145°C; reaction time, 75 min; and PTA concentration, 1 wt%. Whether the excessively high prehydrolysis temperature or prolonging the reaction time did not favor the retention of long chain cellulose, the delignification selectivity for the cooking process could not be further improved by excessive PTA loading. Under these prehydrolysis conditions, 94.1% and 29.0% for a-cellulose content and total yield could be achieved after the given cooking and bleaching conditions, respectively. Moreover, the chemical structure and crystal form of cellulose were scarcely changed after PTA prehydrolysis, which could be confirmed by results from Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). PTA prehydrolysis could be considered as an alternative method for preparing PHK dissolving pulp under relatively mild cooking conditions.

Some Preliminary Results on Oxygen Addition to D-Stage Bleaching (D/O), 2022PEERS/IBBC Conference (22PEE/22IBB)

Black liquor evaporator upgrades— life cycle cost analysis, TAPPI Journal March 2021

ABSTRACT: Black liquor evaporation is generally the most energy intensive unit operation in a pulp and paper manufacturing facility. The black liquor evaporators can represent a third or more of the total mill steam usage, followed by the paper machine and digester. Evaporator steam economy is defined as the unit mass of steam required to evaporate a unit mass of water from black liquor (i.e., lb/lb or kg/kg.) The economy is determined by the number of effects in an evaporator train and the system configuration. Older systems use four to six effects, most of which are the long tube vertical rising film type. Newer systems may be designed with seven or even eight effects using falling film and forced circulation crystallization technology for high product solids. The median age of all North American evaporator systems is 44 years. Roughly 25% of the current North American operating systems are 54 years or older. Older systems require more periodic maintenance and have a higher risk of unplanned downtime. Also, older systems have chronic issues with persistent liquor and vapor leaks, shell wall thinning, corrosion, and plugged tubes. Often these issues worsen to the point of requiring rebuild or replacement. When considering the age, technology, and lower efficiency of older systems, a major rebuild or new system may be warranted. The intent of this paper is to review the current state of black liquor evaporator systems in North America and present a basic method for determining whether a major rebuild or new installation is warrant-ed using total life cycle cost analysis (LCCA).