Paper360 - May/June 2013 - (Page 24)

Inside TJ SUMMARIES THE PAPERS SUMMARIZED HERE ARE from the February 2013 Pulp Manufacturing special issue of TAPPI Journal, featuring research from the 2012 TAPPI PEERS Conference, and the March 2013 issue of TAPPI Journal. TAPPI Journal, an online publication of relevant and timely peer-reviewed research delivered via email free to all TAPPI members. To receive TAPPI Journal, join TAPPI at delignification processes that eliminate d hexenuronic acids into the model were h unsuccessful; data were insufficient to u develop a relationship. FEBRUARY DELIGNIFICATION Stoichiometric model of chlorine dioxide delignification of hardwood Kraft pulps with oxidant-reinforced extraction effects Brian N. Brogdon Using published data for various hardwood species, a generalized, steady-state model for hardwoods is proposed for predicting bleaching delignification and/or chlorine dioxide (ClO2) consumption for sequences that use oxidant-reinforced extraction. The kappa number data from these studies were normalized to their respective pre-D0 kappa number, and the normalized kappa numbers were plotted against the bleach demand. Th is mathematical transformation allowed for various brown stocks and oxygen-delignified pulps with different kappa numbers to be modeled as a single curve based on an empirical relationship with fitted equation parameters. One of the two equation parameters could be expressed as simple functions of oxidant-reinforced extraction conditions (i.e., peroxide dosage). The model forecasts ClO2 usage reasonably well (±0.20% ClO2 on pulp) for conventional ClO2 delignification with extraction. Attempts to incorporate modified bleaching 24 Paper360º MAY/JUNE 2013 DISSOLVING PULP DI Implications of converting a Kraft pulp Im mill to a dissolving pulp operation with a hemicellulose extraction stage Enrique Mateos-Espejel, Theodore Radiotis, and Naceur Jemaa The objective of this work was to study the conversion of a Kraft pulp mill to a dissolving pulp operation and the extraction of hemicelluloses from the process. The effects of hemicellulose extraction on mill energy balance, equipment requirements, and new operating conditions were analyzed. Computer simulations of the process and thermal pinch analysis were used. The existing bottlenecks (digesters, lime kiln, and PULP YIELD: Impact of increased digester yield or kappa number on the black liquor higher heated value. recovery boiler) to increasing the dissolving pulp production capacity were identified before and after the conversion. In addition, energy efficiency measures were identified to decrease the energy consumption of the new process. This work will help Kraft mills that envisage a conversion to dissolving pulp operation. The energy, equipment, and operating conditions modifications are shown and an optimal conversion strategy is proposed. PULP YIELD Improving pulp yield for integrated southern hardwood Kraft mills—significance and impact on chemical recovery, steam and power generation, and bleaching John D. Andrews and Peter W. Hart DISSOLVING PULP: Four steps of the optimal strategy for conversion of a Kraft pulp mill into a dissolving pulp operation. As wood is one of the major costs associated with Kraft pulping, it is typically assumed that improving pulp yield or conversely, reducing the amount of wood required to make a specific mass of pulp, is a cost-effective, lucrative endeavor. Although this may be true, it is important to understand the

Table of Contents for the Digital Edition of Paper360 - May/June 2013

Over the Wire . . . News Summary
The 2013 TAPPI Award Winners
Successful Asset Management in the Paper Industry from an OEM Point of View
TAPPI Journal Summaries
Managing the Risk of Fire and Explosion in the Pulp and Paper Industry
Broadening the Availability of Carbon Fibers with Lignin
TAPPISAFE Through the Eyes of a Labor Attorney
Bleached Softwood Kraft Pulp
Association News
What’s New on

Paper360 - May/June 2013