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Continuous digester rapid thinning, TAPPI Journal June 2024

ABSTRACT: Carbon steel continuous digesters built after the early 1980s are fully stress relieved, so stress corrosion cracking has been less of a concern. However, these newer digesters were designed to run modified cooking processes that have turned out to be much more corrosive than those running with conventional cooking. This corrosion is mainly associated with softwood digesters and appears to be flow related. Average corrosion rates of 40 mil/year are possible on the exposed shell between the wash and extraction screens. The corrosion patterns are visually distinct from surfaces in the upper digester and below the wash screens. This paper goes into practical detail on where it occurs, the causes, visual identification, inspection planning and results evaluation, and finally, how to mitigate this damage, which consists of applying a corrosion resistant barrier. Some discussion on dealing with general corrosion throughout the digester is included.

Pulp and Paper: Industries with a Bright Future, Paper360º January/February 2019

Pulp and Paper: Industries with a Bright Future, Paper360º January/February 2019

Slave Lake Pulp Generates Biogas, Saves Money, Paper360º November/December 2019

Slave Lake Pulp Generates Biogas, Saves Money, Paper360º November/December 2019

Air and Water Management: Meeting the Ongoing Challenges, Paper360º September/October

Air and Water Management: Meeting the Ongoing Challenges, Paper360º September/October

Online Pulp Dirt Count Analysis: Two Case Studies, Paper360º

Online Pulp Dirt Count Analysis: Two Case Studies, Paper360º March/April 2017

He’s Got the Pulp: Schalka Sets Record as LA CEO of the Year, Paper360º September/October 2019

He’s Got the Pulp: Schalka Sets Record as LA CEO of the Year, Paper360º September/October 2019

IDEAS Digital Twin Technology for Evaporation Plants, Paper360º September/October 2019

IDEAS Digital Twin Technology for Evaporation Plants, Paper360º September/October 2019

Modeling of the energy of a smelt-water explosion in the recovery boiler dissolving tank, TAPPI Journal August 2020

ABSTRACT: The explosion energy generated as molten smelt droplets interact with water was evaluated as a function of smelt distribution, water temperature, and smelt temperature using a thermodynamic model. The results show that increasing smelt-to-water volume ratio and water temperature significantly increases the explosion energy, converting a larger proportion of the thermal energy of smelt into mechanical work. To reduce the chance of violent smelt-water explosions, it is important to: i) optimize the shatter jet design and operation to uniformly distribute the smelt over a large area in the dissolving tank; ii) avoid high green liquor temperature and ensure adequate liquor mixing; and iii) avoid upsets that may cause heavy smelt runoff or jellyroll smelt.

Pixelle Mill in Jay, ME, Jay, ME, Paper360º September/October 2024

Wheat straw as an alternative pulp fiber, TAPPI Journal January 2020

Author: Peter W. Hart | ABSTRACT: The desire to market sustainable packaging materials has led to an interest in the use of various fiber types as a raw material. It has been suggested that the use of annual crops for partial replacement of wood fiber would result in more sustainable products. Several life cycle analyses (LCA) have been performed to evaluate these claims. These LCAs provided conflicting and contradictory results because of the local conditions and the specific pulping processes investigated. Selected LCAs are reviewed and the underlying reasons for these conflicting results are analyzed.