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Journal articles
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Open Access
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).

Journal articles
Magazine articles
Open Access
Editorial: Research, conferences, and COVID-19, TAPPI Journal May 2021

ABSTRACT: While medical science in fields like virology blazed a path in 2020 in developing vaccines, diagnostic tests, and treatments to combat the COVID-19 pandemic, other scientific research slowed significantly.

Journal articles
Magazine articles
Open Access
Impact and feasibility of a membrane pre-concentration step in kraft recovery, TAPPI Journal May 2021

ABSTRACT: Emerging robust membrane systems can perform the first section of black liquor (BL) concentration by separating clean water from the black liquor stream using only mechanical pressure. By doing so, they can reduce the steam and energy required for BL concentration. Because of the high osmotic pressure of strong BL, a membrane system would not replace evaporators but would operate in series, performing the first section of BL concentration. In this work, we use a multi-effect evaporator (MEE) model to quantify the steam and energy savings associated with installing membrane systems of different sizes. When maintaining a constant BL solids throughput, we find that a pulp mill could reduce steam usage in its evaporators by up to 65%. Alternatively, a membrane system could also serve to increase BL throughput of the recovery train. We find that a membrane system capable of concentrating BL to 25% could double the BL solids throughput of a mill’s evaporators at the same steam usage. We also demonstrate that installing a membrane system before an MEE would minimally affect key operating parameters such as steam pressures and BL solids concentrations in each effect. This indicates that installing a membrane pre-concentration system would be nonintrusive to a mill’s operations.

Journal articles
Open Access
Abitibi consolidated's mill in snowflake, az, converts to 100% recycling, TAPPI JOURNAL, April 2000, Vol. 83(4)

Abitibi consolidated's mill in snowflake, az, converts to 100% recycling, TAPPI JOURNAL, April 2000, Vol. 83(4)

Journal articles
Open Access
A six-year review of the TAPPI research funding program, TAPPI JOURNAL, April 2000, Vol. 83(4)

A six-year review of the TAPPI research funding program, TAPPI JOURNAL, April 2000, Vol. 83(4)

Journal articles
Open Access
Aerodynamic characterization of dryer fabrics in a wind tunnel, TAPPI JOURNAL, April 2000, Vol. 83(4)

Aerodynamic characterization of dryer fabrics in a wind tunnel, TAPPI JOURNAL, April 2000, Vol. 83(4)

Journal articles
Open Access
Performance evaluation of two simple causticizing control systems, TAPPI JOURNAL, April 2000, Vol. 83(4)

Performance evaluation of two simple causticizing control systems, TAPPI JOURNAL, April 2000, Vol. 83(4)

Journal articles
Open Access
Dynamic behavior of a pulp processing and reject refining plant, TAPPI JOURNAL, April 2000, Vol. 83(4)

Dynamic behavior of a pulp processing and reject refining plant, TAPPI JOURNAL, April 2000, Vol. 83(4)

Journal articles
Open Access
Chip size distribution for an ultra-high-yield sulfite process, TAPPI JOURNAL, April 2000, Vol. 83(4)

Chip size distribution for an ultra-high-yield sulfite process, TAPPI JOURNAL, April 2000, Vol. 83(4)

Journal articles
Open Access
Use of new oxidizing agents in a refiner : a route to high brightness pulp, TAPPI JOURNAL, April 2000, Vol. 83(4)

Use of new oxidizing agents in a refiner : a route to high brightness pulp, TAPPI JOURNAL, April 2000, Vol. 83(4)

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