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Recovery boiler back-end heat recovery, TAPPI Journal March 2023
ABSTRACT: Sustainability and efficient use of resources are becoming increasingly important aspects in the operation of all industries. Recently, some biomass-fired boilers have been equipped with increasingly complex condensing back-end heat recovery solutions, sometimes also using heat pumps to upgrade the low-grade heat. In kraft recovery boilers, however, scrubbers are still mainly for gas cleaning, with only simple heat recovery solutions. In this paper, we use process simulation software to study the potential to improve the power generation and energy efficiency by applying condensing back-end heat recovery on a recovery boiler. Different configurations are considered, including heat pumps. Potential streams to serve as heat sinks are considered and evaluated. Lowering the recovery boiler flue gas temperature to approximately 65°C significantly decreases the flue gas losses. The heat can be recovered as hot water, which is used to partially replace low-pressure (LP) steam, making more steam available for the condensing steam turbine portion for increased power generation. The results indicate that in a simple condensing plant, some 1%•4% additional electricity could be generated. In a Nordic mill that provides district heating, even more additional electricity generation, up to 6%, could be achieved. Provided the availability of sufficient low-temperature heat sinks to use the recovered heat, as well as sufficient condensing turbine swallowing capacity to utilize the LP steam, the use of scrubbing and possibly upgrading the heat using heat pumps appears potentially useful.
Journal articles
Magazine articles
Editorial: Agility and adaptation in a dynamic business world, TAPPI Journal January 2021
ABSTRACT: Being agile and adaptive in this current business world is both necessary and beneficial. Throughout last year, we all continued to both directly and indirectly experience the dynamic world where we live. As we wll know, in early 2020 the pandemic gained momentum and has fundamentally altered our daily lives, both personally in how we live and professionally in how we work.
Journal articles
Magazine articles
Probing the molecular weights of sweetgum and pine kraft lignin fractions, TAPPI Journal June 2021
ABSTRACT: The present investigation undertook a systematic investigation of the molecular weight (MW) of kraft lignins throughout the pulping process to establish a correlation between MW and lignin recovery at different extents of the kraft pulping process. The evaluation of MW is crucial for lignin characterization and utilization, since it is known to influence the kinetics of lignin reactivity and its resultant physico-chemical properties. Sweetgum and pine lignins precipitated from black liquor at different pHs (9.5 and 2.5) and different extents of kraft pulping (30•150 min) were the subject of this effort. Gel permeation chromatography (GPC) was used to determine the number average molecular weight (Mn), mass average molecular weight (Mw), and polydispersity of the lignin samples. It was shown that the MW of lignins from both feedstocks follow gel degradation theory; that is, at the onset of the kraft pulping process low molecular weight-lignins were obtained, and as pulping progressed, the molecular weight peaked and subsequently decreased. An important finding was that acetobromination was shown to be a more effective derivatization technique for carbohydrates containing lignins than acetylation, the technique typically used for derivatization of lignin.
Journal articles
The role of mill engineering in water conservation, Frontline Focus, Volume 7, Issue 2
Frontline Focus, February 2011
Journal articles
Pipe Systems Under Attack, Frontline Focus, Volume 7, Issue 6
Frontline Focus, June/July 2011
Journal articles
The Problem of Paper Curl, Frontline Focus, Volume 7, Issue 10
Frontline Focus, November/December 2011
Journal articles
Foundation plants seeds for future academic research, TAPPI JOURNAL, February 1998, Vol. 81(2)
Foundation plants seeds for future academic research, TAPPI JOURNAL, February 1998, Vol. 81(2)
Journal articles
A man of ideas: 1998 Gunnar Nicholson Gold Medalist Douglas Wahren, TAPPI JOURNAL, February 1998, Vol. 81(2)
A man of ideas: 1998 gunnar nicholson gold medalist douglas wahren, TAPPI JOURNAL, February 1998, Vol. 81(2)
Journal articles
Clonal forestry and genetic engineering: where we stand, future prospects, and potential impacts on mill operations, TAPPI JOURNAL, February 1998, Vol. 81(2)
Clonal forestry and genetic engineering: where we stand, future prospects, and potential impacts on mill operations, TAPPI JOURNAL, February 1998, Vol. 81(2)
Journal articles
Champion international's long log pine chip mill: a nontraditional approach, TAPPI JOURNAL, February 1998, Vol. 81(2)
Champion international's long log pine chip mill: a nontraditional approach, TAPPI JOURNAL, February 1998, Vol. 81(2)