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Development of converging-diverging multi-jet nozzles for molten smelt shattering in kraft recovery boilers, TAPPI Journal March 2021
ABSTRACT: The effective shattering of molten smelt is highly desired in recovery boiler systems. Ideally, shatter jet nozzle designs should: i) generate high shattering energy; ii) create a wide coverage; and iii) minimize steam consumption. This study proposes a novel converging-diverging multi-jet nozzle design to achieve these goals. A laboratory setup was established, and the nozzle performance was evaluated by generating jet pressure profiles from the measurement of a pitot tube array. The results show that the shatter jet strength is greater with a large throat diameter, high inlet pressure, and a short distance between the nozzle exit and impingement position. Increasing the number of orifices generates a wider jet coverage, and the distance between the orifices should be limited to avoid the formation of a low-pressure region between the orifices. The study also demonstrates that an optimized converging-diverging multi-jet nozzle significantly outperformed a conventional shatter jet nozzle by achieving higher energy and wider coverage while consuming less steam.
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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).
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SetPoint: Donuts and Diversity, Paper360º March/April 2021
SetPoint: Donuts and Diversity, Paper360º March/April 2021
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The Impact of Digitalization on our Changing Workforce, Paper360º March/April 2021
The Impact of Digitalization on our Changing Workforce, Paper360º March/April 2021
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Achieving Progressive Quality Culture Through Analytical Problem Solving, Paper360º March/April 2021
Achieving Progressive Quality Culture Through Analytical Problem Solving, Paper360º March/April 2021
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Young Professional Perspective: Shaping the Future Through Mentoring, Paper360º March/April 2021
Young Professional Perspective: Shaping the Future Through Mentoring, Paper360º March/April 2021
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Cepi: Looking Toward a Carbon Neutral 2050, Paper360º March/April 2021
Cepi: Looking Toward a Carbon Neutral 2050, Paper360º March/April 2021
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Uncovering Growth Opportunities in Graphic Papers, Paper360º March/April 2021
Uncovering Growth Opportunities in Graphic Papers, Paper360º March/April 2021
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RMM Part 3: Belief-Driven Strategy, Paper360º March/April 2021
RMM Part 3: Belief-Driven Strategy, Paper360º March/April 2021
Journal articles
Magazine articles
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.