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Model development for real oxygen delignification processes, TAPPI Journal October 2024
ABSTRACT: Previous extensive work has been done on modeling the oxygen delignification process, based on how the basic parameters, i.e., temperature, kappa number, concentration of alkali, and concentration of oxygen, affect the delignification rate. However, these models are not used extensively to evaluate the performance of real processes, primarily because they have not been able to properly consider all the essential issues affecting delignification in practice. Such issues include the mass transfer and consumption of oxygen, which defines the concentration of dissolved oxygen in the process, and the effect of that concentration on the delignification rate. In this paper, a new way to model the oxygen delignification process is used in which these parameters, among other smaller matters, are taken into account. The basic model and its parameters were defined by the information obtained from the literature, delignification made in the laboratory tests, and mill processes and mill tests. An essential aspect of these studies was the information obtained from the oxygen concentration measured in the residual gas obtained from the top of the reactor. With the aid of this measurement, it was possible to define more accurately the consumption of oxygen and partial pressure of oxygen that define the concentration of dissolved oxygen in the reactor. Using mill experiments, a model was formed that predicts the operation of the oxygen delignification process. The model was used to show how much the process could be improved by optimizing the charge of the oxygen. The mill experiments also confirmed that mass transfer of oxygen is modeled correctly enough, except when the charge of oxygen is very low and/or the mixing is not efficient enough. In that case, there is variation in the concentration of oxygen in the process that should be taken into account in the modeling.
Journal articles
Magazine articles
The Impact of Digitalization on our Changing Workforce, Paper360º March/April 2021
The Impact of Digitalization on our Changing Workforce, Paper360º March/April 2021
Journal articles
Magazine articles
Achieving Progressive Quality Culture Through Analytical Problem Solving, Paper360º March/April 2021
Achieving Progressive Quality Culture Through Analytical Problem Solving, Paper360º March/April 2021
Journal articles
Magazine articles
Young Professional Perspective: Shaping the Future Through Mentoring, Paper360º March/April 2021
Young Professional Perspective: Shaping the Future Through Mentoring, Paper360º March/April 2021
Journal articles
Magazine articles
Cepi: Looking Toward a Carbon Neutral 2050, Paper360º March/April 2021
Cepi: Looking Toward a Carbon Neutral 2050, Paper360º March/April 2021
Journal articles
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Uncovering Growth Opportunities in Graphic Papers, Paper360º March/April 2021
Uncovering Growth Opportunities in Graphic Papers, Paper360º March/April 2021
Journal articles
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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.
Journal articles
Magazine articles
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
Magazine articles
2021 TAPPI/PIMA Awards: Rising to the Challenge, Paper360º May/June 2021
2021 TAPPI/PIMA Awards: Rising to the Challenge, Paper360º May/June 2021