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STUDY OF THE CONSUMPTION OF OXIDIZING CHEMICAL REAGENTS IN THE BLEACHING OF KRAFT PULPS Case Study: The Navigator Company Industrial Process in Figueira da Foz
No full textDissertação de Mestrado em Engenharia Química apresentada à Faculdade de Ciências e TecnologiaThe Navigator Company was the third-largest national exporter in 2022, with its primary activity being the production of pulp and paper. With a focus on continuous improvement, the company aims to optimize the production process and improve pulp properties. The kraft cooking process is used for wood delignification and the transformation of wood into raw pulp, followed by Elemental Chlorine Free (ECF) bleaching. In this sequence, the reagents used are aimed at removing residual lignin and other impurities to achieve the target brightness in the pulp without affecting productivity or paper quality.This dissertation aims to analyze the consumption of oxidizing chemical compounds in kraft pulp bleaching with the goal of identifying opportunities for improvement in their utilization. Data collection from The Navigator Company's paper pulp production complex located in Figueira da Foz, using historically collected passive data, allowed for the identification of trends and patterns in reagent consumption and inherent variables.For direct process data collection, the Uniformance Process Studio software was used. For a comprehensive study of the process and key associated variables, Microsoft Excel served as the tool for data collection and storage, while JMP Pro® software functioned as the statistical tool for data processing and analysis.Exploratory data analysis (EDA) revealed significant proportional relationships: a lower kappa index (IK) measured after oxygen delignification corresponded to lower consumption of oxidizing reagents. Conversely, an inverse proportional relationship was observed between the brightness of the pulp fed into the first stage of chlorine dioxide and the consumption of chemical reagents in bleaching. That is, the higher the pulp brightness, the lower the need for reagent addition to achieve the target brightness of 90.3% ISO.The increase in the daily pulp production target at the facility was associated with an exponential rise in chemical oxygen demand (COD) and sodium losses in both washing equipment, located before and after oxygen delignification, more prominently in the raw pulp washer (DDPC). Additionally, EDA revealed a somewhat unexpected relationship: higher incorporations of E. globulus wood resulted in higher consumption of oxidizing reagents in bleaching.After applying the method of selecting key explanatory variables for response variability (Partial Least Squares, PLS), a multiple linear regression model was generated. The generated model demonstrated good fit quality, with an R-squared value of 0.809, and allowed for the quantification of certain effects, including an increase of one unit in IK measured after delignification, resulting in a 4.13 kg/tAD increase in oxidant consumption in bleaching. This reflects the need for adequate delignification of the pulp for sustainable reagent consumption. Additionally, a 0.01 bar increase in the feed pressure to the DDPC washer led to a 0.8118 kg/tAD reduction in oxidizing reagent consumption.The ease of cooking of the E. globulus species, as often reported in the literature, was confirmed through alkaline charge analysis and an estimate of yield in kg pulp/rotation, with both variables showing better results with higher incorporations of this species. Seasonal effects, the impact of increased incorporations of this preferred species, and the influence of its importation were also examined. The effect of incorporating the E. nitens species on alkaline charge was studied due to its lower density, but no statistically significant relationship was found.In conclusion, despite the percentage of E. globulus incorporation not emerging as a significant variable in the multiple linear regression model for response variability, its increased incorporation does influence the consumption of oxidizing chemical reagents in bleaching due to the ease of cooking of this species, allowing for increased production. Due to constraints in the washing capacity of the process, insufficient pulp washing leads to reduced efficiency in the oxygen delignification stage (higher IK after delignification), resulting in a higher content of residual lignin in the pulp sent for bleaching.The results of this study have the potential to contribute to the reduction of chemical reagent consumption in bleaching by identifying the factors with the greatest influence on the response and their interdependencies, ultimately reducing costs, optimizing the process, and minimizing environmental impact.A The Navigator Company foi em 2022 a terceira maior exportadora nacional, sendo a sua principal atividade a produção de pasta e papel. Numa perspetiva de melhoria contínua, a empresa visa a otimização do processo de produção e melhoria de propriedades da pasta. O cozimento kraft é o processo utilizado na deslenhificação e transformação da madeira em pasta crua, sendo esta branqueada através de uma sequência ECF (Elemental Chlorine Free). Nessa sequência, os reagentes utilizados visam a remoção da lenhina residual e de outras impurezas, de modo a atingir a brancura objetivo na pasta, sem condicionar a produtividade nem a qualidade papeleira do produto final. A presente dissertação pretende analisar o consumo de compostos químicos oxidantes no branqueamento de pastas kraft, com o objetivo de identificar oportunidades de melhoria na sua utilização. A recolha de dados do complexo industrial de produção de pasta para papel da The Navigator Company localizada na Figueira da Foz, usando dados históricos recolhidos de forma passiva, permitiu identificar tendências e padrões no consumo de reagentes e nas variáveis inerentes. Para a recolha de dados diretamente do processo, foi usado o software Uniformance Process Studio. Para o estudo processual completo e principais variáveis associadas recorreu-se ao Microsoft Excel como ferramenta de recolha e armazenamento de dados, enquanto o software JMP Pro® funcionou como ferramenta estatística de tratamento e análise de dados. A análise exploratória de dados (AED) permitiu observar relações de proporcionalidade importantes: verificou-se que a um índice kappa (IK) mais baixo, medido após a deslenhificação da pasta com oxigénio, correspondia um menor consumo de reagentes oxidantes. Por outro lado, verificou-se uma relação de proporcionalidade inversa entre a brancura da pasta alimentada ao primeiro estágio de dióxido de cloro e o consumo de reagentes químicos no branqueamento, isto é, quanto maior for o grau de brancura da pasta, menor é a necessidade de adição de reagentes para atingir a brancura objetivo de 90.3 % ISO. Associou-se o aumento do objetivo diário de produção de pasta na instalação a uma subida exponencial da carência química de oxigénio (CQO) e perdas de sódio em ambos os equipamentos de lavagem, localizados antes e após a deslenhificação com oxigénio, mais expressivamente no lavador de pasta crua (DDPC). Para além disso, a AED revelou uma relação algo inesperada: maiores incorporações de madeira de E. globulus causam um maior consumo de reagentes oxidantes no branqueamento. Após a aplicação do método de seleção das principais variáveis explicativas da variabilidade da resposta (Partial Least Squares, PLS), gerou-se um modelo de regressão linear múltipla. O modelo gerado revelou possuir uma boa qualidade de ajuste, com R2 de 0.809, e permitiu quantificar determinados efeitos, nomeadamente: um acréscimo de uma unidade de IK medido após a deslenhificação, o consumo de oxidante no branqueamento aumenta 4.13 kg/tAD de pasta, que reflete a necessidade de uma adequada deslenhificação da pasta, para um consumo de reagentes sustentável; o aumento de 0.01 bar na pressão de alimentação ao lavador DDPC, reflete-se numa diminuição do consumo de reagentes oxidantes de 0.8118 kg/tAD de pasta.Comprovou-se a facilidade de cozimento da espécie E. globulus várias vezes relatada na literatura, através da análise da carga alcalina e de uma estimativa do rendimento, em kgpasta/rotação, em que ambas as variáveis se mostraram superiores para maiores incorporações desta espécie. Verificou-se também o efeito da sazonalidade, o efeito das maiores incorporações desta espécie predileta e a influência da importação da mesma. Estudou-se também o efeito da incorporação da espécie E. nitens na carga alcalina, visto esta ser a espécie de menor densidade. No entanto, não se obteve uma relação com significado estatístico pertinente. Por fim, concluiu-se que, apesar da percentagem de incorporação de E.globulus não se revelar no modelo de regressão linear múltipla como uma variável com efeito significativo na variabilidade de resposta, o aumento da sua incorporação tem influência no consumo de reagentes químicos oxidantes no branqueamento, uma vez que a facilidade de cozimento da espécie E.globulus, permite o aumento de produção. Por constrangimentos na capacidade de lavagem do processo, a insuficiência de lavagem da pasta leva à diminuição da eficiência da etapa de deslenhificação com oxigénio (maior IK após deslenhificação), o que representa um maior teor de lenhina residual na pasta encaminhada para o branqueamento. Os resultados do estudo efetuado possuem potencial de contribuição para redução do consumo de reagentes químicos no branqueamento, através de identificação dos fatores com maior influência na resposta e respetivas interdependências, para a redução de custos, otimização do processo e minimização do impacte ambiental
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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