R. B. Demuner, C. Faria, Américo de Almeida, P. Pignaton
Cellulose pulp’s physical-mechanical properties are determined by laboratory tests obtained from prepared handsheets. However, this procedure is time intensive and presents a lead time until the results are available, hindering its utilization for monitoring and decision-making in a pulp mill. In this context, developing real-time solutions for physical-mechanical properties prediction is fundamental. This work applied a mathematical modeling approach to develop a soft sensor for tensile index monitoring. The mathematical model considers online morphology measurements obtained from the last bleaching stage outlet stream and important process variables for tensile index prediction. The results obtained are satisfactory compared to laboratory results, presenting a mean absolute percentual error of 2.5%, which agrees with the laboratory testing method’s reproducibility.
{"title":"On the usage of online fiber measurements for predicting bleached eucalyptus kraft pulp tensile index — an industrial case","authors":"R. B. Demuner, C. Faria, Américo de Almeida, P. Pignaton","doi":"10.32964/tj21.7.365","DOIUrl":"https://doi.org/10.32964/tj21.7.365","url":null,"abstract":"Cellulose pulp’s physical-mechanical properties are determined by laboratory tests obtained from prepared handsheets. However, this procedure is time intensive and presents a lead time until the results are available, hindering its utilization for monitoring and decision-making in a pulp mill. In this context, developing real-time solutions for physical-mechanical properties prediction is fundamental. \u0000This work applied a mathematical modeling approach to develop a soft sensor for tensile index monitoring. The mathematical model considers online morphology measurements obtained from the last bleaching stage outlet stream and important process variables for tensile index prediction. The results obtained are satisfactory compared to laboratory results, presenting a mean absolute percentual error of 2.5%, which agrees with the laboratory testing method’s reproducibility.","PeriodicalId":22255,"journal":{"name":"Tappi Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42790093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Excessive calender vibration affects all styles of calender stacks from single to multi-nip, all hard rolls, or a combination of hard and soft rolls. Calender vibration can be forced vibration or self-excited vibration. Forced vibration occurs at the first few harmonics of the calender roll rotational speeds and is caused by imbalance, misalignment, eccentricity, etc. Self-excited vibration, the focus of this paper, occurs at higher frequencies. Feedback paths for self-excited vibration must be understood in order to ameliorate the problem. This is presented in the context of the historical development of the theory of self-excited feedback mechanisms, followed by a survey of self-excited feedback mechanisms in various types of calender stacks. Methodology to determine which feedback path is present and techniques to control or eliminate the resulting vibration follow. To obtain a flavor of the types of problems faced and practical remedial actions, a variety of experiences with barring issues are provided.
{"title":"Calender barring review with experiences","authors":"J. Zwart","doi":"10.32964/tj21.7.377","DOIUrl":"https://doi.org/10.32964/tj21.7.377","url":null,"abstract":"Excessive calender vibration affects all styles of calender stacks from single to multi-nip, all hard rolls, or a combination of hard and soft rolls. Calender vibration can be forced vibration or self-excited vibration. Forced vibration occurs at the first few harmonics of the calender roll rotational speeds and is caused by imbalance, misalignment, eccentricity, etc. Self-excited vibration, the focus of this paper, occurs at higher frequencies.\u0000 Feedback paths for self-excited vibration must be understood in order to ameliorate the problem. This is presented in the context of the historical development of the theory of self-excited feedback mechanisms, followed by a survey of self-excited feedback mechanisms in various types of calender stacks. Methodology to determine which feedback path is present and techniques to control or eliminate the resulting vibration follow. To obtain a flavor of the types of problems faced and practical remedial actions, a variety of experiences with barring issues are provided.","PeriodicalId":22255,"journal":{"name":"Tappi Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41427490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Bridge March 2021 contains research digests covering a wide range of developmental, emotional, and behavioural conditions experienced by young people, including a focus on mood disorders in autism.
{"title":"March 2021","authors":"","doi":"10.32964/tj20.3","DOIUrl":"https://doi.org/10.32964/tj20.3","url":null,"abstract":"The Bridge March 2021 contains research digests covering a wide range of developmental, emotional, and behavioural conditions experienced by young people, including a focus on mood disorders in autism.","PeriodicalId":22255,"journal":{"name":"Tappi Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2021-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42302889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Please note that the Mass Communication Division has opted for asynchronous sessions. This means session chairs will not need to coordinate or moderate the panels this year. Considering the number of sessions, time zones, etc. of our presenters and chairs, we feel the best option is for each presenter to individually record and upload their presentation as per the instructions being sent by ICA HQ.
{"title":"May 2020","authors":"Danilo Yanich","doi":"10.37865/jafe.is052020","DOIUrl":"https://doi.org/10.37865/jafe.is052020","url":null,"abstract":"Please note that the Mass Communication Division has opted for asynchronous sessions. This means session chairs will not need to coordinate or moderate the panels this year. Considering the number of sessions, time zones, etc. of our presenters and chairs, we feel the best option is for each presenter to individually record and upload their presentation as per the instructions being sent by ICA HQ.","PeriodicalId":22255,"journal":{"name":"Tappi Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42678450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"How to use total dissolved solids measurements to evaluate the performance of diffuser washers-A mill study","authors":"Riku Kopra, A. Pesonen, Jari Käyhkö, O. Dahl","doi":"10.32964/TJ19.4.173","DOIUrl":"https://doi.org/10.32964/TJ19.4.173","url":null,"abstract":"","PeriodicalId":22255,"journal":{"name":"Tappi Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42927584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For mills making paper with recovered fiber, removal of hydrophobic contaminants is essential for trouble-free operation of paper machines. Significant cost savings on paper machine operation can be achieved by reducing deposits, which results in better quality, reduced downtime, increased fiber yield, and reduced energy consumption. Bubble nucleation separation (BNS) is a relatively new process for removing hydrophobic particles. When vacuum is applied to a slurry, dissolved gas bubbles nucleate on hydrophobic particles and drag them to the surface for easy removal. We constructed a 16-L batch unit to evaluate the effect of operating parameters on removal of hydrophobic particles, using statistical design of experiments. These results were used to guide our design of a 16-L continuous unit. We tested this unit on laboratory and mill samples. The removal of 60%–80% of hydrophobic particles was achieved with a low reject rate of < 2%. Following on this success, we built a 200-L pilot unit and tested it in our pilot plant. With promising results there, we installed the pilot unit at a commercial paper recycling mill. Over the course of several mill trials, we showed that it was possible to remove a considerable amount of suspended solids from paper machine white water with less than 2% rejects. Unfortunately, due to the unit only treating 50 L/min and the mill flow being 12000 L/min, we were not able treat a sufficient portion of the white water to know whether a large-scale implementation of BNS would improve paper machine runnability. Application: If implemented in a paper machine white water loop, this technology could provide a way to control stickies and dirt, without adding any chemicals. According to the American Forest and Paper Association (AF&PA), 77% of paper mills in the United States use some form of recovered fiber [1]. In spite of advances in screens and cleaners, we do not have a satisfactory process for the removal of hydrophobic contaminants, especially small particles that pass through slotted screens. Hydrophobic particles in paper recycling, also called stickies, arise from pressure sensitive adhesives, natural pitch, book bindings, postage stamps, envelopes, inks, etc. Often, stickies are comprised of mixtures of materials including, wax, polystyrene butadiene, polyvinyl acetate, silicones, wood extractives, and any other polymers in the recovered paper. In paper recycling, the removal of stickies is of paramount importance for trouble-free operation of paper machines. Stickies accumulate in the paper machine white water and eventually agglomerate and deposit on wires and felts. These deposits have drastic effects on the paper machine productivity. Cost savings on paper machines due to reducing stickies deposits can be substantial. Tom Friberg estimated in 1996 that the cost impact of stickies to all paper recycling mills combined in the United States is about $700 million per year [2]. Flotation processes are widely used in t
{"title":"A novel unit operation to remove hydrophobic contaminants","authors":"C. Houtman, S. Aziz, Robert L. de Jong, M. Doshi","doi":"10.32964/TJ19.4.207","DOIUrl":"https://doi.org/10.32964/TJ19.4.207","url":null,"abstract":"For mills making paper with recovered fiber, removal of hydrophobic contaminants is essential for trouble-free operation of paper machines. Significant cost savings on paper machine operation can be achieved by reducing deposits, which results in better quality, reduced downtime, increased fiber yield, and reduced energy consumption. Bubble nucleation separation (BNS) is a relatively new process for removing hydrophobic particles. When vacuum is applied to a slurry, dissolved gas bubbles nucleate on hydrophobic particles and drag them to the surface for easy removal. We constructed a 16-L batch unit to evaluate the effect of operating parameters on removal of hydrophobic particles, using statistical design of experiments. These results were used to guide our design of a 16-L continuous unit. We tested this unit on laboratory and mill samples. The removal of 60%–80% of hydrophobic particles was achieved with a low reject rate of < 2%. Following on this success, we built a 200-L pilot unit and tested it in our pilot plant. With promising results there, we installed the pilot unit at a commercial paper recycling mill. Over the course of several mill trials, we showed that it was possible to remove a considerable amount of suspended solids from paper machine white water with less than 2% rejects. Unfortunately, due to the unit only treating 50 L/min and the mill flow being 12000 L/min, we were not able treat a sufficient portion of the white water to know whether a large-scale implementation of BNS would improve paper machine runnability. Application: If implemented in a paper machine white water loop, this technology could provide a way to control stickies and dirt, without adding any chemicals. According to the American Forest and Paper Association (AF&PA), 77% of paper mills in the United States use some form of recovered fiber [1]. In spite of advances in screens and cleaners, we do not have a satisfactory process for the removal of hydrophobic contaminants, especially small particles that pass through slotted screens. Hydrophobic particles in paper recycling, also called stickies, arise from pressure sensitive adhesives, natural pitch, book bindings, postage stamps, envelopes, inks, etc. Often, stickies are comprised of mixtures of materials including, wax, polystyrene butadiene, polyvinyl acetate, silicones, wood extractives, and any other polymers in the recovered paper. In paper recycling, the removal of stickies is of paramount importance for trouble-free operation of paper machines. Stickies accumulate in the paper machine white water and eventually agglomerate and deposit on wires and felts. These deposits have drastic effects on the paper machine productivity. Cost savings on paper machines due to reducing stickies deposits can be substantial. Tom Friberg estimated in 1996 that the cost impact of stickies to all paper recycling mills combined in the United States is about $700 million per year [2]. Flotation processes are widely used in t","PeriodicalId":22255,"journal":{"name":"Tappi Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69473096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Different strategies aimed at reducing the negative impact of fillers on paper strength have been the objective of many studies during the past few decades. Some new strategies have even been paten ...
{"title":"A novel predictive method for filler coflocculation with cellulose microfibrils","authors":"I. S. Pio, K. Johansson, P. Krochak","doi":"10.32964/tj18.11.653","DOIUrl":"https://doi.org/10.32964/tj18.11.653","url":null,"abstract":"Different strategies aimed at reducing the negative impact of fillers on paper strength have been the objective of many studies during the past few decades. Some new strategies have even been paten ...","PeriodicalId":22255,"journal":{"name":"Tappi Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48400394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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