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An Investigation of the role of mixing conditions during polymeric retention aid addition on the adsorption homogeneityLuettgen, Christopher O. 01 January 1992 (has links)
No description available.
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An investigation of the effects of polymer partitioning on fines retentionMiller, Charles E. 01 January 1989 (has links)
No description available.
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The Effects of Retention Aid Dosage and Mechanical Energy Dissipation on Fiber Flocculation in a Flow ChannelWeseman, Brian D. 23 December 2004 (has links)
Formation plays an important role in the end-use properties of paper products,
but before formation can be optimized to achieve superior properties, an understanding
about the causes of formation must be developed. Formation is caused by variations in
the basis weight of paper that are results of fiber floc formation before and during the
forming of the sheet. This project is a first step in a larger research program aimed at
studying formation. By observing the effects that mechanical energy dissipation (in the
form of turbulence) and retention chemical dosage have on floc formation, we may
develop a better understanding of how to control formation.
In this study, a rectangular cross-section flow channel was constructed to aid in
the acquisition of digital images of a flowing fiber suspension. The furnish consisted of a
55:45 spruce:pine bleached market pulp mix from a Western Canadian mill. Turbulence
was varied by changing the flow rate; Reynolds numbers achieved range from 20,000 to
40,000. The retention aid used was a cationic polyacrylamide with a medium charge
density. Dosage of the retention aid was varied from 0 to 2 pounds per ton OD fiber.
Digital images of the flowing fiber suspension were acquired with a professional digital
SLR camera with a forensics-quality lens. Three separate image analysis techniques were
used to measure the flocculation state of the fiber suspension: morphological image
operations, formation number analysis, and fast Fourier transform analysis.
Morphological image analysis was capable of measuring floc size increases seen in
the acquired floc images. It was shown how floc diameter could increase simultaneously
with decreasing total floc area and total floc number. A regression model relating
retention aid dosage and energy dissipation was constructed in an effort to predict
flocculation. The regression model was used to predict F2 (formation number squared)
results from the study. The interaction effect RE was shown to have a differing effect across the retention aid dosage levels. As a result, this model and technique may prove to
be a beneficial tool in optimizing retention aid applications.
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High-Speed Imaging of Polymer Induced Fiber FlocculationHartley, William H. 22 March 2007 (has links)
This study presents quantitative results on the effect on individual fiber length during fiber flocculation. Flocculation was induced by a cationic polyacrylamide (cPAM). A high speed camera recorded 25 second video clips. The videos were image-analyzed and the fiber length and the amount of fiber in each sample were measured. Prior to the flocculation process, fibers were fractionated into short and long fibers. Trials were conducted using the unfractionated fiber, short fiber, and long fiber. The short and long fibers were mixed in several trials to study the effect of fiber length. The concentration of cPAM was varied as well as the motor speed of the impeller (RPM). It was found that the average fiber length decreased more rapidly with increasing motor speed. Increasing the concentration of cPAM also led to a greater decrease in average fiber length. A key finding was that a plateau was reached where further increasing the amount of cPAM had no effect. Hence, fibers below a critical length resisted flocculation even if the chemical dose or shear was increased. This critical length was related to the initial length of the fiber.
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The Influence of Chemical and Mechanical Flocculation on Paper Formation as Assessed by the Grammage Probability DistributionJing, Yan 18 August 2009 (has links)
No description available.
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Nanopartículas de sílica coloidal como agente da química da parte úmida na fabricação de papel. / Colloidal silica nanoparticles for wet end used for paper machines.Fernandes, Evanice Torres 01 February 2013 (has links)
No processo de fabricação do papel, a formação é muito importante, pois impacta na qualidade do produto assim como na maquinabilidade e produção. Para uma boa formação, um sistema de retenção e drenagem com aditivos eficientes é muito importante. Desta forma uma sílica nanopartículada, devido a sua área superficial, pode ser a diferença neste sistema e na resistência a úmido na fabricação de papel. Através de testes que simulam a floculação padrão (espalhamento de luz dinâmico) tentou-se identificar qual seriam as variáveis (pH, concentração iônica do meio, tamanho de nanopartícula) que influenciariam no processo de floculação assim como verificar qual o mecanismo e o que ocorre com o floco durante a floculação/defloculação/refloculação. Utilizando como modelo uma máquina de papel offset que usa fibra de celulose branqueada e carga verifica-se a condição de fabricação (receita) e o sistema de retenção e drenagem utilizado atende os parâmetros de resistência e formação da folha de papel. Constatou-se que o pH exerce uma influência no tamanho do floco formado e que o mecanismo de refloculação, para diferentes tipos de cisalhamento, são diferentes. A concentração ideal de sílica e polímero pode ser otimizada a fim de trazer uma redução de custo e melhoria do processo. / In the process of paper manufacturing, formation is important to product quality, runnability and production. To have a good formation, a retention and drainage system with efficient chemicals is important. Thus silica nanoparticles, because their surface area, may be the difference in this systems and wet resistance in the paper manufacture. Using flocculation tests (light dynamic scattering equipment) were identified what conditions (pH, ionic concentration, size particle) had some influence on the flocculation process and verify what is the mechanism and what do happen with the floc during the flocculation/deflocculation/reflocculation. To have an offset paper machine using bleached cellulose and filler, it checked if the mill`s recipe and the retention and drainage system correspond the level of resistance and formation required. I found the pH has had influence in the floc and have had differences in the reflocculation mechanism when submitted to different shears (sonification and stirring). The polymer and silica dosage can be optimized to a saving cost and to improve the process.
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Nanopartículas de sílica coloidal como agente da química da parte úmida na fabricação de papel. / Colloidal silica nanoparticles for wet end used for paper machines.Evanice Torres Fernandes 01 February 2013 (has links)
No processo de fabricação do papel, a formação é muito importante, pois impacta na qualidade do produto assim como na maquinabilidade e produção. Para uma boa formação, um sistema de retenção e drenagem com aditivos eficientes é muito importante. Desta forma uma sílica nanopartículada, devido a sua área superficial, pode ser a diferença neste sistema e na resistência a úmido na fabricação de papel. Através de testes que simulam a floculação padrão (espalhamento de luz dinâmico) tentou-se identificar qual seriam as variáveis (pH, concentração iônica do meio, tamanho de nanopartícula) que influenciariam no processo de floculação assim como verificar qual o mecanismo e o que ocorre com o floco durante a floculação/defloculação/refloculação. Utilizando como modelo uma máquina de papel offset que usa fibra de celulose branqueada e carga verifica-se a condição de fabricação (receita) e o sistema de retenção e drenagem utilizado atende os parâmetros de resistência e formação da folha de papel. Constatou-se que o pH exerce uma influência no tamanho do floco formado e que o mecanismo de refloculação, para diferentes tipos de cisalhamento, são diferentes. A concentração ideal de sílica e polímero pode ser otimizada a fim de trazer uma redução de custo e melhoria do processo. / In the process of paper manufacturing, formation is important to product quality, runnability and production. To have a good formation, a retention and drainage system with efficient chemicals is important. Thus silica nanoparticles, because their surface area, may be the difference in this systems and wet resistance in the paper manufacture. Using flocculation tests (light dynamic scattering equipment) were identified what conditions (pH, ionic concentration, size particle) had some influence on the flocculation process and verify what is the mechanism and what do happen with the floc during the flocculation/deflocculation/reflocculation. To have an offset paper machine using bleached cellulose and filler, it checked if the mill`s recipe and the retention and drainage system correspond the level of resistance and formation required. I found the pH has had influence in the floc and have had differences in the reflocculation mechanism when submitted to different shears (sonification and stirring). The polymer and silica dosage can be optimized to a saving cost and to improve the process.
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