Prediction of rolling bed motion in rotating cylinders

Mellmann, Jochen; Specht, Eckehard; Liu, Xiaoyan

doi:10.1002/aic.10266

Cited by 54 publications

(22 citation statements)

References 24 publications

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“…Continuous rolling of the particles can be observed on the flight surface, while the material is being supplied continuously by the static bed which is resting in the flight. This phenomenon can be expected similar to the transverse motion of material in rotating cylinders without flights, where a larger part of the bulk bed moving with the wall (plug flow) is transported into a flowing cascading layer on the surface of the bed [14,24]. However, an interfacial boundary exists between these two regions having few particle thicknesses (see Fig.…”

Section: Analysis Of Transverse Flow At the Flight Surfacementioning

confidence: 67%

“…In the previous model of Schofield and Glikin, a single/thin layer of particles was considered in the cascading layer, and the inertial force acting on the rolling particles at the flight surface was neglected. A mathematical model was developed by considering a flowing cascading layer of few particle thicknesses at the flight surface similar to the case of rotating cylinder without flights by incorporating the inertial force based on the approaches followed by Mellmann et al [14] and Khakhar et al [15]. The velocity profile has been determined by treating the granular flow as a continuum.…”

Section: Introductionmentioning

confidence: 99%

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Transverse flow at the flight surface in flighted rotary drum

et al. 2015

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Section: Analysis Of Transverse Flow At the Flight Surfacementioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Transverse flow at the flight surface in flighted rotary drum

et al. 2015

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“…With increasing filling degree, the length of DABC will be increased, but the depth of the active layer and, accordingly, the length of DA and BC in the active layer will be also increased [17]. Therefore, a strong effect of the filling degree on the circulation time cannot be expected.…”

Section: Effect Of Filling Degreementioning

confidence: 99%

“…As the rotation speed is increased, the active layer thickness (and, thus, the length of DA and BC in Fig. 5) will also increase [17][18], leading to a shorter path length in the stagnant layer. Consequently, an obvious decrease of T C,i with increasing rotation speed can be observed.…”

Section: Effect Of Rotation Speedmentioning

confidence: 99%

Experimental Study on Time Features of Particle Motion in Rotating Drums

Liu

Zhang

2011

Chem Eng & Technol

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Rotating drums are widely used in pharmaceutical industry to coat tablets. The motion of the tablet particle is one of the most important factors affecting coating uniformity. The purpose of the research is to experimentally investigate two important time variables for the coating process, residence time and turnover time, and their dependence on operating parameters (rotation speed and filling degree of the drum). The average residence time was found to decrease with increasing rotation speed and filling degree. The average turnover time was observed to increase approximately linearly with the inverse of the drum speed, but was found to be independent of the filling degree. A dimensionless time variable, the fractional residence time, i.e., the residence time divided by the turnover time, was introduced. Analysis showed that the fractional residence time could be a good indicator of coating uniformity. Results of the present work provide useful information for theoretical modeling which may ultimately serve as a tool for coating optimization. IntroductionRotating drums are widely used for coating tablets in pharmaceutical applications. The coating time and coating uniformity is determined predominately by residence time of the tablet and its appearance frequency on the surface of the bed, where the tablet is in direct contact with hot air and liquid spray [1][2]. In recent years, efforts have been devoted to study factors that may affect the residence time, such as operating parameters (drum speed n 1) and filling degree f), drum dimensions (diameter D and length L), and properties of the tablet particles (size d, shape, etc.). DEM (discrete element method) simulations and experiments have been performed in pan coaters or rotating drums using various techniques [2][3][4][5][6][7][8].Although some qualitative conclusions can be made, quantitative comparison between measurements in the literature is rather difficult. One reason is that most of these experiments were performed on 3D rotating drums and measured results could be affected by the total operating time of the drum due to the mixing process occurring in the direction of the drum length [6]. Moreover, some of these studies give inconclusive findings. It was found that the residence time decreases with increasing filling degree [2-4], but the residence time per pass was observed to be independent of the filling degree [6][7][8][9]. It is thus imperative to study in detail the motion of particles in rotating drums. Numerous works have been reported in the literature on measurement of particle velocity in 3D rotating drums [10][11][12][13], however, systematic investigations on time features of the particles are relatively rare.For purposes where the effects of filling degrees and drum speeds are to be assessed, quasi-2D experiments are the easiest way [1,14]. In such systems, the residence time can easily be estimated using tracer particles. The objective of the present work is to study experimentally the time features of particle motion in quasi-2D rotatin...

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“…O incremento do tamanho das partículas favorece a separação das mesmas em altas velocidades de rotação, começando a se formar um arco com um pequeno espaço de ar no interior, obtendo-se o movimento de partículas em cascata (cascading Comumente, os secadores rotativos são operados a baixas velocidades de rotação, mas, a mistura das partículas permite melhorar a transferência de calor, massa e sua homogeneidade graças aos movimentos de partículas em queda (slumping) e partículas rolante (rolling) do regime em cascata (MELLMANN, 2004). Kelbert et al (1991) estudou a mistura das partículas e a transferência de calor em um leito no regime de partículas rolante, demonstrando que a mistura tem uma grande influência na distribuição de temperatura dentro do leito de sólidos.…”

Section: Produção De Fungos Entomopatogênicosunclassified

Avaliação de um biorreator rotativo para fermentação em estado sólido

Agudelo¹,

María²

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Lina María Grajales AgudeloA Deus por permitir a realização do meu grande sonho de estudar no Brasil.A mis papitos y a mi Leín por apoyarme siempre, en todos los proyectos de mi vida, los quiero mucho !!!!.Ao meu orientador João Cláudio pela paciência, pelos conhecimentos, pela ajuda e sobre todo por permitir que eu fizesse parte da sua grande família acadêmica. A experiência foi um sucesso, lhe agradeço muitíssimo por TUDO. Obrigada "pai".Aos professores José Freire, Maria do Carmo, Cida e José Antônio, membros da banca, por acrescentar a qualidade do trabalho mediante suas recomendações, conselhos e sugestões.Ao meu grande Maestro e Amigo Carlos Eduardo por me ensinar todo o que podia precisar para me enfrentar na vida, longe da Faculdade, longe da Colômbia, longe de você. Por ter me agüentado tantos anos e ajudar-me a crescer pessoal e profissionalmente. Na verdade não tenho palavras para expressar minha gratidão e admiração por você, só posso falar ...À professora Cida por ser quase uma mãe para mim e por ter me ajudado muito na minha vinda ao Brasil.Ao professor Roger por fazer parte da minha formação acadêmica e acrescentar meus conhecimentos na área de engenharia de processos.Ao Rodiak por caminhar do meu lado em busca da felicidade, simplesmente, adoro você!!!!. AgradecimentosLina María Grajales Agudelo Agradecimentos À Cinthya, Rafis, Harvey e Camilo por serem meus amigos e poder contar com vocês nas situações que se apresentam sempre, e que, se complicam ainda mais quando estamos fora de casa.Ao Pablito, Alex e a Kelly por compartilhar aqueles incríveis momentos durante e depois das aulas.À Carol por se tornar uma grande amiga em muito pouco tempo e pelos longos períodos de companhia no laboratório.À Milena, uma super amiga, por me ajudar na aprendizagem do português.Ao João e à Natália por colaborar na parte experimental e facilitar-me o desenvolvimento do trabalho.Aos técnicos do laboratório por fornecer-me as ferramentas necessárias para concluir com grande sucesso meu projeto.Ao Cesar e os outros colegas do laboratório que me agüentaram durante este tempo.Ao CNPq e ao programa PEC-PG que financiaram meus dois anos de mestrado.A lista é longa!!!!. Peço desculpas para quem não está nesta lista e que de alguma maneira têm influenciado nas grandes mudanças da minha vida. AbstractThis work is aimed to contribute to the development of a rotary drum bioreactor forMetarhiziun anisopliae spore production by Solid State Fermentation, using rice as a substrate. This work is comprised of two parts, one corresponding to particle moving analysis and another on thermal aspects. The first part assesses both the mixture and the movement of particles of rice in a Plexiglas rotary drum, in order to identify the optimal operational conditions for the best particle mixture. Tracer method was applied to assess the particle mixture and two techniques were applied to assess the mixture: manual sampling and image analysis using Lenseye (E&CS Programs) software. The flow regime and particle velocities were also identified ...

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Prediction of rolling bed motion in rotating cylinders

Abstract: A mathematical model for the range of rolling bed motion has been developed to

Cited by 54 publications

References 24 publications

Transverse flow at the flight surface in flighted rotary drum

Transverse flow at the flight surface in flighted rotary drum

Experimental Study on Time Features of Particle Motion in Rotating Drums

Avaliação de um biorreator rotativo para fermentação em estado sólido

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