Analysis of the chaotic dynamics of a high-flux CFB riser using solids concentration measurements

Manyele, Samwel Victor; Zhu, Jianfeng; Khayat, Roger E.; Pärssinen, Janne

doi:10.1016/s1672-2515(07)60253-x

Cited by 13 publications

(49 citation statements)

References 23 publications

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“…Ref. [4,17] ), the feeding of air is parallel to the feeding of solids at the entrance of the downer section. After passing through the downer, the flow passes through a curve and is then conducted to the riser.…”

Section: Methodsmentioning

confidence: 99%

“…[3] While new techniques of data analysis are being developed to account for complex dynamic behaviour of gas-solids flow in CFBs, the most applicable techniques are statistical, spectral, and most recently, chaos analyses. [4] Since the early 1990s, deterministic chaos theory has been applied to characterise the dynamics of multiphase systems, in which the nonlinear flow characteristics are represented with a strange attractor reconstructed from the time series of system variables. [5] According to Huilin et al, [6] deterministic chaos theory provides, at least in principle, the tools needed to analyse the chaotic behaviour of hydrodynamic systems and estimate the minimum degrees of freedom required to describe such systems.…”

Section: Introductionmentioning

confidence: 99%

“…Higher entropy signifies a higher rate of information loss (or lower predictability) and also shows stronger dependency on small disturbances. [4] The technique has so far been developed and extended to the study of CFB dynamics using pressure and voidage or solids concentration fluctuations. However, most of the studies were based on pressure fluctuations, [13][14][15] and few were done analysing signal of solids concentration (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Ref. [4] ). Therefore, in this paper the time dependency of solids concentration in the high-flux riser was analysed in the time domain, and a special study was done using deterministic chaos analysis of solids concentration signals.…”

Section: Introductionmentioning

confidence: 99%

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Study of gas–solids flow in a short CFB riser by statistical and chaotic deterministic analysis of optical fibre probe signals

Castilho

Cremasco

2012

Can J Chem Eng

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In this work, a short CFB riser with a height of 2.42 m and an ID of 82 mm was operated under different dilute operating conditions to study the fluid dynamics of FCC catalyst particles (d p = 80 m, p = 902 kg/m 3 ) in air. The electrical signals from the optical fibre probe were sampled at a frequency of 1000 Hz for a period of 30 s and were obtained at different positions along the radius and height of the riser. Data were analysed using both statistical methods (time average, standard deviation and frequency distribution) and chaos methods (construction of attractors; correlation dimension, D ML ; and Kolmogorov entropy, K ML ). Some results on solids holdup deduced from the electrical signal are also presented for the developed zone of the riser. It was verified that for very dilute conditions, increasing gas velocity produces more complex and less predictable fluctuations in solids concentration, while increasing solids flux generally reduces complexity and increases predictability. However, results for the most dilute condition used shows that for the radial position where solids holdup is higher (near the wall), the increase in solids concentration does not affect the mean free path of the particles, resulting in higher values of D ML than in the dilute region (core).

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study of gas–solids flow in a short CFB riser by statistical and chaotic deterministic analysis of optical fibre probe signals

Castilho

Cremasco

2012

Can J Chem Eng

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“…No entanto, um grande número de trabalhos que empregam a ciência do caos para modelar vários fenômenos vem sendo utilizada, como por exemplo, em diversas áreas da engenharia de processos: Ellis et al, 2003;Manyele et al, 2006;Wu et al, 2007; Ajbar et al, 2009;Wang et al, 2010;Cremasco et al, 2011 e Castilho, 2011. A maioria desses trabalhos baseia-se em dados escalares de séries temporais para descrever fenômenos complexos advindos de uma dinâmica não linear.…”

Section: Introductionunclassified

Utilização Da Análise De Caos No Processamento De Sinais: Discussão Sobre Propriedades Caóticas

Moura¹,

Castilho²,

Cremasco³

2015

Anais Do XXXVII Congresso Brasileiro De Sistemas Particulados

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RESUMOSinais caóticos são sinais cujo comportamento é aperiódico e sensível a condições iniciais ou a pequenas perturbações. Sob este aspecto, diversos campos do conhecimento, tais como engenharia, biologia, economia, podem fazer uso da análise de séries temporais para descrever situações características a seus estudos. Contudo, encontram-se dificuldades para classificar sistemas dinâmicos caóticos a partir de métodos tradicionais como, por exemplo, o espectro de potência de Fourier. Para uma nova abordagem, a reconstrução de atratores, a partir do método de Takens, vem sendo apontada como alternativa de análise para diferenciar o caos determinístico de um comportamento estocástico. A partir do caos determinístico, várias propriedades, conhecidas como invariantes caóticas, podem ser determinadas, como a dimensão de correlação (fractal) e a entropia de Kolmogorov. O presente trabalho objetiva discutir as principais propriedades envolvidas na análise de caos e aplicações na engenharia química, tendo como base a abordagem de conceitos sobre decomposição em sistema singulares (para reconstrução do espaço de fase); dimensão de imersão; comprimento da janela; dimensão de correlação e a entropia de Kolmogorov. INTRODUÇÃOMuitos dos fenômenos complexos observados em experimentos nas ciências exatas são modelados por conceitos de sistema estocásticos (análises estatísticas e análises no domínio da frequência) (FERRARA E PRADO, 1994). No entanto, um grande número de trabalhos que empregam a ciência do caos para modelar vários fenômenos vem sendo utilizada, como por exemplo, em diversas áreas da engenharia de processos: Ellis et al., 2003;Manyele et al., 2006;Wu et al., 2007; Ajbar et al., 2009;Wang et al., 2010;Cremasco et al., 2011 e Castilho, 2011. A maioria desses trabalhos baseia-se em dados escalares de séries temporais para descrever fenômenos complexos advindos de uma dinâmica não linear. Nestes casos, em que nem as relações matemáticas, nem as relações das variáveis que influenciam são conhecidas, a teoria do caos fornece uma alternativa para uma caracterização qualitativa (espaço de fase) e quantitativa (dimensão de correlação e entropia de Kolmogorov) superior à abordagem tradicional estocástica (JAYAWARDENA E GURUNG, 2000). Este trabalho tem por finalidade apresentar uma revisão da aplicação da teoria do caos na análise qualitativa e quantitativa de uma série temporal experimental. RECONSTRUÇÃO DO ESPAÇO DE FASEUmas das formas de reconstrução do espaço de fase a partir do teorema de Takens,

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A critical analysis of the acceleration length and pressure profile of single‐particle systems in a circulating fluidized bed

Das

Meikap

Saha

2008

Asia-Pacific J Chem Eng

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A study was conducted to explore the hydrodynamic behaviors using both Geldart group A and B materials in a circulating fluidized bed unit consisting of fast column (riser) of 0.1016 m i.d. and 5.62 m height. The materials tested were 120 µm of the fluid catalytic cracking (FCC) catalyst, 166 µm of iron ore, 215 µm of coal and five types of sand particles, ranging in size from 300 to 622 µm. The superficial air velocity ranged between 2.01 and 4.681 m/s and solid fluxes of 12.5-50 kg/m 2 s. Riser static pressure profiles were measured for the FCC catalyst, coal, iron ore and sand particles. Acceleration lengths were determined from the data, and using these and other data from the literature two correlations for the acceleration length were established for Geldart's group A and B particles. 

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Analysis of the chaotic dynamics of a high-flux CFB riser using solids concentration measurements

Cited by 13 publications

References 23 publications

Study of gas–solids flow in a short CFB riser by statistical and chaotic deterministic analysis of optical fibre probe signals

Study of gas–solids flow in a short CFB riser by statistical and chaotic deterministic analysis of optical fibre probe signals

Utilização Da Análise De Caos No Processamento De Sinais: Discussão Sobre Propriedades Caóticas

A critical analysis of the acceleration length and pressure profile of single‐particle systems in a circulating fluidized bed

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