Improvement of continuous solid circulation rate measurement in a cold flow circulating fluidized bed

Ludlow, J. Christopher; Monazam, Esmail R.; Shadle, Lawrence J.

doi:10.1016/j.powtec.2007.06.031

Cited by 45 publications

(28 citation statements)

References 7 publications

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“…One of the applications of CFB in gasification processes is heating bed materials by combustion of fuels and then transporting them to the gasification reactor (Pfeifer et al, 2009). Fluid dynamic properties of the reactor, including gas-particle mixing and residence time, depend on the gas velocity and particle circulation rate for a given bed inventory (Ludlow et al, 2008). Gas velocity and bed material circulation rate are significant parameters determining the performance of the reactor.…”

Section: Introductionmentioning

confidence: 99%

Circulating fluidized bed combustion reactor: Computational Particle Fluid Dynamic model validation and gas feed position optimization

Thapa

Frohner

Tondl

et al. 2016

Computers & Chemical Engineering

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a b s t r a c tA 3D Computational Particle Fluid Dynamic (CPFD) model is validated against experimental measurements in a lab-scale cold flow model of a Circulating Fluidized Bed (CFB). The model prediction of pressure along the riser, downcomer and siphon as well as bed material circulation rates agree well with experimental measurements. Primary and secondary air feed positions were simulated by varying the positions along the height of the reactor to get optimum bed material circulation rate. The optimal ratio of the height of primary and secondary air feed positions to the total height of the riser are 0.125 and 0.375 respectively. The model is simulated for high-temperature conditions and for reacting flow including combustion reactions. At the high temperature and reaction conditions, the bed material circulation rate is decreased with the corresponding decrease in pressure drop throughout the CFB for the given air feed rate.

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Section: Introductionmentioning

confidence: 99%

Circulating fluidized bed combustion reactor: Computational Particle Fluid Dynamic model validation and gas feed position optimization

Thapa

Frohner

Tondl

et al. 2016

Computers & Chemical Engineering

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“…ε b = 0.45). This assumption was verified by using the mass balance methods prescribed by Ludlow et al [7] and the overall mean relative error was estimated to be 8% for these packed bed standpipe operation.…”

Section: Experimental Methodsmentioning

confidence: 78%

“…The mass circulation rate was continuously recorded by measuring the rotational speed of a twisted spiral vane located in the packed region of the standpipe as described by Ludlow et al [7]. This calibrated volumetric measurement was converted to a mass flux using the measured packed bed density presented in Table 1 and assuming that the packed bed void fraction at the point of measurement was constant (i.e.…”

Section: Experimental Methodsmentioning

confidence: 99%

Estimate of solid flow rate from pressure measurement in circulating fluidized bed

2010

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A method is described to estimate solid mass flow rate based on measurement of pressure drop in horizontal section of circulating fluid bed (CFB). A theoretical model was derived based on momentum balance equation and used to predict the solids flow rate. Several approaches for formulating such models are compared and contrasted. A correlation was developed that predicts the solids flow rate as a function of pressure drop measured in the horizontal section of piping leading from the top of the riser to the cyclone, often referred to as the cross-over. Model validation data was taken from literature data and from steady state, cold flow, CFB tests results of five granular materials with various sizes and densities in which the riser was operated in core-annular and dilute flow regimes. Experimental data were taken from a 0.20 m ID crossover piping and compared to literature data generated in a 0.10 m ID cross-over pipe. The solids mass flow rate data were taken from statistically designed experiments over a wide range of Froude number U 2 g gD ; 25-200 , load ratio Gs ρg Ug ; 0:2-23 , Euler number 2ΔP Horiz ρg U 2 g ; 2-50 , density ratio ρp −ρg ρg ; 60-2000 , Reynolds number ρg Ug dp μg ; 60-1600 , and Archimedes number ρs −ρg ð Þρgd 3 p μ 2 g ; 29-9500 ! . Several correlations were developed and tested to predict the solids mass flux based on measuring pressure drop in the horizontal section of CFB. It was found that load ratio G s ρ g U g is a linear function of the Euler number 2ΔP Horiz ρ g U 2 g! and that each of these expressions all worked quite well (R 2 N 95%) for the data within the range of conditions from which the coefficients were estimated. Published by Elsevier B.V.

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“…In direct method, direct collection of entrained solids is employed [9]. On the other hand, there are various options available on indirect methods such as using tracer particles [14], installing solid-velocity measuring device [15], using optical sensor [16], measuring pressure drop in circulation loop [17] and measuring bed pressure drop with its initial response curve [11]. Method [11] has been adopted due to its simplicity and reliability.…”

Section: Solid Circulation Rate Determinationsmentioning

confidence: 99%

Optimization of Solid Circulation Rate in Compartmented Fluidized Bed Gasifier for Power Generation

Chok¹,

Wee²,

Ariffin³

et al. 2008

AIP Conference Proceedings

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Abstract:The present paper reports the optimization of solid circulation rate (SCR) in Compartmented Fluidized Bed Gasifier (CFBG), an indirectly heated fluidized bed that incorporates two sets of v-valves and risers to control the solid circulation across the two compartments, i.e. combustor and gasifier of a pilot plant scale (the height and ID are 1.8m and 0.66m respectively). Sand was used as inert fluidized by air. Four operating variables were studied i.e. bed height, riser, v-valve and main bed flowrate. Based on 2 4 full factorial design of experiment in Yates' algorithm, at confidence level ≥ 95%, ANOVA analysis has revealed six important effects. The steepest ascent method was applied on linear regression generated from these effects to design the subsequent optimization experiments. The optimum values of SCR have been estimated for both low and high bed level at specific operating parameters.

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Improvement of continuous solid circulation rate measurement in a cold flow circulating fluidized bed

Cited by 45 publications

References 7 publications

Circulating fluidized bed combustion reactor: Computational Particle Fluid Dynamic model validation and gas feed position optimization

Circulating fluidized bed combustion reactor: Computational Particle Fluid Dynamic model validation and gas feed position optimization

Estimate of solid flow rate from pressure measurement in circulating fluidized bed

Optimization of Solid Circulation Rate in Compartmented Fluidized Bed Gasifier for Power Generation

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