A novel experimental method for determining lateral mixing of solids in fluidized beds – Quantification of the splash-zone contribution

Castilla, Guillermo Martinez; Larsson, Anton; Lundberg, Louise; Johnsson, Filip; Pallarès, David

doi:10.1016/j.powtec.2020.05.036

Cited by 18 publications

(9 citation statements)

References 30 publications

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“…In this way, the lateral dispersion of solids is enhanced. This finding is in accordance with the experimental results acquired by Castilla et al [16] and Liu and Chen [19].…”

Section: Lateral Mixing Quality Of Solidssupporting

confidence: 93%

“…However, it is quite confusing that the lateral dispersion coefficient reported in the literature differed by up to four orders of magnitude [14][15][16][17][18][19][20][21][22][23][24][25][26]. Even for fluidized beds operated in similar conditions, the difference between reported lateral dispersion coefficients may be up to two orders of magnitude.…”

Section: Introductionmentioning

confidence: 97%

“…Many experimental methods have been developed to derive the distribution of tracer particles in fluidized beds and fit the lateral mixing process by the diffusion equation to determine the lateral dispersion coefficient. Castilla et al [16] proposed a novel thermal experimental method which utilizes the finite volume analysis of the temperature field over the bed surface to determine the solids dispersion coefficient in a bubbling fluidized bed. The dispersion coefficients were in the order of 10 −3 m 2 /s.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Quantification of the Lateral Mixing of Binary Solids in Bubbling Fluidized Beds

Huang

Liu

et al. 2021

Energies

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A novel experimental method for the lateral mixing of binary solids in bubbling fluidized beds was developed based on the capacitance probe technique. The evolutions of local mixing ratios in a fluidized bed which can be assumed as one mixing cell were analyzed in detail. The solids mixing within one mixing cell was resolved and the effect of convection and diffusion mechanism on lateral mixing was evaluated individually. The results show that at lower part of the fluidized bed, convection plays a more important role in the mixing process near the wall; meanwhile, diffusion is very important for the mixing around the center line. This is opposite with that at the higher part. A lateral micro dispersion coefficient was proposed to characterize the lateral mixing within the mixing cell and the value is generally between 0.005 and 0.025 m/s. A new mixing index was proposed to evaluate the lateral mixing quality of binary solids. It was found that at the lower part of the fluidized bed, the best mixing is acquired at the half radius, whereas mixing at the center line is the worst. At the higher part, solid mixing is better when increasing the distance from the wall. The influences of gas velocity and static bed on the lateral mixing were also discussed from a microscopic perspective.

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“…In this way, the lateral dispersion of solids is enhanced. This finding is in accordance with the experimental results acquired by Castilla et al [16] and Liu and Chen [19].…”

Section: Lateral Mixing Quality Of Solidssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Quantification of the Lateral Mixing of Binary Solids in Bubbling Fluidized Beds

Huang

Liu

et al. 2021

Energies

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“…The analysis of factors influencing the process of fuel combustion in bubbling fluidized beds is the subject of the paper [19]. The thermographic camera measurements of temperature distribution in the fluidized bed were used to estimate the influence of key parameters of the process such as fluidization velocity, particle size, and pressure drop over the air distributor plate on the lateral mixing of bulk solids in bubbling fluidized beds.…”

Section: Introductionmentioning

confidence: 99%

“…The reason for this is the time needed to transfer the heat to a temperature sensor in a solid casing. The PID (proportional-integral-derivative) is the most commonly used controller in the industry and has been the dominant control technique for process control for many decades [18,19].…”

Section: Introductionmentioning

confidence: 99%

Influence of the Thermometer Inertia on the Quality of Temperature Control in a Hot Liquid Tank Heated with Electric Energy

et al. 2020

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This paper presents the medium temperature monitoring system based on digital proportional–integral–derivative (PID) control. For industrial thermometers with a complex structure used for measuring the temperature of the fluid under high pressure, the accuracy of the first-order model is inadequate. A second-order differential equation was applied to describe a dynamic response of a temperature sensor placed in a heavy thermowell (industrial thermometer). The quality of the water temperature control system in the tank was assessed when measuring the water temperature with a jacketed thermocouple and a thermometer in an industrial casing. A thermometer of a new design with a small time constant was also used to measure temperature. The quality of water temperature control in the hot water storage tank was evaluated using a classic industrial thermometer and a new design thermometer. In both cases, there was a K-type sheathed thermocouple inside the thermowell. Reductions in the time constant of the new thermometer are achieved by means of a steel casing with a small diameter hole inside which the thermocouple is precisely fitted. The time constants of the thermometers were determined experimentally with a jump in water temperature. A digital controller was designed to maintain the preset temperature in an electrically heated hot water tank. The function of the regulator was to adjust the power of the electrical heater to maintain a constant temperature of the liquid in the tank.

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Effective lateral dispersion of momentum, heat and mass in bubbling fluidized beds

Gustafsson,

Castilla,

Pallarès

et al. 2024

Front. Chem. Sci. Eng.

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The lateral dispersion of bed material in a bubbling fluidized bed is a key parameter in the prediction of the effective in-bed heat transfer and transport of heterogenous reactants, properties important for the successful design and scale-up of thermal and/or chemical processes. Computational fluid dynamics simulations offer means to investigate such beds in silico and derive effective parameters for reduced-order models. In this work, we use the Eulerian-Eulerian two-fluid model with the kinetic theory of granular flow to perform numerical simulations of solids mixing and heat transfer in bubbling fluidized beds. We extract the lateral solids dispersion coefficient using four different methods: by fitting the transient response of the bed to (1) an ideal heat or (2) mass transfer problem, (3) by extracting the time-averaged heat transfer behavior and (4) through a momentum transfer approach in an analogy with single-phase turbulence. The method (2) fitting against a mass transfer problem is found to produce robust results at a reasonable computational cost when assessed against experiments. Furthermore, the gas inlet boundary condition is shown to have a significant effect on the prediction, indicating a need to account for nozzle characteristics when simulating industrial cases.

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A novel experimental method for determining lateral mixing of solids in fluidized beds – Quantification of the splash-zone contribution

Cited by 18 publications

References 30 publications

Experimental Quantification of the Lateral Mixing of Binary Solids in Bubbling Fluidized Beds

Experimental Quantification of the Lateral Mixing of Binary Solids in Bubbling Fluidized Beds

Influence of the Thermometer Inertia on the Quality of Temperature Control in a Hot Liquid Tank Heated with Electric Energy

Effective lateral dispersion of momentum, heat and mass in bubbling fluidized beds

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