00/00406 Simulation of char combustion according to shrinking particle and shrinking core model in circulating fluidized bed boilers

2000 ◽  
Vol 41 (1) ◽  
pp. 42
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Core Model ◽  
Shrinking Core Model ◽  
Char Combustion ◽  
Shrinking Core ◽  
Fluidized Bed Boilers

scholarly journals Correction to An Unreacted Shrinking Core Model Serves for Predicting Combustion Rates of Organic Additives in Clay Bricks

2021 ◽  
Vol 35 (5) ◽  
pp. 4616-4616
Author(s):  
Florian Wesenauer ◽  
Christian Jordan ◽  
Mario Pichler ◽  
Aron Frei ◽  
Mudassar Azam ◽  
...  
Keyword(s):  
Core Model ◽  
Shrinking Core Model ◽  
Organic Additives ◽  
Clay Bricks ◽  
Shrinking Core

Mesopores inside electrode particles can change the Li-ion transport mechanism and diffusion-induced stress

2010 ◽  
Vol 25 (8) ◽  
pp. 1433-1440 ◽  
Author(s):  
Stephen J. Harris ◽  
Rutooj D. Deshpande ◽  
Yue Qi ◽  
Indrajit Dutta ◽  
Yang-Tse Cheng
Keyword(s):  
Core Model ◽  
Published Data ◽  
Shrinking Core Model ◽  
Stress Distributions ◽  
Active Electrode ◽  
Free Surfaces ◽  
Surface Cracking ◽  
Active Particles ◽  
Shrinking Core ◽  
And Diffusion

Following earlier work of Huggins and Nix [Ionics6, 57 (2000)], several recent theoretical studies have used the shrinking core model to predict intraparticle Li concentration profiles and associated stress fields. A goal of such efforts is to understand and predict particle fracture, which is sometimes observed in degraded electrodes. In this paper we present experimental data on LiCoO2 and graphite active particles, consistent with previously published data, showing the presence of numerous internal pores or cracks in both positive and negative active electrode particles. New calculations presented here show that the presence of free surfaces, from even small internal cracks or pores, both quantitatively and qualitatively alters the internal stress distributions such that particles are prone to internal cracking rather than to the surface cracking that had been predicted previously. Thus, the fracture strength of particles depends largely on the internal microstructure of particles, about which little is known, rather than on the intrinsic mechanical properties of the particle materials. The validity of the shrinking core model for explaining either stress maps or transport is questioned for particles with internal structure, which includes most, if not all, secondary electrode particles.

scholarly journals Modelling of dynamics of combustion of biomass in fluidized beds

2004 ◽  
Vol 8 (2) ◽  
pp. 107-126 ◽  
Author(s):  
Jaakko Saastamoinen
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Fuel Mixture ◽  
Linear Increase ◽  
Fuel Feed ◽  
New Process ◽  
Fuel Particles ◽  
The Stability ◽  
Fluidized Bed Boilers

New process concepts in energy production and biofuel, which are much more reactive than coal, call for better controllability of the combustion in circulating fluidized bed boilers. Simplified analysis describing the dynamics of combustion in fluidized bed and circulating fluidized bed boilers is presented. Simple formulas for the estimation of the responses of the burning rate and fuel inventory to changes in fuel feeding are presented. Different changes in the fuel feed, such as an impulse, step change, linear increase and cyclic variation are considered. The dynamics of the burning with a change in the feed rate depends on the fuel reactivity and particle size. The response of a fuel mixture with a wide particle size distribution can be found by summing up the effect of different fuel components and size fractions. Methods to extract reaction parameters form dynamic tests in laboratory scale reactors are discussed. The residence time of fuel particles in the bed and the resulting char inventory in the bed decrease with increasing fuel reactivity and differences between coal and biomass is studied. The char inventory affects the stability of combustion. The effect of char inventory and oscillations in the fuel feed on the oscillation of the flue gas oxygen concentration is studied by model calculation. A trend found by earlier measurements is explained by the model.

scholarly journals Macerals of Shengli Lignite in Inner Mongolia of China and Their Combustion Reactivity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Ying Yue Teng ◽  
Yu Zhe Liu ◽  
Quan Sheng Liu ◽  
Chang Qing Li
Keyword(s):  
Activation Energy ◽  
Homogeneous Model ◽  
Optical Microscope ◽  
Core Model ◽  
Shrinking Core Model ◽  
Compact Structure ◽  
Shrinking Core ◽  
Combustion Reactivity ◽  
Combustion Processes ◽  
Kinetics Of

The macerals, including fusinitic coal containing 72.20% inertinite and xyloid coal containing 91.43% huminite, were separated from Shengli lignite using an optical microscope, and their combustion reactivity was examined by thermogravimetric analysis. Several combustion parameters, including ignition and burnout indices, were analyzed, and the combustion kinetics of the samples were calculated by regression. Fusinitic coal presented a porous structure, while xyloid coal presented a compact structure. The specific surface area of fusinitic coal was 2.5 times larger than that of xyloid coal, and the light-off temperature of the former was higher than that of the latter. However, the overall combustion reactivity of fusinitic coal was better than that of xyloid coal. The combustion processes of fusinitic and xyloid coals can be accurately described by both the homogeneous model and the shrinking core model. The features of xyloid coal agree with the shrinking core model when its conversion rate is 10%–90%. The activation energy of fusinitic coal during combustion can be divided into three phases, with the middle phase featuring the highest energy. The activation energy of xyloid coal is lower than that of fusinitic coal in the light-off phase, which may explain the low light-off temperature of this coal.

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