Hydrothermal carbonization of millet stalk and dilute-acid-impregnated millet stalk: combustion behaviors of hydrochars by thermogravimetric analysis and a novel mixed-function fitting method

Dong, Xiaofeng; Guo, Shuqing; Ma, Minyang; Zheng, Huifan; Gao, Xinjie; Wang, Shuzhong; Zhang, Hengrui

doi:10.1016/j.fuel.2020.117734

Cited by 22 publications

(4 citation statements)

References 38 publications

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“…The fit quality for a given group of experiments is characterized by the root mean square of the corresponding relative deviations. For example, the root-mean-square reldev for 18 experiments is denoted by reldev 18 .…”

Section: Samples and Methodsmentioning

confidence: 99%

“…The second column is the degree of polynomial in the given evaluations. It is followed by the root-mean-square fit quality calculated for all of the 18 experiments, reldev 18 . One E value was obtained for each sample in this way, hence six E values were obtained for the six charcoals.…”

Section: Charcoal Combustionmentioning

confidence: 99%

“…The combustion of lignocellulosic materials is a particularly complex process because it involves thermal decomposition of several organic compounds and the decomposition is followed by the burn-off of the formed chars. The studies based on more than one kinetic equation usually employ a least-squares evaluation, which allows the determination of the model parameters and ensures the fit between the experimental data and the data calculated from the model. − Another branch of the studies is based on much simpler isoconversional methods. − In these works, the activation energy, E , and the pre-exponential factor, A , are regarded as functions of the reacted fraction, α, and the combustion is described by an equation of type where A (α), f (α), and E (α) are empirical functions. Obviously, only the product of A (α) and f (α) can be determined from the experimental data.…”

Section: Introductionmentioning

confidence: 99%

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Empirical Kinetic Models for the Combustion of Charcoals and Biomasses in the Kinetic Regime

2020

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An empirical kinetic model was proposed in 2019 and tested extensively on biomass pyrolysis (Vaŕhegyi, G., Energy Fuels 2019, 33, 2348−2358. The model was based on an isoconversional kinetic equation. The functions in the kinetic equation were approximated by mathematical formulas with adjustable parameters, and the parameters were determined by the method of least squares. This procedure ensures that the data calculated from the model would be close to the experimental data. In the present work, this way of modeling was adapted for the combustion of charcoals and lignocellulosic biomasses. The performance of the model was tested by the reevaluation of TGA experiments from earlier publications. In total, 18 experiments belonged to a study of charcoals, while 20 experiments were carried out on wheat straw and willow samples. The corresponding temperature programs included linear, modulated, stepwise, and constant reaction rate (CRR) temperature−time functions. The adjustable parameters of the model were determined by the method of least squares by evaluating groups of experiments together. The procedure aimed at finding best-fitting models for the derivative of the measured reacted fraction. The activation energy, E, was regarded as constant for the whole process. The change of the reactivity during the progress of the reaction was described by the rest of the isoconversional kinetic equation. Model variants with different numbers of adjustable parameters resulted in practically identical E values. It was possible to determine common E values for different samples with only a slight worsening of the fit quality. This procedure allowed an easy comparison of the reactivities of the samples as functions of the reacted fraction.

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Section: Samples and Methodsmentioning

confidence: 99%

Section: Charcoal Combustionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Empirical Kinetic Models for the Combustion of Charcoals and Biomasses in the Kinetic Regime

2020

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“…The T b referred to the temperature when the maximum weight loss rate was 1%/min. The peak temperature ( T m ) was defined as the temperature for the maximum value of the weight loss rate at the DTG curve [ 26 , 28 ].…”

Section: Experiments and Methodsmentioning

confidence: 99%

Co-hydrothermal carbonization of sewage sludge and coal slime for clean solid fuel production: a comprehensive assessment of hydrochar fuel characteristics and combustion behavior

Yang

Wang

Guo

et al. 2022

Biomass Conv. Bioref.

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The fuel characteristics and combustion behavior of the hydrochar obtained from the co-hydrothermal carbonization (co-HTC) of sewage sludge (SS) and coal slime (CS) were investigated. The results showed that a synergistic effect existed during the co-HTC process of SS and CS, which could make the mass yield, high heating value, carbon retention rate, energy recovery efficiency, fuel ratio, and energy balance of the hydrochar increase by 1.87–6.52%, 4.04–17.54%, 7.52–16.80%, 4.20–19.59%, 7.58–25.45%, and 35.26–40.08%, respectively. Furthermore, thermogravimetric and derivative thermogravimetry analysis indicated that the weight loss of co-hydrochar was significantly increased with increasing of CS ratio, and it was 38.39%, 48.14%, and 58.08% when the CS ratio was 25%, 50%, and 75% respectively. Adding CS during HTC could significantly improve the combustion performance of the hydrochar. Moreover, SS and CS were efficiently converted into solid fuels with better combustion performance and reactivity. Graphical Abstract

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Emerging Technologies in Millet Processing

Mazumdar

Durgalla

Akhila

2022

Handbook of Millets - Processing, Quality, and Nutrition Status

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Hydrothermal carbonization of millet stalk and dilute-acid-impregnated millet stalk: combustion behaviors of hydrochars by thermogravimetric analysis and a novel mixed-function fitting method

Cited by 22 publications

References 38 publications

Empirical Kinetic Models for the Combustion of Charcoals and Biomasses in the Kinetic Regime

Empirical Kinetic Models for the Combustion of Charcoals and Biomasses in the Kinetic Regime

Co-hydrothermal carbonization of sewage sludge and coal slime for clean solid fuel production: a comprehensive assessment of hydrochar fuel characteristics and combustion behavior

Emerging Technologies in Millet Processing

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