Investigation on the lignite pyrolysis reaction kinetics based on the general Arrhenius formula

Lian, Wenhao; Wang, Junli; Wang, Guijing; Gao, Dan; Li, Xue; Zhang, Zhonglin; Huang, Wei; Hao, Xiaogang; Hou, Baolin

doi:10.1016/j.fuel.2020.117364

Cited by 28 publications

(11 citation statements)

References 38 publications

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“…Thermal analysis kinetics is a method to determine the reaction-related kinetic parameters by using thermal analysis technology based on the thermal analysis kinetic equation. It obeys Arrhenius law, 30 and its basic dynamic equation is 4 where β is the heating rate (°C/min), k is the reaction rate constant, α is the conversion rate (%), f (α) is the reaction mechanism function, and A is the pre factor, also known as pre factor or frequency factor (s –1 ).…”

Section: Methodsmentioning

confidence: 99%

Study on Combustion Kinetic Characteristics of Lignite and Semi-coking Dust

Sha

2022

ACS Omega

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In order to master the combustion kinetic characteristics of semi-coking dust in the early pyrolysis stage of lignite combustion explosion, a vacuum tube furnace was used to prepare semi-coking dust with different pyrolysis degrees, and the experimental samples were studied by a synchronous differential thermal analyzer. By means of theoretical analysis, the reaction mechanism of lignite and semi-coking dust was revealed. The results show that when the final pyrolysis temperature rises to 920 °C, the percentage of volatile matter decreases by 94.6%. The reaction in this process also causes the original pores to be cross-linked and collapsed, and a large number of new pores are generated, and the original pore structure is significantly enlarged. With the increase of the final temperature of pyrolysis, the ignition temperature ( T b ) of the dust increased from 354 to 455 °C, the fastest reaction temperature ( T c ) increased from 399 to 495 °C, and the ember temperature ( T d ) increased from 558 to 658 °C. The maximum combustion rate decreased by 65.97%, and the average combustion rate decreased by 84.67%. The apparent activation energy increased by 4.7 times from 45.219 to 257.665 kJ/mol, and the combustion kinetics of semi-coke became worse. The thermal reaction of lignite and semi-coking dust conforms to the diffusion mechanism of the three-dimensional spherical symmetry model. The research results provide a new idea for discussing the mechanism of coal dust explosion and the development of explosion suppression technology.

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Section: Methodsmentioning

confidence: 99%

Study on Combustion Kinetic Characteristics of Lignite and Semi-coking Dust

Sha

2022

ACS Omega

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Section: Mechanisms and Analysismentioning

confidence: 99%

“…According to preliminary experiments, in the same input energy, the peak temperature and peak pressure of microwave heating are higher than those of conventional heating methods, which reflects in that the rate of static crushing agent hydration reaction using the microwave heating method is higher than using conventional heating. According to the Arrhenius formula, increasing the temperature can increase the percentage of activated molecules, thus increasing the number of activated molecules, the effective collision between molecules, and the chemical reaction rate …”

Section: Mechanisms and Analysismentioning

confidence: 99%

“…According to the Arrhenius formula, increasing the temperature can increase the percentage of activated molecules, thus increasing the number of activated molecules, the effective collision between molecules, and the chemical reaction rate. 18 As shown in Figure 7, with the same energy input, the final temperature of the heating phase of microwave heating is higher than that of conventional heating, using the slope to indicate the heating rate of the two heating methods. The heating rate of microwave heating K 1 = 3.035, and the heating rate of conventional heating K 2 = 2.1.…”

Section: Mechanisms and Analysismentioning

confidence: 99%

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Mechanistic Study of a Microwave Field-Controlled Static Crushing Agent for Efficient Rock Breaking

Liu

Guan

et al. 2022

ACS Omega

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The long reaction time and uncontrollable reaction process of the swelling agent in the process of rock breaking by static crushing agent lead to unsatisfactory efficiency and effect of rock breaking. This paper uses physical experiments to compare and analyze the changes in temperature and pressure of the hydration reaction under different microwave conditions; utilizes microscopic analysis of the hydration reaction products under each condition, combined with numerical calculations to elucidate the mechanism of the effect of microwave field on the hydration reaction of the expansion agent; and proposes a microwave field-controlled static crushing agent rock-breaking method. The study reached the following main conclusions: (1) microwave heating is better than conventional heating in terms of heating rate, peak temperature, and peak pressure; (2) using static crushing agent rock breaking is preferable to use a low-power microwave field to control the reaction process, and to ensure that the initial temperature is not higher than the local water boiling point; (3) microwave heating to promote the reaction mechanism lies in its deep heating of the system, faster heating rate, and higher energy utilization, and is more conducive to hydration expansion reaction; (4) selective heating of microwaves can enhance the hydration reaction of calcium oxide and inhibit the production of hydrated tricalcium silicate, making the reaction more complete, while microwave heating will also improve the microstructure of hydration products.

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“…To analyze the reaction rate of coke gasification taking into consideration the spatial distribution of reactivity, the distributed activation energy model (DAEM), which is often used for the release of volatile matter from coal, − can be used because the change in carbon crystallinity by gasification and the spatial distribution of reactivity in coke cannot be neglected. The DAEM is a reaction model that expresses the distribution of activation energy when many different reactions, such as pyrolysis and oxidation of heavy oils, , occur simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Modeling of CO₂ and H₂O Gasification Reactions for Metallurgical Coke Using a Distributed Activation Energy Model

et al. 2021

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A distributed activation energy model (DAEM) was applied to the kinetic analysis of CO 2 and H 2 O gasification reactions for pulverized metallurgical coke. The results of the scanning electron microscopy observations and CO 2 gas adsorption suggested that the gasification reaction occurs at the particle surface. Therefore, a grain model was employed as a gasification reaction model. The reaction rates of CO 2 and H 2 O gasification were evaluated based on the DAEM. The activation energy changed as the reaction progressed and hardly depended on the particle size. The activation energies were 200–260 kJ/mol in CO 2 gasification and 220–290 kJ/mol in H 2 O gasification. The frequency factor of H 2 O gasification was approximately 10 times larger than that of CO 2 gasification, regardless of the progress of the reaction. At the same activation energy level, the frequency factor showed a higher value with a decrease in the particle size. This result was consistent with the theory of the grain model and indicated that the gasification reaction of the pulverized coke with a micrometer scale occurs on the surface of the coke particle. Furthermore, the value predicted by the DAEM was in good agreement with the experimental one.

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Investigation on the lignite pyrolysis reaction kinetics based on the general Arrhenius formula

Cited by 28 publications

References 38 publications

Study on Combustion Kinetic Characteristics of Lignite and Semi-coking Dust

Study on Combustion Kinetic Characteristics of Lignite and Semi-coking Dust

Mechanistic Study of a Microwave Field-Controlled Static Crushing Agent for Efficient Rock Breaking

Kinetic Modeling of CO₂ and H₂O Gasification Reactions for Metallurgical Coke Using a Distributed Activation Energy Model

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Investigation on the lignite pyrolysis reaction kinetics based on the general Arrhenius formula

Cited by 28 publications

References 38 publications

Study on Combustion Kinetic Characteristics of Lignite and Semi-coking Dust

Study on Combustion Kinetic Characteristics of Lignite and Semi-coking Dust

Mechanistic Study of a Microwave Field-Controlled Static Crushing Agent for Efficient Rock Breaking

Kinetic Modeling of CO2 and H2O Gasification Reactions for Metallurgical Coke Using a Distributed Activation Energy Model

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Product

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Kinetic Modeling of CO₂ and H₂O Gasification Reactions for Metallurgical Coke Using a Distributed Activation Energy Model