Low temperature oxidation and its kinetics of cornstalk chars

Fan, Penghui; Fan, Shuang; Sheng, Changdong

doi:10.1016/j.fuel.2016.04.072

Cited by 8 publications

(17 citation statements)

References 40 publications

(98 reference statements)

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“…Additionally, an evident shoulder is present attaching to the low temperature side of the first peak. The profile is similar to those observed from TGA of the combustion characteristics of herbaceous biomass including rice straw. − The shoulder and its overlapping part with the first peak is due to the devolatilization of the extractives and hemicellulose; the first and strongest peak is attributed to the devolatilization of cellulose and the oxidation of its volatiles, and the two peaks at higher temperatures are related to char oxidation catalyzed by inorganic matter …”

Section: Resultssupporting

confidence: 71%

Self-Heating of Agricultural Residues During Storage and Its Impact on Fuel Properties

2017

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The present work aimed to investigate the self-heating process of agricultural residues during storage and to evaluate its impact on the properties of the stored fuels. Two types of biomass, rice straw and husk, were used as raw materials. Their self-heating processes and characteristics were investigated by storing the materials with different moisture contents and particle sizes in a bench-scale reactor and monitoring the evolution of inside temperatures. The resulting materials were systematically characterized. Comparison of the composition, calorific value, pH value, surface structure, and combustion characteristics between the initial and stored materials were performed to assess the influence of moderate self-heating on the fuel properties. Observations on the evolution of the temperatures inside stored materials showed that the characteristics of the self-heating process including the induction time, period with significant heat generation, and peak temperature as well as the hottest position within the sample depend upon biomass type, initial moisture content, and particle size of the sample. Characterization of fuel properties showed that moderate self-heating during storage slightly changed the proximate composition of dry biomass but resulted in considerable losses of dry matter and energy as well as a slight increase in the fuel combustion reactivity. The higher moisture contents and smaller particle size benefit self-heating. Rice straw is more prone to self-heating than rice husk under the same conditions, as reflected by the higher extent of the self-heating and the more dry matter and energy losses.

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Section: Resultssupporting

confidence: 71%

Self-Heating of Agricultural Residues During Storage and Its Impact on Fuel Properties

2017

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“…This results in an unsteady thermal power evolution: ,, the power initially increases rapidly to a peak and then gradually declines with time mostly due to O 2 depletion in the ampule . In such a case, the peak power, − the power at a certain time or conversion, or cumulative heat release until a certain time ,,,, may be taken as the characteristic for evaluating self-heating reactivity due to chemical oxidation.…”

Section: Low Temperature Chemical Oxidationmentioning

confidence: 99%

“…IC has been applied to assess the heat generation characteristics of low temperature chemical oxidation of various biomass materials. ,,,− It was used to determine the reactivity of fuel pellets and significant differences between different types of pellets were found. Accordingly, a screening test procedure was proposed, measuring the heat production at typical bulk storage temperatures and using the resulting maximum power or cumulative heat to rank the self-heating potential of the pellets for safe storage.…”

Section: Low Temperature Chemical Oxidationmentioning

confidence: 99%

“…Lumping the exothermic reactions as a global one following the Arrhenius law, , the heat release rate, q (W), is expressed as where m is the mass of the sample (kg). Rearranging the expression allows use of the Arrhenius plot to derive the kinetic parameters, The heat release rate q is taken to be the measured steady heat power, the peak power, or the power at a certain time or conversion ,, at each temperature.…”

Section: Low Temperature Chemical Oxidationmentioning

confidence: 99%

“…The kinetics can also be derived from the non-steady-state data recorded during the tests. The method was proposed by Willson et al and had been applied for kinetic analysis of self-heating of biomass char and wood pellets . Assuming the overall oxidation to be first-order with respect to oxygen, the heat power is expressed as where k is the reaction rate constant (1/s) with an Arrhenius form, N is the moles of O 2 initially sealed in the ampule (mol), H is the cumulative heat release (J), and Δ H is the heat of reaction (J/(mol O 2 )).…”

Section: Low Temperature Chemical Oxidationmentioning

confidence: 99%

See 2 more Smart Citations

Review on Self-Heating of Biomass Materials: Understanding and Description

Sheng

Yao

2022

Energy Fuels

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Storage of bulk biomass materials is essential along the feedstock supply chain of bioenergy production. The self-heating accompanying biomass storage has hazardous consequences. With the increasing biomass utilization for bioenergy production, the risk and economic and environmental concerns about biomass storage have been attracting extensive research attention aimed at understanding the processes of heat generation, evaluating the propensity of a material to self-heating and spontaneous ignition, describing and predicting the self-heating process and consequences in biomass storage, and developing strategies and technologies for storage management. The advances in the understanding and description of heat generation processes including water-associated physical processes, microbiological degradation processes, and chemical oxidative processes during the self-heating in biomass storage are reviewed, with the focus on understanding the processes and their underlying mechanisms, reaction kinetics, and heats of reaction through experimental studies and description of heat generation and self-heating processes through kinetic analyses and modeling. This review highlights the need to improve the mechanistic model description of the self-heating processes and associated material changes and product formation, which demand a better understanding and description of microbial degradation and chemical oxidation through experimental study.

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Kinetic analysis on low‐temperature oxidation of wood pellets by isothermal microcalorimetry

Yao,

Sheng

2024

Fire and Materials

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Low‐temperature chemical oxidation is the major driver of self‐heating during storage of wood pellets and its kinetics is essential to describe the heat evolution. In the present work, isothermal microcalorimetry was used to characterize heat generation behavior of three types of wood pellets (pine, fir, and redwood pellets) at 30–70°C. The obtained data were employed to derive the kinetics of low‐temperature oxidation by the peak power, iso‐conversional method, and non‐steady analysis. The consistency and applicability of the kinetics derived by the three methods were evaluated. Kinetic parameters determined by the peak power method were observed to match those from the iso‐conversional method at lower conversions of the oxidation for heat generation. The kinetics derived by the iso‐conversional method indicated the oxidation reactivity generally decreasing and activation energy increasing with the conversion because of O2 consumption and reaction mechanism changing. With the impact of O2 consumption considered separately, the kinetics from the non‐steady analysis is capable of describing the evolution of heat power with the conversion and also consistent with that from the peak power method in describing intrinsic reactivity of pellet materials. The kinetics from the peak power and iso‐conversional methods lump the impact of O2 concentration with the reaction reactivity, suggesting their applications requiring additional models for connecting with O2 consumption.

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Low temperature oxidation and its kinetics of cornstalk chars

Cited by 8 publications

References 40 publications

Self-Heating of Agricultural Residues During Storage and Its Impact on Fuel Properties

Self-Heating of Agricultural Residues During Storage and Its Impact on Fuel Properties

Review on Self-Heating of Biomass Materials: Understanding and Description

Kinetic analysis on low‐temperature oxidation of wood pellets by isothermal microcalorimetry

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