Oxidation reactivity and kinetic analysis of bituminous coal char from high-temperature pyrolysis: Effect of heating rate and pyrolysis temperature

Liu, Xing; Tan, Houzhang; Wang, Xuebin; Wang, Zhao; Xiong, Xiaohe

doi:10.1016/j.tca.2020.178660

Cited by 16 publications

(5 citation statements)

References 47 publications

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“…This relationship represents the mechanism of the reaction and will directly determine the shape of the TG curve. Its integral form is defined as 37:

true g (α) = \int_{0}^{α} \frac{1}{f (α)} normald α

…”

Section: Resultsmentioning

confidence: 99%

Non‐Isothermal Thermogravimetric Analysis Study on the Pyrolysis Reaction Kinetics of Bituminous Coal

Wang

et al. 2022

Chem Eng & Technol

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A kinetic analysis of the pyrolysis of bituminous coal is performed. The coal sample is pyrolyzed with a thermogravimetric analyzer, and the pyrolysis process at different heating rates is investigated. As the heating rate increases, the initial pyrolysis temperature and the peak temperature of the maximum weight loss rate tend to migrate to higher temperatures. The activation energy and pre‐exponential factor are calculated by a single first‐order reaction model using the Doyle integral method. The activation energies are estimated depending on the conversion rate. Furthermore, higher heating rates can lead to larger activation energy values in the initial pyrolysis stage.

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“…This relationship represents the mechanism of the reaction and will directly determine the shape of the TG curve. Its integral form is defined as 37:

true g (α) = \int_{0}^{α} \frac{1}{f (α)} normald α

…”

Section: Resultsmentioning

confidence: 99%

Non‐Isothermal Thermogravimetric Analysis Study on the Pyrolysis Reaction Kinetics of Bituminous Coal

Wang

et al. 2022

Chem Eng & Technol

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“…The characteristic temperature and time are calculated by the TG-DTG method. 48 The maximum and average mass loss rate are defined as (dW/dt) max and (dW/ dt) ave , respectively. The time duration of the mass loss rate above 0.5(dW/dt) max is abbreviated as Δt 1/2 .…”

Section: Resultsmentioning

confidence: 99%

“…The characteristic time of ignition, DTG peak, and burnout is abbreviated as t i , t p , and t f , respectively. The characteristic temperature and time are calculated by the TG-DTG method . The maximum and average mass loss rate are defined as (dW/d t ) max and (dW/d t ) ave , respectively.…”

Section: Resultsmentioning

confidence: 99%

Combustibility and Cofiring of Coal Gasification Fine Ash with High Carbon Content in a Full-scale Pulverized Coal Furnace

et al. 2020

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Coal gasification fine ash (CGFA) having a high carbon content is produced in large quantity as a byproduct from coal gasifiers in China. CGFA is usually disposed of by landfill as a solid waste, which is not only detrimental to environment but also a loss of an enormous energy that renders the process inefficient. Therefore, it is crucial to make use of the high carbon content in the CGFA with an economic and environmentally friendly method. In this study, the ignition and burnout behavior of CGFA were investigated via a thermogravimetric analyzer (TGA), flat-flame burner (FFB), and drop-tube furnace (DTF). Further, the cofiring of CGFA was numerically studied in a tangentially fired pulverized coal boiler burning anthracite with various cofiring ratios (0%, 10%, 20%, and 30%). The TGA results show the similar oxidation reactivity, oxidation kinetics, and ignition behavior of CGFA with the anthracite. In the FFB atmosphere with practical heating rates, the CGFA and anthracite are both heterogeneously ignited with an ignition time of 8.1 and 7.6 ms, respectively. The particle size significantly affected the ignition time of CGFA, as the particle size decreased from 125 to 135 μm to 45−63 μm and the ignition time of CGFA decreased from 10.1 to 5.6 ms. The burnout test in DTF indicates that the promising burnout performance in a pulverized coal furnace required a crucial oxygen concentration >10%, and the CFD simulation results coincided well with the experimental data from DTF. The CFD modeling results of the full-scale furnace show that the cofiring of CGFA is feasible in the pulverized coal furnace burning anthracite. Compared with the mode of pure anthracite combustion, under the cofiring mode with 10−30% CGFA as the energy input, the central maximum temperature of the main combustion zone increases by 50−90 °C, resulting in the slightly improved burnout for both anthracite and CGFA.

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“…The sample was heated from 30 to 950 • C at a constant rate of 10 • C min −1 under a nitrogen atmosphere with a flow rate of 100 mL min −1 . The ignition and burnout temperatures of CPW-1, CPW-2, and corresponding chars were calculated using the intersection and conversion methods [27].…”

Section: Thermal and Structural Analysismentioning

confidence: 99%

Torrefaction Upgrading of Heterogenous Wastes Containing Cork and Chlorinated Polymers

et al. 2022

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Torrefaction of two mixed wastes composed of cork and chlorinated polymers was studied at temperatures from 200 to 350 °C, for residence times of 30 and 60 min. These wastes were recovered from sandwich panels with cork core, have different contents of cork biomass and chlorinated polymers and present poor fuel properties for energy recovery applications. The raw wastes and the produced biochars were characterized for proximate and ultimate analysis, chlorine content, mineral composition, calorific value, mass yield, energy density, particle size distribution, and adsorption capacity towards cationic and anionic dyes. Torrefaction enabled the production of biochars with mass yields from 97.2 to 54.5%, with an increase in 12.1 to 37.9% in apparent density relative to the raw wastes, and HHV from 18.2 to 20.7 MJ/kg. Nevertheless, the chlorine content of the biochars was increased to values higher than 5%, inadequate for solid fuels. Dechlorination of the biochars by washing with hot water enabled 84 to 91% removal of the chlorine species achieving final concentrations lower than 1%, without significant reduction in the biochars calorific values. For the waste with higher polymer and ash content, the torrefaction process reduced the heating value; therefore, energy valorization was not adequate. Both the raw wastes and the biochars were tested as adsorbents for cationic and anionic dyes. After activation with KOH, both the raw materials and the biochars had removal efficiencies higher than 90% for methylene blue, a cationic dye often found in industrial effluents. The results showed that torrefaction combined with hot water washing converted these wastes to biochars with the potential for energy or material valorization contributing to a circular economy in the cork industrial sector.

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Oxidation reactivity and kinetic analysis of bituminous coal char from high-temperature pyrolysis: Effect of heating rate and pyrolysis temperature

Cited by 16 publications

References 47 publications

Non‐Isothermal Thermogravimetric Analysis Study on the Pyrolysis Reaction Kinetics of Bituminous Coal

Non‐Isothermal Thermogravimetric Analysis Study on the Pyrolysis Reaction Kinetics of Bituminous Coal

Combustibility and Cofiring of Coal Gasification Fine Ash with High Carbon Content in a Full-scale Pulverized Coal Furnace

Torrefaction Upgrading of Heterogenous Wastes Containing Cork and Chlorinated Polymers

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