Dynamic Elemental Thermal Analysis: A technique for continuous measurement of carbon, hydrogen, oxygen chemistry of tar species evolved during coal pyrolysis

Stanger, Rohan; Xie, Wei; Wall, Terry; Lucas, John; Mahoney, Merrick R.

doi:10.1016/j.fuel.2012.06.071

Cited by 17 publications

(11 citation statements)

References 23 publications

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“…The oxygen content in tar of HM–hematite and HM–specularite was lower than in that of HM at the final temperature of 600 °C.When the added hematite proportion was 20%, the oxygen content in the HM–hematite tar decreased to 8.70%, and the H/C ratio increased by 0.36% while the O/C ratio decreased from 0.14% to 0.08% compared with the results of the HM; the oxygen removal ratio reached 36.89%. This indicated that the stability and the utilization value of the pyrolysis tar had been improved. , In addition, when the added specularite proportion was 20%, the oxygen in the produced tar was removed and its content decreased to 7.83% compared with 13.78% of HM; it thus had a greater deoxidization effect than HM, and the oxygen removal ratio reached 43.16%. Overall, the specularite showed a stronger ability to remove O from pyrolysis tar.…”

Section: Resultsmentioning

confidence: 96%

Effects of Iron Ores on the Pyrolysis Characteristics of a Low-Rank Bituminous Coal

Zhao

et al. 2016

Energy Fuels

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This work investigates the effects of two kinds of iron ore on the pyrolysis characteristics of a low-rank bituminous coal from Hami, China. The pyrolysis and its product distribution were studied using a thermogravimetric analyzer and a fixed bed reactor. A gas chromatograph and a gas chromatograph–mass spectrometer were employed to test the properties and composition of the pyrolytic products. Results showed that the pyrolysis temperature of the raw coal ranged mainly from 350 to 650 °C. The weight-loss rate reached a maximum of 6.95%/min at 443 °C. The weight loss was 44.27% at the final pyrolysis temperature of 750 °C. The tar yield of raw coal was 9.51% in the fixed bed reactor at 600 °C. Adding iron ore, which was intended for a lower tar yield and a higher fraction of light tar (boiling point <360 °C), had a catalytic effect on the pyrolysis of raw coal. With separate addition of hematite and specularite, both having a mass of 20% of the raw coal, coal weight loss increased by 3.86% and 5.56%, respectively, when the catalytic upgrading was at 600 °C, and good upgrading effect was obtained. Meanwhile, benzene homologue in tar increased slightly, by 0.62% and 1.44%, compared to that in the tar of the raw coal. The upgrading effects of iron ore on tar also lowered element O content in the resulting tar, by 36.89% with the addition of hematite and by 43.16% with specularite. The iron concentrate recovered was measured by magnetic separation method. The iron concentrate grade was 52.97% with hematite added in coal when the residence time of ultimate pyrolysis temperature was 25 min and the magnetic field strength was 96.48 kA/m, while it was 58.02% with specularite added when the residence time was 35 min and the magnetic field strength was 109.27 kA/m, both with a char grinding fineness of less than 0.074 mm (ground char accounting for approximately 80% of total char); iron concentrate recovery rate was 85.31% and 76.74%, respectively. The experimental results proved the feasibility of recovering iron ore in char by magnetic separation.

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Section: Resultsmentioning

confidence: 96%

Effects of Iron Ores on the Pyrolysis Characteristics of a Low-Rank Bituminous Coal

Zhao

et al. 2016

Energy Fuels

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“…DETA analyses were conducted in duplicate with the deviation between runs was found to be <3%. Details of DETA working principle can be found elsewhere. ,, …”

Section: Methodsmentioning

confidence: 99%

“…Details of DETA working principle can be found elsewhere. 32,35,36 2.2.4. Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.…”

Section: Experimental Techniques 221 Computer Aided Thermalmentioning

confidence: 99%

Impacts of Mild Pyrolysis and Solvent Extraction on Coking Coal Thermoplasticity

et al. 2016

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The thermoplastic development of a coking coal was studied before and after treatment to study the impacts on thermoswelling and volatiles release. The treatment process consisted of two consecutive steps, namely mild pyrolysis and solvent extraction. The intention was to characterize the thermally generated and solvent extractable material produced immediately prior to swelling onset and to study the impact of its removal. The heating step removed ∼5% of the coal volatiles and reduced its swelling extent from 83% to 25%. Subsequent solvent extraction with tetrahydrofuran (THF) on the heated coal removed up to 21% of material on a dry basis. The residue after extraction showed little swelling extent and significantly altered volatiles release profile on heating, indicating the role of extracted materials in thermoplastic development and tar formation. The molecular weight distributions of volatile tars collected after pyrolysis shared a similar molecular weight distribution spanning between 200 and 600 Da and peaking at ∼347 Da. By comparison, the molecular weight distribution of the THF extract peaked at ∼472 Da and extended to ∼3000 Da. In addition, it consisted of two classes of compounds: one covered the molecular weight range of tars with repeating structures every 12–14 Da up to 600 Da and the other contained 24 Da reoccurring units at molecular weight above 600 Da.

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“…The complexity of the coal structure results in a complexity of its reactions, which limits the development of coal thermal conversion processes. Coal structures have been studied using a variety of chemical methods, such as proximate analysis, elemental analysis, and solvent extraction . Coal samples and resultant fragments or products have been characterized by spectral or chromatographic methods, , such as infrared (IR) spectroscopy, nuclear magnetic resonance (NMR), X-ray diffractometry, and gas chromatography–mass spectrometry (GC–MS). , However, these methods provide only partial or empirical structures, or derive molecular structures from a fragment of the macromolecular structure of coal.…”

Section: Introductionmentioning

confidence: 99%

Theoretical and Experimental Insight into Coal Structure: Establishing a Chemical Model for Yuzhou Lignite

Wang

Guo

et al. 2016

Energy Fuels

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Because of their complex supermolecular structure, coal structures are challenging. We have tried to establish a novel method to construct a three-dimensional chemical model with proper reactivity for Yuzhou lignite using experimental and theoretical methods. Structural units of the Yuzhou lignite were built using elemental analysis, infrared analysis, 13 C nuclear magnetic resonance spectra, and density functional theory calculation. A three-dimensional chemical model was built in a periodic box in order to rationalize intra-and intermolecular interactions. To confirm the validity of the proposed model, we compared bond cracking pathways occurring during pyrolysis experiments using thermal gravimetric analysis and numerical dynamic reactive simulations employing the ReaxFF of thermal cracking of the model that we proposed. Experimental and numerical simulations results agreed, validating our building procedure. Therefore, this model could reflect both the basic structural characteristics and the thermal reactivity of Yuzhou lignite.

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Dynamic Elemental Thermal Analysis: A technique for continuous measurement of carbon, hydrogen, oxygen chemistry of tar species evolved during coal pyrolysis

Cited by 17 publications

References 23 publications

Effects of Iron Ores on the Pyrolysis Characteristics of a Low-Rank Bituminous Coal

Effects of Iron Ores on the Pyrolysis Characteristics of a Low-Rank Bituminous Coal

Impacts of Mild Pyrolysis and Solvent Extraction on Coking Coal Thermoplasticity

Theoretical and Experimental Insight into Coal Structure: Establishing a Chemical Model for Yuzhou Lignite

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