Coal Characterization in Relation to Coal Combustion

Jüntgen, H.

doi:10.1007/978-94-009-3661-4_1

Cited by 9 publications

(9 citation statements)

References 23 publications

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“…As a result of this, the formation of tar is depressed with increasing pressure up to 5 MPa. Tar compounds from degradation of macromolecules are only generated at higher temperatures, as indicated in a previous study (Jüntgen, 1987).…”

Section: Resultsmentioning

confidence: 95%

Influence of Experimental Conditions on Product Distribution During Pyrolysis of Tuncbilek Lignite (Turkey) at Low Heating Rates

2004

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Section: Resultsmentioning

confidence: 95%

Influence of Experimental Conditions on Product Distribution During Pyrolysis of Tuncbilek Lignite (Turkey) at Low Heating Rates

2004

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“…In general, coal is envisaged to have a macromolecular network structure which consists of chains of aromatic and hydro-aromatic structures cross-linked with aliphatic and ether bridges. [4][5][6][7][8][9][10] The coal network is highly porous and contains low molecular weight organic molecules known as the mobile phase 11 that can be extracted by organic solvents. 12,13 To explain and predict product compositions generated during pyrolysis, different coal network models have been developed.…”

Section: Coal Chemical Structure and Its Devolatilisation Modelsmentioning

confidence: 99%

Linking Thermoplastic Development and Swelling with Molecular Weight Changes of a Coking Coal and Its Pyrolysis Products

et al. 2016

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The thermoplastic development of an Australian coking coal was investigated by linking thermal swelling with changes in molecular weight of its pyrolysis products. Coal thermal swelling was investigated together with volatiles evolution and characterisation of generated volatiles (including volatile tar and light gases). The molecular weight distributions of coal and its solvent extracts were measured by using Laser Desorption/Ionization Time of Flight Mass Spectroscopy (LDI-TOF-MS). Solvent extraction (by acetone and tetrahydrofuran (THF)) was initially used on the raw coal to aid interpretation of thermoswelling by volumetric expansion measurements. The removal of ~2% solvent soluble matter from the raw coal (the mobile phase) reduced its swelling extent during heating by up to 22% (from 86% down to 68% and 64% for acetone-and THF-residues, respectively). Volatile release after solvent treatment remained unaffected. This suggested that the majority of the coal's swelling behaviour could be attributed to the formation of heat-generated liquid matter (the metaplast) during pyrolysis. Broad molecular weight changes were found in the solvent extractable component (metaplastic material extracted by acetone and THF) of the semi-coke. Prior to softening (350C), the extractable components were composed of molecules mainly <500 Da. The upper limit in molecular weight distribution of solvent extracts increased significantly to 1800 Da at the onset of swelling (400-450°C) and decreased back to ~500 Da at the end of swelling (500°C). The spectra showed that the volatile tar and acetone extract (the light solvent extract) consisted of similar repeating structures separated 12-14 Da apart. As the treatment temperature increased, the molecular weight distribution of volatile tar increased in molecular mass approaching that of the acetone extract distribution (~600 Da). THF extract molecular weight distribution was a mixture of 12-14 Da and 24 Da repeating units which only became apparent at molecular weight above 600 Da. The LDI-TOF-MS analysis of the solid coal showed that it contained a distribution of molecular structures centred at 2000 Da and spanning between 500 and 7000 Da. This raw coal spectrum also contained multiple repeating mass lines every 24 Da apart. Overall, these results suggested that the coal consisted of complicated structures which subsequently degraded into smaller fragments capable of forming a complex intermediate liquid phase and a distribution of lighter volatile tar species.

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“…During combustion under fluid conditions, the presence of the specific stages and their duration are different due to larger coal particles and considerably lower furnace temperature 1100-1170 K, but the listed combustion stages still may be taken into consideration. Some papers show that a high heating rate and small particles may result in heterogeneous particle ignition or simultaneous ignition of volatile matter and a solid (Jüntgen, 1987). Pershing and Wendt (1979) studies reveal that under typical pulverised coal combustion conditions, about a half of coal nitrogen undergoes pyrolysis.…”

Section: Nitrogen Conversion During Coal Combustionmentioning

confidence: 99%

Fuel-N Conversion to NO, N2O and N2 During Coal Combustion

Gil¹

2012

Fossil Fuel and the Environment

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Coal Characterization in Relation to Coal Combustion

Cited by 9 publications

References 23 publications

Influence of Experimental Conditions on Product Distribution During Pyrolysis of Tuncbilek Lignite (Turkey) at Low Heating Rates

Influence of Experimental Conditions on Product Distribution During Pyrolysis of Tuncbilek Lignite (Turkey) at Low Heating Rates

Linking Thermoplastic Development and Swelling with Molecular Weight Changes of a Coking Coal and Its Pyrolysis Products

Fuel-N Conversion to NO, N2O and N2 During Coal Combustion

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