Some aspects of changes in the macromolecular structure of coals in relation to thermoplastic properties

Butterfield, I. M.; Thomas, K. Mark

doi:10.1016/0016-2361(95)80008-6

Cited by 28 publications

(17 citation statements)

References 14 publications

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“…With further heating up to 1000-1200°C, this intermediate carbon material is converted into a high-temperature coke with a strong mechanical resistance and moderate reactivity towards CO 2 . The development of fluidity up to 500°C is considered a key step in coal thermochemical behavior in a coke oven and, consequently, for the structure and properties of the resultant coke (Patrick, 1975;Loison et al, 1989;Marsh, 1992;Butterfield and Thomas, 1995;Diez, in press). In fact, the optical texture achieved in the semicoke stage is generally retained in the coke (Patrick et al, 1973(Patrick et al, , 1979Fukuyama et al, 1981;Rouzaud, 1993, 1994).…”

Section: Introductionmentioning

confidence: 98%

Influence of charcoal fines on the thermoplastic properties of coking coals and the optical properties of the semicoke

Guerrero

Díez

Borrego

2015

International Journal of Coal Geology

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The aim of this work is to investigate the influence of the addition of organic inerts such as charcoal with a wellcontrolled particle size on the development of fluidity in three coking coals of different rank, maceral composition, and rheological properties. Three size fractions of charcoal, b20, 20-80, and 80-212 μm, that can be considered as artificially prepared inertinites were used. The different charcoal fractions were added in amounts of 2, 5, 10, and 15 wt.% to selected high-quality coking coals with a Gieseler maximum fluidity (Fmax) of 373 (LF), 541 (MF), and 1891 (HF) ddpm. Increasing the amount of charcoal in the blend led to a progressive inverse exponential reduction in fluidity. This reduction was accompanied by a shortening of the fluid interval due to an increase in the softening temperature. In the case of the finest charcoal fraction, the inhibition of fluidity was even more pronounced. The HF coal with a relatively high fluidity was very sensitive to minimum amounts of charcoal addition, losing nearly half of its fluidity when 5 wt.% charcoal was added. A similar reduction in Fmax was also observed for LF, while MF with only a slightly higher fluidity displayed a different trend. From the results it can be seen that the inherent characteristics of a coal are critical factors that affect the extent of the reduction in fluidity caused by the incorporation of charcoal. The differences can be partially attributed to the amount of inertinite present in the parent coal and to the macerals within the inertinite, especially fusinite, semifusinite, and inertodetrinite. In relation to petrographic changes in the matrix of the semicokes, there is a general trend for isotropic material to increase and the size of the anisotropic textures to decrease with the addition of charcoal. Inclusions within the semicoke matrix also change according to the amount and the size of the charcoal added to coal.

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Section: Introductionmentioning

confidence: 98%

Influence of charcoal fines on the thermoplastic properties of coking coals and the optical properties of the semicoke

Guerrero

Díez

Borrego

2015

International Journal of Coal Geology

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“…The thermoplastic behavior of coal particles during carbonization has thus been studied extensively with several types of analysis techniques and different kinds of coals. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Some researchers exhibit that coal thermoplasticity depends strongly on the amounts of chloroform solubles naturally-present in coal, 1,4,6) low-molecular-weight compounds (metaplasts) 2,3) and/or transferable hydrogen 7,10) formed upon carbonization. It has also been reported that the sulfur and nitrogen present in coal, denoted as coal-S and coal-N, respectively, affect coal fluidity, [17][18][19][20] and that the addition of denzo-[c]-acridine (C17H11N) to a coal blend, even at a small amount of 3 mass%, enhances the tensile strength of the coke after carbonization by a factor of about 1.2.…”

Section: Introductionmentioning

confidence: 99%

Sulfur and Nitrogen Distributions during Coal Carbonization and the Influences of These Elements on Coal Fluidity and Coke Strength

et al. 2014

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The present study focuses on examining the fate of coal-S and coal-N during carbonization in detail and making clear the effects of these elements on coal fluidity and coke strength. When eight kinds of caking coals with 80-88 mass%-daf C are carbonized in high-purity He at 3°C/min up to 1 000°C with a quartzmade fixed bed reactor, 50-75% of coal-S remains as FeS and organic-S in the coke, and the rest is released as tar-S and H2S. Most of coal-N is also retained in the coke, and the remainder is converted to tar-N, HCN, NH3 and N2. The eight coals give Gieseler maximum fluidity values between 435 and 480°C, and the value tends to be larger at a smaller sulfur content in coal or in the carbonaceous material recovered after carbonization at 450°C. It also seems that the value increases with increasing nitrogen content in coal or total amount of either HCN or NH3 formed up to 450°C. Furthermore, the addition of S-containing compounds to an Australian bituminous coal lowers coal fluidity and coke strength considerably, whereas indole gives the reverse effect on them. On the basis of these results, it is suggested that coal-S or some coal-N has a negative or positive effect on the two properties, respectively.

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“…With increasing rank, these types of bonds are replaced by H bonds, which are weaker and so the coals start to fuse on heating. In the case of higher rank coals, the aromaticity increases along with the macromolecular size and covalent cross-linkages which in turn lead to a decrease in fluidity [23][24][25]. This property is essential for the development of the structure and properties of cokes and for this reason the influence of briquettes on this coal property has been the subject of study in the present work.…”

Section: Variation Of the Thermoplastic Properties Of The Coal Due Tomentioning

confidence: 99%

Partial briquetting vs direct addition of biomass in coking blends

Montiano

Díaz-Faes

Barriocanal

2014

Fuel

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In this work partial briquetting is employed as a means of biomass densification to allow for biomass inclusion in coking coal blends. The effect of increasing the bulk density was evaluated by comparison with direct addition. Two briquettes of different composition were studied. The influence of the briquettes on the Gieseler plasticity of the coals was determined. It was found that the effect of the binder was not enough to compensate for the decrease in plasticity produced by the inert components of the briquettes. Carbonizations were carried out in a movable wall oven of 17 kg capacity and the quality of the cokes produced was tested by evaluating their mechanical strength, coke reactivity to CO 2 and post-reaction strength. In addition, the porosity and ash chemistry of the cokes was determined and an attempt was made to establish a relation between these results and the quality of the cokes. Coke quality results suggest that 10-15 wt% of briquettes containing biomass can be included in coking blends.

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Some aspects of changes in the macromolecular structure of coals in relation to thermoplastic properties

Cited by 28 publications

References 14 publications

Influence of charcoal fines on the thermoplastic properties of coking coals and the optical properties of the semicoke

Influence of charcoal fines on the thermoplastic properties of coking coals and the optical properties of the semicoke

Sulfur and Nitrogen Distributions during Coal Carbonization and the Influences of These Elements on Coal Fluidity and Coke Strength

Partial briquetting vs direct addition of biomass in coking blends

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