Addition Effect of Model Compounds of Coal Extract on Coke Strength

Koyano, Koji; Ueoka, Kenta; Takanohashi, Toshimasa; Fukada, Kiyoshi; Ota, Kohei

doi:10.2355/isijinternational.51.1044

Cited by 12 publications

(8 citation statements)

References 9 publications

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“…To overcome the problem of decrease in coke strength, there has been recent interest in using oil/coal derived additives as binders so that the coke strength is maintained even with increased low quality non-caking coals addition. [3][4][5][6] Takanohashi et al explained this increase in coke strength by investigating the interaction between caking and slightly caking or non-caking coals using NMR analysis and H/C ratio and concluded that binders (HPC) enhance the thermoplasticity of the coal blend due to their high thermoplasticity and overlapping thermoplastic temperature range with that of base coals. 4) Sakimoto et al introduced carbon matrix connectivity index to estimate the coke drum index which directly correlates with the coke strength.…”

Section: Introductionmentioning

confidence: 99%

Physical and Chemical Characteristics of Coal-binder Interface and Carbon Microstructure near Interface

et al. 2014

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In this study, investigations were made to understand the mechanism of increase in coke strength on binder addition by analyzing physical and chemical characteristics of coal-binder interface. Three binders, oil derived Asphalt pitch (ASP), coal derived HyperCoal (HPC) and Coal tar pitch (CTP) were used to understand the effect of binder. A new method to observe the coal-binder interface boundary at microscopic level by Scanning Electron Microscope (SEM) was developed. When base coal was a non-caking coal, coal-binder interface boundary was clearly observed by SEM for the first time. From observed images, it was found that ASP and HPC bound differently on the coal surface. When base coal is a caking coal, the interface could not be distinguished but sulfur mapping confirmed the presence of interface. Preliminary Laser Raman analysis suggests there may be some interactive effect of coal and binder on each other's carbon structure development. Contribution of fraction of coal surface coated with binder towards coke strength is considered.

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Section: Introductionmentioning

confidence: 99%

Physical and Chemical Characteristics of Coal-binder Interface and Carbon Microstructure near Interface

et al. 2014

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“…The soluble fraction contained THF, 1-MN solvent and 1-MN soluble coal fraction. 3,6,9,19,20,[25][26][27]32) As can be seen from the Fig. 1, in the case of THF wash approach, 1-MN soluble coal fraction and insoluble fraction are separated.…”

Section: Methodsmentioning

confidence: 89%

“…Another approach is to chemical upgrade the coal by increasing its H/C ratio by solvent treatment. [3][4][5][6][7][8][9][10][11][20][21][22][23][24][25] Takanohashi et al treated different coals with 1-MN and obtained 1-MN soluble fractions. 7,32) This 1-MN soluble coal fraction was called coal-derived binder.…”

Section: Introductionmentioning

confidence: 99%

“…They reported that adding 5-10% of binder increases the strength of the cokes. 3,5,[6][7][8][9]27,29,31) They investigated the interactions between caking and slightly caking or non-caking coals using NMR analysis and H/C ratio and concluded that the binders (HPC) enhance the thermo-plasticity of the coal blend due to their high thermo-plasticity and overlapping thermoplastic temperature range with that of coals. 3,[19][20][21][23][24][25][26][27] Sakimoto et al introduced carbon matrix connectivity index to estimate the coke drum index which directly correlates with the coke strength.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Carbonization Heating Rate on the Tensile Strength of Cokes Prepared from Chemically Upgraded Low Rank Coals

et al. 2019

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In this study, effect of carbonization heating rate and solvent removal method on the tensile strength of cokes prepared from chemical upgraded coal samples was investigated. A low rank coal, L coal, was solvent treated at 420°C, 2 h with 1-methylnapthlene (1-MN) solvent. Upgraded coal samples were obtained by removing 1-MN from the solvent treated samples. Two different approaches were applied to remove 1-MN from the treated samples; washing with tetrahydrofuran (THF) and that with n-hexane (HEX). All upgraded samples were first pelletized under a mechanical pressure and time of 40 MPa and 10 min, respectively, and then carbonized at heating rate of 3, 10 or 25°C/min. Carbonized coke samples strength was measured as tensile strength (MPa). It was found that lower heating rate gave higher tensile strength irrespective of solvent removal method. This may be due to that lower heating rates allowed the coal upon heating to undergo softening, melting and re-solidification for longer time. n-HEX-washed upgraded samples showed higher strength than THF-washed ones when the same heating rates were applied. Surfaces of coke samples were observed by scanning electron microscopy (SEM) and it was found that pore development structures of cokes n-HEX-washed samples and those from THF-washed samples were different from each other. This difference may be responsible for that in the strength.

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“…[9][10][11] Koyano et al investigated the effect of the aromatic ring size of model compounds added to coals on the coke strength of blended coals, and reported that the coke strength was increased by adding more than 4 aromatic rings and the effect was enhanced with increase in the number of aromatic rings. 12) Sakimoto et al also reported that the aromatic ring size of HPCs obtained from the extraction of low-rank coals with 1-methyl naphthalene at 673 K was around 3, although the extraction yield was 20-26 mass%, daf. 9) In the present study, in order to utilize low-rank coals efficiently, polar solvents were used as an extraction solvent, because a higher extraction yield can be expected.…”

Section: Introductionmentioning

confidence: 99%

Reforming of Low-rank Coal by Chemical Upgrading

et al. 2019

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A subbituminous coal was treated with a wash oil or 1-methyl naphthalene (MN), for 1 hr or 2 hr at 673 K or 693 K under nitrogen, in order to chemically upgrade the low-rank coal. In case of wash oil as the treated solvent, the extraction yield at 673 K reached 66 mass%, daf after recovering the solvent, however, some of wash oil remained in the extract because the wash oil contained polar compounds of 8.5 masst%. The extraction yield with MN at 673 K was 41.2 mass%, daf and it decreased with an increase in the severity of the extraction condition; it was 36.3 mass%, daf at 693 K for 2 hr. The more polar solvent which contained polar compounds of 21.7 mass%, called the Super-Solvent (SS), was successfully produced by separation of the wash oil with methanol/water (3:1 by weight) mixture. The extract obtained from the extraction with SS showed similar degree of the H/C and O/C atomic ratios as bituminous coals, indicating that chemically upgrading reactions might occurred by the solvent treatment. After the solvent treatment with MN at 693 K for 2 hr, hexane was used as the washing solvent, resulting that the ratio of hexane soluble fraction was a few. Thus, the solvent upgraded coal originated from a low-rank coal was successfully produced in high yield. The H/C and O/C ratios of the solvent upgraded coal became the similar level as those of caking coals. Decarboxylation and aromatization reactions might occur during the solvent treatment.

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Addition Effect of Model Compounds of Coal Extract on Coke Strength

Cited by 12 publications

References 9 publications

Physical and Chemical Characteristics of Coal-binder Interface and Carbon Microstructure near Interface

Physical and Chemical Characteristics of Coal-binder Interface and Carbon Microstructure near Interface

Effect of Carbonization Heating Rate on the Tensile Strength of Cokes Prepared from Chemically Upgraded Low Rank Coals

Reforming of Low-rank Coal by Chemical Upgrading

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