Fuel Processing Technology (v.86, #1)

Prediction of coke quality at Baosteel by Qun Zhang; Xinci Wu; Anzhu Feng; Meiren Shi (1-11).
On the basis of the correlation between the properties of 19 coals and 64 coal blends and their cokes carbonized in a simulated coke oven (SCO), a coke quality prediction method has been developed and successfully tested for many Chinese coals that have been used for coke-making at Baosteel. The coke quality prediction is aided by the fact that V d, A d,S td, G, lg MF is additive, and the mineral composition of coal (represented by mineral catalysis index (MCI)) is one of another key factors affecting coke quality besides the coal rank and the plastic properties of coal. The prediction method could be used for new coal evaluation, blend design and cost control.
Keywords: Coke quality; Coal property; Prediction;

Isolation of prime value products from crude xylenol fraction of noncaking coal-derived tar acids by Kaushal K. Tiwari; Somnath Banerjee; Bani P. Das; Kumaresh C. Bit; Umesh C. Dumka (13-21).
An efficient method for the separation of prime value products from crude xylenol fraction of noncaking coal-derived tar acids involving suitable distillation technique is described. The feed as well as the products was analysed by gas chromatography (G.C.). The crude xylenol comprising a number of close-boiling phenolic compounds was fractionated under reduced pressure to yield three cuts, viz. cresols (30.7%), xylenols (31.2%) and dihydric phenols (23.3%). The dihydric phenols fraction termed as high boiling tar acids (HBTA) was found to contain significant amounts of catechol (6.4%), methyl catechols (32.3%), resorcinol (12.7%) and methyl resorcinols (8.6%). Catechol together with its homologues and resorcinol with its homologues were isolated from the HBTA. These products, not available from the HBTA of metallurgical coke plants, have been shown to offer distinct marketing advantages. A conceptual scheme for the treatment of crude xylenol as well as application pattern of various products obtainable from the crude mixture is presented.
Keywords: Carbonisation products; Crude xylenols; Dihydric phenols; Distillation; Tar acid;

Trace elements (Mn, Cr, Pb, Se, Zn, Cd and Hg) in emissions from a pulverized coal boiler by Yaji Huang; Baosheng Jin; Zhaoping Zhong; Rui Xiao; Zhiyong Tang; Huifeng Ren (23-32).
The concentrations of seven trace elements (Mn, Cr, Pb, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured quantitatively in a 220 tons/h pulverized coal boiler. Factors affecting distribution of trace elements were investigated, including fly ash diameter, furnace temperature, oxygen concentration and trace elements' characteristics. Modified enrichment factors show more directly element enrichment in combustion products. The studied elements may be classified into three groups according to their emission features: Group 1: Hg, which is very volatile. Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be located between groups 1 and 2. Cr has properties of both Groups 1 and 3. The smaller the diameter of fly ash, the higher is the relative enrichment of trace elements (except Mn). Fly ash shows different adsorption mechanisms of trace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of trace elements (except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen concentration will not always improve the volatilization of trace elements. Pb forms chloride more easily than Cd during coal combustion.
Keywords: Trace element; Occurrence; Volatility; Relative enrichment; Classification of elements; Coal ash;

Reduction of iron oxide in carbon monoxide atmosphere—reaction controlled kinetics by K. Mondal; H. Lorethova; E. Hippo; T. Wiltowski; S.B. Lalvani (33-47).
Thermogravimetric analysis (TGA) of the reduction of Fe2O3 in a continuous stream of 100% CO was conducted at temperatures ranging from 800 to 900 °C. X-ray diffraction analysis of solids identified the presence of iron, graphite and a carbide of iron as the products of reactions. A kinetic model based on the first-order irreversible rate kinetics was developed and fitted to the TGA data so as to estimate the rate constants for each reduction reaction. The reaction pathways considered in this analysis involved reduction of iron oxides, Boudouard reaction and iron-carbide formation. The rate parameters were calculated and compared with data reported in literature.
Keywords: Iron oxide; Carbon monoxide; Reduction; Kinetics;

Enzymatic oxidation of dibenzothiophene (DBT) catalyzed by laccase in the presence of 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) was compared with the chemical oxidation with hydrogen peroxide catalyzed by phosphotungstic acid. Enzymatic oxidation with laccase (2.4 U/ml) of 25 μM DBT with 1.5 mM ABTS required a molar ratio [O2]/[ABTS]=140 and 72 h at 40 °C in a water–acetonitrile reaction mixture, showing a rate constant of k 1=−6.3×10−4 min−1. Whereas peroxide oxidation of 10 mM DBT with 39 μM phosphotungstic acid required only a molar ratio [H2O2]/[DBT]=2, showing a rate constant of k 2=−6.1×10−2 min−1 in a hexane–ethanol system. A sample of diesel fuel, containing 342 ppm of sulfur, was chemically oxidized by an excess of hydrogen peroxide and 119 μM phosphotungstic acid dissolved in ethanol, in less than 3 h at 60 °C and atmospheric pressure. No sulfur could be detected in these samples after an additional extraction with an equal volume of ethanol.
Keywords: Laccase; Dibenzothiophene; Phosphotungstic acid; Deep desulfurization; Diesel;

Effect of extraction condition on “HyperCoal” production (2)—effect of polar solvents under hot filtration by Takahiro Yoshida; Chunqi Li; Toshimasa Takanohashi; Akimitsu Matsumura; Shinya Sato; Ikuo Saito (61-72).
In order to produce ashless coal (HyperCoal) in a high-yield, thermal extraction with several organic solvents under hot filtration at 360 °C using a flow-type extractor was performed, and the effect of the extraction solvent on the extraction yield and ash content in the HyperCoal was investigated. Crude methylnaphthalene oil (CMNO), a cost-effective industrial solvent, gives much higher extraction yield (∼80%) than light cycle oil (LCO), which was previously reported as a useful solvent for HyperCoal production. The high extraction yield can be obtained due to the solvent-induced relaxation of coal aggregates by the nitrogen-containing compounds, in addition to the thermal-induced relaxation of them. Gas chromatography/mass spectrometry (GC/MS) analysis of the solvent showed that the polar compounds contained mainly consisted of quinoline-type ones. The effect of addition of some polar compounds into non-polar extraction solvent on the extraction yield was investigated. The addition led to an increase in the extraction yield, while, the quantities of solvent remained in the extract and residue also increased. The extraction yield did not reach the same level as the industrial solvents used here, even when the nitrogen content in the mixture of solvent/additives was almost identical to that in those solvents.
Keywords: Ashless coal; HyperCoal; Extraction yield; Additive; Polar compound;

New bimodal pore catalysts for Fischer–Tropsch synthesis by Misao Shinoda; Yi Zhang; Yoshiharu Yoneyama; Kiyoshi Hasegawa; Noritatsu Tsubaki (73-85).
A simple preparation method of bimodal pore supports was developed by introducing SiO2 or ZrO2 sols into large pores of SiO2 gel pellets directly. The pores of the obtained bimodal pore supports distributed distinctly as two kinds of main pores. On the other hand, the increased BET surface area and decreased pore volume, compared to those of original silica gel, indicated that the obtained bimodal pore supports formed according to the designed route. The obtained bimodal pore supports were applied in liquid-phase Fischer–Tropsch synthesis (FTS) where cobalt was supported. The bimodal pore catalysts presented the best reaction performance in liquid-phase Fischer–Tropsch synthesis (FTS) as higher reaction rate and lower methane selectivities, because the spatial promotional effect of bimodal pore structure and chemical effect of the porous zirconia behaved inside the large pores of original silica gel.
Keywords: Bimodal pore support; Fischer–Tropsch synthesis (FTS); Syngas; Cobalt catalyst; Zirconia;

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