Kentucky Bituminous Coal Research Articles

Investigation of an iron-based additive on coal pyrolysis and char oxidation at high heating rates

Iron-based catalysts have been shown to enhance coal pyrolysis and char oxidation at low to moderate temperatures and heating rates (< 1250 K and 1–1000 K/s). Such catalytic activity has not been demonstrated at high heating rates and temperatures approaching pulverized coal combustion applications. The effect of an iron-based additive on coal pyrolysis and char combustion was studied in a flat-flame burner system at high particle heating rates using a Kentucky bituminous coal. Pyrolysis and char reactivity of two treated coals with different catalyst loadings were studied and compared with the untreated coal. The total volatiles yield for the treated coals increased between 14 and 18% (absolute) on a dry ash-free basis compared to the untreated coal in experiments conducted at 1300 K. A first-order char oxidation model was used to compare the apparent char reactivities of the treated and untreated coals measured at 1500 and 1700 K. An increase in apparent char reactivity was observed for both treated samples.

Differential Pulmonary Inflammation and In Vitro Cytotoxicity of Size-Fractionated Fly Ash Particles from Pulverized Coal Combustion

Exposure to airborne particulate matter (PM) has been associated with adverse health effects in humans. Pulmonary inflammatory responses were examined in CD1 mice after intratracheal instillation of 25 or 100 μg of ultrafine (<0.2 μm), fine (<2.5 μm), and coarse (>2.5 μm) coal fly ash from a combusted Montana subbituminous coal, and of fine and coarse fractions from a combusted western Kentucky bituminous coal. After 18 hr, the lungs were lavaged and the bronchoalveolar fluid was assessed for cellular influx, biochemical markers, and pro-inflammatory cytokines. The responses were compared with saline and endotoxin as negative and positive controls, respectively. On an equal mass basis, the ultrafine particles from combusted Montana coal induced a higher degree of neutrophil inflammation and cytokine levels than did the fine or coarse PM. The western Kentucky fine PM caused a moderate degree of inflammation and protein levels in bronchoalveolar fluid that were higher than the Montana fine PM. Coarse PM did not produce any significant effects. In vitro experiments with rat alveolar macrophages showed that of the particles tested, only the Montana ultrafine displayed significant cytotoxicity. It is concluded that fly ash toxicity is inversely related with particle size and is associated with increased sulfur and trace element content.

Evolution of hydrogen sulfide in a fluidized bed coal gasification reactor

The rates of evolution of hydrogen sulfide have been measured for the steam/oxygen gasification of a devolatilized Western Kentucky bituminous coal, a New Mexico subbituminous coal, and a Texas lignite in a pilot-scale fluidized bed reactor, and a phenomenological model has been formulated to correlate the results. The model assumes instantaneous devolatilization and partial combustion of the coal followed by rate-limited gasification of the char in a single well-mixed stage and includes kinetic correlations for the water gas shift reaction and char hydrodesulfurization. Estimated char reactivities agree well with results obtained in other studies, and the model predictions are generally satisfactory, especially considering the relative simplicity of the model. The results indicate that sulfur present in the coal as pyrite, mercaptans, aliphatic sulfides, and disulfides is converted completely, while sulfur in aryl sulfides and thiophenes is only partially converted. A substantial fraction of the sulfur converted during gasification is released in pyrolysis - 50-70% for the subbituminous coal and 35-45% for the lignite.

Microcharacterization of micron/submicron fly ash from a pulverized‐dry‐coal‐burning power plant

AbstractMicron/submicron fly ash particles from a pulverized‐dry‐coal‐burning power plant using an Eastern Kentucky bituminous coal, EKC no. 3, were subjected to physiocochemical microcharacterization analyses. These particles, when exposed to the beam of a transmission electron microscope, had their outer layers removed and as a result the appearance of their inclusions changed. Microchemical analysis by Auger electron spectroscopy (AES) revealed that splashed‐away layers were rich in sulfur and carbon with some coal‐originated, volatilized, condensed matter. The AES was used to analyze the composition of these layers and provide a thickness profile of the coating materials. Scanning electron micrographs revealed that the particles were partially hollow spheroids.

Modeling a pilot-scale fluidized bed coal gasification reactor

A steady-state model has been developed to simulate the North Carolina State University pilot-scale fluidized bed coal gasification reactor. The model involves instantaneous devolatilization of coal at the top of the gasifier (freeboard region) and char combustion and gasification in the fluidized bed. A two-phase (emulsion-dilute gas) representation of the fluidized bed incorporates the phenomena of jetting, bubbling, slugging, and mass and heat transfer between phases, and enables the prediction of individual species flow rates and temperature profiles within the bed. The model has been successfully used to simulate the gasification of a devolatilized Western Kentucky bituminous coal and a New Mexico subbituminous coal and to predict effects of various operating parameters on key gasifier performance variables.

Coal pyrolysis kinetics by non-isothermal thermogravimetry

The thermal degradation of a West Kentucky bituminous coal and its demineralized maceral content has been studied by rapid heating rate non-isothermal thermogravimetry. The digitally recorded data has been analyzed by a FORTRAN computer program, which enables a regional kinetic treatment of the entire data set. The initial stage of the pyrolysis conforms to a diffusional rate-controlling step. The major weight loss region conforms to a model of a set of first-order degradation reactions. The overall kinetic parameters for this region are best calculated by means of the Kissinger or Friedman procedures, rather than the Arrhenius method, which can yield spurious results. The final stage of the pyrolysis is not completely amenable to kinetic analysis; the resulting kinetic parameters yield a less than exact curve fit of experimental data. In general, however, over the entire range of the decomposition, the curve-fit is comparable to that obtained by the use of the more complex, statistically distributed, empirical kinetic equation approach.

Coal liquefaction catalysis by industrial metallic wastes

Catalytic activity of industrial metallic wastes in coal liquefaction was examined in a 100lb/day continuous coal processing development unit. Red mud, a waste material from the aluminium industry, and an electric furnace flue dust containing Ni, Mo, Co and Fe showed a pronounced effect on the conversion of a Kentucky bituminous coal. Coal conversion and oil production increased significantly with the addition of red mud and flue dust. Comparison of the catalytic activity of pyrite, red mud, and flue dust, based on selectivity analysis, showed that red mud was the most desirable disposable catalyst. However, if the primary goal of coal liquefaction is high oil production, irrespective of hydrogen consumption, pyrite is the most active catalyst among those discussed in the paper.

Enthalpy measurements on distillates produced from a Utah coal by the Char-Oil-Energy-Development process and from a Kentucky bituminous coal by the Synthoil process

Enthalpy data for a light distillate of a coal-derived liquid produced from a Utah coal by the Char-Oil-Energy-Development (COED) process are presented at pressures of 415, 690, 3450, 6895, and 10340 kPa (60, 100, 500, 1000, 1500 psia) for temperatures between 18.3 and 383/sup 0/C (65 to 721/sup 0/F). Results for a distillate of a syncrude produced from a Kentucky bituminous coal by the Synthoil process are also presented at pressures of 1035, 1380, 3450, 6895, and 10340 kPa (150, 200, 500, 1000, 1500 psia) at temperatures between 18.3 and 395/sup 0/C (65 and 742/sup 0/F). The data were obtained in a boil-off calorimeter with Freon-11 (CFC1/sub 3/) as a reference-fluid.

Fate of solvents in the non-catalytic depolymerization of Kentucky bituminous coal

To study the fate of the solvents in the non-catalytic liquefaction of Kentucky bituminous coal, a number of batch liquefaction experiments have been carried out using hydrophenanthrenes and coal-derived hydrogenated recycle solvents. Filtrates from the first runs have been rehydrogenated and used as solvents for additional liquefaction experiments. The reactions have been followed by detailed analysis of the feeds and products. At constant temperature and reaction time, the conversion levels are affected by the amount of transferable hydrogen, H s (up to a value of about 0.6 wt.% of the feed), by the coal concentration and, to a lesser extent, by the pressurizing gas. The solvents are depleted by isomerization, cracking, and adduction-polymerization reactions. Only about 50% of the initial solvent is available for use in the second-pass runs. In addition, the quality of the second-pass solvents is lower than that of the initial solvents due to a decrease of 6-membered hydroaromatic rings and an increase of 5-membered hydroaromatic rings which are poor hydrogen donors.

Dependence of coal liquefaction behaviour on coal characteristics. 2. Role of petrographic composition

The techniques used were the same as those used in Part 1 (p 34). Comparison of the liquefaction behaviour of two lithotypes from a Kentucky bituminous coal indicated that in this process pseudovitrinite is a reactive maceral. The hydrogenation of sets of maceral concentrates obtained from a New Mexico sub-bituminous and a Kentucky bituminous coal showed fair correlations between conversion and the total concentration of the presumed reactive macerals (vitrinite, pseudovitrinite and sporinite). Similar concentrates from a Montana lignite showed no such correlation; the one sample that showed a high conversion was a high-density fraction that had a high mineral-matter content and in which nearly all the pyrite in the coal had accumulated. Two samples that have boghead and cannel characteristics gave quite different results on hydrogenation. Both were highly aliphatic in structure and had unusually high hydrogen contents and volatile matter. One, which contained appreciable proportions of sporinite, alginite and resinite, gave essentially no conversion to oil. The other, predominantly vitrinitic but containing alginite as the second most abundant maceral, gave an excellent yield of an oil of low viscosity and aromaticity. It was concluded that although rank, petrographic composition and perhaps geological history are important factors determining liquefaction behaviour, there are other characteristics of coals that may at times override these basic parameters, and the composition of the inorganic matter may be the most significant of these other characteristics.

Manufacture of gas

The techniques used were the same as those used in Part 1 (p 34). Comparison of the liquefaction behaviour of two lithotypes from a Kentucky bituminous coal indicated that in this process pseudovitrinite is a reactive maceral. The hydrogenation of sets of maceral concentrates obtained from a New Mexico sub-bituminous and a Kentucky bituminous coal showed fair correlations between conversion and the total concentration of the presumed reactive macerals (vitrinite, pseudovitrinite and sporinite). Similar concentrates from a Montana lignite showed no such correlation; the one sample that showed a high conversion was a high-density fraction that had a high mineral-matter content and in which nearly all the pyrite in the coal had accumulated. Two samples that have boghead and cannel characteristics gave quite different results on hydrogenation. Both were highly aliphatic in structure and had unusually high hydrogen contents and volatile matter. One, which contained appreciable proportions of sporinite, alginite and resinite, gave essentially no conversion to oil. The other, predominantly vitrinitic but containing alginite as the second most abundant maceral, gave an excellent yield of an oil of low viscosity and aromaticity. It was concluded that although rank, petrographic composition and perhaps geological history are important factors determining liquefaction behaviour, there are other characteristics of coals that may at times override these basic parameters, and the composition of the inorganic matter may be the most significant of these other characteristics.