Showing papers on "Coal published in 1989"
TL;DR: In this paper, the authors reviewed literature data for the rate of gasification of coal chars with oxygen, CO2 and steam and clarified the factors controlling this process. But, they did not consider the effect of the number of active sites in the coal matrix.
319 citations
TL;DR: In this paper, the authors assess the technology and economics of hydrogen production by conventional and advanced processes and conclude that steam reforming of methane is the most economic near-term process among the conventional processes.
311 citations
TL;DR: In this paper, a comprehensive review and analysis of hydrogen in efficient passenger vehicles is presented, focusing on hydrogen production and distribution, on-board storage technology, refuelling, vehicle performance and safety, environmental impacts of hydrogen use, and life-cycle costs.
203 citations
TL;DR: Peat has been studied in several geologic settings: (1) glaciated terrain in cold temperate Maine and Minnesota, U.S.A., (2) an island in the Atlantic Ocean off the coast of Maine, where sea level is rising; (3) the warm temperate United States Atlantic and Gulf Coastal Plains, and (4) the tropical coast of Sarawak, Malaysia, and the tropical delta of the Batang Hari River, Sumatra, Indonesia.
153 citations
TL;DR: In this article, the influence of char fragmentation on the size distribution of combustion-generated ash has been investigated in a detailed laboratory study utilizing both coals and synthetic chars, and it was found that the macroporosity of the char was the important variable in determining fragmentation behavior, as evidenced by results obtained from combustion of synthetic chars.
132 citations
TL;DR: In this paper, the magnitude of the contact angle on vitrinite is shown to be a function of coal rank, increasing with increasing rank to a maximum for low volatile bituminous rank coals then decreasing for anthracite.
127 citations
TL;DR: In this paper, a quantitative model of softening coal pryolysis is developed and tested against observed behavior. The model quantitatively describes the transient softening behavior including the initiation, duration, and magnitude of plasticity and swelling of the particle.
Abstract: A quantitative model of softening coal pryolysis is developed and tested against observed behavior. The model treats intraparticle transport of gases and metaplast throughout the softening stage of pyrolysis via growth of bubbles uniformly dispersed in the molten coal. The model quantitatively describes the transient softening behavior including the initiation, duration, and magnitude of plasticity and swelling of the particle. The model kinetic parameters are derived from experiments, in which a highly softening Pittsburgh No. 8 bituminous coal was pyrolyzed, and total weight loss, and yields and molecular weight distributions of tars and pyridine extractables of cooled chars were measured. Model predictions of effects of pressure, particle diameter and temperature on tar yields and weight losses, of effects of pressure on swelling ratio, and of effects of heating rate on plasticity are presented. The model provides good fits to the laboratory data and predicts trends in pyrolysis behavior in good qualitative accord with expectations based on published data.
126 citations
TL;DR: In this paper, the authors measured the low-temperature (25-140°C) oxidation rate of a single coal sample in a well-insulated vessel, while at the same time performing gas analyses.
125 citations
TL;DR: In this article, the authors proposed a pre-combustion desulfurization of coal using biotechnology, which may provide a solution to acid rain pollution from coal combustion.
124 citations
TL;DR: In this paper, the authors investigated an unknown mechanism by which N{sub 2}O is formed in coal flames, using both detailed kinetic modeling and plug-flow simulator experiments.
121 citations
TL;DR: In this paper, the extinction coefficient of the N-H stretching ir absorption for coal-derived asphaltenes was calculated using X-ray photoelectron spectroscopy.
TL;DR: In this article, the secondary reactions of volatiles from rapid pyrolysis of Liddell coal have been studied using a two-stage reactor, and the effects of the cracking temperature and the residence time on the final product yields were investigated in an inert atmosphere between 500-900°C and 0.2-14 s.
01 Jan 1989
TL;DR: In this article, the authors studied the kinetics and the mechanism of the adsorption of sorbents to coal flue gas during coal combustion and showed that bauxite, kaolinite and emathlite are promising alkyl compounds.
Abstract: Coal usually contains sodium and potassium minerals in various chemical and physical forms. During the combustion or gasification of coal, much of this alkali is released into the gas phase. This vapor is usually in the form of alkali chlorides. In the presence of sulfur, alkali sulfates are also formed. This alkali condenses on and reacts with ash to form low melting point phases that enhance fouling. Cleaning of coal removes some of the alkali but is not effective enough to decrease the alkali concentration to acceptable levels. A promising technique for the removal of alkali from hot flue gases is by using materials (sorbents) that will adsorb and/or react with alkali vapors. In general, the sorbents can be used in two ways. One method is by passing the alkali-laden flue gas through a fixed bed of an appropriate sorbent. This process has been considered for alkali removal from flue gases in the combined-cycle power generation from coal. The second method is the injection of sorbents with coal for the in-situ capturing of alkali during pulverized coal combustion. This method has received much less attention. The choice of a suitable sorbent depends on the coal properties and the process operatingmore » conditions. In general, however, the important characteristics desired in a potential sorbent are high temperature compatibility, rapid rate of adsorption, high loading capacity, transformation of the alkali into a less corrosive form and irreversible adsorption to prevent the release of adsorbed alkali during process fluctuations. Previous studies in this laboratory and those of other investigators have suggested that bauxite, kaolinite and emathlite are promising alkali vapor sorbents. The purpose of this study is to obtain fundamental information on the kinetics and the mechanism of alkali adsorption on these sorbents.« less
TL;DR: In this article, the feasibility of this process has been evaluated in a pilot scale test furnace and by the use or a boiler performance model to assess the impact on the performance of a 50MWe lignite fired boiler using oxygen plus recycled products as the oxidant.
Abstract: The combustion of coal in oxygen with recycled flue gases has been proposed as a means of recovering carbon dioxide during power generation in existing boilers. The feasibility of this process has been evaluated in a pilot scale test furnace and by the use or a boiler performance model to assess the impact on the performance of a 50MWe lignite fired boiler using oxygen plus recycled products as the oxidant. Results show that flue gas recycle is a viable means of controlling combustion and heat transfer characteristics, and that recycle conditions exist at which performance changes are minimal compared to operation on air.
TL;DR: In this article, coal samples from directly above tonsteins (altered volcanic ash partings) are enriched in desmocollinite, telinite, and detrocollinite.
Journal Article•
TL;DR: In this paper, a comparison of elemental trends between the lowest bright and second bright lithotype suggest that the swamp became less acidic with time, possibly due to the influx of clays and other silicates present in the bone lithotype.
TL;DR: In this paper, a series of coals (mainly high volatile bituminous) was devolatilized at a relatively low temperature (500 °C) in a fixed-bed reactor in an inert atmosphere.
TL;DR: In this paper, time-resolved measurements of the rate of devolatilization of high volatile bituminous coal particles in nitrogen at gas temperatures of 1050 and 1250 K are presented.
TL;DR: In this article, the thermal properties of coal slags formed in the British Gas/Lurgi slagging gasifier have been measured for temperatures between 298 and 1800 K. The authors derived values of heat capacity and enthalpy using a model relating the property value to the chemical composition of the slag and these were found to be in good agreement with experimental data.
TL;DR: The biosolubilities (susceptibility to being attacked and solubilized by microbes) of 17 coals by 9 microbes were evaluated, as were solubilities of these coals in dilute alkaline buffers as mentioned in this paper.
Abstract: The biosolubilities (susceptibility to being attacked and solubilized by microbes) of 17 coals by 9 microbes were evaluated, as were solubilities of these coals in dilute alkaline buffers. A direct relationship between coal alkali- and biosolubilities was observed suggesting a common mechanism of coal solubilization. These data are consistent with the hypothesis that a mechanism by which microorganisms solubilize coal is by production of alkaline materials that raise medium pH and effect solubilization.
TL;DR: In this paper, the physical properties of coal slags relevant to the fluid flow in the British Gas/Lurgi slagging gasifier were measured for temperatures between 1400 and 1800 K. Mathematical models for the estimation of these properties on the basis of the chemical composition of the slag have been developed and compared with experimental data.
TL;DR: Coal polymers, water soluble at pH 3.5, were prepared from North Dakota lignite and German subbituminous coal in 35-61% yield as mentioned in this paper.
Abstract: Coal polymers, water soluble at pH 3.5, were prepared from North Dakota lignite and German subbituminous coal in 35–61% yield. Gel permeation chromatography showed a major component of relatively narrow molecular weight range >75,000. The material did not dialyze through a 12,000-14,000 MW cutoff membrane under several conditions. Minor amounts of smaller fragments were present, but monomeric components were not detected. Incubation of soluble polymer with lignin peroxidase ofPhanerochaete chrysosporium caused substantial disappearance of the high molecular weight polymer and formation of smaller amounts of both higher and lower molecular weight components, but not of monomeric compounds. Addition of veratryl alcohol enhanced depolymerization. Coal polymer competitively inhibited veratryl alcohol oxidation by lignin peroxidase.
TL;DR: The export of British coal was a major feature of late 19th-century ocean shipping and it has been argued that coal was key to the success of British shipping, but close examination raises doubts as discussed by the authors.
TL;DR: In this article, a two-dimensional (15 × 200 × 400 × 400 mm) high-temperature fluidized bed, devolatilization ignition and combustion phenomena of single coal particles have been studied.
TL;DR: In this paper, spherical coal particles (5 to 12 mm diameter) from three Australian bituminous coals were devolatilized in an inert atmosphere of nitrogen at 850 °C, using a specially designed thermogravimetric rig based on an electrically heated stainless steel tubular reactor.
TL;DR: In this article, the rank of coal beds in the Fruitland Formation in the central part of the San Juan basin, where major gas production occurs, increases to the northeast and ranges from highvolatile B bituminous coal to medium-volatile coal (Rm values range from 0.70 to 1.45%).
TL;DR: In this paper, the results of catalytic hydropyrolysis experiments in which greater than 60% daf coal basis yields of tar are produced with weight ratios of tar to gases up to 80% higher than observed in an uncatalyzed reaction were reported.
Abstract: In this paper the authors report the results of catalytic hydropyrolysis experiments in which greater than 60% daf coal basis yields of tar are produced with weight ratios of tar to gases up to 80% higher than observed in an uncatalyzed reaction. The work has also shown that dispersed sulfided molybdenum and hydrous titanium oxide (HTO) catalysts coated directly on the coal are superior to Lewis acids and alumina supported hydrogenation catalysts in terms of tar yields achieved and reduction of the amount of light hydrocarbon gases produced. In addition, they have performed two-stage hydropyrolysis tests which demonstrate that the tar produced is readily upgraded.
TL;DR: In this article, the authors used solid-state 13 C nuclear magnetic resonance (NMR) and pyrolysis-gas chromatography-mass spectrometry (py-gc-ms) techniques for detailed structural evaluation of the complex macromolecules in coal.