Bituminous coals sulfur contents

Properties. Pilot-unit data indicate the EDS process may accommodate a wide variety of coal types. Overall process yields from bituminous, subbituminous, and lignite coals, which include Hquids from both Hquefaction and Flexicoking, are shown in Figure 14. The Hquids produced have higher nitrogen contents than are found in similar petroleum fractions. Sulfur contents reflect the sulfur levels of the starting coals ca 4.0 wt % sulfur in the dry bituminous coal 0.5 wt % in the subbituminous and 1.2 wt % sulfur in the dry lignite. 

Properties. A high volatile western Kentucky bituminous coal, the tar yield of which by Fischer assay was ca 16%, gave a tar yield of ca 26% at a pyrolysis temperature of 537°C (146—148). Tar yield peaked at ca 35% at 577°C and dropped off to 22% at 617°C. The char heating value is essentially equal to that of the starting coal, and the tar has a lower hydrogen content than other pyrolysis tars. The product char is not suitable for direct combustion because of its 2.6% sulfur content. 

A primary concern in coal-fired power generation is the release of air pollutants. Limits on SO2 output, 0.52 g/MJ equivalent of coal input to a new plant, have been estabflshed. Eor a bituminous coal of 27.9 MJ/kg there is thus an upper limit of 0.72% sulfur content. Relatively few coals can meet this requirement. The U.S. Department of Energy indicated recoverable reserves of 420 x 10 t in 1987 (2) that were categorized by sulfur content 33.5% had 0.6% S or less, 15.4% had between 0.61% and 0.83% S, 16.1% had between 0.84 and 1.67% S, 12.4% had between 1.68 and 2.50% S, and 22.6% had more than 2.5% S. The lowest sulfur coal, 86%, is found west of the Mississippi River, mainly in Montana and Wyoming, quite distant from the electric power demand centers in the East. A trend to utilization of the western coals has developed. 

The main purpose of magnesia addition to a limestone wet scrubbing system is to facilitate high S02 removal. For a wet scrubber that cleans flue gas from a utility coal-fired boiler, the scrubber inlet gas S02 concentration is typically about 700 ppm by volume per one weight percent sulfur in the fired coal. For sub-bituminous coal having only 0.7 weight percent sulfur content, the inlet S02 concentration is about 500 ppm, and, for example, the outlet S02 has to be less than 50 ppm to achieve 90 percent removal. In order to avoid serious inhibition of mass transfer because of S02 back-pressure, the equilibrium S02 partial pressure should be about four or more times lower than the actual S02 partial pressure in the gas. Thus, Figure 3 indicates that for this low-sulfur coal system, the scrubber inlet pH should be at least 5.5, and the outlet pH at least... 

Two bituminous coals of moderate ash content were chosen for this paper to illustrate this method of determining coal-mineral association. The first sample was an Upper Freeport coal with 1.3% moisture, 9.88% ash, and 1.56% total sulfur. The second sample was an Indiana No. 3 coal having 10.5% moisture, 7.35% ash, and 4.26% total sulfur. Both coals had been precleaned at a coarse particle size, ground to minus 325 mesh (44 ym), and then separate samples were cleaned by float-sink and by froth flotation techniques, as described elsewhere [5]. Analyses of the feed coals are included in Table I. 

H/C = atomic hydrogen-to-carbon ratio V = vitrinite content of coal VM volatile matter St = total sulfur TRM = total reactive macerals The adequacies of these reactivity correlations, expressed as a percentage of the total variation in the data set explained by the model, were 80.0%, 79.2%, and 47.5% respectively. A later paper in the series (21) concentrated on the development of reactivity correlations for a set of 26 high volatile bituminous coals with high sulfur contents, and extended the models previously developed in include analyses of the liquefaction products and coal structural features. These structural features included the usual... 

Table III lists the specific gravity, nitrogen content, and sulfur content of the various distillation fractions obtained from each of the eight coal liquids. Nitrogen content increased for the higher-boiling distillates as expected. All sulfur values were low as expected. Nitrogen contents of the asphaltenes from the bituminous-coal liquids were higher than those from the lower-rank-coal liquids.

The proposed NSPS can be met by hydrotreating the coal liquids obtained by filtering the product from the coal dissolution stage. The desulfurization kinetics can be presented by two parallel first-order rate expression, and hydrogen consumption kinetics can be presented by a first-order rate expression. A linear relationship exists between total sulfur content and SRC sulfur content of the hydrotreated product. For the Western Kentucky bituminous 9/14 coal studied here, the maximum selectivity and lowest SRC conversion to oil for a fixed SRC sulfur content are obtained using the highest reaction temperature (435°C) and the shortest reaction time 7 min.). ... 

Tires are a good fuel for several reasons. Tires contain about 15,000 Btu s per pound (about 300,000 Btu s per tire). Coal heating values range from 6,000 to 13,500 Btu s per pound. Further, they are compact, have a consistent composition, and contain a low moisture content. Also, many components of tires, such as sulfur and nitrogen, compare favorably to coal in percent makeup. Table 1-2 compares composition of tires to that of midwest coal.4 Table 1-3 compares composition of various types of tires.5 Most trace metal levels in tires are equivalent to the levels in coal zinc and cobalt are higher in tires.6 Figure 1-1 shows trace metal level of whole tires compared to bituminous coal.6... 

Rasa coal is exceptional because of its high sulfur content, most of which appears to be organic sulfur. The high organic sulfur content is characteristic of marine-influenced bituminous coals. Rasa coal appears to have been formed in a high-pH marine environment where bacteria thrived. This hypothesis is supported by the presence of substantial amounts of both calcite and dolomite in Rasa coal. The calcium- and magnesium-rich environment where Rasa coal formed is expected to have been alkaline. The... 

This motivates the present work. Two coals of high organic sulfur content and low pyritic sulfur content were chosen for study a lignite (Spanish Mequinenza) and a high volatile A bituminous coal (New Zealand coal from the Charming Creek mine). 

Various bituminous coals were demineralized by an experimental two-step leaching process in which the ball-milled coals were first treated with a hot alkaline solution and then with a dilute mineral acid. Different alkalis and acids were studied to determine their relative effectiveness. In addition, the effects of alkali concentration, treatment temperature, and treatment time were evaluated. Under the best conditions, the process reduced the ash content of the coals by 85-90% and the total sulfur content by 70-90%. As the temperature of the alkaline treatment was raised from 150 to 345 C, the removal of sulfur increased greatly whereas the recovery of organic matter declined. When a 1 M sodium carbonate solution was employed for the treatment, the recovery of organic matter was 91-97% for various coals treated at 250 C and 79-89% for the same coals treated at 300 C. 

Some work has been reported utilizing alcohols for supercritical extraction of coal. Makabe et al.(5) reported extraction of coal with ethanol-sodium hydroxide mixtures with the objective of maximizing extraction yield no sulfur data were reported. Methyl alcohol reaction with a low volatile bituminous West Virginia coal at higher temperatures (460-600 °C) was reported by Garner et al.(J>). Promotion of coal gasification was the objective of that study sulfur content of the resultant char was not reported. 

Table I. Bituminous Coal Samples and Their Pyritic Sulfur Content...

Another slurry pipeline desulfurization experiment was conducted using Indiana 3 (Ayrshire) coal as a 25 wt% slurry in deionized water. The other process variables were carefully controlled flow rates 6-6.5 ft/sec, temperature 70-90°F, and pH 2.5 -2 8.The experiment was continued for 14 days, and the slurry samples for pyritic sulfur determination were taken daily. The desulfurization rates with Indiana 3 coal in the pipeline experiment are shown in Table 4 and are in good agreement with the laboratory data and the results with Illinois 6 coal. As observed in the laboratory experiments, the rate of desulfurization of bituminous coals is directly proportional to the pyritic sulfur content and inversely to the particle size of the coal sample. 

The organic sulfur content in the Wyodak subbituminous coal is unaffected by increasing reaction severity while the types of organic sulfur compounds in the Monterey bituminous coal are removable as reaction severity is increased. 

As a fuel, the most common uses of petroleum coke are in firing cement kilns and steam generators. In the cement industry, petroleum coke is suitable as fuel in kilns because of its low ash content, high heating value and the process s high sulfur allowances. As much as 50% coke can be burned in combination with bituminous coal or 75% coke when burned in combination with Oil and/or gas. 

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