Experimental investigation on physical and chemical properties of solid products from co-pyrolysis of bituminous coal and semi-coke
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Bituminous coal
Solid fuel
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The Clean Coke process is being developed by United States Steel Corporation under contract with ERDA's Office of Coal Research to provide a means for utilizing the nation's abundant reserves of low-grade, high-sulfur coal to produce metallurgical coke, chemical feedstocks, and liquid and gaseous fuels. The basic process combines low-temperature carbonization of coal and hydrogenation-liquefaction of coal to provide an energy- and hydrogen-balanced process; all operations are conducted in closed loops, which eliminate either escape or discharge of pollutants to the environment. Results are summarized of studies on carbonization of Illinois No. 6 seam coal in a fluidized bed to produce low-sulfur char. The carbonization char is subsequently combined with a process-derived liquid binder to form green pellets, which are then cured and finally calcined to produce metallurgical coke pellets. This study includes results on the effects of carbonization variables--temperature, pressure, reaction time, and feed pretreatment--on the desulfurization reaction and on operation of the fluid-bed carbonizer. Under optimum conditions, coal containing 2.3 percent S was carbonized to produce a char containing less than 0.5 percent S.
Destructive distillation
Bituminous coal
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Experimental analysis of the lignite pyrolysis characteristics of Inner Mongolia Baiyinhua lignite was carried out in tube furnace,the structure of the raw coal and solid pyrolysis products of semi-coke composition changes had been investigated.The adsorption/desorption isotherms of raw coal and semi-coke obtained under different carbonization conditions showed that the semi-coke had a wide pore size distribution,and mesopore and micropore account for a substantial proportion;the semi-coke pore characteristics showed the final dry distillation temperatures and holding time of lignite pyrolysis had a significant impact on specific surface area,pore volume and average pore diameter of semi-coke.
Dry distillation
Destructive distillation
Tube furnace
Specific surface area
Charcoal
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Describes continuous, entrained-bed carbonization of an Australian bituminous coal containing 5.5 percent moisture and 12.6 percent ash in an 8-inch-diameter reactor at 960/sup 0/ to 1,300/sup 0/F and at air-to-coal ratios of 6.74 to 13.16 standard cubic foot per pound of moisture- and ash-free coal charged. Carbonization rates from 138 to 287 pounds per hour (as-carbonized basis) were achieved without prior oxidation of the coal or char recirculation. Yields of char ranged from 60.2 to 68.5 percent of coal charged (as-carbonized basis), and yields of tar plus light oil ranged from 11.3 to 16.1 percent of coal charged (as-carbonized basis). Volatile matter in the char produced ranged from 8.7 to 17.9 percent.
Bituminous coal
tar (computing)
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Using bench- and pilot-scale coking facilities, the Bureau of Mines produced experimental coke from blends of char with Sunnyside coal (high-volatile A bituminous) from Carbon County, Utah. At bench scale, additions of char made from lignite improved resultant cokes when concentrations of up to 60% were used in the blends. At pilot scale (500-lb movable-wall oven), four chars made by entrained-bed carbonization techniques from the parent Sunnyside coal and from a North Dakota lignite were used in two-component blends with the Sunnyside coal. Chars from Sunnyside coal had volatile matter contents of 5.8, 9.8, and 16.0%, moisture-free basis; the char from the lignite had 16.6%. In twenty-five 500-lb tests, improvement in coke quality was observed from all blends at char concentrations to 17.5%. The best coke, produced from a concentration of 12.5 to 15% of 5.8% volatile char, exhibited physical properties approaching those of an industrial coke produced from Sunnyside coal blended with three higher rank blending coals. Studies were also made of the effects on coke quality of char source, of particle size, of comparative use of char and of a blending coal, and of prolonged coal storage.
Bituminous coal
Carbon fibers
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Thermogravimetric experiments were performed to study the pyrolysis characteristics of two kinds of lignite and one bituminous coal at the low temperature.The main work was done to investigate the influence of the heating rate and holding time on pyrolysis process.It indicates that there are more influences on Indonesia coal because of the extension of holding time at 500 ℃ and a more obvious reduction of Yunnan coal at 600 ℃.The higher heating rate the more remarkable weightlessness peak is.The characteristic parameter and kinetic parameters of coal pyrolysis reaction were obtained based on thermogravimetric experiment.
Thermogravimetric analysis
Bituminous coal
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Bituminous coal
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Carbon fibers
Bituminous coal
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The present study focuses on examining the fate of coal-S and coal-N during carbonization in detail and making clear the effects of these elements on coal fluidity and coke strength. When eight kinds of caking coals with 80–88 mass%-daf C are carbonized in high-purity He at 3°C/min up to 1000°C with a quartz-made fixed bed reactor, 50–75% of coal-S remains as FeS and organic-S in the coke, and the rest is released as tar-S and H2S. Most of coal-N is also retained in the coke, and the remainder is converted to tar-N, HCN, NH3 and N2. The eight coals give Gieseler maximum fluidity values between 435 and 480°C, and the value tends to be larger at a smaller sulfur content in coal or in the carbonaceous material recovered after carbonization at 450°C. It also seems that the value increases with increasing nitrogen content in coal or total amount of either HCN or NH3 formed up to 450°C. Furthermore, the addition of S-containing compounds to an Australian bituminous coal lowers coal fluidity and coke strength considerably, whereas indole gives the reverse effect on them. On the basis of these results, it is suggested that coal-S or some coal-N has a negative or positive effect on the two properties, respectively.
Caking
Bituminous coal
Coal tar
tar (computing)
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Middle-temperature pyrolysis is widely used to convert sub-bituminous coal into gas/liquid products and the coal char, which benefits the utilization of low rank coal resources. However, the coal char usually contains high-ash content because the volatile components in coal release from coal particle forming gas/liquid products while most of high-ash mineral components remain in the coal char. Therefore, the upgrading of the coal char is usually required to meet the requirement of calorific value for burning. It is necessary to find out the effect of middle-temperature pyrolysis on the surface hydrophobicity of coal. In this study, the effects of pyrolysis temperature (700, 800, and 900°C) and pyrolysis time (30 and 90 min) on the surface hydrophobicity of sub-bituminous coal were comprehensively investigated. X-ray photoelectron spectroscopy (XPS), attachment time, and flotation tests were used to reveal the changes of surface hydrophobicity and floatability of sub-bituminous coal before and after middle-temperature pyrolysis. The XPS results indicated the content of hydrophilic oxygen-containing functional groups was reduced while the content of hydrophobic functional groups on coal surface was increased after the pyrolysis. The attachment time of coal particle-bubble was reduced while the flotation recovery of coal was increased after the pyrolysis. The surface hydrophobicity and floatability of sub-bituminous coal were enhanced by middle-temperature pyrolysis, which makes the upgrading of the coal char feasible.
Bituminous coal
Destructive distillation
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