Feed coal

When coal is coked at a temperature of approximately 1000°C, about 70—75% of the product is coke. Nearly 20% of the product is a light gas, mostiy methane and hydrogen, that typically is used as fuel to heat the ovens. Coal tars amount to about 4% of the product and light oil or naphtha is about 1%. Ammonia is recovered in an amount equal to about 0.3% of the feed coal. The ammonia is usually converted to ammonium sulfate and sold as a fertilizer. Littie or no ammonia [7664-41-7] is produced inlow temperature carbonization (3). 

Od condensed from the released volatdes from the second stage is filtered and catalyticady hydrotreated at high pressure to produce a synthetic cmde od. Medium heat-content gas produced after the removal of H2S and CO2 is suitable as clean fuel. The pyrolysis gas produced, however, is insufficient to provide the fuel requirement for the total plant. Residual char, 50—60% of the feed coal, has a heating value and sulfur content about the same as feed coal, and its utilisation may thus largely dictate process utdity. 

Hot product char carries heat into the entrained bed to obtain the high heat-transfer rates required. Feed coal must be dried and pulverized. A portion of the char recovered from the reactor product stream is cooled and discharged as product. The remainder is reheated to 650—870°C in a char heater blown with air. Gases from the reactor are cooled and scmbbed free of product tar. Hydrogen sulfide is removed from the gas, and a portion is recycled to serve as the entrainment medium. 

Feed coal was different from that used for 482 and 521°C. 

Most coal chemicals are obtained from high temperature tar with an average yield over 5% of the coal which is carbonized. The yields in coking are about 70% of the weight of feed coal. Tars obtained from vertical gas retorts have a much more uniform chemical composition than those from coke ovens. Two or more coals are usually blended. The conditions of carbonization vary depending on the coals used and affect the tar composition. Coal-tar chemicals include phenols, cresols, xylenols, benzene, toluene, naphthalene, and anthracene. 

Immiscible wetting in mixers Sol-gel processes Pellet flocculation <0.3 Low Up to 10 ton/hr Wet processing based on flocculation properties of particulate feed Coal fines, soot and oil removal from water Metal dicarhide, silica hydrogels Waste sludges and slurries... 

In the multiple-retori. stoker, rams feed coal to the top of sloping grates between banks of tuyeres. Auxiliary small sloping rams perform... 

Although the petrochemical and metals industries were the primai y focus of the toxic air pollutants legislation, approximately forty of these substances have been detected in fossil power plant flue gas. Mercury, which is found in trace amounts in fossil fuels such as coal and oil, is liberated during the combustion process and these emissions may be regulated in the future. EPA issued an Information Collection Request (ICR) that required all coal-fired plants to analyze their feed coal for mercury and chlorine. Since these data will be used in making a regulatory decision on mercury near the end ot the year 2000, it is critical that the power industry provide the most accurate data possible. 

Perhaps the most important components of reactor solids are those that are generated during processing rather than those that are derived from inert minerals (quartz, clays) and macerals (fu-sinites, etc.) in the feed coal (74). The retention of these formed materials is more difficult to predict from the characteristics of the feed and, hence, control in liquefaction processes. 

Feed Coal Yallourn coal Lithgow coal Taiheiyo coal Mi ike coal ... 

These reactions proceed smoothly in the presence of hydrogen donating aromatic solvent (1-4) at temperatures from 400°C to 450°C, resulting in the formation of so called solvent refined coal with carbon content of 86-88% on maf basis independent of coalification grade of feed coal. 

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. 

In this work, our AIA technique was applied only to the feed coal samples. 

Pocahontas 3 low volatile bituminous coal, Illinois 6 high volatile bituminous coal, Wyodak subbituminous coal, and Beulah-Zap lignite from the Argonne Premium Coal Sample Bank were used as feed coals m these experiments. Ultimate analyses for these coals are listed in Table I. Coal samples were stored under argon in sealed ampules prior to use in pretreatment and liquefaction experiments. 

---