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I Technical Data for Coal Pyrolysis This appendix contains tables indicating properties of products from various coal pyrolysis processes. 191

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APPENDIX I TABLE I-2 Summary of Operating Condition Effects on Liquid Yields and Quality from Coal Pyrolysis 193 Liquid yields are maximized with high-volatile bituminous coals, and lower- rank coals yield gases and tars with higher oxygen content than bituminous coals. The degree of primary devolatilization (gases + liquids) increases with increas- ing temperature, but the distribution of gases and liquids depends on secondary reactions of devolatilization products. For a given reactor system, higher temperatures result in tars cracking to gases and secondary char, the loss of aliphatic side-chains from condensibles, a lower heteroatom content in the condensibles, a higher pitch content in the condensible product, higher BTX (benzene, toulene, xylene) yields, and lower PCX (phenols, creosols, xylenols) yields. Char volatile matter and sulfur content decrease with increasing temperature. Carbon oxides in the fuel gas product increase with temperature. In inert atmosphere, condensible product yields tend to decrease with increasing pressure, but in a reactive atmosphere (water, hydrogen, carbon dioxide) conden- sible yields tend to increase with increasing pressure. Reactive gases may inhibit secondary reactions of volatiles, which results in increased condensible yields. Particle heating rates by reactor type generally follow the trend: fixed bed moving bed < fluidized bed ~ entrained bed. Slow heating favors secondary reactions of volatiles within coal particles, which results in lower overall condensible yields, more aliphatic components, a lower pitch content in the condensible product, and a composition tending to be richer in thermodynamically stable products. Fast heating favors more rapid release of tars into the gas stream, which results in higher overall condensible yields, a more highly aromatic condensible product, a higher pitch content in the tar, and a product character that tends to be determined by devolatilization kinetics. Larger coal particles tend to favor secondary reactions within particles, producing the same results as slow heating rates. Sulfur-capture additives such as CaO and Fe2O3 can reduce the H2S content of product gases by several orders of magnitude, but they provide catalytic surfaces that tend to promote cracking reactions of condensibles. Sulfur-capture additives also reduce volatile products yield and consume carbon from the coal feed; stream pretreatment below devolatilization temperatures may enhance condensible yields. SOURCE: Wootten et al. (1988~.

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194 APPENDIX I TABLE I-3 Comparison of Typical Condensibles from Coalite and Occidental Flash Pyrolysis Process Coalite Occidental Property of Tar Run no. N/A 175 Yield (wt% dry coal) 9.0 25.0 Specific gravity 1.029 1.143 Moisture (wt%) 2.2 (mar) Ash (wt%) 0.1 (maf) Elemental Analysis mof wt% Carbon 84.0 78.8 Hydrogen 8.3 7.1 Sulfur 0.74 1.7 Nitrogen 1.08 1.8 Oxygen 5.78 10.6 Hydrogen-to-carbon atomic ratio 1.18 1.07 Toluene-insolubles 1.2 18.0 Distillation Range (F) Cumulative wt% <550F 44 10 551-680F 67 25 680F end point N/A 49 Total Pitch (qt. percent of tar) 26.0 53.3 NOTE: mar = moisture and ash free. SOURCE: Wootten et al. (1988~.

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