Formation of NH{sub 3} during the pyrolysis of a brown coal

Conference · Thu Dec 31 04:00:00 EST 1998

OSTI ID:349215

Li, C Z; Pang, Y; Li, X G ^[1]

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1. Monash Univ., Clayton, Victoria (Australia). Dept. of Chemical Engineering

Emissions of oxides of nitrogen (NO, NO{sub 2} and N{sub 2}O) from power generation using coal are an important environmental problem, contributing to the formation of photochemical smog and acid rain or to the enhancement of greenhouse effects and to the enhanced depletion of stratospheric ozone. During pyrolysis, the nitrogen in coal, as a part of coal organic matter, is converted into NOx precursors (eg. NH{sub 3}, HCN, HNCO and the nitrogen in tar and char). These NOx precursors may then be converted into either NOx or N{sub 2} during subsequent combustion or gasification/combustion. The conversion efficiency of these NOx precursors into NOx depends strongly upon the type of NOx precursor. Knowledge of the formation of these NOx precursors during pyrolysis is therefore essential for the accurate predictions of NOx emissions from large scale power plants, and therefore for the development of optimum strategies for NOx reduction. Formation of NH{sub 3} during the pyrolysis of a Victorian brown coal (Loy Yang) has been studied in a novel reactor. The experimental results obtained suggest that a considerable amount of the nitrogen in the nascent char could be converted into NH{sub 3} if the char is held at high temperatures for a long period of time. The formation of NH{sub 3} from the thermal cracking of char was seen to last for more than an hour even at temperatures as high as 700--900 C. The experimental results seem to suggest that the differences in reactor geometries would account at least partially for some of the discrepancies in the literature regarding the formation of NH{sub 3} during the pyrolysis of coals. It is thought that NH{sub 3} may be formed from the hydrogenation of the N sites in the char by the active hydrogen generated from the thermal cracking of the char.

• OSTI ID: 349215
• Report Number(s): CONF-980985--; ISBN 1-890977-15-2
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
20 FOSSIL-FUELED POWER PLANTS
AIR POLLUTION CONTROL
AMMONIA
BROWN COAL
CHEMICAL REACTION YIELD
COMBUSTION KINETICS
FOSSIL-FUEL POWER PLANTS
NITROGEN OXIDES
PYROLYSIS