Role of char during reburning of nitrogen oxides. First quarterly report, October 1, 1993--December 31, 1993
Customarily, coal and lignite have not been considered viable reburning fuels for a number of reasons. NO reduction through homogeneous gas phase mechanisms is generally believed more important than the heterogeneous NO reduction on char; and coal devolatilization in the fuel rich environment generates only about 50% of the volatile hydrocarbon radicals than gaseous hydrocarbons under the same fuel-to-oxidant stoichiometry. In addition, the fuel nitrogen could result in additional nitrogen oxide emissions in the burnout stage. What has not been anticipated is the highly active nature of lignite char surface. First, it has been demonstrated in the literature that lignite char can be gasified by nitrogen oxide; second, the minerals in lignite char can catalyze the CO + NO and gasification reaction; and third, lignite char has a highly porous structure which is desirable for gas/solid reactions. The unique NO activity on char surface is expected to benefit the utilities which are involved in coal combustion and have to meet the stringent Clean Air Act Amendments of 1990. This program is aimed at a better understanding of the chemical and physical mechanisms involved in the reburning with chars. Char gasification rates will be measured with and without the presence of CO. Further, the rate of the char catalyzed CO + NO reaction will also be measured. Experiments have been conducted with a flow reactor which simulates the reburning stage. One bituminous coal and two lignites, one from North Dakota and the other from Mississippi, are used in these tasks. A unique component of this program is the use of the fractal concept in the estimations of these gas/solid reaction rates. The proposed program is designed to investigate the relative importance of these two reactions (char gasification and ash catalyzed CO + NO reactions) under reburning conditions.
- Research Organization:
- Mississippi Univ., University, MS (United States). Dept. of Chemical Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-93PC93227
- OSTI ID:
- 10133918
- Report Number(s):
- DOE/PC/93227-T1; ON: DE94008361; BR: AA1525050
- Resource Relation:
- Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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