An advanced coal model to predict NOx formation and carbon burn-out in pulverized coal flames
- Leeds Univ. (United Kingdom). Dept. of Fuel and Energy
There have been considerable reductions in the amount of NOx emitted by burners fired by pulverized coal in recent years. This has been brought about by a number of approaches such as reducing the temperature, or by fuel staging, both of which minimize the NOx forming reactions in fuel rich zones. Even so, this reduction in NOx is only about 60% for pulverized coal combustion and thus there is considerable interest in reducing NOx further. This is the subject of a number of collaborative research projects, such as the current UK DTI NOx project. In this paper, particular attention is devoted to pulverized coal combustion using some of the DTI-NOx project results from this laboratory. An ``advanced coal model`` based on some aspects of the work suitable for CFD modelling is outlined. In this, details of devolatilization of speciated volatiles, including HCN, are also included for a number of coals. The char left by the devolatilization process is a porous material and a model is given for the formation of chars with different morphology, namely various types of network chars and cenospheres. The implication of char topography and fragmentation on the subsequent reactions of the char is explored. Subsequent reactions of the fuel-nitrogen compounds in the char to give NOx, and the reducing effects of the unburned carbon are considered. The effect of coal composition, rank, and the nature of the nitrogen functionalities on NOx formation as well as the factors controlling residual carbon burn-out, unburned carbon, are discussed. Some consequences of this model in reducing NOx formation are considered which includes control of particle size, the choice of coal and internal reburn.
- OSTI ID:
- 324650
- Report Number(s):
- CONF-970931-; TRN: IM9911%%347
- Resource Relation:
- Conference: 14. annual international Pittsburgh coal conference and workshop: clean coal technology and coal utilization, Taiyuan (China), 23-27 Sep 1997; Other Information: PBD: 1997; Related Information: Is Part Of Fourteenth annual international Pittsburgh coal conference and workshop: Proceedings; PB: [1500] p.
- Country of Publication:
- United States
- Language:
- English
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