Experimental/modelling studies of the use of coal-based reburning fuels for NOx control

摘要

Reburning is a NO_x control technology which is gaining more widespread acceptance for application to coal-fired utility boilers. Coal can be used as a reburning fuel, however, more detailed understanding is needed of how coal properties impact its performance as a reburning fuel, and ultimately, how these properties impact boiler performance. This paper describes the results of an experimental and modelling study designed to provide this understanding. In this study, different pulverized coals were evaluated as potential fuels for reburnign applications in coal-fired utility boilers. Ten coals were tested in a small pilot-scale facility designed to simulate representative boiler ocnditions, and with sufficient flexibility to cover an effective range of process parameters. Results of the study have confirmed the viability of coal as a reburning fuel. The sub-bituminous and lignitic coals tested showed the potential to achieve high levels of NO_x control, while performance with bituminous coals tended to be related to fuel nitrogen content and volatility. With all coals reburning performance was also found to be strongly influenced by available residence time and by initial NO_x levels. Existing reburnign process models and boiler performance models were adapted to accommodate the coal reburning data, and these models were ued to extrapolate performance to possible utility boiler applications.