关键词: devolatilization;char reactivity;slagging;NOx;coal

Abstract: Seven Chinese coals ranking from anthracite to sub-bituminous from the Shanxi province were
selected for study to forecast the combustion and NOx emission behavior. Three UK, one
Indonesia and one South Africa coal was included in the study for reference. A flat flame-
turbulent jet apparatus was employed to assess flame stability, ignition performance and
NOx emission behavior for the initial stage of devolatilization and combustion.This
apparatus can simulate particle heating rates, maximum temperatures and the influence of
the turbulent fluid interactions on the fate of volatiles. To simulate processes occurring
over longer residence time, additional devolatilization experiments were performed in a
drop tube furnace. Char reactivity was studied through thermogravimetric analysis. Finally,
fouling propensity was studied with the aid of a purpose-built laboratory combustor that
enabled the characteristics of the ash deposit to be assessed empirically. The results show
that Chinese coals do not appear to possess unusual features in respect of NOx formation,
flame stability and ignition, char burnout and ash slagging. The range of coals available
in China appears sufficiently broad that suits all requirements. In particular, Shenfu
coal, with its initial fast devolatilization and nitrogen release rates and its low initial
nitrogen content and high char reactivity, will perform well when fired in industrial
boilers as far as NOx emission, flame stability and combustion efficiency are concerned.
Pingshuo coal exhibits high char reactivity and an attractive slagging performance
suggesting that this fuel represents a good compromise between NOx emission and overall
plant efficiency.

Key words: devolatilization, char reactivity, slagging, NOx, coal