OCR Text |
Show Three d ifferent fuels were fired : a high volatile bituminous coal, a medium volatile bituminous coal and a petroleum coke. The thermal input was maintained throughout the experiments at 2.5 MW. Combustion air temperatures varied between 800 and 1000oC. Preliminary results of the study indicated that nearburner field mixing was dominant in deterIl'\ining fuel NOx and carbon monoxide enusslons, although overall mixing and 1800 1600 1400 o 1200 t... ~ ~ 1000 I! !. e 800 ~ iii ~ 600 400 200 0 0 , • HVl201ft 110 aV' Or2.4 o NYl2K 90 mi. 0,.1.3 • 10 Figure 8. Effect of coal type and velocity . on wall temperature distribution u flame characteristics created by variations in burner parameters were also observed to be of extreme importance for NOx and efficiency. A typical wall temperature distribution from the Mono-channel burner is shown in Figure 8. The results of the CEMFLAMEI investigation have been fully reported to the Consortium, but have not- yet been reported in the public domain. A presentation made to the British Flame Research Committee, Flame Days at Sheffield [7], indicated that for the two burner types under consideration clear recommendations have been developed on how the burners may be designed/modified to reduce NOx and maintain heat transfer. In Consortium meetings since that time, a number of members have indicated examples of application of these results leading to significant improvements in combustion systems operation. Meanwhile, further research programmes are in discussion with the : consortium. An area where it is foreseen that further programmes may be i developed concerned the utilisation of biomass materials and disposal of I wastes, in cement kilns. Initially similar work is being undertaken, but related to the major alternative combustion system, namely utility ~oilers. 5. CO-FIRING OF BIOMASS AND WASTE MATERIALS WITH PULVERISED COAL Where it is technically and economically feasible, -the co-firing of waste biomass with pulverised coal in the power generation industry can help to |