| OCR Text |
Show -9- 3.3 Effect of Burner Type The CEMFLAM results showed that apart from the mono-channel burner the NOx emissions were strongly dependent on the burner design. In the multi-channel burners, the relative disposition of the air streams, axial and swirl, and the p.f. stream, together with the individual momentum ratios between each channel, produce significantly different NOx emissions for equivalent total burner specific momenta. As an example, two multi-channel burner arrangements with the same total specific momentum of 2. 75 N/MW gave NOx emissions of 850 ppm and 1750 ppm, and a multi-channel burner and mono-channel burner with a specific momentum of 4.1 N/r1W produced almost equal NOx emissions. These results only serve to indicate how important the near field aerodynamics and coal particle trajectories are in the design of a low NOx kiln bUrner. · 3.4 Effect of Fuel Type 3.4.1 Coal Type The CEMFLAM trials showed that for a particular burner the NOx emissions were strongly dependent on fuel type. However, the effects were different from those observed for power station boilers where the nitrogen content of the fuel influences the final NOx emissions because of the contribution of fuel NOx. In the CEMFLAM tests, high volatile coal which had the highest nitrogen content, table 1, gave the lowest NOx emissions, whilst petroleum coke which contained the least nitrogen produced the most NOx. This effect is also observed on kilns 1 and 2. Whilst both kilns produce the same level of NOx, corrected to 0% 02, kiln 2 produces it at a lower burner momentum, so that if the momentum of kiln 2 burner were increased it would be expected to produce more NOx than Kiln 1, which is consistent with a higher proportion of petroleum coke in the fuel mix on this kiln. The CEMFLAM results suggested that operating a multi-channel burner on high volatile coal could reduce the NOx emissions to less than 500 ppm at 0% 02 on both kilns 1 and 2. Operating the current burners on high volatile coal could result in an immediate reduction in emissions of between 500 and 1000 ppm based on 0% 02. |
