OCR Text |
Show - 5 - contribution of char nitrogen to the total NOx emissions in staged flames. The burnouts of the blends were observed to exhibit a non-linear relationship with respect to the blending ratio. Results indicated that the higher reactivity coal in a blend is preferentially burnt at the expense of the lower reactivity coal. It was concluded that the addition of a reactive coal to a less reactive coal would not necessarily result in an improvement in burnout. Co-firing of Shreded Straw with Pulverised Coal For these experiments, the burner design allowed for two different modes of operation, i.e. injection of the straw through a central orifice or through an annul us surrounding the coal channel. Three different coals were tested as shown in Table 1. These were a regular HVB coal, a regular MVB coal and a high sulphur HVB coal. The measurements were primarily input-output measurements. The output measurements consisted of flue gas temperature and composition and pollutants (C02, CO, 02, NOx, S02, HCI), heat flux profiles and burnout. The input process variables studied during the experiments were co-firing ratio, swirl level, excess air level, and straw /paper injection mode and velocity. The first part of the experimental campaign was executed in May 1993. The main parameters observed to affect the flue gas composition were the co-firing r<ltio, coal type, burner staging and excess air |