OCR Text |
Show This expression defines the extent to which the available oxygen is utilized by C, where O-C represents twice the level of Itsaturationlt of oxygen by carbon as compared with 0 - C. As such, it therefore corresponds to the ItMechanism 2 Factorlt [ 15]. The reaction efficiency (11) is then conveniently expressed in terms of the excess air (negative when fuel rich) by 11 = 2(RCS) (1 + E%/lOO) ::. (3 .2) These expressions are not predictive unless the RCS factor is independently known, or assumed; but they can be used to infer behavior, as shown in what follows. 4. RESULTS The results given in this Section were obtained from the two sources described above, namely, the plug-flow furnace and the high-intensity reactor and furnace. These devices, therefore, represent experimental extremes of mixing conditions, with no backmix in the plug-flow furnace, and intense backmix in the high intensity reactors. All other furnace systems must, then, lie between these two extremes so far as mixing is concerned. The consistency of the results obtained from the two extreme systems is, therefore, of particular significance. 4.1 Plue-flow Furnace. Figure 4 illustrates the results obtained by Gee ~ !l [5] in a set of 15 experiments firing 1 coal and 3 petroleum cokes. The two lines are calculated independently using Eq. 3.2 assuming RCS values of 0.5 and 1. These two values represent local combustion to give: only CO for RCS = 0.5; 2 and only CO for RCS = 1.0. C.o o ) OLe -=0 The experimental results clearly lie on the line ReS = 0.5, implying that |