OCR Text |
Show 6 sensor. Combustion intensities exceed 10 Btu/cu.fL.hr. even with partial combustion, compared with about 20,000 Btu/cu.ft.hr. in normal flames. In a series of experiments this has been used to investigate the combustor behavior in the reactor [6]. It has also been used to determine conditions required for extinction at the rich and lean limits and when using chemically inactive or active additives [7]. The combustion efficiency with the jet-mix reactor was typically about 65%, split in varying proportions between volatiles and fixed carbon, depending on stoichiometry [6,7]; and reaction time was mostly in the range 10 to 20 msec. The high-intensity furnace was designed to extend the results obtained in the jet-mix reactor, in particular by determining the total time for burnout. The top-section of the furnace essentially reproduced the jet-mix design, using 4 opposed jets to supply and mix the incoming coal. Secondary air was supplied in the same way below the initial mixing section. Under most rapid mixing conditions bum-out time was found to be about 100 msec [8], even with massive water injection [9]. In further experiments with significant time delay between staging (up to 50 msec) [10,11], reactivity dropped, evidently on account of heat treatment, and bum-out times increased to exceed an estimated 1 second. Further details of the experimental methods and results are given in the citations. 3. MATERIALS BALANCE: THE RELATIYE CARBON SATURATION FACTOR The detailed behavior in a flame is, in principle, predicted by appropriate flame codes, as described in earlier papers [13,5]. Substantial inferential information can be obtained, however, from a simple materials balance at any point in the flame. This is aided by use of the Thring [14] Relative Carbon Satuation Factor (RCS). This factor is particularly useful under fuel-rich conditions. The RCS factor is defined by the expression RCS = -«€t)%] + [CO %])1(2 - [C6%]I100)[O %]) 2 2 (3.1) |