| OCR Text |
Show Table 2: Statistical confidence intervals for the residual iron mass of the 115 J1-m, lllinois #6 coal. T; J1- (J' 95% Conf. 99% Conf. (ms) ( -) (-) Interval Interval 6% Overall Oxygen Concentration 0.0 1.00 0.099 1.0-1.0 1.0-1.0 47.0 0.98 0.045 0.86-1.00 0.80-1.0 72.0 0.60 0.042 0.49-0.70 0.43-0.76 95.0 0.51 0.044 0.40-0.63 0.34-0.69 117.0 0.58 0.037 0.49-0.68 0.43-0.73 12% Overall Oxygen Concentration 0.0 1.0 0.099 1.0-1.0 1.0-1.0 47.0 1.16 0.049 1.0-1.0 0.96-1.0 72.0 0.50 0.035 0.42-0.60 0.36-0.65 95 .0 0.61 0.026 0.56-0.66 0.54-0.68 117.0 0.63 0.021 0.58-0.68 0.54-0.71 * approXImate, based on 100 J1-m partIcle. those predicted in this manner. The variance in the data shown in Figure 2 is given by (4) (5) where 0'; is the variance in measurement i, angle brackets represent mean values, and the remaining terms have already been defined. The partial derivatives in the expression are evaluated at the mean values of each variable. With this estimate of variance in the data, confidence intervals can be established, as shown in Table 2. Use has been made of the physical limitation of the value of Ii between 0.0 and 1.0. The variation in average iron content shown in Figure 2 is clearly larger than the experimental error in the data. That is, for both the 6 percent and 12 percent oxygen concentration levels and at both 95 and 99 percent confidence levels, the change in iron content of the particles after 50 ms residence time is larger than the uncertainty associated with the experimental procedures. The slight increase in iron indicated at residence times greater than 75 ms is not greater than the error associated with the 10 |
