AUTOCORRELATIONS OF KINETIC-PARAMETERS IN COAL AND CHAR REACTIONS

For a wide range of coal reactions, the values of the preexponential constants (k0) and activation energies (E) are shown to be so highly correlated that the presumption is that they are autocorrelated. The reactions involved include total pyrolysis; pyrolytic release of tar, hydrocarbons, and low molecular weight gases; volatile combustion; and char-gas reactions. The presumption of autocorrelation is supported by a simple analysis based on the assumption that variations in k0 and E are a statistical consequence of random errors of measurement, and this carries the associated inference that the primary rate measurements belong to a common data set in spite of the wide range of k0 and E values extracted (often by different procedures in data reduction). This conclusion also implies such a surprising degree of commonality in the two main reaction groups (pyrolysis and char-gas reactions) that requires the reactions to be substantially independent of coal rank. © 1990, American Chemical Society. All rights reserved.