GPGP Gasifier Optimization II. Task 2.2, Coal characterization by selected analytical methods

摘要

This project was undertaken by the Energy & Environmental Research Center (EERC) for the Dakota Gasification Company (DGC) in order to find out if any coal chemical characteristics correlated with gasifier performance as measured by ''Equivalent Gas Make per Equivalent Gasifier'' (EGM/EG). The measurements made on a total of 48 coal samples included ASTM proximate analysis, calorific (Btu) determination, sulfur analysis, ash fusion temperatures, x-ray fluorescence (XRF) analysis of the ash, and char-steam reactivity determination by thermogravimetric analysis (TGA). After Task 2.1 (which, again, only looked at six coal samples), two measurements were found to be very promising as predictors of gasifier performance: (1) the energy of activation of the TGA char-steam reactivity tests (E(sub a)), which had a correlation coefficient, R(sup 2), of 0.75 and (2) the difference between the hemi- and the softening temperatures in the ash fusion test, which had an R(sup 2) of 0.80. After analyzing 42 more coal samples (for a total of 48), the R(sup 2) for E(sub a) dropped to 0.33, but it was still the highest of any single measurement. As for the ash fusion test, with the additional data, the correlation of performance with the difference between the hemi- and softening temperatures all but disappeared (R(sup 2) = 0.08). One new variable, the Btu value of the coal, was found to be almost as good a predictor of performance (R(sup 2) = 0.30) as E(sub a). When the two measurements were used together, they gave the best correlation of any two variables with EGM/EG (R(sup 2) = 0.50). Thus although numerous highly significant (statistically speaking) correlations were found between coal properties and gasifier performance, whether they are strong enough to help guide plant operations is yet to be determined.