An Attempt to Correlate Conversions in Pyrolysis and Gasification with FT-IR Spectra of Coals

Pyrolysis and gasification data from two different laboratory reactors have been correlated with results predicted from FT-IR spectra of a set of 26 coals by a statistical data analysis package. Despite the diversity in geological origins of the samples, excellent agreement was obtained between predicted weight loss values and pyrolysis total volatile yields determined in a wire-mesh reactor. Agreement was poor between predicted values and data from a fixed-bed reactor, where the geometry of the reactor appears to have behaved as an interfering variable. The design of the wire-mesh reactor is intended to minimize the effect of reactor geometry on coal pyrolysis yields. This interpretation suggests that the statistical procedure used in this work is capable of leading to predictions of coal pyrolysis yields that may be perceived as physically meaningful. The level of agreement suggests that the initial structures of coals (as reflected in their infrared spectra) are related to their pyrolytic behavior. The method used in this work seems appropriate for estimating volatile matter yields of "unknown" power-station coals under pf-combustion conditions, if a complete set of 1500 degrees C pyrolysis data are carried out on the "calibration" set in a wire-mesh reactor. However, predictions for conversions in CO2-gasification experiments were poor. FT-IR spectra of coals as the starting point does not seem to be a viable route for reliably predicting CO2-gasification reactivities. Experimentally, the major part of the actual gasification process appears to take place between the reactive gas and the post-pyrolysis char, which has very different properties.