Prediction of Pyrolysis Products and Yields from Brown to Semi-Anthracite Coals by Using Elemental Composition

Abstract

A coal pyrolysis experiment under atmospheric and elevated pressure conditions using a thermobalance is carried out to clarify the yields of devolatilization products in many coals (i.e., coal ranks from low [C :73.1wt%, daf] to high [C: 90.6 wt%, daf, semi-anthracite]) and to clarify the effect of pressure on pyrolysis yields (tar and gas yields). As a result, a method for predicting the product yields of many coals is presented. Even coal containing almost the same percentage of carbon varies greatly in yield of volatile components and/or tar, but the use of H/C and O/C allows for systematic sorting. The yields of volatile and tar increase almost linearly with increasing H/C. CH4 and C2H4 yields also increase with increasing H/C. The yield of heavier gases such as C2H6, C3H6, and C3H8 cannot, however, be sorted by H/C. CO2 and CO yields are predictable since they increase linearly with increasing O/C. The yields of devolatilization products can be estimated with favorable accuracy for many types of coal by H/C and O/C. In addition, the tar yield decreases and the total yield of gas shows increasing behavior at elevated pressure conditions in all types of coal.