Suitability of Gray-King pyrolysis to evaluate coking pressure

Two coals of different rank and coking pressure characteristics together with a blend containing 50 wt% of each coal were employed for this study. High-temperature carbonizations in a movable wall oven of 250 kg capacity were carried out to assess the degree of dangerousness during coking. At the same time, the gas evolved during the process was condensed. In order to obtain the different layers that are formed during coking, partially coked charges were recovered from the oven. The central part of the charge was treated with organic solvents. Moreover, primary tar generated from the two coals and the blend was obtained by means of a Gray-King apparatus. The extract of the partially coked coal together with the high-temperature and the primary tars were studied by means of gas and liquid chromatography. It was found that the composition of the extract was similar to that of the primary tar, its composition depending on the coking pressure characteristics of the coals tested. By contrast, the high-temperature tar is similar for the coals and blend tested in the present work regardless of their rank or coking pressure characteristics.