A. Koch et al., A PHYSICOCHEMICAL STUDY OF CARBONIZATION PHASES .1. TARS MIGRATION AND COKING PRESSURE, Fuel processing technology, 45(2), 1995, pp. 135-153
During the coking process, the production of volatile matters, in the
plastic phase of the coking charge, leads to the development of danger
ous internal pressures if hindrance is encountered in the gas release.
By withdrawing and quenching coking coal charges at a given temperatu
re in the course of heating, several phases of carbonization were isol
ated and submitted to physicochemical analyses: diffuse reflectance in
frared spectroscopy (DRIFT), proximate and ultimate analysis, N-methyl
-2-pyrrolidinone (NMP) extraction and hydrogen transfer (HT). By these
means, two distinct ways of migration of volatile matters through cok
ing material were evidenced. For 'dangerous coals' (inducing excessive
coking pressure) the volatile materials migrate mainly from the plast
ic layer to the cold side of the oven, giving rise to impregnation of
the remaining coal. On the contrary, a large part of volatile componen
ts of 'safe' coals migrate towards the hot side of the oven through se
mi-coke and coke. These results are in agreement with our preliminary
study on the variations of the permeability of the different phases of
carbonization.