Etude du phénomène de poussée dans les réacteurs de cokéfaction en relation avec la couche plastique

Abstract : Coking pressure is known in coke industry as a phenomenon responible for coke oven damages. This phenomenon is due to the development of internal gas pressures during carbonization of coal, these pressures being induced by difficulties in volatile matter circulation. The study has been focused on two essential aspects : the different evolution stages undergone by carbonaceous material during pyrolysis, and especially the plastic phase stage ; the circulation of volatile matter (gases and tars). Five coals representative of a series of different coking pressures were selected. By quenching of coal charges at pilot as well as at laboratory scale, the circulating ways of the volatile matters during coking were identified by analyses of the different carbonization phases (raw coal, non transformed coal, plastic layer and semi-coke). By solvent extraction (N-methyl-2-pyrrolidinone), impregnation of non coked coal contiguous to the plastic layer was noted in the case of dangerous coal. Besides extraction yields, this impregnation, due to condensation of tar vapors circulating in the charge during coking, was also confirmed by other analytical techniques (infrared spectroscopy, hydrogen transfer, elemental analysis). Thus, tar circulation is mainly directed from the plastic layer to semi-coke in the case of safe coals, and from the plastic layer to non coked coal in the case of dangerous coals. This way of circulation could be due, for dangerous coals, to the choking of porous media (semi-coke) by tars of high viscosity. Complementary studies carried out on blends of safe and dangerous coals have shown a direct relation between impregnation level and coking pressure intensity. By this means, a predictive test for coking pressure was proposed
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Alain Koch. Etude du phénomène de poussée dans les réacteurs de cokéfaction en relation avec la couche plastique. Alimentation et Nutrition. Université Paul Verlaine - Metz, 1994. Français. ⟨NNT : 1994METZ008S⟩. ⟨tel-01776038⟩

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