A PHYSICOCHEMICAL STUDY OF CARBONIZATION PHASES .3. A METHOD OF PREDICTING WALL-PRESSURE BY EXTRACTION WITH N-METHYL-2-PYRROLIDINONE

Previous experiments carried out on several carbonization phases at la boratory and pilot scales have shown a relationship between the migrat ion of tar, evidenced by extraction with N-methyl-2-pyrrolidinone (NMP ), and the coking pressure. In the present study, complementary experi ments using similar analytical techniques confirm that the impregnatio n of non-transformed coal by recondensed tars is related to the wall p ressure that develops during pyrolysis. The results obtained on partia lly coked coal charges in a laboratory oven permit the simulation of t he evolution of impregnation versus the blending ratio of binary blend s. Compared with pilot-scale measurements of the wall pressure on vari ous blends, this evolution of impregnation appears to be directly rela ted to the wall pressure. On this basis, a predictive laboratory test of wall pressure evaluation through solvent extraction is proposed.