BASIC PHENOMENA RESPONSIBLE FOR GENERATION OF COKING PRESSURE - FIELD-IONIZATION MASS-SPECTROMETRY STUDIES

During industral coking some coals generate pressures in coke ovens th at are too high which leads to troubles in operation and shortens coke oven life, Conventional coal testing methods are not capable to fully eliminate ''dangerous'' coals from processing. The major reason is th at phenomena responsible for generation of coking pressure are not wel l understood, The aim of our work was to disclose differences in pyrol ysis behavior of coals which show different coking pressure, Eight coa ls with coking pressure in the 1-49 kPa range were analyzed by means o f pyrolysis-field ionization mass spectrometry (Py-FIMS). The results indicate that coking pressure is related to (i) the yield of pyrolysis products generated in the 470-700 degrees C range and (ii) individual composition of the pyrolysis products, Thus, in spite of the common v iew that coking pressure is generated in the coal plastic layer, the r esults show the pressure depends on thermal decomposition in the semic oke/coke zone, The mechanism of coking pressure formation in coke oven s is presented.