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

During industral coking some coals generate pressures in coke ovens that 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 that phenomena responsible for generation of coking pressure are not well understood, The aim of our work was to disclose differences in pyrolysis behavior of coals which show different coking pressure, Eight coals with coking pressure in the 1-49 kPa range were analyzed by means of 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 view that coking pressure is generated in the coal plastic layer, the results show the pressure depends on thermal decomposition in the semicoke/coke zone, The mechanism of coking pressure formation in coke ovens is presented.