A fundamental study on the pyrolysis of hydrocarbons

A newly developed detailed chemical kinetic mechanism, NUIGMech1.1, is used to study the pyrolysis of C1 – C7 hydrocarbons at a constant initial fuel concentration in the temperature range 900 – 2000 K. We observe that, for a given reaction time and pressure, fuel pyrolysis does not occur below a certain “threshold temperature”. This phenomenon is explored further in this study by performing rate of production analyses for different fuels. It is observed that pyrolysis is highly sensitive to unimolecular dissociation reactions and that the products of unimolecular dissociation determine the secondary fuel consumption pathways. Furthermore, a minimum progress of reaction factor for the initiation of pyrolysis is established for different fuels over a wide range of residence time (3 ms – 30 min) and partial pressure (0.02 – 2.00 bar) conditions. This limiting factor determines the threshold temperature for the pyrolysis of any alkane or alkene. A computer program is developed based on this concept to calculate the threshold temperature. An application of threshold temperature is also illustrated.