Experimental study on kinetic characteristics of oil sludge gasification

Oil sludge (OS) is a typical dangerous waste in petroleum industry, which also contains abundant energy. The purpose of this study was to recover resources from OS gasification. To figure out the gasification process, a thermal analyzer was used to carry out OS gasification experiments under steam/nitrogen atmosphere with different heating rates. Results showed that the OS gasification reaction could be divided into five stages: free water volatilization, the escape of light components, the cracking of heavy components and steam reforming, the charring process and water gas shift (WGS) reactions, and inorganic mineral decomposition. The activation energy (E), pre-exponential factor (A), enthalpy change (Delta H), Gibbs free energy change (Delta G), and entropy change (Delta S) of three main reaction stages (Stages 2-4) were analyzed through kinetic and thermodynamic analysis. From Stage 2 to Stage 4, E, Delta H, and Delta S decreased from 118.80 kJ.mol(-1), 113.92 kJ.mol(-1), and -4.09 J.(K mol)(-1) to 13.19 kJ.mol(-1), 5.92 kJ.mol(-1), and -234.06 J.(K mol)(-1), respectively. Nevertheless, Delta G increased from 116.01 to 210.04 kJ.mol(-1). From these parameters, it could be found that the decrease of E was beneficial to the reaction. However, the values of Delta G were always positive and the reaction could not happen spontaneously.