Effect of Water Vapor on the Oxidation of Heavy Fuel and Vacuum Residue Oil in a Tga

Abstract

The effect of water on the oxidation of two residual fuel oils (heavy fuel oil (HFO) and vacuum residual oil (VRO)) was investigated in a thermogravimetric analyzer (TGA). The oxidation process was investigated by monitoring the mass profiles in a wide range of conditions. The TGA experiments cover temperatures range from ambient to 800 °C, heating rates of 5, 10 and 15 °Cmin-1, and various oxygen and water concentrations. The results show a noticeable effect of water on the oxidation process of the two fuels, especially in the fuel deposition region, where the presence of water accelerates the mass decay. Kinetic analyses were performed using a model-based method, Coats and Redfern to investigate the reaction schemes in different temperature regimes. First order, 1-D diffusion and assumed random nucleation and growth mechanisms were found to capture the oxidation of HFO and VRO in different temperature regimes. Apparent kinetic parameters evaluated also exhibited a noticeable effect of water vapor on the oxidation of both fuels.

Keywords: Thermogravimetric analysis, Vacuum residue oil, Heavy fuel oil, Oxidation under water vapor, Reaction zones, Apparent kinetics