On the products from the pyrolysis of heavy fuel and vacuum residue oil

Abstract

Incorporating unconventional fuel sources into the global energy mix is necessary to meet increasing energy demand. One attractive option is the gasification of residual fuels, such as heavy fuels, which produce clean combustible gases. Pyrolysis is the first step in the gasification process, so its understanding can help in the development of the gasification process. The information on the pyrolysis products can serve the development of chemical kinetics mechanisms for gasification of heavy fuels for their efficient utilization. In this study, pyrolysis of heavy fuel oil (HFO) and vacuum residue oil (VRO) is reported. The pyrolysis experiments were conducted in a wide temperature range of 400–1000 °C in a customized tubular furnace-based reactor and products were collected. Both liquid and gaseous products were characterized using a gas chromatography (GC)-mass spectrometry (MS)-flame ionization detector (FID) and Fourier transform–ion cyclotron resonance–mass spectrometer (FT-ICR MS) to understand the presence of different types of compounds. The identified compounds in the liquids were classified as benzene derivatives, naphthalene derivatives, polycyclic aromatic hydrocarbons, saturated and unsaturated hydrocarbons and sulfur-containing compounds. The presence of lighter hydrocarbon fractions in HFO acts as a hydrogen donor and resulted in the formation of more saturated hydrocarbons compared to VRO under pyrolysis conditions. Compounds present in the heavy fraction (with high molecular weight) which could not be analyzed and identified in liquid samples using GC-MS/FID were analyzed using FT-ICR MS. Elemental analyses of solid residues obtained from pyrolysis were also performed. Twenty lighter hydrocarbons ranging from C1-C5 were identified and quantified in the pyrolysis vapors of both fuels.