Combustion and flame characteristics of CL-ODH byproduct fuel mixture with high CO2 dilution

This study investigates combustion performance of a CO2 rich fuel mixture containing ethane and methane as active species using a constant volume combustion chamber. This fuel is obtained as a byproduct of a chemical looping based oxidative dehydrogenation (Cl-ODH) process ethylene production. The byproduct gas mixture has a CO2 concentration of 40.79%, 39.49% ethane, and 4.88% methane by weight with other minor compounds. Using the fuel for energy extraction would improve the process efficiency of the ethane to ethylene conversion. After initial combustion modelling, the gas fuel mixture was reduced to just the major species: CO2, ethane, and methane. The mixture was then tested for flammability limits and combustion performance under spark-ignition conditions. Effects of ambient conditions like temperatures between 300 to 400 K with initial pressures from 1 to 10 bar were tested. The effects of stoichiometry were tested to understand flame velocities and heat release. The fuel mixture showed an overall reduced flame velocity compared to gasoline. Instability in combustion was believed to be caused by the dissociation of ethane under elevated conditions. At higher pressures, the flame produces lower cumulative heat release. Data from this study was used to modify a small-scale spark-ignition engine to use this fuel and produce usable energy.