The effects of oxygen and gas composition on the flammability limits of steelworks gas blends under oxygen-enriched condition

In this paper, the flammability limits of steelworks gas blends under different oxygen concentrations were measured using a self-designed experimental operation platform. The measurement indicates that the lower flammability limit increased slightly and the upper flammability limit increased significantly with the increase of oxygen. The reasons are mainly from the thermodynamics and chemical characteristics of O2. A prediction model for calculating the flammability limits of complex gas mixtures was developed using the limiting laminar flame speed method. In the oxygen-enriched environment, the influence of single component gas on the flammability limits of gas mixtures was calculated using the prediction model. The combustible species of the gas blends are CH4, H2 and CO. The upper and lower flammability limits are reduced by the CH4 concentration increase, while the upper flammability limit increased and the lower flammability limit decreased as H2 and CO concentrations increase. The non-combustible gas components are N2 and CO2. Increasing the concentrations of these two inert gases decreases the upper flammability limits and increases the lower flammability limits of the gas mixture, and the effect of CO2 on the flammability limits of the gas mixture is more notable than that of N2, since CO2 and N2 have different thermodynamic and chemical properties.