Numerical analysis for nitrogen dilution on flammability limits of hydrocarbon mixtures

There are numerous flammability literature data available for pure substances. For fuel mixtures, however, these are not always available. Especially, for fuel mixture storage, operation, and transportation, inert gas inerting and blanketing have been widely applied in chemical process industries while the related data are even more scarce. Lower and upper flammability limits of hydrocarbon mixtures in air with additional nitrogen were measured in this research. Typically, fuel mixture lower flammability limits almost keep constant at different fractions of added nitrogen; and approximately upper flammability limits of fuel mixture vary linearly with the addition of nitrogen except those mixtures containing ethylene. Numerical analysis of effect from inert gas dilution on fuel mixture lower and upper flammability limits was conducted by introducing the parameter of inert gas dilution coefficient, through which fuel mixture flammability properties, e.g., lower flammability limit, upper flammability limit, and minimum inerting concentration, can be quantitatively characterized with the modified Le Chatelier's mixing rule.