The flammability limits of H2–CO–CH4 mixtures in air at elevated temperatures

The present contribution reports experimentally obtained values of the flammability limits of some fuel mixtures made up of H2, CO, and CH4 in air at different initial mixture temperatures of up to 300 °C. The potential catalytic effects of the surface of the test apparatus when the fuel–air mixtures were allowed to reside within the test apparatus at elevated temperatures for different time periods prior to ignition were also considered. Both stainless steel and quartz flame tubes of identical design and size were employed in the investigation. It was found that at relatively low initial temperatures the experimentally obtained limit values of fuel mixtures containing relatively low concentration of hydrogen, followed closely the corresponding values calculated according to the well-known Le Chatelier's Rule. However, for higher concentrations of hydrogen in the fuel mixtures and/or for temperatures higher than 200 °C, significant deviations could be observed for values of the rich limits, even for short residence times prior to ignition.