INFLUENCE OF THE ADDITION OF HYDROGEN ON THE FLAMMABILITY INTERVALS OF THE METHANE, AIR AND CO2 MIXTURES

By adding H2 to CH4 the combustion characteristics improve considerably. The flammability characteristics of the CH4 are most well-known, but the CH4 enriched with H2 has a completely different behaviour regarding the flammability and the explosiveness. The understanding of the flammability of such mixture in the air is crucial to allow their safe use in industry. Lower and upper flammability limits are one of the most important parameters at the time of characterizing and handle flammable gases. This study is focused on the evaluation of the safety prevention measures more commonly apply to explosive atmospheres, specifically the inertization, by means of a nonflammable gas (CO2). This is defined through the limiting oxygen concentration (LOC), being the threshold value of inert gas concentration so that the propagation does not occur. The representation of the Flammability limits and the LOC in ternary diagrams allow separating the flammable mixtures and the non-flammable mixtures in two differentiate regions by means of a curve, named flammability interval. This interval is composed by the set of flammable mixtures of a ternary mixture. In previous studies, the flammability interval of the H2-CO2-air has been obtained, so this study intends to obtain the flammability interval of the CH4-CO2-air mixture in order to achieve the first step to define the flammability interval of the mixture CH4-CO2-H2-air.