An Annular Combustor Natural Gas Ignition Model Derived From Atmospheric Sector Experiments

Results from ignition and cross-ignition tests performed on an atmospheric 60°-sector test rig equipped with three EV-type burners are presented. Based on these results a model was developed for an annular combustor, which calculates the primary ignition and burner-burner cross-ignition limits for the combustor in terms of burner operation variables (equivalence ratio and pilot fuel ratio) using a generally applicable methodology described in the paper. Key ingredients of the model are the description of mixture flammability and a mixing model representing the ignition relevant mixing behaviour of the burners in the annular combustor. Ignition and cross-ignition are observed to occur, if the mixture equivalence ratio determined from the mixing model is above the flammability limits calculated for the particular operating conditions. Even in the case of cross iginition across an externally piloted or switched-off burner, the model reproduces the experimental cross-ignition limits, confirming that the basic physics have been captured.