prediction of flame envelope of hydrocarbon fuels in industrial fired heaters

Prediction of flame envelope in industrial scale fired heaters/boilers is a critical objective to prevent flame merging or flame impingement on process tubes. in design of industrial fired heaters/boilers, well prediction of flame envelope from any kind of conventional or low-nox burners with low computational cost is very much interested. however, exact simulations which relay on detailed chemical mechanisms for tracking hydroxyl radical as flame marker are computationally expensive. some other affordable techniques based on prediction of carbon monoxide iso-surface are available in the literature. however, no systematic study has yet been performed to compare various recommended criteria. in present study, three recommended criteria of co iso-surface for determination of flame envelope have been investigated numerically and validated with industrial data as well as with a standard numerical simulation coupled with detailed chemical kinetics mechanism. it is found that the api 535 recommendation (co iso-surface = 2000 ppmvd) is a conservative and reliable criterion while the uop criterion is kind of stringent.