A Monte Carlo solution for the combustion hot spot analysis in a floor-fired box furnace

The combustion zone in a process heater can be treated as an agglomeration or series of confined jet-flame systems that emanate from burner tiles and expand to an allocated fire box cross-sectional area. Possible failure of the tubes containing the process fluid because of local overheating requires the ability to predict detailed radiative heat flux and temperature distribution from the knowledge of the inlet and boundary condition and the system geometry. A Monte Carlo model along with a direct integral method has been developed which is capable of determining the heat transferred by radiation. The variation of the dimensionless heat flux number with varying firebox to burner area ratio, length to clearance ratio, a dimensionless distance along the combustion zone, and the number of packets reaching the tube is studied. C programs are written to generate the random numbers and to use them in the Monte Carlo simulation of the single-side-gas-fired tubes in floor-fired box furnace. Results are displayed for the variation of heat flux along the length of the vertical tube carrying the process fluid for single side fired tubes in a two-burner floor-fired box. The results of the probabilistic model are in good agreement with the published data. The present model serves as an engineering model that can predict the radiative heat transfer process in a process burner with moderate computational resources in a relatively short time. The present model, therefore, will be beneficial to practicing engineers for conducting radiative heat transfer calculations.