Numerical and experimental study on flameless oxy-fuel combustion in a pilot- scale and a real-size industrial furnace

Highlights: • Proper CFD model is introduced for simulating Flameless oxy-fuel combustion. • Experiments were done in pilot-scale and real-size furnaces for verification. • Suction pyrometer and S-type thermocouples were used for temperature measurements. • Comparisons of the predicted and measured results, show acceptable deviations. Previously validated CFD model was used to simulate the flameless oxy-fuel combustion in a pilot-scale furnace and a full-scale soaking pit furnace. The CFD predictions for temperature were compared with experimental data measured by shielded S-type thermocouples for both furnaces. The results indicate the validity of using shielded S-type thermocouples for temperature measurement, although use of the suction pyrometers renders more accurate results. Afterwards, the validation of previously proposed CFD model for simulating the flamaless oxy-fuel combustion is investigated in a full-scale soaking pit furnace in the production route of steel bars. The validation has been done by comparing the predicted temperatures with experimental data obtained by using S-type thermocouples. For both pilot-scale and full-scale furnaces a three dimensional CFD model with realizable k-ε, Probability Density Function (PDF) with Steady Laminar Flamelet Model (SLFM) and Discrete Ordinates Model (DOM) with Sum of The Weighted Gray Gases Model (SGGWM) for simulating turbulence, combustion and radiation was performed. The predicted temperature results show a good agreement with measured data from shielded S-type thermocouples for pilot-scale and full-scale furnace. More specifically the maximum deviation was 3.3% and 9.95% respectively. Afterwards, the simulation results on the full-scale furnace have been used to investigate the non-uniformity of temperature distribution inside the chamber.