Optimization analysis of gasification performance in Fushun-type retorting furnace based on CFD simulation and orthogonal experiments

• Plant-calibrated 3D CFD model predicts in-furnace temperatures within 8.4% (7.5% avg). • CFD with L 27 orthogonal design and ANOVA quantifies factor effects and interactions. • Increasing λ from 0.192 to 0.288 raises outlet temperature by ≈300 K and gasification efficiency by 10–15 percentage points. • Optimal window (λ = 0.24–0.28, 75–80°C air, ≥90 % steam) yields >80 % carbon conversion with near-max HHV. To improve gasification performance in Fushun-type retorting furnaces, a three-dimensional CFD model of the gasification section was developed using the Realizable k–ε turbulence model, a porous-medium description of the semicoke bed, and user-defined gas–solid reaction kinetics. Under a representative industrial condition (primary air temperature 80 °C, excess air ratio λ = 0.240, steam saturation 100 %), predicted temperatures at three elevations agree with thermocouple data with a maximum relative error of 8.4 %, confirming sufficient accuracy for engineering analysis. An L 27 orthogonal design with ANOVA was used to study the effects of λ (0.192–0.312), primary air temperature (65–90 °C) and steam saturation (75–100 %) on outlet syngas temperature, sensible enthalpy, higher heating value (HHV) and gasification efficiency. Increasing λ from 0.192 to 0.288 raises outlet temperature by about 300 K and gasification efficiency by 10–15 percentage points, while HHV peaks near λ ≈ 0.26 and then declines due to over-oxidation. Moderate air preheating from 65 to 80 °C increases sensible enthalpy by 40–60 kW, whereas further heating to 90 °C reduces HHV by 5–10 %. Raising steam saturation from 75 % to 100 % improves gasification efficiency by over 10 percentage points with a small temperature penalty. Range and ANOVA analyses consistently identify λ as the dominant factor; primary air temperature mainly governs HHV, with steam saturation providing secondary regulation. The CFD–orthogonal framework recommends an operating window of λ ≈ 0.24–0.28, primary air temperature 75–80 °C and steam saturation ≥ 90 %, yielding near-maximum HHV and gasification efficiency above 80 %.