Effects of hydrogen blending on combustion and pollutant emission of propane/air in a model furnace with a rotary kiln burner

A rotary kiln burner is one of the critical equipment in various industrial processes, particularly in the field of material calcination. This study focuses on the effects of hydrogen blending in a rotary kiln burner operating with propane as a fuel. The primary objectives are to explore the effects of key parameters, such as hydrogen blending ratio, fuel hole size, and air flow rate, on the combustion and emission characteristics under the ignition condition. Results reveal that a hydrogen blending ratio of 10% leads to a 3.4% and 1.5% reduction in COx and NOx emission indexes, respectively. The hydrogen can be mixed with propane while maintaining the same total heat release, reducing carbon and nitrogen oxide emissions. Although adjusting the fuel hole size allows the flow characteristics after hydrogen blending to be restored to their pre-blending state, the combustion characteristics would be changed. With a 30% increase in air flow rate under fuel-rich ignition conditions, the propane consumption rate witnesses a 20.8% growth, accompanied by a parallel rise of 6.8% in both COx and NOx emission indexes. These numerical results can be a reference in designing kiln burners and selecting operating conditions.