Numerical investigation of oil shale combustion characteristics in a high-low differential velocity CFB boiler using the CPFD model

This study employs the computational particle fluid dynamic model to simulate a 65 t/h oil shale-fired high-low differential velocity circulating fluidized bed (CFB) boiler. The effects of the excess air ratio on furnace temperature, gas composition, particle residence time, and pollutant emissions were analyzed. Results show that an excess air ratio of 1.10 intensifies particle back-mixing, enhancing combustion while reducing NO and SO2 emissions. The optimal condition combines this ratio with a 1.5:1 main/side bed air distribution, achieving the lowest emissions. This work provides valuable insights for optimizing CFB boiler operation.