Combustion behavior and pollutant emissions of batch fluidized bed combustion

• The combustion behavior in a vortexing FBC with a batch fuel feeding system is studied.
• Effects of particle sizes and feeding intervals on the pollutant emissions are also studied.
• Combustor temperatures and pollutant emissions change periodically with the feeding cycles.
• The highest temperature appears in the splashing or freeboard regions.
• There is an inverse dependency between the NOx and CO concentrations at the exit.

The combustion experiments were carried out in a pilot-scale vortexing fluidized-bed combustor (VFBC) with a batch fuel feeding system. Effects of particle sizes and feeding intervals on the temperatures within the combustor and the pollutant emissions at the exit of the combustor were studied. Rubber balls were used as the fuel to simulate the hazard waste. Silica sand was used as the bed material. The experimental results show that the combustor temperatures change periodically with the feeding cycles and the highest temperature appears in the splashing or freeboard regions. The mean bed and freeboard temperatures increase with the particle size, and decrease with the feeding interval. However, the mean bed and freeboard temperatures show a inverse trend. The mean CO concentration in the flue gas decreases with fuel particle size, but increases with feeding interval. There is an inverse dependency between the CO and NOx concentrations at the furnace exit. Results from this study would be helpful in developing more comprehensive physical model for VFBC with batch feeding system and setting optimal operational parameters in practical applications.