Hydrodynamic and combustion behavior of low grade coals in the riser of a circulating fluidized bed combustor

Abstract

This study is conducted for understanding the fluidization behavior in a CFB combustor for low ranked coals. A lab-scale cold CFB test rig was built at the NFCIET Multan for understanding the fluidization behaviour. Influence of fluidizing air on the fluidization behavior was observed. It was found that voidage along the riser height is affected by riser geometry. The combustion behavior of low grade coals from Thar coal was also explored in a CFB Combustor. The influence of the fluidizing air on the combustion erformance was examined and their effect on emissions was established. The temperature in the riser of the CFB rose quickly to around 900°C. This rise in temperature has caused an increase in the amount of exhaust gasses which has their influence on the suspension density. From this study, a firsthand experience of combustion behavior of low grade Pakistani coals was documented.

Keywords

• circulating fluidized bed (CFB)
• combustion
• fluidization
• hydrodynamics
• low grade coal