Combustion characteristics of rice-husk in a short-combustion-chamber fluidized-bed combustor (SFBC)

A short-combustion-chamber fluidized-bed combustor (SFBC), of 250 kWth capacity, was developed and tested for combustion characteristics of rice-husk, i.e. combustion efficiency (Ec), heat rate intensity (Ic), temperature distribution, and gaseous pollutant emissions. The effects of fluidizing velocity, excess air, and combustor loading were analyzed. The results indicated that the system could operate without any secondary solid as bed material, and could achieve high combustion efficiency and high heat rate intensity. Solid recirculation within the bed, created by a solid recirculating ring and an air vortex, played an important role in efficient combustion, even in a relatively short-combustion-chamber. A maximum Ec of 99.8% and a maximum Ic of 1.54 MWth m−2 were realized. Increasing fluidizing velocity and excess air caused decreases in Ec. CO and NOx emissions increased with increased excess air, and were in the range 50–550 ppm and 230–350 ppm, respectively.