A new technique for the measurement of theproduct CO/CO2 ratio at the surface of charparticles burning in a fluidized bed

摘要

A new experimental technique is proposed to measure the product CO/CO2 ratio at the surface of sphericalchar particles during fluidized bed combustion. It is based on the measurement of the burning rate of asingle char particle under low oxygen concentration conditions and on the use of an accurate prediction ofthe particle Sherwood number. This technique was applied to spherical char particles obtained from a bituminouscoal which is characterized by a low attrition and fragmentation propensity. The product CO/CO2ratio was measured at a bed temperature of 850 °C and at a fluidization velocity of 0.3 m/s in a lab-scaleapparatus operated with a bed of 0.5–0.6 mm sand. The char particle size was varied between 2 and 7 mmand the inlet oxygen concentration between 0.1% and 2.0%. Results showed that under the experimentalconditions investigated carbon was mostly oxidized to CO2 within the particle boundary layer, with amaximum fraction of carbon escaping as CO of 10–20% at the lowest oxygen concentrations and largestparticle sizes.