Effect of pressure and carbon dioxide concentration on heat transfer at high temperature in a Pressurized Circulating Fluidized Bed (PCFB) combustor

Experiments are performed in an electrically heated 52.5 mm diameter and 2020 mm high pressurized circulating fluidized bed to investigate the bed-to-wall heat transfer in it. The bed-to-wall heat transfer is determined from the radial temperature distribution in the wall. The CO2 content of the fluidizing gas is changed by either adding varying amounts of CO2 to the air or by burning coal and coke with and without an addition of limestone. The heat transfer coefficient increases with both system pressure and bed temperature due to increased contribution of gas convection and radiation. The heat transfer coefficient also increases with CO2 concentration due to increased non-luminous radiation from CO2.