Influence of O2/CO2 mixtures on the fluid-dynamics of an oxy-fired fluidized bed reactor

This paper addresses the mathematical development and the experimental validation of a semi-empirical model designed to characterize the fluid-dynamic response of a fluidized bed reactor under oxy-fuel operation. The objective is to survey the main differences between a conventional air operation and a novel O2/CO2 operation, as for the interactions of solid-phase and gas-phase. The model provides all the relevant variables describing the fluid-dynamics, and it is conceived to simulate the performance of a lab-scale facility. Data gathered from the cold- and hot-operation of a 90 kWth oxy-fired fluidized bed are used for validation purposes. Bed porosity, minimum fluidization velocity and bubbles’ size are detected to change under oxy-firing conditions. Once validated, the tool will be used to predict the performance under new fluidizing atmospheres and will be integrated within an entire model coupling fluid-dynamics, combustion and heat transfer phenomena.

► A mathematical model provides all the relevant fluid-dynamics variables. ► Data from cold- and hot-operation of a 90 kWth oxy-FB are used for validation. ► Bed porosity and minimum fluidization velocity change under oxy-firing conditions. ► The larger CO2 concentration in the fluidizing gas, the greater bubbles fraction.