The influence of transport phenomena on the fluidized bed combustion of a single carbon particle

The burning rate and temperature of the carbon particles are known to affect the efficiency of a fluidized bed combustor, and also the emission levels of undesired noxious components. The main results of an extensive study on the fluidized bed combustion behaviour of a single carbon particle [1] are summarized. Calculations have been carried out with a newly developed transient model, the ASPC model, and also with the much simpler progressive conversion model. Besides, many experiments have been performed in a lab-scale fluid bed construction to measure the burning rate and temperature of individual carbon particles for various conditions. From the comparison between experimental results and model predictions it has been overall concluded that the ASPC model is especially useful in i) describing the complex behaviour of progressive carbon conversion for the regime of combustion controlled by carbon reactivity plus intraparticle oxygen diffusion, and ii) estimating the conditions for which transition to the regime of external mass and heat transfer control occurs. Accurate prediction of the carbon particle burning rate and temperature is only possible for the latter combustion regime.