Influence of TiO2Additive on Vaporization of Potassium during Straw Combustion

In this work, the influence of TiO 2 on the vaporization of K during combustion of straw under fixed bed condition was investigated experimentally. Controlled combustion experiments with a varied amount of TiO 2 in straw pellets were performed in an 8 kW pellet burner together with sampling of particles (impactor and absolute filter), analysis of the flue gas composition (Fourier transform infrared, FTIR), and chemical analyses of the collected particles and bottom ash (inductively coupled plasma-atomic emission spectroscopy (ICP-AES), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD)). The experimental results showed that the vaporization of K from the fuel bed was significantly reduced when TiO 2 was used as an additive. The vaporization of K was reduced by ∼40−50% for an optimal amount of TiO 2 additive. The optimal added TiO 2 for the straw used in this work corresponds to a Ti/K (wt) ratio between ∼0.6−1.0. If more TiO 2 was added to the fuel, the release of K to the gas phase was not further reduced and unreacted TiO 2 was found in the bottom ash.