Deposition occurred on surface of air nozzles in a biomass-fired circulating fluidized bed(CFB)boiler.Several measurement methods were applied to identify the compositions.Visual inspection shows the deposition has a typical layered structure.Detailed study was carried out by analyzing the sample via SEM(Scanning Electron Microscope)

EDS(Energy Dispersive Spectrometer)and XRD(X-Ray Diffraction).It founds each layer of the deposition has similar elemental composition and K

Na

Cl are the main elements constituting the deposition.From the viewpoint of chemical compounds

alkali metal salts like KCl and NaCl are the main components.Condensation of alkali metal salts in gas phase on nozzle surface was considered to be the major way by which the initial deposit formed

while the local high temperature was an important factor in the development of the deposit.Therefore

decreasing the heavy impurities from fuel and keeping high quality fluidization are effective to control the deposition formation on air nozzles.