Analysis on Corrosion Causes of Induced Draft Fan Blade in Circulating Fluidized Bed Boiler With Mixed Burning Solid Waste Fuel

Abstract

In order to study the reasons for serious corrosion problem of induced draft fan blades of a 2×300 MW circulating fluidized bed unit which were blended burning solid waste fuel, the samples of the corroded blade and ash from different positions were taken. The analysis results of X-Ray diffractomer (XRD), scanning electron microscope (SEM) and X-ray fluorescence (XRF) show that Cl element is found in the rust samples and on the surface of the blades, and no trace of S element is found. Therefore, it is determined that the cause of the corrosion of the blades is Cl corrosion. Through the test of ash samples at different positions of the boiler, it is found that the ash hardened on the air preheater and the ash collected by bag filter behind the semi-dry flue gas desulfurization are enriched in Cl, which is the key to cause the Cl corrosion of the equipment. The blended burning solid waste fuel and sludge are the main sources of Cl. The enrichment of Cl in the ash hardened on the air preheater is found related to NH3 escaped from selective non-catalytic reduction, the reason of Cl enrichment in desulfurized ash needs further study.

Keywords

• circulating fluidized bed
• boiler
• solid waste fuel
• blade corrosion
• cl corrosion