Effect of flue gas constituents on boiler tube failure of a captive power plant

Abstract

Water leakage was reported from one of the superheater tubes of boiler during operation. The power plant is a part of copper ore smelting and refining industry. It was observed, that the leakage took place through cracked region of the tube, which was severely damaged due to chemical attack. Damage occurred due to reaction between flue gas and outer wall of super heater tube. Inefficient treatment of flue gas resulted in retention of metal particles, SO2 gas and particulate within the same in substantial concentration. When the same flue gas was used in boiler, SO2 reacted with tube surface at elevated temperature. The incident lead to wall thinning and deep pit formation over tube surface. Metal particles was fused, adhered to tube surface and triggered secondary cracking during operation. Gradual wall thinning, increment in pit size and crack propagation through thickness resulted in ultimate failure of tube material.