Cause Analysis of Economizer Tube Leakage in a Biomass Power Plant

Abstract

Aiming at the leakage of economizer tube in a biomass power plant, the leakage mechanism of economizer tube was studied by means of macro analysis, chemical composition analysis, metallographic structure, micro Vickers hardness test and scanning electron microscope. The results show that there is no misuse of materials or unqualified chemical composition in the leaked economizer tube; The metallographic microstructure is ferrite + pearlite, and the spheroidization level is between 2.0 and 2.5, indicating that there is no obvious spheroidization in the pipe section submitted for inspection; At the same time, the micro Vickers hardness value did not decrease significantly; The outer wall of the pipe is yellowish brown and there is delamination and peeling of attachments. A leakage hole can be seen in the middle of the pipe section, and there is obvious thinning at the edge of the hole, indicating that there is corrosion thinning. The chemical components of the corrosion products are mainly Fe and O, and contain a certain amount of Cl, s, P, Si, K, Ca and other alkali metal elements. Therefore, it can be inferred that the main cause of economizer pipe leakage is corrosion thinning.