Cracking Reasons Analysis of Superheater Tubes of a Waste to Energy Power Plant
The reasons for a large number of cracks in the superheater tubes of a waste to energy power plant were analyzed,and the cracked steel tube samples were studied and analyzed by physical and chemical detection methods such as macro inspection,chemical composition analysis,hardness detection,microstructure and fracture observation,and energy spectrum analysis.The results show that the elbow of the serpentine tube has poor ovality quality and the structure of the superheater header joint is improper,all of which have higher residual stress.The crack originated from the inner wall of the pipe and expanded outward,showing obvious intergranular fracture characteristics.There is Na and P elements remaining on the fracture surface.In summary,the main reason for the cracking of the superheater pipe is the improper operation of the alkali cleaning during the boiler commissioning,which causes the alkaline liquid to flow into the superheater pipe.The alkaline liquid concentrates at the welds and elbows,with the high temperature and superimposed stress,the superheater tubes cracked because of alkali stress corrosion finally.
waste to energy power plantsuperheater tubesalkali stress corrosion
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