Failure investigation on rear water wall tube of boiler

The dynamic creep rupture of a secondary superheater tube in a 43MW coal-fired boiler by the decarburization and multilayer oxide scale buildup on both sides

“…There are various root causes resulting in the tube overheating, including a hotspot due to the localized uneven flue gas distribution [8,12], the tube scale buildup [1,4,8,9], and the steam flow reduction due to the scale exfoliation [10,21]. As the reference sample was cut from the same burst tube, the same steam flowed through from the reference location to the burst location.…”

“…The original microstructures were ferrite and pearlite. Above 600 ºC [2,12], pearlite decomposes and forms the spheroidized carbides. Minor hardness reduction occurs with spheroidization.…”

“…Such as the steam-side oxide scales [1,9], the sodium aluminium silicate scale [4], the scale exfoliation [10,21], localized uneven flue gas distribution [8,12], and the clinker formation [8]. However, in all of previous studies, the continuing decarburization at high temperatures has not been taken account in boiler tube creep failure analyses.…”

“…The classic methodology applied the Larson-Miller Parameter (LMP) to analysis the tube life [5][6][7][8]. In recent studies, researches focused on the aspects of metallurgical and oxide scales [9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Study on influence of three kinds of stress on crack propagation in butt welds of spiral coil waterwall for ultra supercritical boiler

“…The manufacturing workload is large and the production process is complicated [1]. The spiral coil waterwall is the key functional component of ultra supercritical boiler for variable pressure operation.…”