Prediction of Remaining Life of the Steel Shell of a Blast Furnace

Abstract

Thermal fatigue life evaluation is conducted for the steel shell of a blast furnace where hot spots have occurred repeatedly. Thermal elasto-plastic FEM analysis is used and, as a method of thermal fatigue life evaluation, the strain-range partitioning creep-fatigue analysis is adopted. It is proved to be possible to predict the remaining life of the steel shell successfully based on the following results:
(1) It is the center of a hot spot on the inner surface of the steel shell that undergoes the largest cyclic deformation during a cycle of a hot spot.
(2) Thermal fatigue damages, which are accumulated by repetition of hot spots, consist of those resulted from both the plastic strain range and the ratchetting strain.
(3) A higher hot-spot temperature, a thicker steel shell and a larger hot-spot diameter reduce thermal fatigue life of the steel shell.
(4) Total value of thermal fatigue damages at the notched part of the steel shell can be detected by measuring the increase in shell thickness of its smooth part independent of a hot-spot temperature.