Abstract
In previous work, the authors developed a procedure for assessing the remaining life of reformer furnace tubes based the results of a multi-parameter inspection technique. The current paper discusses how that procedure can be applied to optimize the remaining useful life of centrifugally cast reformer tubes, primarily those made of the Nb-modified and micro-alloyed HP materials. It can be applied to evaluate the benefits of controlling important operating parameters, including tube temperature, heat flux, startup/shutdown frequency, and operating trip frequency. The effects of material selection, tube wall thickness, and internal pressure can be evaluated. The procedure also can be employed to demonstrate which parameters or combinations of parameters are important to measure during tube inspection. These include creep strain at the tube interior and exterior, tube wall thinning, early stages of creep damage as evidenced by void formation and growth, later stages of creep damage as evidenced by the formation of fissures (linked voids) and microcracks, and cracking at the tube interior or exterior surface. Single-parameter inspection techniques, such as measurement of tube diameter, have a low effectiveness. Multi-parameter inspection techniques are required for high effectiveness.
