Assessing the Condition and Estimating the Remaining Lives of Pressure Components in a Methanol Plant Reformer: Part 2 — Engineering Evaluation

Statoil Tjelbergodden operates a 2,400 ton/day methanol plant in Norway. Part 1 of this paper described the advanced non-destructive examination (NDE) technologies that were applied to obtain data for engineering evaluation of radiant catalyst tubes, outlet pigtails, and outlet collection headers. The inspection results were compiled along with data on materials properties and plant operating conditions for use in a series of life prediction studies. This paper describes the assessment methodologies that were applied in evaluating the remaining life of the in-service components. The special purpose WinTUBE™ finite element software was applied to predict remaining catalyst tube creep life based on the computed creep stress-strain response and creep damage accumulation under simulated future operating conditions. Outlet headers and pigtails were modeled using general purpose finite element software to compute stresses and strains during operation. Following the methodology of API 579-1/ASME FFS-1 the computed stresses and strains were used to predict remaining creep life. Using the remaining life estimates to decrease the potential of in-service failures and increase the reliability of future reformer operations is discussed.