Stress Analysis of Steam-Methane Reformer Tubes

A steam-methane reformer (SMR) tube is very important in oil refinery industry. An SMR tube is a device used in steam reforming or auto thermal reforming, and it is a type of chemical synthesis which can produce pure hydrogen gas from natural gas using a catalyst. The tube is expected to last 100,000 hours or 11.4 years but in many instances some of these tubes fail prematurely. Since the material cost is a large investment, thorough analyses are necessary to predict possible failure of the steam reformer tube in order to save operation and downtime cost. In order to reliably predict the performance of the tube, good assessment of the stresses acting at any point along the tube length and thickness is needed. In this project, Finite Element Method (FEM) was used to perform the stress analysis of the tube and the analysis considered the disparity in stresses along the tube length and thickness due to temperature and pressure differences. ANSYS software was used in performing the analysis. Both 2D axisymmetric and 3Dapproach were used in the analyses. The 2D axisymmetric models represent a slice of the actual 3D model that, if revolved around the y-axis of the reference Cartesian coordinate system, would become the original 3D structure. The advantage of using a 2D axisymmetric model compared to a 3D model is the reduced in calculation time and it is easier to change details to the geometry. Two types of analyses were performed, stress analysis due to internal pressure and stress analysis due to difference in temperature along the tube. In the first analysis, the von Mises stress was highest at the inner wall of the tube and lowest at the center of the tube wall. For the second analysis, it was shown that the von Mises stress decreased from inner wall to minimum near the center of the tube wall and then increased to the outer tube wall.