## 1 Introduction  
SMR (steam methane reforming) is frequently adopted for producing hydrogen in the petrochemical industry. The combustion reaction activated by the burners provides heat to the catalyst tubes in which the reforming reaction occurs, and the liquid petroleum gas or the natural gas is converted into hydrogen. For reformer design, a classical optimization task is the control of catalyst tube temperature because the catalysts inside the tube should have high activity while the tube should have minimal damage and acceptable lifetime. In the past few decades, there has been a lot of research conducted on the analysis of the catalyst tube damage and lifetime. [PERSON] et al. [1] analyzed the lifetimes of fired heater tubes. The authors statistically characterized the uncertainty associated with the omega creep procedure of the API-579 Part 10 by treating the primary input parameters as random variables and processes. They also employed Monte Carlo simulations to estimate the probability of tubes failing for a specified time. [PERSON] [2] determined the cause of damage by investigating a reformer catalyst tube using diffraction, light microscopy, transmission electron microscopy, etc. [PERSON], [PERSON], and [PERSON] [3] discussed the progress in increasing the catalyst tube lifetime and the reasons accounting for the withdrawal of catalyst tubes from service. [PERSON] and [PERSON] [4] addressed the microstructure evolutions and mechanical property variations of catalyst tubes after long-term service. The authors indicated that the content of the interdendritic carbide could be used to predict the tube lifetime. [PERSON] et al. [5] used tensile testing, stress rupture testing, and microstructural analysis to predict the remnant life of a catalyst tube of eleven years of service. [PERSON] et al. [6] analyzed the damage characterization of two catalyst tubes of nearly 10 years of service. They employed scanning electron microscopy, light optical microscopy, and mechanical testing to inspect creep, aging, carburization, precipitation, cavitation, phase transformation, and incipient micro-cracking. The authors indicated that differences in process conditions, as well as type and frequency of cleaning maintenance for decoking, may lead to different damage mechanisms of degradation on catalyst tubes. [PERSON] et al. [7] analyzed the reformer catalyst tubes failed after eight years of service. They assessed the tube lifetime by Larson-Miller parameter method. The authors concluded that the failure was caused by the local overheat leading to premature creep failure. [PERSON], [PERSON], and [PERSON] [8] analyzed the remaining life for reformer tubes of a methanol plant. They evaluated the tube lifetimes from their outside diameters, inside diameters, and the middle of the tube thicknesses. [PERSON] et al. [9] investigated the remaining life for the catalyst tubes of a fertilizer plant. The investigation included microscopy, hardness measurement, dimensional measurement, hot tensile tests, and accelerated creep tests. The authors concluded that overheating is the primary cause of the significant degradation in microstructures and mechanical properties of the catalyst tube. [PERSON], [PERSON], and [PERSON] [10] metallographically analyzed the damage states of a catalyst tube of ten years of service. They found that the catalyst tube is damaged more seriously in the lower portion. [PERSON], [PERSON], and [PERSON] [11] discussed the damage mechanisms of catalyst tubes and the assessment methods of damage extent and remaining life. They applied a simplified method to evaluate the damage extent. A radiographic procedure for evaluating creep damage is also described. The rapid developments in computer technology, physical models, and numerical methods enable the broad application of CFD to analyze systems involving fluid flow and chemical reactions. Further, problems that cannot be investigated experimentally can also be analyzed using CFD. Some recent studies of SMR by CFD are reviewed below.