{"references": ["Akers, W. W., Camp, D.P., \"Kinetics of the Methane-Steam Reaction\",\nAIChE. J. 4 (1955) 471-474.", "Beek, J., \"Advances in Chemical Engineering\", Vol. 3, Academic Press,\nNew York (1962).", "Borkink, J. G. H., Westerterp, K. R., \"Influence of Tube and Particle\nDiameter on Heat Transfer in Packed Beds\", AIChE. J. 38 (1992) 703-\n715.", "Daubert, T.E., Danner, R.P., Design Institute for Physical Property Data,\nAmerican Institute of Chemical Engineers, Hemispher Publishing\n(1991).", "De Deken, J. C., Devos, E. F., Froment, G. F., \"Steam Reforming of\nNatural Gas: Intrinsic Kinetics, Diffusional Influences, and Reactor\nDesign\", Chemical Reaction Engineering, ACS Symp. Ser., 196, Boston\n(1982).", "Derkx, O. R., Dixon, A. G.,\" Determination of the Fixed Bed Wall Heat\nTransfer Coefficient using Computational Fluid Dynamics\", Numer.\nHeat Transfer, Part A, 29 (1996) 777-785.", "Design and Construction of a Methanol Pilot Plant Based on Reforming\nTechnology, National Iranian Petrochemical Company (NIPC) Project\nNO. 81118018, Iran (2005).", "Dixon, A.G., Nijemeisland, M., Stitt., E.H, \"CFD Study of Heat Transfer\nnear and at the Wall of a Fixed Bed Reactor Tube: Effect of Wall\nConduction\", Ind. Eng. Chem. Res. 44 (2005).", "Elnashaie, S. S. E. H., Soliman, M.A., Al-Ubaid, A.S., Adris, A., \"On\nthe Non-monotonic Behavior of Methane-Steam Reforming Kinetics\",\nChem. Eng. Sci., 45 (1990) 491-501.\n[10] Ergun, S., \"Fluid Flow through Packed Beds\" Chem. Eng. Prog. 48\n(1952) 89-94.\n[11] Farhadi, F., Motamed Hashemi, M.M.Y., Bahrami Babaheidari, M.,\n\"Modeling and Simulation of Syngas Unit in Large Scale Direct\nReduction Plant\", Ironmaking and Steelmaking, 30 (2003) 35-41.\n[12] Filla, M., \"An Improved Roesler-type Flux Method for Radiative Heat\nTransfer in One-dimensional Furnaces\", Chem. Eng. Sci. 39 (1984) 159-\n161.\n[13] Froment, G. F., Bischoff, K. B., Chemical Reactor Analysis and Design,\nWiley, New York (1990).\n[14] Golebiowski, A., Wasala, T., \"Thermal Processes in Catalytic\nReforming of Methane with Water Vapor\", International Chem. Eng.,\n13 (1973) 133-139.\n[15] Gunn, D. J., \"Axial and Radial Dispersion in Fixed Beds\", Chem. Eng.\nSci. 42 (1987) 363-373.\n[16] Hyman, M.H., \"Simulate Methane Reformer Reactions\", Hydrocarbon.\nProcess. , 49 (1968) 131-137.\n[17] Kvamsdal, H. M., Svendsen, H. F., Olsvik, O., \"Dynamic simulation and\nOptimization of a Catalytic Steam Reformer\", Chem. Eng. Sci. 54\n(1999) 2697-2706.\n[18] Li, C., Finlayson, A., \"Heat Transfer in Packed Beds-A Reevaluation\",\nChem. Eng. Sci. 32 (1977) 1055-1066.\n[19] Logtenberg, S. A., Dixon, A. G., \"Computational Fluid Dynamics\nStudies of the Effects of Temperature-Dependent Physical Properties on\nFixed-Bed Heat Transfer\", Ind. Eng. Chem. Res., 37 (1998) 739-747.\n[20] Murty, V.S., Murthy, M.V.K., \"Modeling and simulation of a top-fired\nreformer\",Ind. Eng. Chem. Res 27 (1988) 1832-1840.\n[21] Pedenera, M. N., Pina, J., Borio, D.O., Bucala, V., \"Use of a\nHeterogeneous Two-dimensional Model to Improve the Primary Steam\nReformer Performance\", Chem. Eng. J. 94 (2003) 29-40.\n[22] Rajesh, J.K., Gupta, S.K., Ray, A.K., \"Multiobjective optimization of\nsteam reformer performance using genetic algorithm\", Ind. Eng. Chem.\nRes. 39 (2000) 706-717.\n[23] Ravi, K., Joshi, Y. K., Guha, B. K., \"Simulation of Primary and\nSecondary Reformers for Improved Energy Performance of an\nAmmonia Plant\", Chem. Eng. Technol. 12 (1989) 358-364.\n[24] Roesler, F.C., \"Theory of radiative heat transfer in co-current tube\nfurnaces\", Chem. Eng. Sci. 22 (1967) 1325-1336.\n[25] Rostrup-Nielsen, J. R., Catalysis. Sci. Technology, Vol IV, Springer,\nBerlin (1984).\n[26] Sadri, M., Vakhshouri, K., Motamed Hashemi, M. M. Y, \"Coke\nFormation Possibility during the Production of Reducing Gas in Large\nScale Direct Reduction Plant\", Ironmaking and Steelmaking, 34 (2007) .\n[27] Singh, C. P. P., Saraf, D. N., \"Simulation of side-fired hydrocarbon\nreformers\", Ind. Eng. Chem. Process. Des. Dev 18 (1979) 1-7.\n[28] Tallmadge, J. A., \"Packed Bed Pressure Drop-An Extension to Higher\nReynolds Numbers\", AIChE. J. 19 (1970) 1092-1093.\n[29] Dixon, A. G., \"Wall and Particle -Shape Effects on Heat Transfer In\nPacked Beds Transfer in Fixed Beds at Very Low Tube-to-Particle\nDiameter Ratio\", Chem. Eng. Communication, 71 (1988) 217-237.\n[30] Dixon, A. G., \"Heat Transfer in Fixed Beds at Very Low Tube-to-\nParticle Diameter Ratio\", Ind. Eng. Chem. Res. 36 (1997) 3053-3064."]}

A rigorous two-dimensional model is developed for simulating the operation of a less-investigated type steam reformer having a considerably lower operating Reynolds number, higher tube diameter, and non-availability of extra steam in the feed compared with conventional steam reformers. Simulation results show that reasonable predictions can only be achieved when certain correlations for wall to fluid heat transfer equations are applied. Due to severe operating conditions, in all cases, strong radial temperature gradients inside the reformer tubes have been found. Furthermore, the results show how a certain catalyst loading profile will affect the operation of the reformer.