Numerical modelling of a steam methane reformer

Abstract

Steam methane reformers are used in industry to convert methane (natural gas) and steam into hydrogen and carbon monoxide. The reformers consist of long pipes filled with catalyst pellets, heated by external burners. Previous researchers have conducted experiments to understand the behaviour of these reformers. Small scale experiments focussed on the reaction kinetics [Xu and Froment, AlChE 35:88--96, 1989). Industrial scale experiments found the effect of diffusional resistance on the reaction rate [Xu and Froment, AlChE 35:97--103, 1989]. From the experiments, a model was created to predict the behaviour of an industrial scale reactor. This model was solved numerically. The model incorporates heat, mass and momentum transfer to describe the temperature, composition and pressure along the reactor. A series of differential equations were solved in order to describe the reformer at each length segment. Within each segment another series of differential and algebraic equations must be solved to describe the diffusion and reaction behaviour inside the catalyst pores. The numerical model has been replicated in Python. It shows the behaviour of a reformer and the computation time is short enough to be useful in an industrial setting. An open source thermodynamics package was used to calculate various physical properties of the reacting gasses. SciPy mathematical algorithms and functions were used in this replicated model. After finishing the model, it will be regressed against data from a working reformer. Many parameters will be adjusted to ensure the model is an accurate representation. References

• G.F. Froment, K.B. Bischoff, and J. De Wilde. Chemical Reactor Analysis and Design, 3rd Edition. John Wiley and Sons, Incorporated, 2010. URL: https://books.google.co.nz/books?id=lbQbAAAAQBAJ.
• David G. Goodwin, Harry K. Moffat, and Raymond L. Speth. Cantera: An object-oriented software toolkit for chemical kinetics, thermodynamics, and transport processes. http://www.cantera.org, 2017. Version 2.3.0.
• R. E. Hicks. Pressure drop in packed beds of spheres. Industrial and Engineering Chemistry Fundamentals, 9(3):500–502, 1970. doi:10.1021/i160035a032.
• Liangfeng Lao, Andres Aguirre, Anh Tran, Zhe Wu, Helen Durand, and Panagiotis D. Christofides. Cfd modeling and control of a steam methane reforming reactor. Chemical Engineering Science, 148:78 – 92, 2016. doi:10.1016/j.ces.2016.03.038.
• Dean A. Latham, Kimberley B. McAuley, Brant A. Peppley, and Troy M. Raybold. Mathematical modeling of an industrial steam-methane reformer for on-line deployment. Fuel Processing Technology, 92(8):1574 – 1586, 2011. doi:10.1016/j.fuproc.2011.04.001.
• Jae Seong Lee, Juhyeong Seo, Ho Young Kim, Jin Taek Chung, and Sam S. Yoon. Effects of combustion parameters on reforming performance of a steam–methane reformer. Fuel, 111:461 – 471, 2013. doi:0.1016/j.fuel.2013.04.078.
• Jianguo Xu and Gilbert F. Froment. Methane steam reforming: Ii. diffusional limitations and reactor simulation. AIChE Journal, 35(1):97–103, 1989. doi:10.1002/aic.690350110.
• Jianguo Xu and Gilbert F. Froment. Methane steam reforming, methanation and water-gas shift: I. intrinsic kinetics. AIChE Journal, 35(1):88–96, 1989. doi:10.1002/aic.690350109.
• Alice Young, Sam Henderson, Liam Buchanan, Daniel Hall, and Catherine Bishop. Failure of commercial extruded catalysts in simple compression and bulk thermal cycling. International Journal of Applied Ceramic Technology, 15(1):74–88, 2018. doi:10.1111/ijac.12788.