468501 Development of a Computationally Efficient Model of a Packed-Bed Membrane Reactor for the Oxidative Coupling of Methane

Wednesday, November 16, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Alberto Penteado, Mi Jin Kim, Hamid Godini, Erik Esche, Jens-Uwe Repke and Eva Speelmanns, Process Dynamics and Operations Group, Technische Universität Berlin, Berlin, Germany

The oxidative coupling of methane (OCM) is a catalytic path for converting methane into ethene. Thus, it enables the production of valuable chemicals directly from C1. Different reactor concepts are currently under investigation, such as fluidized-bed reactor and packed-bed membrane reactors, to allow for a better handling of the exothermicity of the reaction network, which is a major concern in packed-bed reactors. In this sense, packed-bed membrane reactors offer significant potential due to the possibility of dosing the oxygen reactant feed along the reactor’s length. This helps to sustain milder reaction conditions (T<1300K and p=102 kPa) by keeping higher methane to oxygen ratios, and avoids the formation of hot spots, ultimately leading to higher selectivity and yield.

The appearance of radial concentration and temperature gradients means that such reactors cannot be accurately described by standard one-dimensional models. On the other hand, the use of two-dimensional models greatly increases computational effort, often making them unsuitable for flowsheeting or superstructure optimization applications. In this contribution, a one-dimensional model for the OCM membrane reactor is developed and effectiveness factors based on the Thiele modulus are introduced to better mimic the two-dimensional behavior and fitted to achieve experimentally observed performances. The model is intended to offer a reasonable balance between accuracy, measured by comparison with mini-plants experimental results, and computation time, measured by comparison with a simpler one-dimensional model and a more complex two-dimensional model.

The main model features and the workflow for its implementation will be described during the presentation. The model validation and simulation results will be presented and discussed. The application of the model in combination with the downstream separation units in the context of the synthesis and design of new OCM process structures will be highlighted.

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