CFD Evaluation of Six Structured Catalysts Manufactured by Robocasting Demonstrated on Steam Methane Reforming
Abstract
Low CO2 emissions processes and using renewable energy are key drivers for the future of the chemical industry. Innovation at the catalyst and reactor level is essential to address such challenges. Additive manufacturing (AM) is an enabling technology to address the challenges. AM enables a smooth transition to go from the ideation stage to the manufacturing of a prototype. It makes intricate geometries in a relatively easy manner. These two aspects create an extensive rich space of exploration at a speed that was never experienced before. Because of that, a wide range of ideas for new 3D printed innovation catalyst geometries, while on the other hand, limited resources are available to test them in real life at representative reaction conditions. Therefore, there is a need to have tools and knowledge to guide the exploration space to make the ideation and experimentation cycle more efficient. Catalyst geometry design is controlled by the target pressure drop, mass and heat transfers, and reaction performance. Predicting these performances in a three-dimensional space for the case of 3D printing geometries can mainly if not only be done using Computational Fluid Dynamics (CFD). In this work, six new relatively simple 3D geometry designs are created with the rationale to change velocity profile, and radial mixing, while some can be made by the commercially available extrusion process used to make industrial catalysts and other designs can only be done by AM. All these designs have the same dimensions in all aspects except one. It is the rotational angle that is imposed when the extrusion layers are added on top of each other during the 3D printing process. These rotantial angles are 0^o, 9^o, 18^o, 30^o, 45^o, and 90^o. This thesis will consider these cases and study them in detail using CFD. The aim is to evaluate these geometries using momentum, mass, and energy to check how to answer a list of questions. But more important, is to generate experience and knowledge on how to go from a 3D printed geometrical design to CFD and back into the innovation cycle toward making tailored novel catalyst design geometries. Also, this work paves the foundation to start exploring the potential of 3D printing catalysts at TAMUQ and Qatar which has not been done yet. Steam methane reforming is selected as an application reaction case to study how these geometries affect the performance of this well-established industrial reactor, which is of high relevance in Qatar. Results showed that geometry D-0^o and D-90^o have the lowest pressure drops and the ratio of H2 to CO ratio. Geometries D-18^o, D-30^o, and D-45^o showed the highest degree of radial mixing and the highest level of conversion. Overall no optimal catalyst geometry is obtained which showed the optimization challenge needed on the geometrical design that is essential for guiding the AM technology exploration to make tailored designs that meet strict requirements.
Description
Keywords
3D printing, CFD, COMSOL