Intelligent catalyst carrier concept with additively manufactured structures made of shape memory alloys for the optimization of the wall heat transfer in tubular reactors

智能催化剂载体概念，具有由形状记忆合金制成的增材制造结构，用于优化管式反应器中的壁传热

• 批准号: 432515505
• 负责人: Professor Dr.-Ing. Hannsjörg Freund
• 金额: --
• 依托单位: Lehrstuhl Werkstoffkunde und Technologie der Metalle
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/432515505?language=en
• 关键词: Intelligent; catalyst; carrier; concept; additively

Cellular structures represent a promising alternative to classical randomly packed bed reactors owing to their very good heat transport characteristics. A key challenge of using cellular structures as catalyst carriers in tubular reactors is the contact of the structure with the tube wall, which in many cases is not sufficient and thus downgrades the overall heat transfer performance. Especially with strongly exo- or endothermic reactions, this inhibition of heat transfer leads to undesirable temperature gradients. Therefore, the main goal of this proposal is to achieve a scientific understanding for the structure-wall interactions in order to predict the design of an optimal wall coupling. Auxetic POCS (periodic open cellular structures) that are additively manufactured (selective electron beam melting, SEBM) from a shape memory alloy (NiTi, Nitinol) represent a particularly suitable and innovative model system for achieving this goal.The additive manufacturing of these POCS via SEBM offers a great degree of freedom almost without any limitations in the design process. To ensure a good wall coupling for exchangeable catalyst carriers, we propose a system that utilizes the auxetic effect. Uniaxial compression is used to decrease the diameter of the structure. The auxetic effect alone, however, would require a constant pressure to keep the structure compressed. This can be circumvented by combining the auxetic effect with the one-way memory effect of a shape memory alloy. Here, the structure is deformed once before insertion into the reactor and then re-expanded to its original shape by an in situ heat treatment inside the reactor. This method represents an elegant approach for ensuring a press fit between the cellular structure and the reactor wall.The use of Nitinol via SEBM is not sufficiently documented in literature and therefore represents a highly interesting research topic. The combination of knowledge about POCS and literature about additive manufacturing of shape memory alloys offers a promising approach to overcome the problem of wall heat transfer limitations in tubular reactors. Numerical models for mechanical and reaction engineering problems build the framework for the well-founded development of improved catalyst carriers. By performing several optimization cycles the most promising design will be identified. Finally, the feasibility and efficiency of this new concept will be demonstrated in a case study based on a reaction system of technological relevance.

由于细胞结构具有良好的传热特性，它是传统随机填充床反应器的一种很有前途的替代方案。在管式反应器中使用细胞结构作为催化剂载体的一个关键挑战是结构与管壁的接触，在许多情况下，这种接触是不够的，从而降低了整体传热性能。特别是在强烈的外热或吸热反应中，这种对传热的抑制会导致不希望出现的温度梯度。因此，本提案的主要目标是实现对结构-墙壁相互作用的科学理解，以便预测最佳墙壁耦合的设计。由形状记忆合金（NiTi, Nitinol）增材制造（选择性电子束熔化，SEBM）的增塑型POCS（周期性开放细胞结构）代表了实现这一目标的特别合适和创新的模型系统。通过SEBM对这些POCS进行增材制造，在设计过程中几乎没有任何限制，提供了很大程度的自由度。为了保证交换性催化剂载体的良好壁耦合，我们提出了一种利用辅生效应的系统。采用单轴压缩来减小结构的直径。然而，单是这种补充效应就需要一个恒定的压力来保持结构的压缩。这可以通过结合形状记忆合金的单向记忆效应来避免。在这里，结构在插入反应器之前变形一次，然后通过反应器内的原位热处理重新膨胀到其原始形状。这种方法代表了一种确保细胞结构和反应器壁之间压合的优雅方法。通过SEBM使用镍钛诺在文献中没有充分的记录，因此代表了一个非常有趣的研究课题。结合有关POCS的知识和形状记忆合金增材制造的文献，为克服管式反应器壁面传热限制的问题提供了一种有前途的方法。力学和反应工程问题的数值模型为改进催化剂载体的开发奠定了良好的基础。通过执行几个优化周期，将确定最有希望的设计。最后，这个新概念的可行性和效率将在一个基于技术相关反应系统的案例研究中得到证明。