Non-premixed ammonia combustion in tailored ceramic porous inert media

该项目重点研究无碳化学能载体氨和氨/氢混合物的热化学能转换过程。氨被认为是未来的能源和氢载体之一，特别是在长途运输方面，因为它的热性质与丙烷相似，并且它可以很容易地液化以储存和运输，并建立了运输网络。然而，氨的燃烧带来了相当大的挑战。与碳氢化合物相比，其燃烧速度较低，导致火焰稳定性差，氮氧化物形成水平极高，即使是微量水平也具有高毒性，这是三大挑战。应对这些挑战的传统方法是添加高活性燃料（如氢气或甲烷）来解决火焰稳定性问题，在分级富燃料/精益过程中进行转换以解决高NOx形成问题，并进行后处理以避免未燃烧的氨排放。我们提出了一种新的氨在多孔惰性介质（PIM）中非预混燃烧的概念来解决所有的挑战。由于热通过固相再循环，与非PIM燃烧相比，PIM燃烧可以将燃烧速度提高一个数量级以上。热再循环结合固相的热惯性解决了火焰稳定性问题。非预混方式导致初始富燃料或纯燃料流的高温分解氨，而不产生明显的NOx，而通过PIM的流动的良好混合和温度均质效应导致燃烧后区域剩余氨完全耗尽。为了实现这样的概念，需要定制耐高温材料，无论是在几何形状方面还是在热性能的空间分布方面。复合陶瓷材料的PIM结构的增材制造（ADM）需要通过定制的热传导、辐射、分散和流场特性来控制过程。用于氨和氨/氢混合物的非预混PIM燃烧器的基础研究和设计需要一个强大的跨学科研究团队，在PIM中燃烧的高保真实验（EXP， KIT），详细的孔隙分解数值模拟（SIM， KIT）和热冲击和耐腐蚀功能部件的增材制造方法（ADM, TU BAF）。

The project focuses on the thermochemical energy conversion process of the carbon-free chemical energy carrier ammonia and of ammonia/hydrogen mixtures. Ammonia is considered as one of the future energy and hydrogen carriers, especially in terms of long-distance transport since its thermal properties are similar to those of propane and it can easily be liquefied for storage and transport with an established transportation network. However, the combustion of ammonia poses considerable challenges. The three major challenges are its low burning velocity compared to hydrocarbons resulting in poor flame stability, extremely high levels of nitrogen oxide formation and high toxicity even at trace levels. Conventional approaches to address these challenges are the addition of highly reactive fuels like hydrogen or methane to address the issue of flame stability, conversion in staged fuel rich/lean processes to address the high NOx formation and post treatment for avoiding unburnt ammonia emissions. We propose to address all challenges at once by a novel concept for non-premixed combustion of ammonia in Porous Inert Media (PIM). Combustion in PIM can increase burning velocities by more than one order of magnitude compared with non-PIM combustion due to heat recirculation through the solid phase. Heat recirculation combined with the thermal inertia of the solid phase resolves the issue of flame stability. The non-premixed approach results in high temperatures of the initial fuel rich or pure fuel streams decomposing ammonia without significant NOx formation, while the good mixing and temperature homogenization effects by the flow through the PIM lead to a complete burnout of remaining ammonia in a post-combustion zone. In order to realize such concept, tailored high temperature-resistant materials are required, both in terms of geometry as well as spatial distribution of thermal properties. Additive manufacturing (ADM) of PIM structures from composite ceramic materials is needed to control the process through customized properties regarding heat conduction, radiation properties, dispersion and the flow field. The fundamental research and design of the non-premixed PIM burner for ammonia and ammonia/hydrogen-mixtures requires a strong interdisciplinary research team in the fields of high-fidelity experiments for combustion in PIM (EXP, KIT), detailed pore-resolved numerical simulations (SIM, KIT) and additive manufacturing methods for thermal shock and corrosion-resistant functional components (ADM, TU BAF).