UNS: Collaborative Research: Multiple-Scale Investigation of Chemical Looping with Oxygen Carrier Uncoupling

合作提案#1511818/P.I.：田，汉江#1510900/P.I.：李，范兴这项研究有望为解决燃煤二氧化碳捕获和封存问题提供基础知识和科学基础，燃煤二氧化碳捕获和封存是环境可持续发展最关键的领域之一。在各种CCS技术中，CLU是一种针对固体燃料(如煤炭)燃烧进行优化的CLC方案，是最有前途的选择之一。通过基于金属氧化物的氧气载体能够在不同的氧气分压下释放和吸收氧气，CLU通过循环反应将煤炭间接转化为单独的富含二氧化碳和氮气的烟道气。因此，自然避免了与二氧化碳分离相关的能源损失。与氧燃料燃烧相比，利用氧载体实现氧的快速转移取代了能源密集型的低温氧分离，从而显著提高了碳捕获效率。到目前为止，由于缺乏对煤-氧载体相互作用机理的科学理解，这一领域的大多数研究都遵循反复试验的方法。这种低效的方法不仅在技术和经济上带来了潜在的不确定性，而且还限制了CLC的开发和实施的进度。这项研究是由迫切需要发展新的科学理解和创新的工具和方法来研究煤-氧载体相互作用和动力学、氧-载体优化以及反应器和过程模拟的迫切需要推动的。这项研究将为从原子水平发展到反应堆和工艺规模奠定坚实的理论基础。这些基础研究也有望带来令人振奋的新催化系统和反应器结构的发现，有利于其他研究领域，如制氧、生物质燃烧、煤/生物质气化和SOx/NOx排放控制的新方案。氧载流解偶联的化学链燃烧，又名。CLU代表了一种独特的燃烧方案，它与传统的燃烧过程直接相关，但又有显著的不同。它允许高效的化石燃料燃烧，并将二氧化碳分离的能源损失降至最低。这个多学科团队由美国和中国在传统燃烧和化学循环燃烧(CLC)领域的六个领先研究小组发起，汇集了顶尖的化学工程师、热工、机械工程师和催化科学家，以回答燃烧动力学、表面反应、氧载体开发、热工和反应器/过程建模等关键且相互关联的科学问题，范围从原子水平到反应器和过程尺度。从拟议的研究中获得的基本发现，预计将大大加快开发和部署用于集成二氧化碳捕获的高效煤炭燃烧的CLU。这些基础研究集中在四个方面：1)金属氧化物辅助的半焦/挥发分氧化过程中的晶格氧扩散、表面反应和气相燃烧动力学；2)氧载体与灰和杂质的相互作用；3)循环床CLC反应器中氧载体的稳定性和性能评价；4)反应器和过程建模。这些合作赠款由美国国家科学基金会国际科学与工程分部(ISE)的全球风险基金(GVF)和CBET/ENG燃烧和火灾与环境可持续项目共同资助。

Collaborative Proposals#1511818 / P.I.: Tian, Hanjiang#1510900 / P.I.: Li, FanxingThis research is expected to provide fundamental knowledge and scientific foundation for addressing CO2 capture and sequestration (CCS) from coal combustion, one of the most crucial areas of environmental sustainability. Among various CCS technologies, CLOU, a CLC scheme optimized for solid-fuel combustion (e.g., coal), represents one of the most promising options. Enabled by metal-oxide-based oxygen carriers capable of oxygen release and uptake under varying oxygen partial pressures, CLOU indirectly converts coal into separate streams of sequestration-ready CO2- and N2-rich flue gas via cyclic reactions. Consequently, the energy penalty associated with CO2 separation is inherently avoided. Compared to oxy-fuel combustion, the energy-intensive cryogenic oxygen separation is replaced by facile oxygen transfer enabled by the oxygen carrier, leading to significant improvement of carbon-capture efficiency. To date, most research in this area follows a trial-and-error approach due to lack of scientific understanding on the mechanism of coal-oxygen carrier interaction. Such an inefficient approach not only introduces potential uncertainties in technology and economics, but it also limits the progress of the development and implementation of CLC. The research is driven by the urgent needs for developing new scientific understanding and innovative tools and methodologies to investigate coal-oxygen carrier interaction and kinetics, oxygen-carrier optimization, and reactor and process simulations. The research will establish a solid theoretical groundwork for CLOU development from atomic level to reactor and process scales. These fundamental studies also are expected to lead to exciting discovery of novel catalytic-system and reactor configurations benefiting other research areas such as novel schemes for oxygen production, biomass combustion, coal/biomass gasification, and SOx/NOx emission control. Chemical Looping Combustion with Oxygen Carrier Uncoupling, a.k.a. CLOU, represents a unique combustion scheme that is directly related yet notably different from conventional combustion processes. It allows efficient fossil fuel combustion with minimal energy penalty for CO2 separation. Initiated by six leading U.S./Chinese research groups in the areas of both conventional and Chemical Looping Combustion (CLC), this multidisciplinary team brings together top chemical engineers, thermal engineers, mechanical engineers, and catalysis scientists to answer critical, interrelated scientific questions in combustion kinetics, surface reactions, oxygen-carrier development, thermal engineering, and reactor/process modeling, spanning from atomic level to reactor and process scales. Fundamental findings obtained from the proposed research are expected to significantly accelerate the development and deployment of CLOU for efficient coal combustion with integrated CO2 capture. The fundamental research focuses on four aspects: 1) lattice oxygen diffusion, surface reaction, and gas-phase combustion kinetics in a metal-oxide-assisted char/volatile oxidation scheme; 2) oxygen-carrier interactions with coal ash and impurities; 3) oxygen-carrier stability and performance evaluation in circulating fluidized bed CLC reactors, and 4) reactor and process modeling.These collaborative grants are co-funded by the Global Venture Fund (GVF) of NSF's International Science and Engineering section (ISE) and the CBET/ENG Combustion and Fire and Environmental Sustainability programs.