叠式流化床钙循环煤制氢协同捕集二氧化碳基础研究

Calcium-looping coal gasification can produce hydrogen with in situ carbon dioxide capture. As one of the clean coal conversion technologies, it meets the requirements of sustainable energy. Hydrogen efficiency is not in accord with carbon capture efficiency in calcium-looping coal gasification, i.e. higher gasification temperature is preferred for the carbon conversion and hydrogen efficiency, but it causes the drops of hydrogen concentration and carbon capture efficiency. The activity and stability of calcium sorbent need to be improved for a long operation time. A novel compact fluidized bed, used as a calcium-looping gasifier, is proposed to produce very high concentration hydrogen (>95%). The setup of two inter-connected fluidized beds, a compact fluidized bed and a fluidized bed riser could, will be built for hydrogen production and sorbent regeneration. The project will investigate gas-solid fluid dynamic, the relations between the fluid dynamic and chemical reactions in the two beds, properties of hydrogen-rich gasification and calcium sorbent regeneration. Migration properties of nitrogen and sulfur in coal are also included. Because of the volume variation in the calcium looping, the micro-frames and micro-channels inside the calcium sorbents are to be observed. The reaction mechanism of solid-solid, solid-gas is also to be investigated. Sintering-resistant precursor and incorporating in inert solid matrix are to be added to improve the sorbent activity, properties of anti-attrition and anti-agglomeration in order to find the preparation method of calcium sorbent. This project aims to provide theoretical fundamentals and experimental data for novel hydrogen-rich gasification technology with CO2 capture.

钙循环煤制氢可以实现富氢气化协同捕集二氧化碳，是洁净煤可持续发展的重大需求。由于受气化温度和钙载体吸收二氧化碳特性的限制，现有钙循环煤制氢制氢效率与碳捕集效率低；且钙载体制备技术尚不能满足稳定长效规模化应用的要求。本课题提出了叠式流化床富氢气化方法，可实现制氢效率和碳捕集效率的协同提高，理论上能制取含氢95%以上的合成气。课题将在叠式流化床-流化床提升管双联流化床钙循环煤制氢协同捕集二氧化碳试验装置上，研究气固两相流动与非均相化学反应匹配规律、制氢以及碳捕集特性，揭示煤中氮硫反应途径；基于钙载体循环中体积的变化，研究钙载体微观结构和孔道特性变化规律，对其固-固界面、气-固界面反应机理及反应途径进行解析，从微观层面考察骨架结构的变化规律，添加沸石分子筛和惰性氧化铝对载体改性，探索其设计与制备方法。为开发新型钙循环煤制氢和捕集二氧化碳一体化集成技术，提供理论基础和实验数据。

钙循环煤制氢可以实现富氢气化协同捕集二氧化碳，是洁净煤可持续发展的重大需求。研究以改性钙基吸附剂作为循环载体，深入探究了不同改性方法、不同载体、载体添加量等因素对改性钙基吸附剂的二氧化碳吸附特性、二氧化碳脱附特性以及循环稳定性能等的影响，探索载体微观结构和孔道变化特性，考察高性能钙载体设计与制备方法。采用叠式流化床富氢气化反应器和流化床提升管再生反应器双联流化床，探究了煤制氢协同捕集二氧化碳研究，掌握双联流化床反应器气固两相流动和热化学反应匹配规律。具体研究包括1）制备方法的分析与探究、载体对催化剂性能的影响、双载体对催化剂性能的影响及载体间的相互作用、催化剂的表征以及反应机理与反应途径分析；2）固定床煤、生物质、含油钻屑及污泥的热解与气化实验及机理探究；3）改性钙载体存在条件下的生物质气化动力学特性研究；4）冷态双联叠式流化床的改进与运行调试并对其固体循环流量、压力分布、运行特性以及串气等进行了深入研究；5）设计并成功搭建了新型叠式双流化床热态反应器，特有的鼓泡床+提升管结构有助于增加停留时间，促进反应平衡移动。在该基金的支持下，筛选并先用先进制备方法合成了CaO-MgO-分子筛、CaO-TiO2-分子筛、CaO-Zr/H-ZSM5、Fe-CaO等吸附剂体系，其具备多功能煤转化，促进焦油裂解，增加气体产量，循环性能稳定，抗烧结和团聚能力强等优势。上述制备的钙基吸附剂分别用于含油钻屑的热解特性研究、煤气化制氢研究、生物质气化制富氢合成气研究、污泥的气化实验研究以及相关过程机理探索，并取得了众多的研究成果，详见结题报告正文。研究成果有望为开发新型钙循环煤制氢和捕集二氧化碳一体化集成技术， 理论基础和实验数据。