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    基于流态化活化的煤基燃料O2/CO2燃烧碳捕集技术研究进展

    Research progress of carbon capture technology for O2/CO2 combustion of coal-based fuels based on fluidization activation

    • 摘要: 我国承诺将在2030年前推动CO2排放量达到峰值,进而在2060年前达成碳中和目标。目前,煤炭等化石能源在我国能源消费结构中仍占据相当比重,对保障能源供应的稳定性与安全性意义重大。采用碳捕集技术,可以有效降低碳排放,甚至实现近零排放,助力能源转型稳步推进。富氧燃烧是燃烧中碳捕集的核心工艺,具有CO2浓度高、捕集成本低、燃烧效率高、污染物排放少等优势,因而具有广阔的应用前景。为拓宽富氧燃烧技术的燃料适应性并增强其与工业领域的适配性,提出了碳基原料流态化活化技术新思路,采用该技术可制备气固活化态类气体燃料,进而通过类气体燃料的富氧燃烧,实现碳捕集;或通过类气体燃料的富氧气化,制取富CO合成气,用于化学品合成,实现CO2资源化利用。首先剖析了流态化活化技术的基本原理,阐明了CO2在该过程中的作用机制。然后,全面综述了碳基原料经流态化活化后所得煤气的特性和活化半焦的特性,重点探究了活化温度、碳与CO2物质的量比(CC比)、反应气氛、氧气浓度及燃料种类等对煤气组成、煤气产率、煤气热值的影响,同时还研究了这些因素对活化半焦粒径分布、微观形貌、比表面积、孔隙结构、碳架结构、反应活性等的影响规律。此外,梳理了气固活化态类气体燃料在O2/CO2气氛下的气化特性,考察了燃料特性、CO2浓度和O2/C物质的量比等对气化性能指标的影响;梳理了气固活化态类气体燃料在O2/CO2气氛下的燃烧特性,总结归纳了NOx排放规律及反应调控机理。最后,对流态化活化技术进行了总结和展望,以期为工业领域燃烧中碳捕集技术及CO2的大规模资源化利用提供理论依据和数据支撑。

       

      Abstract: To address climate change and reduce carbon emissions, China has pledged to peak CO2 emissions before 2030 and achieve carbon neutrality by 2060. Currently, fossil fuels such as coal still occupy a significant proportion in China’s energy consumption structure, which is of great significance for ensuring the stability and safety of energy supply. Utilizing carbon capture technology can effectively reduce carbon emissions, even achieving near-zero emissions, thereby facilitating a steady transition in energy sources. Oxygen-enrichment combustion is the core process in carbon capture during combustion. It has advantages such as high CO2 concentration, low capture cost, high combustion efficiency, and low pollutant emissions, and thus has broad application prospects. To broaden the fuel adaptability of oxygen-enrichment combustion technology and enhance its compatibility with industrial fields, the authors proposed a new idea of the fluidized activation technology of carbon-based raw materials. By using this technology, gas-solid activated like-gas fuel can be prepared. Subsequently, carbon capture can be achieved through oxygen-enriched combustion. Alternatively, the gas-solid activated like-gas fuel can generate CO-rich syngas via oxygen-enriched gasification, which could offer sufficient and high-grade raw materials and key reaction fundamentals for the production of chemicals with CO as the feedstock, thereby achieving the utilization of CO₂ and carbon fixation. Firstly, the basic principle of fluidized activation technology is analyzed, and the functioning mechanism of CO2 in this process is clarified. The characteristics of the produced fuel gas and the activated semi-char from carbon-based raw materials after fluidized activation process are reviewed. The emphasis is on exploring the effects of activation temperature, molar ratio of carbon to CO2 (C/C ratio), reaction atmosphere, oxygen concentration, and fuel type on the gas composition, gas yield, and gas calorific value, as well as the influence on the particle size distribution, microstructure, specific surface area, pore structure, carbon framework structure, and reactivity of the activated semi-char. The gasification characteristics of gas-solid activated like-gas-fuel in an O2/CO2 atmosphere are summarized, and the effects of fuel type, CO2 concentration, and O2/C molar ratio on gasification performance are compared. The combustion characteristics of gas-solid activated like-gas-fuel in an O2/CO2 atmosphere are also summarized, and the NOx emission properties and reaction control mechanisms are analyzed. Finally, the fluidized activation technology is summarized and prospected, with the hope of providing a theoretical basis and data support for in-combustion carbon capture technology in the industrial field and the large-scale resource utilization of CO2.

       

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