高碱煤纯烧的灰化学问题及高效燃烧研究进展

Ash chemistry issues and efficient combustion research progress in pure coal combustion of high-alkali coal

  • 摘要: 煤炭在我国的能源消费结构中占有至关主要的地位,新疆地区拥有丰富的煤炭资源储量,是我国重要的能源接续区和战略储备区。新疆地区的煤炭资源,特别是准东煤中碱金属和碱土金属(Alkali metals and Alkaline Earth Metals, AAEMs)含量普遍较高,属于典型高碱煤,可供长期使用。随着新疆地区煤炭资源的大规模开采和利用,高碱煤在燃烧过程中发生的结渣、沾污和腐蚀等问题严重限制了其大规模和高效利用。实现100%纯烧高碱煤是高碱煤利用的重要目标,但解决纯烧过程中涉及的灰问题是首要问题。基于现代多元、分时、动态分方法,利用CiteSpace软件获取近20 a来高碱煤研究领域的4401条文献,对文献结果进行文献聚类分析、关键词凸显分析和时间序列分析,对不同时期的研究热度峰值区间进行了系统分析。指出了该领域未来研究需要关注AAEMs的存在形式与迁移特性、低温共熔物形成机制、燃烧高效利用调控措施等方面。以典型高碱煤为基础,总结了其基本理化特性,重点剖析煤灰碱性组分对煤灰熔融温度的影响和AAEMs的存在形式。在此基础上,调研AAEMs和低温共熔物2个核心方面研究进展,探究AAEMs迁移特性与低温共熔物的生成机制,对煤炭清洁高效利用低碳具有重要意义。然后,将高碱煤燃烧高效利用调控措施归纳为降低AAEMs含量、增加酸性组分和反应器运行与结构优化三大类别,分析了利用措施对缓解高碱煤结渣沾污的原理与效果,并指出对应方法的问题和不足。此外,提出煤粉纯化−燃烧高效利用技术或许是解决高碱煤燃烧高效利用难题的有效手段。最后,双碳背景下对火电提出了灵活性改造需求,火电机组需要提高变负荷调节能力,以保证稳定的功率输出。指出了实现高碱煤燃烧高效利用调控建议和未来研究方向,需要结合地方多样化资源优势并系统地制定整体方案,在全流程精准控制结渣、沾污和腐蚀等难题,实现清洁高效低碳利用。

     

    Abstract: Coal constitutes a pivotal element of China’s energy consumption structure. Xinjiang, which boasts considerable coal deposits, is a crucial energy succession zone and strategic reserve area within China. The coal resources in Xinjiang, particularly the Zhundong variety, typically exhibit elevated concentrations of alkali metals and alkaline earth metals (AAEMs), which are typical high-alkali coal well-suited for prolonged utilisation. The large-scale mining and utilisation of coal resources in Xinjiang has resulted in significant challenges, particularly in the form of slagging, staining and corrosion of high-alkali coal during combustion. These issues have severely limited the large-scale and efficient utilisation of this coal resource. The objective of achieving 100% clean combustion of high-alkali coal represents a significant challenge in the field of high-alkali coal utilisation. However, the primary obstacle lies in the resolution of the ash issue inherent to the clean combustion process. In this paper, about 4401 literatures in the field of high-alkali coal research in the past 20 years were obtained by using CiteSpace software. These literatures were subjected to literature clustering analysis, keyword highlighting analysis and time-series analysis. In addition, the peak interval of the heat of research in different periods was systematically analysed. It is highlighted that the future research in this field should prioritise the investigations into the existence form and migration characteristics of AAEMs, the low-temperature eutectic formation mechanism, and the development of combustion-efficient utilisation regulation measures. Based on a representative high-alkali coal, a summary of the fundamental physicochemical properties was presented, with a particular focus on the impact of the alkaline component of coal ash on the melting temperature of coal ash and the existence form of AAEMs. This study investigates the research progress of two core aspects, namely, AAEMs and low-temperature eutectics, with the objective of exploring the migration characteristics of AAEMs and the generation mechanism of low-temperature eutectics. This is of great significance for the clean and efficient utilisation of coal with low carbon. Subsequently, the regulatory measures for the efficient utilisation of high-alkali coal combustion are categorised into three principal groups: the reduction of AAEMs content, the increase of acidic components, and the optimisation of reactor operation and structure. The principles and effects of the utilisation measures on the mitigation of slagging and staining of high-alkali coals are then analysed, and the shortcomings of the corresponding methods are identified. Furthermore, it is proposed that the coal dust purification-combustion efficient utilisation technology may prove an effective means of solving the problem of efficient utilisation of high-alkali coal combustion. Ultimately, the dual-carbon context underscores the necessity for thermal power units to enhance their variable load regulation capabilities, thereby ensuring a stable power output. This paper puts forward suggestions and proposes avenues for future research in order to achieve the efficient utilisation of high-alkali coal combustion. It is essential that these are combined with local diversified resource advantages and that an overall plan is formulated in order to accurately control the problems of slagging, staining and corrosion throughout the entire process. This will enable the clean, efficient and low-carbon utilisation of the resource to be achieved.

     

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