Department of Earth Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China; Shanxi Key Laboratory of Coal and Coal Measure Gas Geology, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China; Institute of Earth Sciences, Heidelberg University, Heidelberg 69120, Germany.
Department of Earth Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China; Shanxi Key Laboratory of Coal and Coal Measure Gas Geology, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 May 5;272:120947. doi: 10.1016/j.saa.2022.120947. Epub 2022 Feb 1.
Fly ash (-FA) from seven typical power plants in Shanxi province (North China) were collected to explore the effect of carbon residues (-CR) structures on their burnout characteristic. Burnout characteristic is expressed by the loss on ignition (LOI) content in fly ash. Raman spectroscopy and Fourier Transform infrared (FTIR) spectroscopy are used to characterize the structure of CR. The structure parameters include Raman parameter (the full width at half maxima (FWHM) ratio of D and G, I/I) and FTIR parameter (asymmetric stretching intensity ratio of CH and CH groups, A(CH)/A(CH)). Three samples come from circulating fluidized bed (CFB), and four samples are from pulverized coal boilers (PC). Then two types of power plants are numbered from one to three according to the increasing degree of feed coal (-C) metamorphism. The CFB-1-FA, CFB-2-FA, and CFB-3-FA have loss on ignition (LOI) of 9.01%, 16.4%, and 21.6% respectively, while the LOI contents are 1.99%, 4.62%, 23.7%, and 5.00% for the PC-1-FA, PC-2-FA, PC-3-FA, and PC-4-FA. The results show that carbon residues in the PC fly ash mainly have the shorter and branched aliphatic side chains with lower A(CH)/A(CH) value. While carbon residues in the CFB fly ash have relatively longer aliphatic chains, and intramolecular aromatization is the main reaction during combustion. The I/I of the CFB carbon residues are generally higher than it for the PC samples, indicating a more ordered structure. Oxygen-deficient environment and the longer residence time at temperature around 900 °C in the CFB boiler promote the ordering progress of the CR. The ordered CR suppresses its burnout and leads to an increase LOI content in fly ash. In turn, sufficient oxygen and temperature around 1200 °C in the PC boiler make the CR further oxidize and decompose. The CR become less ordered and are prone to burn out, resulting in a reduction of the LOI content.
从山西省 7 个典型的火力发电厂收集飞灰（-FA），以探讨碳残基（-CR）结构对其燃尽特性的影响。燃尽特性由飞灰中的灼减（LOI）含量表示。拉曼光谱和傅里叶变换红外（FTIR）光谱用于表征 CR 的结构。结构参数包括拉曼参数（D 和 G 的半峰全宽（FWHM）比，I/I）和 FTIR 参数（CH 和 CH 基团的不对称伸缩强度比，A（CH）/A（CH））。三个样品来自循环流化床（CFB），四个样品来自煤粉锅炉（PC）。然后，根据给煤（-C）变质程度的增加，两种类型的发电厂分别编号为一到三。CFB-1-FA、CFB-2-FA 和 CFB-3-FA 的灼减（LOI）分别为 9.01%、16.4%和 21.6%，而 PC-1-FA、PC-2-FA、PC-3-FA 和 PC-4-FA 的 LOI 含量分别为 1.99%、4.62%、23.7%和 5.00%。结果表明，PC 飞灰中的碳残基主要具有较短且支化的脂肪侧链，A（CH）/A（CH）值较低。而 CFB 飞灰中的碳残基具有相对较长的脂肪链，并且在燃烧过程中，分子内芳构化是主要反应。CFB 碳残基的 I/I 通常高于 PC 样品，表明结构更有序。CFB 锅炉中贫氧环境和 900°C 左右的较长停留时间促进了 CR 的有序化进程。有序的 CR 抑制其燃尽并导致飞灰中 LOI 含量增加。相反，PC 锅炉中充足的氧气和 1200°C 左右的温度使 CR 进一步氧化和分解。CR 变得无序且易于燃尽，导致 LOI 含量降低。
