Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, PR China.
Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, PR China.
Sci Total Environ. 2022 Sep 10;838(Pt 3):156489. doi: 10.1016/j.scitotenv.2022.156489. Epub 2022 Jun 3.
Blending sludge rich in protein and aliphatic hydrocarbons into the high alkali coal (HAC) has been demonstrated to reduce the ash melting temperature of the HAC/sludge mixture, thereby increasing the effectiveness and efficiency of liquid slagging. However, whether the incorporation of sludge can affect the combustion stability of the original coal-fired boiler is still debatable. As the combustion stability of the fuel can directly affect the operational safety of the boiler, it is of great practical value for exploring the effect of sludge incorporation on the combustion performance of HAC. In this work, the thermal behaviour and microscopic properties of individual HAC, municipal sludge (MS) and HAC/MS mixtures were tested using a Thermogravimetric analyser (TGA) and a Fourier transform infrared (FTIR) spectrometer, respectively. The exothermic, thermodynamic and functional group evolution patterns during the combustion of these samples were also evaluated. Ignition temperatures (T) of the HAC/MS mixtures were relatively lower than that of individual HAC, and decreased with the increase in sludge mass ratio (SMR). The synergistic effect of the co-combustion of HAC and MS resulted in a slightly higher total heat release during the combustion of MS10HAC90 (i.e., the mass percentage of MS and HAC is 1:9) than HAC alone, however, the total heat release of the blend decreased progressively with increasing SMR. The experimental values of the average E for all four mixtures were lower than the theoretical values, indicating that the addition of MS lowered the reaction energy barriers of the mixtures. Consumption rates of the principal groups in samples during the oxidation and combustion all tended to increase progressively with increasing SMR. There are three major synergistic effects existing during co-combustion of HAC and MS: (1) the reaction of free radicals with benzene molecules; (2) the interaction of free radicals; and (3) the catalytic effect of alkali and alkaline earth metals. These findings can provide theoretical guidance for the determination of key parameters (mixing ratio) for the blending of HAC and MS, and can fill the research gap in terms of microscopic reactivity and synergistic effects during the co-combustion of HAC and MS.
将富含蛋白质和脂肪族烃的污泥混入高碱煤 (HAC) 中，已被证明可以降低 HAC/污泥混合物的灰熔融温度，从而提高液态渣化的效果和效率。然而，污泥的掺入是否会影响原煤粉锅炉的燃烧稳定性仍存在争议。由于燃料的燃烧稳定性会直接影响锅炉的运行安全性，因此探索污泥掺入对 HAC 燃烧性能的影响具有重要的实际价值。在这项工作中，使用热重分析仪 (TGA) 和傅里叶变换红外光谱仪 (FTIR) 分别测试了单独的 HAC、城市污泥 (MS) 和 HAC/MS 混合物的热行为和微观特性。还评估了这些样品燃烧过程中的放热、热力学和官能团演变模式。HAC/MS 混合物的着火温度 (T) 相对低于单独的 HAC，并且随着污泥质量比 (SMR) 的增加而降低。HAC 和 MS 共燃烧的协同效应导致 MS10HAC90（即 MS 和 HAC 的质量百分比为 1:9）的燃烧过程中总放热量略高于单独的 HAC，但随着 SMR 的增加，混合物的总放热量逐渐降低。所有四种混合物的平均 E 的实验值均低于理论值，表明 MS 的添加降低了混合物的反应能垒。随着 SMR 的增加，样品中主要基团的消耗速率均呈逐渐增加的趋势。HAC 和 MS 共燃烧过程中存在三种主要的协同效应：（1）自由基与苯分子的反应；（2）自由基的相互作用；（3）碱金属和碱土金属的催化作用。这些发现可为确定 HAC 和 MS 共混的关键参数（混合比）提供理论指导，并可填补 HAC 和 MS 共燃烧过程中微观反应性和协同效应研究的空白。
