School of Energy Science and Engineering, University of Science and Technology of China, Jinzhai Road, Hefei 230026, China; Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Nengyuan Road, Guangzhou 510640, China.
Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Nengyuan Road, Guangzhou 510640, China.
Waste Manag. 2023 Aug 1;168:126-136. doi: 10.1016/j.wasman.2023.06.001. Epub 2023 Jun 7.
Sewage sludge is a major by-product of wastewater treatment, and its unfavorable properties are frequently a key restriction of disposal technologies, resulting in high costs and ineffective waste management. Smoldering combustion is a new technique for disposing of organic solid waste with high moisture content, which efficiently recovers energy with minimal igniting energy requirements. The objective of this study is to investigate the effects of airflow rate on sewage sludge (SS) smoldering combustion by combining experimental and modeling analyses. Results show that air channeling easily forms at the reactor's edge, intensifying the smoldering reaction and forming a concave smoldering front. The minimum airflow rate required for self-sustaining smoldering is 0.3 cm/s. As the airflow rate increases, convective heat transfer becomes dominant over conduction and radiation, resulting in a surge in smoldering temperature and velocity at 0.6 cm/s, followed by a linear increase. The maximum airflow rate at which the smoldering process can propagate stably during SS disposal is 8 cm/s. The expressions of the smoldering characteristics are obtained by using the activation energy asymptotic approach, and the calculated and experimental values show the same trend of variation, with good agreement at low airflow rate conditions. Sensitivity analysis shows that porosity φ is the most crucial parameter affecting smoldering temperature and velocity.
污水污泥是废水处理的主要副产品，其不良性质通常是处理技术的主要限制因素，导致成本高和废物管理效率低下。闷烧燃烧是一种处理高含水量有机固体废物的新技术，它以最小的点火能量需求有效地回收能量。本研究的目的是通过实验和建模分析相结合，研究气流率对污水污泥（SS）闷烧燃烧的影响。结果表明，在反应器边缘容易形成空气通道，从而增强闷烧反应并形成凹形闷烧前沿。自维持闷烧所需的最小气流率为 0.3cm/s。随着气流率的增加，对流传热超过传导和辐射占主导地位，导致闷烧温度和速度在 0.6cm/s 时急剧上升，然后呈线性增加。在 SS 处理过程中，闷烧过程能够稳定传播的最大气流率为 8cm/s。通过使用激活能渐近法获得闷烧特性的表达式，计算值和实验值表现出相同的变化趋势，在低气流率条件下具有良好的一致性。敏感性分析表明，孔隙率φ是影响闷烧温度和速度的最关键参数。
