Wang Fei, Tian Nan, Li Chen, Zhang Kai, Zhang Huirong, Zhang Yuanyuan
State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources, Institute of Resources and Environmental Engineering, Shanxi University, Taiyuan 030006, P. R. China.
Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation, North China Electric Power University, Beijing 102206, China.
ACS Omega. 2024 Jul 11;9(29):31986-31997. doi: 10.1021/acsomega.4c03638. eCollection 2024 Jul 23.
Reducing the energy consumption in microwave drying processes is essential for the sustainable management of coal slime. Utilizing a self-constructed microwave thermogravimetric apparatus, the research investigates critical parameters, including microwave power, spherical diameter, and granule size, affecting drying kinetics and energy efficiency. The results show that it was observed that the drying process progresses through three distinct stages, marked by variations in temperature and moisture content: the initial warming phase, a steady drying stage, and a final phase where the drying rate decreases; optimal pellet sizes for efficient moisture evaporation and diffusion were identified, with smaller particles enhancing heat transfer and drying efficiency; and the Nadhari model was determined to best represent the drying kinetics of coal slime under microwave radiation. The findings indicate a positive correlation between drying efficiency and particle size while being inversely related to increased microwave power for smaller granules. A direct positive relationship between moisture migration and increased power levels was established, while an inverse relationship with the enlargement of particle sizes was observed, negatively affecting the efficiency. For granule sizes of 30, 40, and 50 mm, a decrease in activation power was recorded, with values of 8.215 ± 2.301, 7.936 ± 1.547, and 3.393 ± 0.248 W·g, respectively; and through the comparative analysis of energy consumption, it was demonstrated that for coal slurry particles sized 0.15-0.18 mm subjected to a drying duration of 600 s, an increase in power leads to a reduction in drying efficiency, whereas larger diameter contributes to improved efficiency.
降低微波干燥过程中的能源消耗对于煤泥的可持续管理至关重要。利用自行搭建的微波热重分析仪，该研究调查了影响干燥动力学和能源效率的关键参数，包括微波功率、球形直径和颗粒尺寸。结果表明，干燥过程经历三个不同阶段，其特征是温度和水分含量的变化：初始升温阶段、稳定干燥阶段以及干燥速率下降的最后阶段；确定了有效水分蒸发和扩散的最佳颗粒尺寸，较小颗粒可提高传热和干燥效率；并确定Nadhari模型最能代表微波辐射下煤泥的干燥动力学。研究结果表明，干燥效率与颗粒尺寸呈正相关，而对于较小颗粒，与微波功率增加呈负相关。建立了水分迁移与功率水平增加之间的直接正相关关系，同时观察到与颗粒尺寸增大呈负相关，这对效率有负面影响。对于30、40和50毫米的颗粒尺寸，记录到活化功率降低，分别为8.215±2.301、7.936±1.547和3.393±0.248瓦·克；通过能耗比较分析表明，对于尺寸为0.15 - 0.18毫米的煤浆颗粒，干燥持续时间为600秒时，功率增加会导致干燥效率降低，而较大直径有助于提高效率。
