潮湿细粒煤脉动流态化脱灰与脱水的过程强化机理

The clean and efficient utilization of fossil energy is the requirement of medium-and-long-term development of science and technology in energy field. Dry beneficiation and upgrading of low-rank coal is hotspots all over the world. Dense-phase fluidized bed can be used for dry beneficiation efficiently for coarse coal. In this project, the hot and active pulsating air flow is introduced into the dense-phase fluidized bed, and a dense-phase gas-vibro separating fluidized bed is generated. The research contents are listed as follows: the kinetics of heavy medium and coal particles, enhancement mechanism of bed stability, mass and heat transfer of multiphase, characteristics and enhancement mechanism of de-ash and de-water in gas-vibro fluidized bed. The bed stability can be improved by the pulsating air flow, and -6mm fine coal can be separated efficiently. The synergistic effect of temperature, concentration, pressure and pulsating air flow can be used to enhance the process of de-ash and de-water. Finally, the fine coal with high moisture can be upgraded using the gas-vibro fluidized bed.

清洁高效的利用煤炭等化石能源是我国能源领域中长期科技发展的要求。煤炭高效干法分选和低阶煤的干燥提质是近年来的研究热点和难点。浓相气固流化床分选技术能够实现块煤的高效干法分选。本项目提出在浓相气固流化床中引入脉动热空气，形成热态的稠密脉动分选流化床，降低有效分选粒度下限，提高传质传热效率。研究脉动流化床中多组分多尺度颗粒动力学及床层稳定强化机理、多相间的传质与传热、潮湿细粒煤脱灰与脱水特性及其过程强化机理等。采用气流振动能量提高床层稳定性，实现-6mm细粒煤的有效分选，通过温度、浓度、压力和气流振动等多驱动势协同作用，解决分选与干燥在竞争中协调的问题，强化潮湿细粒煤脱灰与脱水过程，实现分选与干燥的一体化。

随着煤炭资源大量的开采利用，我国高质量煤炭的储量急剧下降，劣质煤的开采和利用占据主导地位。我国褐煤资源储量丰富，强化对褐煤脱水、脱灰、提质技术的研究成为劣质煤利用的发展规律与发展态势。气固流化床以其优异的传质传热特性，广泛应用于化工、干燥、燃烧和造粒等领域，空气重介质流化床（分选流化床）用于煤炭干法分选是气固流化床技术应用的创新与拓展，但受床层中气泡和加重质运动的影响，空气重介质流化床对细粒煤（-6mm）的分选效果差。且现有的褐煤干燥提质技术虽然具有较好的干燥脱水效果，但在干燥过程中只能降低产品水分，无法进行褐煤的脱灰提质，若要对褐煤进行分选降灰，需单独增设选煤工艺，然而褐煤等低阶煤遇水容易泥化，采用传统的湿法分选方法无法进行有效的分选。.本项目提出将空气重介质流化床的持续气流改为流量周期性变化的脉动气流，形成稠密脉动分选流化床，采用气流强制振动能量改善空气重介质流化床的流态化质量，提高床层密度的 均匀稳定性，强化颗粒的重力分选过程，实现-6mm细粒煤的高效干法分选。并将稠密脉动分选流化床的流化气体温度由常温提升至100～200℃，利用脉动流化床传质传热优势，对潮湿细粒煤进行干燥提质。其中表面水分脱除率为98%，精煤灰分减少了19.11%，可能偏差E达到0.10g/cm3，发热量提高了1866kcal/kg。为潮湿细粒煤脱灰与脱水过程的一体化奠定理论基础。