水分对无烟煤破碎行为和研磨能耗的影响

煤中水分赋存形态和含量的变化会改变煤炭物理特性和孔隙结构,进而影响其破碎过程。为研究煤炭所含水分对其破碎行为的影响,以无烟煤为研究对象,利用加装功率测量装置的哈氏可磨仪模拟中速磨煤机内的破碎环境,对不同含水量煤样开展多时间批次的单独与混合破碎试验,并研究水分对煤炭破碎速率、煤粉细度及研磨能耗的影响。试验结果表明:相比于原始煤样,均化浸泡煤样单独破碎时初始粒级物料破碎速率因含水量的增加明显减小,其可磨性指数随水分增加先减小后增大,煤粉细度t10与含水量呈正相关关系。干、湿煤样混合破碎时13.34%含水量样品破碎速率和细粒级物料生成速率远大于相同水分的均化浸泡煤样,且其可磨性指数大于原煤;其他含水量的混配煤样可磨性指数略小于均化浸泡煤样,此差异随含水量增加而变大,而破碎速率和细粒级物料产率与均化浸泡煤样差别较小。经典能量—粒度关系模型可用来表征不同水分梯度样品单独和混合破碎过程,内、外水分不同程度降低了无烟煤抵抗破碎的能力,单独破碎时含水量增加可显著提高能量效率;将含水量参数引入能耗模型,实现对多梯度水分煤样破碎过程的表征。通过探究煤中含水量对煤炭破碎能耗的影响机理,揭示煤炭破碎过程中能量损失方式并为优化煤炭破碎工艺、降低能耗提供理论指导。

Numerical analysis of grinding power consumption of a vertical planetary mill

Planetary wheel rolling on a coal-bed was simplified as rigid wheel rolling on the coal-bed with a rigid base when a Ver- tical planetary mill(VPM)is running.Based on our analysis,we conclude that the Bekker formulation for computing rolling resis- tance is not applicable to calculate directly the rolling resistance of the wheel.According to the principle of the Bekker apparatus,pressure-sinkage curves were obtained by tests on a piece of mono-axial consolidation apparatus used in soil-mechanics.The de- formation modulus of the coal-bed was calculated using elastic mechanics.A finite element model of the planetary wheel coal-bed was built up by the use of a rigid and a Drucker-Prager material model in LS-DYNA.According to the simulation results,the wheel rolling resistance,the grinding power consumption and the motor power of the mill were calculated and the mistake in the initial design of the mill was modified.The simulation results agree well with the results of the semi-industrial tests.