煤颗粒分布对油煤浆流变特性的影响

采用神华煤和煤直接液化循环油配制成油煤浆，考察了煤的颗粒大小、颗粒分布以及浓度对煤浆流变特性的影响.试验结果表明：当浓度较低时，煤浆在比较宽的浓度范围内表现为牛顿流体；浓度较高时，表现为具有剪切稀化行为的假塑性流体.利用双峰级配理论，将粗颗粒煤粉加入细颗粒中可降低煤浆体系的黏度.但继续增大粗颗粒在煤粉中的比例，体系的黏度又会增大，而且煤浆的流变性能也发生改变.在试验条件下，粗细颗粒质量百分比为40∶60时体系具有最低的黏度，煤浆性质由同浓度的细颗粒体系的非牛顿流体转变为牛顿流体.因此，改变煤浆体系中煤的颗粒分布可在保持较高浓度时制备出具有较低黏度的油煤浆.

Effect of particle size distribution on the rheology of oil-coal slurries

The rheological behavior of Shenhua coal oil slurry was studied as a function of solids concentration， particle size and size distribution.  At a certain particle size distribution the apparent viscosity of coal slurry increases with the increase of solid concentration.  Coal slurries were found to exhibit a wide spectrum of flow behavior ranging from Newtonian at low concentrations to shear thinning and pseudoplastic with a yield stress at higher concentrations. By adding a narrow sized coarse coal fraction to the finer coal slurry， the flow characteristics optimum coarse to fine particle ratio of 40∶60 exist at which the slurry is Newtonian.  The significant improvement in the rheological behavior with changing the particle size distribution may be explained in terms of spatial rearrangement of the particles， and apparent dilution effect.  The results indicate that， with a careful control of the particle size distribution， it is possible to prepare an optimum oil coal slurry which has a low viscosity but with high solids loadings.