基于管流法和旋转法的洗煤泥流变特性比较研究

Comparative study on rheological characteristics of coal sludge based on tube-flowing method and rotation method

流变特性对煤泥资源化利用过程中的管道设计及输送至关重要。通过采用管流法和旋转法测定洗煤泥的流变特性,探究了含水率、剪切速率、剪切时间等多种因素对煤泥流变特性的影响,并比较了两种流变特性测定方法。结果表明:洗煤泥的剪切应力随着剪切速率的增大而增大,含水率对高浓度煤泥膏体的流变特性影响更加显著。含水率为27.6%的煤泥膏体属于宾汉性流体,而含水率为31.2%和35.3%的煤泥膏体属于屈服假塑性流体。剪切时间对含水率为27.6%的洗煤泥流变特性影响更加显著。通过比较管流法和旋转法测得的煤泥流变特性,发现两者在含水率对煤泥流变特性的影响上呈现相同的规律,但所测数值有较大差异。管流法可以提供管道泵送过程中的单位管长压降,对煤泥输送管道的设计更具指导价值;旋转法可提供剪切时间对煤泥膏体流变特性的影响规律,有助于获取合适的搅拌预处理方案。将两种方法结合评估煤泥的流变特性,对煤泥炉前泵送管道及方案设计更有现实意义。

Rheological characteristics are very important for pipeline design and transportation in the process of coal slime resource utilization.The rheological properties of coal slime were measured by the tube-flowing method and rotation method,and the effects of moisture content,shear rate,shear time and other factors on the rheological properties of coal slime were investigated.The results show that the shear stress of the washed slime increases with the increase of the shear rate,and the moisture content has a more significant effect on the rheological properties of the high-quality slime paste.The slime paste with 27.6%moisture content belongs to the Bingham fluid,while the slime paste with 31.2%and 35.3%moisture content belongs to the yield pseudoplastic fluid.Shear time has a more evident effect on the rheological characteristics of coal slime with 27.6%moisture content.By comparing the rheological characteristics of slime measured by the tube-flowing method and rotation method,it is found that the influence of moisture content on the rheological characteristics of coal slime presents the same law.However,the measured values are quite different.The tube-flowing method can provide the pressure drop per unit pipe length during the pipeline pumping process,which has more guiding value for the design of the coal slime transportation pipeline.The rotation method can characterize the influence of shear time on the rheological properties of slime paste,which is conducive to obtaining an appropriate mixing pretreatment scheme.The combination of these two methods to comprehensively evaluate the rheological properties of slime is of more practical significance to the design of pumping pipeline and scheme in front of slime furnace.