褐煤中水分对油煤浆流变性质的影响

针对云南褐煤,用真空干燥脱水和恒温恒湿箱处理获得了不同含水率的褐煤,在常温常压(t=19.3℃,p=1.01×105Pa)条件下研究了褐煤含水率对油煤浆流变特性的影响。研究表明,原料煤含水率对油煤浆黏度和流变特性有一定的影响。随褐煤含水率增加,油煤浆黏度先减小后增加。油煤浆浓度不同,剪切速率不同,黏度出现最低值的含水率值wmin也不同。浓度为45.45%的油煤浆,剪切速率小于4.4 s-1时,wmin为9.20%;剪切速率大于4.4 s-1时,wmin为7.80%。浓度为55.56%的油煤浆,剪切速率小于1.32 s-1时,wmin为7.40%;剪切速率大于1.32 s-1时,wmin为10.00%。随剪切速率变化,油煤浆黏度上下行曲线之间形成滞后环,表明油煤浆体系有触变性,并且不同含水率煤浆体系触变性不同,含水率越大,触变性越明显。实验中不同含水率褐煤油煤浆都属于假塑性流体,且含水率对模型参数有一定的影响。

Effect of moisture on rheological properties of brown coal-oil slurry

Yunnan brown coals with different moisture contents were prepared by vacuum-drying and thermostatic and humidistatic treatment, and the effects of moisture on the rheological behavior of brown coal-oil slurries were studied at atmospheric pressure and room temperature(t=19.3 ℃, p=1.01×10⁵ Pa). It is found that the moisture contents in raw coals have influences on the rheological properties of brown coal-oil slurries. The viscosity of the slurry decreases first and then increases with the increase in moisture. The moisture content ω_min at which the lowest viscosity occurs varies with shear rates and coal loadings. ω_min is 9.20% at the shear stress less than 4.4 s^-1 and 7.80% at the shear stress greater than 4.4 s^-1 as the coal concentration is 45.45%. ω_min becomes 7.40% at the shear stress less than 1.32 s^-1 and 10.00% at the shear stress greater than 1.32 s^-1 as the coal concentration is 55.56%. The thixotropy of brown coal-oil slurries is different for different moisture contents, and is enhanced with the decrease in the moisture contents. Brown coal-oil slurries containing moisture of various contents are pseudoplastic fluid, and the moisture contents also have some effects on the parameters of the rheological model.