水焦浆的流变特性与壁面滑移效应

Wall slip behavior and rheological characteristics of coke/water slurry

在浆体流动试验系统上采用不同管径的直管考察了水焦浆的流变特性以及壁面滑移效应对水焦浆流动特性的影响。采用Tikhonov正则化方法确定了水焦浆的真实流变特性和壁面滑移特性。结果表明:浓度为59.8%的水焦浆随剪切速率增大呈现由伪塑性流体到胀塑性流体的转变,浓度增加,水焦浆变为单一的胀塑性流体,当浓度达到63.4%时,水焦浆表现为由胀塑性流体到伪塑性流体的转变;水焦浆的流变特性对滑移速度的变化趋势具有较大影响,滑移速度在水焦浆为胀塑性流体时随剪切应力增加呈加速增加,水焦浆为伪塑性流体时滑移速度随剪切应力的增长速率变化不明显;滑移贡献率的变化趋势迟滞于流变特性曲线。

Experimental researches were carried out on a slurry transportation system to investigate rheological properties and effects of wall slip behavior on flow properties of coke/water slurry flowing in pipes with different diameters.A numerical technique based on Tikhonov regularization was used to determine rheological properties and slip velocity.The results suggested that when coke concentration was 59.8%,coke/water slurry changed from pseudo plastic fluid to dilatant fluid with the increase of shear rate.Then the slurry became dilatant fluid completely with increasing concentration.While coke concentration came up to 63.4%,coke/water slurry changed from dilatant fluid back to pseudo plastic fluid.Rate of slip velocity change with shear stress depended on rheological properties of coke/water slurry.When coke/water slurry was dilatant fluid,the rate of slip velocity change increased sharply with shear stress.But there was no pronounced change with the rate of slip velocity change of pseudo plastic fluid.The change of slippage contribution lagged behind the change of rheological properties.