卧螺离心机用于盐泥固液分离时转鼓转速对流场特性的影响

对矿井采卤制盐工艺产生的盐泥使用卧螺离心机进行固液分离，应用计算流体力学软件Fluent，基于多相流Eulerian模型、RNG k-ε湍流模型及多重参考系（MRF）方法，对卧螺离心机流体域进行三维数值模拟，采用仿真与实验相结合的方式，研究了转鼓转速与分离特性的关系，结果表明：卧螺离心机在考虑螺旋叶片情况下比忽略螺旋叶片时切向速度滞后系数有明显提升；提出修正离心液压的概念，通过该理论数值证明分离液静压值与理论值的误差源于切向速度的滞后；当转鼓转速达3000r/min以上继续提高时，沉渣固相质量分数不会随之继续增大；分离液中固相微粒的沉降速度随转速增大会小幅均匀增大；实验表明卧螺离心机用于高浓度卤水高速离心时，将在径向产生一定程度的NaCl浓度梯度，溶质浓度在分离液外层较高，内层较低。

Effect of drum rotational speed on flow field characteristics of decanter centrifuge for solid-liquid separation of salt sludge

The salt sludge produced by the mine brine production process uses a decanter centrifuge for solid-liquid separation. Based on the Eulerian multiphase flow model and RNG k-ε turbulence model in a multiple coordinate reference system, the three-dimensional fluid domain of decanter centrifuge was numerically simulated with a computational fluid dynamics software Fluent. The relationship between the rotating speed of the drum and the separation characteristics was studied by the combination of simulation and experiments. The results showed that the tangential speed hysteresis coefficient of the decanter centrifuge is obviously improved when considering the spiral blade than when neglecting the spiral blade. The concept of correcting centrifugal hydraulic pressure was proposed. It was numerically proved that the error between the static pressure value and the theoretical value of the separation liquid was due to the lag of the tangential speed. When the drum rotation speed reaches 3000r/min or more and continues to increase, the sediment solid phase mass fraction will not continue to increase. The sedimentation velocity of the solid phase particles in the separation liquid increases slightly with the increase of the rotational speed. Experiments showed that the decanter centrifuge will produce a certain degree of NaCl concentration gradient in the radial direction when the high concentration brine is centrifuged at high speed. The solute concentration is higher in the outer layer of the separation liquid and lower in the inner layer.