卧式螺旋沉降离心机粉煤气化灰水的脱水分析与优化

Analysis and Optimization of Dewatering for Coal Gasification Ash Water in Decanter Centrifuge

为了探究适用于粉煤气化灰水的脱水卧式螺旋沉降离心机的结构形式,采用计算流体力学仿真的方法,对卧式螺旋沉降离心机固液分离进行数值模拟。基于现有卧式螺旋沉降离心机进行三维模型建立,对离心机内部不同位置粉煤气化灰水的含水率进行分析,探究其针对粉煤气化灰水的分离特性。研究了转鼓转速、转鼓锥角以及螺旋推进器螺距对排料口粉煤气化灰水的含水率影响。结果表明,卧式螺旋沉降离心机模型内部的粉煤气化灰水的含水率沿左侧大端排液口向右侧小端出料口逐渐降低。在现有卧式螺旋沉降离心机结构形式中,采用2 000 r/min的转速能在较低的能耗下获得较小的含水率,并且通过将现有卧式螺旋沉降离心机转鼓锥角α增大1°~2°,能进一步降低粉煤气化灰水的含水率,而维持螺旋推进器螺距现有尺寸能够保证卧式螺旋离心机的出料口低含水率以及很好的输送沉渣能力。

In order to explore the structure of decanter centrifuge, which is suitable for the dehydration of coal gasification ash water, the numerical simulation of the solid-liquid separation for coal gasification ash water was carried out by the method of computational fluid dynamics simulation. Based on the structure of the decanter centrifuge, a three-dimensional model was established to analyze the water content of the coal gasification ash water in different positions of the centrifuge, and then the separation characteristics of the coal gasification ash water were investigated. The influence of drum rotation rate, drum cone angle and screw propeller pitch on the moisture content of coal gasification ash water at the outlet was studied. The results showed that the water content of coal gasification ash water in the decanter centrifuge model decreases gradually from left to right. In the existing structure of decanter centrifuge, the speed of 2 000 r/min could be used to obtain a smaller water content at lower energy consumption. Moreover, the water content of coal gasification ash water could be further reduced by increasing taper angle α of the existing decanter centrifuge by 1°~2° to optimize the structure. Finally, maintaining the existing pitch size of the screw propeller can ensure low water content and good sediment transport capacity.