油田污水气浮选沉降罐溶气单元工艺结构优化

Process Structure Optimization on Dissolved Air Unit in Air Floatation Settling Tank of Oilfield Wastewater

为形成油田污水溶气气浮处理工艺沉降罐的结构改进方案,满足油田污水的不断提效处理,考虑溶气单元布气工艺控制面积及布气工艺控制液位高度,利用多相流混合模型,模拟研究了溶气气浮沉降罐溶气单元工艺结构对油田污水分离性能的影响。研究结果表明:合理的布气环气体释放头布置、布气环布局及布气液位高度有益于获得均衡的配水单元压力场分布、稳定有序的分离流场粒子运动迹线特征及较好的除油、除悬浮物效果;在回流比25%、溶气释放压差0.6 MPa工况下,优化确定溶气单元布气环上均匀分布的气体释放头间距为856 mm,气体释放头数量为22个,布气环布局采用双环形布气结构,其高度控制在沉降罐内10.6~9.7 m的区域;溶气单元在此优化工艺结构下,可使油田污水沉降处理的除油率和悬浮物去除率分别达到65%以上和35%以上,揭示出优化溶气单元工艺结构是实现油田污水高效气浮选处理的有效途径。

In order to form the structural improvement scheme of the dissolved air flotation treatment process settling tank of oilfield wastewater and meet the continuous efficiency-improving treatment of oilfield wastewater, after having considered the air distribution process control area of the dissolved air unit and the liquid level control height of the air distribution process, with the help of multiphase flow mixed model, numerical simulation was conducted to study the influence of the dissolved air unit process structure of the dissolved air flotation settling tank on the separating property of oilfield wastewater. The study results show that reasonable air release head layout of air distribution ring, layout of air distribution ring and air distribution liquid level height are beneficial to obtain balanced pressure field distribution of water distribution unit, stable and orderly particle motion trace characteristics of separation flow field and better oil and suspended matter removal effect;under the working conditions of reflux ratio of 25% and dissolved air release pressure difference of 0.6 MPa, the optimization results are as follows: the spacing of uniformly distributed air release heads on the air distribution ring of dissolved air unit is 856 mm, the number of air release heads is 22, the layout of air distribution ring adopts double-ring air distribution structure, and its height is controlled in the area of 10.6~9.7 m in the settling tank;under such optimized process structure, the dissolved air unit can allow the oil removal rate and suspended matter removal rate of oilfield wastewater settling treatment to be more than 65% and 35% respectively, revealing that optimizing the process structure of dissolved air unit is an effective way to realize the efficient air flotation treatment of oilfield wastewater.