固-液两相流黑水管道冲蚀磨损的数值模拟研究

Simulation Study on the Erosive Wear of the Black Water Pipeline with Solid-Liquid Flow

煤气化黑水处理系统管道由于其流体介质高含固体颗粒和腐蚀性介质,且工作在高温、高压差环境中,极易受到冲蚀磨损和腐蚀的耦合作用而失效,影响其服役寿命.采用计算流体力学(CFD)方法数值模拟研究了煤气化黑水处理系统固-液两相流管道的冲蚀磨损行为和机理,以及流体介质速度和固体颗粒粒径对管道冲蚀磨损的影响规律,并分析了盲通管和涡室结构对弯管冲蚀磨损行为的优化改善效果.研究结果显示,煤气化黑水处理系统管线的冲蚀高危区主要分布在弯管外拱和变径管等结构突变区域;管道冲蚀磨损行为与其内部流体的运动和颗粒冲击特性有关;管道的冲蚀率均随着流体速度的增加而加剧,而粒径对弯管和变径管冲蚀率的影响并非单调关系,这与颗粒受力作用有关;弯管优化分析显示,涡室结构可以降低弯管的最大冲蚀率,减缓弯管的冲蚀磨损.

For the pipes of coal gasification black water treatment system,due to the high contents of both solid particles and corrosive elements in the flowing fluid media,and their high temperature and high-pressure difference working environment,the inner surface of the pipes are extremely vulnerable to corrosion and erosive wear,thus affecting their service life.In the paper,the computatioanal fluid dynamics method was used to study the erosion behaviors of the solidliquid two-phase flow pipeline in the coal gasification black water system.And the influence rules of flow velocity and solid particle size on the erosion rates of the pipes were also investigated.Meanwhile,two modified elbows with blind pipe and vortex chamber were analyzed respectively to extend the service life.Results indicated that the primary erosion failure positions of the tested pipeline located in the structural abrupt position,such as the extrados of the elbow and the Variable diameter pipe.The flow behaviors of continuous liquid phase inside the pipeline and the impact effect of the discrete solid particles on the pipe wall played a great role in the pipeline erosion.Both the erosion rates of the elbows and variable diameter pipe increased as the fluid velocity increased;however,the influence rules of solid particle size on the erosion rate were not monotonic.A vortex chamber added to the elbow decreased the maximum erosion rate,thus alleviating erosive wear of the elbow and prolonging its service life.