基于原油最高温度点变化规律分析停输相变传热

Analysis of Heat Transfer Based on the Change Rule of the Highest Temperature Point for Shutdown

采用分区法数学模型,利用等价比热容法处理析蜡潜热问题,追踪停输相变过程中管道内原油最高温度点位置的变化轨迹,确定管道内原油最终凝固位置,提出管道内原油全凝的判断依据。基于最高温度点位置的变化规律将传热过程分为四个阶段,重点讨论了各阶段中自然对流、潜热释放、传热方式转化对最高温度位置点变化的影响,结合Ra数变化分析了自然对流换热影响从强到弱的变化过程。深入探讨了停输相变过程中管道内固相率的变化及不同位置处原油温降曲线的特点。

The partition method mathematical model was established by using of the equivalent heat specially heat capacity method to deal with the problem of wax-appearance latent heat.The position change trajectory of the highest temperature point in the shutdown process for hot oil overhead pipeline was developed,and the final solidification position of crude oil in the pipeline and the judgment of the total crude oil freezing were determined.The heat transfer process was divided into four stages based on the change rule of the position of the highest temperature point,and the effects of natural convection,latent heat release and heat transfer on the change of the maximum temperature position point in each stage were discussed.The change process of natural convection heat transfer influence from strong to weak was analyzed with Ra number change.The change of solid phase ratio in the pipeline and the characteristics of crude oil temperature drop curves at different locations were discussed.