埋地热油管道非稳态传热的环道试验
Unsteady heat transfer loop test for buried hot oil pipeline
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摘要: 借助大型埋地工业试验环道, 模拟生产管道的投产预热和停输再启动过程, 开展埋地热油管道传热规律的试验研究, 从蓄热量、等温线等角度对土壤温度场的建立以及停输再启动后土壤温度场的恢复时间等问题进行了关联分析。研究表明: 埋地管道的预热过程, 投油7 d后, 管外土壤等温线形态固定, 但温度值随着时间的延长逐渐上移增大; 投油10 d后, 等温线呈椭圆形分布于管道周围, 水平方向半径为1.2 m, 垂直方向半径为0.9 m; 在距离管壁1.4~2.0 m的范围内, 土壤温度浮动较小。对于计划停输, 再启动后的前3 h, 土壤蓄热量的增长速率最大, 需要保持原油温度的稳定, 在再启动后的前10 h内, 尽量减少工况变动, 以利于土壤温度场的恢复。Abstract: Through the large-scale buried commercial test loop, the process of the pipeline commissioning preheating and the restart after shutdown were simulated, and the experimental research of buried hot oil pipeline heat transfer law was carried out. The relations between the building of soil temperature field and its recovery time after shutdown and restart were analyzed from the aspects of soil heat storage, isotherm and so on. The research results showed that for the process of the buried pipeline preheating, the shape of the soil isotherm around the pipeline was stable after commissioning 7 days, but the temperature was gradually increased with time increasing; the shape of the soil isotherm around the pipeline was oval after commissioning 10 days, the horizontal radius was 1.2 m, and the vertical radius was 0.9 m; the soil temperature variation was small at a distance of 1.4~2.0 m around the pipeline. During the first 3 hours after restart, the growth rate of the soil heat storage was largest. In order to facilitate the recovery of soil temperature field, the stable oil temperature should be kept, and the variation of working conditions should be minimized as possible within the first 10 hours after restart.