Large-scale Loop Experiment for Variation of Soil Temperature Field around Pipeline

Experimental study on variation of soil temperature field for hot oil pipelines during preheating and shut-down process is made by means of large-scale loop. Impacts of flowrate variation, raising and dropping of oil temperature and shut-down on soil temperature field are investigated. Frequent shut-down and restart-up are unfavorable for establishing and recovery of temperature field; temperature drop range of soil is decreased with the increase of pipeline distance during shut-down period; and temperature drop magnitude of soil is relative closely to the influence scope of shut-down and temperature drop as well as the quantity of heat obtained and lost at testing points. The understanding of variation law of soil temperature field and the great number of experimental data obtained can be used in inspection and checkout of relative calculation procedures.