【摘要】 <正> 一、问题的提出输油管正确的热工计算方法,是合理设计加热站的加热负荷、站间距及输油管顺利投产和运行管理的重要科学依据。地下输油管是浅埋构筑物,其传热过程受到地面温度年变化的影响。根据我国在华北某地区的观测,地面以下一米处地温年波幅达10℃,两米处为7.25℃。因此,输油管起输、常输和停输的传热过程是边值条件较为复杂的三维非稳定传热问题。目前,输油管的热工计算方法是应用汇源法求解得到的,为此,对定解条件作了如下更多还原

【Abstract】 Correct thermal calculation of underground oil pipeline is essential to the rational design of heating stations as well as safe and economical pipeline operation.Considering the effect of the annual temperature fluc- tuations of surface on oil transported during start-up,normal pumping and shut-down of pipeline,heat transfer processes are treated as two-di- mensional unsteady state problems with complicated boundary conditions. Equations used in thermal calculations for normal operations are pre- sented indicating temperature variations at the station’s outlet,which may be used in the mathematical model for continuous and automatic control of the station.Equations for pipeline shut-down are also given to calculate temperature variations of oil and pipe-wall with time for determining the thickness of gelled oil and estimating the maximum allowable time of shut-down for repairs.更多还原