Study On Heat Transfer Of Shutdown And Start-up Of Submarine Oil Pipeline

The submarine oil pipeline transportation has many merits, such as safty, closed, unaffected basically by bad climate and running steady long term. Cruid oil in the ocean, as its high pour-point and viscosity, should be heated in the submarine oil pipeline transportation. Heat transfer of shutdown and start-up is vital in design and plant supervision of submarine oil pipeline. The problem of heat transfer of shutdown and start-up around pipeline in Pohai bay were studied by theory and experiment.1 Heat transfer characteristics and temperature field were studied for submarine oil pipeline. The hemi-infinity seabed simplified as a rectangle area, considered the influence that pipeline and sandy clay temperature field act on each other, a new mathematic model was built and simplified.2 Sandy clay was collected from the seabed as sample,and its heat conductivity, density and specific heat at constant volume were tested under different water content.3 Heat transfer physical model of submarine oil pipeline was built, and the controlled boundary conditions were determined on both steady and shut-down conditions, then simulatied it numerically. Temperature fields of submarine oil pipeline and around sandy clay and its heat flux in steady and shut-down conditions were analyzed with different design parameters.4 Based on start-up characteristics of submarine oil pipeline, the limited rectangle area was simplified as a circle heat transfer area for submarine pipline, which made the heat transfer process simple, and the physical model was established for submarine oil pipeline start-up, so heat-transfer control equations and its boundary conditions were determined. Then simulated the start-up process as cold running, preheated orderly and reversely and etc. The cruid oil temperature, heat flux and sandy clay temperature field were analyzed with different design parameters, which could provide basic data for start-up manufacture of submarine oil pipeline.5 According to operating conditions and similarity theory, experimental model was established for submarine oil pipeline. A suit of experiment equipment was built up.Experimental researched on shutdown and start-up of submarine pipelines under different situation were accomplished. The test data were revised the theory analysis model, and the numerical simulation were verified.The exploration and research in this thesis, provided theory reference and science oundation for shut-down and start-up of submarine oil pipeline.