Buried Hot Oil Pipeline Running

When oil product is transported through buried hot-oil pipeline, the loss of pressure energy and heat energy is available, which has mutual vinculum and influence. The design, operation and management of buried hot-oil pipeline are more complicated than that of oil transmission pipeline under normal temperature. In order to minimize management cost, it is vital to accurately learn about the heat drop and pressure drop at the normal running state. In addition, the various operating conditions are put up to research. In this way buried hot oil pipeline is taken to study as follows:(1) Through the study of the operational condition at the normal state, the radial heat drop mathematical model, the axial one and the pressure drop mathematical model are established respectively for buried hot oil pipeline. The solutions to these models are also given into account. The radial heat drop mathematical model was solved by finite difference approach, the inner wall's temperature along the pipeline from can be obtained; the axial heat drop mathematical model was solved by the anticipation-revise method, the oil-product's temperature can be obtained; the pressure drop mathematical model was solved by sectionalized calculation method, the oil-product's pressure can be obtained.(2) Through the investigation of heat drop during the shutdown process of buried hot-oil pipeline, radial heat drop model and the axial one are established. As the above mentioned, radial temperature of each section at discretion can be obtained by applying finite difference approach to the radial heat drop mathematical model, and oil-product's temperature along the pipeline can be obtained by applying anticipation-revise to the axial heat drop model.(3) Restart-up after shutdown is studied; and corresponding mathematical model is established. Resolution to mathematical model is discussed in this paper. Control-volume methods are applied to discrete continuity equation, momentum equation and energy equation. The calculation procedures are put forward to resolve discretization equation with the result of the restarting transportation amount, pump station lift and the temperature along the pipeline.(4) The computing method of minimum permitted mass flow is studied with the consideration of frictional heating or not. The formula is induced and solved by the flat sawn method.(5) A buried hot-oil pipeline is calculated as an example, and is serially analyzed to verify the proposed theories.