Buried Oil Pipeline In The Hot Oil Temperature Field Numerical Simulation

The heated crude oil transport in pipelines is a complicated problem of three dimension heat transfer and flow process. The temperature distribution of heated crude oil in the pipeline is affected by many factors such as the structure of pipelines, the temperature of environment, the variation of physical properties of the medium around the pipelines, the crude oil flow state and its variation of physical properties, and so far as wax crude oils in the pipelines are concerned, the wax deposition in the pipeline and heat of freezing should be calculated. In this thesis, the crude oil in the pipeline, pipeline, the soil around the pipeline as well as atmosphere take into consideration as an interactive and influencing system, and the conservation law of mass, momentum, and energy balance are applied to describe the buried hot-oil pipeline in the steady or unsteady state and develop some mathematical models for the temperature distribution of hot-oil in the pipeline and the soil around the pipeline. The important content in this thesis is as follows:1. The numerical solution of the temperature distribution of the soil around the pipeline under the condition of the different season and the different operating condition is obtained by using finite element method and the ANSYS software.2. The process of buried hot-oil pipeline during start-up is simulated by the way of numerically simulating technology.3. An equation for calculating temperature distribution in the pipeline profile is deduced from the conservation laws of mass, momentum and energy under some simplified yet sound assumption. The friction and Joule-Thomson effect of the compressible crude oil in the pipeline is not neglect in the formula.4. To do with the phase change and the free convection in the pipeline, the effective specific heat and equivalent thermal conductivity is adopted in thethesis. The temperature distribution of the crude oil, the congeal oil layer, the wax layer, the insulating layer and the soil is solved together by finite element method without take into consideration of the detail of the boundary condition among themselves.5. In the thesis, I analyse and study the unsteady process of the pipeline during the shut down and restart-up and take account of the change of crude oil rheological properties in the same process, some good results are successfully obtained by numerically simulate the unsteady process of the pipelines during the shut down and restart-up under the different condition such as in different seasons, temperature of atmosphere drop rapidly and heavy rain.