Definition and analysis of overall heat-transfer coefficient at the sections of “hot” export petroleum pipeline operating in northern winter conditions

Abstract

Background. Receiving information on overall heat-transfer coefficient of pipeline pumping down the heat oil is required for resolving a number of process challenges: definition of specific cooling-off intensity of delivered petroleum, optimization of delivery processes, insulation efficiency assessment of pipeline sections etc. Aim. The actual values of the heat transfer coefficients are the most reliable basis for the implementation of optimization and technological calculations during thermohydraulic modeling and development of measures (a) to save energy during hot pumping and (b) to increase the reliability of the “hot” pipeline in order to exclude the possibility of its self-stopping and “freezing”. In the context of assessing the technological reliability of pumping, the determination and analysis of the total heat transfer coefficient for the sections of the oil pipeline were carried out and the capabilities of this methodological approach were demonstrated. Materials and methods. In the article, by the example of 266-kilometer long export pipeline (Ø 300 mm), functioning in «hot» delivery mode is presented the calculation process of defining the actual values of overall heat-transfer coefficient in route sections, and is done the analysis of this coefficient values, operation heating mode of the pipeline and their related factors of technological reliability of oil delivery process. Results. The difference in the values of the overall heat transfer coefficient at the sections of the pipeline is shown, which allows us to come to a practical conclusion about the different intensities of the thermal processes occurring in its different linear sections (aboveground, underground with intersection of marshy soils and rivers, with and without thermal insulation, operating in non-isothermal and isothermal modes). Conclusions. The proposed approach to determining the actual values of the total heat transfer coefficient for sections of the “hot” oil pipeline in combination with the analysis of the data obtained provides opportunities that are largely in demand from a methodological point of view and extremely important from a practical standpoint.