Research advances in the influence of temperature on the sequential transportation in product pipeline

Abstract

Sequential transportation is the main way of long-distance transportation for the oil product, whose essence is a coupling process of flow, mass transfer and heat transfer. Thus, like the pressure gradient and the concentration gradient, the heat gradient is one main power source of the mentioned coupling process as well. The previous related study done by researchers both at home and abroad mainly focus on the aspects including the making scheduling plans for batches in the oil product pipeline, the oil batch interface tracking as well as simulation, the scheme optimization for activating pumps, the mechanism of forming mixed oil and the detection of oil leakage. However, all of these works have failed to take the proper factor of temperature into consideration. As for the researches on experiments, the majority of them concentrate on factors such as the flow patterns, the categories of the oil product, and the parameters of the pipeline and on those factors’ influence upon the total amount of the mixed oil. They all have been irrespective of the effect of temperature and corresponding mechanism. Most of the researches regard the pipeline as an isothermal body, which is a postulated condition in their papers. In the background of digital pipeline system and intelligentized management transportation system, both of a better accuracy and reliability are required for the model to deal with the problem mentioned above. Thus, the classical theory regarding mixed oil, coupling of flow and heat transfer, scheduling plans, separation of mixed oil and leakage detection cannot keep up with the pace the development of the pipeline system. At present, researches of the following aspects are in a fledging period: the smearing phenomenon of mixed oil, the scheduling plans making considering nonlinear factors, the scheduling plan optimization considering coupling of hydraulic and thermal factors, the batch interface tracking regarding the oil quality and the three-dimensional transient flow simulation in long-distance pipeline, which need to make a further study shedding light on the detailed mechanism concerning the temperature’s influence. Thus, firstly in the paper, the correlated researches on mixed oil, scheduling plans, heated oil pipelines and batch interface tracking without taking temperature’s influence into account have been summarized and the corresponding defect has been discussed. Next, current status of researches about the temperature’s influence on the mechanism of mixed oil and on the process of mass transfer as well as heat transfer are analyzed and commented, including the related experimental research. The influences are embodied in the change of transport capacity, the vaporization of oil, the decreasing quality of oil, the low accuracy of batch interface tracking, the high risk of mixed oil cutting and the large pressure drop after pipeline shutdown. Correspondingly, the relevant theoretical and experimental studies are not perfect and sufficient. And the empirical formulae or modified coefficient methods presented in these studies are not suitable enough for the industrial applications. At the end of the paper, it is pointed out that based on the development requirements of the pipeline system, the scheduling plan combined with thermal as well as hydraulic factors, the abnormal diffusion considering temperature between different batches, the three-dimensional simulation of compressible multi-phase turbulence and the batch interface tracking in complex pipelines are the major research directions and key issues in the research field.