Abstract
Long-distance pipelines transporting multiple product oils such as gasoline, diesel and jet fuel, are important facilities for transporting fossil energy. One major concern in operation is the energy consumption of the pipeline. Energy consumption should be made optimized tracking batches of oils and cutting mixed oil, which requires an accurate prediction of concentration curve. In engineering, the concentration curve is usually assumed to be symmetric, but it is actually asymmetric, which may lead to estimation errors. Thus, the asymmetric concentration of mixed oil should be studied. The formation mechanism of the asymmetry of concentration curve has not been clearly clarified. A new method is proposed to measure the asymmetry of the concentration curve. Quantitative analysis is carried out for each factor on the asymmetry distribution of concentration curve. Based on the convection–diffusion equation, a modified oil-mixing model considering near wall adsorption effect is established. The model shows a good agreement with the Jablonski empirical formula. The error, compared with the experimental results, is less than 5%. The main findings are: (1) deviation volume has a negative correlation with pipe diameter and mean velocity; (2) adsorption coefficient has a greater impact on the length ratio of front and tail oil than diffusion coefficient; (3) the influence of all factors considered on the total length of mixed oil, front oil, tail oil and trail oil are basically the same; (4) if the limit of adsorption concentration in adsorption layer is 1, the reasonable value of adsorption coefficient a and b should be around 0.4. The results reveal the mechanism of asymmetric concentration of product oils and can provide practical suggestions to deal with the mixed oil.
Highlights
An efficient way to transport different types of product oils over a long distance is to use one pipeline to transport the different oils sequentially because the construction of multiple pipelines would require much larger investments and energy consumption
The front part, i.e., the part where the mixed oil head is located, is the left part of the curve, where the oil concentration before it is greater than or equal to 50%
The back part, i.e., the part where the mixed oil tail is located, is the right half of the curve, where the oil concentration of rear oil is greater than 50%
Summary
An efficient way to transport different types of product oils over a long distance is to use one pipeline to transport the different oils sequentially because the construction of multiple pipelines would require much larger investments and energy consumption. A long-distance pipeline has several mixed oil sections. Oil transportation enterprises require the mixed oil sections to be as few and short as possible, to ensure a high-quality product. This requires scheduling, batch interface tracking and mixed oil cutting in engineering. The complexity of these operations increase with the increasing types of product oil and the branch points [2]. Due to the high efficiency of computer-aided programming of this complex
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