G.V. Nesyn, Lead Researcher, NesynGV@niitnn.transneft.ru F.S. Zverev, Laboratory Head M.I. Valiyev, Deputy Director OOO NII Transneft, Moscow, Russia
Up to the present moment, it is not quite clear how the negligible concentrations of high-molecular polymers can significantly, by tens of percent, reduce the hydrodynamic resistance in the flow turbulent conditions. Nevertheless, the found empirical regularities allow to widely apply this phenomenon, which is called Tom effect, in the field of the pipeline transport of hydrocarbon liquids to increase capacity, reduce power consumption, and also the operating pressure that increases pipeline operation safety. Brief review of the equipment for hydrodynamic tests of anti-turbulent additives is given. Laboratory units, which allow to measure the reduction resistance, are required to control the quality of additives, the main criterion — molecular weight of the polymer molecules. It can be estimated by laboratory turbulent rheometer of simple design using the model liquid, for example, light oil fraction. Convenient quantitative criterion for estimating anti-turbulent additive is proposed — the concentration at which half of the maximum possible resistance reduction is observed.
The factor of polymer solubility in the liquid, which along with the molecular weight is the required condition for Tom effect, becomes of greater importance. Polymer, which is soluble in the diesel fuel, can be poorly soluble in the heavy oil. Accordingly, the additive efficiency will vary significantly. In order to keep tracking of the both factors (polymer solubility and molecular weight), it is required to conduct testing at the laboratory hydrodynamic test bench, where it is possible to simulate the conditions of the real pipeline — the same liquid, temperature, flow turbulent conditions. Testing at the stand will not give the quantitative forecast of the additive behavior in real conditions, however, it is possible to make the qualitative assessment. From several additives, it is possible to select the most effective one in the given conditions of the pipeline. Hydrodynamic testing can serve as the feedback when developing the technology for synthesis of the polymer component of the additive.
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