Abstract
The paper reports the results of a study into a method of estimating the level of power/energy reduction needed for pumping highly viscous hydrophobic liquids. The effect of reducing the flow resistance resulting from feeding an adequate volume of water into the flow tube is considered. The polar parameters of water selected for analysis are different than oil. Experimental studies were not carried out in this regard, since the commonly accessible equation expressing the resistance of two-phase liquid–liquid flow was utilized to develop the method discussed in this study. On its basis, simulations were carried out to determine the conditions and level of reduction of the two-phase flow resistance in comparison to the single-phase flow resistance of a highly viscous oily liquid. The analysis of the results provided means for determination of such ranges of variations in the flow parameters of the two-phase liquid–liquid system, in which the total power of pumps applied to pump both liquids is smaller than the power of one pump feeding oil into the pipeline in the conditions of single-phase flow. Calculations were performed for selected constant mass flux densities of oil with various viscosities as well as for water. The proposed method can be applied in the procedure of optimization calculations for pipeline installations and their feed systems. The given example of its use was preceded by a description of the reasons and effects associated with the reduction of flow resistance in liquid–liquid systems and a detailed presentation of how to use the equation that forms the essence of the described calculation method. Attention was also paid to other phenomena accompanying two-phase liquid–liquid flows, i.e., interfacial slip, phase inversion, specific flow structures, and the viscosity of the unstable mixture of two liquids flowing in the pipe.
Highlights
The important and currently up-to-date steps aimed at rational energy use require optimization of technological installations in terms of energy demand, mainly electricity or heat
The drag resistance effect will result from selection of an adequately controlled flow rate of water fed into the oil flowing in the pipe, i.e., creation of specific conditions for two-phase liquid–liquid flow
On the basis of the description provided above, we can conclude that the drag reduction effect of a liquid two-phase water forms in oil oil (W/O) mixture can be achieved as a consequence of a simple increase of flow rate of the water phase characterized by low viscosity
Summary
The important and currently up-to-date steps aimed at rational energy use require optimization of technological installations in terms of energy demand, mainly electricity or heat. Experimental studies concerned with the flow of this type of two-phase liquid–liquid systems carried out on various scales demonstrate the effect of reducing the flow resistance of the highly viscous oil phase can be obtained by introducing a certain amount of water into the pipe, e.g., as described in study Mc Kibben et al [11,12]. A decrease in the flow resistance of a highly viscous substance can be caused by introducing a small amount of a gas phase into the pipe Such a method is of particular importance when permanent emulsion systems are pumped (in particular, ones classified as O/W type). The drag resistance effect will result from selection of an adequately controlled flow rate of water fed into the oil flowing in the pipe, i.e., creation of specific conditions for two-phase liquid–liquid flow
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