Numerical investigation of melting of waxy crude oil in an oil tank

Abstract

：A safe and economic waxy crude oil melting scheme is an important issue in oil tank storage, and thus a better understanding of the melting mechanism of waxy crude oil in the tank is necessary to develop a scientific scheme for melting. With the consideration of wax precipitation and non-Newtonian behavior, this paper establishes physical and mathematical models for melting process of waxy crude oil in the tank, and then develops an integrative numerical procedure for the coupling of physical process within wax crystal porous media, solid-liquid dispersion system and pure liquid waxy crude oil. In this research, the non-Newtonian behavior is described by the power-law equation. The melting process is simulated by the enthalpy-porous media theory. The melting characteristics of waxy crude oil in the tank with Pr=354.3, Ra=1.0×10 6 and Ste=0.371 is investigated. Particularly, the effects of wax precipitation and non-Newtonian behavior are analyzed in detail. The results show that, during melting, the heat flux varies at different stages under different wax precipitation scenarios. At the initial melting stage, heat flux decreases with the increase of the wax precipitation, and in the natural convection melting stage, heat flux increases with the increase of wax precipitation. The effect of non-Newtonian behavior on melting process is influenced by the permeability constant of wax crystal porous media. When the permeability constant is small, non-Newtonian behavior has little effect on the melting process. Conversely, when the permeability constant is large, strengthening the non-Newtonian behavior will slow down the melting process.

Coastal Shuttle Tanker Scheduling Model Considering Inventory Cost and System Reliability

“…This article uses constraint group 3 to match the voyage in K with the shuttle tanker. Equation (11) requires that each voyage can only be performed by one shuttle tanker. Equation 12is the constraint on decision variables .…”

“…Therefore, energy consumption is a significant factor in the operation cost for crude oil transfer and processing. Since the FPSOs are collecting crude oil from the oil platform, the oil stock quantity is continually changing, affecting the storage cost of crude oil [11]. The tanker for FPSO operates within a short distance and with high frequency making the transportation system vulnerable for the uncertainty of maritime transportation, such as weather conditions and port occupancy [12].…”

Thermal Analysis of Crude Oil in Floating Roof Tank Equipped with Horizontal Heating Finned Tube Bundles

“…[3,4] With the increasing demand for strategic crude oil reserves in China, floating roof tanks are being the preferred storage equipment for large-scale crude oil depots due to technical and economic advantages. [5][6][7][8] However, most of the crude oil produced in China is waxy crude oil, which has the characteristics of high viscosity and complex rheology. [9,10] There is a risk of gelatinization of waxy crude oil during static storage period when suffers from an extreme low ambient temperature.…”

Numerical simulation and analysis of phase change heat transfer in crude oil

“…Therefore, there is a liquid-solid mixed fuzzy zone in the process of phase transition in the pipeline, which can be regarded as porous medium. For this fuzzy region, most scholars used enthalpy -porous media model to describe heat transfer and flow [27][28][29][30]. In the above models, Darcy formula was used to describe the natural convection of liquid phase in the pores.…”