With many of today's oil wells located offshore, the production of high volumes of water compared to oil poses major challenges to oil operators. The use of liquid-liquid hydrocyclone (LLHC) is one effective way to arrest these uphill problems of produced water. However, the nature of fluid flow within the LLHC device is very vital to the separation process and performance. This study through numerical simulation lends understanding to the way oil-water fluid migrates within LLHC device and shows how the flow structure can affect the efficiency of the separation process. Unsteady wavering flow was realized for the use of the single inlet due to flow imbalance just after entry into the cyclone. This affected the efficiency of separation as water droplets in the vicinity of the reverse flow core boundary could be carried to the overflow. In addition, there was the realization of frequent recirculation zones which cause some fluid droplets to be unseparated. Uniform unwavering fluid flow structure was observed in the case of dual inlet LLHC which assisted in the segregation of the oil and water into their respective core regions as oil-rich core (inner) and water-rich core (outer). The separation efficiency achieved from the use of the dual inlet LLHC outperformed that from the single inlet LLHC. An efficiency of 82.3% was obtained for the dual inlet LLHC as against 73.7% for the single inlet LLHC at 0.5 m 3 /h. At 1.0 m 3 /h, a great separation performance of 93.6% was achieved from the dual inlet LLHC, whereas separation efficiency of 88.5% was obtained when the same feed was treated in the single inlet LLHC.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Vane angle configuration is considerably affecting the internal flow behavior and separation performance of a concurrent axial inlet liquid–liquid hydrocyclone. This study was carried out to improve the design of the swirl generator by optimizing the vane’s deflection angle in an oil/water axial inlet hydrocyclone separator. Angles ranging from 37° to 75° were examined at various operational conditions, including mixture temperature, mixture flow rate, and water-to-oil ratio. Two analysis techniques have been coupled to achieve the aim. First, design of experiment by the response surface method was utilized to generate a combination of run/boundary conditions of swirler vane angles, inlet mixture temperatures, flow rates, and concentrations. The obtained 15 run/boundary conditions were adopted as cases for computational fluid dynamics simulation to determine the separation efficiency, tangential velocity and pressure drop of each case using ANSYS Fluent software. The optimization results show that the swirl generator with a 45° deflection angle generated slightly higher tangential velocity compared with higher and lower vane deflection angles. The separation efficiency obtained by using the 45° swirl generator was higher than other angles, in spite that the turbulence intensity is slightly higher at 45° compared to other vane angles.
Before being fed into the separators, a pump is often used to maintain adequate flowing pressure of oil/ water emulsion in a production conduit, especially in a depleted or matured reservoir. Droplet shearing and size reduction due to the pump highly affect the separation performance. This paper aims to present an experimental investigation on the shearing of oil droplets in an oil/water production fluid passing through a high rpm single-stage centrifugal pump (C-pump) and a lower rpm gear pump. A cross polarizer microscope has achieved sample analyses. The experiments have been carried out at various water/oil ratios, from 70/30 to 90/10, with two different temperatures of 50 o C and 80 o C. Further, the viscosities of the fluid sample from both pump outlets are correlated with the water cuts. The results are presented in a graphical format showing the droplet size distributions of different cases from the two tested pump types. There is a general trend of higher shear intensity and smaller mean oil droplets with the C-pump than the gear pump. Water cut and the temperature seem to have a small effect on the shearing of the droplets. Further, the viscosity correlation for the fluid collected from two pump outlets at different temperatures and water cuts shows a slight decrease in viscosity with the shear rate. However, it is highly affected by the water cut and temperature.
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