scholarly journals A CFD study on hydrocarbon mean residence time in a horizontal oil–water separator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Tathagata Acharya ◽  
Terry Potter

AbstractThis study presents computational fluid dynamics analyses on oil–water flow characteristics in a horizontal separator. The performance of these vessels are inferred from mean residence time and cumulative residence time distribution of the hydrocarbon phase inside the separator. The authors model a separator used by previous researchers and evaluate mean residence time of the hydrocarbon phase in a two-phase mixture of oil and water. Three different water-cuts of 21%, 32%, and 57% are used. Additional analyses are done to assess how certain geometric features of the separator influence hydrocarbon mean residence time. The results show that the addition of a second perforated baffle plate does not improve the hydrocarbon mean residence time significantly. However, introducing a downward slanting throat section between the primary zone and the gravity separation zone improves the hydrocarbon mean residence time at 21% and 32% water-cuts. The results suggest oil–water separators with a throat section may be more efficient than regular horizontal separators without the throat section at low water-cuts.

Author(s):  
Terry Potter ◽  
Tathagata Acharya

Abstract Multiphase separators on production platforms are among the first equipment through which well fluids flow. Based on functionality, multiphase separators can either be two-phase that separate oil from water, or three-phase that separate oil, natural gas, and water. Separator performances are often evaluated using mean residence time (MRT) of the hydrocarbon phase. MRT is defined as the amount of time a given phase stays inside the separator. On field, operators usually measure MRT as the ratio of active volume occupied by each phase to the phase volumetric flowrate. However, this method may involve significant errors as the oil-water interface height is obtained using level controllers and the volume occupied by each phase is calculated assuming the interface can be extrapolated from the weir back to the separator inlet. In this study, authors perform computational fluid dynamics (CFD) on a two-phase horizontal separator to evaluate MRT as a function of varying water volume flowrates (water-cut) in a mixture of water and oil. The authors use residence time distributions (RTD) to obtain MRT at each water-cut — a method that results in significantly more accurate results than the regular method used by operators. The numerical model is developed with commercial software package ANSYS Fluent. The code uses the Eulerian multiphase model along with the k-ε turbulence model. The simulation results show agreement with experiments performed by previous researchers. Additional simulations are performed to assess the effect of various separator internals on separator performance. Simulation results suggest that the model developed in this study can be used to predict performances of two-phase liquid-liquid separators with reasonable accuracy and will be useful towards their design to improve performances under various inlet flow conditions.


2020 ◽  
Vol 159 ◽  
pp. 215-224 ◽  
Author(s):  
Sen Li ◽  
Ruoning Li ◽  
Franck C.G.A. Nicolleau ◽  
Zunce Wang ◽  
Yuejuan Yan ◽  
...  

2016 ◽  
Vol 19 (4) ◽  
pp. 48-53 ◽  
Author(s):  
Byeong Jun Kim ◽  
Sung Yoon Kim ◽  
Chun Su Roh ◽  
Young Ho Lee

Equipment ◽  
2006 ◽  
Author(s):  
Marijus Seporaitis ◽  
S. Gasiunas ◽  
Raimondas Pabarcius

2017 ◽  
pp. 144-150
Author(s):  
Peter W. Rein ◽  
M. Getaz ◽  
A. Raghunandan ◽  
N. du Pleissis ◽  
H. Saleh ◽  
...  

A new design for syrup and juice clarifiers is presented. The design takes advantage of the considerably improved performance of clarifiers incorporating lamella plates, and the reasons for the improvement are outlined. Computational fluid dynamics (CFD) work done to simulate the performance is summarised. This design enables the residence time to be dramatically reduced and the simplified design leads to cheaper and better clarifiers. Practical experience with factory scale units is described, confirming the good flow characteristics. The results of preliminary test work on a factory syrup clarifier are presented, which is also shown to operate efficiently as a phosphatation clarifier. In addition the performance of a full-scale juice clarifier has been evaluated and compared with the performance of a Rapidorr clarifier. This work confirms the considerable advantages which this type of design provides, in realising substantial reductions in residence time, capital costs and operating costs.


1982 ◽  
Vol 47 (12) ◽  
pp. 3362-3370
Author(s):  
Otakar Söhnel ◽  
Eva Matějčková

Filtration properties of batchwise precipitated suspensions of Zn(OH)2, Mg(OH)2 and Cu(OH)2 and continuously precipitated Al(OH)3 were studied. For batchwise precipitated suspensions was verified the theoretically predicted dependence of specific filtration resistance on initial supersaturation and for the continuously precipitated Al(OH)3 the relation between the specific filtration resistance and the mean residence time of suspension in the reactor. Dependences were also recorded between the bed porosity and concentration of precipitated solutions, specific filtration resistance and used filtration pressure and the effect of aging of the batchwise precipitated suspension of Mg(OH)2on its filtration properties. The used CST method for determination of filtration characteristics of Zn(OH)2 suspension was also studied.


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