ORIGINAL PAPER
Numerical modeling of a hydrocyclone for the separation of oil residues in offshore installations
 
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1
Kirkuk Technical Engineering College, Northern Technical University, Iraq
 
2
Northern Technical University, Renewable Energy Research Center-Kirkuk, Iraq
 
3
Imam Ja'afar Al-Sadiq University, Iraq
 
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University of Kirkuk, Iraq
 
 
Submission date: 2025-09-05
 
 
Final revision date: 2025-10-01
 
 
Acceptance date: 2025-10-09
 
 
Publication date: 2026-06-29
 
 
Corresponding author
Mustafa Naozad Taifor   

Kirkuk Technical Engineering College, Northern Technical University, 36001, Kirkuk, Iraq
 
 
Polityka Energetyczna – Energy Policy Journal 2026;29(2):33-58
 
KEYWORDS
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ABSTRACT
This study numerically investigates oil–water separation in a hydrocyclone using the Hsieh design, selected for its manufacturability and proven experimental database. Computational Fluid Dynamics (CFD) simulations were conducted in ANSYS Fluent 16.1 employing an Eulerian–Lagrangian framework, where the water phase was resolved with the Reynolds Stress Model (RSM) and oil droplets were tracked through the Discrete Phase Model (DPM) under one-way coupling. A mesh independence study confirmed solution stability at 3.16 million cells, and residual convergence was achieved after approximately 1600 iterations, ensuring accurate predictions of velocity, pressure, and air core formation. The numerical results successfully reproduced the characteristic double-vortex flow, axial velocity reversal, and negative static pressure region responsible for air core development, showing strong agreement with published experimental data. Particle tracking demonstrated that separation efficiency strongly depends on droplet size, increasing from approximately 80% for fine droplets (1–5 µm) to a maximum of nearly 90% for larger droplets (≥75 µm), resulting in an overall efficiency close to 90%. However, a fraction of water was entrained in the overflow, revealing design limitations that could be mitigated by modifying the vortex finder or underflow geometries. The validated model provides a robust framework for optimizing hydrocyclone geometry and operating conditions, contributing to enhanced oil–water separation efficiency, reduced water discharge, and improved environmental compliance in offshore production systems.
CONFLICT OF INTEREST
The Authors have no conflicts of interest to declare.
METADATA IN OTHER LANGUAGES:
Polish
Numeryczne modelowanie hydrocyklonu do separacji pozostałości olejowych w instalacjach morskich
separator hydrocyklonowy, separacja oleju od wody, model naprężeń Reynoldsa (RSM), model Hsieha, sedymentacja odśrodkowa
W niniejszym badaniu przeprowadzono numeryczną analizę procesu separacji oleju od wody w hydrocyklonie o konstrukcji Hsieha, wybranym ze względu na łatwość wykonania oraz sprawdzoną bazę danych eksperymentalnych. Symulacje dynamiki płynów (CFD) przeprowadzono w programie ANSYS Fluent 16.1 z wykorzystaniem modelu Eulera-Lagrange’a, w którym faza wodna została rozwiązana za pomocą modelu naprężeń Reynoldsa (RSM), a krople oleju śledzono za pomocą modelu fazy dyskretnej (DPM) w ramach sprzężenia jednokierunkowego. Badanie niezależności siatki potwierdziło stabilność rozwiązania przy 3,16 mln komórek, a zbieżność resztkowa została osiągnięta po około 1600 iteracjach, zapewniając dokładne prognozy prędkości, ciśnienia i tworzenia się rdzenia powietrznego. Wyniki numeryczne z powodzeniem odtworzyły charakterystyczny przepływ z podwójnym wirem, odwrócenie prędkości osiowej oraz obszar ujemnego ciśnienia statycznego odpowiedzialny za rozwój rdzenia powietrznego, wykazując silną zgodność z opublikowanymi danymi eksperymentalnymi. Śledzenie cząstek wykazało, że wydajność separacji silnie zależy od wielkości kropelek, wzrastając z około 80% dla drobnych kropelek (1–5 µm) do maksymalnie prawie 90% dla większych kropelek (≥75 µm), co daje ogólną wydajność bliską 90%. Jednak część wody została porwana w przepływie przelewowym, ujawniając ograniczenia konstrukcyjne, które można złagodzić poprzez modyfikację geometrii wzniesienia wirowego lub przepływu podwirowego. Zweryfikowany model stanowi solidną podstawę do optymalizacji geometrii hydrocyklonów i warunków ich pracy, przyczyniając się do zwiększenia wydajności separacji ropy od wody, zmniejszenia ilości odprowadzanej wody oraz poprawy zgodności z przepisami środowiskowymi w morskich systemach wydobywczych.
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