Pharmaceuticals & Biotechnology

Chemistry & Metallurgy

Oil & Gas

CFD designed internals for Produced Water Tanks

Dr. Eng. Eduard Sarbu

Outline

1. Introduction

2. Case Study – existing PWT

3. Pilot Tank

• concept and results

4. Improvements

• concept, results and applications

5. Conclusions

1. IntroductionProduced Water Tanks (PWTs) and Phase Separation

• PWTs used as

− 1st stage separators

− buffer tanks

− storage volume

• Simple design with few or no

internals

• Stoke’s law for gravity separation:

𝒗𝒔 =𝒅𝒅𝟐 × (𝝆𝒘 − 𝝆𝟎)

𝟏𝟖 × 𝜼𝟎

• larger diameters, greater density

difference, higher temperatures

→ faster separation

• for better phase separation

→ maximize residence time

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2. Case study Existing PWT

Old Pilot Tank Design and Residence Time Distribution (RTD)

Original tank design with single change in flow direction

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3. Pilot TankConcept

Tangential Flow Pattern

Tangential injection of oil – water phase via diverter; central outlet pipes

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3. Pilot TankResults

CFD Simulation and Tracer Test Results

• CFD model used to perform virtual

tracer test

• Tracer test for new tank internals

• Sufficient consistency between real

tank and CFD model

• RTD increased by factor 8

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3. Pilot TankResults

Completed Internals

Oil in water (OIW) concentration reduced from 1000 ppm to 250 ppm

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4. ImprovementsConcept

Symmetrical internals

• 2 inlet diverters, 1 central outlet • Internals design based on tank geometry

Inlet 1

Inlet 2

Outlet

Inlet 1

Inlet 2

Outlet

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4. ImprovementsResults

Flow Pattern for Symmetrical Arrangement

No short circuits and low flow velocities in cm/sec

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4. ImprovementsResults

RTD for Symmetrical Setup

CFD Tracer Test Results for Symmetrical Internals

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4. ImprovementsApplications

Additional Applications for PWT CFD Models

Predict separation efficiencies and outlet concentrations

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5. Conclusions

• Symmetrical tangential flow patterns improve PWT performance

• CFD optimized internals reduce velocities and short circuiting

• Optimal use of tank volume, less mixing, better coalescence

• Tailor-made solutions based on CFD models

• Reduces overall number of separation stages/equipment

• Reduces plant footprint and total CAPEX

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Contact data

• Eduard Sarbu, eduard.Sarbu@vtu.com (+40731 336 537)

Acknowledgements:Nikolas Trofaier, VTUBernhard Puchner, VTUJaroslaw Konieczny, VTUAnne Steinbrugger, VTU Alexander Weilhartner, OMVGeorg Kuemmel, OMV Oscar Perez, OMV PetromNikolaus Friedl, CAERichard Markl, CAE

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