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Sand Separator Flow Analysis

Custom Process Equipment P.O.: 000964-12015

KnightHawk Project: CPE0120313

Report #: CPE0120313-01

Prepared For:

Brandon Gaspard

Custom Process Equipment, LLC4727 NW Evangeline Thruway

Carencro, LA 70520

By:D. Lee Hill, PhD.

Sandra XiaSrikanth Pathapati, PhDCliff

Digitally signed by Cliff Knight

DN: cn=Cliff Knight, o,

ou=KnightHawk Engineering,

Inc.,

email cknight@knighthawk co




Table of Contents

Table of Contents ........................................................................................................................... i Figures ........................................................................................................................................... i

Tables ............................................................................................................................................ i Introduction ................................................................................................................................... 1

Scope ............................................................................................................................................ 1

Assumptions ................................................................................................................................. 2

Equipment Description .................................................................................................................. 2

Flow Analyses ............................................................................................................................... 2

MODEL DEVELOPMENT ................................................................................................................ 2

G AS, LIQUID AND SOLIDS RESULTS ............................................................................................ 10

Conclusions ................................................................................................................................ 16

Recommendations ...................................................................................................................... 16

APPENDIX A: Client Information ............................................................................................ A - 1

EMAIL INFORMATION ............................................................................................................... A - 1

S AND SEPARATOR DRAWING .................................................................................................. A - 2

Figures

FIGURE 1: S AND SEPARATOR CFD MODEL ..................................................................................... 4

FIGURE 2: COMPUTATIONAL MESH – INLET REGION ......................................................................... 6

FIGURE 3: COMPUTATIONAL MESH – TOP REGION ............................................................................ 7

FIGURE 4: COMPUTATIONAL MESH – CENTER PIPE REGION ............................................................. 8

FIGURE 5: ABSOLUTE PRESSURE DISTRIBUTION (PSI). ................................................................... 11

FIGURE 6: G AS P ATHLINE DISTRIBUTION ....................................................................................... 12

FIGURE 7: LIQUID P ATHLINE DISTRIBUTION .................................................................................... 13

FIGURE 8: S AND P ARTICLE P ATHLINES, D = 0.0166 IN (VELOCITY, FT/S). ........................................ 14

FIGURE 9: S AND P ARTICLE P ATHLINES, D = 0.00166 IN (VELOCITY, FT/S). ...................................... 15

Tables

T ABLE 1: BOUNDARY CONDITIONS ............................................................................................... 10

T ABLE 2: FLOW ANALYSIS RESULTS SUMMARY ............................................................................. 10




Introduction

Custom Process Equipment, LLC (CPE) manufactures a wide range of custom processequipment packages. They have a Sand Separator design that takes in multiphase flows (gas,liquids and sand) and separates out the sand. They require a Computational Fluid Dynamic(CFD) analysis on the design to estimate the efficiency (percent of sand removal) of theequipment design.

KnightHawk Engineering, Inc (KHE) has been contracted to perform the required CFD analysison the Sand Separator.

Scope

KHE performed the following scope items to achieve the goals and objectives of this project:

1. Flow Analysis: KHE developed a computational fluid dynamics (CFD) model from thedrawing and information provided by CPE. One analysis was run total, with a pressurecondition of 4000 psi analyzed for the following flow condition. All models and analyseswere developed and executed in accordance with KHE practices and based on KHEexperience with this type analysis. Definition, design, and boundary conditions weredetermined by KHE based on the data provided by CPE.

1.1. Gas, Liquids & Solids Analysis: This analysis consisted of establishing a steadystate flow analysis with gas & liquid only. Once the analysis was stable, the flow wasseeded with a volume of fixed particle sized solids (defined by CPE.) The particulatepath and separation efficiency were evaluated.

2. Reporting: This certified report was developed under the supervision of a registeredprofessional engineer.




Assumptions

The following assumptions were defined for the analysis work presented in this report:

1. Validity of any engineering calculations depends upon, and is limited to, the accuracyand completeness of data CPE provided to KHE.

2. In developing this report, KHE assumes that the responsible facility’s operation andmaintenance of subject equipment and interconnecting equipment is in accordance withgenerally accepted industry standards and that all related equipment is designed andinstalled in accordance with applicable codes and standards.

3. The in-service condition of the equipment modeled matches the drawing provided unlessotherwise stated or indicted.

Equipment Description

Drawings provided by CPE for the Sand Separator design analyzed in this project are attachedto the appendix of this report.

Flow Analyses

Model Development

Using the drawing provided by CPE, a computational solid model was developed of the sandseparator as shown in Figure 1. . The model developed shows that the flow enters through the

inlet at the side of the vessel near the top. The multiphase flow mixture then swirls downwardalong the outer diameter. Once the bottom is reached, the flow changes direction and spiralsupward along the center region where it enters into one of 3 slots in a pipe. From there the flowleaves the vessel and proceeds to the downstream chokes. It is gravity that prohibits the heavierparticulate from traveling upward and out of the vessel.

A hybrid computational mesh was developed using this model. The inlet pipe region is shown in




to the inlet plane. At the exit plane, pressure (4013 psig) is applied and all other quantities are

extrapolated from inside the flow domain. The turbulence model used is the realizable k- model.

Particle tracking is implemented on a Lagrangian basis which essentially uses a first principlesapproach to predict how a particle of a given size and distribution interacts with the otherphases. Turbulence modeling for this part of the calculation uses a random walk model tosimulate spurious turbulent bursts.

CPE provided KHE with the information required to define the fluid components. The specificgravity of the gas was given as 0.65. The specific gravity of the fluid was given as 1.03. and thesolid particles are made up of sand (s.g = 2.65 was used). Due to the small variations in density,the resulting solution is based on steady state incompressible flow. Once the gas/fluid mixture

flow field is calculated, sand particles are then seeded to determine how much stays in thevessel. The ratio of how much stayed divided by the total amount seeded represents theefficiency.




KnightHawk Engineering, Inc. KHE Project #: CPE0120313March 29, 2012 Page 4

Figure 1: Sand Separator CFD Model





Internal Dome

3

slots

120° apart

Inlet

Exit





Figure 2: Computational Mesh – Inlet Region





Figure 3: Computational Mesh – Top region





Figure 4: Computational Mesh – Center Pipe Region








Gas, Liquid and Solids Results

KHE analyzed the performance of the sand separator run under the flow conditions specified inTable 1. Figure 5 shows contour plots of the static pressure on a center perpendicular placeacross the height of the separator. The pressure distribution in the separator changes withheight due to the effect of the density of the fluids, as expected. The pressure distribution in thecenter pipe remains fairly constant.

The pathlines of the gas and water are shown in Figure 6 and Figure 7 respectively. These

figures provide means for understanding the flow path.

Sand particle tracks for a diameter of 0.0166 in are shown in Figure 8 and are colored byvelocity. 99 % of sand particles were separated. KHE analyzed separation of a range of particlediameters down to a tenth of the given diameter of 0.0106 in. The lowest separation efficiencywas 90.8 %, for a diameter of 0.00166 in. Figure 9 depicts sand particle tracks for a diameter of0.00166 in. The results of these calculations are shown in Table 2.

Table 1: Boundary Conditions

Gas Flow Rate (mscfd) 12

Gas S.G1 0.65

Operating Pressure (psig) 4,000

Gas Temperature (F) 100

Liquid Flow Rate (bbl/hr) 200

Liquid S.G2 1.03

Sand Flow Rate (lbs/day) 2,000

Sand Particle Diameter(in) 0.0166Sand S.G 2.65

1.Gas specific gravity is calculated relative to the density of air.2.Liquid specific gravity is calculated relative to the density of water

Table 2: Flow Analysis Results Summary

Diameter(in)

Efficiency(%)

0.0166 99.9

0.008 99.9

0.006 99.9

0.003 99.7

0.0022 96.9





Figure 5: Absolute Pressure Distribution (psi).





Figure 6: Gas Pathline Distribution

Red – Inner

Vortex

Blue

– Outer

Vortex





Figure 7: Liquid Pathline Distribution

Red – Inner

Blue –





Figure 8: Sand Partic le Pathlines, D = 0.0166 in (velocit y, ft/s).





Figure 9: Sand Partic le Pathlines, D = 0.00166 in (veloc ity, ft /s).




Conclusions

The work performed indicates that the efficiency for containing the sand particulate is 99.9 % fora sand particle diameter of 0.0166” (mesh no. 40). KHE also found that the efficiency will belowered if the particle size is smaller.

Recommendations

1. KHE recommends that the impact of sand accumulation on vessel efficiency bedetermined.

2. The vertical structure of the predicted gas/liquid flow field should be investigated todetermine the impact of local transient behavior which could influence separationefficiency.

3. A sufficient mechanical analysis should be performed to ensure the mechanical integrityof the vessel by a competent engineer.

Note: KHE reserves the right to modify or change any opinions based on any new data orinformation obtained and any ongoing work in progress relevant to this project.

Respectfully submitted, Approved,

Lee Hill

D. Lee Hill, PhD. Cliff Knight, PESpecialty Engineering Group President & Chief EngineerKnightHawk Engineering, Inc.LA Registration – 21425LA Firm Registration – C 3101




APPENDIX A: Cl ient Information

Email Information

From: Brandon Gaspard [mailto:[email protected]]Sent: Tuesday, March 13, 2012 10:52 AMTo: [email protected]

Subject: CPE CFD Study

Kevin here is the information required for the study;

12 mmscfd Gas (SG .65)

200 BBL/Hr Liquids (SG 1.03 Produced Water)

2000lbs/ Day Sand 40 Mesh Dia .0166

100 Deg F

4,000 PSIG

Use existing 20"x8' design

Please let me know if the attached file will import properly. If not let me know what file type will work.

Brandon Gaspard

Custom Process Equipment, LLC.

Business Development Mgr.

Office +1.337.896.3815

Mobile +1.337.278.9431

[email protected] www.cpe-llc.com

skype: brandon.gaspardskype: +1.337.366.8223




KnightHawk Engineering, Inc. KHE Project #: CPE0120313March 29, 2012 Page A – 2

Sand Separator Drawing

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