Simulated Flow Through Structured Packing Mike Basden Bruce - - PowerPoint PPT Presentation

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Simulated Flow Through Structured Packing Mike Basden Bruce - - PowerPoint PPT Presentation

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Simulated Flow Through Structured Packing Mike Basden Bruce Eldridge The University of Texas at Austin Structured Packing Used in distillation, absorption, and stripping High efficiency, low pressure drop, and high capacity Single

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SLIDE 1

Simulated Flow Through Structured Packing

Mike Basden Bruce Eldridge The University of Texas at Austin

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SLIDE 2

Structured Packing

  • Used in distillation, absorption, and stripping
  • High efficiency, low pressure drop, and high

capacity

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SLIDE 3

Single Phase Simulations

  • Experimental Validation

– Simulation and experimental bed were nearly identical

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SLIDE 4

k-ε = 20.74*F1.7537 k-ω = 20.118*F1.7307 EXP = 23.944*F1.7464 20 40 60 80 100 120 140 160 180 0.5 1 1.5 2 2.5 3 3.5

Total Bed Pressure Drop (Pa) F-factor (Pa0.5)

Comparison to Experimental Data

k-ε k-ω EXP

F = vgρg

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SLIDE 5

Packing Design Simulations

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SLIDE 6

Packing Dimensions

h θ b

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SLIDE 7

α = 45°, ap = 250 m2/m3, UGS= 1 m/s, Nitrogen Flow

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SLIDE 8

Multiphase Simulations

  • Effect of simulation contact angle, liquid

density, surface tension, and liquid viscosity examined on periodic geometry

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SLIDE 9

Contact Angle Definition

Starov, V. M.; Velarde, M. G.; Radke, C. J. Wetting and Spreading Dynamics; CRC Press: Boca Raton, 2007.

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SLIDE 10

Contact Angle = 75°

hL = 6.5%

0.074 N/m af = 0.27 L= 39 GPM/ft2 0.037 N/m af = 0.30 L= 46 GPM/ft2 0.018 N/m af = 0.35 L= 47 GPM/ft2

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SLIDE 11

Contact Angle = 30°

hL = 6.0%

0.074 N/m af = 0.48 L= 22 GPM/ft2 0.037 N/m af = 0.65 L= 20 GPM/ft2 0.018 N/m af = 0.80 L= 21 GPM/ft2

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SLIDE 12

Contact Angle = 0°

hL = 6.5%

0.074 N/m af = 0.80 L= 19 GPM/ft2 0.037 N/m af = 0.97 L= 19 GPM/ft2 0.018 N/m af = 0.98 L= 23 GPM/ft2

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SLIDE 13

Impact of Liquid Density

θc =30°, hL = 6.5%, σ = 0.074 N/m

af = 0.281 L= 24 GPM/ft2 ρ= 500 kg/m3 af = 0.48 L= 23 GPM/ft2 ρ= 997 kg/m3 af = 0.58 L= 23 GPM/ft2 ρ= 1500 kg/m3

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SLIDE 14

Impact of Viscosity

θc =30°, σ = 0.018 N/m, ρ=997.561 kg/m3

μL=0.01774 Pa-s hL=6.7% af = 0.68 L= 2.4 GPM/ft2 μL=0.0008871 Pa-s hL=5.9% af = 0.80 L= 20.9 GPM/ft2

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SLIDE 15

Experimental Validation

  • Wetted area measurements performed

via absorption of CO2 into dilute caustic solution

  • 10 ft. bed of Mellapak N250.Y
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SLIDE 16

Wetted Area – Experimental Measurements

20 40 60 80 0.2 0.4 0.6 0.8 1 1.2 10 20 30 m3/m2-hr Fractional Wetted Area Liquid Load (GPM/ft2) 20 ACFM 40 ACFM Start of Run 60 ACFM Tsai Correlation 0.61 Pa0.5 1.22 Pa0.5 1.83 Pa0.5

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SLIDE 17

Multiphase Simulations – CT Geometry

Liquid Velocity Inlet Pressure Boundary Condition

  • Calculate fractional

wetted area and holdup for indicated element

– af = aw/ap – hL – ΔPIrrigated

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SLIDE 18

X-ray CT / CFD Comparison

  • C. W. Green, J. Farone, J. K. Briley, R. B. Eldridge, R. A. Ketcham, B. Nightingale, “Novel Application of X-ray

Computed Tomography: Determination of Gas/Liquid Contact Area and Liquid Hold-up in Structured Packing,”

  • Ind. Eng. Chem. Res., (46) pg. 5734-5753, 2007.

0.074 N/m af = 0.89 L = 15 GPM/ft2 0.074 N/m af = 0.85 L = 15 GPM/ft2

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SLIDE 19

L=20 GPM/ft2

θc = 0°, af=0.91 θc = 30°, af=0.67

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SLIDE 20

Fractional Wetted Area

af = 0.718L0.080 R² = 0.978 af = 0.323L0.245 R² = 1 af= 0.609L0.1547 R² = 1

20 40 60 0.0 0.2 0.4 0.6 0.8 1.0 1.2 5 10 15 20 25

(m3/m2-hr) Fractional Wetted Area Liquid Load (GPM/ft2) CFD Sim, θ=0° CFD Sim, θ=30° Tsai Model

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SLIDE 21

Fractional Liquid Holdup

20 40 60 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 5 10 15 20 25 m3/m2-hr Liquid Holdup (%) Liquid Load (GPM/ft2) CFD Sim, θ=30° CFD Sim, θ=0° Experimental

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SLIDE 22

Irrigated Pressure Drop

Contact Angle Liquid Load F-factor CFD Pressure Drop Experimental Pressure Drop Percent Error ° GPM/ft2 Pa0.5 Pa/m Pa/m 10 0.86 74.7 52.0 43.5% 15 0.77 74.4 52.1 42.7% 20 0.69 73.4 58.8 24.8% 30 10 0.82 73.1 47.6 53.6% 30 15 0.73 71.4 46.7 52.8% 30 20 0.66 73.5 54.1 35.8%

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SLIDE 23

Conclusions

  • Single phase simulations can predict trends and

pressure drops accurately

  • Multiphase simulations require further analysis

– Experimentally determined static contact angle not appropriate for predicting wetting – Liquid holdup and irrigated pressure drop need additional corrections:

  • Damping of the turbulence at the interface
  • Viscosity correction
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SLIDE 24

Acknowledgements

  • CD-adapco
  • Mark Pilling and Sulzer Chemtech
  • Texas Advanced Computing Center
  • UT High Resolution CT Lab
  • Process Science and Technology Center
  • Lummus Technology
  • Christian Waas and Shawn Grush
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SLIDE 25

Questions?

  • Mike Basden

– mbasden@utexas.edu

  • Bruce Eldridge

– eldridge@che.utexas.edu