Sam Maurer

1
The Effect of Diameter on Polymer Degradation
During Turbulent Drag Reduction

• Sam Maurer

2
Outline

• Objective to measure the effect of pipeline
  diameter on degradation kinetics of drag-reducing
  polymers
• Background
• Since 1979, polymeric drag reducing agents (DRAs)
  used in over 100 commercial pipelines, such as
  the Trans-Alaska Pipeline System (TAPS)
• Degradation of polymers decreases drag reduction
  in all pipelines
• Approach
• Use a 4.57 mm inner diameter (ID) test pipe to
  model TAPS (1100 mm ID)
• Use measured pressure drops to calculate apparent
  first-order degradation rate constant in test
  pipe
• Compare to literature and previous 10.26 data
  using larger pipeline IDs
• Results
• Found kdeg 67 s-1, higher than previous value
  of 3.4 s-1 found for a 4.57 mm ID pipe (10.26
  Team 5 2005)
• However, found kdeg to vary 10 30 with
  concentration at any given pump setting,
  suggesting non-first-order kinetics
• Conclusions

3
Background Motivation

• 1948 BA Toms discovers dilute amounts of
  macromolecules added to solutions in turbulent
  flow decrease frictional losses
• 1977 TAPS first opened, transports oil 800
  miles
• 1979 Long-chain hydrocarbon DRAs introduced in
  TAPS

• 1982 Brostow suggests using DRAs to improve
  storm sewer capacity, fire hose flow rate
• 2006 DRAs used in over 100 industrial pipelines
  worldwide

Source TAPS website, www.alyeska-pipe.com/default
.asp
4
Background Theory

• In Newtonian flow, friction of fluid flowing past
  pipe wall causes pressure drop, requires energy
  expenditure
• With DRAs, pressure drop reduced at constant flow
  rate
• Limit of drag reduction is not laminar flow,
  rather Virks Maximum Drag Reduction asymptote
  (MDR)
• Possible mechanism polymeric DRAs suppress
  macroscale eddy formation by bridging turbulent
  bursts
• Longer DRAs affect superior drag reduction
• Coiled DRAs extended due to wall shear stress
• Drag reduction limited by scission of long-chain
  DRAs

5
Background Chemistry
Extension
2.Rgyration 600 nm
Contour Length 690000 nm
Degradation
Polymers undergo midpoint scission
Contour Length 345000 nm
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Background Previous Work
Phenomenon of Drag Reduction and Degradation
(Paterson 1970)
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Approach Current Work
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Approach Apparatus
DRAIN
Pressure Transducer
Multimeter Readout
Storage tank
Storage tank
-
P
Stand pipe
P
Gravity bypass
DRAIN
TAP 1
TAP 2
TAP 3
TAP 4
L/D 50 20 20 20
DRAIN
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Approach Prandtl-Karman Calculation
Pump Setting
Pressure Transducer
Flowrate V
Pressure Drop DP
10
Approach Kinetics Calculation
Slip S
Prandtl-Karman Plot for 2 ppm aqueous PEO solution
S 1/vf polymer 1 /vf water
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Approach Kinetics Calculation
Maximum Slip S
Slip Plot for 2 ppm aqueous PEO solution
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Approach Kinetics Calculation
Volumetric Flowrate
Plot S / S (ratio of slip to maximum slip)
against residence time for 2 ppm aqueous PEO
solution
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Approach Kinetics Calculation
Volumetric Flowrate
Plot S / S (ratio of slip to maximum slip)
against residence time for 2 ppm aqueous PEO
solution
Slope of line is apparent first-order degradation
rate constant at a given pump setting
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Approach Kinetics Calculation
Plot degradation constant against tw in region of
tw 40 (scale with TAPS)
Establish correlation log(kdeg) A . log(tw) B
Calculated A 1.14 log(kdeg) 1.14 .
log(tw) kdeg 401.14 67
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Results Degradation Constant
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Results Degradation Variation
Volumetric Flowrate
Degradation constant at any given pump setting
varies 10 30 across C0 0.2 ppm to C0 2.0
ppm Kinetics might not be first-order
17
Results Water Olympic Plots
When running distilled water, pressure drops
across each of three tap pairs found to be
approximately equal
Flaws in taps therefore unlikely
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Results Polymer Olympic Plots
Voltage a Pressure Drop Indeed see drag
reduction, and degradation as we travel down the
pipe
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Results Reproducibility
Plotted on Prandtl-Karman coordinates, data from
different runs at the same polymer concentration
appear to be reproducible
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Conclusions

• Calculated kdeg 67 s-1 is 1 order of magnitude
  larger than kdeg 3.4 s-1 calculated by 10.26
  Team 5
• Using same apparatus
• Olympic plots show that taps do not appear to be
  flawed
• Data shown to be reproducible

21
Acknowledgements

• Team Members Jacqueline Brazin
• Stephanie Lee
• Team Advisor Prof. Preetinder S. Virk

22
Acknowledgements

• Team Members Jacqueline Brazin
• Stephanie Lee
• Team Advisor Prof. Preetinder S. Virk