Generation of frictional DRA in petroleum pipelines and the method of drag reduction sing high density polymers

1. Frictional Drag Reduction
in Pipelines using High
Density Polymers
Pawan Kumar
16 ME62 R07

2. Typical Petroleum Transportation
network
Source-David Wood & DWA Energy Limited
http://www.dwasolutions.com/DWA/DWTrainingOptions.ht
m

3. India’s Oil Market

4. Flow Through a Pipe
The length of the hydrodynamic entry region along the pipe is called
hydrodynamic entry length. It is a function of Reynolds No. (Re) of the flow.
L for Laminar Flow= 0.05 Re X D
L for turbulent Flow= 1.359 DX (Re)^0.25

5. Flow Through a Pipe
• Can be classified as either Laminar or Turbulent.
• For Reynolds number less than 2300, laminar and
above that turbulent
• More energy is wasted in turbulent flow due to
generation of eddies

6. Drag Generation in a Pipe Flow
• Drag generated in a pipeline is the loss of
pressure or “head” that occurs due to the effect
of the fluid's viscosity near the surface of the
pipe or duct
*For a real fluid pressure at point 2 shall always be less than pressure at point 1

7. Boundary Layer in a typical pipe
flow

8. Calculation of Frictional Drag
generated in a pipe flow
• Loss in pressure due to Friction (Darcy–
Weisbach equation)
h-head loss due to friction (mcl)
L-Length of pipe section
v-average flow velocity
d-hydraulic diameter of pipe section
g-acceleration due to gravity
f-coefficient of friction

9. Calculation of Frictional Drag
generated in a pipe flow
• Coefficient of friction (f) in the Darcy–Weisbach
equation is different for Laminar and Turbulent
flows
• For Laminar Flow
Re is the Reynolds number for the flow
• For Turbulent Flow, empirical relations are used
for the calculation of coefficient of friction. Most
notables are given below
Re
64
=f

10. Calculation of friction factor (f) for
Turbulent flow inside a pipe

11. Calculation of friction factor (f) for
Turbulent flow inside a pipe
• A more general equation for calculating “f” for
turbulent flow in both smooth and rough pipes
was given by Colebrook and White.
• The equation being implicit in nature, has to be
solved by iteration.
• For most of the purposes, Moody Chart, which is
a graphical representation of “f” and “Re” is used

13. Loss in Pressure due to friction
• Pipe size- 22 inches
• Viscosity of fluid-25 cst
• Density of fluid- 860 kg/m3
Flow rate in
m3/hr. 500 600 700 800 900 1000 1100 1200 1300 1400 1500
Loss in
Pressure (Kpa)
per km 8.21 11.27 14.73 18.59 22.83 27.45 32.44 37.78 43.48 49.53 55.93

14. DRA
• Drag reducing agent (DRA) are the class of chemicals that
reduces frictional losses during fluid flow in a conduit or pipeline

15. Why use DRA
• To decrease the operating pressure of a
Pipeline, keeping the same flow rate
• To increase the flow rate, keeping the same
operating pressure
• To reduce the energy consumed by prime
movers (Engine, Electric Motor etc.)
• To meet peak/ seasonal demands with the
existing system

16. Mechanism of DRA
• Drag reduction phenomenon first reported by
British chemist Toms in 1948
• Long chain polymers interact with fluid
molecules that reduces formation of turbulent
eddies

17. Mechanism of DRA
• Ultra high molecular weight, long chain
hydrocarbon polymers suspended in solvent
Polyalpha-olefins (PAO)
Flow in a pipeline without DRA Flow in a pipeline with DRA

18. Mechanism of DRA
• On contact it forms long chains of polymer.
• Long polymer chains acts as elastic conduits avoiding the flow
in radial direction.
• Polymers tend to stretch in the flow and absorb the energy in
the streak, which in turn stops the burst that produces the
turbulence in the core and results in a reduction in turbulence.

19. DRA
Reduction in radial velocity component of fluid particles results in
less momentum transfer with the pipe wall and hence less
pressure and also an increase in the flow rate

20. Effectiveness of DRA
Drag Reduction (DR)
•Effectiveness of DRA is ascertained from Drag
Reduction (DR) obtained
• ∆Po is pressure drop of untreated liquid
• ∆Pd is pressure drop of liquid doped with DRA

21. Effectiveness of DRA
• Based on Experimental data, drag
reduction is related to the thermo physical
properties of the fluid, dimensions of the
conduit and the concentration of the drag
reducing chemical as given under
Where, -Absolute roughness of pipe surface in inches
• d- Internal diameter of pipe in inches
• Re- Reynolds number
• ppm- injection rate of DRA chemical in ppm
kakb
(ppm)/d)((L/d)M(Re)=%Dr ∈
∈

22. Effectiveness of DRA
As can be seen from the above, the percentage reduction in pressure
loss due to friction sharply increases with the concentration of Drag
Reducing Agent (a surfactant in this case) being injected in the pipeline
Source:- Ali A. Abdul-Hadi and Anees A. Khadom, “Studying the Effect of Some Surfactants on Drag Reduction of
Crude Oil Flow,” Chinese Journal of Engineering
Volume 2013

23. Thanks