prediction of the separation efficiency of a 10 mm hydrocyclone using light liquid phase particles...
TRANSCRIPT
Prediction of the Separation Efficiency of Prediction of the Separation Efficiency of a 10 Mm Hydrocyclone Using Light a 10 Mm Hydrocyclone Using Light
Liquid Phase Particles Liquid Phase Particles
S. Austin, J. Williams, S. Smith and G. D. WessonDepartment of Chemical Engineering
FAMU-FSU College of EngineeringTallahassee, FL 32310
Presented at: 8th Annual International Petroleum and Environmental Conference
Houston, TXNovember 6-9, 2001
Presentation OutlinePresentation Outline• Motivation
• Hydrocyclone principles
• Particle separation theory
• Hydrocyclone performance measurements
• Separation experiments
• Results
• Conclusions and future work
• Acknowledgements
MotivationMotivationOil production
requires water treatment.
Required offshore constraint < 30 ppm of oil in water to environment
• Interest in down-hole separation
Hydrocyclone Operation PrinciplesHydrocyclone Operation Principles
• Tangential feed entry• Creation of core
vortex • High local
accelerations• Complex internal
flows• No moving parts
Liquid Particle -Fluid InteractionLiquid Particle -Fluid Interaction
• Liquid particles remain spherical• Particle diameter < 50 microns
• Rep <0.1 , i.e. creeping flow
• Incompressible fluids
Liquid Particle -Fluid InteractionLiquid Particle -Fluid Interaction
Stokes’ law l
D is p e r s e d P a r t i c le
d
C o n t in u o u s P h a s ec , c
e z
e
e r
F D F B
tCD VF 3
forceDrag
gF cdb
6
forceBouyant 3
Particle MotionParticle Motion
aVC
t
18
2
r
ua
a
2
onaccelarati lCentrifuga
, where
Terminal velocity Separation is a function of:
– Density difference– Particle size– Continuous phase viscosity– Cyclone diameter
Local accelerations in 10mm cyclone may approach 10,000 g
Measuring the PerformanceMeasuring the Performance
Many ways to measure hydrocyclone performance
– Due to different applications
“Traditional” separation measurement:
QQFFCCF F ffFF((ll))
QQUUCCU U ffUU((ll))
QQOOCCOO ffOO((ll))
f
f
f R
R
RE
1
E
1
WW
OO
F
O
F
O
F
O
O
O
feedinenteringoilofmass
placerightexitingoilofmassE
Separation EfficiencySeparation Efficiency
• Efficiency based on total fraction of concentration reduction or:
• Equivalent to “traditional” efficiency measurement
F
UFu C
CC
Separation TheorySeparation Theory
Grade underflow purity coefficient-separation efficiency for each particle size
Integrating over sizes yields overall separation efficiency
FF
uuFFu fC
fCfCG
F
uFFuu C
CCdfG
0
Grade Efficiency CurveGrade Efficiency Curve
Continuous function of particles sizes
Hydrocyclone performance is size dependent and GEC varies with particles size
Graphically represented as curve that is usually ‘S’ shaped
“Overall” separation efficiency is a result of the integration of the product of the GPC and the feed distribution
Grade Efficiency CurveGrade Efficiency Curve
Wesson & Petty 1994
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 10 100
DROP DIAMETER, m icrons
UN
DE
RF
LO
W G
RA
DE
PU
RIT
Y C
OE
FF
ICIE
NT
5 0l
4
)2ln(exp1)(
50
50
l
l
llG
b
U
Separation ExperimentsSeparation Experiments
Flow DiagramFlow Diagram
Pump
P
F O
V1
V2
V3 V4
V5
FF
OF
UF
V6 V7
Stirrer
Drain
F neHydrocyclo
Tank
P
P
U
10mm Hydrocyclone10mm Hydrocyclone
2.5 mm2.5 mm
2.5 mm2.5 mm
1 mm1 mm
80 mm80 mm
10 mm10 mm
Experimental Flow LoopExperimental Flow Loop
tank
SampleCylinders
pump
hydrocyclone
Stirrer
Flow PredictionsFlow Predictions
Feed pressure varied from 60 - 160 psigFlow rates determined using stopwatchLinear regression
Qf = f(Po, Pu)
f)()()()()(Q 2/12/1f OUOUUO PePdPPcPbPa
Flow PredictionsFlow Predictions
Feed vs Prediction
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0
Feed Flow Rate, lpm
Pre
dict
ion
Flow Rate PredictionsFlow Rate Predictions
0 20 40 60 80 100 120 140 1600
40
80
120
160
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Qf, L/min
Dpo, psig
Dpu, psig
4.5-5.0
4.0-4.5
3.5-4.0
3.0-3.5
2.5-3.0
2.0-2.5
1.5-2.0
1.0-1.5
0.5-1.0
0.0-0.5
ExperimentExperiment• Determine optimum conditions which will give
the best separation efficiency
• Compare concentration separation efficiency with traditional way of determining efficiency.
Run Feed Press Drop, psig Flow rate,L/min
1 60 3.0
2 80 3.4
3 100 3.7
4 120 4.1
5 140 4.5
6 160 4.8
Solid-Liquid Separation Solid-Liquid Separation ExperimentsExperiments
Model DispersionModel Dispersion
Soda Lime Borosilicate Glass glass bubbles and water :
= 0.1 g/cm3
c = 1 cp (Cannon-Fenske viscometer)
lmean = 30 m
ResultsResults Conc vs. oil droplet sizes at 60 psi pressure drop
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.1 1 10 100 1000
Diameter, m
Vol
con
c., p
pm
feed
underflow
ResultsResults Conc vs. oil droplet sizes at 60 psi pressure drop
00.10.20.30.40.50.60.70.80.9
1
0.1 1 10 100 1000
Diameter, m
Gra
de
Pu
tiry
Coe
ffic
ien
t
4.85 lpm
2.8 lpm
ResultsResults Grade Purity Function vs. Diameter – 4.85 lpm
00.10.20.30.40.50.60.70.80.9
1
0.1 1 10 100 1000
Diameter, m
Gra
de
Pu
tiry
Coe
ffic
ien
t
4.85 lpm
)2ln(exp1)(
50
b
U l
llG
l50=10m
b=3
ResultsResults Overall efficiency vs. Feed flow rate
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
4.0 4.2 4.4 4.6 4.8 5.0
Feed Flow Rate (lpm)
Ove
rall
Eff
icie
ncy
ConclusionsConclusions
Glass bubbles-water separation– Best overall efficiency for feed
distribution occurs 4.8 lpm feed flow rate (P=200 psi)
– L50 = 10 m
Liquid-Liquid Separation Liquid-Liquid Separation ExperimentsExperiments
Model DispersionModel Dispersion
Vegetable oil dispersion in water:
= 0.1 g/cm3 (pycnometer)
d = 50 cp (Cannon-Fenske viscometer)
c = 1 cp (Cannon-Fenske viscometer)
30 dynes/cm (Pendant drop method)
ResultsResults Conc vs. oil droplet sizes at 60 psi P
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.1 1 10 100 1000
sizes, microns
Vol c
onc,
ppm
Feed
Underflow
ResultsResultsConc. vs oil droplet sizes at 160 P
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.1 1 10 100 1000
sizes, m icrons
Vo
l co
nc,
pp
m
Feed
Underflow
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
0.1 1 10 100 1000
diameter, m
Gra
de
Pu
rity
Co
eff 3
3.4
3.7
4.1
4.5
4.8
Concentration G-curvesConcentration G-curves Grade Purity Coefficient vs. Oil droplet diameter at various flow rates
L/minL/min
lfC
lfClfClG
FF
UUFF
best GPC-curve
“Drop Breakup”
ResultsResults
The best “overall” efficiency?
Run Feed-pressure drop,psig
Flowrate, l/min Efficiency, u
1 60 3.0 63
2 80 3.4 53
3 100 3.7 56
4 120 4.1 56
5 140 4.5 55
6 160 4.8 32
ConclusionsConclusions
Oil-Water separation– Best overall efficiency for feed
distribution occurs 3.0 lpm feed flow rate (P=60 psi)
– Best GPC curve occurs at 3.7 lpm feed flow rate (P=100 psi)
Continued WorkContinued Work
• Investigate drop breakup
• Investigate source of ‘fish hook”
• Investigate use of back pressure to eliminate the air from the core vortex