TUSTP 2003
DOE Project:
HORIZONTAL PIPE SEPARATOR
(HPS©)
By
Ciro A. Pérez
May, 2003
Topics
 Objectives
 Physical phenomena in HPS
 Modeling approach
 Experimental program
 Conclusions - Future work
Objectives
 Study the behavior of oil-water mixtures in
horizontal pipes
 Develop a mechanistic model that predicts
separation efficiency for given fluids, geometry
and flow rates
 Compare/refine model with data obtained in this
study and from literature
 Study effects of using manifolds to install
multiple separators in parallel
Topics
 Objectives
 Physical phenomena in HPS
 Modeling approach
 Experimental program
 Conclusions - Future Work
Physical phenomena in HPS
Direction of flow
Inlet
Outlets
Zone 3
Zone 1
Zone 2
Zone 4
Oil
Oil with Water droplets
Packed water droplets in oil
Packed oil droplets in water
Water with Oil droplets
Water
Physical phenomena in HPS
 Oil-Water mixture enters HPS, with droplet distribution
function of processes upstream. Some mixing can occur at
inlet (Zone 1)
 Inside HPS the velocity decreases, turbulence decreases
(laminar flow might be reached), settling and coalescence
are promoted (Zone 2), layers begin to develop
 Up to 6 layers can develop (Zone 3):
- Pure Oil
- Oil with water droplets
- Packed water droplets in oil
- Packed oil droplets in water
- Water with oil droplets
- Pure water
 Eventually steady state is reached (Zone 4)
Physical phenomena in HPS
 Regimes of operation in HPS
 Laminar flow is desirable as it promotes segregation
 Oil is more likely to flow to be in laminar flow conditions
due to higher viscosity
 So, desirable flow regimes are:
- Laminar Oil Flow - Laminar Water Flow
- Laminar Oil Flow - Turbulent Water Flow
 Study flow in HPS requires:
- Steady state conditions:
max segregation
- Transient conditions:
how long it will take
Topics
 Objectives
 Physical phenomena in HPS
 Modeling approach
 Experimental program
 Conclusions - Future work
Modeling approach
Previous studies
Proposed model
Modeling approach
Previous studies
a. 1D Mechanistic approach: Barnea-Brauner (1991)
b. 2D Analytical approach (for laminar flows): Brauner
(1998)
c. Numerical approach
- Shoham-Taitel (1984, gas-liquid)
- Elseth et al. (2000, VOF method)
- Gao et al. (2003, VOF method)
1D mechanistic approach leads to simple solutions, so it
will be used as an initial approach
Modeling approach
Proposed model:
1- 1D stratified flow pattern model is applied for given fluids
and flow rates. If flow is stable, flow characteristics are
given by the model
2- If flow is unstable, following procedure applies:
- An amount of more viscous phase is assumed to flow to
the less viscous phase
- For this new flow rate, properties are calculated for
mixture, segregated flow is assumed, and stability is
checked. Migration stops when stability is reached
- No convergence means non segregated flow
Modeling approach
Preliminary results
Model tested against experimental data (Shi et. Al (2000))
 Test conditions:
- Oil properties: 3 cp, 800 kg/m3
- Water properties: 1 cp, 1100 kg/m3
- Pipe: 0.1 m ID, 18m long
- Mixture velocity: 0.4 to 3 m/s
- Water Cut: 0.2, 0.4, 0.6, 0.8
 Trallero (1995) model used, Sheltering Factor assumed 0
 Increased interfacial friction factor as mixing and waves form
at the interface
Modeling approach
Results: Pure oil and water layer thickness
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Experimental OilMix level
Experimental MixWater Layer
Model Oil-Mix layer
60% WC
Model Mix-Water
Layer
0
0.5
1
1.5
Mixture Velocity m/s
hl/D
hl/D
40% WC
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Experimental OilMix level
Experimental MixWater layer
Model Oil-Mix
Layer
Model Mix-Water
Layer
0
0.5
1
Mixture velocity m/s
1.5
Topics
 Objectives
 Physical phenomena in HPS
 Modeling approach
 Experimental program
 Conclusions - Future work
Experimental program
Test Section
Experimental program
 Calibration:
Level: Pipe centerline was leveled in +-3/32”
range from the horizontal
Level sensors: For operating conditions, level
meters are able to detect continuous interface
with error of 3/32”
Experimental program
 Typical level meter signal at interface
Sensor 2 signal function of dimensionless height
hl/D
Sensor
stem gap:
7/32”
1
0.9
0.8
0.7
0.6
Test 1
Test 2
Test 3
Test 4
Top of sensor
Bottom of sensor
0.5
0.4
0.3
0.2
0.1
0
0
1
2
3
Voltage
4
5
Experimental program
 Pitot / Isokinetic sampling probe
Previous works:
- Khor, Mendes-Tatsis and Hewitt (1996)
- Vedapuri, Bessette and Jepson (1997)
- Shi, Cai and Jepson (1999)
- Cai, Gopal and Jepson (2000)
Experimental program
 Pitot / Isokinetic sampling probe
Characteristics
- ID= 3/16”
- OD= 11/32”
- Operating dP: 0 to 1” H2O, accuracy dP 0.15%
- Range of operation:
. Min. velocity: 0.06 m/s (error 10% )
. Max. velocity : 0.7 m/s (error 0.073% )
Experimental program
 Photo of assembled probe:
Sampling outlet
Pressure outlets
Base
Pitot
Experimental program
 Pitot / Isokinetic sampling probe in place
Experimental program
 Pitot / Isokinetic sampling probe
- Calibration results for single phase
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Distance from
wall
200 lbs/min water
1.71875
0.3
1.46875
1.21875
0.96875
0.71875
0.46875
0.21875
0
0.5
1
1.5
Distance from centerline (inches)
0.03125
Theoretical
Distance from
wall
1.75
1.5
0.25
Velocity (m/s)
Velocity (m/s)
150 lbs/min oil
1.25
0.2
1
0.15
0.75
0.1
0.5
0.05
0.25
0
0
0.5
1
1.5
Distance from centerline (inches)
0
Theoretical
Experimental program
 Pitot / Isokinetic sampling probe
-
Problems when measuring oil-water flow. After flushing
with oil, water floods pitot, capillarity causes oscillations in
dP while flooding
Improved with wider pressure taps. dP values to be taken at
initial plateau, before flooding occurs.
Signal from dP, at 0.75" from bottom
6
5
4
Voltage
-
Test 3
Test 2
Test 1
3
2
1
Plateau
Flooding
0
0
20
40
Time (1/2 sec)
60
80
Experimental program
 Calibration results: Effects of oil-water flow
 Pitot filled with oil, mixture flowing Vsl=0.6 m/s, WC 60%
hl/D
Velocity Profile: Vmix=0.6 m/s, WC 60%
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Velocity Profile
0
0.2
0.4
0.6
Velocity (m/s)
0.8
1
Topics
 Objectives
 Physical Phenomena in HPS
 Modeling approach
 Experimental program
 Conclusions/ Future Work
Conclusions/Future Work
 Initial model for all flow conditions is proposed.
Actual model underpredicts thickness of pure
fluid zones
 Model requires higher interfacial shear stress
when mixing layers are present
 Pitot measurements for low velocities are
affected by capillarity in pitot pressure taps
Measurement criterion was adapted for this
condition
Future work
 Measurement of velocity profiles for experimental
matrix
 Measurement of hold up for experimental matrix
 Hold up/Interfacial friction factor adjustment with
experimental data and literature data
HORIZONTAL PIPE SEPARATOR
(HPS©)
Questions?