Truck Unloading Air Eliminators - Pro-Kut Air Eliminator · · 2009-10-01Truck Unloading Air...

PURPOSE The purpose of an air eliminator is to remove the gas

or air bubbles entrained in the fluid being pumped off

the truck.

Removing the bubbles, or void fraction, improves the

accuracy and performance of the meter.

When the fluid density is used to calculate the water

cut (Net Oil Calculation), removing the void fraction

increases the fluid density, which will increase the

calculated water cut.

Truck Unloading Air Eliminators

Void Fraction

The percentage or volume of product in a

meter that is composed of gas or air

bubbles.

8.2% Void Fraction


Void Fraction

The effect on void fraction in a PD or turbine meter isobvious, an 8.2% void fraction would cause the meterto read 8.2% higher than the actual fluid volume. Thegas or air simply takes up the space in the meter.

8.2% Void Fraction


Sources of Void Fraction

• Fluid being measured at or near bubble point.

• Introduction of air into the fluid, i.e. the truck pump.

• At the start of a load, hoses empty.• Switching tanks or compartments.• The end of a load.


Void Fraction

The effect of void fraction in a Coriolis Meter.

• Causes the drive coil input to increase – shock

absorber effect.

• Reduces the measured density of the fluid.

• Some newer coriolis meters can accurately measure

the mass of the fluid at significant void fraction

levels.


Ways to Reduce Void Fraction

• Increase back pressure on system to prevent

flashing.

• Increase back pressure to reduce the bubble

size.

• Increase pumping pressure to reduce the

amount of air the truck pump can move through

the meter.

• Install an air eliminator to remove the gas and

air from the fluid.


Effect of Void Fraction on Density Measurement

• Reduces the measured Density

Example: Water Density = 1150 kg/m3

5% Void Fraction in Fluid

Indicated Density = (1150 x 0.95) + (1.2 x 0.05)

= 1092.5 + 0.06

= 1092.6 kg/m3


Net Oil Calculation (NOC)

• Calculates Water percentage based on fluid densities

Water % = (Fluid Density – Oil Density) x 100

(Water Density – Oil Density)

Ex: Oil – 830 kg/m3 Water-1150 kg/m3 Fluid 935 kg/m3

Water % = (935 – 830) x 100

(1150 – 830)

= 32.8%



• Effect of 5% Void Fraction

Ex: Oil – 830 kg/m3 Water-1150 kg/m3 Fluid 1092.6

kg/m3

Water % = (1092.6 – 830) x 100 = 82.1%

(1150 – 830)

What you pay for = 17.9% Oil !

Reality = 100% Water !



• Effect of 25% Void Fraction

Ex: Oil – 830 kg/m3 Water-1150 kg/m3 Fluid 862.8 kg/m3

Water % = (862.8 – 830) x 100 = 10.25%

(1150 – 830)

What you pay for = 89.75% Oil !

Reality = 100% Water !


Case #1 - A Tale of Two Meters

• Identical parallel meter runs

• M. M. D Body c/w 9739 transmitters

•One meter run with a Pro-Kut Air Eliminator and back pressure valve, and the other parallel meter run with no air eliminator or back pressure valve.


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Flo

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m3

/min

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m/c

c

Time in Seconds

East Riser Load 1 - 100% Water for Full Load

Density gm/cc Flow Rate m3/min

No data from meter at end of

load. 100% water at sample

point for entire load. Slug flow

for 58 seconds, water air mix,

but no fluid measurement.

58 Second

interval

Without Air Eliminator


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m/c

c

Time seconds

East Riser Load 2 - Emulsion Full Load

Density Flow Rate

Tank SwitchRecorded flowvery erratic or at zero



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c

Time Seconds

East Riser Load 2 – Emulsion at Tank Switch

Density gm/cc

Flow Rate m3/min

1 Minute 40 second tank Switch

Gaps in data during sensor failand slug flow



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/min

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m/c

c

Time Seconds

West Riset Load 1 - End of Condensate Load

Density gm/cc

Flow Rate m3/min

No change in density - no air in fluid during unload

With Air Eliminator


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Time - Seconds

West Riser - Emulsion Load 2

Density gm/cc

Flow Rate m3/min

Tank Switch

With Air Eliminator

Increasing oil percentage


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West Riser - Load 3 Emulsion

Density gm/cc

Flow Rate m3/min

Tank Switches

Density very Stable Density dropped for only 6 secondsat end of tank switch

With Air Eliminator


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m3

/min

ute

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m/c

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Time Seconds

West Riser - Full Emulsion Load 3 At Tank Switch

Density gm/cc

Flow Rate m3/min

6 second low density interval

2 minute tank switch interval

With A.E.


Case #2 – Same Meter Run

• First slide – inline horizontal air eliminator

•Second slide – same meter run with Pro-Kut Air Eliminator

• M. M. 3” Elite with 2700 Transmitter


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M3

/hr

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g/m

3

Time Seconds

Riser #2 Flow Pattern with 3" In Line Horizontal Air Eliminator

Density

Flow rate

Flow pattern from the meter in 2 second

intervals during the switch from the back to

the lead trailer. Gaps in lines indicates slug

flow and sensor failure due to entrained gas

from truck pump. Air eliminator was cycling

and dumping..

With Low Capacity in line Air Eliminator


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g/m

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Tme Seconds

Riser #2 Flow pattern with 3" Pro-Kut Air Eliminator

Density kg/m3

Flow Rate m3/hr

Flow pattern with vertical air eliminator

during tank switch on back and lead tanks

and end of load.

With Pro-Kut Air Eliminator


Case #3 – Same Meter Run

• First slide – No air eliminator

•Second and third slide – same meter run with Pro-Kut Air Eliminator

•Same truck and driver for both situations

•First load is meter run with no air eliminator – 100% water

•Second load is same meter run with Pro-Kut Air Eliminator with small amount of oil at the top of each tank

• M. M. 3” D body with 9739 Transmitter


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g/m

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Time Seconds

Battery 1 Truck Unload Meter Flow Pattern - No Air Eliminator

Density kg/m3

Flow Rate m3/hrTank Switch


-10

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g/m

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Time Seconds

Battery 1 Emulsion Load with Pro-Kut Air Eliminator - Oil At end of Truck Tank Volumes

Density kg/m3

Flow Rate m3/hr

Tank Switch


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Time Seconds

Battery 1 Emulsion Load at Tank Switch

Density kg/m3

Flow Rate m3/hr

Tank Switch

Density dropping as oilat the top of the truck tankstarts to enter meter

With Air Eliminator

Truck Unloading Air Eliminators - Pro-Kut Air Eliminator · · 2009-10-01Truck Unloading Air...

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