Download PDF - Calgary Pump Symposium

The Design and Testing 

of a 

New Centrifugal Pump Design 

for 

Bitumen Froth Applications 

Presentation for the Calgary Pump Symposium, Nov. 13, 2009 

R. Visintainer / Nov-2009 

© 2009 GIW Industries Inc.

Froth and Viscous 

Losses 

s 

2 © 2009 GIW Industries 

R. Visintainer

Bitumen Froth Losses – Head (Pressure) 

Summary of the primary 

losses in viscous froth and 

the factors affecting them. 

Clear water: pump 

design & speed. 

Viscosity effect: 

bitumen properties, 

temperature. 

Density effect: % air. 

Airlock: % air, viscosity, 

froth properties, flowrate, 

system & pump design. 


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Bitumen Froth Losses – NPSHR 








temperature. 






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Strategies for Improving Froth Pump Performance 

Improve suction inlet conditions: 

 

Increase NPSHA 

 

Decrease % air 

 

Increase pump inlet diameter 

Increase pump head without increasing speed: 

 

Increase impeller diameter 

 

High head impeller design 

Control airlock: 

 

Adjust froth properties 

 

Prevent (or delay) airlock formation 

 

Airlock venting 

Focus of this research project. 


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Test Setup 


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Froth Test Rig – GIW Hydraulic Lab 


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Froth Test Rig – Sparger Design 


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Froth Test Rig – Clear Suction Spool 


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Froth Test Rig – Testing Parameters 

• Viscosity: 

o 

o 

1 cSt (water) 

500 to 10,000 cSt (corn syrup) 

• Air: 0% to 30% 

• Flow: 1000 

– 3000 m 3 /hr 

• Head: 10 to 60 m 

• Speed: 300 to 800 rpm 

• Suction pressure: 0.0 to 1.0 atm 


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Airlock 


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Airlock – Low Re Number (laminar) 

Airlock forms as elongated 

bubble in suction piping. 


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Airlock – High Re Number (turbulent) 

Notice density difference 

between froth in impeller 

passages and casing. 

Also formation of airlock 

bubble in suction. 


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Airlock – Some Typical Results 

airlock 


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“Excess Air” Concept – Suction Inlet Coalescence 

Onset of airlock coincides with 

appearance of coalesced air in 

suction piping. 


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Strategies for Controlling Airlock 

Adjust froth properties: 

 

Decrease % air in the process 

 

Increase suction inlet velocity (works against improved 

NPSHR) 

 

Prevent “excess” air from reaching the suction inlet 

(improved design of sumps and launders) 

Prevent (or delay) airlock formation: 

 

Airlock disturbance (open shrouded designs) 

 

Improved NPSHR performance 

 

High head impeller design 

Focus of this research project. 

Airlock venting: 

 

Suction inlet venting (removes coalesced air) 

 

Internal pump venting 


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Airlock Venting System 


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excess air 

P SUCTION > P VENT 

froth 

Suction pressure must exceed vent pressure 

(usually atmospheric) by at least 10 kPa 

excess air 

froth 


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Vent pipe: Use hard pipe with heat 

strips in bitumen applications. 


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Airlock Venting System – Some Typical Results 

vent closed, 

typical airlock losses 

vent opened, 

airlock losses controlled 


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Airlock Venting System – Some Typical Results 


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Airlock Venting System – Viscous Froth 

OPERATION OF AIR VENT - AIR LOCK REMOVAL 

500-700 rpm, 3000 m3/hr, corn syrup at approx 3,000 cSt, 15% air plus 5% excess air added at sparger 

Airlock venting 


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High Head 

Impeller Design 


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High Head vs. Conventional Designs 








temperature. 

Conventional design 

(without venting) 






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Advantage of High Head 

design operating at same 

speed and NPSHR. 

High Head design 

(with venting) 

High Head design 

(without venting) 





temperature. 






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High Head Impeller Design – CFD Analysis 

CFD analysis used to 

optimize NPSHR 

performance. 

HIGH SUCTION SIDE VELOCITY 

@ SHOCKLESS DESIGN FLOWRATE ENTRY 

NEGATIVE NPSHR IMPACT 


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Turbulence 

helps to disturb 

airlock formation 

Conventional Closed Shroud Design 

Expanded, Open Shrouded Design 


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Higher head = more 

gas compression 

Conventional Closed Shroud Design 

Expanded, Open Shrouded Design 


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Some sacrifice in Efficiency 

Increased Head 

Improved NPSHR 

at higher flows 


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High Head Impeller NPSHR Performance 

Variable speed NPSHR testing 

ti 

Water froth - 0.03% soap 

100% BEPQ 

600 - 810 rpm 


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Viscous 

Effects 


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Viscous Froth Simulation 

Corn syrup at 3,000 cSt 


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Viscous Froth Simulation 

Corn syrup froth at 15% air 

and 3,000 cSt 


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Viscous Testing and Analysis – Typical Results 

Viscosity 

Correlations 

HEAD 

1,000 to 10,000000 cSt 

10-15% air 

0% excess air 

0.05 to 0.1 atm Ps 

scaled to 700 rpm 


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Viscosity 

Correlations 

FLOW 

1,000 to 10,000000 cSt 

10-15% air 

0% excess air 

0.05 to 0.1 atm Ps 



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Viscosity 

Correlations 

EFFICIENCY 

1,000 to 10,000000 cSt 

10-15% air 

0% excess air 

0.05 to 0.1 atm Ps 



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Viscosity 

Correlations 

POWER 

1,000 to 10,000000 cSt 

10-15% air 

0% excess air 

0.05 to 0.1 atm Ps 



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Key 

Learnings 


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Key Learnings 

• Given enough air, the pump will airlock. 

• The “Excess Air” concept: 

‣ Airlock occurs when the liquid is carrying more air than it can hold. 

‣ For conventional designs in clear water: 3% to 5%. 

‣ Depending on composition of froth, can increase to 40% or more. 

• Airlock can be delayed by… 

‣ … airlock venting systems (requires suction pressure > atmospheric). 

‣ … high head impeller designs adjusted for good NPSHR performance. 

• High head impeller design can improve froth pump performance by… 

‣ … reducing operating speed thus improving NPSHR performance. 

‣ … more airlock disturbance. 

‣ … better air compression within the impeller. 


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Questions 

& 

Discussion 


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