1Northern California Pipe Users Group
Advanced Tools for Evaluation of Pump IntakesJoe Orlins, PE, PhD, PMP, D.WREAVP, Hydraulic Engineering & [email protected]
June 9, 2020 | 10:00 am – 2:00 pm
Northern California Pipe Users Group
Interview | January 16, 2020
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Today’s Discussion
•Potential pump station
problems
•How to assess
problems?
•Case study
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Potential Pump Problems
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Potential Pump Problems
• Excessive levels of
- Noise
- Vibration
• Reduced performance
- Head, flow, efficiency
• Unsteady operation
• Prime loss or air binding
• Accelerated bearing wear
• Cavitation damage
• Component failure
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What Causes Pump Problems ?
• Mechanical issues
- Unbalanced rotor
- Misalignment
- Natural frequency resonance
• Hydraulic issues
- Non-uniform approach flow to pump
- Excessive turbulence
- Swirl approaching impeller
- Air entrainment
- Vortex formations
- Inadequate NPSH
- Internal recirculation
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Approach Flow Hydraulics: Common Problems
• Swirl Approaching Impeller
- Changes pressure distribution on blade
- Affects pump performance
- Can lead to cavitation, wear
• Non-Uniform Velocity Distribution
- Accelerated bearing wear
- Component fatigue failure
- Reduced performance
• Excessive Turbulence
- Accelerated bearing wear
- Component failure fatigue
- Reduced performance
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How to Assess These?
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Approach to Investigations
• Site inspections
• Document review
• Field measurements
- Shaft alignment
- Vibration, cavitation
- Operating conditions (head, flow, power)
- Visual techniques
• Modeling & analysis
- Physical hydraulic modeling
- Numerical hydraulic modeling
- Rotordynamic analysis
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Field Measurements
• Vibration & cavitation
- Natural frequencies
- Vibration “mapping” & analysis
- Video techniques
• Hydraulic performance
- Flow
- Discharge
- Efficiency
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Hydraulic Modeling Tools: CFD
• Computational Fluid Dynamics
- Assess approach flow to pump
- Evaluate internal flow patterns
• Can be used to evaluate expected
pump performance & mechanical
loads
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Hydraulic Modeling Tools: Physical Modeling
• Reduced-scale modeling
- Maintains dynamic similitude
• Balance of relevant forces
- Inertial vs. gravitational
- Inertial vs. viscous
• Able to quantify:
- Velocity distribution
- Turbulence
- Swirl
- Vortex formations
• Used to assess hydraulic problems &
develop remedial measures
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Case Study: Trickling Filter Pump Station
• Existing PS at WWTP
• Large pumps (61,500 gpm)
• Original pumps: vibration & shaft damage
• Where to put 5th pump?
6 ft
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Case Study: TFPS – Modeling Tools
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Summary
• Difficult to assess problems from the
outside
• Costly & disruptive to assess problems
from the inside
• Advanced modeling tools are:
- Non-invasive
- Effective for troubleshooting problems
- Allow development of cost effective
remedial measures
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Questions ?
Joe Orlins
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