1Northern California Pipe Users Group

Advanced Tools for Evaluation of Pump IntakesJoe Orlins, PE, PhD, PMP, D.WREAVP, Hydraulic Engineering & SystemsJoe.Orlins@aecom.com

June 9, 2020 | 10:00 am – 2:00 pm

Northern California Pipe Users Group

Interview | January 16, 2020

2Northern California Pipe Users Group

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

joe.orlins@aecom.com