Advanced Tools for Evaluation of Pump Intakes...Evaluation of Pump Intakes Joe Orlins, PE, PhD, PMP,...

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