12 Ernie Sturtz Pumping Facility Design Standards

8/9/2019 12 Ernie Sturtz Pumping Facility Design Standards

1/41

DESIGN STANDARDS

FOR PUMPING FACILITIES“READING THE TEXT BOOKS”

February 12, 2013

Ernest C Sturtz, P.E., BCEE


2/41

Ernest Sturtz, P.E., BCEEPump Station Design

• More than 35 years hydraulic systems and

pump station design and construction experience

• CDM’s Senior technical leader for pump

station design

• Member of several Hydraulic Institute Standards

Committees Including Intake, Vibration, NPSH/AOR

and Pump Piping. Co-Chair of Pump Application

Guidelines for Water and Wastewater

• Technical oversight for hundreds of pump stations

around the globe during career, many in Texas


3/41

Today’s Topics

The “Textbooks” – “Pumping Station Design” Jones, Sanks, et al

– “Pump Handbook” Karassik, Krutzsch, Fraser & Messina

– Hydraulic Institute Design Standards

• Intake Design Standard ANSI/HI 9.8-2012 – Inlet/Wet Well Configuration Design

• Pump Piping Standard ANSI/HI 9.6.6-2009

• Vibration Standards ANSI/HI 9.6.4-2009 & “Dynamics”

• NPSH/AOR Standards ANSI/HI 9.6.3 & 9.6.1

– Hydraulic Institute “Textbooks”

• “Pump Life Cycle Costs”

• “Variable Speed Pumping”

• “Optimizing Pumping Systems”


4/41

What is the Hydraulic Institute and what is a

“Standards Partner”?

• US organization founded in 1917 to create pump

related standards and solve pump related issues

• Members are Pump Manufacturers

• The Hydraulic Institute prepares design standards for

all aspects of pumping (issued under ANSI)

• Associate Members are manufacturers of related

equipment such as motors, VFDs and controls

• Standards Partners are consultants and end users

that contribute to preparation of design standards


5/41

Pump Intake Design Standard

• HI has released an updated

Pump Intake Design Standard

(ANSI/HI 9.8-2012)

• Design Requirements – Avoid:

– Submerged vortices

– Free-surface vortices

– Excessive swirl

– Non-uniform velocity

distribution at impeller eye

– Excessive variations in velocityand swirl

– Entrained air

Image used with permission of Hydraulic Institute


6/41

Wet Well Design

• Perhaps one of the most common sources of pump

and wastewater pumping station maintenance

problems

• Challenges – the Designer must select a type that:

– Minimizes dynamic energy and large scale water

circulation

– Avoids solids deposition

– Provides a mechanism to create turbulence in wet well

to re-entrain solids and to pump floating grease and

debris (Wastewater Pumping Stations)


7/41

Inlet/Wetwell Configuration Design

• Applicable Hydraulic Institute Standard

– Pump Intake Design ANSI/HI 9.8-2012

• Debris Management/Removal (WW & RW)

• Wetwell Configuration Selection

• Wetwell Inlet/Pump Approach

• Redundancy/Split Wetwells


8/41

Self-Cleaning

Trench Style

Wet Well

• Design Guidance

available from

ANSI/HI 9.8-2012 &“Pumping Station

Design” 3rd Edition

plus web resources


9/41


10/41

Compact Rectangular Wet Well

for Solids Bearing Liquids

• In HI Intake Standard

Appendix

• Design has undergone

extensive hydraulic

modeling by HydroTec(Leeds, England) and Flygt

• Proven by extensive field

testing

• Works effectively for both

variable and constantspeed applications

Image used with permission of Hydraulic Institute and Xylem Corp.


11/41

Example: Sugar Creek Influent Pump Station

– Physical Hydraulic Modeling

• Physical Modeling Verifies Hydraulic Design

• Modeling Required for Stations Exceeding100,000 gpm (144 mgd)

• Allows Optimization of the Design


12/41

Pump Piping Design Standard

• HI released a new Pump Piping

Standard (ANSI/HI 9.6.6-2009)

• Valves and fittings can generatehydraulic conditions that can

adversely affect pump

performance

• Standard identifiesrecommended length of straight

pipe upstream of pump inlet



13/41

Pump Suction Piping



14/41

Pump Suction Piping

Images used with permission of Hydraulic Institute


15/41

Vertically Mounted End-Suction Pumps

• Non-reducing elbow design

has been common practice

• Results in uneven flow

distribution to the pump

inlet• Introduces uneven loading

on impeller

• Reducing elbow has been

shown to be effective at

delivering uniformhydraulics to the pump

inlet


16/41

Recommended Pump Suction Elbow Design

for Delivery of Uniform Flow to the Pump


17/41

Design Guidance Recommendations


18/41

Pump NPSH and AOR Standards

• HI has released the updated Allowable

Operating Region (AOR) standard in

2012 and Pump NPSH (Net Positive

Suction Head) will be released in 2013

• These two standards cover how toselect pumps to prevent cavitation and

apply pumps to particular operating

ranges

• For instance – why do we add margin to

NPSH3 and what is NPSH3? What isNPSH?

• AOR & POR will be discussed in the

following slides



19/41

Pump NPSH Margin



20/41

Pump Selection and Operating Ranges

• Low static head systems generally facilitate a wider range

of operating conditions

• Reduced speed pumping can cause pump clogging

– Suction recirculation – Low suction velocities

• Focus on maximizing efficiency in the most common

operating conditions, while maintaining capacity

requirements for unusual operating conditions


21/41

Pump Selection Example for Low Static Head System


22/41

Pump Selection Example for High Static Head System


23/41

Common Pump Selection Mistakes – Pump Run-out


24/41


25/41

Pump Vibration Standard

• HI released updated Pump

Vibration Standard (ANSI/HI

9.6.4-2009)

• Depicts maximum allowable

vibration levels for different

pump designs

• Specifies how field and factory

vibration tests are to be

determined

•Will have a companion tutorial

entitled “Vibration Dynamics” to

be released in 2013



26/41




27/41




28/41

Pump/Mechanical/Piping Design

How do we put this all together?

• Pump Types

• Applicable Hydraulic Institute Standards

– Pump Piping

– Vibration

• Suction Piping

• Discharge Piping/Pump Supports/Shafting

• Pump Selection


29/41

Suction Piping & Inlet Design – Intake Design

Combine Intake & Pump Piping

Image used with permission of Hydraulic Institute and Xylem Corp.


30/41

Discharge Piping/

Pump Supports/Shafting

Hydraulics

– Pump suction elbows

and reducers can be

problematic

– Air entrainment,pre-swirl, non-uniform

flow distribution, vortices

– Poor piping design can

contribute to ragging &vibration

– Proper pump selection

– NPSH - cavitation


31/41

Discharge Piping/


Flexible Couplings

& Pipe Supports

– Reduce rigidity

of system

– Introduce lateralload opposite the

pump discharge

– HI requires that

loads on suctionand discharge

nozzle be

minimized

h /


32/41

Discharge Piping/


Pump Supports – Major contributor to pump vibration

– Steel frames provided bymany manufacturers lack

adequate stiffness – Addition of steel cross

members is effective forvibration control, but limitsaccess

– Construction of base iscritical to minimizingvibration - proper grouting,securing anchor bolts, etc.

/


33/41

Discharge Piping/


• Use of concrete pump

supports preferred

• Provide concrete pedestal

type pipe supports

•Avoid use of flexible

expansion joints unless

seismic considerations

require use

• Pipe restraint must be

designed to reduce thrust

loading and other forces on

pump nozzles below

manufacturers limits


34/41

Vertically Mounted WW Pump Base

• Use concrete pedestals

instead of steel frames

whenever practical

• Designer must provide

space for suction elbow

and maintenance

access

Di h Pi i /


35/41

Discharge Piping/


What is a “Critical Speed”• System natural frequency is equal to a resonance

generated by the pump i.e., pump speed, vane-pass

frequency, etc.

– Variable speed systemsare especially vulnerable

to this problem

– Often system is

modified to move

natural frequency

out of operating range

– Can also speed limit

or exclude speeds


36/41

Vibration and Critical Speed Limitations

• Finite Element Analysis

– What is a Finite Element Analysis (FEA)?

• Computer model of mechanical equipment to predict natural

frequencies and equipment or structure behavior when excited

– FEA should normally be performed for pumps greater than 100HPand of a critical nature

– FEA should only be performed by qualified firms

– Investment in FEA is a proactive approach similar in philosophy to

Physical Intake Model


37/41


38/41


39/41

Life Cycle Cost Analysis

• Secure Financial Information

on Facility

• Use Appropriate Software or

Spreadsheet to Analyze PumpFacility

• Use Hydraulic Institute Text as

Guide

Image used with permission of

Hydraulic Institute


40/41

Comparison of facilities

over 20 years

• Cost of Money

• Lowest First Cost

• Not the most Efficient

Pump/MotorCombination

• Fiberglass Wet Well

and Valve Vault

• Lowest Cost Valves

• Thin Wall PVC Pipe

• Cost of Money–Same?

• Higher Equipment Cost

• Most Efficient

Pump/Motor/VFDEquipment Available?

• Concrete Wet Well & Vault

with Coatings

• First Quality Accessories

• Ductile Iron Pipe


41/41

Questions?

12 Ernie Sturtz Pumping Facility Design Standards

Documents

Transcript of 12 Ernie Sturtz Pumping Facility Design Standards