type vs1 and vs6 vertical turbine pumpscalgarypumpsymposium.ca/uploads/2013pdfs/design... ·...

Calgary Pump Symposium 2013

Type VS1 and VS6 Vertical Turbine Pumps Wet Pit and Double Casing

Marc Buckler

Flowserve Corporation

Calgary Pump Symposium 2013 Calgary Pump Symposium 2013

Marc Buckler

Product Manager - Vertical Pumps Flowserve Corporation Taneytown, MD, USA


Topics

Configurations & Construction

Pump Features

Design & Analysis

Sump Design


Configurations &

Construction

Engineered Flexibility


Open – Product

Lubrication

Enclosed – Oil

Lubrication

OR

Open or Enclosed

Lineshaft Construction


Cast Discharge Head Fabricated Discharge Head

OR

Discharge Head Configurations


Above Ground

Suction

Below Ground

Suction

Below Ground

Discharge

Above Ground

Discharge

Suction & Discharge

Configurations


Semi-Open Impeller

Enclosed Impeller

Maintains efficiency by close running clearances between lower shroud and bowl

Provides an increase in efficiency over enclosed impellers

More suitable for services with solids

Limited in number of stages

Impeller Constructions


Enclosed Semi-Open

Impeller Constructions


Positively locked to shaft

Stainless steel slotted keys prevent radial movement

Stainless steel split ring keys prevent axial movement

Commonly used for extreme temperature applications

Keyed Impeller

Colleted Impeller

Provides interference fit between bowl shaft and impeller

Impeller Mounting

Configurations


Available on enclosed impellers

and most bowls

Installed with interference fit

Roll pins positively lock the rings

in place

Wear Ring Construction


Provides a positive seal of all

flanged joints

Located at rabbet fits on bowl

and column joints

Also included at discharge head

to suction can fit

O-Ring Construction


Various Mechanical Seals

Single, dual, split seals

Balanced or unbalanced

Piping plan 13 minimum

Stuffing Box (Packed Box)

Low, high, extra high packed

boxes

Plan 13 required for 100 psi

or greater

Sealing Configurations


Motors, Solid or Hollow Shaft Variable Frequency Drives

Engines with Right Angle Gear Drives

Steam Turbines

Driver Configurations


Question:

I have an application where the

pumping liquid is municipal water.

What pump configuration do I select?


Answer:

Consider a Wet-Pit VS1

with Product Lubrication


VS1 Standard Features

Product Lubrication


• Basket Strainer (Optional) Prevents unwanted debris from entering pump

Design exceeds HI standards

• Bell Bearing Provides maximum shaft support

Permanently grease lubricated for reliability

• Suction Bell Provides efficient flow into eye of first stage

impeller

• Sand Collar Prevents grit from entering into bell bearing

• Wear Rings (Optional) Renews clearances and efficiency

VTP Standard Features

Open-Product Lubrication


Lock Collet

Provides interference fit to hold impeller to bowl shaft

Impellers - Enclosed & Semi-Open

Designed for maximum coverage of all applications

Bowl Bearings

High length to diameter ratio on both sides of the

impeller to provide rigid support for the bowl shaft

Discharge Case or Bowl/Column Adapter

Hydraulic adapter ensures efficient transfer of flow to

various column sizes




• Open Lineshaft Construction Allows lineshaft bearings to be lubricated by pumped

liquid

• Bearing Bracket with Rubber Lineshaft Bearings Fits integrally between column sections to maintain

alignment

Spaced to provide adequate shaft support

• Column Pipe Available threaded as shown to minimize well casing

diameter




Discharge Head

ASME 125# or 250# flat face flange

Provides smooth transition of pumped liquid to

discharge piping

Functions as mounting base for driver

Pre-lubrication Connection

Allows external lubrication for deep set pumps

High Pressure Stuffing Box

Allows working pressures up to 20 bar (300 psi)

Vertical Hollow Shaft Motor

Extends head shaft through the motor

Provides impeller adjustment with an adjusting

nut at the top of the motor




Question:

What if my pumping liquid contains

some abrasives?


Answer:

Consider a Wet-Pit VS1

with Enclosed Lineshaft /

Oil Lubrication



Enclosed Lineshaft

Oil Lubrication


Tension Bearing Assembly with Oil

Tank

Holds the enclosing tube and lineshaft

bearings in alignment

Provides a chamber for the lubricant to

as it enters the enclosing tube

Oil tank provided with shut off valve,

sight feed regulator and lubrications lines


Enclosed-Oil Lubrication


Enclosing Tube Stabilizer

Maintains rigidity and alignment of the

enclosing tube

Enclosing Tube

Provides protection from the pumped liquid

Used with metal lineshaft bearings




Discharge Case with Bypass Port

Allows positive flow of the lubricant

into the enclosing tube to lubricate

lineshaft bearings




Fresh Water Injection Lubrication

Uses injection assembly with packing in lieu of tube tension assembly

Flush Line to Suction Bearing (up to 20 feet)

Provides fresh water flush to bowl bearings

Rifle Drilled Pump Shaft

Provides fresh water flush to bowl bearings

Optional Standard Features

Enclosed Lubrication


Question:

What if my application has limited

NPSH available?


Answer:

Consider a Double Casing VS6


Standard Features

Non-API VS6 Pump


Solid Shaft Motor with Thrust Bearing

Shaft extension allows motor to be coupled to pump

Includes thrust bearing to withstand the total

hydraulic thrust as well as the rotor weight

Motor Alignment

Precision rabbet fit aids in the alignment of the

motor to the pump shaft

Pumps with larger motors are supplied with motor

alignment screws

OSHA Non-Spark Coupling Guards

Provides safety while allowing visual inspection of

the coupling without guard removal

VPC Standard Features

Non-API Can Pump


Fabricated Discharge Head

Fabricated with ANSI 150# or 300# slip-on flanges

Functions as a mounting base for driver

0.50” NPT discharge pressure gauge, suction vent,

and drain taps

Lifting Lugs

Permits economical two point lifting method of

pump during installation and maintenance

Rigid, Adjustable Flanged Coupling

Provides the proper impeller clearance adjustment

A spacer coupling allows access to the mechanical

seal without removing the motor

High Pressure Seal Chamber

Accommodates low, high and extra high packed

boxes or mechanical seal arrangements


Non-API Can Pump


Fabricated Suction Can

Creates optimum hydraulic conditions through the

suction flange inlet into the suction bell

Threaded or Keyed Lineshaft Couplings

Positively locks sections of lineshaft together

Open Lineshaft Construction

Allows lineshaft bearings to be lubricated by the

pumped fluid

Flanged Column Assembly

Utilizes precision rabbet fits to ensure proper

alignment of each section

Provides transition from bowl assembly to discharge


Non-API Can Pump


Bearing Retainers with Bearings

Provides shaft support in column assembly

Retainers are spaced between column sections

Pumps with larger column sizes ( >16”) are supplied

with integral retainers

Enclosed or Semi-Open Impellers

Cast to provide smooth passageways for more

efficient fluid flow

First stage impeller available with low NPSH design

Colleted or Keyed Impellers

Provides method of fasting impeller to shaft with an

interference fit or a positive locking design


Non-API Can Pump


Question:

What if my application has limited

NPSH available and compliance to

API specifications are required?


Answer:

Consider a Double

Casing API VS6 Pump


Standard Features

API VS6 Pump


Motor Alignment Screws

Provided for use with motors over 500 pounds

Aids in the alignment of the motor to the pump

shaft

Solid Shaft Motor with Thrust Bearing

Motor shaft runout of 0.001 inch total indicated

runout (TIR) contributes to the low vibration and

overall pump and motor rotor balance

Precision, Rigid Adjustable Spacer

Coupling

Provides easy rotor lift adjustments for renewing

critical impeller clearances and pump efficiency

Allows seal removal without disturbing the motor


API Can Pump


Cartridge Mechanical Seal with Plan 13

Seal chamber is suitable for single or dual seals

Plan 13 provides continuous seal chamber venting

Seal Chamber with Jackscrews

Used to separate mating parts easily during disassembly

Weld Neck Flanges

Used for suction and discharge connections

Increase maximum allowable working pressure

Provide higher nozzle loading capabilities then threaded

or slip-on welded flanges

Flanged Vent Connection (Not Shown)

Allows pump to be vented upon initial operation

Can be pressurized to purge liquid from suction can

when a suction can drain is supplied


API Can Pump


Lineshaft Bearing Spacing

Optimized to ensure long bearing life, low

vibration and increased mechanical

seal life

Separate Sole Plate (Optional)

Allows removal of suction can without

disturbing the foundation

Internal Suction Can Drain (Optional)

Allows the suction can to be drained of

pumping liquid prior to removing the pump

Studs & Nuts

Prevent thread damage common with

capscrew removal


API Can Pump


One Piece Shaft

Eliminates threaded shaft couplings which cause

increased shaft runout, higher vibration and

weaker joints

Available up to 6 m (20 ft)

Open Lineshaft Construction

Keyed Impellers

Key and split-ring design positively locks the

impeller to the shaft, eliminating undesired

movement

O-Ring Construction

Provides a positive seal of all flanged joints

Located at rabbet fits on bowl and column joints

Also included at discharge head to suction can fit


API Can Pump


Pressure Casing

Consists of suction can and discharge head

Designed to ASME standards

Able to withstand API’s specified corrosion

allowances

Dynamically Balanced Impellers

Enclosed impellers balanced to ISO 1940-1

Gr G2.5

Bowl & Impeller Wear Rings

Provide a quick and easy way to renew

clearances and pump efficiency

Roll pins positively lock the rings in place

Impeller wear rings are integral as standard


API Can Pump


Pump Intake Design


Hydraulic Institute Standards Section 9.8

• Provides guidelines for

• Sump design

• Model studies

• Remedial measures


Sump Design

• Recommended design


Intake Model Study

• Model study recommended for:

• Single pump with flow > 40,000 gpm

• Total station flow > 100,000 gpm


Acceptance Criteria

• No organized free surface and/or subsurface

vortices should enter the pump

• Pre-swirl limited to 5° from the axial direction

• Velocity fluctuations at the impeller less

than 10%

• Time averaged velocities within +/- 10% of

the mean velocity (Turbulence)

Model Pump


Baseline Test

Sidewall Vortex

Floor Vortex

Surface Vortex


Remedial Measures

Modifications at entrance to pump bay Modifications in pump bay

Curtain Wall

Baffles

Grating

Fillet Splitter


Remedial Measures

Vane grating baskets


Final Testing

Flow along floor with modifications

Flow streamlines entering pump

Flow streamline along sidewall fillet


Suction Can Design

• Guidelines for:

• Can length

• Suction flange location

• Flow vanes

• Can diameter


Summary

• Potential problems identified and corrected using physical modeling

• The approach of using HI Standards with physical modeling provides the

best chance for success

• The approach minimizes performance problems, O&M costs, and outages


• Structural Analysis Includes:

Reed Critical Frequency (RCF) – Above Ground

– Below Ground

Nozzle Load Calculations

Foundation Load Calculations

Seismic Calculations

Anchor Bolt Calculations

Lifting Lug Calculations

• RotoDynamic Analysis Includes:

Torsional

Lateral

• Thermal Analysis

Elongation and stresses

Temperature gradient

Pump Analysis


Pump Analysis

Reed Critical Frequency Analysis

Why is it done?

Determine the natural frequency of the combined motor & pump system

Prevent excessive vibration


• When is it required?

All VFD applications

To meet Hydraulic Institute and API 610 vibration limits

Motors > 260 kW (350 HP)

Design speeds ≤ 900 rpm

Design speed ≥ 3000 rpm AND > 7.5 m (25 ft)

Customer request

• Inputs required

Motor Outline Drawing, Weight

Motor RCF (+/- 10%), CoG

Foundation stiffness / spring rates

Discharge head size

Discharge head type (TF, HF, etc)

Pressure rating (wall thickness, etc)

Pump Analysis


Design Standards

Required Modifications

Discharge head wall thickness

Ribs/gussets

Customer foundation

Possible lockout speed range


• Operating Speed Range From a hydraulic standpoint, 30% of the operating speed can be

considered a reasonable operating speed range Greater than 30% should allow for lockout speeds

The predicted lockout speed will be defined in a +/-20% range; however, the actual lockout typically only requires a +/-5% speed range to be avoided.

Need to avoid sub-synchronous whirl (below ground instability) Typically 30%-50% of maximum design speed Critical for pumps with hard bearings

Need to avoid second critical frequency Issues typically occur on high speed pumps with TF style discharge heads

• Separation Margin Minimum of separation factor above and below the running speed range is

standard for the reed critical analysis +/- 20% separation for speeds 1200 rpm and greater +25% / -20% separation for speeds 900 rpm and less

This is not a guaranteed factor or operating speed range

Pump Analysis


Design Standards


Pump Analysis


Flexible System (With Lockout Speeds)

Speed Speed

Operating Speed Range

Predicted

RCF Range

Actual

Blockout

Range


Pump Analysis


Flexible System (No Lockout Speeds)

Speed Speed


Predicted

RCF Range

Actual

Blockout

Range


Pump Analysis


Rigid System

Speed Speed


Predicted

RCF Range

Actual

Blockout

Range


• System frequency varies by: Motor manufacturer

Base Diameter

Frame Size

Weight

Center of Gravity

Reed Critical Frequency

Pump Analysis


Design Factors


• Cast Heads have limited use for VFD applications.

Cast heads always have a system natural frequency below the operating speed (flexible system)

Better for higher RPM applications (1800-3600rpm)

Not much can be done to stiffen the system

• 100% of Operating Speed Range

Must have system natural frequency higher than the operating speed (rigid system)

Requires proper selection of the motor to even be physically possible

Pump Analysis


Cases To Avoid


• A standard RCF analysis is only on the above ground portion

• Below ground analysis performed only on special case basis

Ex. Can pump, 35’ long, small pump size

Pump Analysis


Special Case



Pump Analysis

• Why is it done?

Limit deflection at the stuffing box

Reduce stresses in the discharge head


• Inputs Required:

Pump loading

Foundation design

Motor weight

Customer imposed loads


If the imposed reaction forces or

moments exceed the allowable load

When nozzle position differs from

standard (PRM)

Customer request

• Required Modifications:

Add ribs to the discharge head

Thicken the discharge head riser

More difficult to obtain higher loads on

TF style heads vs HF heads.

Discharges heads with 3-piece elbow

design.

Pumps in a flexible system


Pump Analysis

NOTES:



Pump Analysis

Why is it done?

Determines load imparted on foundation.

Allows proper sizing of anchor bolts, foundation, etc.



Pump Analysis

• Inputs required

Pump and motor weight

Nozzle loads

Pumpage weight

• Optional inputs

Start-up and locked rotor torque

Unrestrained piping

Motor imbalance

Other

• Required modifications

N/A – For reference only


Customer request


Seismic Calculations

Pump Analysis

• Why is it done?

System anchorage is designed to

withstand a seismic event

• Inputs required

Foundation loading (optional)

Specific design code (IBC is

standard)

Site seismic data

• Required Modifications

Anchor bolt size or quantity

Foundation (size, embedment,

strength)


Customer request

Example per IBC

Analyzed in X, Y, & Z directions


Anchor Bolt

Pump Analysis

Example per ACI

(American Concrete Institute)

• Why is it done?

System anchorage is designed to withstand operating loads

• Inputs required

Pump and motor weight

Nozzle loads

Pumpage weight


Anchor bolt size or quantity

Foundation (size, embedment, strength)


Customer request

When anchor bolts are supplied by Flowserve


Lifting Lug

Pump Analysis

• Why is it done?

To ensure the pump can be safely lifted using the provisions provided

• Inputs required

Pump weight

Discharge head style

Pump components (column size, etc)

Intended installation method (fully assembled, components, etc)


Lug redesign

Discharge head wall thickness


If Flowserve standards are exceeded

Weight and diameter dependent

Customer request


Torsional Analysis

Pump Analysis

• Why is it done?

Reduce induced torques and stresses

Prevent fatigue

• Inputs required

Motor inertia & stiffness


Shaft material change

Increase shaft size

Modify speed range


Customer request

When required by API 610


Lateral Analysis (Critical Speed)

Pump Analysis

• Why is it done?

Prevent displacement

Minimize vibration

• Inputs required

– Only pump data


Modify speed range

Change bearing material or

spacing


Flowserve standard

Optional analysis method

using FEA per customer

request.


Reed Critical Frequency vs Critical Speed

Pump Analysis

• Structural Analysis

Determines system frequency

based on combination of pump,

motor and foundation data.

Both above and below ground

frequencies exist

• Rotodynamic Analysis

Determines bearing spacing

Inputs from pump only

No impact from motor or

foundation

Reed Critical Frequency Analysis Critical Speed Analysis


Thermal Analysis

Pump Analysis

• Why is it done?

Predict temperature gradient

Determine pump growth rates and

total elongation

• Inputs required

– Ambient conditions

– Vendor temperature limits (motor,

coupling, etc)

– Cooling provisions

– Operational conditions (temperature

cycles)


– Custom design per application


– Applications > 260 C (500 F)

– Customer request

type vs1 and vs6 vertical turbine pumpscalgarypumpsymposium.ca/uploads/2013pdfs/design... ·...

Documents