The Motion Industry Meets the Process Industry

To Deliver Perfect Valve Control

Control Valve Performance

Does the Valve Move?Is the assembly capable of small control steps

over the range of useHow Fast Does the Valve Move?

Does the valve get to setpoint quickly when changes are made

Does the valve overshoot?How Stable is the Valve at Steady State?

Negative gradientsCavitation

Process Benchmarking - Variability

80% of control loops demonstrate excessiveprocess variability

30% due to control valve performance

The undesirable behavior of

control valves in the biggest contributor to

poor loop performance

Source: Entech---Resultsfrom audits of over 5000loops in Pulp & Paper Mills

Loops The Reason

Source ofVariability

Process Benchmarking

Servo Electric

Valve Actuation Technologies

HydraulicPneumatic Electric

Pneumatic Actuators

70% of the marketGood reliable actuationLow stiffnessLimited forcesWill overshoot/huntAir supply needed

Pneumatic Actuators

Pneumatic Positioners Guarantee that the

valve does in fact move to the right position

Used for better accuracyDiagnostics

Most are related to air

Hydraulic actuator

Very StiffFastHigh forcesVery energy inefficientHazardous fluidsTend to leak

Environmental problem

Difficult to maintain

Electric Actuator

Typically intermittent motorsCycled on and off For modulation, 3600

‘start’/hour needed

Uses physical limit switches to indicate valve closure/position

Position sensor potentiometer

Electric Actuator

Rotary to linear conversionWorm GearsBall screwsAcme screws

Not robust for high duty cyclesGear or ballscrew wearMotor burn-out

What If…..?

Electric actuator designed for modulating control Unaffected by valve stiction Perfect tracking of closed-loop controller

demand No dead time, lag, or overshootNo duty cycle (100% continuous torque)Fast responseLong life No maintenance

Motion Control Industry

Very precise positioningRapid repetitive motion (high duty cycles)High speedsLarge range of forcesHigh RepeatabilityHigh EfficiencyLow Maintenance

Design Criteria

Robustness to shock High speed High positioning

accuracy High response High mechanical

stiffness Moderate cost

High efficiency Very small size Low maintenance Completely sealed Rotary and Linear

designs Position Feedback

capable

Industrial Grade Electric Valve Actuator

Rotary to Linear Converter

Ball Screw TechnologyShort service lifeLow shock resistanceNearly impossible to clean and regreaseRotational speeds limited to ~ 1,000 rpmNoisyTricky disassembly

Rotary to Linear Converter

Roller screw TechnologyUp to 15x the travel life of a

(equivalent size) ball screwHigh Shock ResistanceEasy disassembly Easy cleaning and re-greasingRotational speeds up to 6,000

rpmDesign can be invertedQuiet operation

Ball Screw

Roller Screw

Roller Screws have Roller Screws have 15 times more contact area15 times more contact area

Load Points ( )

in the same spacesame space

Why Longer Travel Life?

Adjacent balls within a ball screw have conflicting friction leading to heating and wear.

Ball Screw

Roller ScrewRoller screw rollers are separated by journals.

Why More Efficient?

Why Higher Rotation Speeds?

Roller Screws

Ball ScrewsSharp turns of ball returns cause vibration and noise.

There is no loading and unloading of balls and no sharp turns of ball return tubes. Therefore, planetary roller screws operate efficiently up to 6,000 rpm.

Servo Motor vs Induction Motor

Small size High output relative to size and weight

AC induction motor 7.6in Brushless servo motor 3.5in

Closed loop feedbackResolver, Encoder, Hall effect

High efficiency (90%)All Voltages

24VDC to 460VAC

Servo Motor vs Induction Motor

High torque to inertia ratios Rapid acceleration

Reserve power (2x over continuous)

Cool runningcurrent draw proportional to load

QuietVibration free

Rotary Servo Motors

Very high torque densityHigh side load bearing designPlanetary Gear Reduction

Single and Double Reduction4:1 to 100:1

Digital Controller

Closed loop control of motorDigital/Analog feedbackPosition ControlForce (current) controlDiagnostics

Combining Technologies

ServoMotor

Inverted Roller Screw

Position Controller

Feedback

Linear

Combining Technologies

Rotary

Gear

ReductionFeedback

Position Controller

ServoMotor

Applying Technology to a Valve

Built in digital feedback

High Stiffness

Built in positioner

100% Torque at all times

Custom Valve Seat

High Repeatability

Extreme Accuracy

Fast Response

Fast Stroke

Sample Valve Applications

Forces up to 12,000 lbf

Torque up to 4600 lbf-in

Steam Turbine Application

Steam Turbine Retrofit

GE turbine steam controlDirect replacement of 10

inch diameter single acting, hydraulic cylinder

Elimination of mechanical governor operated pilot valve.

Servo actuator with a 10 inch stroke

Handwheel for manual operation

Turbine Fuel Valve Control Application

Steam Turbine Retrofit Nuclear Power Plant

Feedwater TurbineRack seating 6 valves1100 lbf peak3” cylinder with 6”

stroke85% efficientMuch Lower Routine

Maintenance Better performance

Pilot Valve Control Application

Steam Turbine RetrofitTurbine pilot valve

Linear Servo Actuator High static and dynamic

control accuracy Stiction and friction problems

eliminated Control valve's oscillation

was eliminated thereby extending steam distribution system's life, and reducing spare parts costs.

Gas Turbine Control

Inlet Guide Vanes Precise positioning and

feedbackAbility to fine tune injector

airflow to maintain CO and NOx emissions.

Bleed ValveVariable air bleed valves

and inlet bleed heat valves

Fuel Metering ValveBall valves

Cooling Water

Centrifugal Pipe Casting Molten iron is poured into a

water-cooled rotating pipe mold

Cooling water is precisely controlled by linear actuators on globe valves

Speed of response was critical

Aluminum Plate

Production of Aluminum for the aircraft and space markets

Application: Quenching of aluminum plates

Flow control of water, 35 to 85 psi, 280 to 875 gpm.

21 Ball Rotary Control Valves21 Servo electric actuatorsOriginal actuators had problems

with deadband and hunting-seeking behavior

Fuel Valves

Replacement of hydraulic actuators on gas valves for a gas turbine

18 servo actuators

Damper Applications

Low-NOx (nitrous oxide) burners need accurate air flow

Windbox Dampers44 electric linear servo actuators

4 or 8 ‘corners’ retrofittedReplaced failing electric ballscrew

actuators

Cement

Hopper Valve ControlOriginal actuator caused overfilling of

trucks due to response timeImproved ControlElimination of waste