The Motion Industry Meets the Process Industry

1
The Motion Industry Meets the Process Industry

• To Deliver Perfect Valve Control

2
Control Valve Performance

• Does the Valve Move?
• Is the assembly capable of small control steps
  over the range of use
• How 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 gradients
• Cavitation

3
Process Benchmarking - Variability
Loops
The Reason
The undesirable behavior of control valves in the
biggest contributor to poor loop performance
Source of Variability

• 80 of control loops demonstrate
  excessiveprocess variability
• 30 due to control valve performance

4
Process Benchmarking
5
Valve Actuation Technologies
Electric
Servo Electric
Hydraulic
6
Pneumatic Actuators

• 70 of the market
• Good reliable actuation
• Low stiffness
• Limited forces
• Will overshoot/hunt
• Air supply needed

7
Pneumatic Actuators

• Pneumatic Positioners
• Guarantee that the valve does in fact move to
  the right position
• Used for better accuracy
• Diagnostics
• Most are related to air

8
Hydraulic actuator

• Very Stiff
• Fast
• High forces
• Very energy inefficient
• Hazardous fluids
• Tend to leak
• Environmental problem
• Difficult to maintain

9
Electric Actuator

• Typically intermittent motors
• Cycled on and off
• For modulation, 3600 start/hour needed
• Uses physical limit switches to indicate valve
  closure/position
• Position sensor
• potentiometer

10
Electric Actuator

• Rotary to linear conversion
• Worm Gears
• Ball screws
• Acme screws
• Not robust for high duty cycles
• Gear or ballscrew wear
• Motor burn-out

11
What If..?

• Electric actuator designed for modulating control
  
• Unaffected by valve stiction
• Perfect tracking of closed-loop controller
  demand
• No dead time, lag, or overshoot
• No duty cycle (100 continuous torque)
• Fast response
• Long life
• No maintenance

12
Motion Control Industry

• Very precise positioning
• Rapid repetitive motion (high duty cycles)
• High speeds
• Large range of forces
• High Repeatability
• High Efficiency
• Low Maintenance

13
Design Criteria
Industrial Grade Electric Valve Actuator

• 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

14
Rotary to Linear Converter

• Ball Screw Technology
• Short service life
• Low shock resistance
• Nearly impossible to clean and regrease
• Rotational speeds limited to 1,000 rpm
• Noisy
• Tricky disassembly

15
Rotary to Linear Converter

• Roller screw Technology
• Up to 15x the travel life of a (equivalent size)
  ball screw
• High Shock Resistance
• Easy disassembly
• Easy cleaning and re-greasing
• Rotational speeds up to 6,000 rpm
• Design can be inverted
• Quiet operation

16
Why Longer Travel Life?
Ball Screw
Roller Screws have 15 times more contact area
in the same space
Roller Screw
Load Points ( )
17
Why More Efficient?
Roller Screw
Roller screw rollers are separated by journals.
Ball Screw
Adjacent balls within a ball screw have
conflicting friction leading to heating and wear.
18
Why Higher Rotation Speeds?

• Roller Screws

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.
Ball Screws
Sharp turns of ball returns cause vibration and
noise.
19
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 feedback
• Resolver, Encoder, Hall effect
• High efficiency (90)
• All Voltages
• 24VDC to 460VAC

20
Servo Motor vs Induction Motor

• High torque to inertia ratios
• Rapid acceleration
• Reserve power
• (2x over continuous)
• Cool running
• current draw proportional to load
• Quiet
• Vibration free

21
Rotary Servo Motors

• Very high torque density
• High side load bearing design
• Planetary Gear Reduction
• Single and Double Reduction
• 41 to 1001

22
Digital Controller

• Closed loop control of motor
• Digital/Analog feedback
• Position Control
• Force (current) control
• Diagnostics

23
Combining Technologies
Linear
ServoMotor
Position Controller
Inverted Roller Screw
Feedback
24
Combining Technologies
Rotary
ServoMotor
Position Controller
Gear Reduction
Feedback
25
Applying Technology to a Valve
Built in positioner
Built in digital feedback
100 Torque at all times
High Stiffness
High Repeatability
Fast Response
Extreme Accuracy
Fast Stroke
Custom Valve Seat
26
Sample Valve Applications
Forces up to 12,000 lbf Torque up to 4600 lbf-in
27
Steam Turbine Application

• Steam Turbine Retrofit
• GE turbine steam control
• Direct 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

28
Turbine Fuel Valve Control Application

• Steam Turbine Retrofit
• Nuclear Power Plant Feedwater Turbine
• Rack seating 6 valves
• 1100 lbf peak
• 3 cylinder with 6 stroke
• 85 efficient
• Much Lower Routine Maintenance
• Better performance

29
Pilot Valve Control Application

• Steam Turbine Retrofit
• Turbine 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.

30
Gas Turbine Control

• Inlet Guide Vanes
• Precise positioning and feedback
• Ability to fine tune injector airflow to maintain
  CO and NOx emissions.
• Bleed Valve
• Variable air bleed valves and inlet bleed heat
  valves
• Fuel Metering Valve
• Ball valves

31
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

32
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 Valves
• 21 Servo electric actuators
• Original actuators had problems with deadband and
  hunting-seeking behavior

33
Fuel Valves

• Replacement of hydraulic actuators on gas valves
  for a gas turbine
• 18 servo actuators

34
Damper Applications

• Low-NOx (nitrous oxide) burners need accurate
  air flow
• Windbox Dampers
• 44 electric linear servo actuators
• 4 or 8 corners retrofitted
• Replaced failing electric ballscrew actuators

35
Cement

• Hopper Valve Control
• Original actuator caused overfilling of trucks
  due to response time
• Improved Control
• Elimination of waste