finding the business value of basic control performance
DESCRIPTION
Finding the Business Value of Basic Control Performance The process industry is losing trillions of dollars because of underperforming control systems. These losses are measured in the form of lost production, energy, materials, safety, quality, and the environment. The underlying root cause of these losses is the failed performance of the mundane control loop. ExperTune / Metso Automation conference paper by George Buckbee at ISA Automation Conference 2013, Dammam, Saudi ArabiaTRANSCRIPT
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Finding the Business Valueof Basic Control Performance
George Buckbee, P.E.ExperTune, Inc.
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Presenter
• George Buckbee is General Manager of ExperTune Inc., a Metso Company. George holds a B.S. in Chemical Engineering from Washington University in St. Louis, and an M.S. in Chemical Engineering from the University of California at Santa Barbara. His 25+ years of industry experience have been focused in the field of process control. George is the author of several books, and dozens of articles. In 2011, George was selected as an ISA Fellow.
Finding the Business Value of Basic Control Performance
• Is There any Opportunity?• What Should We Do About It?• Fix It !• What Are the Results?
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Measure Decide Action
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Motivations:Typical Control System Performance
Typical Statistics• 10% - 90% Control Loops in Manual• 30% Loops-Tuning is completely wrong• 40% Loops Oscillating• Improper PID Loop Configuration
– 30% DCS Systems– 95% PID on PLC’s
• 85% Sub-Optimal Tuning• 75% Control Loops increase variability
We’ve Been Working Hardat the Wrong Things
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Schedule
Capital Cost
Replace in Kind
MinimizeImpact
More Security
Savings
Quality
IncreasedProduction
Safety & Environment
Energy &Sustainability
Costs
Controls Can Fail in Many Ways
Industrial Process
Sensor
Controlled Variables
Controllers Valve Stiction
Manipulated Variable
ExperTune solutions constantly monitor, diagnose and resolve issues with thousands of individual control loops from the loop level to the enterprise level
Sensor Fail
Excessive Noise
Oscillation
Temperature
Pressure
Composition
Flow
Disturbances
ActionFeedback
Valve Sizing
Hysteresis
Tuning
Interactions
ConfigurationErrors
Design Errors
ConstraintsNon-Linearity
Poor Dynamics
Equipment Diagnostics : Instrumentation
• Dead InstrumentPV Max = PV Min
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He’s dead, Jim.
Why Low Variability CountsPart 1
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Shahriari & Ding, IEEE 2011 Conference on Control Applications
Why Low Variability CountsPart 2
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Shahriari & Ding, IEEE 2011 Conference on Control Applications
Variability caused by Stiction
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Stiction in PCSA450 was a root cause for load disturbances throughout the Unit
Address the Root Cause
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• Is there still room for improvement?
Fixed Valve
Retune the Control Loop
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• There is still room for more improvement!
Re-Tuned
Oscillation in pH Control Reduces Reaction Efficiency
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Improper tuning leads to a 15s cycle in the caustic loop
Cycle in column pH eliminated when the tuning was changed
Why Monitoring of Control Performance?
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High variability indicates that the line is scaling and can no longer maintain the proper flow rate.
• The flow rate returns to normal after flushed with fresh water.
Line FlushHigh Variability Indicates Scaling
Decrease in ClO2 Consumption in Final Reaction Tower
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ClO2 flow rate has been reduced by approximately 50%
Savings = $170,000 / year
Monitoring –It’s Easier than Ever to Find the Issues
Osc – Valve – 59%
What if Variability Comes FromSomeplace Else?
Copyright 2011 ExperTune, Inc.
Finding the Root Cause of Interactions
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Where is it coming from?
Bone-dry weight.P66-2-133 is the 2nd Stage Cleaner Reject Pressure.
Consistency was too heavy and the cleaner rejects were plugging up and releasing at a regular cycle of 6 minutes
The Purpose of Control:Optimize the Process
• Drive Toward Optimum• Hold at Best Setpoint
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Energy & Production Rate Improvement
Conclusions
• Basic Controls are a Profit Center, not a Cost Center!• Reduced Variability Drives Efficiency• 24 x 7 Monitoring Identifies the Issues• Many Mechanisms to Achieve Savings:
– Valve Repairs– Instrumentation– Tuning– Mechanical Issues– Process Interaction
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23Thank You!
References
• “Process Variability and Inherent Efficiency Enhancement in Industrial Processes”, Shahrari, K. and Ding, F., IEEE International Conference on Control Applications, Denver, 2011
• “Control Stability Delivers Chemical Savings”, Mtkula, S., ISA Automation Week, Orlando, 2012
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