Document Name: 0101r249

Section: TAPPI PRESS

Title: Process Control Fundamentals for thePulp & Paper Industry

TAPPI PRESS

Process Control Fundamentals for the Pulp and Paper IndustryBy Dr. Nancy J. Sell, Task Group Chair of the Process, Control, Electrical & Information Division

1995. 612 pp., 8-1/2" x 11" soft coverItem Number: 0101R249

ISBN: 0898522943

Table of Contents

Chapter 1: Introduction to Process Control1.1 Why Process Control?1.2 An Overview of the Technology

1.2.1 Common Control Configurations1.2.2 Control Hardware1.2.3 The Mathematics of FeedbackControl1.2.4 Control Technology Hierarchy

1.3 Historical Background1.4 Uniqueness of Pulp and PaperProcesses from a Control Perspective1.5 The Status of Control in the Pulp andPaper Industry

1.5.1 Control Loop Effectiveness1.5.2 Types of Control Technology1.5.3 Application of Control Loops

1.6 Important Control Concepts

Chapter 2: Summary of Conventional ProcessControl Concepts

2.1 Overview2.2 Modeling for Control

2.2.1 Types of Dynamic Processes2.2.2 Instantaneous or Steady-StateProcesses2.2.3 First-Order Lag2.2.4 Second-Order Processes2.2.5 Deadtime or Transport Delay2.2.6 Higher-Order Processes

2.3 Balances2.3.1 Mass and Energy2.3.2 Deviation from the Steady State

2.4 Laplace Transform2.4.1 Laplace Transforms of ImportantFunctions2.4.2 Final Value Theorem

2.4.3 Initial Value Theorem2.4.4 Laplace Transform of the DrivingForce2.4.5 Inverting the Transform

2.5 Solving the Dynamic Model2.5.1 Method of Partial Fractions

2.6 First-Order Response2.7 Transfer Function2.8 Gain2.9 Nonlinearity2.10 Linearization and Decoupling2.11 Second-Order Systems

2.11.1 Roots of the Second-OrderPolynomial

2.12 the Characteristic Equation2.13 Higher than Second-Order Systems2.14 Process Disturbances2.15 Summary of Process Dynamics2.16 Completing the Process Model

2.16.1 Feedback Control2.17 PID Controllers

2.17.1 Introduction to Controller Dynamics2.17.2 Basic Elements of PID Control2.17.3 Summary of PID Controls

2.18 Difficult Control Situations2.18.1 Controllers for Processes withDeadtime2.18.2 Feedforward Control2.18.3 Cascade Control

Chapter 3: Field Devices: Sensors andTransmitters

3.1 Introduction3.2 Brief History of the Evolution of FieldDevices3.3 Pressure Measurement

3.3.1 Mechanical Pressure MeasuringDevices3.3.2 Electrical Pressure Sensors3.3.3 Capillary and Other Filled SystemTemperature Sensors3.3.4 Installation of Temperature Sensors

3.4 Temperature Measurement3.4.1 Thermocouples3.4.2 Resistance Temperature Detectors(RTDs) and Thermistors3.4.3 Infrared Temperature Sensors3.4.4 Laser and Laser-CorrectedEmissivity Sensors3.4.5 Fiber Optic/Infrared TemperatureSensors3.4.6 Ultrasonic Temperature Sensors3.4.7 Filled Thermal Devices3.4.8 Miscellaneous Temperature Sensors

3.5 Flow Measurement3.5.1 Head Loss Flowmeters3.5.2 Electromagnetic Flowmeters3.5.3 Turbine Flowmeters3.5.4 Vortex Flowmeters3.5.5 Mass Flow (Coriolis Force)Flowmeters3.5.6 Ultrasonic Flowmeters3.5.7 Thermal Flowmeters3.5.8 Positive Displacement Flowmeters3.5.9 Target Flowmeters3.5.10 Optical Flowmeters3.5.11 Steam Flowmeters3.5.12 Solids Flow Flowmeters

3.6 Level Measurement3.6.1 Bubble Tube Level Devices3.6.2 Flanged Differential PressureDevices3.6.3 Ultrasonic Devices3.6.4 Nuclear Devices3.6.5 Capacitance Devices3.6.6 Radar and Microwave Devices

3.7 Common Miscellaneous Sensors3.7.1 pH Sensors3.7.2 Oxidation-Reduction Potential (ORP)Sensors3.7.3 Conductivity Sensors3.7.4 Consistency Sensors3.7.5 Brightness Sensors

3.8 Measurement Technique

Chapter 4: from Instrumentation toImplementation

4.1 Process Block Diagrams (PBDs)4.2 Process Flow Diagrams (PFDs)4.3 Process and Instrumentation Diagrams(PIDs)4.4 Instrumentation and Control Standards4.5 Loop Diagrams4.6 Instrument Index4.7 Final Control Elements

4.7.1 Valve Styles4.7.2 Globe Valves4.7.3 Ball Valves4.7.4 Butterfly Valves4.7.5 Plug Valves

4.8 Valve Connections4.8.1 Screw Connections4.8.2 Butt or Socket Connections4.8.3 Wafer Connections4.8.4 Flanged Connections

4.9 Valve Actuators4.9.1 Pneumatic and Hydraulic Actuators4.9.2 Electric Actuators4.9.3 Process-Based Actuators

4.10 Variable Speed Drive Systems4.10.1 DC Drives4.10.2 AC Drives

4.11 Drives Versus Valves in ControlApplications4.12 Miscellaneous Actuators

4.12.1 Linear Actuators4.12.2 Heaters

4.13 Automatic Control Valve Selection4.13.1 Determining Process Conditions4.13.2 Determining Pressure Drops AcrossValves4.13.3 Determining Valve FlowCharacteristics4.13.4 Choosing Valve Body Styles4.13.5 Determining Valve FlowCoefficients (C )V4.13.6 Selecting Proper Valve Sizes4.13.7 Selecting Proper ValveConstruction Materials

4.14 Hysteresis/Backlash/Stiction4.14.1 Hysteresis4.14.2 Backlash4.14.3 Stiction4.14.4 Result of Hysteresis, Backlash,Stiction

Chapter 5: Review of Control AnalysisTechniques

5.1 Introduction5.2 the Control Loop Analysis5.3 the Process Transfer Function

5.3.1 First-Order plus Deadtime5.3.2 Second-Order OverdampedResponse5.3.3 Integrating Process Response

5.4 Modeling Deadtime5.4.1 First-Order Taylor SeriesApproximation5.4.2 Pad Approximation

5.5 the Controller Transfer Function5.5.1 Sampled Data or Discrete Form5.5.2 Bump Test Method

5.6 Calculating the Loop Transfer Function5.7 Root Locus Analysis to Predict Closed-

Loop Behavior from the Loop TransferFunction

5.7.1 Rules for Interpreting Root LocusPlots5.7.2 Root Locus Examples5.7.3 Root Locus Manual Sketching Rules

5.8 Frequency Response Design Criteris -Gain and Phase Margin

5.8.1 Stability - Gain Margin, PhaseMargin, and the Bode Plot5.8.2 Robustness - Gain Margin, PhaseMargin, and the Bode Plot5.8.3 Stability and Robustness5.8.4 Setpoint Response and LoadResponse5.8.5 Robustness5.8.6 Robustness, Gain Margin, andPhase Margin Criteria

5.9 Calculation of the Setpoint Response5.10 Calculation of the Load Response5.11 Variability Analysis

5.11.1 the Nature of Noise andDisturbances5.11.2 Statistics and Variability5.11.3 Variability and the Power Spectrum5.11.4 the Period Plot5.11.5 Power Spectrum Log-Log Plot

5.12 Conclusion

Chapter 6: Controller Tuning Methods6.1 Introduction

6.1.1 Types of PID Algorithms6.1.2 Historical Methods of Loop Tuning6.1.3 Modern Tuning Methods (LambdaTuning)6.1.4 PID Tuning Procedures

6.2 Simple Models6.2.1 Obtaining Simple Models6.2.2 Determining P, I, and D Parameters6.2.3 Other Tuning Considerations

6.3 Specific Control Applications6.3.1 Tuning Flow Control Loops6.3.2 Tuning Temperature Control Loops6.3.3 Tuning Level Control Loops6.3.4 Tuning Control Loops for First OrderPlus Deadtime Processes (ConsistencyControl)6.3.5 Tuning Cascade Control Loops

Chapter 7: Control Objectives for Unifomity inPulp and Paper Manufacturing

7.1 Introduction7.1.1 Historical Perspective

7.2 Nature of Pulp and Paper ManufacturingProcess

7.2.1 Pulp and Paper Agitation and Mixing7.3 Process Related Variability and the Linkto End-Use Performance

7.3.1 Competitive Position

7.3.2 Old Concepts of Variability7.3.3 Process Variability Spectrum asSeen at the Paper Machine7.3.4 Very High Frequency Furnish Mix7.3.5 High Frequency ProcessDesign/Maintenance Problems7.3.6 Low Frequency Process ControlConsiderations and Problems7.3.7 Very Low Frequency Pulp and PaperTests

7.4 Sensors, Signal Filtering, andInterpretation

7.4.1 Digital Sampling and Aliasing7.4.2 Data Averaging7.4.3 Cross-Direction Data Points (DataBoxes)7.4.4 Single-Point (Fixed-Point) Data7.4.5 Scan-Average7.4.6 2-Sigma Variability Analysis

7.5 Control Loop Characteristics7.5.1 Closed-Loop Time Constant Lambda(7)7.5.2 Operational Motivation7.5.3 Generic Characteristics ofRegulatory Control Loops7.5.4 Loop Cut-Off Frequency7.5.5 Common Causes of Cycling andVariability7.5.6 Variability Impact of Control LoopTuning

7.6 Market Perspective - Variability AuditResults

7.6.1 Basis Weight Machine Direction(MD) variability7.6.2 Causes of Variability on the PaperMachine

7.7 Pulp Mill Variability and its Impact on thePaper Machine7.8 Paper Variability and ConvertingEquipment Runnability

7.8.1 Pressroom Operation7.8.2 Converting Operations7.8.3 Boxplants and Corrugators

7.9 Status of Control Loops in the NorthAmerican Pulp and Paper Industry

7.9.1 Control Technology7.9.2 Applications7.9.3 Control Algorithms7.9.4 Typical Process Variability7.9.5 Impact of Process Variability onProduct Uniformity7.9.6 Control Engineering and the HumanDimension7.9.7 Pulp and Paper Control EngineeringSkills

7.10 Old Tuning Methods and Their Legacy7.10.1 Fatal Flaws of the QuarterAmplitude damping method

7.11 Control Objectives for Pulp and Paper

Manufacturing7.11.1 Characteristics of the Pulp andPaper Control Environment7.11.2 Objectives for Robust Control ofSingle Loops

Chapter 8: Internal Model Control: a GeneralUnifying Concept

8.1 Introduction8.2 Historical Perspective8.3 Internal Model Control Structure8.4 Relationship Between IMC and StandardFeedback Control8.5 IMC Design Concept

8.5.1 Invertibility of Transfer Functions8.5.2 G Structuring RulesIMC

8.6 Examples of IMC Controllers and TheirStandard Feedback Equivalents

8.6.1 Pure Gain Process8.6.2 First-Order Process8.6.3 Second-Order Overdamped Process8.6.4 First-Order plus Deadtime

8.7 IMC-PID Tuning Rules8.7.1 Example of a Chip Bin Level ControlProblem8.7.2 Control Analysis8.7.3 Tuning Conclusion8.7.4 Handling a Noisy Signal

8.8 Implementation Issues - IMC vs.Conventional Control Structure8.9 Robustness

Chapter 9: Process Control Sample Problems9.1 Introduction9.2 Paper Machine Blend Chest Example

9.2.1 Dry Stock Blending9.2.2 Flow Control Tuning9.2.3 Flow Loops - Control Analysis - PineFlow FIC-1029.2.4 Blend Chest Level Controller Tuning9.2.5 Control Analysis - Level Control LIC-1009.2.6 Consistency Control Tuning9.2.7 Consistency - Control Analysis - PineConsistency NIC-1049.2.8 Ziegler-Nichols Tuning and ValveStiction9.2.9 Control Valve Dynamic Specification9.2.10 Level Noise and Other Results9.2.11 Conclusion

9.3 Mill Audit Example - Wet-End WhiteWater Header Pressure9.4 Control Engineering Quiz9.5 Mill Audit Examples - Chlorination StageBrightness Loop9.6 Control Engineering Quiz9.9 Mill Audit Example - Groundwood andStock Flow9.10 Control Engineering Quiz

9.11 Mill Audit Report - Diffusion WasherSeal Tank Levels9.12 Control Engineering Quiz9.13 Mill Audit Example - HeadboxSecondary Fan Pump Drive9.14 Control Engineering Quiz9.15 Mill Audit Example - Blend ChestConsistency Control9.16 Control Engineering Quiz9.17 Mill Audit Example - Brownstock FlowLoop9.18 Mill Audit Example - Total Head on aFine Paper Machine9.19 Control Engineering Quiz9.20 Mill Audit Example - "Smart"Transmitters and Digital Processing9.21 Control Engineering Quiz9.22 Mill Audit Example - Stock Tank Mixingand Agitation9.23 Control Engineering Quiz9.24 Mill Audit Example - Headbox Showersand Basis Weight Variability9.25 Control Engineering Quiz

Chapter 10: Control Design: Intuition orAnalysis?

10.1 Introduction10.2 the Blend System Process Design10.3 Control Design by Intuition10.4 Control Design by Analysis

10.4.1 Consistency10.4.2 Energy

10.5 Applications

Chapter 11: Beyond the Loop11.1 Introduction11.2 Convergent Evolution

11.2.1 Evolution of Control Technology11.2.2 Evolution of Control Algorithms11.2.3 Evolution of Database Technology11.2.4 Evolution of Other InformationBased Functions11.2.5 Evolution of Organizational Models11.2.6 Evolution of Architecture Models

11.3 Collision/Integration11.4 Justification11.5 Summary

Chapter 12: Distributed Control Systems12.1 Overview12.2 DCS Architecture

12.2.1 Distributed Control SystemComponents12.2.2 Types of DCS Highway Networks12.2.3 Local Area Networks12.2.4 Protocol12.2.5 LAN Speeds and Application12.2.6 Data Acquisition - Input and OutputDevices

12.2.7 Programmable Logic Controllers(PLCs)12.2.8 Smart Sensor MeasurementNetwork Interfaces12.2.9 Other Distributed Control Interfaces12.2.10 Controller Devices12.2.11 DCS Consoles and Work Stations12.2.12 Engineer's Work Station12.2.13 Peripheral Devices12.2.14 Distributed Control Service Tools

12.3 DCS Configuration12.3.1 DCS System Configuration12.3.2 DCS Controller Software12.3.3 Alarm Configuration12.3.4 Console Displays

12.4 Distributed Control and its Effect on MillOperations

Chapter 13: Process Optimization13.1 Introduction13.2 Definitions

13.2.1 Variables13.2.2 Model13.2.3 Objective Function13.2.4 Constraints13.2.5 Degrees of Freedom13.2.6 Math Program

13.3 Optimization Methods13.3.1 Analytical Methods13.3.2 Linearization13.3.3 Numerical Search Methods

13.4 Strategies and Examples13.4.1 Off-Line Optimization13.4.2 Real-Time Optimization

13.5 Summary

Chapter 14: Artificial Intelligence14.1 Definitions and Background14.2 Expert Systems

14.2.1 Background14.2.2 Problem Selection14.2.3 Structure14.2.4 Predicate Calculus14.2.5 Production Rules14.2.6 Frames and Scripts

14.3 Fuzzy Logic Control (FLC)14.3.1 Background14.3.2 Basic Concepts of Fuzzy LogicControl14.3.3 Fuzzy Logic Control Design14.3.4 Comments on the Use of FuzzyLogic14.3.5 Potential Applications of FuzzyLogic in the Pulp and Paper Industry14.3.6 an Example of Fuzzy ConsistencyControl14.3.7 Tuning the Fuzzy ConsistencyControl

14.4 Neural Network Systems

14.4.1 Background14.4.2 Training14.4.3 Input and Output Selection14.4.4 Hidden Nodes and Hidden Layers14.4.5 Accuracy14.4.6 Training Technique and ComputingTime14.4.7 Robustness14.4.8 Inferences and Generalizations

14.5 Combined Systems

Chapter 15: Economic Analysis andJustification

15.1 Introduction15.2 Financial Analysis Concepts

15.2.1 Depreciation15.2.2 Time Value of Money

15.3 Financial Analysis Methods15.3.1 Payback Period15.3.2 Net Present Value15.3.3 Internal Rate of Return15.3.4 Incremental Benefits

15.4 Process Areas15.4.1 Powerhouse Systems15.4.2 Woodyard15.4.3 Digesters15.4.4 Brown Stock Washers15.4.5 Bleach Plants15.4.6 Tower Level Control15.4.7 Paper Machines15.4.8 Coaters15.4.9 Supercalenders15.4.10 Roll Finishing and Shipping15.4.11 Information Systems15.4.12 Customer Information/Quality15.4.13 Continuous Improvement

15.5 Sample Economic Analysis Decision

Chapter 16: Case Study: the MWCS Project16.1 Introduction16.2 Project Description16.3 Corporate Background

16.3.1 Business Unit16.3.2 Technology Organization16.3.3 Corporate Engineering16.3.4 Management Information SystemsOrganization

16.4 Technology Transfer: Overcoming theBarriers

16.4.1 Credibility of the Technology16.4.2 Organizational Changes16.4.3 Perceived Benefits16.4.4 Consensus

16.5 Project Results16.5.1 Quantifiable Benefits16.5.2 Mill Ownership16.5.3 Team Building16.5.4 Mill-Resident TechnologyEngineers

16.5.5 Cultural Change16.6 Time Line16.7 Summary16.8 Conclusion

Chapter 17: the Marketplace and the Future17.1 Introduction17.2 Pulp and Paper Process Control - theCurrent Status

17.2.1 Steady State Thinking andVariability17.2.2 Lessons Learned from VariabilityAudits17.2.3 the Manufacturing Team17.2.4 Process Control Competence of theManufacturing Team17.2.5 Control Education and the ControlEngineer

17.3 A View from the Chemical Industry17.3.1 Focus on Quality and SPC in theChemical Industry17.3.2 Chemical Industry Algorithm Design- Trending Toward Generality17.3.3 The Chemical Industry's ControlStrategy Focus17.3.4 Process Design and ProcessControl in the Chemical Industry17.3.5 Process Control Education in theChemical Industry

17.4 Staffing, Organizations, and "Culture"17.4.1 Process Control Staffing Levels17.4.2 Organizations, Culture, and "Turf"17.4.3 Management Awareness

17.5 A View of the Future17.6 Conclusion

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