Control of Batch Processes

Preface ix

1 Introduction 1

1.1. Categories of Processes 3

1.2. The Industry 5

1.3. The Ultimate Batch Process: The Kitchen in Your Home 13

1.4. Categories of Batch Processes 14

1.5. Automation Functions Required for Batch 18

1.6. Automation Equipment 26

Reference 30

2 Measurement Considerations 31

2.1. Temperature Measurement 32

2.2. Pressure Measurement 39

2.3. Weight and Level 47

2.4. Flow Measurements 61

2.5. Loss-in-Weight Application 67

References 72

3 Continuous Control Issues 73

3.1. Loops That Operate Intermittently 74

3.2. Emptying a Vessel 80

3.3. Terminating a Co-Feed 85

3.4. Adjusting Ratio Targets 89

3.5. Attaining Temperature Target for the Heel 97

3.6. Characterization Functions in Batch Applications 100

3.7. Scheduled Tuning in Batch Applications 101

3.8. Edge of the Envelope 104

3.9. No Flow Through Control Valve 107

3.10. No Pressure Drop across Control Valve 111

3.11. Attempting to Operate above a Process-Imposed Maximum 115

3.12. Attempting to Operate Below a Process-Imposed Minimum 121

3.13. Jacket Switching 124

3.14. Smooth Transitions between Heating and One Cooling Mode 129

3.15. Smooth Transitions between Two Cooling Modes 140

References 148

4 Discrete Devices 149

4.1. Discrete Inputs 149

4.2. Discrete Outputs 157

4.3. State Feedbacks 167

4.4. Associated Functions 176

4.5. Beyond Two-State Final Control Elements 182

5 Material Transfers 185

5.1. Multiple-Source, Single-Destination Material Transfer System 186

5.2. Single-Source, Multiple-Destination Material Transfer System 189

5.3. Multiple-Source, Multiple-Destination Material Transfer System 191

5.4. Validating a Material Transfer 194

5.5. Dribble Flow 197

5.6. Simultaneous Material Transfers 202

5.7. Drums 203

6 Structured Logic for Batch 205

6.1. Structured Programming 207

6.2. Product Recipes and Product Batches 212

6.3. Formula 215

6.4. Operations 216

6.5. Phases 220

6.6. Actions 223

References 226

7 Batch Unit or Process Unit 227

7.1. Defining a Batch Unit 228

7.2. Supporting Equipment 232

7.3. Step Programmer 237

7.4. Failure Considerations 241

7.5. Coordination 254

7.6. Shared Equipment: Exclusive Use 257

7.7. Shared Equipment: Limited Capacity 261

7.8. Identical Batch Units 262

8 Sequence Logic 265

8.1. Features Provided by Sequence Logic 265

8.2. Failure Monitoring and Response 267

8.3. Relay Ladder Diagrams 273

8.4. Procedural Languages 276

8.5. Special Languages 278

8.6. State Machine 280

8.7. Grafcet/Sequential Function Charts (SFCs) 283

9 Batches and Recipes 290

9.1. Organization of Recipes 291

9.2. Corporate Recipes 294

9.3. Executing Product Batches Simultaneously 299

9.4. Managing Product Batches 302

9.5. Executing Operations 305

9.6. Batch History Data 309

9.7. Performance Parameters 313

Index 319