Page 9 - Chemical engineering design

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5.8
Typical control systems
5.8.1 Level control CONTENTS 229
229
5.8.2 Pressure control 229
5.8.3 Flow control 229
5.8.4 Heat exchangers 230
5.8.5 Cascade control 231
5.8.6 Ratio control 231
5.8.7 Distillation column control 231
5.8.8 Reactor control 233
5.9 Alarms and safety trips, and interlocks 235
5.10 Computers and microprocessors in process control 236
5.11 References 238
5.12 Nomenclature 239
5.13 Problems 240
6 Costing and Project Evaluation 243
6.1 Introduction 243
6.2 Accuracy and purpose of capital cost estimates 243
6.3 Fixed and working capital 244
6.4 Cost escalation (inflation) 245
6.5 Rapid capital cost estimating methods 247
6.5.1 Historical costs 247
6.5.2 Step counting methods 249
6.6 The factorial method of cost estimation 250
6.6.1 Lang factors 251
6.6.2 Detailed factorial estimates 251
6.7 Estimation of purchased equipment costs 253
6.8 Summary of the factorial method 260
6.9 Operating costs 260
6.9.1 Estimation of operating costs 261
6.10 Economic evaluation of projects 270
6.10.1 Cash flow and cash-flow diagrams 270
6.10.2 Tax and depreciation 272
6.10.3 Discounted cash flow (time value of money) 272
6.10.4 Rate of return calculations 273
6.10.5 Discounted cash-flow rate of return (DCFRR) 273
6.10.6 Pay-back time 274
6.10.7 Allowing for inflation 274
6.10.8 Sensitivity analysis 274
6.10.9 Summary 275
6.11 Computer methods for costing and project evaluation 278
6.12 References 279
6.13 Nomenclature 279
6.14 Problems 280

7 Materials of Construction 284
7.1 Introduction 284
7.2 Material properties 284
7.3 Mechanical properties 285
7.3.1 Tensile strength 285
7.3.2 Stiffness 285
7.3.3 Toughness 286
7.3.4 Hardness 286
7.3.5 Fatigue 286
7.3.6 Creep 287
7.3.7 Effect of temperature on the mechanical properties 287
7.4 Corrosion resistance 287
7.4.1 Uniform corrosion 288
7.4.2 Galvanic corrosion 289