SECOND EDITION

PROCESS ENGINEERING and

DESIGN USING VISUAL BASIC®

ARUN DATTA

,A CRC Press*

J Taylor& Francis Group

^ Boca Raton London New York

CRC Press is an imprint of the

Taylor & Francis Croup, an informa business

Contents

Preface xxv

Acknowledgments xxvii

Author xxix

Chapter 1 Basic mathematics 1

Introduction 1

Physical constants 1

SI prefixes 1

Mensuration 1

Triangles 1

Rectangles 2

Parallelogram (opposite sides parallel) 2

Rhombus (equilateral parallelogram) 3

Trapezoid (four sides, two parallel) 3

Quadrilateral (four sided) 4

Regular polygon of n sides 4

Circle 4

Ellipse 6

Parabola 6

Prism 6

Pyramid 7

Right circular cylinder 7

Sphere 7

Right circular cone 8

Dished end 8

Irregular shape 8

Trapezoidal rule 8

Simpson's rule 8

Irregular volume 9

Algebra 9

Factoring 9

Arithmetic progression 9

Geometric progression 10

vii

viii Contents

Infinite series (in GP) 10

Best-fit straight line (least squares method) 10

Binomial equation 11

Polynomial equation 11

Maxima/minima 12

Cubic equation 13

General procedure 13

Matrix 16

Addition and multiplication of matrices 16

Addition of matrices 16

Multiplication of matrices 16

Matrix properties involving addition 17

Matrix properties involving multiplication 17

Matrix properties involving addition and

multiplication 18

Transpose 18

Symmetric matrix 18

Diagonal matrix 19

Determinants 19

Properties of determinants 19

Cofactor 21

Determinant and inverses 21

Adjoint 21Cramer's rule 22

Trigonometry 24

Functions of circular trigonometry 24

Periodic functions 25

Magic identity 25

Addition formulas 25

Double angle and half angle formulas 26

Product and sum formulas 27

Relations between angles and sides of triangles 28

Law of sines 28Law of tangents 28

Law of cosines 28Other relations 29

Inverse trigonometric functions 29

Hyperbolic functions 30

Other hyperbolic functions 31

Inverse hyperbolic functions 31

Analytical geometry 32

Straight line 32

Straight line through two points 32

Contents ix

Three points on one line 32

Circle 33

Tangent 33

Normal 33

Four points on a circle 34

Circle through three points 34

Conic section 35Focus 35

Eccentricity 35

Directrix 35

Partial derivatives 35

Parabola 36

Tangent line with a given slope, m 38

Ellipse 38

Hyperbola 40

Calculus 42

Differential calculus 42

Understanding the derivatives 43

Standard derivatives 44

Integral calculus 45

Volume of horizontal dished end 45

Volume of vertical dished end 47

Standard integrals 48

Differential equations 49

First-order differential equations 49

Separation of variables 50

Second-order differential equations 50

Bessel function 51

Partial differential equations 52

Laplace transform 59

Standard Laplace transforms 60

Fourier half-range expansions 61

Fourier half-range cosine series 61

Fourier half-range sine series 61

Numerical analysis 63

Solving linear equations (Newton's method) 63

Newton's method in two variables 64

Numerical methods in linear algebra 66

Gauss elimination 66

Cholesky method 67

Numerical integration 69

Trapezoidal rule 69

Simpson's rule 70

x Contents

Double integration using Simpson's rule 72Numerical solution of first-order differential equations 73

Euler's method 73

Improved Euler's method 73

Runge-Kutta method 74

Second-order differential equations 76

Runge-Kutta-Nystrom method 76Partial differential equations 77

Heat conduction problem 78

Numerical solution 79

Alternating direction implicit method 81

Unit conversions 86

Programming 86General notes for all programs 86Vessel 86

Program limitations 94Horizontal 95Data entry 95

Inclined 97Vertical 99

Conversion 100

Program limitations 101Procedure 101

References 102

Chapter 2 Thermodynamics 103Introduction 103

Heat, work, and energy 103

Force 103Kinetic and potential energy 104

First law of thermodynamics 104Phase rule 105Reversible process 105Heat content or enthalpy 106Heat capacity at constant volume and constant pressure 106

Isothermal process 107Adiabatic process 107

Equation of state 108

Boyle's law and Charles's law 108

Equation of state for real gas 110

Comparison between PR and SRK EOSs 110Acentric factor 110

Vapor pressure of pure components 112

Vapor pressure of water 115

Contents xi

Vapor pressure calculation using EOSs 116

Second law of thermodynamics 118

Carnot's cycle 119

Entropy 120

Sensible heat 121

Thermodynamic properties 122

Isobaric specific heat of hydrocarbon ideal gases 122

Isobaric specific heat of hydrocarbon real gases 124

Isobaric specific heat of hydrocarbon gas mixtures 126

Joule-Thomson coefficient 128

Isobaric specific heat of ideal liquids 131

Isobaric specific heat of real liquids 131

Enthalpy of gases 132

Enthalpy of gas mixtures 134

Entropy of ideal gases 137

Entropy of real gases 138

Fugacity correction 139

Entropy of hydrocarbon gas mixtures 140

Viscosities of ideal liquids 141

Viscosity of water 142

Viscosity of ideal hydrocarbon vapors 142

Liquid viscosity of defined mixtures at low pressure 142

Vapor viscosity of defined mixtures at low pressure 143

Thermal conductivity of pure hydrocarbon liquids at low

pressure 145

Thermal conductivity of pure hydrocarbon vapors at low

pressure 147

Flash calculation 148

Vapor-liquid equilibrium 148

Programming 150

Calculation of JT effect due to drop in pressure 150

Nomenclature 151

Greek characters 152

References 152

Chapter 3 Fluid mechanics 153

Introduction 153

Bernoulli's theorem 153

Velocity heads 155

Flow measurements 156

Orifice/Venturi meter 156

Thermal expansion factor (FJ 158

Coefficient of discharge (CD) 158

Orifice meter 158

xii Contents

Venturi meter 159

Expansion factor (Y) 159

Orifices 160

Nozzles and Venturi 160

Nonrecoverable pressure drop 160Orifices 160

Venturi with 15° divergent angle 160

Venturi with 7° divergent angle 160

Critical flow 161

Thickness of flow element 162

Thickness of restriction orifice 162

Area meter: Rotameters 165

Flow through an open channel 165

V notch 166

Rectangular notch 166

Frictional pressure drop 167

Darcy equation 167Flow in open channel 168

Estimation of friction factor 168

Friction factor: Laminar flow 168

Friction factor: Turbulent flow 169

Two-K method 169

K for reducer/expander 171

Reducer 171

Expander 171

Pipe entrance 172

Pipe exit 172

Split flow 172

Split 1,3 172

Split 1,2 172

Split 3,1 172

Split 1,2,3 173

Split 1,3,2 173

Split 3,1,2 173

Hydraulics: General guidelines 174

Roughness of pipe wall 174Control valve CV 174

Line sizing criteria for liquid lines 175Line sizing for gravity flow lines 176

Downpipe sizing 176

Line sizing criteria for vapor lines 177

Relief valve inlet line sizing 178

Relief valve outlet line sizing 178

Line sizing criteria for two-phase flow 178

Contents xiii

Hydraulics: Compressible fluids 179

Adiabatic flow in a pipe 179

Isothermal flow in a pipe 181

Heat loss 182

Types of cross-country buried pipelines 183

Yellow jacket 183

Coating thickness 183

Fusion-bonded epoxy coating 183

Rate of heat transfer 184

Film resistance (Rfilm) 184

Resistance of pipe (Rp,pe) • 186

Resistance of coatings (Rc0„„„s) 186

Resistance of environment (Rem) 187

Viscosity of water 189

Thermal conductivity of water 190

Viscosity of air 190

Thermal conductivity of air 190

Choked flow 190

Limiting differential pressure 191

Limiting expansion factor (V) 191

Hydraulics: Two-phase flow 193

Beggs and Brill correlations 195

Step 1: Estimation of flow regime 195

Step 2: Estimation of horizontal holdup 195

Step 3: Estimation of uphill holdup 196

Step 4: Estimation of downhill holdup 197

Step 5: Estimation of friction factor 197

Step 6: Estimation of pressure drop 197

Mukherjee and Brill correlations 198

Step 1: Estimation of flow regime 198

Step 2: Estimation of holdup 199

Step 3: Estimation of hydrostatic head 200

Step 4: Estimation of acceleration head 200

Step 5: Estimation of friction factor 201

Step 6: Estimation of frictional pressure drop 201

COz corrosion 203

CO, corrosion mechanism 203

NACE requirements 204

Rate of corrosion 204

NORSOK model 204

Corrosion 93 model 210

Corrosion 95 model 211

Programming 213

Program for flow elements 213

xiv Contents

General overview 213

Project details 214

Calculation form 214

Program limitations and notes 215

Program for hydraulic calculations 219

General overview 219

Project details 220

Program limitations and notes 221

Form incompressible fluid 221

Form compressible fluid 224

Pressure drop comparison 227

Form for two-phase flow 227

Program for corrosion calculations 230

General 231

NORSOK model 232

Calculation of pH: NORSOK model 232

Calculation of shear stress: NORSOK model 233

Corrosion 93/95 model 233

Nomenclature 236

Greek characters 239

References 240

Chapter 4 Heat transfer 243

Introduction 243

Conductive heat transfer 243

Heat conduction through a composite wall 244

Heat conduction through multiple cylindrical walls 245

Heat conduction through the wall of a sphere 247

Multidimensional steady-state heat conduction 248

Rectangular coordinates 248

Cylindrical coordinates 248

Spherical coordinates 248

Conduction shape factors 248

One-dimensional unsteady heat conduction 250

Rectangular coordinates 250

Cylindrical coordinates 250

Spherical coordinates 251

Thermal conductivity of various materials/components 256

Thermal conductivities of hydrocarbon liquids 256

Thermal conductivity of water (0-100°C) 264

Convective heat transfer 264

Free or natural convection 264

Free convection outside pipes and immersed body 264

Free convection to air 265

Contents xv

Heat-transfer coefficient for immersed bodies 266

Gas quenching 266

Forced convection 269

Forced convection inside the tube 269

Forced convection outside the tube 276

Shell-side cross flow area 276

Estimation of pressure drop 280

Shell-side pressure drop 280

Estimation of friction factor 281

Tube-side pressure drop 281

Log mean temperature difference 283

Overall heat-transfer coefficient 284

Fouling resistance 285

Extended surface 285

Fin efficiency 285

Longitudinal fins 290

Impact of heat-transfer coefficient on fin efficiency 291

Circular fins 291

Rectangular fins 292

Film coefficient for finned tube 292

Radiation heat transfer 293

Emissivity and absorptivity 293

Blackbody radiation 294

Emissivity of commonly used materials 294

Radiation shape factor 294

Parallel, equal rectangle 294

Parallel, equal, coaxial disks 296

Perpendicular rectangles with a common edge 297

Finite, coaxial cylinders 297

Parallel, coaxial disks 298

Radiation shield for large surface area 299

Double-pipe heat exchanger 303

Heat exchanger nomenclature 307

Standard tube pattern 308

Tube dimensions 308

Minimum unsupported tube span 310

Heat exchanger specification 315

Batch heating and cooling 315

Batch cooling, internal coil 318

Batch heating, internal coil 318

Batch cooling, counterflow external heat exchanger 318

Batch heating, counterflow external heat exchanger 319

Batch cooling, 1-2 multipass external heat exchanger 319

Batch heating, 1-2 multipass external heat exchanger 320

xvi Contents

Heat transfer in agitated vessels 320

Viscosity correction 321

Film coefficient inside the coil 322

Minimum metal temperature during depressuring operation 325

Programming 329

Program for double pipe heat exchanger 329

Program limitations and notes 329

Checking Example 4.10 (double-pipe exchanger) 329

Checking Example 4.11 (double-pipe finned exchanger) 329

Checking Example 4.13 (batch heating) 332

Checking Example 4.14 (batch cooling) 332

Nomenclature 334

Subscripts 335

Greek 335

References 336

Chapter 5 Distillation 337Introduction 337

Relative volatility 337

Vapor-liquid equilibrium 338

Raoult's law: Ideal solutions 339

Material balance for two-component systems 340

Operating lines 341

Reflux ratio 342

Minimum reflux ratio 342

Feed plate 343

McCabe-Thiele method 344

Smoker equations 346

Approximate column sizing 348

Sieve tray 348

Active hole area 350

Packed column 350

Tray efficiency 352

Murphree tray efficiencies 353

Overall column efficiency 353

Prediction of efficiency 355

Number of gas-phase transfer units 356

Number of liquid-phase transfer units 356

Mixing factor 356

Prediction of vapor diffusivity 358

Prediction of liquid diffusivity 358

Column hydraulics and design 362

Tray pressure drop 362

Sieve tray 362

Contents xvii

Dry pressure drop 363

Orifice coefficient (C0) 363

Weir liquid crest (how) 363

Residual head (hr) 364

Valve tray 365

Dry pressure drop 365

Downcomer design 367

Downcomer backup 367

Downcomer residence time 368

Flow regimes 369

Spray regime 369

Froth regime 369

Emulsion regime 369

Bubble regime 370

Pressure drop through packing 370

Estimation of pressure drop 370

Packing factor 371

Height equivalent to theoretical plate 373

Entrainment 374

Weeping and dumping 376

Programming 379

Program for Smoker equations 379

References 381

Chapter 6 Separators 383

Introduction 383

General principles of separation 383

Droplet in a vertical vessel 383

Droplet in a horizontal vessel 386

Gravity settling: Limiting conditions 386

Newton's law 387

Stokes' law 387

Intermediate law 387

Critical particle diameter 387

Vertical vs. horizontal separators 388

Advantages of the horizontal separator 389

Disadvantages of the horizontal separator 389

Advantages of the vertical separator 389

Disadvantages of the vertical separator 389

Design of a gas-liquid separator 389

Critical settling velocity 389

Design constant, KD 390

API 521 method 391

Design of liquid-liquid separators 392

xviii Contents

Mist eliminator 394

Wire mesh mist eliminator 394

Efficiency of the mist eliminator 394

Inertial parameter (K) 395

Maximum gas velocity 395

Corrected pad-specific surface area (SO) 395

Impaction efficiency factor (E) 396

Pressure drop of the mist eliminator 397

Vane-type mist eliminator 397

Efficiency of vane pack 398

Terminal centrifugal velocity 398

Pressure drop through the vane pack 398

General dimensions and setting of levels 399

The horizontal separator 399

Boot 402

Vertical separator 403

Separator internals 404

Inlet nozzle 404

Vortex breaker 405

Separator control 406

Pressure and flow control 406

Light liquid-level control 407

Heavy phase liquid-level and slug control 407

High-performance separator 407

Salient features of GLCC 408

Design parameters 409

Flow rates 409

Slug length 409

Density 411

Viscosity 411

Oil in gas droplet size 413

Oil in water droplet size 413

Water in oil droplet size 413

Inlet nozzle velocity 413

Gas outlet nozzle velocity 414

Liquid outlet velocity : 414

Separator program 414

Program limitations/notes 414

Horizontal separators 415

Three-phase flooded weir 415

Three-phase nonflooded-weir separator 415

Three phase with boot separator 415

Two-phase vapor-liquid separator 415

Two-phase liquid-liquid separator 415

Contents xix

Vertical separators 416

Two-phase vapor-liquid separator 416

Two-phase liquid-liquid separator 416

General overview of the separator.exe program 416

Design 421

Slug volume 421

Further checking and analysis 422

Design 423

Analysis 424

Nomenclature 425

Greek characters 426

References 427

Chapter 7 Overpressure protection 429

Introduction 429

Impact on plant design 429

Impact on individual design 429

Definition 430

Accumulation 430

Atmospheric discharge 431

Built-up back pressure 431

General back pressure 431

Superimposed back pressure 432

Balanced-bellows PRV 432

Blowdown 432

Closed discharge system 432

Cold differential test pressure 432

Conventional PRV 432

Design capacity 432

Design pressure 433

Maximum allowable accumulated pressure 433

Maximum allowable working pressure 433

Operating pressure 433

Overpressure 433

Pilot-operated PRV 434

Pressure relief valve 434

Pressure safety valve 434

Rated relieving capacity 434

Relief valve 434

Relieving conditions 434

Rupture disk 435

Safety relief valve 435

Safety valve 435

Set pressure 435

xx Contents

Vapor depressuring system 436

Vent stack 436

Types of pressure relief valves 436

Conventional pressure relief valve (vapor service) 436

Conventional pressure relief valve (liquid service) 438

Balanced-bellows pressure relief valve 439

Pilot-operated pressure relief valve 440

Rupture disk 443

Selection of pressure relief valves 445

Conventional pressure relief valve 445

Balanced-bellows pressure relief valve 445

Pilot-operated pressure relief valve 446

Rupture disk 446

PRV installation and line sizing 447

Compressors and pumps 447

Fired heaters 448

Heat exchangers 448

Piping 448

Pressure vessels 449

PRV isolation valves 449

Inlet piping to PRVs 451

Discharge piping from PRVs 453

Contingency quantification 454

General 454

Power failure 455

Local power failure 456

Failure of a distribution center 456

Total power failure 457

Cooling water failure 457

Instrument air failure 458

Steam failure 460

Total steam failure 460

Loss of steam to specific equipment 460

Partial steam failure 460

Check valve failure 460

Blocked outlet 461

Pump or compressor discharge 461

Multiple outlet 462

Block valve downstream of control valve 462

Control valve failure 462

Vapor breakthrough 463

Maximum flow 465

Thermal relief 465

Modulus of elasticity of pipe material (E) 468

Contents xxi

Coefficient of linear thermal expansion (a) 468

Valve leakage rate (q) 469

Compressibility of liquid (Z) 469

Coefficient of cubic expansion of liquids (f3) 469

Installation of thermal relief valve 471

Fire exposure 471

General guidelines 472

Estimation of wetted surface area 472

Fire circle 474

Estimation of latent heat and physical properties 474

Liquid wet vessel 475

Vessels with only gas 477

Two liquid phases 479

Heat exchanger tube rupture 480

Contingency calculation 482

Reflux failure and overhead system 484

Loss of reboiler heat 485

Venting of storage tanks 485

Venting due to liquid movements 486

Thermal venting 486

Fire exposure 486

Minimum flow area 488

Sizing procedure 489

Sizing of liquid relief 489

Sizing of vapor relief 491

Critical flow 491

Subcritical flow 492

Conventional and pilot-operated PRV 492

Balanced-bellows PRV 492

Sizing for steam relief 493

Sizing for two-phase fluids 494

Type 1 (omega method) 496

Type 2 (omega method) 499

Type 3 (integral method) 501

Design of flare stack 503

Minimum distance 504

Fraction of heat intensity transmitted (x) 504

Fraction of heat radiated (F) 505

Heat release (Q) 505

Sizing of a flare stack: Simple approach 505

Calculation of stack diameter 505

Calculation of flame length 506

Flame distortion caused by wind velocity 506

Sizing of flare stack: Brzustowski and Sommer approach 508

xxii Contents

Calculation of flare stack diameter 508

Location of flame center xc, yc 509

Lower explosive limit of mixtures 509Vertical distance (yj 511

Horizontal distance (xc) 511

SIL analysis 514

Definitions 515

Diagnostic coverage 515

Final element 515MooN 515

Programmable electronics 515

Programmable electronic system 515Protection layer 515

Safety-instrumented function 515

Safety-instrumented systems 516

Safety integrity 516

Safety integrity level 516

Safety life cycle 516Matrix for SIL determination 516

Probability of failure on demand 517ALARP model 519

Determination of SIL 519

Financial 521

Health and safety 522

Environment and asset 522

Programming 524

Program for pressure relief valve 524

Program limitations and notes 525

General overview 525

Project details 525

File save 526File open 526

File print 527Exit 527

Specific message or warning: back pressure 527

Back-pressure correction factor 527

Pilot-operated PRV 527

Liquid 528

Vapor 529

Two-phase type 1 calculation 529

Two-phase type 2 calculation 529

Two-phase type 3 calculation 529

Program for flare stack estimation 531

Program limitations and notes 531

Contents xxiii

Specific message/warning 532

Nomenclature 533

Greek characters 533

References 534

Chapter 8 Glycol dehydration 537

Introduction 537

Basic scheme 537

Advantages 539

Disadvantages 539

Pre-TEG coalescer 539

Contactor 539

Flash separator 540

Filters 540

Pumping 540

Glycol/glycol exchanger 541

Gas/glycol exchanger 541

Regenerator 541

Physical properties 542

Selection of type of glycol 542

Common properties of glycol 543

Densities of aqueous glycol solutions 543

Solubility of various compounds 543

Fire hazard information 543

Viscosities of aqueous glycol solutions 543

Specific heats of aqueous glycol solutions 543

Thermal conductivities of aqueous glycol solutions 543

Design aspects 544

Water content in hydrocarbon gas 544

Equilibrium dew point 545

Minimum lean-TEG concentration 548

Number of theoretical stages of the contactor 550

Design of contactor 551

Type of internals 554

Liquid distributor 562

Flash separator 563

Filters 564

Particulate filter 564

Carbon filter 564

Glycol/glycol exchanger 564

Gas/glycol exchanger 565

Regenerator 566

Still column 567

Reboiler 569

xxiv Contents

Fire tube heat density 569

Fire tube heat flux 570

Lean-glycol storage 570

Energy exchange pump 571

Burner management 573

Specifications 578

Programming 578

Program limitations 582

General overview 582File menu 582

Unit menu 583

Project details 584

Data entry 584

References 585

Index 587