02 BOPs / Woods D.R 2008 rules-of-thumb-in-Engineering-practice (epdf.tips)

XContents

9.5Size Enlargement: Solids: Spherical agglomeration 302

9.6Size Enlargement: Solids: Disc Agglomeration 302

9.7Size Enlargement: Solids: Drum Granulator 303

9.8Size Enlargement: Solids: Briquetting 303

9.9Size Enlargement: Solids: Tabletting 304

9.10Size Enlargement: Solids: Pelleting 304

9.11Solids: Modify Size and Shape: Extruders, Food Extruders,

	Pug Mills and Molding Machines 305
9.12	Solids: Solidify Liquid to Solid: Flakers, Belts and Prill Towers 323

9.13Coating 324

10	Process Vessels and Facilities 329

10.1Process Vessels 329

10.2Storage Vessels for Gases and Liquids 330

10.3Bins and Hoppers for Bulk Solids 330

10.4Bagging Machines 332

Appendix A: Units and Conversion of Units				334
Appendix B: Dimensionless Groups			361
Appendix C: Cox Charts – Vapor Pressures				374
Appendix D: Capital Cost Guidelines			376
D.1	Equipment Cost Correlations			376
D.2	Converting the FOB Cost into a Bare Module Cost					376
D.3	Converting FOB and L+M Costs into Total Fixed Capital
	Investment Costs	378
D.4	Detailed Equipment Cost Data Based on Equipment Type						378
	Section 1.4 Rules of Thumb about the Context for a Chemical Process:
	Process Control Sensors		379
	Section 2.1 Gas Moving: Pressure Service				380
	Section 2.2 Gas Moving: Vacuum Service				382
	Section 2.3 Liquid	383
	Section 2.4 Gas-Liquid (Two-phase Flow)				385
	Section 2.5 Pumping Slurries: Liquid–Solid Systems					385
	Section 2.6 Solids	385
	Section 2.7 Ducts and Pipes 387
	Section 3.1 Drives	387
	Section 3.2 Thermal Energy: Furnaces 388
	Section 3.3 Thermal Energy: Fluid Heat Exchangers,
	Condensers and Boilers		389
	Section 3.4 Thermal Energy: Fluidized Bed (Coils in Bed)						390
	Section 3.5 Thermal Energy: Static Mixers				390
	Section 3.6 Thermal Energy: Direct Contact L–L Immiscible Liquids 390

								Contents			XI
Section 3.7 Thermal Energy: Direct Contact G–L Cooling Towers											390
Section 3.8 Thermal Energy: Direct Contact G–L Quenchers									391
Section 3.9 Thermal Energy: Direct Contact G–L Condensers									391
Section 3.10 Thermal Energy: G–G Thermal Wheels and
Pebble Regenerators and Regenerators						391
Section 3.11 Thermal Energy: Refrigeration							391
Section 3.12 Thermal Energy: Steam Generation and Distribution											392
Section 3.13 High Temperature Heat Transfer Fluids 392
Section 3.14 Tempered Heat Exchange Systems								392
Section 4.1 Evaporation		392
Section 4.2 Distillation		393
Section 4.3 Freeze Concentration					395
Section 4.4 Melt Crystallization				396
Section 4.5 Zone Refining			396
Section 4.6 Solution Crystallization					396
Section 4.7 Precipitation		397
Section 4.8 Gas Absorption			397
Section 4.9 Gas Desorption/Stripping 397
Section 4.10 Solvent Extraction, SX					397
Section 4.11 Adsorption: Gas 399
Section 4.12 Adsorption: Liquid				399
Section 4.13 Ion Exchange			399
Section 4.14 Foam Fractionation 400
Section 4.15 Membranes and Membrane Configurations 400
Section 4.16 Membranes: Gas				400
Section 4.17 Membranes: Dialysis					400
Section 4.18 Membranes: Electrodialysis						400
Section 4.19 Membranes: Pervaporation						401
Section 4.20 Membranes: Reverse Osmosis, RO								401
Section 4.21 Membranes: Nanofiltration						401
Section 4.22 Membranes: Ultrafiltration, UF							401
Section 4.23 Microfiltration			401
Section 4.24 Chromatography				402
Section 5.1 Gas–Liquid		402
Section 5.2 Gas–Solid 402
Section 5.3 Liquid–Liquid			404
Section 5.3.1 Decanter		404
Section 5.3.2 Hydrocyclone			404
Section 5.3.3 Sedimentation Centrifuge						405
Section 5.4 Gas–Liquid–Liquid Separators 405
Section 5.5 Liquid–Solid: General Selection							405
Section 5.6 Dryers	405
Section 5.7 Screens for “Dewatering” 408
Section 5.8 Settlers	408
Section 5.9 Hydrocyclones			409
Section 5.10 Thickener		409

XII Contents

Section 5.11 CCD: Counter Current Decantation							410
Section 5.12 Sedimentation Centrifuges						410
Section 5.13 Filtering Centrifuge					410
Section 5.14 Filter	411
Section 5.15 Leacher		414
Section 5.16 Liquid–Solid: Dissolved Air Flotation, DAF								414
Section 5.17 Liquid–Solid: Expeller and Hydraulic Press								415
Section 5.18 Solid–Solid: General Selection 415
Section 5.19 Froth Flotation			415
Section 5.20 Electrostatic 415
Section 5.21 Magnetic		415
Section 5.22 Hydrocyclones			417
Section 5.23 Air Classifiers			417
Section 5.24 Rake Classifiers				417
Section 5.25 Spiral Classifiers				417
Section 5.26 Jig Concentrators				418
Section 5.27 Table Concentrators					418
Section 5.28 Sluice Concentrators					418
Section 5.29 Dense Media concentrators, DMS 418
Section 5.30 Screens		418
Sections 6.1 to 6.3 Consider Principles of Selecting Reactors									419
Section 6.4 Burner	418
Section 6.5 PFTR: Pipe/Tube, Empty Pipe for Fluid Systems									419
Section 6.6 PFTR: Static Mixer in Tube						420
Section 6.7 PFTR: Empty Pipe/Tube for Fluids and Solids 420
Section 6.8 PFTR: Empty Multitube, Nonadiabatic							420

Section 6.9 PFTR: Fixed Bed Catalyst in Tube or Vessel: Adiabatic 420
Section 6.10	PFTR: Multibed Adiabatic with Inter-bed
Quench or Heating 420
Section 6.11	PFTR: Fixed Bed with Radial Flow 421
Section 6.12	PFTR: Multitube Fixed Bed Catalyst

or Bed of Solid Inerts: Nonadiabatic			421
Section 6.13 PFTR: Bubble Reactor			421
Section 6.14 PFTR: Spray Reactor and Jet Nozzle Reactor 422
Section 6.15 PFTR: Trays 422
Section 6.16 PFTR: Packing 422
Section 6.17 PFTR: Trickle Bed		422
Section 6.18 PFTR: Monolithic		422
Section 6.19 PFTR: Thin Film		422
Section 6.20 PFTR: Scraped Surface Reactor				423
Section 6.21 PFTR: Multiple Hearth			423
Section 6.22 PFTR: Traveling Grate			423
Section 6.23	PFTR: Rotary Kiln	423
Section 6.24	PFTR, Shaft Furnace 423
Section 6.25	PFTR, Melting Cyclone Burner			424
Section 6.26	PFTR via Multistage CSTR 424

									Contents			XIII
Section 6.27 STR: Batch (Backmix)					424
Section 6.28 STR: Semibatch			425
Section 6.29 CSTR: Mechanical Mixer (Backmix)								425
Section 6.30 STR: Fluidized Bed (Backmix)						425
Section 6.31 TR: Tank Reactor				425
Section 6.32 Mix of CSTR, PFTR with Recycle							426
Section 6.33 STR: PFTR with Large Recycle						426
Section 6.34 Reaction Injection Molding and Reactive Extrusion											426
Section 6.35 Reactive Distillation, Extraction, Crystallization										427
Section 6.36 Membrane Reactors					427
Section 6.37 Liquid Piston Reactor					427
Section 7.1 Liquids	427
Section 7.2 Liquid–Liquid		428
Section 7.3 Liquid–Solid		428
Section 7.3.1 Solids Suspension				428
Section 7.3.2 Solids Dispersion				428
Section 7.3.3 Solids Dissolving				428
Section 7.3.4 Solids Flocculating 429
Section 7.4 Dry Solids 429
Section 8.1 Gas in Liquid (Foams)					429
Section 8.2 Liquid in Gas (Sprays)					430
Section 8.3 Liquid–Liquid		430
Section 8.4 Cell Disintegration				430
Section 8.5 Solids: Crushing and Grinding						430
Section 9.1 Size Enlargement: Liquid–Gas: Demisters 432
Section 9.2 Size Enlargement: Liquid–Liquid: Coalescers									432
Section 9.3 Size Enlargement: Solid in Liquid:
Coagulation/Flocculation		432
Section 9.4 Size Enlargement: Solids: Fluidization								432
Section 9.5 Size Enlargement: Solids: Spherical Agglomeration											432
Section 9.6 Size Enlargement: Solids: Disc Agglomeration 433
Section 9.7 Size Enlargement: Solids: Drum Granulator									433
Section 9.8 Size Enlargement: Solids: Briquetting								433
Section 9.9 Size Enlargement: Solids: Tabletting								433
Section 9.10 Size Enlargement: Solids: Pelleting								433
Section 9.11 Solids: Modify Size and Shape:
Extruders, Food Extruders, Pug Mills and Molding Machines										433
Section 9.12 Solids: Solidify Liquid to Solid:
Flakers, Belts and Prill towers				434
Section 9.13 Coating	434
Section 10.1 Process Vessels			434
Section 10.2 Storage Vessels for Gases and Liquids 435
Section 10.3 Bins and Hoppers for Bulk Solids							436
Section 10.4 Bagging Machines				436

Index 437

Preface

Brewster’s Dictionary of Phrase and Fable defines a rule of thumb as “a rough guestimate measure, practice or experience, as distinct from theory, in allusion to the use of the thumb for rough measurements. The first joint of the adult thumb measures almost exactly 1 inch (2.5 cm)”.

Engineers need such rules of thumb to guide decisions, set goals, check results and to help answer such questions as:

xWhen might I use something?

xHow do I obtain an approximate answer?

xHow might I obtain an approximate estimate of the cost?

xWhat is reasonable operating know-how?

xWhat might I do if something goes wrong?

Some believe that providing a collection of rules of thumb is dangerous – dangerous because engineers might forsake the fundamentals and place too much emphasis on order-of-magnitude estimates. However, I have found for problem solving in industry – for design, for process improvement and for trouble shooting – rules of thumb are not dangerous; they are essential. From research on problem solving, for example, we realize that skilled problem solvers create a rich internal representation of the problem. During the creation of that representation, problem solvers ask many What if? questions. They solve a simplified version of the problem. They approximate. Rules of thumb are needed to do this well. As we problem solve, research has found that we monitor our thought processes frequently; we check and double check often. To do this well requires us to have a rich set of rules of thumb. When we obtain an answer to a problem, skilled problem solvers check that the answer sounds reasonable and that it answers the initial problem. We use rules of thumb to do this. Rules of thumb are needed by working professionals.

This book is unique in its consistency in terminology and units, in its extensive cross referencing, in the range of process equipment considered, in the depth and breadth of coverage for each piece of equipment, in the coding of the source of the rule of thumb, in its synthesis of the information into convenient and easy- to-use formats and because it considers issues not usually considered in books

Rules of Thumb in Engineering Practice. Donald R. Woods

Copyright c 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

ISBN: 978-3-527-31220-7

Preface XV

about rules of thumb: career skills, how to function effectively and the people side of engineering.

This book is unique in its consistency in terminology and units. Tower or column? motionless mixer or static mixer? tray or plate?- these are just some of the terms that are used interchangeably when discussing process equipment. In this book consistent use of terms has been applied. The SI units of measurement are used throughout the text.

This book is unique in its extensive cross referencing. Some pieces of equipment are used for many different purposes. For example, fluidized beds are selected, sized and operated as heat exchangers, dryers, reactors, coaters and agglomerators. The details are given for each specific application with cross referencing to lead to other uses and rules of thumb. This cross referencing is included in each pertinent section and in the lengthy index.

This book is unique in the range of process equipment considered. Books on rules of thumb often focus on the familiar equipment: centrifugal pumps, shell and tube exchangers, and distillation columns, few consider solids processing equipment; and solid–solid separators are rarely discussed. In this book I have tried to consider an extremely broad range of over 350 types of equipment, especially some of the lesser-known equipment, such as prilling, flakers, electrostatic separators, magnetic separators, foam fractionation, expellers, zone refiners and multiple hearth furnaces.

This book is unique in the depth and breadth of coverage for each piece of equipment. Wherever possible, for each piece of equipment I have tried to include five dimensions important for the practising engineer: the area of application (or when to use a particular type of equipment); guidelines for sizing; an approximate capital cost including hard-to-locate installation factors; principles of good practice and approaches for trouble shooting. More specifically:

xArea of Application: how or when to select: when would you use this piece of equipment? What is the usual available size range?

xGuidelines: how to size: rules of thumb and short cut sizing for estimating the size of the equipment. In general these work within a factor of ten but usually a factor of four.

xCapital Cost Guidelines: Costs should be included with any rules of thumb because costs are such vital information to engineering practice. But these are guidelines – not data! The cost estimates given here are ball park ideas. The guideline FOB cost is in US $ for CEPCI = 1000. The L+M* factors are included because few published data are available. Some of these may be shown as a range, for example, 2.3–3. This means that values have been reported in this range and no recommended value is available at this time. The L+M* factor includes the FOB cost for carbon steel and excludes taxes, freight, delivery, duties and instruments, unless instruments are part of the package. The * is added to remind us that the instrumentation material and labor costs have been excluded, whereas most L+M values published in the 60s,

XVI Preface

70s and 80s included the instrumentation material and labor costs. The alloy corrections are given so that L+M for carbon steel can be reduced appropriately for the alloy used in the equipment. For some unit operations the equipment is built of concrete or is a lagoon. For such equipment the reported cost is the Physical Module, PM cost, or the FOB plus L+M* plus instruments plus taxes and duties. The cost excludes offsite, home office expense, field expense and contractor’s fees and contingencies.

xGood Practice: suggestions for good operability and suggestions for sustainability, waste minimization, safety and environmental concerns.

xTrouble Shooting: the symptom is given “Temperature i design” followed by a prioritized list of possible causes separated by “/”. Sometimes it is convenient to identify a cause and list, in turn, the sub-causes until the root cause is listed. For example, [ fouling]* might be listed as a “cause” but what causes the fouling? Fouling is not the root cause. Possible root causes are given in a separate listing under [Fouling]*. Such documentation is required because (i) we need to keep looking for causes until we find one that we can measure or change, and (ii) sometimes, with extruders, for example, the cause is because the temperature is too hot or too cold. We need guidance as to what is really the cause when the temperature is too hot and what is really the root cause when the temperature is too cold.

This book is unique because it attempts to code the source of the rule of thumb. This is important because not all rules of thumb arise from the same source. Some are a generalization of fundamentals, for example, the friction factor for turbulent flow is about 0.005; 1 kg of steam evaporates about 5 kg of organic. Such rules of thumb will not change over time. Some are based on safety considerations; these may change as we learn more about hazards and safe operation. Some are developed from an economic analysis, but as the relative costs change then the rule of thumb will change. For example, the “economic velocity” for pumping liquids is about 1 m s–1; but this will change as the relative costs of power, labor and materials change. Some rules of thumb are based on insurance policies, or the law. Such heuristics will change as policies and laws change. For example, in 1961 in the UK the insurance costs for a polymerizer to which live steam was attached were much, much higher than if hot water was attached directly to the vessel. So rules of thumb about good practice were developed in that industry to account for this. Coding is needed to remind us of the basis of the rule of thumb.

This book is unique in its synthesis of the information. This is not a convenient reproduction of material taken from different sources. Information from different sources is compared and contrasted, gaps are filled, and the information is presented in forms useful to the sizing, selecting and operation of the equipment. For

Preface XVII

example, sizing maps, given for pumps, heat exchangers, columns and reactors, illustrate pictorially how different factors affect the decisions. For filtering centrifuges, articles often describe which filtering centrifuge to select to handle slurries described by such qualitative terms as “fast filtering”, “medium filtering” and so on. But the quantitative design parameters for filtering centrifuges are the cake build-up rate, the intrinsic permeability and the particle size. Table 5.2, for example, relates “qualitative terms” to the “quantitative design parameters”. A similar synthesis and clarification is done, in Table 5.3, relating “qualitative” measures of filtration to such quantitative design parameters as rate of cake formation, filtrate rate, and cake resistance. The density-weighted velocity is important in sizing tray columns, KO pots, absorbers and demisters. Table 4.1 synthesizes and summarizes the values for these different applications. Corrosion, foam formation, stable emulsion formation and fouling are concerns that affect the successful operation of many different types of equipment. These concerns are addressed consistently, where needed, throughout the book. Interfacial and surface engineering aspects are included in the descriptions of pertinent unit operations. The selection criteria for reactors are synthesized in the series of tables in Chapter 6. Data are given for estimating the residence times in different reactors and for different types of reactions.

This book is unique because it considers issues not usually considered in books about rules of thumb. Most books and articles about rules of thumb focus on processing equipment but effective engineers also need to communicate, work effectively in teams, solve problems and lead. Rules of thumb are summarized for “systems” thinking and for “career skills” such as problem solving, creativity, leadership, entrepreneurship and e-business.

This book uses a format similar to my other books: Process Design and Engineering Practice and Successful Trouble Shooting for Process Engineers and the section on Design that I coauthored in Marcel Dekker’s “Handbook for Chemical Engineers” Another uniqueness is the information on residence times for reactions. Data from industrial reactors were used to create Figs. 6.5 to 6.7. These show how the residence time for reaction varies with temperature, phase and the heat of reaction. To my knowledge, this is the first time such an analysis has been presented in the open literature. Other detailed information is given on how

the type of reaction can be used to estimate the residence time.

Unique also is the extensive analysis of dispersed phase systems, whether these are gas bubbles in liquids, sprays, a liquid–liquid dispersion or a liquid–solid system. Characteristics of different contactors for such systems are summarized in Tables 1.1 to 1.3 and Figs. 1.1 and 1.2.

To aid in retrieving information, an extensive index is given.

Chapter 1 gives rules of thumb for physical and thermal properties, corrosion and process control; for engineering decisions related to batch versus continuous processing, the characteristics of heterogeneous phase contacting, economics, problem solving, goal setting, decision making, thermal pinch, systems thinking, process design, process improvement, trouble shooting and environmental and

XVIII Preface

safety issues. Rules of thumb are included about communication, listening, interpersonal skills, team work, performance review, leadership, intrepreneurship, entrepreneurship, e-business and self management. The section on heterogeneous phase contacting includes figures and tables that compare area/volume, oxygen transfer rates and other key characteristics of a wide range of contacting devices for gas–liquid, liquid–liquid and particulate systems.

Chapter 2 considers equipment for transportation: gases, liquids, fluid mixtures and solids

Chapter 3 addresses energy exchange equipment. This includes drives, motors and turbines as well as equipment for thermal energy exchange.

Chapter 4 describes equipment to separate homogeneous phases; these range from evaporators and distillation to membrane processes.

Chapter 5 focuses on equipment for the separation of heterogeneous phases. The chapter starts with a convenient general selection guide. More specific guides are given for liquid–solid separations, Section 5.5, and for solid–solid separations, Section 5.18.

Chapter 6 starts with criteria for the selection of a reactor configuration. Data are given for sizing reactors. Then the details are given for over 30 reactor configurations.

Chapter 7 considers mixing (of gases, liquids, mixtures and solids).

Chapter 8 explores size reduction operations, such as foams, sprayers, emulsification, crushing and grinding and cell disintegration.

Chapter 9 summarizes key information about equipment to increase or change the size of drops, bubbles and particles: demisters, coalescers, flocculators, spray dryers, fluidized beds, agglomeration, pelletizing, extrusion, flakers, prilling and coating.

Chapter 10 considers process and storage vessels, bins and hoppers and bagging machines.

This book is a synthesis and summary of experience I have gained since 1955. In the seven companies for whom I worked before coming to McMaster University, I learned much from the late Don Ormston and Ted Tyler of Distiller’s Company Ltd., Saltend, UK; Stan Chodkiewicz, Polysar, Sarnia, J.Mike F. Drake, British Geon Ltd., Barry, South Wales; Chuck Watson and the late Ed Crosby from the University of Wisconsin; the late Reg Clark, Queen’s University helped me immensely. They started me on my search for and synthesis of sound estimating procedures and guidelines for good judgment. I have received ongoing help from my colleagues at McMaster. In particular, the late R.B. Anderson, Archie Hamielec, Terry Hoffman, Cam Crowe, Joe Wright, Jim Dickson, Phil Wood, Les Shemilt, Marios Tsezos, Neil Bayes, Malcolm Baird, John Vlachopoulos, Raja Ghosh, the late Keith Murphy, Jack Norman, Tom Marlin, Bob Pelton, John Brash, Brian Ives, Gord Irons, W.K. Lu, Carlos Filipe and Doug Keller. Others who willingly shared their expertise and contributed to this book include Ken Hester, Rio Algom; Bob McAndrew and Glen Dobby, University of Toronto; G.S. Peter Castle and Maurice Bergougnou, University of Western Ontario;

Preface XIX

R.E. Edmunston and William K. Taylor, CIL Courtright, Ontario; Peter L. Silveston, University of Waterloo; Jud King and Scott Lynn, University of California, Berkeley; Ian Doig, University of New South Wales; Pierre Cote, Zenon Environmental; Doug R. Winter, Universal Gravo-plast, Toronto; V.I. Lakshmanan, Ontario Research Foundation, Sheridan Park; Ed Capes, NRC, Ottawa; Peter Clark, Epstein Engineering; Lyle Albright, Purdue University; Paul Belter, The Upjohn Co., Kalamazoo, MI; Jim Couper, University of Arkansas; Gary Powers and Art Westerberg, Carnegie Mellon University; John C. Berg, University of Washington; Jim Douglas, University of Massachusetts; Bill Cotton, Dupont of Canada, Ltd; Kingston; Jesse Shen, East China University for Science and Technology, Shanghai; Emil Nenninger, Hatch and Associates; Graham Davies, UMIST, UK; Don Dahlstrom, University of Utah, Vince Grassi, Air Products and Chemicals Inc., Allentown, PA; Barry Jackson, Queen’s University, Kingston; John Bell, of Waterdown; Chip Howat, University of Kansas; Andrew Douglas, Bartek Chemicals, Stoney Creek, ON; Darsh Wasan, IIT; Craig Boogers, T.H. Solutions, Inc., Burlington; Doug C. Pearson, DDC Technical Consulting, Parry Sound; Luis J. Rodriguez, Downstream Oil Company, Waterdown and Ken Higginson, Waterdown. Special thanks to Murray Moo-Young, University of Waterloo and Jack Hopper, Lamar University, Beaumont, TX for their input on reactors. I appreciate the feedback from the students at McMaster University, class of 2006.

Don Woods, Waterdown, January 2006