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1、 Donald R.Woods Rules of Thumb in Engineering Practice 18072007 Knowledge for Generations Each generation has its unique needs and aspirations. When Charles Wiley first opened his small printing shop in lower Manhattan in 1807, it was a generation of boundless potential searching for an identity. An
2、d we were there, helping to define a new American literary tradition. Over half a century later, in the midst of the Second Industrial Revolution, it was a generation focused on building the future. Once again, we were there, supplying the critical scientific, technical, and engineering knowledge th
3、at helped frame the world. Throughout the 20th Century, and into the new millennium, nations began to reach out beyond their own borders and a new international community was born. Wiley was there, expanding its operations around the world to enable a global exchange of ideas, opinions, and know-how
4、. For 200 years, Wiley has been an integral part of each generation s journey, en- abling the flow of information and understanding necessary to meet their needs and fulfill their aspirations. Today, bold new technologies are changing the way we live and learn. Wiley will be there, providing you the
5、 must-have knowledge you need to imagine new worlds, new possibilities, and new opportunities. Generations come and go, but you can always count on Wiley to provide you the knowledge you need, when and where you need it! William J. PescePeter Booth Wiley President and Chief Executive OfficerChairman
6、 of the Board Donald R.Woods Rules of Thumb in Engineering Practice The Author Prof. Donald R.Woods Chemical Engineering Department McMaster University Hamilton Ontaria Canada, L8S4L7 All books published by Wiley-VCH are care- fully produced. Nevertheless, authors, editors, and publisher do not warr
7、ant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illus- trations, procedural details or other items may inadvertently be inaccurate. Library of Congress Card No.: Applied for British Library Cataloguin
8、g-in-Publication Data: A catalogue record for this book is available from the British Library. Bibliographic information published by the Deutsche Nationalbibliothek Die Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbiblio- grafie; detailed bibliographic data are avail-
9、able in the Internet at . c 2007 WILEY-VCH Verlag GmbH 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, prob- lem solvers ask many What if? ques
10、tions. 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 th
11、umb. 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,
12、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
13、issues not usually considered in books Rules of Thumb in Engineering Practice. Donald R. Woods Copyright c 2007 WILEY-VCH Verlag GmbH and solidsolid 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
14、lesser-known equipment, such as prilling, flakers, electrostatic se- parators, 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 equip- ment. Wherever possible, for each piece of
15、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 ap- proximate capital cost including hard-to-locate installation factors; principles of good practice and approa
16、ches for trouble shooting. More specifically: x Area of Application: how or when to select: when would you use this piece of equipment? What is the usual available size range? x Guidelines: how to size: rules of thumb and short cut sizing for estimating the size of the equipment. In general these wo
17、rk within a factor of ten but usually a factor of four. x Capital 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 FO
18、B 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, 2.33. This means that values have been reported in this range and no recommended value is available at this time. The L+M* factor includes t
19、he 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, XVPreface 70s and 80
20、s 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
21、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 contractors fees and contingencies. x Good Practice: suggestions for good operability and suggestions for sustainability, waste minimization, s
22、afety and environmental concerns. x Trouble 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, foul- in
23、g* 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) som
24、etimes, with extru- ders, 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
25、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
26、 over time. Some are based on safety consid- erations; 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 ab
27、out 1 m s1; 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 st
28、eam was attached were much, much higher than if hot water was attached di- rectly 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 inf
29、ormation. 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 pres- ented in forms useful to the sizing, selecting and operation of the equipment. For XVIPreface example
30、, sizing maps, given for pumps, heat exchangers, columns and reactors, illustrate pictorially how different factors affect the decisions. For filtering centri- fuges, articles often describe which filtering centrifuge to select to handle slurries described by such qualitative terms as “fast filterin
31、g”, “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 exam- ple, relates “qualitative terms” to the “quantitative design parameters”. A similar synthesis and clar
32、ification 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 synthesi
33、zes and sum- marizes the values for these different applications. Corrosion, foam formation, stable emulsion formation and fouling are concerns that affect the successful op- eration of many different types of equipment. These concerns are addressed con- sistently, where needed, throughout the book.
34、 Interfacial and surface engineering aspects are included in the descriptions of pertinent unit operations. The selec- tion 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 dif- ferent types of
35、 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 pro- cessing equipment but effective engineers also need to communicate, work effec- tively in teams, solve problems and lead. Rules
36、 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 Engineer- ing Practice and Successful Trouble Shooting for Process Engineers
37、 and the section on Design that I coauthored in Marcel Dekkers “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 temp
38、erature, 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
39、phase systems, whether these are gas bubbles in liquids, sprays, a liquidliquid dispersion or a liquidsolid sys- tem. 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. Cha
40、pter 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, sy
41、stems thinking, process design, process improvement, trouble shooting and environmental and XVIIPreface safety issues. Rules of thumb are included about communication, listening, inter- personal skills, team work, performance review, leadership, intrepreneurship, en- trepreneurship, e-business and s
42、elf 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 gasliquid, liquidliquid and particulate systems. Chapter 2 considers equipment for transpo
43、rtation: 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
44、 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 liquidsolid separations, Section 5.5, and for solidsolid separations, Section 5.18. Chapter 6 starts with c
45、riteria for the selection of a reactor configuration. Data are given for sizing reactors. Then the details are given for over 30 reactor configura- tions. Chapter 7 considers mixing (of gases, liquids, mixtures and solids). Chapter 8 explores size reduction operations, such as foams, sprayers, emuls
46、ifica- tion, 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
47、 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
48、and Ted Tyler of Distillers 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, Queens University helped me im- mensely. They started me on my s
49、earch 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 Heste