appB Process Engineering Economics - James R. Couper

appB Process Engineering Economics - James R. Couper -...

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APPENDIX B Rules of Thumb 1 Although experienced engineers know where to find information and how to make accurate computations, they also keep a minimum body of information in mind on the ready, made up largely of shortcuts and rules of thumb. The present compilation may fit into such a minimum body of information, as a boost to the memory or extension in some instances into less often encountered areas. It is derived from the material in this book and is, in a sense, a digest of the book. An Engineering Rule of Thumb is an outright statement regarding suitable sizes or performance of equipment that obviates all need for extended calculations. Because any brief statements are subject to varying degrees of qualification, they are most safely applied by engineers who are substantially familiar with the topics. Nevertheless, such rules should be of value for 1 These Rules of Thumb were obtained from Stanley M. Walas’ book Chemical Process Equipment: Selection and Design (Woburn, MA: Butterworth, 1986). Permission was granted to reproduce this material. Butterworth is now part of Elsevier Science and Technical Publications. The following are additional references for Rules of Thumb 1. CR Branan. Rules of Thumb for Chemical Engineers. Houston, TX: Gulf Publishing Company, 1994. 2. D Woods. Process Design and Engineering Practice, Englewood Cliffs, NJ: Prentice Hall, 1995. 3. GD Ulrich, A Guide to Chemical Engineering Process Design and Economics, New York: Wiley, 1984. 4. WJ Korchinski, LE Turpin. Hydrocarbon Processing. January 1996: 129–133.
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approximate design and cost estimation, and should provide even the inexperienced engineer with perspective and a foundation whereby the reasonableness of detailed and computer-aided results can be appraised quickly, particularly on short notice such as in conference. Everyday activities also are governed to a large extent by rules of thumb. They serve us when we wish to take a course of action but are not in a position to find the best course of action. Of interest along this line is an amusing and often useful list of some 900 such digests of everyday experience that has been compiled by Parker ( Rules of Thumb , Houghton Mifflin, Boston, 1983). Much more can be stated in adequate summary fashion about some topics than about others, which accounts in part for the spottiness of the present coverage, but the spottiness also is due to ignorance and oversights on the part of the author. Accordingly, every engineer undoubtedly will supplement or modify this material in his own way. COMPRESSORS AND VACUUM PUMPS 1. Fans are used to raise the pressure about 3% (12 in. water), blowers raise to less than 40 psig, and compressors to higher pressures, although the blower range commonly is included in the compressor range.
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appB Process Engineering Economics - James R. Couper -...

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