简介
A principal Objective of this courseware is to describe modem strategies for the design of chemical processes . processes . Since the early 1960s, the emphasis in undergraduate education has been on the engineering sciences . In recent years , however , more scientific approaches to process design have been developed , and the need to teach students these approaches has become widely recognized . Consequently , this courseware has been developed to help students and practitioners better utilize the modern approaches to process design . Like workers in thermodynamics ; momentum , heat , and mass transfer ; and chemical reaction kinetics , process designers apply the principles of chemistry , physics , and biology . Designers , however , utilize these principles , and those established by engineering scientists , to create industrial chemical processes that satisfy societal needs while returning a profit In so doing , designers emphasize the methods of synthesis and optimization in the face of uncertainties , often utilizing the results of analysis and experimentation prepared in cooper-ation with engineering scientists . In this courseware , the latest design strategies are described , most of which have been improved significantly with the advent of computers , mathematical programming methods , and artificial intelligence . Since most curricula place little emphasis on design strategies prior to design courses , this courseware is intended to provide a smooth transition for students and engineers who are called upon to design creative new processes . This courseware is intended for seniors and graduate students , most of whom have solved a few open-ended problems but have not received instruction in a systematic approach to process creation , the use of flowsheet simulators to assist in process design , and the application of economics in venture analysis . To provide this instruction , the subject matter is presented in five parts , which describe the various aspects of process design . As discussed in Chapter 1, Figure 1.1 shows how these parts relate to the entire design process and to each other . All of the parts are presented at the senior level . To comprehend much of Part Four, “Plantwide Controllability Assessment ,”it is necessary to have completed a course in process control , as discussed below . The emphasis throughout the text , and especially in Part One , on process invention , and part Two , on process synthesis , is on the steps in process creation and the development of a base-case design (s) . For the former , methods of tackling the primitive design problem , collecting data , and preparing the synthesis tree of alternative flowsheets are covered . Then , for the most promising flowsheets , a base-case design (s) is developed , including a detailed process flowsheet , with material and energy balances , The base-case design (s) then enters the detailed design stage , in which the equipment is sized , cost estimates are obtained , a profitability analysis is completed , and optimization is carried out , as discussed in Part Three. Throughout this courseware, various methods are utilized to perform the extensive calculations and provide graphical results that are visualized easily , including the use of computer programs of simulation and design optimization . The use of these programs is an important attribute of this courseware . We believe that our approach is an improvement over an alternative approach that introduces the strategies of process synthesis without computer methods , emphasizing heuristics and “back-of-the-envelope” calculations . We favor a blend of heuristics and analysis using the computer . Since the 1970s, many faculty have begun to augment the heuristic approach with an introducton to the analysis of prospective flowsheets using simulators , such as ASPEN PLUS ,HYSYS , PRO-II, CHEM-CAD . and FLOWTRAN . Today , most schools use one of these simulators , but often without adequate teaching materials . Consequently , the challenge for us , in the preparation of this courseware , has been to find the proper blend of modern computational approaches with simple heuristics . In the early chapters , especially , emphasis is placed on the synthesis of conventional chemical processes , that is , processes that operate at steady state and present no unusual control problems , Even for these processes , the new dynamic simulators are useful for studying start-up , shut-down , upsets , and the performance of alternative control systems . Dynamic analysis often suggests designs that are easier to implement and control . As processes become more integrated , to achieve more economical operation , their responses to disturbances and setpoint changes become more closely related to the design integration , and consequently , the need to assess their controllability gains importance . To introduce several methods , Part Four is intended for readers who have studied linear control theory for single-input , single-output (SISO) controllers (usually in a first course in process control ). Emphasis is placed on the methods for assessing the controllability of processes designed to operate at a steady state , with the consideration of frequency-dependent measures only when necessary . Controllers are designed for the most promising processes , and the most promising processes , and the ability of the processes to reject typical disturbances is evaluated using dynamic simulation . In summary , Part Four is intended to show that , to achieve more profitable designs , it is important to consider plantwide control during process design . This is accomplished using the simpler strategies for multiple-input, multiple-output (MIMO) control . A further Objective of this courseware is to illustrate the design strategies by applying them to chemical processes in several industries . Many are derived from the petrochemical industry , with much emphasis on environmental and safety considerations , including the reduction of sources of pollutants and hazardous wastes , and purification before streams are released into the environment . Several originate in the biochemicals indeustry , including fermentations to produce pharmaceuticals , foods , and chemicals . Others are involved in the manufacture of polymers and electronic materials . In addition to the processes interspersed n throughout the chapters , 31 design-problem statements , prepared by industrial prac-titioners , are provided in Appendix VIII . For each problem statement , a process design has been completed by groups of two of three students at the University of Pennsylvania . See also the report , “Process Design Projects at Penn: 100 Problem Statements , ” edited by W . D . Seider and Arnold Kivnick , which was circulated to faculty members around the world in 1994 .
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