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Education in process systems engineering: past, present and future
Computers and Chemical Engineering 26 (2002) 283– 293 www.elsevier.com/locate/compchemeng
Education in process systems engineering: past, present and future John Perkins * Department of Chemical Engineering and Chemical Technology, Center for Process Systems Engineering, Imperial College of Science, Technology and Medicine, London SW 7 2BY, UK Received 16 August 2000; received in revised form 27 November 2000; accepted 27 November 2000
Abstract The term ‘Process Systems Engineering’ may be traced back at least as far as the early 1960s. In parallel with the emergence of a research agenda for this new sub-discipline, pioneers of the subject began to consider the nature of education in process systems engineering, and its relationship to the broader chemical engineering curriculum. In this paper, a personal view of the history of the development of education in our field will be given. It will be argued that two complementary approaches have been pursued, each of which has played an important role both within the sub-discipline itself and in the context of the development of chemical engineering education more broadly. On the one hand, pedagogical materials have been developed and courses delivered covering important advances in process systems engineering as they have emerged from the research community. As a result, the teaching of design and control methodologies, techniques and tools has become more systematic and comprehensive in the past four decades, reflecting the strides made by the research community in tackling these complex engineering problems. In parallel with these developments, educators have been concerned to develop curricula and courses designed to help students to adopt a ‘systems approach’ to engineering problem solving. Here, the objective has been not so much to help students to learn about the application of specific ideas and methods to particular classes of engineering problem. Rather the aim has been to encourage students to adopt a particular, systematic approach to their entire professional practice. Advances in both directions will be illustrated through examples taken from the literature, as well as through an account of the process systems engineering components of the chemical engineering course at Imperial College. Finally, the author will present his personal view on developments which are likely to emerge in the future, as process systems engineering and chemical engineering continue to respond to external changes as well as to the continuing development of our subject. © 2002 Published by Elsevier Science Ltd. Keywords: Process systems engineering; Education; Chemical engineering
1. Introduction The Process Systems Engineering conference series was inaugurated in 1982, at the initiative of Professor Takeichiro Takamatsu, then of Kyoto University. However, the term ‘systems engineering’ has a much longer history, and by the early 1960s a number of chemical engineers had recognised the opportunities to develop systems concepts appropriate to the practice of their profession. As early as 1959, T.J. Williams, at that time an employee of the Monsanto company, used the opportunity provided by an invitation from the Univer* Tel.: +44-207-589-5111. E-mail address: [email protected] (J. Perkins).
sity of Texas to deliver the Schoch lectures for that year to present his impressively broad vision of Systems Engineering for the Process Industries (Williams, 1961). Huckaba and Monet (1963) in the Foreword to a CEP Symposium Series volume, entitled Process Systems Engineering and published in 1963, stated that: ‘‘Chemical engineers are primarily interested in process systems engineering in which the systems approach is employed in the design and operation of chemical processing plants.’’
In the same year, we find in the text of the Inaugural Lecture of Roger Sargent as Professor of Chemical Engineering at Imperial College (Sargent, 1963):
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‘‘…broad consideration of the interaction between the performance of individual units and the requirements of the process has always been a feature of good process design, but in recent years it has become fashionable to refer to this as ‘optimisation’, and it has even come to be regarded as a new, separate branch of engineering, known as ‘systems engineering’. However, new names rarely appear without good cause and in this field the advent of automatic computers has given rise to a whole range of techniques which have revolutionised the approach here …’’
It is not the purpose of this paper to trace the history of the development of process systems engineering. Our goal will be to seek to map changes in the education of students of chemical engineering, which have resulted from the emergence of process systems engineering concepts in the past four decades or so. It will be argued that there are two strands to these developments. On the one hand, pedagogical materials have been developed and courses delivered covering important advances in process systems engineering as they have emerged from the research community. In tracing these developments, a method used by Freshwater (1989) to trace the development of the conceptual basis of chemical engineering itself will be employed, viz. the analysis of key textbooks. Inevitably, in a paper of this length, it will not be possible to give a comprehensive review. Nor will such a review be necessary for our purposes. Rather, we shall focus on what seem to be some of the pioneering contributions (restricted to those published in English) in order to investigate the emergence of the major themes in process systems engineering education. The second strand of educational development concerns curricula and courses designed to help students to acquire and adopt a ‘systems approach’ to engineering problem solving. While there are much broader questions involved in pursuing the educational objectives associated with this strand, and the issues extend well beyond the boundaries of process systems engineering, nevertheless process systems engineers have made pioneering developments here also. Indeed, there is some evidence that the desire to help students to develop the skills needed to tackle complex engineering problems partly motivated the early research in process systems engineering.
2. Historical developments-techniques and tools Process Systems Engineering is concerned with the development of techniques and tools to address the generic manufacturing problems of design, operation
and control for the process industries. In tracing the pedagogical developments in the field, it will be convenient to consider control and design separately, since these topics have tended to appear in curricula as separate courses.
2.1. Process control Compulsory courses in process control can be found in the undergraduate curriculum of some departments as early as 1950 (e.g. Shemilt, 1980) and textbooks on the subject were published in that decade. One of the early textbooks to appear, first published in 1955, was A.J. Young’s An Introduction to Process Control System Design (Young, 1955). Young was an employee of ICI, who in 1946 had been given the responsibility of setting up what became the Central Instrument Laboratory of that company. The book reflects the long-standing concerns of industrial process control engineers keen to promote the benefits of their technology. To quote from the Preface to the book: ‘‘The first necessity at the present time is to ensure that the most economic use is made of existing knowledge and equipment. The second is to show plant designers that the full benefits of automatic control cannot be enjoyed without their co-operation, and to obtain their co-operation’’ (Young, 1955).
Chapter 1 of the book is entitled ‘Economics’ and discusses in some detail the benefits that may be expected through the application of appropriate automatic control technology in the process industries. A treatment of the characteristics of control loops and of plant dynamics is followed by a chapter on ‘Plant Controllability’ (chapter 5), which is defined by Young as ‘the ease or difficulty of controlling a plant’. In subsequent chapters, it is shown how frequency response methods may be used to quantify controllability, as well as to set up appropriate process control systems. In the year following the publication of Young’s book, Norman Ceaglske, a Professor of chemical engineering at the University of Minnesota, published Automatic Process Control for Chemical Engineers, a textbook based on an elementary course taught to undergraduates at that university (Ceaglske, 1956). After a short introductory section describing in qualitative terms the components of process control systems, the remainder of the book is concerned with mathematical techniques for the analysis of simple control systems. While being somewhat narrow in its focus, this book appears to represent the first academic text in process control specifically designed for chemical engineering undergraduates.
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Another pioneering book produced within in an industrial context is Page Buckley’s Techniques of Process Control, published in 1964 (Buckley, 1964). Buckley had extensive industrial experience as a process control engineer with Du Pont. In the Preface to his book, Buckley is at great pains to emphasise the synthetic nature of process control: ‘‘…we are not so much interested in knowing precisely how a system behaves as we are in knowing how to design it so that it will operate satisfactorily. In other words, we are primarily interested in synthesis rather than analysis, in logic rather than computation.’’
After a review of developments in control up to 1964, the book deals first with the Mathematics of Process Control (Laplace and z-transformations, frequency response, block diagram algebra, and linearisation methods). The following section on Process Control Theory includes an important chapter on Overall Process Control as well as discussion of more traditional topics such as Stability, Sampled Data and Distributed Systems. Three more sections deal with the dynamics and control of the important process operations of fluid flow, heat transfer and distillation. Throughout the book, theory is used to help decide the important structural questions associated with the synthesis of process control systems. Although both of the ‘industrial’ books discussed above represent pioneering efforts to codify the subject, their presentation probably made their adoption as the basis of first courses in process control somewhat impractical. Indeed it is clear that the authors themselves considered practitioners rather than undergraduate students as their prime audience. By the 1960s, a clear need had emerged to provide undergraduate texts in the subject to serve the growing number of departments around the world keen to incorporate process control into their core curriculum. Nineteen sixty-five saw the publication of a book that was to dominate the field for what was, in retrospect, a surprising length of time, Process Systems Analysis and Control by Coughanowr and Koppel (1965). The book was developed from the required senior course, which had been given at Purdue University since 1960. In contrast to the books of Young and of Buckley, the focus of Coughanowr and Koppel is on the analysis of process and control system dynamics. Of the book’s 32 chapters, only one (chapter 23) deals with process applications, illustrating the issues faced in the implementation of complex process control systems through a discussion of distillation column control. A survey of process control education in North America in 1978 (Seborg, 1980) showed that of the 135 schools which responded to the survey, 69 were using
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Coughanowr and Koppel’s book for their undergraduate control teaching, and a further seven for graduate level teaching. Luyben’s book (1974), published 4 years before the survey was conducted, had the second largest number of entries with 21. Again, the emphasis of the book was on analysis with a very short section of six pages devoted to control-systems design concepts). In hindsight, this dichotomy between the analytical treatment of the subject in the most popular university texts, and the published writings of industrial process control practitioners placing great emphasis on synthetic issues is quite striking. In the last two decades, textbooks providing a balance between analysis and synthesis of process control systems have appeared. Of course, the extent of this rebalancing varies from text-to-text. Thus, for example, Stephanopoulos’ book, published in 1984, (Stephanopoulos, 1984) features significant sections covering design and implementation issues for process control systems. Seborg, Edgar and Mellichamp (1989) includes one section at the end of their book on Process Control Strategies. Ogunnaike and Ray (1994) book includes a final chapter on Process Control System Synthesis, in which several case studies based on unit operations (distillation, reactors of various kinds) are presented. Marlin (1995) includes extensive discussion of the benefits of process control as well as a comprehensive treatment of process control system design. Whilst it might be argued that the inclusion of this more synthetic material in modern books reflects recent developments in process control research, it is clear that the early practitioners in their writings placed more emphasis on these aspects of process control than did the developers of early course materials. Moreover, published material was available quite early (particularly Buckley, 1964) which might have been used to form a basis for a balanced, systems-oriented treatment of process control topics at undergraduate level. It is not easy to establish the impact of the chosen emphasis of early process control teaching on the development of research and practice in the area, but anyone involved in university education would find it difficult to accept that there have been no consequences of importance.
2.2. Process design The state of the art in process design teaching in the early 1960s is summarised by Sherwood in the Preface to his book A Course in Process Design (Sherwood, 1963): ‘‘It has been common to include a senior ‘Plant Design’ or ‘Projects’ course in chemical engineering curricula. The purpose is to provide the student with an experience in synthesis, pulling together his knowledge of science and engineering for application
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to a practical design problem. The problems are long and complicated, often requiring 10 or more h/week during an entire term, and a lengthy report. Much ‘handbook engineering’ is involved and considerable time is devoted to cost estimation.’’
Sherwood goes on to contrast the traditional approach with his proposed design course involving the following key features. 1. The use of the case method, with process engineering problems selected to clarify the meaning of engineering design. 2. An organisation of the principles and philosophy of process design as a framework on which to hang the cases. 3. The use of four to eight cases per term, so as to include a variety of technical subjects. 4. The inclusion of cases where answers cannot be obtained by analysis alone, requiring the students to turn to the laboratory for missing information. 5. The requirement that the student invent process schemes. 6. A diversity of case types, including some which can be handled by sophisticated scientific analysis, as well as some in which labour costs or fluctuating selling prices are much more important than the result of analysis. 7. Inclusion of cases based on principles which the student has not previously studied but which he can get by a limited amount of reading, or from guest lecturers brought in for the purpose. In his book, Sherwood first discusses the key elements of process design, and the role of analysis in design problem solving. There is an interesting emphasis on formal cost optimisation in this first chapter, and indeed throughout the book. Subsequent chapters present a wide variety of carefully selected design case studies which can be used either as the basis for student exercises or possibly in an expository fashion to illustrate key issues in process design. Sherwood’s book is a mine of useful insights. Its careful study would give students valuable experience and enable those with the ability to learn general lessons from particular experiences to develop process design knowledge and skills. However, what is missing is a conceptual framework and systematic methods to tackle particularly the synthetic element in the solution of process design problems. This missing element had been identified in the 1960s, and led to the initiation of research into the field of process synthesis. One of the fruits of this research has been the development of pedagogical materials suitable for use at undergraduate level. One of the pioneers in the development of teaching materials based on a systematic approach to process
design problems was Dale Rudd, who led the development of two fine textbooks addressing the need for a conceptual framework to support pedagogical activities in process design. The first of these, Strategy of Process Engineering was published in 1968. The treatment of design methods and tools in the book was comprehensive for the time. The book is divided into three parts dealing with, The Creation and Assessment of Alternatives; Optimisation, and Engineering in the Presence of Uncertainty. The first part begins with a discussion of the major issue of problem definition, converting what Rudd calls a ‘Primitive Problem’ into one or more specific problems amenable to the application of engineering knowledge and skills. Fig. 1, taken from the book, illustrates the approach which Rudd advocates here. Subsequent chapters in this Part deal with methods to evaluate alternative solutions based on economic and technical criteria. There is very little in this book on process synthesis, other than a reference to two of Rudd’s recently published papers (Rudd, 1968; Masso & Rudd, 1969) on the subject. Clearly, the publication of this book came slightly too early to capitalise on the results of research in process synthesis (but see below). The other two parts of the book describe techniques and tools to address on the one hand the development of optimal process systems and on the other the modelling and design of systems taking account of various kinds of uncertainty. Strategy of Process Engineering is the only ‘systems’ text to be recognised by Freshwater in his review of the literature of chemical engineering (Freshwater, 1989). Freshwater’s evaluation is as follows: ‘‘It was the first book to recognise (a) that design was not something picked up by experience but was a formal procedure with its own rules which could not only be learnt by students but could be taught in a rigorous manner and (b) that the chemical engineer needed to know about a whole range of techniques outside the narrow ever more scientific approach of chemical engineering science. Here is a book that truly reflects the practice of the profession in industry far more than any other published in the same time period. Hence … it is a very significant book and will be seen as such in the future.’’
Not content with this one pioneering achievement, Rudd was involved in the production of a second significant contribution 5 years later. Process Synthesis (Rudd, Powers & Siirola, 1973) appears to be the first text entirely devoted to setting out a conceptual framework and to providing methods to help students to develop flowsheets for new processes from scratch. The motivation of the authors is made clear in the book’s Preface:
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‘‘Since World War II, engineering education has moved strongly toward analysis, with courses dealing with individual process operations and phenomena. Transport Phenomena, Unit Operations, Process Control (sic!), Reaction Engineering, and other engineering science courses greatly strengthened engineering education by showing how things are and how they work. Unfortunately, there was not a parallel development of courses dealing with synthesis … This deficiency has been recognised for years, but the remedy awaited the development of sufficiently general principles of synthesis about which to organise educational material.’’
Process Synthesis has been used to good effect in undergraduate teaching of process design, but its aim to tackle the issues of synthesis using a combination of qualitative methods and rudimentary analysis to guide decision making prompted the exploration of alternative pedagogical approaches. The development of methods based on pinch analysis has led to two books suitable for undergraduate use.
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The Users’ Guide on Process Integration for the Efficient Use of Energy (Linnhoff et al., 1982) concentrates on methods for the synthesis of heat exchanger networks. Smith (1995) book combines discussion of methods based on pinch analysis (e.g. for energy integration and waste minimisation) with qualitative methods (e.g. for reaction and separation system synthesis). Douglas (1988) book presents a systematic method for conceptual process design based on the use of short-cut calculations within the framework of a depthfirst search to rapidly screen process alternatives and come up with a viable process flowsheet. The book is designed to form the basis for a one-semester, senior level course in process design, and has been used for that purpose in many departments with excellent results, as well as to train practising engineers in industry to be more effective process designers. More recently, two books have been published which provide a more comprehensive coverage of design techniques (both synthesis and analysis) rather than seeking to help students develop their skills in the application of one particular approach. Biegler, Grossmann and Westerberg (1997) have assembled in their text the contents
Fig. 1. Solving engineering problems (from Rudd & Watson, 1968).
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The contrast between the historical development of teaching in process control, as evidenced by textbooks, and that in process design, is a striking one. In both cases, an appropriate balance between synthesis and analysis is being sought. In control, an early emphasis on analysis has been redressed to a greater or lesser extent by subsequent texts, whereas the synthetic element was present in the very earliest systems-orientated design texts. The balance between synthesis and analysis in any given course is a key issue, depending on many factors. My personal view is that chemical engineering courses should include a significant component of synthesis, and that the process systems elements of the undergraduate curriculum are key in delivering that requirement.
3. Historical developments —the systems approach In parallel with developments aimed at helping students to learn methods, techniques and tools applicable to particular classes of engineering problem, a strand of process systems engineering teaching has evolved which seeks to help students to develop a ‘systems approach’ to the general practice of their profession. One of the early pioneers of this strand was Rippin (1969):
Fig. 2. A ‘systems approach’ (taken from Rippin, 1969).
of a number of undergraduate and graduate level courses developed and run at Carnegie-Mellon University since the late 1970s or 1980s. Seider, Seader and Lewin (1999) present a comprehensive treatment of synthesis and analysis techniques for the design of continuous processes. This book includes an extensive discussion of techniques for plant-wide controllability assessment, and thus represents the first attempt in an undergraduate text to unify process and control system design. One final point should be made on the pedagogical materials supporting a process systems approach to process design, there is very little on the design of batch processes. Only Biegler et al. (1997) devote significant amounts of space to this topic. Of course, there have been many pedagogical contributions to what might be called ‘enabling technologies’ in process systems engineering, notably in mathematical and computational techniques such as flowsheeting, simulation and optimisation. This author’s decision not to include a review of developments in these key areas should not be taken to imply that they are not important contributions to the development of process systems education!
‘‘David was opposed to general-purpose systems techniques, advocating rather systems thinking’’ (Sargent, personal communication 1999).
Fig. 2 is taken from Rippin (1969). It shows a procedure for tackling complex engineering problems using systems engineering methodologies and techniques. Thus, ‘Systems Engineering’, as perceived by Rippin and others, is a general set of methodologies and tools for solving engineering problems involving complex systems (see also Jenkins, 1969, Jenkins was one of David Rippin’s collaborators in the founding of a new Department of Systems Engineering at the University of Lancaster in 1966). Problem solving is a field of education which has received a lot of attention from the academic community, particularly in engineering but also elsewhere. Rather than review the large literature on this broad topic, I will focus on two activities within our own community. The most comprehensive approach to the development of problem solving skills for undergraduate chemical engineers has been that developed at McMaster University under the leadership of Donald Woods (Woods et al., 1997). On the basis of a very careful analysis of the undergraduate curriculum (involving, among other things, one of the faculty enrolling as an undergraduate and attending the entire 4-year pro-
J. Perkins / Computers and Chemical Engineering 26 (2002) 283–293 Table 1 Problem solving course components at McMaster University (from Woods et al., 1997) (a) 1 2 3 4 5 6 7 8 9 10 11
Awareness (1–4 h)‡ What is problem solving? (1 h)‡ Self-assessment (3–6 h)‡ Strategies (1.5–5 h)‡ I want to and I can, stress management (1–2 h)‡ Analysis, classification (2–4 h)‡ Creativity (6–8 h)‡ Introduction to visual thinking, translation (2 h) Define the stated problem (2 h)‡ Getting unstuck (1 h) Identifying personal preference and implications (2 h workshop plus 3 h completing forms)‡ 12 Learning skills (2 h workshop plus 1 h taking notes)‡ 13 Analysis, consistency (1–3 h) 14 Creating the look back and extending experiences (2–4 h)‡ 15 Exploring the situation to identify the real problem (2–4 h)‡ 16 Tactics (2–3 h) 17 Time management for individuals (2–4 h)‡ 18 Evaluation and stress management (1–2 h) 19 More on visual thinking, reading P&IDs (2–5 h)† 20 Asking questions (4–8 h)† 21 Analysis, sequences and series (2–4 h) 22 Broadening perspectives (1–4 h) 23 Obtaining criteria (2 h) 24 Decision making (2–4 h) 23–24a Criteria and decision making in the context of career counselling and guidance 25 Time management for groups and projects (2 h) 26 Listening and responding (a) Attending and following (1 h) (b) Body language (1 h) (c) Reflecting (1 h) 27 Group skills and 28. Group evaluation (90 min–4 h)† (b) 29 30 31 32 33 34 35 36 37 38 38a 39 39a 40
Being an effective chairperson (15 h)* Analysis, reasoning and drawing conclusions (5–7 h) Defining real problems (1.5–4 h) Implementing (2–4 h) Coping with ambiguity (10–15 h)* Trouble shooting (8–10 h)* Heuristics or rules-of thumb for problem solving (3–5 h) Self-directed learning or problem-based learning (1.5–3 h)†* Simplifying and generalising (2–4 h) Consolidating the knowledge structure Consolidating the knowledge structure in chemical engineering (6–8 h) Creating tacit information or experience knowledge Creating tacit information or experience knowledge in chemical engineering (2–4 h) Successive approximation and optimum sloppiness (2–4 h)*
Other units 41 Finding opportunities (1–2 h) 42 Procrastination and other attitudes (2–4 h) 43 Giving and receiving feedback (1–3 h) 44 Assertiveness (2–4 h) 45 Coping creatively with conflict (90 min–3 h)
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Table 1 (Continued) 46 47 48 49 50 51 52 53 54 55 56 57
Coping with difficult behaviours (2–5 h) Accentuating the negative (1–3 h) Communication (30 h) Coping with change (1–5 h)† Being a change agent (3 h) Managing change (3 h) Fundamentals of interpersonal skills (1–5 h)† Effective teams and team building (1–8 h) Goals, mission and vision (4–6 h) Roles and responsibilities in teams (2–3 h) Networking, how to enrich your life and get things done (1–24 h) Convincing others, getting a buy-in (3–5 h)
Core units for course chemical engineering 2G2, development of individual skill in solving reasonably well-defined problems (48 h available with selection from the following units depending on the needs of the students. The usual selections are indicated with a ‡. Chemical engineering 3E4, development of individual skill in solving vaguely-defined, chemical engineering problems (18 h available for the synthesis and application of skills developed in Chemical Engineering 2G2). Core units for course Chemical Engineering 3G3, development of interpersonal skills, lifelong learning and team problem solving skills for open-ended, systems and people problems (24 h available with selection from the following units depending on the needs of the students. The usual selections are indicated with a †. Core units for course chemical engineering 4N4, development of interpersonal skills, lifelong learning and team problem solving skills for ill-defined and open-ended technical and interpersonal problems (30–50 h available with selection from the following units depending on the needs of the students. The * indicates the usual topics with the total hour dependent on the degree to which the activities combine knowledge with MPS skill acquisition. For example, for MPS unit 29, 1 h is devoted to understanding the target skill and the feedback forms; the 14 h is spent in meetings that each person chairs. The meeting can be used to learn the subject knowledge.
gramme!), an extensive set of courses has been developed (see Table 1a and b). One hundred twenty contact hours are available in the undergraduate course in chemical engineering at McMaster to deliver a selection of this material (Woods states that 200 contact h would be required to deliver the entire set of courses). The goals of the McMaster programme are very comprehensive, and clearly go beyond the scope of even a broad definition of process systems engineering education. Nevertheless, significant parts of the course are highly relevant to the development of a systems approach, particularly some of those in the third and fourth year courses (courses 3G3, 4N4). The programme takes a ‘bottom-up’ approach to the development of problem solving skills. The early courses are concerned with individual students working on comparatively well-defined problems. More open-ended problems are tackled in later years, where the nature of the problems often implies a team-based approach. Higgins, Maitland, Perkins, Richardson and Warren Piper (1989), in describing a course on engineering problem solving offered to first-year undergraduates in chemical engineering at Imperial College, identify three
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generic types of problem which engineers are called upon to solve, problems of prediction (e.g. what is the time T taken for a train moving at a steady speed S to travel between stations A and B which are at a distance D apart?); problems of explanation (why are all numbers of the form abcabc (e.g. 791791) divisible by 7, 11 and 13?); problems of invention (devise a method for ensuring that flying aircraft always keep a safe distance from each other). The course focuses on the third type. In a 2-week workshop involving roughly 25 contact h, students are helped to develop and apply a systematic approach to tackling problems of invention. The stated objectives of the course are that, students adopt a convention for stating problems which leads to a systematic way of writing design briefs; students’ creativeness is tapped and manifests itself in a confidence in producing a diversity of solutions to a problem and in avoiding common pitfalls in problem-solving; students can evaluate potential solutions against their brief; solutions are presented in an effective way; students become more effective members of design teams. A simple model of problem-solving is presented, consisting of six stages— defining the problem; conceiving possible solutions; evaluating solutions and choosing one of them; producing the chosen solution; presenting the chosen solution; and evaluating the pro-cess of problem-solving. (There are resonances here with the text of Rudd and Watson discussed in the previous section. Incidentally, it is also interesting to note that Donald Woods was one of the people mentioned by those authors as using their text ‘in its 6arious stages of de6elopment in the uni6ersity classroom’ (Rudd & Watson, 1968)). Students are introduced to the components of the framework and then apply it to realistic engineering problems (e.g. developing proposals for the reduction in the energy
usage of a given plant) during the course of the workshop. 4. The current position In this section, information on the present content of the undergraduate course at Imperial College will be presented, as an illustration of current practice (at least in one department with which the author is familiar) in process systems teaching. The undergraduate programme at Imperial College extends over 4 years, leading to the degree of Master of Engineering (M. Eng.). A high-quality intake of around 80 students enters the first year each year, to be taught by a faculty consisting of just over 30 people (of whom eight are involved in process systems teaching and research). In the first 3 years of the course, the students’ working day is divided into two, with lectures and tutorials confined to one half of the day (typically the mornings). Project work occupies the other half-day. There are no class activities on Wednesday afternoons, to allow students to participate in sports. Thus, in a ‘4-week project’, students are expected to undertake roughly 50 h of work (In practice, they often spend far more time than this!) The first term of the final (fourth) year shows a similar pattern, but in the second term of 11 weeks the students spend most of their time on the final design project. Information on the current core and elective systems courses is shown in Table 2. In assessing the proportion of the total course devoted to systems-related activities, it is worthwhile to note that the first 3 years of the course include 220–235 lectures. The final year contains about 120. Project work runs for between 15 and 20 of the weeks in the first 3 years. On that basis, lecture courses in systems topics contribute roughly 10% of the overall lecture programme, and systems-related projects roughly 40% of the total project load. A student interested enough to take up all elective slots with systems topics would pursue a programme with about 20% systems lectures and approaching 50% systems projects, the elective courses having project work associated with them.
Table 2 Systems components of the current undergraduate programme at Imperial College, London Year of study
Lectures
Projects
First year
Process analysis, 24, lectures text, Felder and Rousseau (1986)
Second year
Process dynamics and control, 30 lectures text, Stephanopoulos (1984)
Third year
Strategy of design, 20 lectures text, Douglas (1988). Elective, Dynamic Behaviour of Process Systems, 40 lectures plus 20 h project work Electives, Advanced Process Synthesis; Advanced Process Control; Stochastic and Adaptive Systems; Flexible Process Operations, all 40 lectures plus 20 h project work
Design, 2 weeks; pilot plant, 3 weeks Process control, 4 weeks; pilot plant, 3 weeks Synthesis/flowsheeting, 4 weeks
Fourth year
Design, 11 weeks (full-time)
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Table 3 Educational objectives of core lecture courses at Imperial College Course and year
Process Analysis, year 1
Process Dynamics and Control, year 2
Strategy of Process Design, year 3
Objectives By the end of the course, students should be able to Quantitatively describe the behaviour of steady-state flow systems in terms of pressures, temperatures, flow rates and compositions Perform steady-state mass balances on an entire process in order to calculate flow rates and compositions within that process system which may include chemical reaction(s), simple separation(s), purge stream(s), recycle(s), and similar complications Perform steady-state energy balances as above, given certain thermodynamic simplifications Assess the economic potential and possible environmental impact of processes, given suitable data Organise themselves into groups which, when faced with a complex problem, can plan a strategy for its efficient solution Derive mathematical models describing the transient behaviour of simple lumped systems in the time domain Derive linearised models from the above mathematical models and use them to deduce the important qualitative features of the transient process behaviour Describe the need for, and the fundamental objectives of, process control for specific applications Describe the relative benefits and limitations of feedback and feedforward control schemes Select and tune simple and cascaded feedback controllers suitable for a variety of common applications Devise and tune simple feedforward control schemes used either in isolation or in conjunction with feedback control Select appropriate control structures for unit operations involving several potential measurements and control manipulations Develop process designs using the Douglas methodology Use computer-based flowsheeting tools as calculational aids in process design problems Apply pinch analysis techniques to the solution of heat exchanger network problems
More details on the core lecture courses are given in Table 3 in the form of the declared educational objectives of each course. Details of the objectives of the design project in first year have been discussed in the previous section. The second and third year design projects are based on open-ended exercises designed to enable students (working in groups) to develop through practice and display the skills involved in the more synthetic elements of the corresponding lecture courses. In second year, the students work on a simulated industrial furnace devising and implementing a process control system. The third year project is based on applying the Douglas method to an example. Students in groups of four go through all stages of the method; flowsheeting tools are available for use at the students’ discretion. The aim of these projects is to prepare students to tackle the final design project in fourth year. There, the students work in larger groups to produce a comprehensive process design involving process synthesis, design of key units, safety and layout, environmental impact, operation and control, and economics. In addition to the design projects in each year of the 4-year programme, students gain practical experience of process control and operation through two pilot-plant projects, one in each of first and second years. The details of these projects have been described elsewhere (Macchietto & Kershenbaum, 1987). A development in the last decade in the UK has been the introduction of 1-year taught Masters programmes,
typically leading to an M.Sc. degree and involving formal lecture-based material combined with a substantial dissertation. An M.Sc. in Process Systems Engineering was introduced at Imperial College in 1996. Five modules, each consisting of 40 lectures and 20 h of project work, constitute the formal part of the course. The current modules are, Dynamic Behaviour of Process Systems; Advanced Process Synthesis; Advanced Process Control; Stochastic and Adaptive Systems; and Flexible Process Operations. These modules also form the elective systems courses offered to undergraduates.
5. The future The development of the curriculum in chemical engineering has benefited in the past from the tension between, on the one hand, imparting to the students a good understanding of the sciences underpinning our discipline and, on the other, the perceived need to help aspiring engineers to develop and enhance the skills necessary to practice as an effective professional. It is my view that a balance between educational activities designed to achieve each of these goals will continue to be an important feature of our discipline if it is to retain its uniqueness. We have seen that addressing the educational objectives associated with the more synthetic aspects of engineering practice was a goal of educators in process
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systems engineering from the earliest days. It is my hope that our community will continue to wrestle with the challenges of helping students to become more effective engineering problem solvers by developing even better courses on the techniques of process systems engineering and their application. In doing so, we should recognise that the opportunities for chemical engineers to apply their knowledge and skills have broadened from the traditional arena of petrochemicals to a whole range of industries where chemical and biochemical transformations are the means to wealth creation. The implication for courses in process systems engineering is that they should seek to be broad in application, emphasising the general rather than the specific wherever possible. The development of courses for chemical engineers in the area of product design (Moggridge & Cussler, 1999; Westerberg & Subrahmanian, 2000) represents one exciting opportunity to broaden the concerns of process systems engineering education in response to these trends. Another area where more pedagogical material could usefully be produced is that of process modelling. The development of appropriate mathematical models of process systems is a synthetic activity. Indeed, many characterise it as an art, in the same way as process design has been characterised in the past. There are current efforts (e.g. at the University of Queensland in Australia (Cameron, 2000)) to develop courses specifically designed to help students to attack the problem of developing an appropriate mathematical model of a process system in a systematic way. The eventual publication of educational materials based on these prototype courses and the widespread introduction of such courses into the core undergraduate curriculum would be a very useful step in terms of developing graduate chemical engineers who will ‘fit for purpose’ in the new millennium. As well as educating our students in systems techniques and tools, we are excellently placed to address the more general educational objectives associated with what I have called in this paper the ‘systems approach’. Indeed, many of you will feel that it is unhelpful to make this division; our goal should be to educate effective professionals who are able to take a systematic approach involving systems thinking, techniques and tools. If reading this paper has encouraged you in that view, then my main objective has been achieved!
6. Conclusions In this paper, I have presented a personal view of the development of process systems engineering education. The development of process design and control teaching has been presented through an analysis of some of the key textbooks that have been published in the past
40 or more years. We have seen that a synthetic element was present even in the earliest systems-orientated process design texts, whereas the most popular early process control texts took a strongly analytical approach. Fortunately, this situation has been recovered to some extent in the past 15 years, and more modern control texts include synthetic material to a greater or lesser extent, offering an instructor discretion in the balance of the course he or she chooses to deliver. Using quotations from some of these texts, I have tried to show that these authors, and others in our community, were concerned with more than the education of students in the use of systems techniques and tools. They also embraced the synthetic nature of chemical engineering, and sought to help students acquire the skills needed to tackle open-ended engineering problems. Indeed, it is probable that these concerns provided one of the motivations for early research in process systems engineering. I have relied on a description of the course at Imperial College to characterise the current situation. It is unlikely that there is such a thing as a ‘typical’ chemical engineering course these days. The discipline shows a healthy diversity in curriculum adopted in different departments, which in my view should be further encouraged. Nevertheless, it is hoped that a description of how one department currently approaches this area in its undergraduate course will be of interest. For the future, in my view it will be important for us to retain and indeed to strengthen the commitment of the pioneers of process systems education to helping our students to develop a ‘systems approach’. Not only should we continue to enhance our students’ education in systems tools and techniques (such as modelling where more systematic courses are on the way). We could also usefully strengthen our courses by contributing to the development of ‘systems thinking’ or the ‘systems approach’ in our students. It is the combination of a strong and broad base in engineering science and the ability to synthesise as well as analyse complex systems that is the unique feature of chemical engineering. The process systems engineering community is the natural keeper of the synthetic component of chemical engineering education. I hope that we will continue to recognise and embrace this responsibility as we develop courses suitable for the chemical engineers of the future.
References Biegler, L. T., Grossmann, I. E., & Westerberg, A. W. (1997). Systematic methods of chemical process design. Englewood Cliffs, NJ: Prentice-Hall. Buckley, P. S. (1964). Techniques of process control. New York: Wiley.
J. Perkins / Computers and Chemical Engineering 26 (2002) 283–293 Cameron, I. T. (2000). See http://daisy.cheque.uq.edu.au/cape/ modelling/index.htm. Ceaglske, N. H. (1956). Automatic process control for chemical engineers. New York: Wiley. Coughanowr, D. R., & Koppel, L. B. (1965). Process systems analysis and control. New York: McGraw-Hill. Douglas, J. M. (1988). Conceptual design of chemical processes. New York: McGraw-Hill. Felder, R. M., & Rousseau, R. W. (1986). Elementary principles of chemical processes. New York: Wiley. Freshwater, D. C. (1989). The development of chemical engineering as shown by its texts. In N. A. Peppas, One hundred years of chemical engineering (pp. 15 –25). Dordrecht: Kluwer Academic Publishers. Higgins, J. S., Maitland, G. C., Perkins, J. D., Richardson, S. M., & Warren Piper, D. (1989). Identifying and solving problems in engineering design. Studies in Higher Education, 14, 169 –181. Huckaba, C. E., & Monet G. P. (1963). Process systems engineering. CEP Symposium Series 59. Jenkins, G. M. (1969). The systems approach. Journal of System Engineering, 1, 3 – 49. Linnhoff, B., Townsend, D. W., Boland, D., Hewitt, G. F., Thomas, B. E. A., Guy, A. R., & Masland, R. H. (1982). User guide on process integration for the efficient use of energy. Institution of Chemical Engineers. Luyben, W. L. (1974). Process modeling, simulation and control for chemical engineers. New York: McGraw-Hill. Macchietto, S., & Kershenbaum, L.S. (1987). The IBM Project for Chemical Engineering at Imperial College. IChemE Symposium Series Number 101, (307–321). Marlin, T. E. (1995). Process control — designing processes and control systems for dynamic performance. New York: McGraw-Hill. Masso, A. H., & Rudd, D. F. (1969). The synthesis of process designs, II. Heuristic structuring. American Institute of Chemical Engineering Journal, 15, 10 –17. Moggridge, G., Cussler, E. (1999). An introduction to chemical product design. Presented at a meeting on ‘Product Engineering’, Uni6ersity of Birmingham, April 1999 (see, http:// www.cheng.cam.ac.uk/news/abstract15april99.html). Ogunnaike, B. A., & Ray, W. H. (1994). Process dynamics, modelling and control. Oxford: Oxford University Press.
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Rippin, D. W. T. (1969). Applications of systems engineering in the chemical and process industries. The Chemical Engineer (London) 174, CE284 – CE288, 305. Rudd, D. F. (1968). The synthesis of process designs, I. Elementary decomposition principle. American Institute of Chemical Engineer Journal, 14, 343 – 349. Rudd, D. F., & Watson, C. C. (1968). Strategy of process engineering. New York: Wiley. Rudd, D. F., Powers, G. J., & Siirola, J. J. (1973). Process synthesis. Englewood Cliffs, NJ: Prentice-Hall. Sargent, R. W. H. (1963). Chemical engineering and engineering science. Inaugural lecture as Professor of Chemical Engineering, Imperial College, 12 March 1963. The Chemical Engineer (London), 168, CE151 – CE155. Seborg, D. E. (1980). A survey of process control education in the United States and Canada. Chemical Engineering Education, 14, 42 – 44. Seborg, D. E., Edgar, T. F., & Mellichamp, D. (1989). Process dynamics and control. New York: Wiley. Seider, W. D., Seader, J. D., & Lewin, D. R. (1999). Process design principles: synthesis, analysis and e6aluation. New York: Wiley. Shemilt, L. W. (1980). A century of chemical engineering education in Canada. In: W. F. Furter, History of Chemical Engineering, Advances in Chemistry Series no. 190, (pp. 167 – 204), ACS Publications. Sherwood, T. K. (1963). A course in process design. Cambridge, MA: MIT Press. Smith, R. (1995). Chemical process design. New York: McGraw-Hill. Stephanopoulos, G. (1984). Chemical process control: an introduction to theory and practice. Englewood Cliffs, NJ: Prentice-Hall. Westerberg, A. W., & Subrahmanian, E. (2000). Product design. Computers and Chemical Engineering, 24, 959 – 966. Williams, T. J. (1961). Systems engineering for the process industries. New York: McGraw-Hill. Woods, D. R., Hrymak, A. N., Marshall, R. R., Wood, P. E., Crowe, C. M., Hoffman, T. F., Wright, J. D., Taylor, P. A., Woodhouse, K. A., & Bouchard, C. G. K. (1997). Developing problem solving skills: the McMaster problem solving program. Journal of Engineering Education, 86 (Part 2), 75 – 91. Young, A. J. (1955). An introduction to process control system design. New York: Longman.
Education in process systems engineering: past, present and future John Perkins * Department of Chemical Engineering and Chemical Technology, Center for Process Systems Engineering, Imperial College of Science, Technology and Medicine, London SW 7 2BY, UK Received 16 August 2000; received in revised form 27 November 2000; accepted 27 November 2000
Abstract The term ‘Process Systems Engineering’ may be traced back at least as far as the early 1960s. In parallel with the emergence of a research agenda for this new sub-discipline, pioneers of the subject began to consider the nature of education in process systems engineering, and its relationship to the broader chemical engineering curriculum. In this paper, a personal view of the history of the development of education in our field will be given. It will be argued that two complementary approaches have been pursued, each of which has played an important role both within the sub-discipline itself and in the context of the development of chemical engineering education more broadly. On the one hand, pedagogical materials have been developed and courses delivered covering important advances in process systems engineering as they have emerged from the research community. As a result, the teaching of design and control methodologies, techniques and tools has become more systematic and comprehensive in the past four decades, reflecting the strides made by the research community in tackling these complex engineering problems. In parallel with these developments, educators have been concerned to develop curricula and courses designed to help students to adopt a ‘systems approach’ to engineering problem solving. Here, the objective has been not so much to help students to learn about the application of specific ideas and methods to particular classes of engineering problem. Rather the aim has been to encourage students to adopt a particular, systematic approach to their entire professional practice. Advances in both directions will be illustrated through examples taken from the literature, as well as through an account of the process systems engineering components of the chemical engineering course at Imperial College. Finally, the author will present his personal view on developments which are likely to emerge in the future, as process systems engineering and chemical engineering continue to respond to external changes as well as to the continuing development of our subject. © 2002 Published by Elsevier Science Ltd. Keywords: Process systems engineering; Education; Chemical engineering
1. Introduction The Process Systems Engineering conference series was inaugurated in 1982, at the initiative of Professor Takeichiro Takamatsu, then of Kyoto University. However, the term ‘systems engineering’ has a much longer history, and by the early 1960s a number of chemical engineers had recognised the opportunities to develop systems concepts appropriate to the practice of their profession. As early as 1959, T.J. Williams, at that time an employee of the Monsanto company, used the opportunity provided by an invitation from the Univer* Tel.: +44-207-589-5111. E-mail address: [email protected] (J. Perkins).
sity of Texas to deliver the Schoch lectures for that year to present his impressively broad vision of Systems Engineering for the Process Industries (Williams, 1961). Huckaba and Monet (1963) in the Foreword to a CEP Symposium Series volume, entitled Process Systems Engineering and published in 1963, stated that: ‘‘Chemical engineers are primarily interested in process systems engineering in which the systems approach is employed in the design and operation of chemical processing plants.’’
In the same year, we find in the text of the Inaugural Lecture of Roger Sargent as Professor of Chemical Engineering at Imperial College (Sargent, 1963):
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‘‘…broad consideration of the interaction between the performance of individual units and the requirements of the process has always been a feature of good process design, but in recent years it has become fashionable to refer to this as ‘optimisation’, and it has even come to be regarded as a new, separate branch of engineering, known as ‘systems engineering’. However, new names rarely appear without good cause and in this field the advent of automatic computers has given rise to a whole range of techniques which have revolutionised the approach here …’’
It is not the purpose of this paper to trace the history of the development of process systems engineering. Our goal will be to seek to map changes in the education of students of chemical engineering, which have resulted from the emergence of process systems engineering concepts in the past four decades or so. It will be argued that there are two strands to these developments. On the one hand, pedagogical materials have been developed and courses delivered covering important advances in process systems engineering as they have emerged from the research community. In tracing these developments, a method used by Freshwater (1989) to trace the development of the conceptual basis of chemical engineering itself will be employed, viz. the analysis of key textbooks. Inevitably, in a paper of this length, it will not be possible to give a comprehensive review. Nor will such a review be necessary for our purposes. Rather, we shall focus on what seem to be some of the pioneering contributions (restricted to those published in English) in order to investigate the emergence of the major themes in process systems engineering education. The second strand of educational development concerns curricula and courses designed to help students to acquire and adopt a ‘systems approach’ to engineering problem solving. While there are much broader questions involved in pursuing the educational objectives associated with this strand, and the issues extend well beyond the boundaries of process systems engineering, nevertheless process systems engineers have made pioneering developments here also. Indeed, there is some evidence that the desire to help students to develop the skills needed to tackle complex engineering problems partly motivated the early research in process systems engineering.
2. Historical developments-techniques and tools Process Systems Engineering is concerned with the development of techniques and tools to address the generic manufacturing problems of design, operation
and control for the process industries. In tracing the pedagogical developments in the field, it will be convenient to consider control and design separately, since these topics have tended to appear in curricula as separate courses.
2.1. Process control Compulsory courses in process control can be found in the undergraduate curriculum of some departments as early as 1950 (e.g. Shemilt, 1980) and textbooks on the subject were published in that decade. One of the early textbooks to appear, first published in 1955, was A.J. Young’s An Introduction to Process Control System Design (Young, 1955). Young was an employee of ICI, who in 1946 had been given the responsibility of setting up what became the Central Instrument Laboratory of that company. The book reflects the long-standing concerns of industrial process control engineers keen to promote the benefits of their technology. To quote from the Preface to the book: ‘‘The first necessity at the present time is to ensure that the most economic use is made of existing knowledge and equipment. The second is to show plant designers that the full benefits of automatic control cannot be enjoyed without their co-operation, and to obtain their co-operation’’ (Young, 1955).
Chapter 1 of the book is entitled ‘Economics’ and discusses in some detail the benefits that may be expected through the application of appropriate automatic control technology in the process industries. A treatment of the characteristics of control loops and of plant dynamics is followed by a chapter on ‘Plant Controllability’ (chapter 5), which is defined by Young as ‘the ease or difficulty of controlling a plant’. In subsequent chapters, it is shown how frequency response methods may be used to quantify controllability, as well as to set up appropriate process control systems. In the year following the publication of Young’s book, Norman Ceaglske, a Professor of chemical engineering at the University of Minnesota, published Automatic Process Control for Chemical Engineers, a textbook based on an elementary course taught to undergraduates at that university (Ceaglske, 1956). After a short introductory section describing in qualitative terms the components of process control systems, the remainder of the book is concerned with mathematical techniques for the analysis of simple control systems. While being somewhat narrow in its focus, this book appears to represent the first academic text in process control specifically designed for chemical engineering undergraduates.
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Another pioneering book produced within in an industrial context is Page Buckley’s Techniques of Process Control, published in 1964 (Buckley, 1964). Buckley had extensive industrial experience as a process control engineer with Du Pont. In the Preface to his book, Buckley is at great pains to emphasise the synthetic nature of process control: ‘‘…we are not so much interested in knowing precisely how a system behaves as we are in knowing how to design it so that it will operate satisfactorily. In other words, we are primarily interested in synthesis rather than analysis, in logic rather than computation.’’
After a review of developments in control up to 1964, the book deals first with the Mathematics of Process Control (Laplace and z-transformations, frequency response, block diagram algebra, and linearisation methods). The following section on Process Control Theory includes an important chapter on Overall Process Control as well as discussion of more traditional topics such as Stability, Sampled Data and Distributed Systems. Three more sections deal with the dynamics and control of the important process operations of fluid flow, heat transfer and distillation. Throughout the book, theory is used to help decide the important structural questions associated with the synthesis of process control systems. Although both of the ‘industrial’ books discussed above represent pioneering efforts to codify the subject, their presentation probably made their adoption as the basis of first courses in process control somewhat impractical. Indeed it is clear that the authors themselves considered practitioners rather than undergraduate students as their prime audience. By the 1960s, a clear need had emerged to provide undergraduate texts in the subject to serve the growing number of departments around the world keen to incorporate process control into their core curriculum. Nineteen sixty-five saw the publication of a book that was to dominate the field for what was, in retrospect, a surprising length of time, Process Systems Analysis and Control by Coughanowr and Koppel (1965). The book was developed from the required senior course, which had been given at Purdue University since 1960. In contrast to the books of Young and of Buckley, the focus of Coughanowr and Koppel is on the analysis of process and control system dynamics. Of the book’s 32 chapters, only one (chapter 23) deals with process applications, illustrating the issues faced in the implementation of complex process control systems through a discussion of distillation column control. A survey of process control education in North America in 1978 (Seborg, 1980) showed that of the 135 schools which responded to the survey, 69 were using
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Coughanowr and Koppel’s book for their undergraduate control teaching, and a further seven for graduate level teaching. Luyben’s book (1974), published 4 years before the survey was conducted, had the second largest number of entries with 21. Again, the emphasis of the book was on analysis with a very short section of six pages devoted to control-systems design concepts). In hindsight, this dichotomy between the analytical treatment of the subject in the most popular university texts, and the published writings of industrial process control practitioners placing great emphasis on synthetic issues is quite striking. In the last two decades, textbooks providing a balance between analysis and synthesis of process control systems have appeared. Of course, the extent of this rebalancing varies from text-to-text. Thus, for example, Stephanopoulos’ book, published in 1984, (Stephanopoulos, 1984) features significant sections covering design and implementation issues for process control systems. Seborg, Edgar and Mellichamp (1989) includes one section at the end of their book on Process Control Strategies. Ogunnaike and Ray (1994) book includes a final chapter on Process Control System Synthesis, in which several case studies based on unit operations (distillation, reactors of various kinds) are presented. Marlin (1995) includes extensive discussion of the benefits of process control as well as a comprehensive treatment of process control system design. Whilst it might be argued that the inclusion of this more synthetic material in modern books reflects recent developments in process control research, it is clear that the early practitioners in their writings placed more emphasis on these aspects of process control than did the developers of early course materials. Moreover, published material was available quite early (particularly Buckley, 1964) which might have been used to form a basis for a balanced, systems-oriented treatment of process control topics at undergraduate level. It is not easy to establish the impact of the chosen emphasis of early process control teaching on the development of research and practice in the area, but anyone involved in university education would find it difficult to accept that there have been no consequences of importance.
2.2. Process design The state of the art in process design teaching in the early 1960s is summarised by Sherwood in the Preface to his book A Course in Process Design (Sherwood, 1963): ‘‘It has been common to include a senior ‘Plant Design’ or ‘Projects’ course in chemical engineering curricula. The purpose is to provide the student with an experience in synthesis, pulling together his knowledge of science and engineering for application
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to a practical design problem. The problems are long and complicated, often requiring 10 or more h/week during an entire term, and a lengthy report. Much ‘handbook engineering’ is involved and considerable time is devoted to cost estimation.’’
Sherwood goes on to contrast the traditional approach with his proposed design course involving the following key features. 1. The use of the case method, with process engineering problems selected to clarify the meaning of engineering design. 2. An organisation of the principles and philosophy of process design as a framework on which to hang the cases. 3. The use of four to eight cases per term, so as to include a variety of technical subjects. 4. The inclusion of cases where answers cannot be obtained by analysis alone, requiring the students to turn to the laboratory for missing information. 5. The requirement that the student invent process schemes. 6. A diversity of case types, including some which can be handled by sophisticated scientific analysis, as well as some in which labour costs or fluctuating selling prices are much more important than the result of analysis. 7. Inclusion of cases based on principles which the student has not previously studied but which he can get by a limited amount of reading, or from guest lecturers brought in for the purpose. In his book, Sherwood first discusses the key elements of process design, and the role of analysis in design problem solving. There is an interesting emphasis on formal cost optimisation in this first chapter, and indeed throughout the book. Subsequent chapters present a wide variety of carefully selected design case studies which can be used either as the basis for student exercises or possibly in an expository fashion to illustrate key issues in process design. Sherwood’s book is a mine of useful insights. Its careful study would give students valuable experience and enable those with the ability to learn general lessons from particular experiences to develop process design knowledge and skills. However, what is missing is a conceptual framework and systematic methods to tackle particularly the synthetic element in the solution of process design problems. This missing element had been identified in the 1960s, and led to the initiation of research into the field of process synthesis. One of the fruits of this research has been the development of pedagogical materials suitable for use at undergraduate level. One of the pioneers in the development of teaching materials based on a systematic approach to process
design problems was Dale Rudd, who led the development of two fine textbooks addressing the need for a conceptual framework to support pedagogical activities in process design. The first of these, Strategy of Process Engineering was published in 1968. The treatment of design methods and tools in the book was comprehensive for the time. The book is divided into three parts dealing with, The Creation and Assessment of Alternatives; Optimisation, and Engineering in the Presence of Uncertainty. The first part begins with a discussion of the major issue of problem definition, converting what Rudd calls a ‘Primitive Problem’ into one or more specific problems amenable to the application of engineering knowledge and skills. Fig. 1, taken from the book, illustrates the approach which Rudd advocates here. Subsequent chapters in this Part deal with methods to evaluate alternative solutions based on economic and technical criteria. There is very little in this book on process synthesis, other than a reference to two of Rudd’s recently published papers (Rudd, 1968; Masso & Rudd, 1969) on the subject. Clearly, the publication of this book came slightly too early to capitalise on the results of research in process synthesis (but see below). The other two parts of the book describe techniques and tools to address on the one hand the development of optimal process systems and on the other the modelling and design of systems taking account of various kinds of uncertainty. Strategy of Process Engineering is the only ‘systems’ text to be recognised by Freshwater in his review of the literature of chemical engineering (Freshwater, 1989). Freshwater’s evaluation is as follows: ‘‘It was the first book to recognise (a) that design was not something picked up by experience but was a formal procedure with its own rules which could not only be learnt by students but could be taught in a rigorous manner and (b) that the chemical engineer needed to know about a whole range of techniques outside the narrow ever more scientific approach of chemical engineering science. Here is a book that truly reflects the practice of the profession in industry far more than any other published in the same time period. Hence … it is a very significant book and will be seen as such in the future.’’
Not content with this one pioneering achievement, Rudd was involved in the production of a second significant contribution 5 years later. Process Synthesis (Rudd, Powers & Siirola, 1973) appears to be the first text entirely devoted to setting out a conceptual framework and to providing methods to help students to develop flowsheets for new processes from scratch. The motivation of the authors is made clear in the book’s Preface:
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‘‘Since World War II, engineering education has moved strongly toward analysis, with courses dealing with individual process operations and phenomena. Transport Phenomena, Unit Operations, Process Control (sic!), Reaction Engineering, and other engineering science courses greatly strengthened engineering education by showing how things are and how they work. Unfortunately, there was not a parallel development of courses dealing with synthesis … This deficiency has been recognised for years, but the remedy awaited the development of sufficiently general principles of synthesis about which to organise educational material.’’
Process Synthesis has been used to good effect in undergraduate teaching of process design, but its aim to tackle the issues of synthesis using a combination of qualitative methods and rudimentary analysis to guide decision making prompted the exploration of alternative pedagogical approaches. The development of methods based on pinch analysis has led to two books suitable for undergraduate use.
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The Users’ Guide on Process Integration for the Efficient Use of Energy (Linnhoff et al., 1982) concentrates on methods for the synthesis of heat exchanger networks. Smith (1995) book combines discussion of methods based on pinch analysis (e.g. for energy integration and waste minimisation) with qualitative methods (e.g. for reaction and separation system synthesis). Douglas (1988) book presents a systematic method for conceptual process design based on the use of short-cut calculations within the framework of a depthfirst search to rapidly screen process alternatives and come up with a viable process flowsheet. The book is designed to form the basis for a one-semester, senior level course in process design, and has been used for that purpose in many departments with excellent results, as well as to train practising engineers in industry to be more effective process designers. More recently, two books have been published which provide a more comprehensive coverage of design techniques (both synthesis and analysis) rather than seeking to help students develop their skills in the application of one particular approach. Biegler, Grossmann and Westerberg (1997) have assembled in their text the contents
Fig. 1. Solving engineering problems (from Rudd & Watson, 1968).
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The contrast between the historical development of teaching in process control, as evidenced by textbooks, and that in process design, is a striking one. In both cases, an appropriate balance between synthesis and analysis is being sought. In control, an early emphasis on analysis has been redressed to a greater or lesser extent by subsequent texts, whereas the synthetic element was present in the very earliest systems-orientated design texts. The balance between synthesis and analysis in any given course is a key issue, depending on many factors. My personal view is that chemical engineering courses should include a significant component of synthesis, and that the process systems elements of the undergraduate curriculum are key in delivering that requirement.
3. Historical developments —the systems approach In parallel with developments aimed at helping students to learn methods, techniques and tools applicable to particular classes of engineering problem, a strand of process systems engineering teaching has evolved which seeks to help students to develop a ‘systems approach’ to the general practice of their profession. One of the early pioneers of this strand was Rippin (1969):
Fig. 2. A ‘systems approach’ (taken from Rippin, 1969).
of a number of undergraduate and graduate level courses developed and run at Carnegie-Mellon University since the late 1970s or 1980s. Seider, Seader and Lewin (1999) present a comprehensive treatment of synthesis and analysis techniques for the design of continuous processes. This book includes an extensive discussion of techniques for plant-wide controllability assessment, and thus represents the first attempt in an undergraduate text to unify process and control system design. One final point should be made on the pedagogical materials supporting a process systems approach to process design, there is very little on the design of batch processes. Only Biegler et al. (1997) devote significant amounts of space to this topic. Of course, there have been many pedagogical contributions to what might be called ‘enabling technologies’ in process systems engineering, notably in mathematical and computational techniques such as flowsheeting, simulation and optimisation. This author’s decision not to include a review of developments in these key areas should not be taken to imply that they are not important contributions to the development of process systems education!
‘‘David was opposed to general-purpose systems techniques, advocating rather systems thinking’’ (Sargent, personal communication 1999).
Fig. 2 is taken from Rippin (1969). It shows a procedure for tackling complex engineering problems using systems engineering methodologies and techniques. Thus, ‘Systems Engineering’, as perceived by Rippin and others, is a general set of methodologies and tools for solving engineering problems involving complex systems (see also Jenkins, 1969, Jenkins was one of David Rippin’s collaborators in the founding of a new Department of Systems Engineering at the University of Lancaster in 1966). Problem solving is a field of education which has received a lot of attention from the academic community, particularly in engineering but also elsewhere. Rather than review the large literature on this broad topic, I will focus on two activities within our own community. The most comprehensive approach to the development of problem solving skills for undergraduate chemical engineers has been that developed at McMaster University under the leadership of Donald Woods (Woods et al., 1997). On the basis of a very careful analysis of the undergraduate curriculum (involving, among other things, one of the faculty enrolling as an undergraduate and attending the entire 4-year pro-
J. Perkins / Computers and Chemical Engineering 26 (2002) 283–293 Table 1 Problem solving course components at McMaster University (from Woods et al., 1997) (a) 1 2 3 4 5 6 7 8 9 10 11
Awareness (1–4 h)‡ What is problem solving? (1 h)‡ Self-assessment (3–6 h)‡ Strategies (1.5–5 h)‡ I want to and I can, stress management (1–2 h)‡ Analysis, classification (2–4 h)‡ Creativity (6–8 h)‡ Introduction to visual thinking, translation (2 h) Define the stated problem (2 h)‡ Getting unstuck (1 h) Identifying personal preference and implications (2 h workshop plus 3 h completing forms)‡ 12 Learning skills (2 h workshop plus 1 h taking notes)‡ 13 Analysis, consistency (1–3 h) 14 Creating the look back and extending experiences (2–4 h)‡ 15 Exploring the situation to identify the real problem (2–4 h)‡ 16 Tactics (2–3 h) 17 Time management for individuals (2–4 h)‡ 18 Evaluation and stress management (1–2 h) 19 More on visual thinking, reading P&IDs (2–5 h)† 20 Asking questions (4–8 h)† 21 Analysis, sequences and series (2–4 h) 22 Broadening perspectives (1–4 h) 23 Obtaining criteria (2 h) 24 Decision making (2–4 h) 23–24a Criteria and decision making in the context of career counselling and guidance 25 Time management for groups and projects (2 h) 26 Listening and responding (a) Attending and following (1 h) (b) Body language (1 h) (c) Reflecting (1 h) 27 Group skills and 28. Group evaluation (90 min–4 h)† (b) 29 30 31 32 33 34 35 36 37 38 38a 39 39a 40
Being an effective chairperson (15 h)* Analysis, reasoning and drawing conclusions (5–7 h) Defining real problems (1.5–4 h) Implementing (2–4 h) Coping with ambiguity (10–15 h)* Trouble shooting (8–10 h)* Heuristics or rules-of thumb for problem solving (3–5 h) Self-directed learning or problem-based learning (1.5–3 h)†* Simplifying and generalising (2–4 h) Consolidating the knowledge structure Consolidating the knowledge structure in chemical engineering (6–8 h) Creating tacit information or experience knowledge Creating tacit information or experience knowledge in chemical engineering (2–4 h) Successive approximation and optimum sloppiness (2–4 h)*
Other units 41 Finding opportunities (1–2 h) 42 Procrastination and other attitudes (2–4 h) 43 Giving and receiving feedback (1–3 h) 44 Assertiveness (2–4 h) 45 Coping creatively with conflict (90 min–3 h)
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Table 1 (Continued) 46 47 48 49 50 51 52 53 54 55 56 57
Coping with difficult behaviours (2–5 h) Accentuating the negative (1–3 h) Communication (30 h) Coping with change (1–5 h)† Being a change agent (3 h) Managing change (3 h) Fundamentals of interpersonal skills (1–5 h)† Effective teams and team building (1–8 h) Goals, mission and vision (4–6 h) Roles and responsibilities in teams (2–3 h) Networking, how to enrich your life and get things done (1–24 h) Convincing others, getting a buy-in (3–5 h)
Core units for course chemical engineering 2G2, development of individual skill in solving reasonably well-defined problems (48 h available with selection from the following units depending on the needs of the students. The usual selections are indicated with a ‡. Chemical engineering 3E4, development of individual skill in solving vaguely-defined, chemical engineering problems (18 h available for the synthesis and application of skills developed in Chemical Engineering 2G2). Core units for course Chemical Engineering 3G3, development of interpersonal skills, lifelong learning and team problem solving skills for open-ended, systems and people problems (24 h available with selection from the following units depending on the needs of the students. The usual selections are indicated with a †. Core units for course chemical engineering 4N4, development of interpersonal skills, lifelong learning and team problem solving skills for ill-defined and open-ended technical and interpersonal problems (30–50 h available with selection from the following units depending on the needs of the students. The * indicates the usual topics with the total hour dependent on the degree to which the activities combine knowledge with MPS skill acquisition. For example, for MPS unit 29, 1 h is devoted to understanding the target skill and the feedback forms; the 14 h is spent in meetings that each person chairs. The meeting can be used to learn the subject knowledge.
gramme!), an extensive set of courses has been developed (see Table 1a and b). One hundred twenty contact hours are available in the undergraduate course in chemical engineering at McMaster to deliver a selection of this material (Woods states that 200 contact h would be required to deliver the entire set of courses). The goals of the McMaster programme are very comprehensive, and clearly go beyond the scope of even a broad definition of process systems engineering education. Nevertheless, significant parts of the course are highly relevant to the development of a systems approach, particularly some of those in the third and fourth year courses (courses 3G3, 4N4). The programme takes a ‘bottom-up’ approach to the development of problem solving skills. The early courses are concerned with individual students working on comparatively well-defined problems. More open-ended problems are tackled in later years, where the nature of the problems often implies a team-based approach. Higgins, Maitland, Perkins, Richardson and Warren Piper (1989), in describing a course on engineering problem solving offered to first-year undergraduates in chemical engineering at Imperial College, identify three
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generic types of problem which engineers are called upon to solve, problems of prediction (e.g. what is the time T taken for a train moving at a steady speed S to travel between stations A and B which are at a distance D apart?); problems of explanation (why are all numbers of the form abcabc (e.g. 791791) divisible by 7, 11 and 13?); problems of invention (devise a method for ensuring that flying aircraft always keep a safe distance from each other). The course focuses on the third type. In a 2-week workshop involving roughly 25 contact h, students are helped to develop and apply a systematic approach to tackling problems of invention. The stated objectives of the course are that, students adopt a convention for stating problems which leads to a systematic way of writing design briefs; students’ creativeness is tapped and manifests itself in a confidence in producing a diversity of solutions to a problem and in avoiding common pitfalls in problem-solving; students can evaluate potential solutions against their brief; solutions are presented in an effective way; students become more effective members of design teams. A simple model of problem-solving is presented, consisting of six stages— defining the problem; conceiving possible solutions; evaluating solutions and choosing one of them; producing the chosen solution; presenting the chosen solution; and evaluating the pro-cess of problem-solving. (There are resonances here with the text of Rudd and Watson discussed in the previous section. Incidentally, it is also interesting to note that Donald Woods was one of the people mentioned by those authors as using their text ‘in its 6arious stages of de6elopment in the uni6ersity classroom’ (Rudd & Watson, 1968)). Students are introduced to the components of the framework and then apply it to realistic engineering problems (e.g. developing proposals for the reduction in the energy
usage of a given plant) during the course of the workshop. 4. The current position In this section, information on the present content of the undergraduate course at Imperial College will be presented, as an illustration of current practice (at least in one department with which the author is familiar) in process systems teaching. The undergraduate programme at Imperial College extends over 4 years, leading to the degree of Master of Engineering (M. Eng.). A high-quality intake of around 80 students enters the first year each year, to be taught by a faculty consisting of just over 30 people (of whom eight are involved in process systems teaching and research). In the first 3 years of the course, the students’ working day is divided into two, with lectures and tutorials confined to one half of the day (typically the mornings). Project work occupies the other half-day. There are no class activities on Wednesday afternoons, to allow students to participate in sports. Thus, in a ‘4-week project’, students are expected to undertake roughly 50 h of work (In practice, they often spend far more time than this!) The first term of the final (fourth) year shows a similar pattern, but in the second term of 11 weeks the students spend most of their time on the final design project. Information on the current core and elective systems courses is shown in Table 2. In assessing the proportion of the total course devoted to systems-related activities, it is worthwhile to note that the first 3 years of the course include 220–235 lectures. The final year contains about 120. Project work runs for between 15 and 20 of the weeks in the first 3 years. On that basis, lecture courses in systems topics contribute roughly 10% of the overall lecture programme, and systems-related projects roughly 40% of the total project load. A student interested enough to take up all elective slots with systems topics would pursue a programme with about 20% systems lectures and approaching 50% systems projects, the elective courses having project work associated with them.
Table 2 Systems components of the current undergraduate programme at Imperial College, London Year of study
Lectures
Projects
First year
Process analysis, 24, lectures text, Felder and Rousseau (1986)
Second year
Process dynamics and control, 30 lectures text, Stephanopoulos (1984)
Third year
Strategy of design, 20 lectures text, Douglas (1988). Elective, Dynamic Behaviour of Process Systems, 40 lectures plus 20 h project work Electives, Advanced Process Synthesis; Advanced Process Control; Stochastic and Adaptive Systems; Flexible Process Operations, all 40 lectures plus 20 h project work
Design, 2 weeks; pilot plant, 3 weeks Process control, 4 weeks; pilot plant, 3 weeks Synthesis/flowsheeting, 4 weeks
Fourth year
Design, 11 weeks (full-time)
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Table 3 Educational objectives of core lecture courses at Imperial College Course and year
Process Analysis, year 1
Process Dynamics and Control, year 2
Strategy of Process Design, year 3
Objectives By the end of the course, students should be able to Quantitatively describe the behaviour of steady-state flow systems in terms of pressures, temperatures, flow rates and compositions Perform steady-state mass balances on an entire process in order to calculate flow rates and compositions within that process system which may include chemical reaction(s), simple separation(s), purge stream(s), recycle(s), and similar complications Perform steady-state energy balances as above, given certain thermodynamic simplifications Assess the economic potential and possible environmental impact of processes, given suitable data Organise themselves into groups which, when faced with a complex problem, can plan a strategy for its efficient solution Derive mathematical models describing the transient behaviour of simple lumped systems in the time domain Derive linearised models from the above mathematical models and use them to deduce the important qualitative features of the transient process behaviour Describe the need for, and the fundamental objectives of, process control for specific applications Describe the relative benefits and limitations of feedback and feedforward control schemes Select and tune simple and cascaded feedback controllers suitable for a variety of common applications Devise and tune simple feedforward control schemes used either in isolation or in conjunction with feedback control Select appropriate control structures for unit operations involving several potential measurements and control manipulations Develop process designs using the Douglas methodology Use computer-based flowsheeting tools as calculational aids in process design problems Apply pinch analysis techniques to the solution of heat exchanger network problems
More details on the core lecture courses are given in Table 3 in the form of the declared educational objectives of each course. Details of the objectives of the design project in first year have been discussed in the previous section. The second and third year design projects are based on open-ended exercises designed to enable students (working in groups) to develop through practice and display the skills involved in the more synthetic elements of the corresponding lecture courses. In second year, the students work on a simulated industrial furnace devising and implementing a process control system. The third year project is based on applying the Douglas method to an example. Students in groups of four go through all stages of the method; flowsheeting tools are available for use at the students’ discretion. The aim of these projects is to prepare students to tackle the final design project in fourth year. There, the students work in larger groups to produce a comprehensive process design involving process synthesis, design of key units, safety and layout, environmental impact, operation and control, and economics. In addition to the design projects in each year of the 4-year programme, students gain practical experience of process control and operation through two pilot-plant projects, one in each of first and second years. The details of these projects have been described elsewhere (Macchietto & Kershenbaum, 1987). A development in the last decade in the UK has been the introduction of 1-year taught Masters programmes,
typically leading to an M.Sc. degree and involving formal lecture-based material combined with a substantial dissertation. An M.Sc. in Process Systems Engineering was introduced at Imperial College in 1996. Five modules, each consisting of 40 lectures and 20 h of project work, constitute the formal part of the course. The current modules are, Dynamic Behaviour of Process Systems; Advanced Process Synthesis; Advanced Process Control; Stochastic and Adaptive Systems; and Flexible Process Operations. These modules also form the elective systems courses offered to undergraduates.
5. The future The development of the curriculum in chemical engineering has benefited in the past from the tension between, on the one hand, imparting to the students a good understanding of the sciences underpinning our discipline and, on the other, the perceived need to help aspiring engineers to develop and enhance the skills necessary to practice as an effective professional. It is my view that a balance between educational activities designed to achieve each of these goals will continue to be an important feature of our discipline if it is to retain its uniqueness. We have seen that addressing the educational objectives associated with the more synthetic aspects of engineering practice was a goal of educators in process
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systems engineering from the earliest days. It is my hope that our community will continue to wrestle with the challenges of helping students to become more effective engineering problem solvers by developing even better courses on the techniques of process systems engineering and their application. In doing so, we should recognise that the opportunities for chemical engineers to apply their knowledge and skills have broadened from the traditional arena of petrochemicals to a whole range of industries where chemical and biochemical transformations are the means to wealth creation. The implication for courses in process systems engineering is that they should seek to be broad in application, emphasising the general rather than the specific wherever possible. The development of courses for chemical engineers in the area of product design (Moggridge & Cussler, 1999; Westerberg & Subrahmanian, 2000) represents one exciting opportunity to broaden the concerns of process systems engineering education in response to these trends. Another area where more pedagogical material could usefully be produced is that of process modelling. The development of appropriate mathematical models of process systems is a synthetic activity. Indeed, many characterise it as an art, in the same way as process design has been characterised in the past. There are current efforts (e.g. at the University of Queensland in Australia (Cameron, 2000)) to develop courses specifically designed to help students to attack the problem of developing an appropriate mathematical model of a process system in a systematic way. The eventual publication of educational materials based on these prototype courses and the widespread introduction of such courses into the core undergraduate curriculum would be a very useful step in terms of developing graduate chemical engineers who will ‘fit for purpose’ in the new millennium. As well as educating our students in systems techniques and tools, we are excellently placed to address the more general educational objectives associated with what I have called in this paper the ‘systems approach’. Indeed, many of you will feel that it is unhelpful to make this division; our goal should be to educate effective professionals who are able to take a systematic approach involving systems thinking, techniques and tools. If reading this paper has encouraged you in that view, then my main objective has been achieved!
6. Conclusions In this paper, I have presented a personal view of the development of process systems engineering education. The development of process design and control teaching has been presented through an analysis of some of the key textbooks that have been published in the past
40 or more years. We have seen that a synthetic element was present even in the earliest systems-orientated process design texts, whereas the most popular early process control texts took a strongly analytical approach. Fortunately, this situation has been recovered to some extent in the past 15 years, and more modern control texts include synthetic material to a greater or lesser extent, offering an instructor discretion in the balance of the course he or she chooses to deliver. Using quotations from some of these texts, I have tried to show that these authors, and others in our community, were concerned with more than the education of students in the use of systems techniques and tools. They also embraced the synthetic nature of chemical engineering, and sought to help students acquire the skills needed to tackle open-ended engineering problems. Indeed, it is probable that these concerns provided one of the motivations for early research in process systems engineering. I have relied on a description of the course at Imperial College to characterise the current situation. It is unlikely that there is such a thing as a ‘typical’ chemical engineering course these days. The discipline shows a healthy diversity in curriculum adopted in different departments, which in my view should be further encouraged. Nevertheless, it is hoped that a description of how one department currently approaches this area in its undergraduate course will be of interest. For the future, in my view it will be important for us to retain and indeed to strengthen the commitment of the pioneers of process systems education to helping our students to develop a ‘systems approach’. Not only should we continue to enhance our students’ education in systems tools and techniques (such as modelling where more systematic courses are on the way). We could also usefully strengthen our courses by contributing to the development of ‘systems thinking’ or the ‘systems approach’ in our students. It is the combination of a strong and broad base in engineering science and the ability to synthesise as well as analyse complex systems that is the unique feature of chemical engineering. The process systems engineering community is the natural keeper of the synthetic component of chemical engineering education. I hope that we will continue to recognise and embrace this responsibility as we develop courses suitable for the chemical engineers of the future.
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