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Computer control in the process industries
Book Computer
Control
in
ROFFEL and PATRICK Sea, 257 pp.. f54.75
Process Industries. By BRIAN CHINN. Lewis Publishers, Leigh-onthe
The authors have recognised the ueed for a book which would assist engineers involved with computer control of processing plant. According to the publishers, they both graduated in chemical engineering from McMaster, bott worked as computer applications engineers for,Esso Chemi cal Canada and now work for Polysar Ltd. The first five chapters, representing about 25% of the text, deal with computers, control networks. control software, system selection and reliability. There is then a short chapter on batch and continuous control before advanced control is introduced in Chap. 7. The following I1 chapters include material on dead time compensators. feed-forward, interaction and decoupling, constraint control, process models, optimization, self-tuning and adaptive controllers, state observers and Kalman filtering. The first chapter of the control section starts by introducing a model of a simple well-stirred tank which leads directly to the concept of a continuous system transfer function; then 2 transforms are thrown before the reader, followed by digital simulation and PID tuning guidelines. This typifies the confusion of approach which is apparent in much of the rest of the book. The authors have not been able to agree on the minimum level of attainment or experience which they expect of their readers. At different points in the book they assume no background ofcontrol theory. whileelsewhere it is clear that a sound grasp of block’ diagram manipulations and state variable manipulations is expected. The succeeding chapters on the various control techniques are well written,
Reviews
2913
although some of the theory, particularly in the chapters on state observers and Kalman filtering may prove indigestible to practically oriented engineers. In other chapters, the writer does give examples from several different applications to illustrate the approaches described, though these do have the strong distinctive taste of the petrochemical industry. The early chapters on computers and computer systems in control are an irritating combination of fine detail and sweeping generalization. There are some unfortunate misorderings of topic; for example although the authors raise the question on p. 37 in connection with computer selection, whether direct digital control can be changed to setpoint control, they do not actually explain the distinction between the two until p. 45. Some topics, including system security, hierarchies and distributed systems are covered only at a most superficial level. Readers must also be prepared to accept that in these early chapters the book has been laid out so that diagrams and tables referred to on one page seem often to be overleaf. This book does aims to cover a rapidly developing field and several of the chapters provide useful material which is not as well covered elsewhere. It- suggests that process engineers can use their chemical engineering knowledge to set up computer systems by running process calculations online to ensure that a process always operates optimally, but. alas, fails to make it clear that this can often be done without the specialist’s knowledge of control theory. J. D. BOYLE Drpartntrnt of Chemical Enginrrriny Unicwrsity of Exeter North Park Road, E.ueter EX4 4QF,
U.K.
Control
in
ROFFEL and PATRICK Sea, 257 pp.. f54.75
Process Industries. By BRIAN CHINN. Lewis Publishers, Leigh-onthe
The authors have recognised the ueed for a book which would assist engineers involved with computer control of processing plant. According to the publishers, they both graduated in chemical engineering from McMaster, bott worked as computer applications engineers for,Esso Chemi cal Canada and now work for Polysar Ltd. The first five chapters, representing about 25% of the text, deal with computers, control networks. control software, system selection and reliability. There is then a short chapter on batch and continuous control before advanced control is introduced in Chap. 7. The following I1 chapters include material on dead time compensators. feed-forward, interaction and decoupling, constraint control, process models, optimization, self-tuning and adaptive controllers, state observers and Kalman filtering. The first chapter of the control section starts by introducing a model of a simple well-stirred tank which leads directly to the concept of a continuous system transfer function; then 2 transforms are thrown before the reader, followed by digital simulation and PID tuning guidelines. This typifies the confusion of approach which is apparent in much of the rest of the book. The authors have not been able to agree on the minimum level of attainment or experience which they expect of their readers. At different points in the book they assume no background ofcontrol theory. whileelsewhere it is clear that a sound grasp of block’ diagram manipulations and state variable manipulations is expected. The succeeding chapters on the various control techniques are well written,
Reviews
2913
although some of the theory, particularly in the chapters on state observers and Kalman filtering may prove indigestible to practically oriented engineers. In other chapters, the writer does give examples from several different applications to illustrate the approaches described, though these do have the strong distinctive taste of the petrochemical industry. The early chapters on computers and computer systems in control are an irritating combination of fine detail and sweeping generalization. There are some unfortunate misorderings of topic; for example although the authors raise the question on p. 37 in connection with computer selection, whether direct digital control can be changed to setpoint control, they do not actually explain the distinction between the two until p. 45. Some topics, including system security, hierarchies and distributed systems are covered only at a most superficial level. Readers must also be prepared to accept that in these early chapters the book has been laid out so that diagrams and tables referred to on one page seem often to be overleaf. This book does aims to cover a rapidly developing field and several of the chapters provide useful material which is not as well covered elsewhere. It- suggests that process engineers can use their chemical engineering knowledge to set up computer systems by running process calculations online to ensure that a process always operates optimally, but. alas, fails to make it clear that this can often be done without the specialist’s knowledge of control theory. J. D. BOYLE Drpartntrnt of Chemical Enginrrriny Unicwrsity of Exeter North Park Road, E.ueter EX4 4QF,
U.K.