Myke King and the Myths of Process Control

  • ChemPubSoc Europe Logo
  • DOI: 10.1002/chemv.201000081
  • Author: Anja Stephan
  • Published Date: 24 May 2011
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
thumbnail image: Myke King and the Myths of Process Control

Myke King is the founder and director of Whitehouse Consulting, UK,  an independent consulting organization specializing in process control. He has over 35 years experience working with over 100 clients from more than 30 countries. As part of his consulting activities, Myke has developed training courses covering all aspects of process control. To date, around 2,000 delegates have attended these courses. To support his consulting activities he has developed a range of software to streamline the design of controllers and to simulate their use for learning exercises.


Anja Stephan took the opportunity to speak to him on behalf of ChemViews about process engineering and his new book, Process Control: A Practical Approach.


Mr. King, how would you describe the topic of process control to someone who has no experience in the field?

Any manufacturing process has key variables that must be held at required values. In the process industry, for example, we need to control such things as flow, temperature, and pressure. Process control encompasses the hardware and software necessary to control such variables. The hardware is generally described as ‘instrumentation’ and ‘control system’. There are specialists in each of these fields. Process control, as described in the book, is more to do with algorithms which reside in the control system. These determine what adjustments must be made to the process to operate at the correct conditions.


However, this simple explanation does not do justice to the breadth of the subject. The range of available control algorithms is always growing and these days we can measure or infer many other process variables, such as product composition or how close we are to operating constraints. Higher levels of control can actually decide what the optimum operating conditions should be.


Why is the topic so important?

First and foremost we have to ensure that any manufacturing process is stable, safe, and operable with a sensible number of staff. It is the job of the process designer, supported by process control experts, to ensure this is the case. However, process control also offers huge opportunities to improve the profitability of the process. We can use it to drive the process right up to its operating limits without jeopardizing its integrity. We might, for example, be able to increase production substantially beyond design. We can reduce operating costs by increasing product yield or by saving energy. We can more closely control the quality of the product and we can improve process reliability.


How is process control changing and where is the field heading?

As with any technology, there are occasional step changes to the techniques applied. When I entered the profession process control applications were configured using standard algorithms available in the control system, supported by custom code where necessary. This has since been named ‘traditional’ process control. Although effective, schemes could become quite complex and this limited what could be achieved.


In the mid-1980s multivariable control (MVC) packages started to become commonplace. There is no doubt that these have had a major impact on process profitability and will continue to do so. But they bring disadvantages also — most notable of which is that they can appear extremely complex to the process operator. There is a growing belief that they have gone too far in replacing easier to understand traditional techniques and that a better approach is to combine both approaches. The problem is that expertise in the traditional techniques is now quite rare.


You are Director at Whitehouse Consulting, Isle of Wight, UK, and before this had several positions in process control. When did your interest in process control begin?

I entered the process control profession almost by accident. I graduated as a chemical engineer and process control was included as one of the course modules. I really disliked the subject and would never have considered following it in industry. But, when attending a job interview I met another candidate who had just been interviewed by Esso. He had been asked whether he might be interested in joining their process control section. He’d declined but the job they’d described sounded ideal for me. I called them the next day, had an interview and was offered the job on the spot. It turned out (fortunately!) to be completely different from what the highly theoretical content of university courses would lead one to expect.


What do you enjoy most about your career?

I’ve been working as a process control engineer for most of the 35 years since graduating. It’s probably the only part of chemical engineering where the engineer can have a direct and immediate impact on process performance. For example, engineers involved in process design may have to wait several years for the process to be commissioned and may never see how well it performs. Even those involved in providing technical support to existing processes generally have their recommendations implemented by others.


It is tremendously satisfying to develop an idea, implement it and make a noticeable impact on process performance — especially in some cases when this might all be completed within a day!


What inspired you to write the book ‘Process Control: A Practical Approach’?

It was simply that there was no book that truly showed how to apply the process control techniques that are available as standard in most control systems. System vendors have, over the last 40 years or so, been developing the algorithms that are now available. But often only the development team understood their purpose. This knowledge has not been passed to the vendors’ technical support personnel — let alone to their customers. The result is that the process industry is generally unaware of what these systems can achieve and how to achieve it. One can pretty much guarantee that a review of the control schemes on any process would reveal several opportunities where improved control design would make a substantial improvement to profitability.


So, is your book more relevant for industry or universities?

Most books on this subject are written by academics and are intended to support highly theoretical courses taught at universities. There are some excellent books of this type, but they have only limited relevance to practical application in industry. A few academics have attempted to make their courses more relevant. However, process control is usually only a small module in the much wider subject of chemical engineering. These books can only provide an introduction to the subject. Mine goes into sufficient depth to more closely meet the needs of industry — although it would be great to see parts of it used in university courses.


Is it true that many people are put off the subject after studying it at university? Why do you think that is?

I’m proof that this happens! At university I struggled with most of the mathematics and could not see its relevance. I did what most students do — ignore the subject and focus on the other course modules to obtain my degree in chemical engineering. Even as a convert, running the process control section for my first employer, I had tremendous difficulty recruiting new graduates into the field. We resolved this by taking over part of the university’s course, showing students what the subject really entailed. That was over 30 years ago, but the problem still exists throughout the world.


Chemical engineering students are still faced with daunting techniques such as Bode plots, Nyquist diagrams, Laplace transforms, etc. While some may be relevant to other engineering disciplines, most have little relevance to process control. And those that are useful are better taught after graduation, once the engineer has had at least a little practical experience. The approach taken in the book was to try to avoid their use completely. However, for those wanting to make the link between theory and practice, more details are included at the end of each chapter.


The book claims to minimize the use of daunting mathematics. How have you managed to do this for a topic which essentially involves a lot of equations?

The use of some mathematics is unavoidable. For example, the control engineer needs to know the underlying formula of the chosen control algorithm and be able to make the calculations necessary to properly tune the controller. But the equations included should be well within the capabilities of someone who has learnt mathematics up to high school level. And much of the mathematics can be skipped if the reader is happy to just apply the end result without necessarily understanding how it was derived.


The book is also arranged so that more complex and process-specific techniques are in the later chapters. Even the most daunted reader should find value in the first half of the book and, after applying these techniques, feel more comfortable progressing with the remainder.


You’re also involved in running training courses on process control. How has this experience enriched the content of the book?

The book is derived directly from the training courses. I have been involved in training control engineers for over 30 years. The current courses were first developed 20 years ago and have been attended by around 2,000 engineers. Every time the courses are run we find ways of improving them. We learn how to better cover the more tricky concepts with which some students may have struggled.


The engineers all come from industry; we learn from them the practical difficulties they have encountered so include solutions in future courses. This, combined with working on processes as part of my consulting activities, means the course material (and therefore the book) is up to date, identifies real opportunities to improve process performance, and provides designs proven to work well.


What was most interesting about writing the book?

Like many control engineers, I had always taken at face value many of the techniques presented in text books and papers. When writing the book I checked, for reference purposes, the original quoted source. I was surprised by how much the original had been distorted — presumably by an accumulation of small changes and omissions arising from authors not working from the original source.


Indeed, writing a book taught me it is almost impossible to produce one that is completely free of errors. But the subject of process control is now rife with myths about which control algorithm to select and how to tune them. In addition to showing how things should be done, I’ve also described these surprisingly common errors.


Which part of the research for your book was the most interesting for you personally?

While most books published on the subject are highly theoretical and generally too complex for an engineer to find them of practical help, many do contain valuable snippets. The challenge was to identify these and present them in a more practical form. It was quite satisfying to uncover a little-known technique and modify it to make it a practical addition to control engineering.


What is your no. 1 piece of advice for anyone new entering the process control industry?

Research carefully the various areas that make up process control before deciding where to specialize. Instrument engineering tends to suit those with more of an electronics background. Control systems engineers are more akin to computer systems engineers. Process control application engineers, like myself, tend to have a background in chemical engineering because they need the sound understanding of the process and its economics. But there are no hard and fast rules; there are many successful engineers working in the field that developed their expertize no matter what their background.


Myke King graduated from Cambridge University, UK, with a Master's degree in chemical engineering. On graduating, he joined the process control section at Esso's refinery at Fawley, UK. He later became head of the process control section and then moved to operations department as a plant manager. This was followed by a short period running the IT section.


King left Esso to co-found KBC Process Automation, a subsidiary of KBC Process Technology, later becoming its managing director. The company was sold to Honeywell where it became their European center of excellence for process control. At this time, King set up Whitehouse Consulting.


Myke King is a Fellow of the Institute of Chemical Engineers in the UK. He lives on the Isle of Wight, UK.


Click here to visit Myke’s website.



Process Control: A Practical Approach

Myke King,
John Wiley & Sons, Chichester, UK
2010.
ISBN: 978-0-470-97587-9






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