## Description

So why write yet another book on process control? There are already many published. But they are largely written by academics and intended mainly to support courses taught at universities. Excellent as some of these books are in meeting that aim, the content of many academic courses has only limited relevance to control design in the process industry. There are a few books that take a more practical approach but these usually provide only an introduction to the technologies. They contain enough detail if used as part of a wider engineering course but not enough for the practitioner. This book aims more to meet the needs of industry.

So why write a second edition? Most of the process control techniques covered in the first edition have been in use for decades and will continue to be so for decades to come. While there are ongoing developments in the hardware of control, there is little drive to move away from well‐established techniques. What prompted the second edition was the seemingly never‐ending desire of control engineers to better understand the subject and to explore new ways of applying these techniques. Almost none of the material in the first edition has been deleted; most of it has been expanded with improved explanations and, where valuable, greater depth.

Most engineers responsible for the design and maintenance of control applications find daunting much of the theoretical mathematics that is common in the academic world. In this book we have aimed to keep the mathematics to a minimum. For example, Laplace transforms are only included so that the reader may relate what is in this book to what will be found in most theoretical texts and in the documentation provided by many DCS (distributed control system) vendors. They are not used in any of the control design techniques. And while we present the mathematical derivation of these techniques, to show that they have a sound engineering basis, the reader can skip these if too daunting and simply apply the end result.

This edition has two substantial new chapters. These were added with some trepidation. They appear to be in conflict with the objective of minimising the use of more advanced mathematics. Indeed they have doubled the total number of equations in the book. While the reader may be unfamiliar with some of the mathematical symbols, supporting explanations have been kept simple as possible. These, together with the examples of practical application, should help the more determined readily apply the methods. Those less enthusiastic can however skip these chapters and still be very competent control engineers.

The book aims to present techniques that have an immediate practical application. In addition to the design methods, it describes any shortcuts that can be taken and how to avoid common pitfalls. The methods have been applied on many processes to a wide range of controllers. They should work.

In addition to providing effective design methods, this book should improve the working practices of many control engineers. For example, the majority still prefer to tune PID (proportional, integral, derivative) controllers by trial‐and‐error. This is time‐consuming and rarely leads to controllers performing as well as they should. This might be because of a justified mistrust of published tuning methods. Most do have serious limitations. This book addresses this and offers a method proven to be effective in terms of both controller performance and engineering effort.DCS include a wide array of control algorithms with many additional engineer‐definable parameters.

The DCS vendors are poor at explaining the purpose of these algorithms with the result that the industry is rife with misinterpretation of their advantages and disadvantages. These algorithms were included in the original system specification by engineers who knew their value. But this knowledge has not passed to the industry. The result is that there are substantial improvements that can be made on almost every process unit, surpassing what the control engineer is even aware of – let alone know how to implement. This book addresses all the common enhancements.

This book takes a back‐to‐basics approach. The use of MPC (multivariable process control, or multivariable predictive control) is widespread in industry. Control engineering staff and their contractors have invested thousands of man‐hours in the necessary plant testing and commissioning. Improving the basic controls is not usually an option once the MPC is in place. Improvements are likely to change the process dynamics and would thus involve substantial re‐engineering of the MPC. Thus poor basic control remains the status quo and becomes the accepted standard to the point where it is not addressed even when the opportunity presents itself. This book raises the standard of what might be expected from the performance of basic controls.