Essentials of Modern Measurements and Final Elements in the Process Industry: A Guide to Design, Configuration, Installation, and Maintenance

Preface

This book gave me a chance to get back to my instrumentation roots. I spent the first seven years of my career in the field as an instrument design and construction engineer. I was responsible for the calibration, installation, and commissioning of instruments for a half-dozen plants, where I became painfully aware that the actual performance of the process measurements and control valves (the most prevalent type of final element) was largely unknown. These were the days before the advent of smart instrumentation. We didn’t know the effects of stiction and backlash on control valves or the effects of impulse line, process, and ambient conditions on measurements. We didn’t know the performance of measurements and control valves that were installed in industrial plants greatly differed from catalog information. We shifted set points and just shook our heads when the material and energy balances did not close. At the time the plants could sell everything produced. Since we were mostly interested in capacity we just pushed on to make more product. Operating efficiency and turndown were not a primary concern, which was fortunate because we didn’t have the speed of response and accuracy of “today’s” instrumentation needed for measuring and improving process performance and tracking down valve problems.

I then moved into engineering technology where I had the chance to develop an expertise in solving difficult problems in particularly challenging loops. I spent most of the 1980s working on pH, furnace pressure, and compressor surge loops, which were the ultimate test of measurement and valve performance.

My perspective on the importance of field devices was solidified in the 1990s, when I was part of a corporate-wide process control improvement program. Most of the opportunities involved tuning control loops and adding feedforward control for continuous processes and feedback loops for fed-batch operations. However, a lot of great ideas “fell by the wayside” because of missing or imprecise measurements and inadequately responsive valves.