The following tip is from the ISA book by Greg McMillan and Hunter Vegas titled 101 Tips for a Successful Automation Career, inspired by the ISA Mentor Program. This is Tip #54, and was written by Greg.
You can pursue your own PCI initiative by estimating the monetary value of your ideas. Tip #59, Tip #61 and Tip #62 can help. Warning! If you are successful, you may have to put on a suit and dress shoes to make a presentation at a board meeting. You may be forced to eat French pastries and caviar. If this happens, you can do us all a favor if you can get the following quote by you into the Wall Street Journal:
Automation systems tell us what is going on in the process and provide the means for us to continuously maintain the process at its best. Automation professionals are in the best position to improve company profitability and shareholder return.
oncept: You need to show the impact on the bottom line to be given the freedom and resources to do more than simply execute control definition projects that were developed by Process Design and Operations. Track down the sources of variability. Get with the process engineers and make simple calculations of the cost or profit opportunities. Use innovative strategies to achieve process improvement objectives and reduce energy, raw material, recycle, and waste treatment costs and increase on-stream time and production rate. Take advantage of new automation system tools and functionality.
Details: Become buddies with a process engineer and confidant of the operators as per Tip #51 and Tip #52. Track down the sources of variability, starting upstream and looking for oscillating loops, on-off control, and manual actions. Use auto-tuning and adaptive tuning tools to improve loop tuning. Use the power of the PID to eliminate on-off control and operator intervention. Eliminate manual control per Tip #69 by automating the best of the operator actions and replacing the scheduling of flows with feedback control (e.g., fed-batch control and automated start-ups).
Move on progressively to important unit operations, perhaps starting (for example) with reaction and continuing on with crystallization and separation and ending up with blending and drying. Add override control and valve position control for small optimization opportunities or model predictive control for large optimization opportunities. Finally, take a look at waste treatment system efficiency. Compute online metrics (Tip #61). Use key PID features (Tip #71, Tip #72 and Tip #100) to reduce interactions, coordinate loops, eliminate trips, reduce off-spec material, protect equipment, and optimize loops. Use a virtual plant (Tip #99) to do experimentation to find and quantify possible improvements.
Watch-Outs: Large equipment volumes will smooth out upstream oscillations, similar to the attenuating effect of an electronic signal filter on noise. Here the filter time constant is the volume residence time (volume/flow). This filtering action must be considered when estimating the cost of variability downstream. Don’t get hung up on actual cost numbers. If necessary, use percentages. The relative improvement and technology are what is important. Operator training and handholding are essential, or else whatever is new will be blamed for anything that goes wrong.
Exceptions: If a feed or utility valve is wide open there is not much you can do to increase production rate if downstream variability is acceptable. Large blend tanks can keep material within spec despite upstream variability. If there are only on-off valves, you are relegated to improving sequences until control valves and PID loops are installed.
Insight: You need to be able to estimate and demonstrate the value of improvements in process efficiency and capacity in order to get a commitment of time and money for process control innovations.
Rule of Thumb: Estimate the benefits from a decrease in variability and an increase production rate and implement solutions where the increase in plant profitability provides sufficient justification.
About the Author
Gregory K. McMillan, CAP, is a retired Senior Fellow from Solutia/Monsanto where he worked in engineering technology on process control improvement. Greg was also an affiliate professor for Washington University in Saint Louis. Greg is an ISA Fellow and received the ISA Kermit Fischer Environmental Award for pH control in 1991, the Control magazine Engineer of the Year award for the process industry in 1994, was inducted into the Control magazine Process Automation Hall of Fame in 2001, was honored by InTech magazine in 2003 as one of the most influential innovators in automation, and received the ISA Life Achievement Award in 2010. Greg is the author of numerous books on process control, including Advances in Reactor Measurement and Control and Essentials of Modern Measurements and Final Elements in the Process Industry. Greg has been the monthly "Control Talk" columnist for Control magazine since 2002. Presently, Greg is a part time modeling and control consultant in Technology for Process Simulation for Emerson Automation Solutions specializing in the use of the virtual plant for exploring new opportunities. He spends most of his time writing, teaching and leading the ISA Mentor Program he founded in 2011.
Hunter Vegas, P.E., holds a B.S.E.E. degree from Tulane University and an M.B.A. from Wake Forest University. His job titles have included instrument engineer, production engineer, instrumentation group leader, principal automation engineer, and unit production manager. In 2001, he joined Avid Solutions, Inc., as an engineering manager and lead project engineer, where he works today. Hunter has executed nearly 2,000 instrumentation and control projects over his career, with budgets ranging from a few thousand to millions of dollars. He is proficient in field instrumentation sizing and selection, safety interlock design, electrical design, advanced control strategy, and numerous control system hardware and software platforms.