Ender, President, Techmation, Inc. Reprinted from Control Engineering September Twenty-five years ago, control systems were built around single loop pneumatic controllers, pneumatic transmitters, and control valves. These were hooked together with pneumatic tubing carrying psi pneumatic signals that implemented control strategies at the speed of sound. Controllers were either proportional only P or proportional plus integral PI. Derivative cascade, and feedforward were viewed as very advanced control strategies. Controller tuning was considered more of an art than a science and the subject of active research at many universities.
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Aug 31, Covering 10 million American homes with solar roofs would trigger the biggest economic expansion of the decade. Distillation, Part 5: Multiple Products Aug 1, In Part 5 of this series on distillation control and optimization, we find that adding a side-stream component to your process gives an additional degree of freedom, but makes it even more essential to not mismatch the variables.
What are the potentials of process control in wind, ocean wave, and geothermal energy systems. How to select control valves, Part 2 Sep 12, When it comes to selecting and sizing control valves and positioners, this article not only helps you pick the right one for the right job, but also includes a valuable valve selection chart you can download!
How to select control valves, Part 1 Jul 14, When it comes to selecting and sizing control valves, the non-commercial chart in this article not only helps you pick the right one for the job, but also serves as a fantastic reference tool you can download!
Why do we have global warming? Can process control help stabilize global warming? A process only mankind can control Jan 9, Global warming, devastating hurricanes and rising ocean currents are all signs of a presently-out-of-control global heat balance that may result in colder winters and our summers permanently disappearing. Can an automation engineer control the economy?
The next generation of smarter valves May 10, In the next decade, much improvement and change is expected in the design of smart and self-diagnosing control valves, with potential advantages outweighing the required investment of time and money. The fuel cell: A new process to control Sep 20, The fuel cell is like a battery, except that it never needs recharging because the heat and electricity produced by it are made from the inexhaustible and clean sources of water and air.
Instrument Engineers' Handbook, Vol. 2: Process Control and Optimization, 4th Edition
He can be reached at liptakbela aol. In process control, there are at least five levels of sophistication that the automation engineer can apply. The advantage of the higher levels is better control, but applying a higher level also requires better understanding of the process. In the analog age, using higher levels of sophistication also involved substantially higher costs, but in the digital age, this consideration has become less significant. To illustrate the five levels, I will use the example of controlling the outlet temperature from a steam-powered liquid heat exchanger. Manual Control Figure 1 : Manual feedback control is performed by the operator by watching the hot water temperature and manually throttling the steam flow to keep this outlet temperature constant. Manual feedforward control is performed when the steam flow is throttled on the basis of the temperature and flow of the incoming cold water.
Béla G. Lipták
Books by Béla G. Lipták