Case History 150: Mystery in distillation column temperature control. September 2016, Michael Brown Control Engineering, Editor's Choice The longer I work in the field of control loop optimisation, the more I learn that things often do not work the way one expects. I have spent over 30 years optimising literally thousands of feedback control ...
Read more...Control loop: Case History 149 - Classic examples of badly optimised loops. July 2016, Michael Brown Control Engineering, Editor's Choice Problems on a flow control loop The first example is that of a flow control loop on a liquid flow. Figure 1 shows a closed loop test with a step change of setpoint.
Three problems immediately stand ...
Read more...Control loop: Case History 147 - Why base-layer feedback control is needed April 2016, Michael Brown Control Engineering, Editor's Choice, System Integration & Control Systems Design A friend of mine was appointed to start an advanced control and optimisation group in a very large chemical plant and he hired a group of academically highly qualified young APC (advanced process control) ...
Read more...Case History 146: What makes control loop optimisation worthwhile? February 2016, Michael Brown Control Engineering, Editor's Choice, System Integration & Control Systems Design In this article we look at three cases where great success was achieved through optimisation. The work was all done in a petro-chemical refinery. Case study 1
The first example is of a reactor feed ...
Read more...Control loop: Case History 145 - Control problems in a zinc mine December 2015, Michael Brown Control Engineering, System Integration & Control Systems Design As a break from the problem reports presented in the last few Case Histories, this article will discuss some problems I encountered recently at a zinc mining plant in Europe where I carried out a base ...
Read more...Case History 144: Report after optimisation exercise – part 5 October 2015, Michael Brown Control Engineering, System Integration & Control Systems Design This is the fifth article taken from a report which was prepared for various departments in a process company after some optimisation work was performed for them. (The other four articles were published ...
Read more...Control loop: Case History 143 - Report after optimisation exercise – Part 4. August 2015, Michael Brown Control Engineering, System Integration & Control Systems Design This is the fourth article taken from a report which was prepared for various departments in a process company after some optimisation work was performed for them. (The other three articles were published ...
Read more...Control loop: Case History 142 - Report after optimisation exercise – Part 3. June 2015, Michael Brown Control Engineering, System Integration & Control Systems Design, Editor's Choice This is the third article taken from a report which was prepared for various departments in a process company after some optimisation work was performed for them. (The other two articles were published ...
Read more...Control loop: Case History 140 - Report after optimisation exercise February 2015, Michael Brown Control Engineering, System Integration & Control Systems Design There is a particular continuous process plant in South Africa that takes base layer control loop optimisation extremely seriously. (Many other plants unfortunately do not, which to me is terribly sad.) ...
Read more...Control loop: Case History 139 - The importance of measurements and dynamics. November 2014, Michael Brown Control Engineering, System Integration & Control Systems Design One of the first laws of process control states that you cannot control what you cannot measure. However, although instrument practitioners all know this they very often forget it.
I think this is largely ...
Read more...Control loop: Case History 138 - Bad actors. September 2014, Michael Brown Control Engineering, System Integration & Control Systems Design Alarm management has become a subject of interest in many plants. With the advent of computerised control and HMI systems, it has become extremely easy to put alarms onto control loops. Nowadays operators ...
Read more...Control loop: Case History 137 - The cycling pressure loop. July 2014, Michael Brown Control Engineering, System Integration & Control Systems Design I have written much in the past about the peculiar problems inherent to integrating processes. The most commonly found of these are level controls, but some pressure control loops, particularly those ...
Read more...Control loop: Case History 136 - Control valve with negative hysteresis May 2014, Michael Brown Control Engineering, System Integration & Control Systems Design Following on the theme of Case History 135, here is another example of what a really bad valve can do to contribute to problems in control loops.
The example is of a loop controlling the reflux flow ...
