Control loop: Case History 164 - More on valves that do not control properly. January 2019, Michael Brown Control Engineering, Motion Control & Drives I often publish articles showing valve problems. One of the reasons is that I do not think many people understand that valves are generally responsible for 75-80% of all control loop problems. When it ...
Read more...Control loop: Case History 163 - Control limitations on mineral processing plants November 2018, Michael Brown Control Engineering, Motion Control & Drives I was recently asked to conduct a control loop audit on a mineral extraction processing plant which was fairly old and had been acquired by new owners. A new and very modern control system had been installed ...
Read more...Control loop: Case History 162 - Optimising an interesting temperature control. September 2018, Michael Brown Control Engineering, Editor's Choice I have often written about the huge advantages of using cascade control on processes with very slow dynamics. It is particularly useful when it comes to most temperature related processes, which are normally ...
Read more...Control loop: Case History 160 - More problems with control May 2018, Michael Brown Control Engineering, Editor's Choice, Motion Control & Drives In a recent assignment to sort out problems being experienced in a petrochemical refinery, I came across the following two examples: Drum pressure misbehaving
The first was with the control of an ...
Read more...Control loop: Case History 159 - Bad valves again hampering control. March 2018, Michael Brown Control Engineering, Editor's Choice It still fascinates me that so many control problems are caused by poor operation of control valves. I have encountered and recorded hundreds of cases of such problems. What is amazing is that many plant ...
Read more...Cool loop: Case History 158 - Report on temperature control of an autoclave January 2018, Michael Brown Control Engineering, Editor's Choice, Motion Control & Drives I was recently asked to help with a client who treats a product in an autoclave and was complaining that they always got overshoot on a step setpoint change to holding temperature. The following is taken ...
Read more...Control loop: Case history 156 - All problems can be sorted by tuning September 2017, Michael Brown Control Engineering, Editor's Choice People often battle for long periods trying to tune a controller to eliminate problems. As I have often said, one of the biggest fallacies found in plants when it comes to control is that “all problems ...
Read more...Control loop: Case History 155 - Control with unstable tuning July 2017, Michael Brown Control Engineering, Motion Control & Drives I have come across quite a few control loops that were doing a reasonable job of control and which were in fact completely unstable, and in some cases were working much better than if the loop had been ...
Read more...Control loop: Case History 154 - What happens to the process if the valve jumps? May 2017, Michael Brown Control Engineering, Editor's Choice, System Integration & Control Systems Design I recently wrote a Case History about control problems in a minerals extraction plant in Portugal, which was experiencing great difficulty with the control on their flotation banks. I have also written ...
Read more...Control loop: Case History 153 - Why is the control so terribly erratic? March 2017, Michael Brown Control Engineering, Editor's Choice, Motion Control & Drives I was recently asked to advise on a bad pH control problem in a water treatment plant. A new carbonisation bay had been installed at the plant: Figure 1 shows the layout of the bay and controls. Raw water ...
Read more...Control loop: Case History 152 - Control problems with airflows in flotation banks January 2017, Michael Brown Control Engineering, System Integration & Control Systems Design I have written quite a few articles specifically dealing with control problems in mineral processing plants that are largely due to poor understanding, and apparently complete lack of concern of control ...
Read more...Control loop: Case History 151 - The myths surrounding deadtime dominant processes November 2016, Michael Brown Control Engineering, Editor's Choice, System Integration & Control Systems Design The practice of industrial feedback control is one of the most misunderstood engineering disciplines in the world. The theory was developed by eminent mathematicians in the early 1900s and was based on ...
