By Jim Riggs1 In the first article of this series, Jim discussed control relevant issues associated with distillation columns. The second article presented the major disturbances affecting composition control and […]
By Fred Thomasson1 In the Control Magazine article entitled Envelope Optimization by Bela Liptak (www.controlglobal.com; 1998), a multivariable control strategy is described whereby a process is “herded” to stay within […]
By Peter Nachtwey1 Since most of us don’t have our own heat exchanger to test on, I thought it would be good to show how one can be simulated. This […]
By Jim Riggs1 In the first article of this series, Jim discussed control relevant issues associated with distillation columns. The second article presented the major disturbances affecting composition control and […]
By Jim Riggs1 In the first article of this series, Jim discussed the importance and challenges associated with distillation control and the control relevant issues of distillation operations. Here he […]
By Jim Riggs1 Background Approximately 40,000 distillation columns are operated in the U.S. chemical process industries and they comprise 95% of the separation processes for these industries. Because distillation operation […]
By Allen D. Houtz 1 My objective is to continue the discussion we began in the article Cascade, Feed Forward and Boiler Level Control. Here we explore the causes and […]
By Allen D. Houtz 1 One common application of cascade control combined with feed forward control is in level control systems for boiler steam drums. The control strategies now used […]
By Allen Houtz1 and Doug Cooper We explored override control using select elements in a previous article and learned that environmental and energy efficiency concerns for metered-air combustion processes can […]
By Allen Houtz1 and Doug Cooper A select element receives two input signals and forwards one of them onward in the signal path. A low select, shown below to the […]