Reactors are the pivotal unit operation that sets plant capacity and efficiency besides product quality. Reactors provide good examples of the common and distinctive opportunities for the PID control of batch, fed-batch, and continuous unit operations. Here we examine pressure, temperature, and endpoint control. The pressure control of batch, fed-batch, and continuous reactors may have …
Category Archive: Advanced Control
Sep
01
Chance of a Lifetime
We have the opportunity to hear the 3 most influential and knowledgeable technical leaders in industry give their assessment of the present state and future of our profession. This will be the first and most likely only time these guys will be sharing their knowledge at the same event, thus covering the complete spectrum of …
Aug
29
Commissioning Control Systems – Process Delay
Single-loop and multi-loop control may be used to address a wide variety of control requirements. However, if a process is characterized by extremely long process delays or by a high degree of process interaction, then other control techniques may be required. The control of quality parameters such as composition is often complicated by large process …
Aug
22
Commissioning Control Systems – Control Response
In many processes, it is desirable to have an overdamped response. To achieve that response, the proportional gain used in the PID is typically much less than that required for an underdamped or unstable response. When selecting the PID gain, it is important to consider that the process gain may change with the operating conditions. …
Aug
15
Commissioning Control Systems – Process Interaction
In many applications, the process equipment is characterized as having multiple manipulated inputs. This type of equipment configuration is often referred to as a multiple input/multiple output process. The process control consists of multiple PID blocks where a process output and process input pair are associated with each PID. The challenge in designing and commissioning …
Jul
21
Top Ten Limitations – Analyzers
Ultimately what we most need to know in each key process stream is the operating condition least measured; composition. We are largely flying blind. Neural networks and projections to latent structure technologies have proliferated because online and at-line analyzers are missing. Here is a look at the use of analyzers in the process industries. Advanced process control (APC) …
Jul
15
Top Ten Limitations – Setpoints
A loop is only as good as its setpoint. Most loops are not operating at the best setpoint for 9 major reasons. For sustainable manufacturing we need to understand and address these reasons to achieve better setpoints to reduce the energy, raw material, recycle, and waste and provide more flexible production while maintaining product quality. Reducing …
Jun
23
Top Ten Limitations – Value Analysis
Automation engineers don’t get anywhere near the credit they deserve for increases in process performance. The value would be obvious if the automation system could be turned off but no one would allow this capture of the “before” and “after”. We need to do a better job of documenting where we are and could be. …
Jun
17
Top Ten Limitations – Communication
Every time I see associates retire, I have mixed emotions. I am happy to see them enjoy more R&R, but I am sad to see their expertise go. Very few users have had the time or support to communicate what they have learned the hard way by field experience. When they go out the door, …
Jun
06
Addressing Difficult Dynamics, Process Interaction
Single-loop and multi-loop control may be used to address a wide variety of control requirements. However, if a process is characterized by extremely long process delays or by a high degree of process interaction, then other control techniques may be required. In Chapter 16 of Control Loop Foundation – Batch and Continuous Processes, pulp bleaching …
