As a control engineer, you may get called by plant operators when a PID loop is a “bad actor”, causing problems on a distillation column. The process upset caused by this PID loop may have a destabilising impact on downstream process units as well, potentially causing widespread impact. Quite often, the “quick fix” for process operators is to insert these bad acting PID loops in manual. While this mitigates the immediate issue, the cost of such actions is poor performance of the distillation column. The control engineer is tasked with rectifying the problem. Is this a PID tuning issue or are the PID loops on the distillation column configured incorrectly? How would you ensure that the PID structures on a distillation column are configured correctly? You can read it in this blog.
A split range control strategy uses software or hardware-based splitter and two or more final control elements to control a process variable. You can find split range strategies in different applications across process industries such as temperature control with heating/cooling media, large and small valves installed in parallel, pressure control with a vent valve, etc.
Usually, split range applications are tricky and time consuming, and you should know what I’m talking about as a process control engineer.
Oscillations over the entire range of operation and across the split point, typically improperly selected at 50%, are common in real operation.
This blog will discuss the usual problems you might face when configuring and tuning a split range strategy and the possible and practical solutions to overcome it.
Topics: PID tuning
Every operations manager would like to improve the performance of their asset in a safe manner. You need to steer your plant operation through rapid business changes, and maintain products within the specified targets while always maintaining safe plant conditions. Further optimisation of your operation is not feasible with the current tools, and you know that Advanced Process Control (APC) has been successful in making further improvements in similar processes. How do you go about adopting APC for your facility?
Engineers are often tasked with troubleshooting and resolving process performance issues. The feedback from operators could be statements such as “this PID loop does not work in Automatic” or “I am always getting alarms in this variable” or “this PID loop has never worked in Automatic”. Understanding how to tackle these issues efficiently and effectively requires a systematic approach along with a good PID tuning tool. This blog explains how to go about achieving success in resolving PID tuning issues.
Topics: PID tuning
Buffer tanks are built to provide smoother operation to the process, avoiding the propagation of disturbances on the inputs, e.g., temperature, composition, feed rate, to the downstream process. Aggressive tuning methods don't work for buffer tanks since you want to explore the largest volume possible to reduce the disturbances. In this blog, we will explain how you make a compromise with the correct tuning.
Topics: PID tuning
Every DCS has its own set of PID loop equations. A Honeywell Experion DCS features 5 different equations and an Emerson Delta-V DCS can even offer 7 equations. Each equation implies a different formulation of the PID control algorithm. So, each equation might require different tuning parameters to obtain the same or similar closed-loop behaviour. Many control engineers ignore the equation type of a PID loop. Even if you have tuned many different loops, you might not be able to obtain the desired closed-loop performance if you don’t have the right equation selected.
The tuning of Proportional-Integral-Derivative (PID) can be considered a mix of art and science. It's an art where one needs to use their judgment and experience to understand the controller’s behavior. The science of tuning comes into the picture where one uses open-loop mathematical models and different techniques to derive the tuning parameters. The “Art” of tuning helps to understand the how’s and why’s of the process, and the “Science” of tuning provides a roadmap for tuning.
The performance of any PID controller depends on tuning parameters, i.e., gain, integral time, and derivative time that is set in. The tuning parameters are a function of process types, functionality expected from the PID loop, i.e., variance reduction or setpoint tracking, and type of the PID loop.
Topics: PID tuning methods
Advanced Process Control (APC) carries a raft of benefits. Any competent control engineer can list at least a dozen. That list will often contain only quantitative benefits - emphasizing production yields, feedstock flows, product qualities and the like. There are however also other benefits to advanced process control - benefits less strictly numeric, but nonetheless with a huge impact on operating efficiency.
Topics: Advanced Process Control
As a production manager, you have one main goal: optimal and stable operations. You need to reach your production targets while taking care of the plant’s efficiency and safety. Optimal functioning of the entire production process in its broadest sense — achieving objectives for safety, quality, quantity, costs, environmental impact and reliability — is your responsibility. A low cost way t boost process performance therefore may seem like the holy grail.
In this blog, we'll describe 6 ways how PID Tuning boosts plant performance. Are you curious about this holy grail yet?
Steam drum is a vital part of boiler system in chemical industries. Proper and safe functioning of boiler depends on various parameters such as level of steam drum, flow of feedwater and flow of steam. The pressure, temperature and level of boiler system cannot be regulated directly but depends on the feed-water flow. The pressure or temperature in a boiler system can be maintained by controlling the flow of fuel and air whereas the level can be maintained by regulating the flow of feed water. The purpose of drum level controller is to keep the level at desired value, optimal interface level requires between steam and water within the steam drum. It is essential that the level of liquid must be low enough to assure that there is appropriate separation between steam and water and high enough to guarantee that the water exists in every steam generating tube.
In this blog we will show the 3 most common drum level control schemes and what tuning strategy you should adopt for every strategy.