We ask Russ:
What are the pros for empirical models?
Russ' Response:
I would broadly classify models as empirical or phenomenological.
Empirical models are developed by matching flexible mathematical functions to data. The functions might be neural networks, or classic statistical...
We ask Greg:
What role do you see dynamic simulation playing in the future of best dryer temperature control?
Greg's Response:
The basic loop arrangement for dryer temperature control would use cascade control of outlet temperature to set inlet temperature. However, a constant outlet...
We ask Julie:
How has simulation contributed to operator training and control strategy development in your organization?
Julie's Response:
Many years ago, one site had an incident where an interruption in the flow of an organic fuel led to a deflagration. As a result, the operators always ran...
We ask Russ:
Why use phenomenological models based on first principles over data-based modeling options?
Russ' Response:
I would broadly classify models as empirical or phenomenological.
Empirical models are developed by matching flexible mathematical functions to data. The functions...
We ask Greg:
What role do you see dynamic simulation playing in the future of best kiln and calciner temperature control?
Greg's Response:
In kilns and calciners, there are typically four zones. First is a drying zone of constant temperature, followed by a heating zone of rising temperature...
We ask Julie:
What strategies have you found effective for starting small, low-risk simulation projects to build credibility and trust?
Julie's Response:
Back in 2019, the new DuPont was formed after the merger and split with Dow. Many sites were struggling to continue their migration projects...
We ask Greg:
What role do you see dynamic simulation playing in the future of best vessel temperature control?
Greg's Response:
A vessel is defined here as storage, recycle, blend, or surge volume where there is no heat of reaction and no agitator. Fortunately, most vessel volumes are so large...
We ask Russ:
What are some of the benefits of dynamic simulation over steady state simulation?
Russ' Response:
Traditionally, process design uses steady state (SS) simulation, and it serves its purpose well. Most analysis of processes and textbook instruction on how processes work use SS...
We ask Greg:
What role do you see dynamic simulation playing in the future of best heat exchanger temperature control?
Greg's Response:
Flows much lower than design causes a high process gain and high process deadtime that can lead to temperature oscillations and possible instability. Low...
We ask Greg:
What role do you see dynamic simulation playing in the future of best temperature measurement installation?
Greg's Response:
Temperature RTD sensors should use 4 wires and TC sensors should use extension wires of same material as sensor with length as short as possible to minimize...
We ask Greg:
What role do you see dynamic simulation playing in the future of best temperature measurement selection?
Greg's Response:
Temperature is often the most important of the common measurements because it is an indicator of process stream composition and product quality. Temperature...
We ask Greg:
What role do you see dynamic simulation playing in the future of best lime system design for pH control?
Greg's Response:
Lime feeders have a transportation delay that is proportional to the length of the feeder divided by its speed. This transportation delay may be several...
We ask Greg:
What role do you see dynamic simulation playing in the future of best liquid reagent dilution for pH control?
Greg's Response:
A common misconception is that the slope of the titration curve and, therefore, the system sensitivity can be decreased by reagent dilution. Reagent...
We ask Greg:
What role do you see dynamic simulation playing in the future of best liquid reagent delivery for pH control?
Greg's Response:
If the reagent pipeline is partially filled or empty or a dip tube is backfilled with process fluid, the regent delivery delay becomes the biggest...
We ask Greg:
What role do you see dynamic simulation playing in the future of best reagent selection for pH control?
Greg's Response:
For a reagent dose to be precise enough, the reagent’s logarithmic acid dissociation constant (pKa) should be close to the pH set point so that...
We ask Greg:
What role do you see dynamic simulation playing in the future of best control valve deign for pH control?
Greg's Response:
Stick and slip generally occur together and have a common cause of friction in the actuator design, stem packing, and seating surfaces. Rotary valves...
We ask Greg:
What role do you see dynamic simulation playing in the future of best static mixer use for pH control?
Greg's Response:
Static mixer have noisy pH measurements. Signal filtering can help but a downstream volume is needed to provide smoothing of pH oscillations that...
We ask Greg:
What role do you see dynamic simulation playing in the future of best vessel design for pH control?
Greg's Response:
pH systems are extremely sensitive to the vessel design. A poor design can make good pH control impossible in nearly all systems despite the use of the...
We ask Aaron:
You’ve mentioned the desire to avoid “replacement in kind” and to deliver ROI a couple of times. It’s not intuitive where that return would come from on a DCS replacement project – where is the value? What’s the role for simulation there?
We ask Greg:
What role do you see dynamic simulation playing in the future of best titration curve critical for pH system design?
Greg's Response:
The titration curve is the most important piece of information for designing, commissioning, and troubleshooting pH control systems. Lab titration...
We ask Aaron:
How has dynamic simulation changed the way you approach control system upgrades?
Aaron's Response:
Fundamentally, I think this is a two-way street. The way that simulation has changed the way I approach system modernization projects has shifted almost hand-in-hand with the...
We ask Greg:
What role do you see dynamic simulation playing in the future of best minimization of pH system cost?
Greg's Response:
Because of the pressure to minimize capital costs, a project may sell itself short on the number of stages required. The basic rule from the 1970s was that a...
We ask Aaron:
What is the role of dynamic simulation in control system modernization?
Aaron's Response:
In control system modernization projects – that is, brownfield projects designed to replace and improve the automation systems in plants – the focus is on risk....
We ask Greg:
What role do you see dynamic simulation playing in the future of developing the best maximization of reactor production rate?
Greg's Response:
Production rate can be maximized by a valve position controller (VPC) monitoring coolant valve position. The VPC setpoint is the...
