Tips & Tricks - Copying Reactions in VMGSim 7.0
Simulation of a reactor often requires the use of a number of different models as new information becomes available. Transitioning between reactor models is easier than ever with VMGSim 7.0, which allows users to copy reactions with the click of a button. The ability to copy reactions eliminates the long, tedious process of entering reaction data for each model- a task that is also error prone. Users can take advantage of this helpful new feature to create multiple reactor models faster. In this article, you will find out how this is possible as we follow the evolution of a simple reactor design model.
In the early stages of process design, a conversion reactor is an attractive modeling tool because an initial estimate of plant behaviour can be acquired from stoichiometric and conversion data alone. Figure 1 shows how a conversion reactor might be set up for the example process. Clicking on Add/Edit… in the Reactions tab allows the user to enter basic data for each reaction. After specifying the feed, adiabatic conditions, and a pressure drop, the reactor is able to solve for the product stream conditions.
Figure 1: Specifying reaction data in a conversion reactor
In the next modeling stage it is valuable to study the behavior of an equilibrium model because it applies restrictions of thermodynamic equilibrium to the process. A conversion model can transition to an equilibrium model when equilibrium data is available. Reactions from the conversion reactor can be copied to the new equilibrium reactor by clicking Copy From… in the equilibrium reactor’s Reactions tab. As shown in Figure 2, the user has a choice between copying a specific reaction or all reactions from a particular reactor.
Figure 2: Copying reaction data from a conversion reactor to an equilibrium reactor
After clicking OK, all relevant reaction data is copied to the new (Equilibrium) reactor (see Figure 3). Note that the conversion specs in the first reactor are not available in the equilibrium reactor, as they are not relevant in this model.
Figure 3: Reaction data in equilibrium reactor, as copied from conversion reactor
The new model is solved after the equilibrium constant of each reaction is specified (see Figure 4). The feasibility and design of the process may then be re-evaluated using these more accurate results.
Figure 4: Solved equilibrium model
Once kinetic data is available, process behaviour is most accurately simulated using a kinetic model. In this case, a CSTR model is selected. As with the equilibrium reactor, reaction data is copied to the CSTR from one of the existing reactors (Figure 5). Once again, all relevant data is automatically copied.
Figure 5: CSTR reaction data, as copied from the equilibrium reactor
Then, the user only has to specify kinetic data for the reactions in order to solve the model, as in Figure 6.
Figure 6: Solved CSTR model
The same process could be followed in order to copy reactions from this CSTR to a new PFR model. In that case all kinetic data would be automatically copied along with stoichiometric data, since it is relevant to both models.
As demonstrated, VMGSim 7.0 facilitates efficient and accurate transitions between reactor models. Reaction data can be copied between conversion, equilibrium, CSTR, and PFR models. The effortless transfer of reaction data guarantees a better user experience whether your goal is reactor design evolution, model regression, or in-depth process analysis.
Please contact your local VMG office for more information.