Feedback from our users is what inspires us to keep making CHEMCAD better. Many features, like this one, were added to the software as a direct response to user need. That’s why we consider every CHEMCAD user part of our development team.

Sequential-modular simulations converge by assuming a single direction of flow, which for most processes is correct by design. However, in extra-ordinary circumstances, say in emergency conditions, a rise in pressure in one area can cause flow to reverse. And of course, some batch and semi-batch processes are designed to allow "reverse" flow in some areas.

Several years ago, we added simultaneous-modular convergence routines which do not restrict a simulation to a single direction of flow and a hydraulic balancing routine that calculates flow and pressure throughout a flowsheet. Many of our users immediately began doing small- and large-scale simulations on piping networks, semi-batch plants, and emergency relief scenarios.

Some customers further requested that we add more detailed relief devices for use in these simulations. Although our CSTR and VESSEL unit operations already had detailed, built-in relief device calculations, there was a need for a new unit operation to be placed anywhere on the flowsheet.

In response, we developed the new relief device unit operation, which is fully integrated into the simultaneous modular calculations. As such, in a dynamic simulation, it will open when the relieving pressure is reached, and the model will calculate the resulting change over time in pressure and flow throughout the system.

This model is now available in CC-DYNAMICS and CC-SAFETY NET. If you'd like to learn more, please contact us.

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