Understand reaction submodels for equilibrium reactions

AVEVA Process Simulation offers a rich modelling environment in which you can express reaction models in a mathematical sense. As the open-equation environment does not impose any restrictions on the modeller, you can enter many kinds of equations and are not restricted to a pre-defined set of reaction formulations. This allows you to enter reaction formulations based on the equilibrium reaction data that you have available. However, you may want to modify the typical formulations for expressing the reaction equilibrium to a dimensionless form based on the numerical properties of the system that you want to model and the way the equation solver solves the equations. This provides better performance for your equilibrium reaction submodels in AVEVA Process Simulation.

In AVEVA Process Simulation, we have written the default equilibrium reaction submodels in a dimensionless form. Whereas reactions described by kinetic laws (for example, the power law or Langmuir-Hinshelwood) express the amount of converted material as extensive flows (either in kmol/s, kmol/(s·kg-cat), or kmol/(s·m³)), we represent the change in moles of an equilibrium reaction by the dz variable (kmol/(kmol-feed)). You can interpret the dz variable as the difference in overall molar composition between the pre-reaction and post-reaction states for each component in the mixture.