Optimizing Simulation of Refinery and Petrochemical Reactors with Molecular Structure Fluid Lumping and Object Oriented Unit Design

The modeling of reactors is the most challenging and least supported aspect of process simulation. In many cases, the reactor is the heart of the process and without a good model of the reactor, the value of the simulation model is highly discounted. Simulation software typically contains only very basic reactor models and these models do not provide adequate capabilities to predict hydraulics, heat and mass transfer, complex reaction networks and catalyst effects to the degree necessary to answer important process questions. One way to keep up with these demands has come in the form of developing generic ways of modeling wide ranges of problems in object oriented structures.  This allows for smaller scoped engineering problems to be created and validated for use in a bigger overall problem.  The VMG PIONA characterization, a molecular structure fluid lumping methodology, is an example of these developments where molecular structure modeling is used to not only match mixture properties, but to also define an automatic kinetic reaction pathway grid for the shifting of molecular species.  Reactive or non-reactive unit operations built with similar object oriented pieces, complemented by this generic thermodynamic foundation, are then developed with a much faster turnaround rate.  Examples of reactive unit operations in this molecular structure environment that will be reviewed include cracking furnaces, fuel cells, urea strippers, and Fischer-Tropsch reactor units.  Each of these will be broken down into a collection of developed objects meant to handle pressure drop, energy and material balances, and reactive influences within the system.