In Aspen Plus, an electrolyte system is defined as one in which some of the
molecular species dissociate partially or completely into ions in a liquid solvent,
and/or some of the molecular species precipitate as salts. These dissociation and
precipitation reactions occur fast enough that the reactions can be considered to
be at chemical equilibrium. The liquid phase equilibrium reactions that describe
this behavior are referred to as the solution chemistry. In Aspen Plus, solution
chemistry is often referred to simply as Chemistry.
Solution chemistry has a major impact on the simulation of electrolyte systems.
For nonelectrolyte systems, chemical reactions generally occur only in reactors. In
Aspen Plus, all unit operation models can handle electrolyte reactions.
Solution chemistry also impacts physical property calculations and phase
equilibrium calculations. The presence of ions in the liquid phase causes highly
nonideal thermodynamic behavior. Aspen Plus provides specialized
thermodynamic models and built-in data to represent the nonideal behavior of
liquid phase components in order to get accurate results.