2. Module-oriented and equation-oriented simulators

The fundamental aspect of process simulation is the identification of the elementary components whose assembly enables the process model to be built. At the conceptual level, and as a direct consequence at the numerical level, there are two opposing approaches: the "module-oriented" (MO) approach and the "equation-oriented" (EO) approach.

• The OM approach has been adopted by the majority of commercial simulators. The most widely used are: Aspen Plusä, Chemcadä, Aspen HYSYSä, Pro/IIä and ProSimPlusä.

  In the OM approach, the basic element for building the process model is the unit operation model known as a "module". This approach corresponds to the classical and natural vision of the process, which results from the arrangement of unit operations dedicated to a precise function such as reaction or separation. The user...