ROBUST DYNAMIC SIMULATION OF CHEMICAL-ENGINEERING PROCESSES

Modelling of chemical engineering processes operating under transient conditions often gives rise to mixed systems of differential and algebraic equations (DAEs). There are currently reliable and efficient numerical methods for the solution of DAEs provided that the simulation does not depart too far from a region of 'normal' operation. Outside this region, existing methods for the solution of the DAEs may become inefficient, or even fail. This paper examines the changes that must be made to allow a DAE solver to overcome some of these difficulties. Particular problems that are considered are the problems of imposing physical bounds on the numerical solution, integrating partially determined systems and solving systems containing fast transients.