Prof. Dr.-Ing. Dr. h.c. mult. E.D. Gilles
Institut für Systemdynamik und Regelungstechnik (ISR)
Universität Stuttgart

Pfaffenwaldring 9, 70550 Stuttgart, Germany
Fax: +49 (0)711 685-6371
E-mail: secretary@isr.uni-stuttgart.de

DIVA

A Tool for Dynamic Simulation of Chemical Engineering Applications

The dynamic simulation environment for chemical engineering plants DIVA is mainly being developed at the Institut für Systemdynamik und Regelungstechnik (ISR) at the University of Stuttgart, Germany, under the guidance of Prof. Gilles. DIVA is used in cooperative research projects with partners from universities and industry.
DIVA contains a model library of generic process unit models. Examples of pre-defined process unit models are: distillation columns, condensers, reboilers, CSTRs, tubular reactors, valves, pumps, etc.
A user of DIVA selects individual process unit models from the model library and aggregates these to plant models by specifying plant flow sheets.
The DIVA plant models and process unit models are represented in form of linear-implicit differential-algebraic equations (DAE) with a differential index of one:
For the implementation of DIVA process unit models, in the model library a code generator can be used. The model equations are written in a symbolic code generator input file. The code generator translates these equations to FORTRAN subroutines that represent the process unit models in the DIVA model library [10].
To support the modeler a knowledge-based process modelling tool (ProMot) is being developed. ProMot is supposed to interacitvely support the modular development of unit model by aggregation elementary modeling entities that are stored in an object-oriented knowledge base [11].
For all numerical methods in DIVA a simultaneous solution strategy and sparse matrix techniques are used. In particular DIVA provides the following numerical algorithms:
- For the integration of the DAE:
  - Backward-differentiation-method (sDASSL, [1])
  - Extrapolation method (LIMEXs, [2])
  - Runge-Kutta-method (Radau5s, [3], sDIRK4)
- Solving of systems of nonlinear equations for the calculation of consistent initial conditions and the calculation of steady state solutions:
  - Levenberg-algorithm (Harwell NS13)
  - Newton-method (NLEQ1s [9])
- Event handling routines that account for discontinuites and discrete events in the model equations.
- A continuation algorithm with local parametrization and stepsize control including methods for stability and bifurcation analysis [5].
- Algorithms for dynamic optimization problems, like sensitivity analysis, parameter identification, experimental design and trajectory optimization, are currently under development. [7]
Due to the sparse matrix techniques used for the numerical methods, DIVA is suitable for large scale systems with as much as 10.000 state-variables with 100.000 jacobian entries which have been realized with reasonable computation times.
The simulator DIVA is connected in several aspects with MATLAB 4.2, a commercial software for matrix based system analysis and synthesis. MATLAB is used for the visualization of simulation results (DIVA-Graphik) and for control engineering analysis and design methods.
As examples for the simulation results obtainable using the DIVA-Graphik in MATLAB a 3-D plot of the transient behaviour of a distillation column and a 2-D plot of the column profile at the final time are shown:
Some examples of chemical engineering processes that have been simulated with DIVA are:
- Styrene production plant
- Butylacetate production plant
- (Reactive) Distillation Processes [8]
- Novel Reactor concepts (Circulation Loop Reactor) for air pollution reduction [6]
- Simulated-Moving-Bed Chromatography
- Liquid Chromatography
- Multiphase Reaction Processes
- Liquid-Liquid-Extraction [12]
- Cristallization
The simulator DIVA is running on the following hardware platforms:
- VAX/AXP under Open VMS
- SUN under Solaris 2.x
- PC under OS/2 and Linux
The simulator DIVA contains about 900 FORTRAN-routines and is being developed using CASE-tools.
For more information about DIVA refer to [4] (in German).

References

Klaus-Dieter Mohl
Fri Mar 14 15:16:59 MET 1997