Simulationunique numerical

algorithms

on-line information

direct interaction

open data formats

off-line capabilities

PDE's for spatial

profiles

3D-visualization of

time dependent

spatial problems

PRESTO is a sophisticated tool for the modeling of any kind of kinetic reactions.High-end mathematical techniques are combined with a state-of-the-art user-interface. Within this framework the definition of reactors s, coefficient or speciesis completely to the user. All data may be plotted to graphical outputopenwindows during simulation. The output be updated after each individualcanintegration time-step. Furthermore, during simulation information about thetheactual chemical and numerical problem status is provided. The full simulation orselected parts of itcan be recorded for later examination.

The ASCII format for in- and output files facilitates editing anyof information bysoftware of your convenience.

A sophisticated parameter estimator helps deriving the rate coefficients fromexperimental data. Standard algorithms, stochastic algorithms, andbox search procedures incombination with contourplots provide a detailedproblem analysis.

Experimental data can bevisualized together withthe simulation.

extensive numericalinformation

Spatial problems can be formulated using partialdifferential equations (PDE) considering diffusion,convection and spatial differentiated reactionrates. The highly efficient solver cares forautomatic, self-adaptive and non-equidistantdiscretization with respect to the spatialcoordinate and integration time axis. Thus thecomputational efforts are reduced to a minimum.

Results are showneither as the fullprofiles at each timestep as1, time slices ata certain spatialcoordinate2, timedependent integratedvalue of each profile ,3

or time dependentasevolution ofgraphsspatial speciesprofiles4.

Example:

Polymer production andspatial equilibration afterpoint-wise initiator feed.

(1)(2)

(3)

(4)

(4)

Declare components using names of your ownchoice and define their thermodynamic properties.

Implement your reaction systemfollowing intuitive steps.

Define a module with 3 clicks!

Interfaceeasy-to-use GUI

flat dialog

structure

intuitive

efficient

Reactors: An arbitrary number of reactors can be defined, each having individual characteristicssuch as: temperature(-profiles), pressure, volume, heat-balance, operation mode (batch,feed-batch, continuous flow, CSTR or tubular). A powerful phase concept enables thetreatment of multiple phases for .heterogeneous reactions

Coefficients: Rate coefficients and constants within a model may be defined as being temperatureand pressure dependent following an Arrhenius term.

Reactants: Species and species profiles defined considering their thermodynamicare byspatialproperties, initial values of concentration and profiles or feed-strategies.

Reaction steps: Most of the reaction systems may be built up using the general kinetic step shownabove. It provides any order of reaction with respect to the reactants or the directimplementation of the reaction rate. The stoichiometry may be defined totally free aswell as the overall rate. Furthermore, there exists a large variety of modules especiallydesigned for certain application fields. These include bio-kinetics, diffusion, convection,mass-transfer and several types of partial differential equations.

The creation of a model is supported by the comfortable Workshop. This Workshop is shared by all CiTtools to unify model implementation and to switch easily in-between the CiT tools without extendedphases of individual training.

Any component that is necessaryto picture a process can bedefined by templates. An appro-priate set of resources from the

Windows GUI (graphical user interface) expects the user's input. It is demonstrated here for thedefinition of a general reaction step.

The definition of recipes allows anefficient control of the reactor operationstrategy. The concept of tank recipescorresponds to strategies of batch andfeed-batch operation as well as ofcontinuous flow. Within each tank evenspecies mixtures can be defined. For thesefeeds it is possible to import mass versustime profiles directly as ASCII data fromyour balance. When modeling processesthat require multiple reactors, for eachreactor an individual recipe can bedefined.

The reactor module accounts forcontinuous and discontinuousdischarges from the reactor.Complete sampling programs can besimulated using this module.The volume control can be setmanually or automatically; full massbalances are calculated in any case.

Special file formats for files containing experimentaldata allow recipe control by measured data sets.

Controlrecipe concept

batch, feed-batch,

CSTR, tubular,

complex operation

modes

tracing experimental

data

Other special features are:

- By combining measured data files with recipes complex reactor operation programsare simulated that account for temperature and feed programs.

- Using this feature in combination with the parameter estimation tools, multiple ratecoefficients can be estimated from whole sets of experimental data referring todynamic reactor operation strategies simultaneously.

- Individual scaling or weight factors as well as penalty functions can be defined toaccount for differing precision of experimental data.

Data Editingfast manipulation

merging of different

data sets

quick display

As an extra feature, acustomized editor for thehandling of measured data filesis available. It simplifies editingdata and key words consideringall features of the parameterestimation tool. This tool is alsocapable of mergingexperimental data resultingfrom measurements ondifferent time bases.

A graphical displayis included for quickdata inspection.This is useful fortesting estimationprocedures by in- orexcluding groups ofmeasured data.

The reactor control ofmeasured data is superiorto the definition of recipes.

AdvancedFeatures

bio-kinetics

heat transferthermodynamics

multiple phase

concept

internal script

language

library

A flexible reactor concept providesstand-alone reactors or cascades. Foreach reactor the heat-balance andmultiple phases can be defined. Specialmodules allow the species exchange in-between the phases.

A b - sio kinetic pattern1 assist inmodeling this significant class ofprocesses.

Partial differential equations3 (PDE-modules) facilitate the implementationof spatial profiles, particle distributionsor reactions in heterogeneous reactionmixtures.

Using the integrated functioninterpreter (no external compilation)arbitrary functionalities may beimplemented for heat-balance , phase-4

exchange, particle-formation,-agglomeration or -degradation.

For special demands ordinarydifferential equations (ODE -modules) 2

provide direct access and control e.g. tospecies, species distributions or balancevariables.

There are several options to control feedand exit streams directly, using the:recipe or by ODEs.module

The library in combination with the function interpreter enables the calculation of self-defined quantitiesor implementation of control concepts, generating individual on-line output.

The syntax is intuitive and comparable to usualprogramming languages. Procedures may be usedfor structural implementation avoidingunnecessary and error-prone redoubling of code.

This is ideal for adopting a model to sensors thatare measured experimentally, e.g. in the casethese are not related directly to single species.

(1)

(2)

(3)

(4)

ParameterEstimation

rate parameter

Arrhenius

estimation

model parameter

statistical

information

no sheet or data

limitations

value scaling

value weigh ingt

free penalty

functions

Rate coefficients and anyother model parameterscan be fitted by theparameter estimationtool. As sensors anyspecies and systemvariable may act. Alsoquantities that aredefined by the user viathe function interpretercan be used.

An unlimited number ofdata sheets can beprocessed, eachcorresponding to anindividual experimenthaving its own recipe,operation mode,temperature and feedprofile.

Quick sensitivity tests canbe performed withoutchanging the generalsetup of the estimationarrangement via activatingor deactivating individualconstants or data sheets.

The configurationsummarizeses the datacollection, model and ratecoefficients as well asscaling and weightingpreferences together withpenalty functions.

Sophisticated statistical information isdisplayed on-line during the fittingprocedure. Results providing criteria for thegoodness of fit, correlation of parametersand individual sensitivity are available.

There are no principle limitations withrespect to the number of data sheets orparameters to be estimated.

Concerning rate coefficients, either theirabsolute values may be fitted and evaluatedas Arrhenius term further on, or theArrhenius parameters may be estimateddirectly. During estimation limiting boundsmay be set.

ASCII log-files provide a history of the fittingprocedure for later inspection of the efficiencyof the estimation process. All statisticalinformation together with the course ofparameter estimates are collected. Evendetailed information about individualcontributions of single compounts to theresidual within each experiment is available.

The box-search is the idealtool for taking a first glanceat a fitting problem andgetting an idea aboutparameter sensitivities orcorrelations, leading toefficient initial values.

For the fitting of more thantwo parameters, thesensitivity of any of theircombinations may beinspected using the internalcontour plot function.

ASCII output files enable theprocessing and thevisualization of data usingother programs.

In order to avoid laborious screening, a simulatedannealing algorithm is implemented for a statisticalsearch. The combination of gradient and randomwalk techniques assures finding identical solutionsfrom varying initial conditions while concentratingcomputational efforts on the sensitivity area ofinterest.

The data are logged into ASCII files for laterinspection and graphical representation by othersophisticated programs.

k1

k2

residual

residual

k1

k3

The integrated 3D OpenGL visualization helps to inspectsensitivity matrices and correlations of estimated parametersefficiently. The surface may be zoomed, shifted and rotated byany axis. It may be displayed as colored or shaded surface aswell as transparent grid.

This feature is also available asstand-alone tool for thevisualization of matrices.

ParameterEstimation

box-search

simulated

annealing

3D-visualization

Connectibilityopen data formats

for import / export

batch automation

OLE capability

Web-functionality

The OLE automationserver enables widescreening of experimentalconditions and sensitivitystudies, controlled e.g. byVisual Basic or anyalternative OLE client.Large data quantities maybe processed followingautomated schemes.

HTML functionalitiessimplify documentation.The ouput files in HTML-format include the modeldescription, an archivethat may be run directlywith PRESTO andsimulation results. Thesefiles can be used as astand-alonedocumentation or asinput files for other textprocessors. Furthermore,they can be published onthe inter- or intranet.

k4

k5

PRESTO is not only a very efficient tool for kineticsystems described by ordinary and algebraicdifferential equations, but includes a leading solverfor systems of partial-differential equations.

Numerous modules for a general description ofconvection, transport, diffusion, dispersion,boundary conditions, agglomeration and arbitrarykinetic reactions allow an easy transfer of kineticschemes to distributed variables (e.g. axial or radialco-ordinates in a non-stationary tubular reactor,mixing problems, general PDE's). Parameter andcoefficients of these processes can be formulated asspatial dependent.The Galerkin h-p-algorithm works full self-adaptively, all discretizations are error-controlled. Inconnection with a parameter estimation procedure,the algorithm is even more efficient. The drawbacks

of other solvers (poor error control, missing adaptivity, large number of approximating variables,restriction to local operators, method-of-lines approach), are avoided and overcome in PRESTO. A seriesof challenging problems could be solved with this tool in a unique way. Even free boundary problems(e.g. single particle models) can easily be solved in PRESTO usingthese powerful features. The handling of large PDE systems is assimple as for standard kinetics.

PartialDifferentialEquations

spatial gradients

species profiles

dynamic

computation

By this, in the same manner as forstandard models complex simulationmodels may be defined by linkingelementary basic objects. Recycleoperators provide the facility tomodel loop reactors in an intuitiveway. For results of thepolymerization model shown heresee page 2.

The profile species may bedisplayed as timedependent integral, timeslices at a certaincoordinate using theoutput functions of thelibrary or as full timedependent 3D profilesusing OpenGL techniques(see also page 2).

The example graphs showthe behavior of a tracerpulse within a loopreactor where thebackmixing characteristicis modeled by diffusionand convection operators.

ExtendedProjectManagement

multiple projects

for a single model

quick process

change

direct access to

measured data

PRESTO is available in a secondversion (PRESTO-Kinetics II), thatsupports extended projectmanagement and shares theoutstanding mathematicaltechniques.

It is developed to accompany multi-purpose plants. Plant specific datasuch as reactor configuration andspecified substances are storedsuperior to individual projecttasks.

The project tasks contain processspecific items such as the kineticmodel, rate coefficients, recipesand parameter estimationconfiguration.

Any of the project tasks has access to a commondatabase of experimental data for comparison andparameter estimation.

By changing tasks models may be tested veryefficiently without changing the gobal project. Anydevelopment of model or process adaption issummarized within the same gobal project to keepthings together.

Moreover, an interface is available to link species todatabases for calculation of thermodynamicproperties such as activity coefficients.

Behind this advanced interface for multipleproject management there exist the same user-friendly dialogues as in PRESTO-Kinetics.

Therefore there is no need for retraining whenswitching to PRESTO-Kinetics II and back.

Project tasks are fully compatible with modelsof PRESTO-Kinetics II and vice versa.

Data Hologramfree label and

group definition

object oriented

data classification

application

bounded links

for files

graphical

representation of

data

Initial situation:

Unstructured collectionconsisting of individualdata files withinhomogeneouscontent ...

... collect labels anddata ranges togroups of your ownchoice and parsethem hierarchicallyto find the data setsof your interest ...

multi-dimensional overview of extended file collections for experimental data

hierarchical structurization follows flexible differing aspects of interest

labels for structurization are based on the individual files content

user-defined labels that describe numerical data, abstract meanings, ranges of subjects

user defined filters

summarizing labels or numerical data in self-defined groups

(easy) automatic scanning of labels

Organization using the hologram:

User defined labels in arbitrary orderdescribe the content of the data fileand build the basic structure thathas to be followed ...

Dr. Michael Wulkow Computing in Technology GmbHOldenburger Straße 200D - 26180 Rastede

Germany

Tel.: +49 (0) 44 02 / 84 2 48Fax: +49 (0) 44 02 / 939 927mwulkow-cit@t-online.dehttp://www.wst.shuttle.de/cit/

References

Further Tools

The products of CiT are used world-wide in academia and industry.

On your request it will be a pleasure for us providing a comprehensive list of reference customers and

projects.

Version 3.03.06

Potential applications of PRESTO range from simulating general kinetic schemes up to treating

2-dimensional problems or bio-kinetics. And there are more products of CiT that share all the same

outstanding numerical technology:

Predici: rigorous treatment of complete molecular weight distributions in arbitrarypolymerization processes

reaction step patterns for propagation, termination, transfer (monomer, agent,polymer), depolymerization and polymer degradation, description of oligomers, chain-length dependent reactions

copolymerization with any number of monomer species

treatment of composition and branching distributions

particle size distributions in heterogeneous systems

parameter estimation (multiple experiments)

temperature- and pressure profiles as well as recipes for reactors or cascades of reactors

manipulation of kinetic rate coefficients and reactants by use of an interpreter mechanism

analysis of polymer properties

input of measured concentrations as well as molecular weight distributions

Parsival: rigorous treatment of particle size distributions in heterogeneous process units (e.g.crystallization)

reaction step patterns for particle growth, nucleation, agglomeration, breakage, fine'sdissolution, convection, diffusion, boundary conditions, kinetic reactions

flow sheets with classified flow and exit

parameter estimation

Rioval: management tool for water quality modeling in streams

interface for the description of rivers and input from treatment plants

simulation based on a comprehensive and well-tested biofilm model