Abstract
In the work an algorithm for process optimization using flowsheet
simulation has been developed.The algorithm is designed for use in procedure
oriented simulation environment and it can be easily adapted to existing
flowsheeting programs.The algorithm is based on a successive quadratic
programming algorithm by Powell.Some enhancements have been added to the
Powell algorithm to make it less sensitive to the scaling of the variables and
the objective.The main emphasis in the work has been on the development of
schemes for numerical evaluation of gradients required be the Powell
algorithm.During the numerical testing of the algorithm development it was
noted that the noise generated by the iterative unit procedures can,
especially in large processes, seriously affect the accuracy of the
derivatives calculated, if the perturbation factors are not properly selected.
The problem was solved by developing an algorithm that can automatically
select suitable perturbation factors for the iteration variables.The algorithm
is based on the balancing of noiseinduced and truncation errors.A novel
forward difference algorithm has also been developed where the effect of
truncation error has been reduced by introducing correction factors, based on
approximated second derivatives.The correction factors, which are reevaluated
periodically, are calculated using the general difference formula.The
optimization algorithm has been tested using realistic example problems.The
performance of the algorithm has been adequate.In most cases the number of
simulation time equivalents required to reach the optimum has been no more
than ten.
Original language  English 

Qualification  Doctor Degree 
Awarding Institution 

Supervisors/Advisors 

Place of Publication  Espoo 
Publisher  
Print ISBNs  9513821366 
Publication status  Published  1984 
MoE publication type  G4 Doctoral dissertation (monograph) 
Keywords
 optimization
 simulation
 process charting
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Cite this
Kaijaluoto, S. (1984). Process optimization by flowsheet simulation: Dissertation. VTT Technical Research Centre of Finland.