Abstract
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) 
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Keywords
 optimization
 simulation
 process charting
Cite this
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Process optimization by flowsheet simulation : Dissertation. / Kaijaluoto, Sakari.
Espoo : VTT Technical Research Centre of Finland, 1984. 101 p.Research output: Thesis › Dissertation › Monograph
TY  THES
T1  Process optimization by flowsheet simulation
T2  Dissertation
AU  Kaijaluoto, Sakari
PY  1984
Y1  1984
N2  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.
AB  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.
KW  optimization
KW  simulation
KW  process charting
M3  Dissertation
SN  9513821366
T3  Publications / Technical Research Centre of Finland
PB  VTT Technical Research Centre of Finland
CY  Espoo
ER 