Parameter estimation of a pulp digester model with derivative-free optimization strategies

João C Seiça,Florbela P Fernandes,Lino O Santos,Natércia C P Fernandes,Andrey Romanenko

doi:10.1063/1.4992428

Abstract

The work concerns the parameter estimation in the context of the mechanistic modelling of a pulp digester. The problem is cast as a box bounded nonlinear global optimization problem in order to minimize the mismatch between the model outputs with the experimental data observed at a real pulp and paper plant. MCSFilter and Simulated Annealing global optimization methods were used to solve the optimization problem. While the former took longer to converge to the global minimum, the latter terminated faster at a significantly higher value of the objective function and, thus, failed to find the global solution.The work concerns the parameter estimation in the context of the mechanistic modelling of a pulp digester. The problem is cast as a box bounded nonlinear global optimization problem in order to minimize the mismatch between the model outputs with the experimental data observed at a real pulp and paper plant. MCSFilter and Simulated Annealing global optimization methods were used to solve the optimization problem. While the former took longer to converge to the global minimum, the latter terminated faster at a significantly higher value of the objective function and, thus, failed to find the global solution.

Highlights

Pulp and paper industry plays an important role in world economy
The weighting factors in the cost function (1a) assigned to each output variable are given in Table 2 and were chosen taking into account the relative importance of each of the output variables
The initial guess for the model parameters coincide with the same initial guess of the previous study of Fernandes [3]

Summary

Introduction

Pulp and paper industry plays an important role in world economy. The pulp production line is quite complex as it involves thousands of variables that have to be monitored and controlled. Its very sui generis design and physical/chemical characteristics of the process require sophisticated control strategies in order to ensure safe and economically viable operation. Since these strategies rely on mathematical models that predict the unit behaviour, their accuracy determine the steady-state and dynamic performance of the closed-loop system. The digester, represented schematically, presents a set of peculiarities that make its modelling a quite challenging task [2, 3]. It is a heterogeneous moving bed reactor that operates in continuous mode and where

Objectives

Results

Conclusion