Understanding the dynamic behavior of Kamyr digesters

摘要

This paper presents process sensitivity and interaction analysis for Kamyr digesters, used for theproduction of paper pulp from wood chips, using the Purdue dynamic model. In sensitivity analysis,responses of blow line Kappa number to step changes in 17 scaled input variables were investigated.The responses to the five most significant inputs, i.e., white liquor caustic concentration and flow rate,upper and lower heater outlet temperatures and extraction flow rate, were approximated, with goodaccuracy, by First Order Plus Time Delay transfer functions using SigmaPlot Interaction analysis hasbeen carried out using Relative Gain Array, Singular Value Decomposition and a condition-numberscaling technique to improve the ill-conditioned system. For the purpose of pairing in multivariablecontrol, and using a 4× 4 gain matrix, it has been shown that blow-line Kappa number is to bepaired with lower heater outlet temperature, extraction caustic concentration with white liquor flowrate, extraction temperature with upper heater outlet temperature, and solids fraction in theextraction stream with white liquor caustic concentration.