Office paper bulk optimization in a paper machine using
multivariate techniques

Authors*: Gabriel Duarte Almeida Sousa1
Cidália T. Abreu2
José L. Amaral3
Carlos Brás4

Keywords: Bulk, multivariate, optimization, paper machine

Abstract
This work aimed at identifying the primary causes of paper bulk
variations at an industrial paper machine by multivariate process
data analysis and experimental design techniques as a tool to define
production strategies that minimize bulk’s variations and/or maximize
bulk’s objective.
Process data for two different paper products of a paper mill were
collected, corresponding to a two-year period. These data were used
as input for a multivariate analysis, including PCA and PCR using
paper bulk as a dependent variable. PCR models of paper bulk
identified the most significant variables affecting it: pulp beatability,
refining strategy, shoe-press operating conditions and some furnish
properties. The interpretation of the main principal components
suggests that paper bulk variations are most probably caused by
the misalignment of refining operating conditions in the presence
of pulp quality variations, which are compensated by shoe-press
variables in order to assure paper machine runnability. Based upon
the multivariate analysis conclusions, a preliminary laboratorial
experimental design was performed involving the controlled
variation, at three levels, of industrial pulp specific refining energy
and pressure of a lab press. ANOVA analysis of these results revealed
that bulk depends on the quadratic effect of press pressure.

Authors’ references:
1. RAIZ, Research Institute of Forestry and Paper, Quinta de S. Francisco, Apart. 15, 3801-501 Eixo, Portugal.
phone: +351 234 920 146, fax: +351 234 931 359 – E-mail: gabriel.sousa@portucelsoporcel.com
2. Portucel, Setúbal Paper Mill, Complexo Industrial de Setúbal, Apart. 55, 2901-861 Setúbal, Portugal – E-mail: cidalia.torre@portucelsoporcel.com
3. RAIZ, Research Institute of Forestry & Paper, Quinta de S. Francisco, Apart. 15, 3801-501 Eixo, Portugal – E-mail: jose.luis.amaral@portucelsoporcel.com
4. Portucel, Setúbal Paper Mill, Complexo Industrial de Setúbal, Apart. 55, 2901-861 Setúbal, Portugal – E-mail: carlos.bras@portucelsoporcel.com
Corresponding author: Gabriel Duarte Almeida Sousa – E-mail: gabriel.sousa@portucelsoporcel.com

O PAPEL vol. 72, num. 8, pp. 50 - 55 AUG 2011