Sodium and sulfur balance of a kraft pulp mill

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School of Chemical Engineering | Master's thesis
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Date

2010

Major/Subject

Selluloosatekniikka

Mcode

Puu-23

Degree programme

Language

en

Pages

90 s. + liitt. 50

Series

Abstract

The aim of this study was to create sodium and sulfur balances of the UPM-Kymmene Kaukas kraft pulp mill. Mill had experienced difficulties in sulfidity control and information was needed on if the process is still running in desired manner or if there is unknown or increased outflow for sodium and sulfur. In addition to this, there was interest in having a program that could help in sulfidity and process alkali amount control strategy planning. For the balances and for creating the program, samples were taken from the incoming and outgoing flows of the chemical cycle for elemental analysis. Also, all major internal flows were analyzed. Samples were sent for analyses to VTT laboratories in Espoo. Flow information was gathered from the process information system. Some values were calculated from the average values of 2008 with correction to right production level. It was noted that the balances corresponded to the literature values, the biggest outflows were brown stock to bleaching on both fiber lines. The brown stock washer of the mill have higher efficiency than those of an average mill, therefore the cause of the sulfidity control problem can be the decreased washing efficiency of these washers. Simulation program was obtained to work in desired manner and the prediction of the development of sulfidity and process alkali amount worked well during the mill trial.

Description

Supervisor

Sixta, Herbert

Thesis advisor

Tidenberg, Timo

Keywords

chemical balance, kemikaalitase, chemical cycle, kemikaalikierto, simulation, simulaatio

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