How to use total dissolved solids measurements to evaluate the performance of diffuser washers-A mill study

Riku Kopra*, Anna Pesonen, Jari Käyhkö, Olli Dahl

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


Various types of pulp washing equipment are available. Each washing device has a unique mechanical construction, and the washing principle is often a combination of dilution, thickening, and displacement washing. In this work, the performance of the pressure diffuser washer is studied.

In stepwise trials, the effect of the feed and discharge consistencies on the performance of the diffuser was studied. The effect of the downward velocity of the screen on the pressure diffuser's washing efficiency was also studied. The measurement of total dissolved solids (TDS) by a process refractometer was used as a wash loss measurement unit and the refractometer's results were used in the calculations of standardized Norden efficiency (E10) values. The chemical oxygen demand (COD) and conductivity values were also measured and their results compared to the TDS results.

The results indicated that feed consistency has a significant effect on the performance and effectiveness of the diffuser washers in the mill. It can also be stated that when the downward velocity of the screen is adjusted to too high a level, the washing efficiency of the pressure diffuser decreases. As a conclusion from the mill tests, it can be stated that even small process parameter changes can provide enhanced diffuser washing at the beginning of the washing line, which has a direct effect on the performance of post-oxygen washing.

Original languageEnglish
Pages (from-to)187-194
Number of pages8
JournalTAPPI Journal
Issue number4
Publication statusPublished - Apr 2020
MoE publication typeA1 Journal article-refereed


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