Sodium salt scaling in black liquor evaporators and the effects of the addition of tall oil brine
Journal article, 2021

Sodium salt scaling, i. e. the formation of doubles salts comprised of sodium, carbonate and sulphate on the heat transfer surfaces, is a common problem that occurs during black liquor evaporation. In this study, experimental results are presented that provide new insights into the formation and composition of such scales and how they are influenced by the addition of tall oil brine. It was found that increased content of sodium carbonate and sodium sulphate in the black liquor increased scaling, while the ratio between carbonate and sulphate had a lesser influence than reported in other studies. Black liquor created loose clay-like scales comprised of aggregated crystals and black liquor, whereas salt solutions created hard mineral-like scales. The scales formed by both the black liquor and the salt solution showed a tendency to fall off during formation after primary nucleation. It was also found that both tall oil soap and alkalized tall oil brine could inhibit the formation of scales. The inhibition effect is stronger if adding the soap or brine just before scaling starts, but also depends on the amount added, the sodium carbonate and sodium sulphate content in the liquor as well as other factors.

Sodium sulphate

Sodium carbonate

Scaling

Black liquor evaporation

Tall oil brine

Author

Erik Karlsson

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Forest Products and Chemical Engineering

RISE Research Institutes of Sweden

Anders Åkesjö

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Forest Products and Chemical Engineering

Nordic Pulp and Paper Research Journal

0283-2631 (ISSN)

Vol. 36 1 1-20

Strategies to minimize fouling in black liquor evaporators

Stora Enso AB, 2016-10-01 -- 2020-04-30.

Södra, 2016-10-01 -- 2020-04-30.

Swedish Energy Agency, 2016-10-01 -- 2020-04-30.

Valmet , 2016-10-01 -- 2020-04-30.

Subject Categories

Tribology

Bio Materials

Chemical Process Engineering

DOI

10.1515/npprj-2020-0081

More information

Latest update

5/19/2021