A. Ahlstrom Corporation

Ahlstrom Machinery Oy

Ahlstromforetagen Svenska Ab

Krister Sannholm

Erik Agren

Olof Fagerlind

Ake Schonberg

Juhani Hoikkala

Falling film evaporator

To decrease the sulfur emissions of a sulfate pulp mill, and achieve other advantages, black liquor is heated at a temperature higher than the cooking temperature of the sulfate cook (e.g. between 190.degree. C.-350.degree. C.) and the sulfidity of white liquor produced from the black liquor is adjusted by adjusting the temperature and/or retention time of the heat treatment so that a predetermined amount of sulfur compounds are separated from the black liquor. Pressure heat treatment may occur prior to or after evaporation of the black liquor, or between evaporation stages. Preferably, the sulfur containing gas is thereafter divided into different fractions which are separately cornbusted.

Method of controlling sulfidity of a sulfate pulp mill

To decrease the sulfur emissions of a sulfate cellulose mill, black liquor is heated before the last effect of the evaporation at a temperature higher than the cooking temperature of the sulfate cook and the sulfidity of white liquor is adjusted by adjusting the temperature and/or retention time of the heat treatment so that a predetermined amount of sulfur compounds are separated from the gaseous black liquor. Preferably, the sulfur containing gas is thereafter divided into different fractions and separately combusted.

Method of controlling sulfidity of a sulfate cellulose mill

A method of dehumidifying gas in which gas is brought into direct contact with an absorption liquid in one or more stages, and in which the absorption liquid in at least one stage comprises a salt solution which includes an amount of salt crystals so that the concentration of the salt solution will not be substantially reduced in the absorption stage.

Method of dehumidifying gases

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Espoo, Finland

Krister Sannholm