Process for decreasing the tendency to form deposits in plants for evaporating spent sulfite liquors

US4941946A · kind A · utility

Assignee

• Metallgesellschaft AG · DE

Inventors

• Manfred Henn · Heidelberg, DE
• Klaus Begerow · Straelen, DE
• Volker Wichert · Voerde, DE

Key dates

• Filing date: Feb 6, 1989
• Grant date: Jul 17, 1990
• Expiry date: Feb 6, 2009

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S210/928
• WIPO field: Textile and paper machines
• WIPO sector: Mechanical engineering

Abstract

A process for decreasing the tendency to form deposits in plants for evaporating spent sulfite liquors used to produce woodpulp. In the process, the liquors are treated with polyacrylic acids having a low molecular weight. In order to prevent virtually any deposition and to increase the evaporation rate, an aqueous solution of polyacrylic acid having a low molecular weight is added to the spent sulfite liquor in an entrance stage of the multiple-effect sulfite liquor in an entrance stage of the multiple-effect evaporating system and an aqueous solution of a copolymer of sulfonated styrene and maleic anhydride or an aqueous solution of a polyacrylic acid having a low molecular weight is added to the spent sulfite liquor in at least one succeeding stage of the multiple-effect evaporating system.