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

摘要

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.