초록 ▼

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

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.

대표청구항 ▼

A method of controlling the sulfidity of a sulfate cellulose mill, comprising the steps of: (a) generating black liquor containing sulfur compounds by treating wood chips in white liquor in a digester including cooking said wood chips at a cooking temperature; (b) evaporating said black liquor in a

A method of controlling the sulfidity of a sulfate cellulose mill, comprising the steps of: (a) generating black liquor containing sulfur compounds by treating wood chips in white liquor in a digester including cooking said wood chips at a cooking temperature; (b) evaporating said black liquor in a multi-stage evaporator system, including a last stage; (c) prior to said last stage of said multi-stage evaporator system, pressure heating said black liquor to a predetermined temperature higher than said cooking temperature and retaining said heated black liquor at said predetermined temperature for a predetermined time, to generate sulfur containing gases; (d) removing said sulfur containing gases from said black liquor; (e) producing white liquor from said black liquor from step (d); (f) adjusting the sulfidity of said white liquor produced in step (e) by controlling the predetermined temperature and retention time from step (c); and (g) utilizing said sulfidity-controlled white liquor in the practice of step (a).