METHOD OF CLOSED WATER CIRCULATION IN PRODUCTION OF UNBLEACHED SULFATE PULP AND CARDBOARD Russian patent published in 2000 - IPC

FIELD: methods of utilization of circulating and sewage waters particularly, of those in production of unbleached sulfate pulp and cardboard. SUBSTANCE: method includes gathering of used water from stages of production of unbleached sulfate pulp and cardboard, manufacture of corrugated containers and coated cardboard; and biological and chemical treatment of gathered waters. One flow of treated water is returned to pulp and cardboard production. To exclude discharge of used waters to sewage system of digesting-washing shop, water used for cooling of heat- exchange apparatuses of turpentine blowers is directed to accumulating tank of utilization of steam-air mixture. Further on, used waters of digesting-washing shop together with condensate of evaporation stations are used for washing of pulp and slimes of lime caustisizing and regeneration shop and supplied to stages of evaporation and regeneration together with spent caustic from sulfate digestion. The second flow of treated circulating sewage is supplied to scrubbers of heat and power generating station supplying pulp-cardboard production with heat and power. EFFECT: higher efficiency of operation of evaporation station, prevented increase of circulating water mineralization by exclusion of discharge of used waters of digesting-washing shop to sewage treatment works. 1 dwg