METHOD AND SYSTEM FOR TREATING SPENT PULPING LIQUOR

A system (10) for treating spent pulping liquor (14) comprising lignin to provide green liquor (47) is disclosed. The system (10) comprises an evaporator (22)， a recovery boiler (34)， at least one filter (58， 74)， and a green liquor plant (46). The evaporator (22) concentrates a first stream (18) of the spent pulping liquor (14) to provide a concentrated pulping liquor (30). The recovery boiler (34) incinerates the concentrated pulping liquor (30) to provide a smelt (42). The at least one filter (58， 74) filters a second stream (54) of the spent pulping liquor (14) to remove lignin therefrom to provide a permeate (66， 82). The green liquor plant (46) is for dissolving the smelt (42) from the recovery boiler (34) in the permeate (66， 82) from the at least one filter (58， 74) to provide green liquor (47). Also disclosed is a method for treating spent pulping liquor (14) to provide green liquor (47). A system (10) for treating spent pulping liquor (14) comprising lignin to provide green liquor (47) is disclosed. The system (10) comprises an evaporator (22)， a recovery boiler (34)， at least one filter (58， 74)， and a green liquor plant (46). The evaporator (22) concentrates a first stream (18) of the spent pulping liquor (14) to provide a concentrated pulping liquor (30). The recovery boiler (34) incinerates the concentrated pulping liquor (30) to provide a smelt (42). The at least one filter (58， 74) filters a second stream (54) of the spent pulping liquor (14) to remove lignin therefrom to provide a permeate (66， 82). The green liquor plant (46) is for dissolving the smelt (42) from the recovery boiler (34) in the permeate (66， 82) from the at least one filter (58， 74) to provide green liquor (47). Also disclosed is a method for treating spent pulping liquor (14) to provide green liquor (47).