METHOD OF EVAPORATION OF HOT BLACK LIQUOR, WHICH IS OBTAINED FROM COOKING PROCESS DURING PRODUCTION OF PULP Russian patent published in 2024 - IPC D21C11/10 

FIELD: pulp and paper industry.

SUBSTANCE: invention relates to pulp and paper industry, namely to a method for evaporation of hot black liquor obtained from the process of cooking hardwood and a mixture of hardwood and softwood during production of pulp. In the disclosed method, black liquor is introduced into a multistage evaporation, and at the first evaporation stage, aqueous solutions of surfactants are successively introduced: nonionic pentaoxyethylated ester of tridecanoic acid monoethanolamide of the formula C₁₂H₂₅CONHCH₂CH₂O(C₂H₄O)₅H (nonionic surfactant 1), cationic surfactant of dodecyldimethylbenzylammonium chloride of formula {C₁₂H₂₅(CH₃)₂(CH₂C₆H₅)N}Cl and a nonionic surfactant of oxyethylated monoalkylphenol based on propylene trimers of formula C₉H₁₉C₆H₄O(C₂H₄O)₆H (nonionic surfactant 2).

EFFECT: invention increases output of foaming substances in the form of sulphate soap at the temperature of the liquor supplied for evaporation by additional coagulation and demulsification of organic substances when processing black liquor, with simultaneous reduction of the amount of contaminants on the surface of the heat exchanger with reduction of evaporation time.

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