Thermal pretreatment of black liquor

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Within this project, the possibility of using pyrolysis of black liquor from kraft pulp production prior to combustion in the recovery boiler is investigated. A controlled and slow heating rate minimizes the amount of alkali (sodium and potassium) that are ejected during devolatilization and creates opportunity for several improvements with retained chemical recovery performance.

Both the corrosion and the amount of deposits are reduced. Reduced corrosion gives possibilities of increased steam data to produce more electricity and it also decrease the abrasion which reduces operating related problems. Reduced amounts of deposits lead to a more effective heat transfer and a reduced maintenance. This project contains one experimental part, one theoretical part and one system analysis part where the effect of the process step is evaluated within the whole chemical recovery.