Determination of sodium salts contents in black liquor evaporators and their influence over scale formation

• Grant number: 08/00041-0
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2008
• End date: July 31, 2009
• Field of knowledge: Engineering - Chemical Engineering - Chemical Process Industries
• Principal Investigator: José Vicente Hallak d´Angelo
• Grantee: José Vicente Hallak d´Angelo
• Host Institution: Faculdade de Engenharia Química (FEQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Brazil is today the sixth greatest cellulose manufacturer in the world, the first one in short fiber cellulose and it is also the eleventh greatest paper manufacturer. These positions have been reached due to many investiments made in process expansions and technological research and also thanks to the great quality and quantity of natural resources. To keep this competitivity of our country it is necessary to continue investing in researches that contribute to improve the quality of products and processes in this sector. This increasing in the production rate has also caused an increasing in the quantity of black liquor generated in the wood digestion process. This liquor is reused in the process to produce energy and to recover inorganic chemicals in the recovery unit. Today one of the main problems of this unit is the formation and growing of scales deposits in the evaporators and concentrators of black liquor, caused by the presence of non-process elements (NPEs) and/or compounds of these elements that form deposits under specific process conditions. In the evaporators, where black liquor is concentrated to be burned, the presence of sodium salts leads to scaling problems, causing obstructions in the tubes of the equipment, working flaws and constant maintenance stops that prejudice the production. This research project aims to characterize sodium carbonate and sodium sulphate contents in black liquor in process streams of the evaporation stage in the recovery unit of a pulp and paper mill, in order to evaluate their influence in scaling formation. The characterization of these compounds, associated to the NPE sodium, is of great relevance to understand the scaling process and then to propose some measures to reduce this undesirable effect, with significant improvement to the process. (AU)