Exergy analysis of a multistage evaporation system for black liquor concentration

• Autor(a) principal: Rodrigues, Lucas Nunes
• Data de Publicação: 2021
• Outros Autores: Silva, Luiz Felipe Rodrigues, Borges, Matheus de Sousa, Sousa, Karine Matos, Lima, Francisco Valdivino Rocha, Fortes, Anderson Felipe Chaves
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Research, Society and Development
• Texto Completo: https://rsdjournal.org/index.php/rsd/article/view/22835
• topic: Licor negro; Evaporação; Exergia; Termodinâmica; Eficiência.; Licor negro; Evaporación; Exergía; Termodinámica; Eficiencia.; Black liquor; Evaporation; Exergy; Thermodynamics; Efficiency.

The pulp and paper industries in Brazil are large consumers of energy, offering an ideal region for the development of eucalyptus forests. The Kraft process is the most used in the country as it is capable of reusing chemical products, with black liquor being one of the by-products, a complex substance with organic and inorganic composition. To obtain economic and environmental viability, the inorganic portion must be reacquired in a recovery plant to be reused, with the plant having a multi-stage evaporation system, responsible for concentrating the liquor to be burned in the recovery boiler. In light of the above, the objective of this work was the development and validation of a phenomenological mathematical model that would represent the multistage evaporation system, to carry out a study of inlet temperature and pressure that would bring the best results in terms of steam savings, exergetic efficiency, exergy destruction and black liquor solids content. Thus, the best inlet conditions and evaporators that have higher exergy destruction rates were found. For this, the model was built based on related research works, using mass, energy and phase balance balances, as well as satisfactorily portraying the results found by the reference author, obtaining the largest deviation of 0.2%. This work allowed an advance in the understanding of the phenomena involved and the optimization of this process, aiming at an improvement in the energy consumption of the environment.