Otimização da destilação da mistura água-acetona via estudo hidrodinâmico dos meios de contato
Arquivos
Data
2019-11-26
Autores
Nunes, Thais de Souza [UNIFESP]
Orientadores
Nasser Junior, Roberto [UNIFESP]
Tipo
Trabalho de conclusão de curso de graduação
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O acetato de celulose passou a ser utilizado na indústria têxtil para fabricação de fibras sintéticas que, quando processadas, formam um tecido de bastante qualidade e maciez, similarmente à seda. O seu uso industrial requer solubilização em acetona e, consequentemente, recuperação deste solvente a partir de operações unitárias de absorção e destilação. A partir de dados de fotografias realizadas em uma coluna de destilação e, baseado em conceitos termodinâmicos de equilíbrio da mistura binária água-acetona, bem como relações empíricas e métodos computacionais, torna-se possível validar e aprimorar os processos envolvidos na separação da mistura estudada. O presente trabalho buscou otimizar a etapa de destilação, que requer demanda energética significativa, fazendo a transposição de internos, comparando a configuração de pratos com recheios estruturado, mais especificamente o recheio EuroPack 250Y, sendo que está última foi estudada em duas situações distintas. A capacidade para pratos e para o primeiro cenário com recheio estruturado foi mantida, em ambas alcançou-se a composição de 97,6% de acetona no destilado e de 34 ppm de acetona no fundo para a mesma vazão de alimentação. O grande diferencial quando comparadas as duas situações, é que a coluna de recheio apresentou uma redução expressiva no diâmetro de 33%. Entretanto, o ponto negativo é que foi necessário aumentar a razão de refluxo (de 3,82 para 4,59) e a vazão de vapor (de 329,95 kmol/h para 368,67 kmol/h), podendo impactar em custos adicionais. Procurando aprimorar, como a corrente de fundo com quantidade pequena de acetona retorna à destilação, sem maiores prejuízos, foi estabelecido um segundo cenário para a coluna recheada, a fim de diminuir a vazão de vapor requerida. Para tanto aumentou-se o limite do teor de acetona no produto de fundo, estabelecendo composição de 405 ppm. Desse modo, foi observado uma redução significativa de vapor necessário, que passou a ser de 306,36 kmol/h. Já em termos financeiros, estimou-se que tais modificações se convertem em uma economia de aproximadamente R$ 1,1 milhões na construção da coluna e de R$ 500 mil/ano na quantidade de vapor requerido.
The cellulose acetate has been used in the textile industry to manufacture synthetic fibers which, when processed, form a fabric of quite good quality and softness, similar to silk. Its industrial use requires solubilization in acetone and, consequently, recovery of this solvent from unitary operations of absorption and distillation. Based on data from a Photography available and based on thermodynamic concepts of the binary water-acetone equilibrium system, as well as empirical relations and computational methods, it becomes possible to validate and improve the processes involved in the separation of the studied mixture. The present work sought to optimize the distillation stage, which requires significant energy demand, by transposing internals, comparing the configuration of trays with structured pack, more specifically the EuroPack 250Y, this last was studied in two different situations. The capacity for trays and the first set using structured pack was maintained, in both the composition was 97.6% of acetone in the distillate and 34 ppm of acetone in the bottom for the same flow rate. The great difference when comparing the two situations, is that the packed column presented a reduction in diameter of 33%. However, the downside is that it was necessary to increase the reflux ratio (from 3,82 to 4,59) and vapor flow (from 329,95 kmol/h to 368,67 kmol/h), which could impact additional costs. Seeking to improve, as the bottom stream with small amount of acetone returns to distillation, without significant damage, a second set was established for the packed column, in order to decrease the required stream flow. For this purpose, the limit of acetone content in the bottom product was increased, establishing a composition of 405 ppm. Thus, a significant reduction in the required steam was observed, which became 306,36 kmol/h. In financial terms, it has been estimated that such modifications will result in savings of approximately R$ 1.1 million in column construction and R$ 500.000/year in the amount of steam required.
The cellulose acetate has been used in the textile industry to manufacture synthetic fibers which, when processed, form a fabric of quite good quality and softness, similar to silk. Its industrial use requires solubilization in acetone and, consequently, recovery of this solvent from unitary operations of absorption and distillation. Based on data from a Photography available and based on thermodynamic concepts of the binary water-acetone equilibrium system, as well as empirical relations and computational methods, it becomes possible to validate and improve the processes involved in the separation of the studied mixture. The present work sought to optimize the distillation stage, which requires significant energy demand, by transposing internals, comparing the configuration of trays with structured pack, more specifically the EuroPack 250Y, this last was studied in two different situations. The capacity for trays and the first set using structured pack was maintained, in both the composition was 97.6% of acetone in the distillate and 34 ppm of acetone in the bottom for the same flow rate. The great difference when comparing the two situations, is that the packed column presented a reduction in diameter of 33%. However, the downside is that it was necessary to increase the reflux ratio (from 3,82 to 4,59) and vapor flow (from 329,95 kmol/h to 368,67 kmol/h), which could impact additional costs. Seeking to improve, as the bottom stream with small amount of acetone returns to distillation, without significant damage, a second set was established for the packed column, in order to decrease the required stream flow. For this purpose, the limit of acetone content in the bottom product was increased, establishing a composition of 405 ppm. Thus, a significant reduction in the required steam was observed, which became 306,36 kmol/h. In financial terms, it has been estimated that such modifications will result in savings of approximately R$ 1.1 million in column construction and R$ 500.000/year in the amount of steam required.