Estudo da velocidade mínima de fluidização através de ensaios reológicos de materiais particulados com diferentes propriedades superficiais
Carregando...
Arquivos
Citações na Scopus
Tipo de produção
Dissertação
Data
2017
Autores
Buratini, E. R.
Orientador
Condotta, R.
Periódico
Título da Revista
ISSN da Revista
Título de Volume
Citação
BURATINI, E. R. Estudo da velocidade mínima de fluidização através de ensaios reológicos de materiais particulados com diferentes propriedades superficiais. 2017. 180 f. Dissertação (Mestrado em Engenharia Química ) - Centro Universitário FEI, São Bernardo do Campo, 2017. Disponível em: . Acesso em: 3 ago. 2018.
Texto completo (DOI)
Palavras-chave
Fluidização,Sólidos,Particulas
Resumo
A determinação da velocidade mínima de fluidização é obtida a partir do levantamento em laboratório das curvas de perda de carga em função de ar injetado em um leito fluidizado clássico, em um reômetro de pós e através de correlações matemáticas previamente levantadas. As amostras envolvidas neste trabalho consistiram de hidróxido de alumínio e hidróxido de magnésio com e sem revestimento (9 - 12µm), aluminas fluoretada e calcinada (90 - 100µm), caulim, calcário e quartzo, com tamanho entre 40 - 60µm. O comportamento dos sólidos durante
a fluidização em um leito clássico foi bem diferente: os coesivos, dado pelos hidróxidos de alumínio e magnésio, apresentaram formação de canal preferencial enquanto que os sólidos classificados como areias , as aluminas calcinada e fluoretada, permitiram a visualização do início da fluidização, com formação de bolhas. Em paralelo, o teste de aeração foi realizado em um reômetro de pós, um equipamento que não sofre com a influencia do operador durante os testes. No reômetro de pós, foi possível a determinação da velocidade mínima de fluidização
para os pós coesivos, aluminas e os compostos intermediários, com baixas variações de resultados. Para compreender os diferentes comportamentos, as propriedades das partículas, tal como diâmetro, densidade, morfologia e comportamento físico no leito de partículas (testes de energia básica de fluxo, compressibilidade, permeabilidade e teste de cisalhamento foram determinadas). Esses testes permitiram verificar que as partículas com maior tamanho, as aluminas calcinada e fluoretada, apresentam menor interação interparticular, sendo menos
coesivas, fluindo mais facilmente. Para os compostos de hidróxidos de magnésio e alumínio, foram estudados o efeito de dois revestimentos e concluiu-se que revestí-los com ácido graxo gera aglomeração das partículas enquanto o revestimento de organosilicato desaglomera as partículas, permitindo a esses compostos maior fluidez ao material. Os compostos com baixo tamanho de partícula possuem maiores interações interparticulares. Dessa forma, neste trabalho concluiu-se que o leito fluidizado é recomendado para partículas de tamanho superior a 100
µm, em que existem menores interações interparticulares. Enquanto o reômetro de pós e algumas correlações matemáticas obtiveram melhores resultados para partículas de tamanhos inferiores a 40µm, de alta interação interparticular, coesivas e finas.
The determination of the minimum fluidization velocity is obtained from the laboratory survey of the pressure drop curves as a function of injected air. In addition, it is possible to determine it from mathematical correlations. In this work, the mininum fluidization velocity was determined by laboratory tests carried out in a classic fluidized bed, in a powder rheometer and through previously raised mathematical correlations. The samples involved in this work consisted of aluminum hydroxide and magnesium hydroxide with and without coating (9- 12µm), fluorinated and calcined alumina (90-100µm), kaolin, limestone and quartz, with a size between 40-60µm. The behavior of the solids during the fluidization in a classic bed was very different: the cohesive ones, given by the hydroxides of aluminum and magnesium, presented preferential channel formation while the solids classified as "sand", the calcined and fluoride alumines, allowed the visualization of fluidization, with formation of bubbles. In parallel, the aeration test had done on a powder rheometer, an equipment that is not influenced by the operator during the tests. In the powder rheometer, it was possible to determine the minimum fluidization velocity for cohesive powders and for larger particles (aluminas). To understand the different behaviors, the properties of the particles, such as diameter, density, morphology and physical behavior in the particle bed (basic flow energy tests, compressibility, permeability and shear test were performed). These tests concluded that the particles with larger size, the calcined and fluoridated alumines, do not have interparticular interaction, being less cohesive, flowing easily. For the magnesium and aluminum hydroxide compounds, the effect of two coatings was studied and it was found that coating them with fatty acid generates agglomeration of the particles while the organosilicate coating deagglomerates the particles, allowing such compounds to be more fluid in the material. Compounds with low particle size have higher interparticular interactions. Thus, in this work it was concluded that the fluidized bed is recommended for particles larger than 100 µm, in which there are smaller interparticular interactions. While the rheometer of powders and some mathematical correlations obtained better results for particles of sizes smaller than 40µm, high interparticular interaction, cohesive and fine.
The determination of the minimum fluidization velocity is obtained from the laboratory survey of the pressure drop curves as a function of injected air. In addition, it is possible to determine it from mathematical correlations. In this work, the mininum fluidization velocity was determined by laboratory tests carried out in a classic fluidized bed, in a powder rheometer and through previously raised mathematical correlations. The samples involved in this work consisted of aluminum hydroxide and magnesium hydroxide with and without coating (9- 12µm), fluorinated and calcined alumina (90-100µm), kaolin, limestone and quartz, with a size between 40-60µm. The behavior of the solids during the fluidization in a classic bed was very different: the cohesive ones, given by the hydroxides of aluminum and magnesium, presented preferential channel formation while the solids classified as "sand", the calcined and fluoride alumines, allowed the visualization of fluidization, with formation of bubbles. In parallel, the aeration test had done on a powder rheometer, an equipment that is not influenced by the operator during the tests. In the powder rheometer, it was possible to determine the minimum fluidization velocity for cohesive powders and for larger particles (aluminas). To understand the different behaviors, the properties of the particles, such as diameter, density, morphology and physical behavior in the particle bed (basic flow energy tests, compressibility, permeability and shear test were performed). These tests concluded that the particles with larger size, the calcined and fluoridated alumines, do not have interparticular interaction, being less cohesive, flowing easily. For the magnesium and aluminum hydroxide compounds, the effect of two coatings was studied and it was found that coating them with fatty acid generates agglomeration of the particles while the organosilicate coating deagglomerates the particles, allowing such compounds to be more fluid in the material. Compounds with low particle size have higher interparticular interactions. Thus, in this work it was concluded that the fluidized bed is recommended for particles larger than 100 µm, in which there are smaller interparticular interactions. While the rheometer of powders and some mathematical correlations obtained better results for particles of sizes smaller than 40µm, high interparticular interaction, cohesive and fine.