Liquid Fluidization

Liquid fluidization can be encountered in industrial practice in a variety of processes including particle classification and separation and backwashing of filter media. In any fluidized system, overall bed height changes with fluid velocity. This chapter introduces the correlation between voidage and fluid velocity and presents some observations on the apparent behaviour of liquid-fluidized beds. Liquid fluidization has long been used with multi-solids, in which different particle species can mix or segregate. In binary solids sorting, particles of similar sizes are separated, with the denser component settling to the bottom of the fluidized bed and the less dense one rising towards the surface. Layer inversion has been observed to occur upon changing the fluid velocity or the mixture composition. Transport of heat and mass in liquid-fluidized beds has been the subject of a large number of research studies. The chapter also provides an account of some correlating result for practical purposes

Processo da retrolavagem em filtros de areia usados na irrigação localizada Backwash process in sand filters used in localized irrigation

O processo da retrolavagem consiste na passagem da água através do filtro em sentido contrário ao fluxo de filtragem com o objetivo de remover partículas orgânicas e inorgânicas retidas no meio filtrante. O projeto de filtros de areia com configurações ineficientes e a ocorrência de condições operacionais inadequadas contribuem para limitar o desempenho desse processo, causando deficiências na limpeza dos meios filtrantes e comprometendo o funcionamento dos sistemas de irrigação localizada. O objetivo do presente trabalho é proporcionar uma revisão sobre os conceitos associados ao processo da retrolavagem nos filtros de areia, relacionando informações existentes na literatura com experiências de laboratório. Foi gerado um texto básico com informações técnico-científicas sobre o tema, visando a criar um momento de reflexão sobre o processo de retrolavagem e a contribuir para a melhoria do desempenho desses equipamentos na irrigação localizada.<br>The backwash process consists of water passing through the filter in the opposite direction of the filtering flow to remove organic and inorganic particles of media filter. Inefficient sand filters designs and the occurrence of inadequate operating conditions contribute to restrict the process performance, causing deficiencies in the filter cleaning and compromise the operation of localized irrigation systems. The objective of this study is to provide a review about concepts associated with the backwash process in sand filters, relating literature information with laboratory experiments. A basic documentation was produced with technical and scientific information on this subject to create a reflection about the backwash process and contribute to the improvement of the equipment performance in the localized irrigation