Hydrodynamic Study of Swirling Fluidized Bed and the Role of Distributor

The study aims to the hydrodynamic characteristics of swirling fluidized bed, using large particles (Geldart D-type) selected from locally available agricultural produce (coffee beans and black pepper). The important variables considered in the present study include percentage area of opening, angle of air injection and the percentage useful area of the distributor. A total of seven distributors have been designed and fabricated for a bed column of 300 mm, namely single row vane type distributors (15˚ and 20˚ vane angle), inclined hole type distributors (15˚ and 20˚ vane angle) and perforated plate distributors. The useful area of distributor of single row vane type, three now vane-type and inclined hole-type distributors are respectively 64%,91% and 94%. The hydrodynamic parameters considered in the present study include distributor pressure drop, air velocity, minimum fluidizing velocity, bed pressure drop, bed height and the bed behaviour. It has been observed that, in general, the distributor pressure drop decreases with an increase in the percentage area of opening, Further, and increase in the area of opening above 17% will not considerably reduce the distributor pressure drop. In the present study, for the distributor with an area of opening 17%, and corresponding to the maximum measured superficial velocity of 4.33 m/s, the distributor pressure drop obtained was 55.25mm of water. The study on the bed behavior revealed that, in a swirling fluidized bed, once swirl motion starts, the bed pressure drop increases with superficial velocity in the outer region and it decreases in the inner region. This means that, with higher superficial velocity, the air might get by-passed through the inner boundary of the bed (around the cone). So, depending on the process for which the bed is used, the maximum superficial velocity is to be limited to have an optimum bed performance.

Acid-Base. Surface Electron Donatin6 &.Catai.Ytlc Properties Of Some Binary Mixed Oxides Containing Rare Earth Elements

Catalysis research underpins the science of modern chemical processing and fuel technologies. Catalysis is commercially one of the most important technologies in national economies. Solid state heterogeneous catalyst materials such as metal oxides and metal particles on ceramic oxide substrates are most common. They are typically used with commodity gases and liquid reactants. Selective oxidation catalysts of hydrocarbon feedstocks is the dominant process of converting them to key industrial chemicals, polymers and energy sources.[1] In the absence of a unique successfiil theory of heterogeneous catalysis, attempts are being made to correlate catalytic activity with some specific properties of the solid surface. Such correlations help to narrow down the search for a good catalyst for a given reaction. The heterogeneous catalytic performance of material depends on many factors such as [2] Crystal and surface structure of the catalyst. Thermodynamic stability of the catalyst and the reactant. Acid- base properties of the solid surface. Surface defect properties of the catalyst.Electronic and semiconducting properties and the band structure. Co-existence of dilferent types of ions or structures. Adsorption sites and adsorbed species such as oxygen.Preparation method of catalyst , surface area and nature of heat treatment. Molecular structure of the reactants. Many systematic investigations have been performed to correlate catalytic performances with the above mentioned properties. Many of these investigations remain isolated and further research is needed to bridge the gap in the present knowledge of the field.