3. Introductionn Packed and fluidized beds are one of the most important uses in

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3. Introductionn Packed and fluidized beds are one of the most important uses in chemical engineering operations. Typically, they are a cylindrical column filled with a packing material, which fluid flows at such a high velocity that the bed is loosened and the particle-fluid mixture behaves as though it is a fluid. There are many types of fluidized beds such as circulating fluidized beds (CFB) and vibratory fluidized beds. Also, there are many types of packing material like random packing which includes pall rings and ranching rings and structured packing which includes meatpacker and flexi pack. Packing material can have many shapes, roughness and sizes. The most two important factors that must be considered when selecting a packing material are surface area and void friction. The velocity of the fluid has to be sufficiently high to suspend, or fluidize, the particles within the column, in order to provide a large surface area for the solid and the fluid to contact, which is the chief advantage of fluidized beds. i There are many applications of fluidized beds. They are used as a technical process because they have a good ability to promote high levels of contact between fluids and solids. Fluidization also is widely used in physical operations like mixing or heating, or in chemical processes such as reactions of solids with gases or reactions involving gases with solid catalysts. Fluidized beds are also used to increase the efficiency of dryers by allowing the entire surface of the drying material to be suspended, and therefore exposed to the 151 Beside the great advantages of fluidized bed, such as their high levels in intermixing of the particulate phases, they also have disadvantages. One of the problems in the fluidized bed that sometimes particles become entrained, or blown along with the flow, which can be costly and problematic to repair Also, they are so expensive and they need extra power input. In this experiment, the flow rates of water and air were varied in order to study their effect on the pressure drop of the fluid passing through the solid height of the bed. This experiment is important because these beds wl increase the surface area between reactants, which will make the reaction proceed very fast and produce more products. Also, this experiment will help to know the suitable flow rates that may increase the products. porous in the bed and the

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Hi

Introduction

Two very important type of beds used in chemical engineering are packed and fluidized beds. They are cylindrical columns filled with packing material. Under very high velocity of fluid, the particles suspend in fluid making the mixture behaving as a fluid and this is the preferred kind of flow of fluid in beds. Fluidized beds are of many types e.g. circulating fluidized bed, vibratory fluidized bed, etc. Similarly, there are different types of packing material of different sizes, shapes and roughness all incorporating two important properties crucial for selection of packing material i.e. packing material surface area and void fraction. Example of packing materials are pall rings, ranching rings and structured packing which includes meatpacker and flexi pack.

Fluidized beds have many applications. Due to their good ability to promote high contact levels of solid and fluid, they are used in technical process. Their wide application is seen in mixing and heating process, process involving solid-gas reactions where solid acts as catalysts. With fluidized beds, efficiency of dryers can be increased because the air suspends the drying material and hence increases the area of contact.

With so many advantages, fluidized beds have disadvantages too. The particles can become entrained and they can be flown away by the fluid. The repair is very costly let alone the fact they are expensive and consumes extra power.

In this experiment, varying flow rates of water and air were passed through a solid porous bed and pressure drop is observed. Since the particles increases surface area of reaction, therefore, different yield of product is obtained at different flow rates. This way, we can get an idea about the flow rate which will yield the maximum product.

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