Flow through Packed and Fluidized Beds
Chemical engineering operations commonly involve the use of packed and fluidized beds. These are devices in which a large surface area for contact between a liquid and a gas (absorption, distillation) or a solid and a gas or liquid (adsorption, catalysis) is obtained for achieving rapid mass and heat transfer, and particularly in the case of fluidized beds, catalytic chemical reactions. You will find a good deal of information about flow through packed and fluidized beds in the book by McCabe, Smith, and Harriott (1) and Perry’s Handbook (2). Here, only a brief summary is given. First, let us consider flow through a packed bed.
Parameters Affecting Dust Collector Efficiency for Pneumatic Conveying: A Review
In a context of energy abundance for industrial applications, industrial systems are exploited with minimal attention to their actual energy consumption requirements to meet the loads imposed on them. As a result, most of them are used at maximal capacity, regardless of the varying operational conditions. First, the paper studies pneumatic conveying systems and thoroughly reviews previously published work. Then, we overview simulations and operating data of the experimental parameters and their effects on the flow characteristics and transport efficiency. Finally, we summarize with a conclusion and some suggestions for further work. The primary goal of this study is to identify the parameters that influence the energy consumption of industrial dust collector systems. It is differentiated from previously published overviews by being concentrated on wood particles collection systems. The results will permit a better selection of an appropriate methodology or solution for reducing an industrial system’s power requirements and energy consumption through more precise control. The anticipated benefits are not only on power requirement and energy consumption but also in reducing greenhouse gas emissions. This aspect shows more impacts in regions that rely on electricity supplied by thermal power stations, especially those that use petrol or coal.
Steady incompressible laminar flow in porous media
Steady incompressible laminar flow in porous media is studied. The volume averaging technique is revisited resulting in a new averaging approach to the pressure gradient term. The difference between the traditionally obtained volume averaged equation for very small flow rate and Brinkman's equation is resolved. The Kozeny—Carman theory is modified. By including a two-dimensionally modelled tortuosity and curvature ratio as well as pore cross-sectional area variation, a new semi-empirical equation for the pressure drop for flow through porous media is obtained. The pressure drop dependence on the porosity e for Darcy's flow region is established as e−113(1 − e)2 as opposed to e−3(1 − e)2 in the original Kozeny—Carman's theory. A modified Reynolds number is also defined. The regions of Darcy's flow and Forchheimer's flow are unified. The wall effects are incorporated into the unified pressure drop equation. The final form of the normalized pressure drop equation for a one-dimensional medium is given by for ds = d′s/D < 0.75. Here fv is the normalized pressure drop factor, — Δp′ is the pressure across a fixed thickness L of the porous bed, e is the porosity, d′s is the equivalent spherical particle diameter, D is the bed diameter, U is the superficial velocity or fluid discharge rate, μ is the dynamic viscosity of the fluid and Rem is the modified Reynolds number. The one-dimensional pressure drop equation is also modified to give a shear factor for use with the volume averaged Navier—Stokes equation and it is given as where F is the shear factor and Rev is the local modified Reynolds number. The semi-theoretical model was tested with a available and new experimental pressure drop data for packed beds. Further comparison was made with experimental pressure drop data for flow in a fibrous mat. The model was found to correlate well for the whole range of Reynolds number, wall effects and porosity studied.