Ergun equation

How do you calculate pressure drop in a packed bed?

ΔP = total pressure drop in packed bed, lb/in. μ = fluid viscosity, cP (1 cP = 2.419lb/ft h). Calculate the pressure drop in a 60 ft length of 1 1/2-in.THE EQUATIONS.

Packed bed length, ft60
Density of fluid at flowing conditions, lb/ft30.413
Fluid viscosity, cP0.0278

How do you find the minimum fluidization velocity?

The minimum fluidization velocity can be calculated by equating the pressure–drop across the fixed packed–bed, calculated from Ergun’s equation to that from the expression for fluidized bed under particulate (smooth) conditions.

How do you calculate Voidage of a bed?

Subtract the density of the sand from the specific gravity of the sand, then divide the result by the specific gravity to find the voidage (proportion of empty space in the dry sand). For example, with a density for dry sand of 1.5 and a specific gravity of 2.5, you have a voidage of (2.5 – 1.5)/2.5 = 0.4.

What is minimum fluidization velocity?

The minimum fluidization velocity (Umf), defined as the superficial gas velocity at which the drag force of the upward moving gas becomes equal to the weight of the particles in the bed, is one of the most important parameters associated with a fluidized bed system.

What is bed voidage?

is the bed voidage, i.e. the fraction of the bed volume that is occupied by the voids (the fluid spaces between the particles) is the apparent density of bed particles. is the density of the fluidising fluid. is the acceleration due to gravity. is the total mass of solids in the bed.

What is meant by pressure drop?

Simply put, pressure drop is the difference in total pressure between two points in a fluid-carrying network. When a liquid material enters one end of a piping system, and leaves the other, pressure drop, or pressure loss, will occur.

What is pressure drop in packed column?

The horizontal axis is the logarithmic value of the gas velocity G, and the vertical axis is the logarithmic value of pressure drop per height of packing [ pressure drop in a packed bed is the result of fluid friction that is created by the flow of gas and liquid around the individual solid packing materials ].

What does the minimum fluidization velocity in the bed depends on?

The minimum fluidization velocity depends on particle moisture content; increasing moisture content increases the minimum fluidization velocity. For wet particle fluidization, the bed pressure drop for velocities above the minimum fluidization point gradually increases with increasing gas velocity (Hajidavalloo, 1998).

What is fluidization and its types?

Fluidization (or fluidisation) is a process similar to liquefaction whereby a granular material is converted from a static solid-like state to a dynamic fluid-like state. This process occurs when a fluid (liquid or gas) is passed up through the granular material.

What is fluidization process?

Fluidization is defined as a method to keep solid particles floating in an upward direction (Figure 5) in a flow of gas or liquid. In freezing, fluidization occurs when particles of a similar shape and size are subjected to an upward stream of low-temperature air.

What is the relationship between sphericity and Voidage?

It is found that as the sphericity decreases, the bed voidage increases. Increasing the particle density and initial bed height causes the voidage to decrease due to the strong compression in the bed. The decrease in the voidage can lead to a decrease in the minimum fluidization velocity.

How do you find the void fraction?

The void fraction can be calculated from knowing the total volume of the test tube between the valves. This method works best at low vapor qualities where the liquid fraction is large and is less and less accurate as one enters annular flow where the liquid fraction becomes less and less.

How do you calculate superficial velocity?

The velocity of fluid moving through a pipe, defined as the volumetric flow rate of that fluid divided by the cross-sectional area. In monophasic flow, it is equal to the mean velocity of the fluid.

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