What is the minimum fluidization velocity?

What is the 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 the minimum fluidized bed velocity?

Fluidized-Bed Combustion Boilers Determine the minimum fluidization velocity of 300 μm sand, if the density of sand is 2500 kg/m3, density of gas is 0.316 kg/m3, and viscosity of gas is 4.49×10−5 N.s/m2. (Ans.: vm=0.0368 m/s) 5.2.

What is minimum fluidizing velocity and when does it occur?

2.1 Minimum fluidization velocity calculation. This is generally defined as minimum superficial velocity at which the drag force and the upward buoyant force due to the fluid is balanced by the weight of the particles illustrated in Figure 3.

What is maximum fluidization velocity?

The point at which the drag on an individual particle is about to exceed the gravitational force exerted on it is called the maximum fluidization velocity. Maximum. velocity through. the bed ut.

What does the minimum fluidization velocity in the bed depend 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 [12].

How do you calculate fluidisation velocity?

Kozeny-Carman gave the formula of calculation of the minimum fluidization velocity for a very small particle size with the Remf < 10 in Eq. (14) described in Yates [16]. For spherical particles or sphericity equivalent, the bed voidage of the minimum fluidization εmf = 0.4 ÷ 0.45.

What is terminal velocity in a fluidized bed?

A particle in a bed has a different field of reference. Instead of a body falling through a stagnant fluid, in a fluidized bed, the fluid is moving the body. A particle’s terminal velocity is the lowest gas velocity that causes particles to start moving with the gas.

What does the minimum fluidization velocity in the bed depends on 1 point size distribution of solids pumping power diameter of bed all of the mentioned?

Explanation: Solids size, power and diameter are considered while calculating the minimum fluidization velocity.

What is the relationship between minimum fluidisation velocity and the mean particle size?

The experimental minimum fluidization velocity is about equal to the theoretical for the small particles (100-200 µm). For the larger particles the experimental minimum fluidization velocities are significantly lower than the theoretical.

How does particle size affect minimum fluidization velocity?

Minimum fluidization velocity was increased with particle diameter, where it was 0.225 m/s for the 600 microns particles. The density effect was analyzed for 600 microns particles with seven different density values and the minimum fluidization velocity again showed proportionality to the density.

What is superficial velocity in fluidization?

Superficial velocity (or superficial flow velocity), in engineering of multiphase flows and flows in porous media, is a hypothetical (artificial) flow velocity calculated as if the given phase or fluid were the only one flowing or present in a given cross sectional area.

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