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• JadderMedina

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FLUIDIZATION The packed bed is extended when the force of pressure drop is the same to the weight of packed solids. Then, the porosity of solids is longer than before and the packed bed is a bed fluidized now.

Packed bed

Fluidized bed

Pneumatic transport

Geldart’s Powder Classification

Geldart’s Powder Classification

Pressure drop in fluidized beds

Forces balance −Δ P =(1− ε )∗( ρ p −ρ )∗g L Replacing into the Ergun equation 2 2 150∗(1−ε ) ∗μ∗v 1.75∗ρ∗v ∗(1−ε ) + =(1− ε)∗( ρ p −ρ )∗g 2 2 3 3 ϕ p D p∗ε ϕ p∗D p∗ε 150∗(1−ε )∗μ∗v 1.75∗ρ∗v 2 + =( ρ p −ρ )∗g 2 2 3 3 ϕ p D p∗ε ϕ p∗D p∗ε The fluidized bed will blow away when the velocity of the particle reaches the terminal velocity . Material balance before∧after of the fluidization m sbefore =m s after ρ p∗(1− ε0 )∗L0∗ A= ρ p∗(1− ε )∗L∗A 1− ε0 L = L0 1− ε

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Minimum fluidization velocity (v mf ) 2 150∗(1− εmf )∗μ∗v mf 1.75∗ρ∗v mf + =( ρ p −ρ )∗g 2 2 3 3 ϕ p D p∗εmf ϕ p∗D p∗εmf Porosity at minimum fluidization veocity ( εmf ) Correlation of Wen∧Yu 1/ 3 0.071 ε mf = ϕ 0.091∗(1− εmf ) ε3mf = ϕ2 For values of εmf