A Primer on Gas-Solids Fluidization

• Published in: Chemical Engineering Vol. 119; no. 8; pp. 38 - 47
• Main Authors: Dhodapkar, Shrikant, Zaltash, Abdolreza, Klinzing, George
• Format: Magazine Article Trade Publication Article
• Language: English
• Published: New York Access Intelligence LLC 01.08.2012
• Subjects: Bubbles; Catalytic cracking; Chemical engineering; Chemical process industries; Cross sections; Flow velocity; Fluid dynamics; Fluid flow; Fluidized bed boilers; Fluidizing; Mathematical analysis; Pressure drop; Velocity; United States > US
• ISSN: 0009-2460; 1945-368X

During the past five decades, fluidization technology has been extensively applied to various chemical processes. It provides better heat and mass transfer between the fluid and the solid compared to conventional packed- or moving-bed unit operations. This article summarizes the basic concepts of fluidized-bed technology and provides a useful collection of equations for gas-solids systems. Minimum fluidization velocity is the transition velocity at which packed-bed behavior changes to fluidized-bed behavior. It corresponds to the condition where the weight of the bed per unit cross-sectional area is equal to the pressure drop across it. The pressure drop increases linearly with gas velocity in a packed bed until the total drag force on the bed starts to approach the weight of the bed. For gas-solid flow, various flow-regime maps have been proposed using combinations of gas velocity, pressure drop, voidage, slip velocity, solids loading, Froude number and Reynolds number.