TRANSVERSE DISPERSION IN GRANULAR BEDS .2. MASS-TRANSFER FROM LARGE SPHERES IMMERSED IN FIXED OR FLUIDIZED-BEDS OF SMALL INERT PARTICLES

• Type: Article in International Scientific Journal
• Date: 1988

Authors

coelho, man (Author) FEUP; decarvalho, jrfg (Author) Other

Journal

Title: Chemical Engineering Research and Design

Vol. 66

Pages: 178-189

ISSN: 0263-8762

Publisher: Institute of Chemical Engineers

Indexing

ISI Web of Knowledge - 24 Citations

Scopus - 21 Citations

Other information

Authenticus ID: P-001-TGR

Abstract (EN): A theoretical and experimental study is described of the problem of mass transfer between a large 'active' sphere and the fluid flowing around it in the interstices of a fixed or fluidised bed of small inert particles. A continuum approach is adopted to describe the flowfield in the granular bed and a potential flow solution is obtained, from the coupling of D'Arcy's law and continuity. Description of the flowfield is then coupled with the equation of conservation of the transferred species; particular attention is given to the possibility of convective dispersion taking over molecular diffusion in the granular bed. An analytical solution of the mass transfer equation is developed for the condition of thin concentration boundary layer and a numerical solution is worked out. Experimental data for the sublimation of naphthalene are reported for fixed and fluidised beds over a wide range of the experimental variables. Application of the theory to the prediction of pressure effects on the rate of combustion of coke particles in fluidised beds is presented.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12