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Measurement of diffusion in the “ash layer” in gas—solid reactions

✍ Scribed by A.N. Gokarn; L.K. Doraiswamy

Publisher
Elsevier Science
Year
1972
Tongue
English
Weight
608 KB
Volume
27
Category
Article
ISSN
0009-2509

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✦ Synopsis

A diffusion cell has been developed to measure the effective diEusivity of gases through a porous solid, formed either by compressing powder in situ or separately during the reaction of a gas with solid in the form of a pellet. Based on the experimental observations made with this cell, it has been shown that the effective diffusivities of pellets having the Fame porosity but with different histories differ quite markedly. Pellets formed from powder by compression have an effective difisivity lower than that for pellets of the same porosity but formed during reaction. The appropriate way to measure the effective dfisivity of the product crust, i.e. the "ash layer" in the case of gas-solid reactions (following the moving boundary model), is to shape the product crust to the required shape and then measure its effective diffusivity.

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