Brandani, Federico

Brandani, Stefano

Mangano, Enzo

Pullumbi, Pluton

English

The mass transfer coefficient is a fundamental property needed to design adsorption gas separations. A collaborative study is presented where commercial LiLSX beads used in air vacuum swing adsorption for the production of oxygen are tested in two volumetric apparatuses. The initial results based on the software available in the commercial system seemed to point to a surface barrier model for the adsorption kinetics of nitrogen, but this system is known to be macropore diffusion controlled. A detailed model of the system and a new way of representing the experimental data are used to show that the mass transfer kinetics is clearly a diffusion process. Guidelines and recommendations on which tests are needed to ensure the correct use of a volumetric system in this case are presented. Through the correct interpretation of the flow through the valve in the two volumetric apparatuses, consistency in the mass transfer time constant is achieved. The effect of using the correct diffusion time constant vs the one obtained using the traditional approach is demonstrated comparing a typical oxygen vacuum swing adsorption process. A drop in performance of nearly 15% in both productivity and energy consumption is predicted if the incorrect diffusion time constant is used

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Using a volumetric apparatus to identify and measure the mass transfer resistance in commercial adsorbents

https://www.pure.ed.ac.uk/ws/files/78418262/Volumetric_Diffusion_N2_LiLSX_Paper_accepted.pdf

Using a volumetric apparatus to identify and measure the mass transfer resistance in commercial adsorbents

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