(544c) Thermal Management of Structured Adsorbents in Gas Separation Processes

In order to have an efficient adsorptive separation, structured adsorbents are expected to satisfy not only mass transfer and pressure drop considerations, but also the thermal management requirements as well. In the case of pellets having a size more than several micrometers there is a temperature gradient between the surface and the inner part of the particle when adsorption is preceded. Therefore one can not obtain a uniform temperature across the particle. The story is different in the case of monoliths, foams and laminates in which the macropore wall structure allows the dissipation of heat and consequently a uniform temperature distribution across the adsorbent. These features are particularly significant in PSA devices wherein isothermal conditions need to be maintained. Operating at adiabatic conditions creates thermal variations in the bed and deteriorates the performance.

Therefore, it is a crucial need for the design of advanced gas separation processes to take into account the heat transfer characteristics of adsorbents. To what extent the structure of adsorbent affects the thermal behaviour of the system is a question which would be addressed in this paper. In order to assess the performance of alternate adsorbents, a variety of numerical models are developed to predict their thermal behaviour and, in particular, to examine their performance in terms of gas separation efficiency and product purity. The results from these mathematical models are used to guide future experimental work.