Elasticity of adsorbent beds
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Elasticity of adsorbent beds Mark W. Ackley • Cem E. Celik • Kang Xu Salil U. Rege
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Received: 18 January 2013 / Accepted: 30 April 2013 / Published online: 21 May 2013 Ó Springer Science+Business Media New York 2013
Abstract The practical application of adsorbents with the desired separation properties depends not only upon the adsorption characteristics of the material but also upon the mechanical properties of the packed bed. The packed bed, the vessel surrounding the bed and any internal structure that supports the bed are subjected to both static and cyclic loads during an adsorption process. In order to properly design the vessel and its internal structure, the bulk mechanical properties (most particularly the elastic properties) of the adsorbent bed must be known. The primary focus of this study was to determine the elastic properties of adsorbent beds packed with activated alumina, synthetic molecular sieve 13X or natural zeolite clinoptilolite. The bulk modulus of elasticity was found to be a linear function of applied stress for each of these materials in a range of stresses lower than the bulk crush strength. The Poisson’s ratio for the packed bed was also deduced from these results. Keywords Elastic properties of adsorbent beds Bulk modulus of elasticity Alumina 13X zeolite Clinoptilolite Crush strength
1 Introduction The separation capability of a porous material is of prime concern when considering either purification or bulk separation of gases by means of fixed bed adsorption processes (Ruthven 1984; Yang 1987). A considerable effort is then applied to determine the equilibrium capacity and selectivity of adsorbent materials in order to assess their potential for a desired separation. The practical application of adsorbents with the desired separation properties, however, also depends importantly upon their mechanical properties, i.e. particle properties, as well as bulk properties, of the packed bed (von Gemmingen 1994; Ackley et al. 2012). The packed bed and individual adsorbent particles are subjected to both static and cyclic loads, as are the vessel surrounding the bed and any internal structure that supports the bed. In order to properly design the vessel and its internal structure, the bulk mechanical properties of the adsorbent bed must be known. The elastic properties of the adsorbent bed are of particular interest, and the determination of these properties is the primary subject of this investigation.
2 Background
M. W. Ackley (&) C. E. Celik (&) K. Xu Praxair, Inc, 175 East Park Drive, Tonawanda, NY 14151, USA e-mail: [email protected] C. E. Celik e-mail: [email protected] S. U. Rege Cargill Inc, 9320 Excelsior Blvd. 164-6-9320, Hopkins, MN 55343, USA
The strength of porous adsorbents and catalysts has generally been recognized with regard to resistance to attrition and crushing. Conversely, the elastic properties of the adsorbent particles and the bulk bed have received little attention. Such properties arise in the study of soil compaction and grain storage
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