Simulation of nonisothermal pressure swing adsorption.

Chihara, Kazuyuki; Suzuki, Motoyuki

doi:10.1252/jcej.16.53

Cited by 77 publications

(48 citation statements)

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“…The thermal effects of adsorption have already been studied for pressure swing adsorption for gas-mixture separation using the Equilibrium Ž . Theory Farooq and Ruthven, 1990 , the linear driving force Ž approximation Chihara and Suzuki, 1983;Farooq et al, 1988; . Kikinides and Yang, 1993 and taking into account intraparti-Ž .…”

Section: Introductionmentioning

confidence: 99%

Improvement of hydrogen storage by adsorption using 2‐D modeling of heat effects

et al. 2002

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Section: Introductionmentioning

confidence: 99%

Improvement of hydrogen storage by adsorption using 2‐D modeling of heat effects

et al. 2002

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“…Fernandez and Kenney (1983), Chan et al (1981),Chengand Hill (1983, Nataraj and Wankat (1982) for PSA, and by Turnock and Kadlec (1971) for a single-column PSA process. For the air-drying PSA process, the models by Chihara and Suzuki (1983), and Carter and Wyszynski (1983) have accounted for the mass transfer rates in porous sorbent by using the linear driving force approximation. All of these models with the exceptions of Turnock/Kadlec and FernandezIKenney deal with dilute mixtures; hence linear isotherms are used.…”

Section: Introductionmentioning

confidence: 99%

Bulk separation of multicomponent gas mixtures by pressure swing adsorption: Pore/surface diffusion and equilibrium models

1986

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A theoretical and experimental study is performed for the bulk separation of a ternary mixture by pressure swing adsorption. Three concentrated products can be obtained by cycling the pressure in the adsorber. Three models are formulated for the cyclic process: equilibrium, Knudsen diffusion, and Knudsen plus surface diffusion. The latter model provides the best results when compared with the experimental data, due to the important contribution of surface flux to the total flux in the sorbent pores. SCOPEAn increasing number of commercial applications are being discovered for pressure swing adsorption (PSA) because of its low energy requirements and costs. The applications are, however, somewhat limited to gas purification processes, with the only bulk separation being for 0, or N, from air. Multicomponent bulk separation by PSA using one sorbent and a single PSA unit, despite its promising commercial value, has not appeared in the literature. In this study, an H,/CH,/ CO, mixture (one-third each by volume) is separated by PSA using activated carbon and involving five basic cyclic steps: I repressurization, I 1 adsorption, 111 cocurrent depressurization, IV countercurrent blowdown, and V purge. Following the order of increasing adsorption strength, H, is produced in step II and in the early stage of step 111. The later cut in step 111 yields CH,, and steps IV and V produce CO, . A basic understanding of the cyclic process is obtained by modeling. Three models are formulated and compared with experimental results: equilibrium model, Knudsen diffusion model, and Knudsen plus surface diffusion model. CONCLUSIONS AND SIGNIFICANCEBulk separation of the ternary mixture H,/CH,/CO, is accomplished by PSA using a single sorbent. Highpurity products of H, and CH, are obtained, whereas the product purity for CO, only reaches 60% due to the low selectivity between CO, I CH, on activated carbon. Of the three models for the cyclic process, the Knudsen plus surface diffusion model provides the best results when compared to the experimental data. Due to the high surface coverage, surface diffusion significantly contributes to the total flux in the sorbent pores, generally over 50% in the PSA process. Accounting for the strong dependence of surface diffusivity on surface coverage, the effects of purge/feed ratio, pressure ratio, feed rate, and end pressure of depressurization on the separation are predictable by the model. A basic understanding of the bed dynamics also is presented.

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“…The parameter ksav, particle mass transfer coefficient, is usually related to the intraparticle diffusivity, Ds, and to the radius of an adsorbent particle, R, through the following equation4): ksav= l5Ds/R2 (1) Equation (1) was derived for long-term adsorption/ desorption from a uniform initial concentration distribution. In cases of rapid adsorption cycles, such as pressure swing adsorption, however, application of the particle mass transfer coefficient defined by Eq.…”

Section: Introductionmentioning

confidence: 99%

Mass transfer coefficient in cyclic adsorption and desorption.

Nakao

Suzuki

1983

J. Chem. Eng. Japan

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125

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Intraparticle distribution of adsorbate amount in cyclic adsorption and desorption is simulated by two methods: rigorous numerical solution of the particle-phase diffusion equation and the linear driving force (LDF) approximation. It becomes clear that the conventional value of 15 DJR2as the intraparticle mass transfer coefficient, ksav, in the LDFmethod is not advisable for the simulation of transient adsorption and desorption. A mass transfer coefficient defined by including the cycle time is thus proposed. In this new conception, ksav increases with decreasing cycle time and approaches n2DJR2with increasing cycle time. Simulations of cyclic modeby the LDFmethod using this newksav agree well in the steady state with that obtained by numerical solution of the diffusion equation. In unsteady-state operation, however, the two simulations do not coincide with each other because of overestimation of driving force for adsorption and underestimation for desorption in the LDFmethod.

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Simulation of nonisothermal pressure swing adsorption.

Cited by 77 publications

References 0 publications

Improvement of hydrogen storage by adsorption using 2‐D modeling of heat effects

Improvement of hydrogen storage by adsorption using 2‐D modeling of heat effects

Bulk separation of multicomponent gas mixtures by pressure swing adsorption: Pore/surface diffusion and equilibrium models

Mass transfer coefficient in cyclic adsorption and desorption.

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