Numerical simulation of a PSA system using a pore diffusion model

Raghavan, N.S.; Hassan, M.M.; Ruthven, Douglas M.

doi:10.1016/0009-2509(86)80010-0

Cited by 90 publications

(48 citation statements)

References 11 publications

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“…If mass transfer between solid and gas phases during the pressurization and the blowdown steps is assumed to be negligible, then at cyclic steady state the amount adsorbed during the adsorption step should be equal to the amount desorbed during the purge step. Transient PSA simulation with a frozen solid approximation during pressurization and blowdown has been validated for processes of purification (Chihara and Suzuki, 1983a,b;Raghavan et al, 1985;Hassan et al, 1985) and kinetically controlled bulk separation (Hassan et al, 1986(Hassan et al, , 1987. Therefore, for these processes, Skarstrom PSA operation at cyclic steady state can be viewed as a continuous countercurrent flow (CCF) system in which the immobile solid phase adsorbs from the high-pressure stream and releases to the low-pressure purge stream with zero net accumulation in the solid phase, Figure 1 b.…”

mentioning

confidence: 99%

Continuous countercurrent flow model for a bulk PSA separation process

Farooq

Ruthven

1990

AIChE Journal

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The steps involved in a basic Skarstrom pressure swing adsorption (PSA) cycle are pressurization, high-pressure adsorption, countercurrent blowdown, and countercurrent purge, as represented in Figure la. If mass transfer between solid and gas phases during the pressurization and the blowdown steps is assumed to be negligible, then at cyclic steady state the amount adsorbed during the adsorption step should be equal to the amount desorbed during the purge step. Transient PSA simulation with a frozen solid approximation during pressurization and blowdown has been validated for processes of purification (Chihara and Suzuki, 1983a,b;Raghavan et al., 1985;Hassan et al., 1985) and kinetically controlled bulk separation (Hassan et al., 1986(Hassan et al., , 1987. Therefore, for these processes, Skarstrom PSA operation at cyclic steady state can be viewed as a continuous countercurrent flow (CCF) system in which the immobile solid phase adsorbs from the high-pressure stream and releases to the low-pressure purge stream with zero net accumulation in the solid phase, Figure 1 b. Suzuki (1985) developed a C C F model for a trace component PSA system and showed that the resultant steady-state concentration profiles match with those from the transient simulation using a frozen solid approximation during pressurization and blowdown and a small throughput ratio so that solid-and gasphase profiles also remain nearly frozen during the adsorption and the desorption steps. While these extreme assumptions may be realistic for a purification process, in a bulk separation process there generally will be significant excursions of the concentration profiles during the adsorption and the desorption steps. The purpose of this communication is to examine the usefulness of the CCF model for a bulk PSA separation process. Theoretical ModelWe consider an isothermal, plug flow system in which frictional pressure drop in the bed is negligible and the total pressure in the bed remains constant during the adsorption and the desorption steps. The equations are developed for a two-compo-

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confidence: 99%

Continuous countercurrent flow model for a bulk PSA separation process

Farooq

Ruthven

1990

AIChE Journal

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“…As a test system to compare the efficiency of the new numerical method on a sufficiently large problem, we consider the heatless drier model of Raghavan et al (1986). The emphasis here is not on modifying or improving the mathematical model but on comparing simulation times for both dynamic and direct CSS calculations between an equally spaced dense grid (one-domain method) and the proposed two-domain method with 4 + 1 elements.…”

Section: Simulation Of a Heatless Drier Psa Processmentioning

confidence: 99%

“…The emphasis here is not on modifying or improving the mathematical model but on comparing simulation times for both dynamic and direct CSS calculations between an equally spaced dense grid (one-domain method) and the proposed two-domain method with 4 + 1 elements. The process is a standard 4 step PSA system and the model of Raghavan et al (1986) is based on the following general assumptions:…”

Section: Simulation Of a Heatless Drier Psa Processmentioning

confidence: 99%

A New Numerical Method for Accurate Simulation of Fast Cyclic Adsorption Processes

Ahn

Brandani

2005

Adsorption

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In the simulation of fast cyclic adsorption processes, to apply the Fickian diffusion model it is necessary to include an increasing number of numerical discretization points as the cycle time is reduced in comparison to the characteristic diffusional time constant.We propose a new numerical method based on the definition of two distinct regions within an adsorbent particle: an outer layer where the concentration varies significantly with large internal gradients leading to enhanced mass fluxes, and an internal region where the concentration profile is virtually flat. The proposed method leads to the automated generation of a numerical grid that has a constant number of elements independent of the process cycle time. The procedure is demonstrated on a model for the simulation of a heatless dryer pressure swing adsorption process.

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“…Under optimum conditions, over 28 bed volume of feed water can be treated by the resin bed bringing down the furfural concentration from 500 ppm to less than 10 ppm. The breakthrough curves obtained in the adsorption cycle with both columns have been simulated by a mathematical model for isothermal adsorption for trace system as given by Raghavan [7] and modified for use with Langmuir isotherm model. The model equations in dimensionless form are given as follows.…”

Section: Adsorption Cycle Experimentsmentioning

confidence: 99%

Process studies for development of adsorption technology for furfural recovery from waste water

Nanoti¹,

Gupta²,

Dasgupta³

et al. 2008

Environ. Prog.

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Lube refineries in India are facing pollution problems associated with the occasional loss of furfural from their solvent recovery column bottoms in the extraction plant, which constitute both an economic loss and an environmental hazard. Although earlier studies on furfural removal by adsorption on polymeric resins concentrated on equilibrium and kinetic/breakthrough measurements in small diameter columns in the adsorption, the regeneration of the loaded resin adsorbent has not been given adequate attention. This paper focuses on these issues and also includes studies on larger diameter columns with a view to provide data for design of a pilot scale plant for furfural recovery to be set up in a lube complex. The experimental data from adsorption cycle studies indicate that the resin bed is able to treat 28 bed volumes of furfural laden water bringing down the furfural concentration from 500 ppm to less than 10 ppm. The regeneration data indicate the recovery scheme produces an aqueous stream which contains 3% furfural which has to be taken back to the solvent recovery column in the extraction complex. Adsorption and regeneration data have been simulated respectively by the LDF and diffuse wave model.

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Numerical simulation of a PSA system using a pore diffusion model

Cited by 90 publications

References 11 publications

Continuous countercurrent flow model for a bulk PSA separation process

Continuous countercurrent flow model for a bulk PSA separation process

A New Numerical Method for Accurate Simulation of Fast Cyclic Adsorption Processes

Process studies for development of adsorption technology for furfural recovery from waste water

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