The performance of molecular sieve adsorption columns: non-isothermal systems

Ruthven, Douglas M.; Garg, Deepak; Crawford, R.M.

doi:10.1016/0009-2509(75)80044-3

Cited by 35 publications

(14 citation statements)

References 15 publications

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“…The fact that the same h value can be used for both adsorption and desorption is worth noting. Determination of the h value by matching experimental temperature breakthrough curves has been discussed by Ruthven et al (1975). Kaguel et al (1985) have shown that the parameter h may be accurately determined from measurements of the thermal wave advancing in an adsorption column.…”

Section: Validity Of the One-dimensional Nonisothermal Modelmentioning

confidence: 98%

Heat effects in adsorption column dynamics. 1. Comparison of one- and two-dimensional models

Farooq¹,

Ruthven²

1990

Ind. Eng. Chem. Res.

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A two-dimensional model that includes radial thermal conduction has been developed to investigate the dispersive effect of heat, including the effect of a radial temperature gradient, on adsorption column dynamics. Such effects can be much greater than axial dispersion. The form of the breakthrough curves can be well represented by the isothermal dispersed plug flow model using an appropriately modified dispersion coefficient. When the natural velocity of the temperature wave is lower than that of the concentration wave, leading to a combined wave front, a simple one-dimensional model with heat transfer to the column wall provides a good prediction of the dynamic behavior. However, when the thermal front leads the concentration wave (pure thermal wave formation), the one-dimensional model overpredicts the dispersion. To obtain an accurate prediction of the dynamic behavior under these conditions requires the use of the two-dimensional model.The effect of the heat of adsorption on the dynamic performance of an adsorption column has been studied by several investigators. Adiabatic sorption has been considered by Leavitt (1962), Carter (1966, 1968a,b), Carter and Barrett (19731, Pan and Basmadjian (1967, 19701, Marcussen (1982, Yoshida and Ruthven (1983), and Raghavan and Ruthven (1984), among others. Although the behavior of large-diameter industrial columns can be adequately simulated by using adiabatic models, a more realistic model including a finite rate of heat loss at the wall is needed to understand the behavior of smaller units. One-dimensional models for such systems have been presented by Ruthven et al. (1975), Sircar et al. (1983), and Kaguei et al. (1985. In these models, the radial temperature gradient is neglected and all resistance to heat transfer is lumped into an overall effective coefficient of wall heat transfer. However, under conditions of finite heat loss at the wall, there must be a significant radial temperature gradient that will, in general, affect the characteristic velocity of the concentration front, thus increasing the dispersion of the mass-transfer zone. Inclusion of radial conduction in the differential heat balance equation can therefore be expected to provide an improved representation of the dispersive effect of heat on the adsorption column dynamics. However, such a two-dimensional model is obviously more complex than the standard one-dimensional dispersion model, and it is therefore pertinent to inquire whether and under what conditions the simpler model can provide an adequate representation of the dynamic behavior. This may be established either by comparing the theoretical response c w e s from the oneand two-dimensional models or by comparison between theory and experiment. The advantage of the former approach, which is followed in this paper, is that the range of process conditions may be more easily varied over a wide range to cover different regimes. The results of such a comparison suggest that under most practical conditions the one-dimensional model provides an ade...

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Section: Validity Of the One-dimensional Nonisothermal Modelmentioning

confidence: 98%

Heat effects in adsorption column dynamics. 1. Comparison of one- and two-dimensional models

Farooq¹,

Ruthven²

1990

Ind. Eng. Chem. Res.

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“…ena through a mathematical model: the former lumped heatand mass-transfer effects into an effective mass-transfer coefficient; the latter missed the subtleties in breakthrough behavior by using a linear isotherm fit. Ruthven et al (1975) developed a simple model to calculate breakthrough curves and corresponding temperature profiles, and then validated it with various hydrocarbons adsorbed on 5A zeolite. Basmadjian (1980a,b) presented graphical methods for predicting the shape of isothermal and adiabatic breakthrough curves, while accounting for intraparticle diffusion.…”

Section: Introductionmentioning

confidence: 99%

Adsorption breakthrough behavior: Unusual effects and possible causes

Park

Knaebel

1992

AIChE Journal

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“…In addition to the steady-state momentum equation, the interpellet conservation of energy has introduced another parameter, the bed-towall heat transfer coefficient h B,W , that needs to be resolved before C m can be found. Ruthven (1984, p. 218) found satisfactory agreement between experimental heat transfer coefficients of Ruthven et al (1975) and those from Leva's correlation for the adsorption of propylene, cis-2-butene and 1-butene from an inert carrier stream in a packed bed of 5A molecular sieve sorbent. For this study it is assumed Leva's correlation is appropriate for the estimation of the bed-towall heat transfer coefficient.…”

Section: U Bmentioning

confidence: 66%

“…Hashimoto and Smith (1974) obtained macro-and micropore diffusion coefficients using moments analysis for the adsorption of 0.5 mol% n-butane from a helium carrier stream over bidisperse alumina pellets. Ruthven et al (1975) assumed isobaric, non-isothermal and plug flow operating conditions using the LDF model to describe micropore diffusion control of propylene, 1-butene and cis-2-butene flowing in an inert carrier stream over 5A zeolite pellets. Andrieu and Smith (1980) obtained micropore diffusion coefficients of carbon dioxide in a packed bed of activated carbon using a moments analysis.…”

Section: Introductionmentioning

confidence: 99%