Transport of a fluid through a packed bed

The transport of a fluid through a packed bed can be interpreted on the basis of a dispersion model in terms of a dimensionless dispersion number and an effective adsorption capacity for the adsorbent-fluid system. The dimensionless dispersion number is inversely related to the theoretical plate number in the theoretical plate model for the transport of a fluid through a packed bed. The effects of neglecting one of the terms in the solution to the transport equation in the theoretical plate treatment has been examined from the viewpoint of the dispersion model and shown to be significant for adsorbent-fluid systems with dispersion numbers that correspond to low and even fractional theoretical plate numbers. Even for systems with low dispersion numbers that correspond to high theoretical plate numbers, the error is not negligible for values of the concentration of the adsorbate at the outlet of a packed bed that are small compared with the inlet concentration. Experimental data for adsorption systems with dispersion numbers that correspond to small and fractional theoretical plate numbers are compared with the time-dependent equations of the dispersion and theoretical plate models for the transmission of an adsorbate through a packed bed, where the transmission is the ratio of the adsorbate concentration at the outlet of the bed to that at the inlet.