Sorption of hydrocarbon vapors under dynamic conditions

SORPTION OF HYDROCARBON VAPORS UNDER DYNAMIC CONDITIONS 

The sorption of hydrocarbons proved to be a strongly exothermic process. This is not surprising because both the adsorption (pentane-polystyrene dispersion interactions) and the relaxation of strong inner stresses of the network result in heat generation. The temperature increase of the packing affects the sorption process in two different ways. First, it results in a considerable acceleration of the sorption process due to the facilitated diffusion of the sorbate molecules into the bead interior (the effective diffusion coefficient increases by 1 order of magnitude with the temperature 

New portions of the feed mixture gradually cool down the hot section of the sorbent bed and soon complete its saturation process. The length of the heat wave with a significantly enhanced sorbent temperature amounts to no more than 7—10 cm, even in the case of percolating the concentrated pentane/air mixture. Therefore, only a small portion of the total column experiences the temporary reduction of its adsorption capacity and, at the moment of pentane arrival at the column outlet, the major capacity of the sorbent bed proves to be used up almost completely. The heat evolution is less significant and the capacity loss is much smaller in the case of lower concentrations of pentane in the feed. 

Two important conclusions foUow from these experiments. The first relates to the sorption process with concentrated sorbate in the carrier gas. In this case, the column bed wiU require a special heat exchanger if the sorption capacity of the polymer is expected to be fuUy exploited. Second, a cooling jacket appears to be needed for a safe performance of the sorption 

Tq is the time required for the formation of the constant concentration profile of the sorbate (it is called the loss of protecting time) and K is the protecting time coefficient (the Shilov constant) indicating the protecting time of a layer of unit length. 

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