Patent GB-718523-A (GB)
Title: Improvements in or relating to adsorbent reactivation processes
IPC: C01B31/08
Filed: 1951-11-16
Abstract: <PICT:0718523/III/1> In a process for the reactivation of a deactivated solid adsorbent which has been subjected to an adsorption-desorption cycle and which is contaminated with deactivants which process is of the type wherein the adsorbent is subjected to progressively increasing temperatures by passage successively through a first low temperature reactivation zone, a second medium temperature reactivation zone and a third high temperature reactivation zone and in which a major portion of the adsorbent is removed from the medium temperature zone without passage through the high temperature zone, the minor portion of the adsorbent passing through the high temperature zone, deactivants freed from the adsorbent in the high or medium temperature zones are prevented at least in part from passing into a reactivation zone operating at a lower temperature than the zone in which the deactivants in question were freed.  As shown in the drawing, deactivated adsorbent, such as char enters the reactivation vessel 1 at the top and passes successively through superposed beds arranged on perforated plates 2 through which a fluidizing gas passes upwardly.  Progressively increasing temperatures, as indicated, prevail from the top to the bottom of the reactivation vessel and char passes through downcomers 3 from one bed to the next below. Pipe 9 is provided at an intermediate bed to withdraw the major portion of the char, e.g. 60 to 80 weight per cent., the remainder of the char passing to the lowermost bed and being withdrawn therefrom by pipe 12 to rejoin that withdrawn from pipe 9 in line 14.  In order to prevent internal recycling of desorbed deactivants, solid plates 20 and/or 16 are provided, and draw-off lines 18 and 11 withdraw the gases from below these plates; further pipes 19 and 15 are provided above the respective plates for the entry of steam or reactivation gas.  Thus high temperature flue gas at 2,000 to 2,500 DEG F. enters at 4 and the combustion gases together with the deactivants are withdrawn at 18 below plate 20 and replaced by steam from pipe 19 above plate 20. These in turn are withdrawn at 11 and replaced by further gas at 15 above plate 16.  In a modification only lower and high temperature reactivation zones are provided, the major portion of the adsorbent being withdrawn after passage through the lower temperature zone. The process is particularly applicable to reactivation of charcoal employed in an adsorption-desorption system for the separation by fractionation of C1 to C3 hydrocarbons contained in admixture with higher molecular weight hydrocarbons.  Reactivator heating may also be effected indirectly, with heating coils 17 in one or more stages and steam used as the reactivation gas.  More than one adsorbent side stream may be withdrawn from more than one intermediate stage and the tower diameter may be varied to parallel adsorbent and vapour rates in the adsorber.  The process may be carried out employing the adsorbent in the fluidized state using bubble plates, perforated plates, packing or baffles, or a soaking type operation may be employed in which the adsorbent gravitates slowly downwards as a solid bed.