Process for treating liquid streams to remove unwanted impurities

A method of treating a liquid stream which contains impurities in limited amounts with a solid adsorbent having an affinity for the impurities compared with other components in the liquid to reduce the impurities significantly for the adsorber-treated product with the following steps:

• providing a liquid fresh feedstream to an adsorber suitably cooled and suitably free from agents which might degrade the impurity removal performance after long term regeneration;
• providing a porous, particulate adsorbent within a 8 to 48 Tyler mesh range and in a suitably narrow fraction such that size segregation is acceptable when subject to fluidization with bed expansions no greater than 10 percent with the liquid feedstream or liquid effluent from preceding adsorption stages;
• providing an adsorption section consisting of liquid fluidized stages with a bottom inlet and an upper outlet in the adsorber vessel and the same if more than one adsorber vessel;
• introducing an adsorbent stream into an upper part of a last adsorption stage to countercurrent contact the said liquid stream that flows upward from a preceding adsorption stage until the said liquid fresh feedstream enters a fresh feed adsorption stage;
• withdrawing spent adsorbent as a slurry near an inlet distributor of the fresh feed adsorption stage to proceed to a liquid-solid separator that separates liquid forming the slurry for return as liquid to the adsorption feed stage, whereas the solids separated enter a regeneration section that has at least two desorption zones and a cool-down zone for the regeneration of the spent adsorbent stream;
• providing the regeneration section with two or more desorption zones which first continuously desorb a significant portion of the desired liquid product initially in spent adsorbent pores of the adsorbent by recirculating gas after cooling and condensing most of the liquid released, with impurity concentration lower than that of the fresh feed, by stripping and heating with this recirculated gas with suitable makeup gas to a higher temperature than the solids leaving a recycle liquid desorption zone, but significantly lower in temperature than that used for heated gas that enters a final desorption zone and which sufficiently removes the impurities from the solids as a concentrated impurity stream;
• introducing desorbed adsorbents from the final desorption zone into the cool-down zone of the regenerator;
• introducing a reactivating gas sufficiently free from any agents that might interfere with the desired adsorption of impurities to accomplish cool-down of the absorbent solids leaving the final desorption zone with cross flow contact using a plurality of countercurrent contacts to hot regenerated adsorbent leaving the final impurity stage downwardly flowing for the transfer of heat to the reactivating gas leaving the regeneration section;
• causing said heated gas to enter a heater for heating to the required temperature to accomplish sufficiently the desorption of impurities in the final desorption zone on a once through basis;
• providing a regenerated adsorbent stream from said cool-down zone with sufficient cooling to remove the heat of wetting, preferably as a slurry with the final desorption liquid before introducing into the adsorber section;
• and
• recirculating the cooled regenerated adsorbent stream for introduction into said adsorption section.