Process for recovering hydrocarbons with air-hydrocarbon vapor mixtures

摘要

An improved process for recovering hydrocarbons from an air-hydrocarbon vapor mixture such as the mixture of air and vaporized light hydrocarbon compounds expelled as a result of loading gasoline or the like into storage tanks and tank trucks. The air-hydrocarbon vapor mixture is caused to flow through a bed of solid adsorbent whereby the hydrocarbons are removed from the mixture and a residue gas stream comprised of substantially hydrocarbon-free air is produced. The substantially hydrocarbon-free air is vented to the atmosphere and a second bed of solid adsorbent having hydrocarbons adsorbed thereon is subjected to conditions which cause desorption of the hydrocarbons and thereby regeneration of the bed. The regeneration of the beds is accomplished by evacuating the beds with vacuum pumping whereby a major portion of the hydrocarbons are desorbed therefrom, subsequently introducing a small quantity of heated hydrocarbon-free air into the beds whereby additional hydrocarbons are stripped therefrom and then subjecting the bed to further evacuation by ejector jet pumping while continuing to evacuate the bed by vacuum pumping whereby yet additional hydrocarbons are desorbed therefrom. The air-hydrocarbon vapor mixture produced in the regeneration of the beds is contacted with a liquid absorbent whereby a major portion of the hydrocarbons are absorbed therefrom and recovered.