| 摘要 |
An improved process and apparatus 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 so that 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 flow pattern of the inlet air-hydrocarbon vapor mixture and the bed of solid adsorbent being regenerated are periodically changed so that when the bed through which the inlet air-hydrocarbon mixture is flowing becomes loaded with adsorbed hydrocarbons, the inlet air-hydrocarbon mixture is caused to flow through the bed which has just been regenerated. The regeneration of the beds is accomplished by evacuating the beds with vacuum pumping so that a major portion of the hydrocarbons are desorbed therefrom and subsequently introducing a small quantity of heated hydrocarbon-free air into the beds so that additional hydrocarbons are stripped therefrom. The air-hydrocarbon vapor mixture produced in the regeneration of the beds is contacted with a heated first portion and a second portion of a liquid absorbent so that a major portion of the hydrocarbons are absorbed therefrom and recovered. The first portion is heated by passing it in heat exchange relationship with a seal liquid used in a vacuum pump which effects the vacuum pumping of the adsorbent beds. Apparatus for carrying out the process of the invention is also provided.
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