Process for the removal of volatile organic compounds from a fluid stream
AssigneeUop LLC
InventorsAndrew S. Zarchy, Kirit M. Patel
Life of this patent
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Abstract
A process claimed for the removal of VOCs from fluid streams. The process comprises a vacuum swing adsorption zone containing at least 2 adsorption beds wherein the adsorbent beds are cocurrently purged with a diluent stream comprising an inert gas prior to a countercurrent evacuation step. In addition, the adsorbent beds may contain a first adsorption layer comprising an adsorbent selective for the adsorption of the inert gas, whereby the inert gas is retained within the VSA system to prevent the creation of an explosive mixture upon the condensation of the desorbed VOCs.
Claims25
A vacuum swing adsorption (VSA) process for the separation and recovery of VOCs from a feedstream comprising VOCs and mixtures thereof with air, said process comprising the following steps:
- a) passing an adsorbable inactive gas stream to a first adsorption bed of a VSA zone comprising at least two adsorption beds each of said adsorption beds containing an adsorbent selective for the adsorption of said VOCs to preload said first adsorption bed with said adsorbable inactive gas and withdrawing a first adsorption effluent stream;
- b) countercurrently evacuating said first adsorption bed to a desorption pressure to provide a first residual gas stream comprising said adsorbable inactive gas;
- c) passing said feedstream to said first adsorption bed at adsorption conditions including an adsorption pressure and an adsorption temperature and recovering a second adsorption effluent stream;
- d) cocurrently passing a portion of the first or a second residual gas stream in a copurge step to said first adsorption bed and producing a third adsorption effluent stream;
- e) admixing said third adsorption effluent stream and said second adsorption effluent stream to provide a treated adsorption effluent stream depleted in VOCs relative to the feedstream;
- f) countercurrently evacuating said first adsorption bed to said desorption pressure to provide a tail gas stream comprising said VOCs and separating said tail gas stream into a VOC-containing stream and the second residual stream;
- and
- g) repeating steps (c) through (f) with each of said adsorption beds such that a continuous operation of the process is performed.
A vacuum swing adsorption (VSA) process for the separation and recovery of VOCs from a feedstream comprising VOCs, and a mixture thereof with air, said VSA process comprising the following steps:
- a) passing a gas stream comprising nitrogen to a first adsorption bed of a VSA zone comprising at least two adsorption beds, each of said adsorption beds containing a first adsorbent layer and a second adsorbent layer, said first adsorbent layer comprising an adsorbent selective for the adsorption of VOCs, said second adsorbent layer comprising an adsorbent selective for the adsorption of nitrogen, to preload said first adsorbent bed with nitrogen and withdrawing a first adsorption effluent;
- b) countercurrently evacuating said first adsorption bed to a desorption pressure to provide a first residual gas stream comprising nitrogen;
- c) passing said feedstream at adsorption conditions including an adsorption temperature and an adsorption pressure to said first adsorption bed and withdrawing a second adsorption effluent stream depleted in VOCs;
- d) cocurrently passing a portion of the first or a second residual gas stream to said first adsorption bed and withdrawing a third adsorption effluent comprising oxygen;
- e) admixing said third adsorption effluent stream and said second adsorption effluent stream to provide a treated adsorption effluent stream having a reduced concentration of VOCs;
- f) countercurrently evacuating said first adsorption bed to the desorption pressure to provide a tail gas stream comprising nitrogen and VOCs;
- g) separating said tail gas into a VOC-containing stream and the second residual gas stream;
- and
- h) repeating steps (c) through step (g) such that a continuous operation of said process is performed.
Dependencies are inferred from the claim text.