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Vacuum swing adsorption process for separating propylene from propane

  • US 6,296,688 B1
  • Filed: 11/30/1999
  • Issued: 10/02/2001
  • Est. Priority Date: 11/30/1999
  • Status: Expired due to Fees
First Claim
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1. A vacuum swing adsorption process For the separation of propylene from a feedstream comprising propylene and propane to produce a high purity propylene product, said process comprising:

  • a) passing the feedstream at effective adsorption conditions in an adsorption step to a first adsorption bed of a plurality of adsorption beds, each of said adsorption beds containing a selective adsorbent comprising AlPO-14 to produce a raffinate stream, comprising propane;

    b) terminating the passing of the feedstream to the first adsorption bed and co-currently purging the first adsorption bed at a co-purge pressure essentially equal to an adsorption pressure with a recycle stream to provide a purge gas stream comprising propane;

    c) co-currently venting the first adsorption bed to a vent pressure and withdrawing a vent stream;

    d) co-currently depressurizing the first adsorption bed to a provide-purge pressure lower than the vent pressure to produce a provide-purge gas and passing the provide-purge gas to another adsorption bed;

    e) further co-currently depressurizing the first adsorption bed in a first equalization step to an equalization pressure lower than the provide-purge pressure to produce an equalization gas and passing the equalization gas to another adsorption bed;

    f) counter-currently depressurizing the first adsorption bed in an evacuation step to a desorption pressure to provide a first desorption stream comprising propylene;

    g) counter-currently purging the first adsorption bed with a vacuum purge gas stream from another adsorption bed to produce a second desorption stream comprising propylene;

    h) counter-currently repressurizing the first adsorption bed in a second equalization step to about the equalization pressure;

    i) further counter-currently repressurizing the first adsorption bed to about the adsorption pressure with at least a portion of the raffinate stream;

    j) compressing the first desorption stream and the second desorption stream to provide the high purity propylene product;

    k) recycling at least a portion of the high purity propylene product to provide the recycle stream; and

    l) repeating steps (a) to (k) for each of the adsorption beds to provide a continuous process.

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