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Multiple solvent delivery system

  • US 5,360,320 A
  • Filed: 02/27/1992
  • Issued: 11/01/1994
  • Est. Priority Date: 02/27/1992
  • Status: Expired due to Term
First Claim
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1. A supercritical fluid extraction system, comprising:

  • a supercritical fluid extraction means;

    multi-solvent delivery means for supplying a gradient of comparable solvents at a controlled pressure and converting to a pressure vessel communicating with said supercritical fluid extraction means;

    said multi-solvent delivery means for supplying including;

    a source of a first solvent;

    first means for pumping the first solvent through a first pump outlet into a first conduit;

    a second solvent;

    second means for pumping the second solvent through a second outlet into a second conduit;

    first transducer means for measuring the pressure in said first conduit and generating a first signal proportional to the pressure and for measuring the pressure in said second conduit and generating a second signal proportional to the pressure;

    mixer means communicating with said first and second conduits for mixing said first and second solvents and applying the mixed solvent solution to said supercritical fluid extraction system;

    programmed means for generating third and fourth electrical signals representing programmed concentration of said first and second solvents respectively in said mixed solvent solution applied to said supercritical fluid extraction system;

    means for generating a fifth signal representing a programmed pressure;

    means for multiplying said first signal by said third signal, wherein a sixth signal proportional to said pressure in said first conduit multiplied by the programmed concentration of the first solvent in the mixed solvent solution is generated;

    means for multiplying said second signal by said fourth signal, wherein a seventh signal proportional to the programmed concentration of said second solvent in the mixed solvent solution multiplied by said pressure in said second conduit is generated;

    means for adding said sixth and seventh signals;

    feedback comparison means for comparing the sum of said sixth and seventh signals with said signal representing the programmed pressure to generate an error signal;

    means for multiplying said error signal by said third signal and supplying it to said first means for pumping to control said pumping rate wherein the pumping rate of the said first means is maintained in programmed concentration proportion to the flow rate at a pressure equal to said programmed pressure; and

    means for multiplying the error signal by said fourth signal to generate a signal for controlling said second means for pumping, wherein the second means for pumping pumps at a rate of programmed concentration proportion to the flow rate at the programmed pressure, whereby said mixture of solvents is controlled at a programmed concentration of solvents at a programmed pressure.

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