Method and apparatus for desolvating flowing liquid

摘要

Methods and apparatus for desolvating flowing liquid streams while retaining temporal resolution of dissolved substrates are disclosed. A novel small-scale self-regulating spray dryer preserves temporal resolution while desolvating a liquid chromatography eluent stream and depositing the solute onto an optical surface for infrared spectrographic analysis. The liquid eluent is pumped through a heated nebulizer to create a high-speed jet of solute containing liquid and solvent vapor. This jet is directed circumferentially inside a hot cylindrical cavity. Centrifugal force causes the larger liquid droplets to travel along the outer diameter of the cavity. The cavity surface is heated to cause the droplets to film boil. Film boiling reduces droplet contact with the cavity surface thereby retaining the solute in the droplets. The solute temperature is limited by controlling the pressure into which the solvent evaporates from the droplets. When the droplets are sufficiently small, Stokes drag from the exiting solvent vapor carries the droplets out through the center of the cylindrical cavity. After exiting, the superheated solvent vapor further dries the droplets. Solvent vapor is removed by condensation onto a cooled surface. A freezing point reducing agent may be added to improve removal of solvent condensate. Stokes drag from a non-condensable gas maintains the dried droplets in suspension. This suspension travels through an orifice that focuses the impaction of the dried droplets onto the optical surface for infrared analysis. The deposition surface is in an evacuated chamber and is temperature controlled to freeze liquid solutes yet allowing sublimation of residual solvent.

主权项

1. A method for evaporating liquid from an inlet fluid stream that comprises a predominant proportion of a liquid/solvent component and at least intermittently minor proportions of one of more liquid and/or solid solute components which is/are different from the liquid/solvent component and which have a low volatility relative to the liquid/solvent component, said solute component(s) being dispersed, suspended or dissolved in aerosol droplets of the liquid/solvent component, using an apparatus that comprises in combination:
(a) a chamber having a chamber cavity of generally circular cross section along a chamber axis, said chamber cavity defined in part by a cavity side wall; (b) a source of heat for the cavity side wall that is located outside the chamber cavity in combination with a cavity side wall heat controller set to establish and maintain a solute-concentrator operating temperature, said solute-concentrator operating temperature being a temperature that is at least 20° C. greater than the boiling point of the liquid/solvent component of the fluid stream at the operating pressure inside the chamber cavity, whereby vaporization of the liquid/solvent component creates a gas layer adjacent the heated cavity side wall that substantially prevents aerosol droplet contact with the cavity side wall while a substantial portion of at least one of the solute components is not vaporized; (c) a chamber inlet extending from outside the chamber into the chamber cavity; (d) one or more chamber outlets extending from the chamber cavity to outside the chamber; and, (e) a fluid vortical direction imparting element in or associated with said chamber cavity, the vortical element acting to impart a rotational direction to a fluid stream and selected from the group consisting of: (i) a fluid inlet that directs the fluid stream so as to have a net tangential component relative to the cavity side wall; (ii) a rotating element in said chamber cavity on which the fluid stream impinges and at least a portion of which fluid stream is thereby directed outwards toward the cavity side wall with a net circumferential directional component; (iii) a source of moving gas in said chamber cavity that provides moving gas directed so as to impart motion having a net circumferential component to the fluid stream; and, (iv) a rotational device that rotates the chamber cavity;said method comprising the steps of:
introducing the inlet fluid stream into the chamber cavity; imparting a rotational direction to the inlet fluid stream; maintaining the cavity side wall at a temperature at least 20° C. greater than the boiling point of the liquid/solvent component of the inlet fluid stream; and, producing at at least one of the one or more chamber outlets a concentrated fluid stream in which the concentration of solute is significantly greater than the concentration of solute in the inlet fluid stream.