Patent Publication Number: US-2004050769-A1

Title: Liquid mixture separators

Description:
BACKGROUND AND SUMMARY OF THE INVENTION  
       [0001] The present invention relates to separators for the continuous separation of liquid mixtures.  
       [0002] The invention utilizes differential surface wettability characteristics of solid material particles with respect to two liquids of a liquid mixture. Known technology is utilized relative to fluidization of particles in the separation of liquids of the liquid mixture, which may contain some non-permanent emulsion. Fluidization of particles enables the provision of a dynamic filter device which may operate continuously.  
       [0003] The invention has particular application for the separation of oil-water mixtures, and is applicable to separation of other liquid mixtures.  
       [0004] Certain materials, generally plastics, are oleophilic so that they repel water and have affinity for oil. These include the polyethylenes, polypropylenes, polyamides and polyurethanes. An oil-water separator is known in the art as a coalescer.  
       [0005] Large settling tanks have long been utilized for separation of liquid mixtures, and are often of great size, and require substantial maintenance and operational control.  
       [0006] As known in the art, the wettability of a material by a particular liquid is defined by the contact angle between a drop of the liquid and a plane surface of the particular material on which the drop of the liquid is resting. Respective liquids exhibit varying degrees of wettability with respect to particular materials. Contact angles between the liquid and the material are possible between 0° and 180°. A contact angle of less than 90° is considered to wet the material, and a contact angle of greater than 90° is said not to wet the material. The relevant technology is outlined in U.S. Pat. No. 3,471,018 at column 4, and is discussed in a reference work on surface chemistry, “The Chemistry and Physics of Interfaces”, published by American Chemical Society, Washington, D.C., 1965.  
       [0007] The present invention provides a liquid mixture separator for separating first and second liquids, which comprises a first chamber to contain a liquid mixture, and a second chamber in communication with the first chamber and communicating therewith via a screen wall. A substantial plurality of particles is disposed in the first chamber in contact with the liquid mixture, the particles comprising material which attracts the first liquid and does not attract the second liquid so that the first liquid congregates on the particles. Separated second liquid passes from the first chamber via the screen wall. Outlet means are provided, and comprise separate outlet means for the separated first liquid and the second liquid.  
       [0008] The particles are typically formed of one of polystyrene, polyethylene, polypropylene, or polyamide. The particles are formed of material having appropriate wettability angles.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
     [0009]FIG. 1 is a sectional view of a liquid mixture separator according to the present invention.  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0010] Referring to the drawing, a preferred embodiment of the invention comprises a separation apparatus  10  comprising an inner tube or chamber  12  defined mainly by a generally cylindrical screen housing  14 . A solid cylindrical housing portion  16  is disposed about a lower portion, and a solid cylindrical wall member  18  disposed about the upper portion of the chamber  12  and is spaced from the upper wall of chamber  12 , as shown at  21 , for a purpose hereinafter described. A conical filtering screen  22  is disposed atop chamber  12 .  
     [0011] A pump  24  supplies immiscible liquid-oil mixture via a conduit  26  and a ball check valve  28  which admits and retains the liquid. A large plurality of particles  30  is disposed in chamber  12 , which particles in the present invention are formed of polyethylene plastic. The polyethylene particles are wettable by oil, but not by water. The embodiment herein described is utilized in the separation of oil, as a first liquid, from water, a second liquid. The particles may also be formed of polystyrene, polypropylene, or polyamide.  
     [0012] The solid particles preferably have a density between the densities of the oil and water, and the particle density is close to that of the liquid mixture. The solid particles fluidize because of the density between those of oil and water.  
     [0013] The polyethylene particles are thus wetted by the oil and the water is repulsed. The particles are thus suspended and fluidized by upward flow of the liquid mixture and the particles are suspended by the upper flow of the liquid in the inner chamber.  
     [0014] The oil, because of the lighter phase of lower specific gravity of the mixture, is continuously collected at the top of the chamber, and flows outwardly via the filter  22 , which filter retains the particles in the inner chamber  12  and passes the separated oil, or first liquid, outwardly through an outlet to  34 , formed of polyethylene material wettable only by oil. Upward flow of the oil is aided by operation of a vacuum pump  36 , which provides a relatively low partial vacuum.  
     [0015] The solid wall portion  16  extends about the lower portion of the inner chamber  12  and prevents oil and water mixture and particles from passing outwardly into the lower portion of outer chamber  38 .  
     [0016] The water or second liquid, separated from the oil or first liquid, passes outwardly via fine mesh screen wall  14  which retains the particles in the inner chamber and into an outer chamber  38  which is defined between the screen  14  and walls  16 ,  18  into outer chamber  38  which is defined by solid walls of outer housing  40 .  
     [0017] The oil, or first and lighter phase, is continuously collected at the top of the chamber and passes outwardly from the separator via outlet  34 , and water continuously exits the inner chamber via the screen wall  14  of the inner chamber.  
     [0018] The lower solid wall portion of the inner chamber prevents water in the lower portion of the outer chamber  38  from mixing incoming immiscible liquid mixture in lower portion of the inner chamber.  
     [0019] A drain valve  42  is provided at the bottom portion of the housing  40  to drain the separated water in the outer chamber  38 .  
     [0020] The separator and system are adapted for continuous operation by disposing of the separated second liquid or water via the valve  42  or other appropriate means, and the separated oil or first liquid flows continuously outwardly from the outlet tube  34 . A control valve  44  in a line  46  extending between the upper interior of the outer chamber  38 , and an input pump  24  in line  26 , provide for re-entry of any immiscible liquid in the upper portion of the outer chamber into the input of immiscible fluid via line  26 , if needed.  
     [0021] It will be understood that various changes and modifications may be made from the preferred embodiments discussed above without departing from the scope of the present invention, which is established by the following claims and equivalents thereof.