Abstract:
A fluid separator includes a side-by-side double-vortex fluid generator installed within a pressure vessel. The vortex generator separates the liquid and gas components of the incoming fluid mixture, and the vessel itself helps further separate the liquid into water and oil components, which makes the fluid separator particularly suited for processing fluids extracted from an oil well. The generator includes two diverging vortex tubes each having a polygonal cross-section. Such a cross-section allows the tubes to be formed using a conventional press brake. The vortex tubes also have diverging longitudinal centerlines to help spread the liquid flow pattern discharging into the vessel.

Description:
FIELD OF THE INVENTION 
     The subject invention generally pertains to the separation of gas, oil and water, and more specifically pertains to a vortex-style separator. 
     BACKGROUND OF RELATED ART 
     Forcing a fluid mixture of liquid and gas in a helical flow pattern through a cyclone separator or vortex tube can centrifugally separate the liquid from the gas. In the right applications, this process is effective and widely used. Current methods of centrifugal separation, however, have their limitations and drawbacks. 
     Since the incoming fluid is injected tangentially into the side of a vortex tube, the diameter of the inlet feed pipe is typically smaller than that of the vortex tube. A relatively small diameter inlet pipe creates a flow restriction that can reduce the separator&#39;s flow rate capacity. If a larger diameter vortex tube is used to accommodate a larger inlet pipe, the resulting lower flow velocity and larger helix diameter reduces the centrifugal force and thus reduces the vortex tube&#39;s ability to separate liquid from gas. 
     To overcome this problem, multiple small vortex tubes can be used instead of one large one. Such a solution, however, can lead to an awkward assembly of parts with an excessive amount of interconnecting piping. 
     It can be difficult to design or appropriately size a cyclone separator when the proportions of liquid and gas are unknown or vary widely and sporadically, which is often the case when the incoming fluid is from an oil well. In oil production, the percentages of liquid and gas can range from zero to 100%, which greatly affects the volume rate of flow. Moreover, the specific gravity of the liquid can change depending on the liquid&#39;s proportions of oil and water. 
     Consequently, there is a need for a better liquid/gas separator, particularly for use in the oil industry. 
     SUMMARY OF THE INVENTION 
     It is an object of some embodiments of the present invention to provide a side-by-side double-vortex separator, wherein both vortex tubes share a common inlet pipe. 
     Another object of some embodiments is to use a conventional press brake to form a diverging tube with a polygonal cross-section so that the tube approximates a conical tube. 
     Another object of some embodiments is join two generally conical tubes such that their longitudinal centerlines diverge, whereby the discharge from each tube points in at least a slightly different direction to help create a calmer pool of liquid into which the separated liquid discharges. The calmer pool of liquid promotes the separation of oil and water and helps avoid remixing the liquid with the previously separated gas. 
     Another object of some embodiments is to evenly split the flow through a round inlet pipe so that the split flow is evenly distributed between two vortex tubes. 
     Another object of some embodiments is to withdraw a fluid from an oil well and separate the fluid into three components of water, oil and gas. 
     Another object of some embodiments is to provide a double-vortex separator that can readily handle fluids with a liquid component that can vary in volume between zero and 100%. 
     Another object of some embodiments is to feed a double-vortex generator using an inlet pipe that diverges in diameter to controllably reduce the flow velocity before the incoming fluid enters the vortex tubes. 
     Another object of some embodiments is to provide a side-by-side double-vortex generator that can be readily incorporated into either a vertical or horizontal pressure vessel. 
     Another object of some embodiments is to provide a side-by-side double-vortex generator that can be fabricated of sheet metal or metal plate. 
     One or more of these and/or other objects of the invention are provided by a side-by-side double-vortex fluid separator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  a side view of a fluid separator with its pressure vessel shown in cross-section. 
         FIG. 2  is a front view of the fluid separator of  FIG. 1  with the pressure vessel shown in cross-section. 
         FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 2 . 
         FIG. 4  is an end view similar to  FIG. 3  but looking into the liquid discharge end of the generator. 
         FIG. 5  is an exploded view of the side-by-side double vortex fluid generator used in the separator of  FIGS. 1 and 2 . 
         FIG. 6  is a side view of the generator installed in a horizontal pressure vessel. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1 and 2  illustrate a fluid separator  10  with a double-vortex generator  12  that can separate an incoming fluid  14  into its component parts of water  16 , gas  18  and oil  20 . The proportion of any one component can range from zero to 100% and can fluctuate or change over time. Although separator  10  is particularly suited for processing fluid pumped from an oil well  22 , separator  10  could be applied to other applications. 
     In some embodiments, generator  12  comprises two vortex tubes  24  and  26  with respective fluid inlets  28  and  30  that are fed with fluid  14  via a common inlet pipe  32 . Inlet pipe  32  is connected to an inlet  34  of a vertically elongate pressure vessel  36 . As fluid  14  from inlet pipe  32  enters tubes  24  and  26  tangentially through inlets  28  and  30 , the fluid swirls helically in opposite rotational directions within tubes  24  and  26 . The resulting centrifugal force slings the fluid&#39;s heavier components, oil and/or water, against the inner wall of tubes  24  and  26 . Water  16  and oil  20 , if present, then drain along the inner walls of tubes  24  and  26  toward respective liquid outlets  38  and  40 . The liquid components  42  then empty into a sump  44  at the bottom of vessel  36 , while gas  18  exhausts upward through gas outlets  46  and  48  of tubes  24  and  26  respectively. 
     Due to the differences in specific gravity of water, gas and oil, the three components  16 ,  18  and  20  stratify within vessel  36 . A water extraction line  50 , a gas extraction line  52  and an oil extraction line  54  allow fluids  16 ,  18  and  20  to be drawn out from within vessel  36  and be conveyed to first, second and third locations  56 ,  58  and  60  respectively. Any suitable control/sensor system  55  (schematically illustrated) can be used for sensing oil and water liquid levels and controlling the extraction of those liquids. Examples of control/sensor system  55  are well known to those of ordinary skill in the art. 
     Although the actual construction of generator  12  may vary,  FIGS. 3 ,  4  and  5  show generator  12  preferably comprising a metal fabrication of vortex tubes  24  and  26 , inlet pipe  32 , and a flange plate  62  that provides an annular flange  64  extending radially inward at each of gas outlets  46  and  48 . In cases where some liquid migrates upward along the inner wall of tubes  24  and  26 , flange plate  62  helps prevent the liquid from escaping through gas outlets  46  and  48 . 
     To minimize agitation and mixing of water  16  and oil  20  within sump  44 , fluid  14  is preferably decelerated before reaching liquid outlets  38  and  40 . To do this, vortex tubes  24  and  26  can be made with tapered walls  64  that provide an ever-increasing diameter from gas outlets  46  and  48  to liquid outlets  38  and  40 . In some cases, a diameter  66  at gas outlet  48  is about 4-inches, and a diameter  68  at liquid outlet  40  is about 5-inches for a vortex tube having a length of 60-inches. The selected tube diameters provide a helical flow pattern with a relatively tight radius of curvature. The tight radius promotes liquid/gas separation, and the double-tube design handles greater flow volume without resorting to larger, less effective tube diameters. 
     Although tubes  24  and  26  could be perfectly conical with a perfectly round cross-section, it is advantageous to have a generally polygon cross-section that provides an approximate conical tube. A series of at least five generally flat segments  70 , rather than a smoothly curved surface, is readily manufactured by way of a conventional press brake, provided tubes  24  and  26  are each comprised of two “half pipes.” Brake creases  72  between adjacent segments  70  also provide shallow channels for liquid drainage, thereby perhaps further promoting the separation of liquid and gas. 
     For the illustrated embodiment, vortex tube  24  is comprised of a section  74  joined to a section  76 , and tube  26  is comprised of a section  78  joined to another section  74 ; however, various other sections and corresponding joint locations are well within the scope of the invention. Each section  76  and  78  can be welded or otherwise joined to its respective section  74 , thereby creating a fillet  80  (preferably a weld bead) that extends continuously or intermittently along the tubes&#39; length between the gas and liquid outlets. The term, “fillet,” refers to any element that helps join two adjacent pieces. Examples of a fillet include, but are not limited to, a weld bead (currently preferred), solder, brazing material, adhesive, spot-welded flanges, flanges folded onto themselves, etc. Tubes  24  and  26  are preferably joined to each other by welding, as indicated by weld fillet  80 , or by some other suitable means. 
     Joining vortex tubes  24  and  26  to each other creates a flow splitter  82  between fluid inlet  28  of tube  24  and fluid inlet  30  of tube  26 . Referring to weld fillet  100 , when inlet pipe  32  is welded to tubes  24  and  26 , flow splitter  82  divides a discharge outlet  84  of pipe  32 . As fluid  14  flows through pipe  32 , flow splitter  82  apportions the fluid preferably evenly between vortex tubes  24  and  26 . Inlet pipe  32  can be uniformly cylindrical to provide a generally constant flow velocity, or pipe  32  could be tapered to decelerate the flow before entering vortex tubes  24  and  26 . 
     Referring to  FIG. 2 , since tubes  24  and  26  are tapered and joined along a tangential line  86  of each tube, longitudinal centerlines  88  and  90  of tubes  24  and  26  are tilted out of parallel alignment with each other (i.e., centerlines  88  and  90  are not parallel). 
     To improve the operation of fluid separator  10 , pressure vessel  36  can be provided with a demister  92 , a gas flow deflector  94 , and a flow disruptor  96 . Demister  92  is a body that provides numerous tortuous passageways for gas  18 . Examples of such a body include, but are not limited to, a mass of coarse steel wool, series of fins, matrix of flow obstacles, etc. As gas  18  flows through demister  92 , liquid droplets entrained in the gas tend to cling to various surfaces of demister  92 . As a result, relatively dry gas is conveyed to gas extraction line  52 . 
     Gas flow deflector  94  is a solid plate mounted in proximity with but spaced apart from gas outlets  46  and  48 . Deflector  94  is positioned so as to deflect gas  18  discharged from gas outlets  46  and  48 . Deflecting gas  18  breaks up its flow pattern so that gas  18  flows more evenly across demister  92  as opposed to rushing through one localized area of the demister. 
     Flow disruptor  96  helps breakup strong fluid currents discharged from liquid outlets  38  and  40 . Flow disruptor  96  can be a screen or perforated plate that spans the inner diameter of vessel  36  with the lower end of vortex tubes  24  and  26  protruding through disruptor  96 . To provide flow disruptor  96  with a greater working area, disruptor  96  can be elliptical and installed at an angle, as shown in  FIGS. 1 and 2 . 
     To further calm and broadly distribute currents in a fluid separator, double-vortex generator  12  can be installed in a pressure vessel  98  that is horizontally elongate, as shown in  FIG. 6 . 
     Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those of ordinary skill in the art. The scope of the invention, therefore, is to be determined by reference to the following claims: