US 3835015 A
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United States Patent O 3,835,015 SYSTEM STABILIZER Wildon A. Gary, 305 NW. 7th Ave., Mineral Wells, Tex. 76067 Filed Nov. 15, 1972, Ser. No. 305,091
Int. Cl. C23f 13/00 US. Cl. 204-197 26 Claims ABSTRACT OF THE DISCLOSURE A fluid stabilizer rod consists of an alloy of copper, zinc, nickel and tin adapted to be installed in a fluid conduit and to have a fluid flowing thereover. The rod is generally elongated and triangular in cross-section with each side thereof defining a lengthwise extending concave arcuate surface.
BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to apparatus for controlling scale deposition and, more particularly, to a fluid stabilizing rod having a metallurgical composition and physical configuration specifically adapted to inhibiting scale deposition.
Description of the Prior Art A well known problem associated with oil and water wells is the accumulation of parafiin and scale in, as well as the corrosion of, the flow tubes, pumps and other equipment associated with the well. The problem is par ticularly acute where the mineral content of the fluids flowing in the well system is high and the deposition of compounds of these minerals is correspondingly high, causing operational, production and economic difliculties. Particularly bothersome are compounds, such as calcium carbonate and/or sulfate, iron oxide and/or sulfide, as well as hydrogen sulfide, free sulfur and sodium salts.
One solution to this problem heretofore suggested is to preclude, to the greatest extent possible, deposition of precipitates of these mineral compounds. If the com pounds could be maintained in colloidal or suspension form, then they could not scale or erode tubing walls and equipment surfaces and the problems associated with their presence would be largely ameliorated. US. Pat. No. 3,448,034 to Craft teaches that a stabilizing element comprising a metal core housed in a flow tube has a polarizing efiect on the fluid in the tube to eliminate any affinity between the mineral compounds and the surfaces of the flow system, thereby preventing precipitation of the compounds. Crafts core is generally oval in crosssection and has a composition consisting of 57.64% cop per, 17.63% zinc, 13.45% nickel, 7.66% lead, 2.69% tin, and .69% iron and trace amounts of antimony, sulfur and manganese. US. Pat. No. 3,486,999 to Craft, et al., teaches a particular apparatus configuration to accomplish the polarization of the fluid using a primarily copper, zinc, silicon core.
The prior art devices function only to a somewhat limited extent; it having been found that they are largely inefficient in preventing scale formation and corrosion. This inefiiciency is in part attributable to the metallurgical composition of the rod, but to a greater extent is attributable to a failure to provide an optimum core configuration in terms of the two key variables of pressure drop (and thus fluid velocity) and surface area.
SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fluid stabilizing rod which controls and inhibits scale deposition by virtue of its metallurgical composition and physical configuration.
3,835,015 Patented Sept. 10, 1974 ice It is another object of the invention to provide a fluid stabilizing apparatus which provides a controlled pressure drop thereacross and therefore contributes to controlling fluid velocity as well as fluid chemistry.
It is still another object of this invention to provide apparatus which controls scale deposition by utilizing flow velocity to determine the size and quantity of precipitates formed in the fluid.
Other objects and advantages will become apparent from the following description and appended claims.
Briefly stated, in accordance with the aforesaid objects, the present invention provides an elongated fluid stabilizing rod consisting of an alloy of copper, zinc, nickel and tin adapted to be installed in a fluid conduit and to have a fluid flowing thereover. The rod is generally triangular in cross-section with each side thereof defining a length wise extending, concave arcuate surface. Fluids flow over and in contact with the arcuate surface. The apices of the triangle contact a cylindrical casing in which the rod is enclosed to permit a force or press fit of the rod therein. Alternatively, the rod may be retained in the casing by washers disposed at each end of the rod and secured to the casing. In one embodiment of the present invention, the rod has a lengthwise extending passageway formed therethrough to increase the surface area of the rod available for fluid contact.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood from the following description taken in conjunction with the accompanying drawings.
FIG. 1 is a perspective view of the fluid stabilizing rod of the present invention.
FIG. 2 is a perspective view of the apparatus of the present invention with portions broken away showing the rod press fit into a cylindrical casing therefor.
FIG. 3 is a sectional view taken substantially along the line 33 of FIG. 2.
FIG. 4 is a perspective view of the apparatus of the present invention with portions broken away showing the rod held in a cylindrical casing by washers secured to the casing.
FIG. 5 is a sectional view taken substantially along the line 5-5 in FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION The fluid stabilizer rod of the present invention is primarily a device to control scale deposition. It does not prevent scale from forming, but provides an effective method of controlling where it forms. More particularly, the rod permits scale compound precipitates to form in the flowing fluid but, by virtue of its composition and configuration, controls the size of the precipitates and thus their tendency or ability to settle on the flow tube and equipment surfaces.
Referring to FIG. 1, there is shown generally at 10 the fluid stabilizer rod of the present invention. Rod 10 is generally elongated and is tapered or nosed at each end 12, 14 to provide smooth fluid pressure transitions at the ends. In cross-section, rod 10 is generally triangular except that sides or surfaces 16, 18, 20 are inwardly bowed or hollowed to define lengthwise extending, concave arcuate surfaces. The generally triangular cross-section includes lengthwise extending apices 22, 24, 26 at the intersections of sides 16 and 18, 18 and 20, and 20 and 16, respectively. Apex 24 has lugs 28 thereon to accommodate variations in the inner diameter of casings in which rod 10 is inserted. Lugs 28 extend outwardly from apex 24 along the bisector of the excluded angle of the apex, i.e., the excluded angle formed by the intersection of sides 18 and 20. Surfaces 16, 18, 20 each include projections 30 thereon extending outwardly from the surfaces and disposed perpendicularly to the longitudinal axis of the rod. As fluid flow proceeds along the longitudinal axis of the rod, over and in contact with surfaces 16, 1S and 20, projections 30 (two are shown on each surface; however, three or more are preferred on long rods) tend to break up the boundary layer and thereby increase fluid turbulence. Increased turbulence and the attendant increased mixing effect enhances the extent of surface contact between surfaces 16, 18, 20 and the fluid, thereby increasing the effective fluid contact areas of these surfaces.
Rod is preferably installed in a cylindrical casing or flow tube 32, as shown in FIG. 2, and retained therein by a friction or press fit between lugs 28 and the inner wall 34 of the tube 32. As a practical matter, upon force fitting rod 10 in tube 32, lugs 28 tend to deform with the result that apices 22, 24, 26 are in substantial contact with wall 34. As shown in FIG. 4, an alternative means of retaining rod 10 in casing 32 is to provide circumferential washers 36 welded or otherwise secured to the inner wall 34 of the casing near the ends 12, 14 of the rod 10. When washers 36 are used as the retaining means, rod 10 preferably has a shoulder 38 formed in each apex adjacent nosed ends 12, 14 such that the ends 12, 14 project through washers 36 with shoulders 38 engaging the inwardly facing surfaces 40 of the washers.
In an alternative embodiment, rod 10 may include a longitudinally extending passageway 42 through the center of the rod to provide an additional fluid flow channel. Preferably, passageway 42 has the same cross-sectional configuration as the rod, i.e., generally triangular with the sides thereof defining longitudinally extending, convex arcuate surfaces 44, 46, 48. These latter surfaces are substantially parallel to corresponding surfaces 16, 18, 20, respectively, and provide substantially increased surface area for contact with the flowing fluid.
In use, rod 10 is inserted and retained within casing 32 and, in this configuration, is installed in a flow system, such as an oil or water well, a steam boiler, or the like, without need to modify the system. Generally, the diameter of casing 32 corresponds to the diameter of the tubing in the system unless some smaller diameter casing is necessary to assure a minimum flow rate over surfaces 16, 18, 20. When rod 10 is furnished already inserted within a flow tube, such as casing 32, the casing may include means, such as external threads 50, for installing the tube in the system. Alternatively, the tube may be welded or otherwise fluid-tightly inserted and secured into the system. The fluid is caused to flow into one end of the casing 32, whereupon it divides over nosed end 12 to flow through the three passageways 52, 54, 56 bounded by each of arcuate surfaces 16, 18 and 20 and inner wall 34. Turbulent flow occurs in each passageway causing mixing therein and extensive contact between the fluid and surfaces 16, 18, 20 whereby polarization of the min erals in the fluid occurs. Enhanced polarization is achieved in accordance with the present invention by virtue of the arcuate nature of the surfaces and the particular configuration of rod 10 to provide maximum surface area for fluid contact. The fluid leaves each of the defined passageways, re-mixes as it flows over nosed end 14 and leaves casing 32. t 1
Without wishing to be bound to any particular theor of operation, it is believed that the polarizing effect is due to strong electrochemical reactions involving the metals of the rod in a scale forming environment. Due to the composition of the rod, numerous positive and negative poles are developed on its surface when installed in a conductive environment. Charged mineral ions in the fluid are drawn to the poles on the rod and the result is a substantial concentration of a portion of the ions in solution. As the scale forming ions are attracted to the metal surface, their concentration increases and scale compounds begin to precipitate. The quantity and size of the precipitates is influenced, however, by the core configuration. By virtue of the cross-sectional configuration of the core, a minimum pressure drop across its length is developed. This pressure drop aids in releasing dissolved acid forming gases, such as carbon dioxide and hydrogen sulfide, causing a slight in situ alteration of the fluid chemistry. This alteration increases scaling tendencies and influences the quantity of precipitates formed. Likewise, due to the pressure drop and the water velocity through the passageways, only sub-microscopic precipitates have time to form before they are swept downstream. The small 1 size of the precipitates provides a desired colloidal dispersion that functions as a surface for further mineral ion precipitation. Thus, the great surface area of these sub-' microscopic precipitates creates a colloid eifect whereby additional ions precipitate thereon, with the net effect that scale forming precipitates are kept in the fluid and in motion and are unable to settle onto system surfaces. It is believed that this mechanism explains the phenomena often observed by which scale formation is not only prevented but existing scale deposits are diminished or removed. This occurs because scale formation is a dynamic process involving continuous deposition, erosion and re deposition. Inasmuch as the fluid stabilizing rod of the present invention effectively precludes deposition and redeposition, erosion becomes the controlling factor and existing scale deposits decrease.
As exemplary embodiments of the fluid stabilizing apparatus, rod 10 has been manufactured in lengths from about 10 to 42 inches and in over-all widths suitable for insertion into cylindrical casings having internal diameters ranging from to 14 inches. Generally, length and width (diameter) are correlated with the length increasing with increasing width (diameter). It will be appreciated that as the width (diameter) increases, the rods become quite massive and, notwithstanding their concave outer surfaces, become a substantial impediment or restriction to flow through the cylindrical casing. Accordingly, in the alternative embodiment, a lengthwise extending passageway is formed in the rod to provide additional flow area and, at the same time, additional surface area. It has been found that maximum rod effectiveness is achieved in an apparatus wherein the rod presents an area restriction to flow through the casing of about 38 to i.e., the percent ratio of flow area through a casing including a rod therein to flow area through an empty casing is in the range 38 to 40%. The pressure drop thus created together with a minimum flow velocity of about 3 feet per second over the extensive surface area of the rod of the present invention insures maximum effectiveness in polarizing the fiuid.
The fluid stabilizing rod is formed of an alloy of copper, zinc, nickel and tin by melting the alloy at about 1900-2100 F. and then sand casting the rods to the desired shape. Effective rod compositions are in the range, by weight, of 40-50% copper, 20-30% zinc, 15-25% nickel and 9-15 tin. A particularly preferred composition is copper, 25% zinc, 20% nickel and 10% tin. Rods having compositions in the aforementioned ranges have been found to be substantially non-sacrificial or only slowly sacrificial with useful lives in normal use up to about ten years.
While the present invention has been described with reference to particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually departing from the scope thereof. Accordingly, all modifications and equivalents may be resorted to which fall within the scope of the invention as claimed.
What is claimed as new is as follows:
1. A fluid stabilizing metal rod adapted for insertion into a conduit having fluid flowing therein comprising an elongated rod having a generally triangular cross-section, each side thereof defining a lengthwise extending, concave arcuate surface.
2. A rod, as claimed in claim 1, further including a plurality of lugs extending outwardly from at least oneof the apices of the triangle along the bisector of the excluded angle of said apex.
3. A rod, as claimed in claim 2, wherein said plurality of lugs comprises two lugs equally spaced from opposite ends of said rod.
4. A rod, as claimed in claim 1, further including a plurality of projections extending outwardly from each said surface.
5. A rod, as claimed in claim 4', wherein said projections on each said surface are disposed transverse to the longitudinal extent thereof.
6. A rod, as claimed in claim 1, wherein said rod is hollow and includes a lengthwise extending passageway therethrough defining a fluid flow channel therein.
7. A rod, as claimed in claim 6, wherein said passageway is generally triangular in cross-section, each side thereof defining a lengthwise extending, convex arcuate surface.
8. A rod, as claimed in claim 1, wherein said rod comprises an alloy of copper, zinc, nickel and tin.
9. A rod, as claimed in claim 8, wherein said rod comprises, by weight, 40-50% copper, 20-30% zinc, 1525% nickel and 9-15 tin.
10. A rod, as claimed in claim 9, wherein said core comprises, by weight, 45% copper, 25% zinc, 20% nickel, and 10% tin.
11. A rod, as claimed in claim 1, further including a plurality of lugs extending outwardly from at least one of the apices of the triangle along the bisector of the excluded angle of said apex and a plurality of projections extending outwardly from each said surface, said rod comprising an alloy having a composition in the range, by weight, 4050% copper, 2030% zinc, -25% nickel and 9-15 tin.
12. A rod, as claimed in claim 11, wherein said projections on each said surface are disposed transverse to the longitudinal extent thereof.
13. Apparatus for stabilizing fluids comprising an elongated fluid stabilizing metal rod having a generally triangular cross-section, each side thereof defining a lengthwise extending, concave arcuate surface and a cylindrical casing circumferentially surrounding said rod, at least one of the apices of the triangle engaging the inner walls of said casing and said arcuate surfaces defining with said inner walls passageways for the flow of fluids through said casing.
14. Apparatus, as claimed in claim 13, wherein at least one of said apices includes a plurality of lugs extending outwardly therefrom along the bisector of the excluded angle of said apex for engaging said inner walls.
15. Apparatus, as claimed in claim 13, wherein each of said surfaces includes a plurality of projections extending outwardly therefrom, said projections disposed perpendicularly to the direction of fluid flow along each said surface.
16. Apparatus, as claimed in claim 13, wherein said rod is hollow and includes a lengthwise extending passageway therethrough defining a fluid flow channel therein.
17. Apparatus, as claimed in claim 16, wherein said passageway is generally triangular in cross-section, each side thereof defining a lengthwise extending, convex arcuate surface.
18. Apparatus, as claimed in claim 16, including washer means secured within said casing at each end of said rod for retaining said rod in said casing.
19. Apparatus, as claimed in claim 18, wherein said rod has nosed ends and a shoulder on each said apex adjacent said ends and said rod is disposed in said casing with said ends projecting through and said shoulders seated on said washer means.
20. Apparatus, as claimed in claim 13, wherein said rod comprises a 38 to 40% flow area restriction in said casing.
21. Apparatus, as claimed in claim 13, wherein said rod comprises an alloy of copper, zinc, nickel and tin.
22. Apparatus, as claimed in claim 21, wherein said rod comprises, by weight, 4050% copper, 20-30% zinc, 15- 25% nickel and 915% tin.
23. Apparatus, as claimed in claim 22, wherein said rod comprises, by weight, 45% copper, 25% zinc, 20% nickel and 10% tin.
24. Apparatus, as claimed in claim 20, wherein said rod comprises an alloy having a composition, by weight, of 4050% copper, 20-30% zinc, 15-25% nickel and 9- 15 tin.
25. Apparatus, as claimed in claim 13, wherein each of said surfaces includes a plurality of projections extending outwardly therefrom.
26. Apparatus, as claimed in claim 25, wherein said projections on each said surface are disposed transverse to the longitudinal extent thereof.
References Cited UNITED STATES PATENTS 3,486,999 12/1969 Craft 204197 3,448,034 6/1969 Craft et al. 204248 3,313,721 4/1967 Teel 204280 3,125,499 3/1964 Bender 204197 3,470,077 9/ 1969 Higgins 204289 2,392,033 1/1946 Eaton 204197 1,43 5,671 11/ 1922 Stewart 204280 TA-HSUNG TUNG, Primary Examiner US. Cl. X.R. 204148