Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
1999-04-09
2001-09-18
Donovan, Lincoln (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C210S222000
Reexamination Certificate
active
06292085
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an apparatus that reduces the formation of “scale” inside pipes or vessels which carry water or other fluids and, more particularly, the invention relates to the induction coils that are wrapped around such pipes as part of the apparatus.
BACKGROUND OF THE INVENTION
The formation of scale inside of pipes that transport water and other fluids is both a common and serious problem. This holds true for industrial as well as residential applications. The reason is that most fresh water in the United States can be regarded as “hard.” Hard water contains mineral ions, such as calcium and magnesium, which are dissolved in the water but precipitate out over time onto the interior surfaces of pipes and other conduits through which the water travels.
More particularly, in scale formation, supersaturated mineral ions (such as calcium) in the water combine with counter-ions (such as bicarbonate) and then precipitate out of solution and deposit on scale-susceptible surfaces.
As scale deposits on the inside surface of the pipe accumulate, the effective diameter of the pipe is reduced, thereby restricting the flow of water. (In a vessel for holding water, scale reduces the vessel's capacity.) This is an especially acute problem when the water is used in a heat transfer situation such as a boiler. Since the scale deposits act as a heat insulator, it contributes to the further deleterious effect of reducing the efficiency of the heat transfer. This reduction can be very expensive, causing as much as 70% of the overall cost of the heating fuel to be wasted.
One way of dealing with scale deposits is to physically remove the deposits by such procedures as sand blasting, acid cleaning, mechanical scraping or brush punching. However, these procedures generally require at least some disassembly of the equipment in which the scale deposits have formed, with consequent interruption in the operation of that equipment, in addition to the cost of the procedures themselves. Moreover, these physical methods of removing the scale may damage the pipe or other pieces of equipment. Furthermore, certain sections of pipe may be inaccessible to a scraper or brush, making it impossible to remove the scale with a physical procedure.
Procedures using physically non-invasive steps are known in the art. For example, it is known to wrap a wire in an elongated, spiral configuration around a segment of the pipe, upstream from the location where the scale deposits would normally form. The spirally-wrapped wire forms an induction coil. A time-varying electric current is passed through the coil, thereby creating a time-varying magnetic field inside the segment of pipe around which the wire is wrapped. That magnetic field produces induction and this induction in turn causes the mineral ions to precipitate out of the water. This effect by an electronic descaling apparatus is called “controlled precipitation”.
Calcium carbonate precipitates are capable of assuming two predominant crystal structures. One of these crystal structures floats in solution and can be carried away by the water flow; the other crystal structure tends to cling to the lateral pipe surfaces and/or to sink to the bottom and hence accumulates to form the undesired deposits.
It is a goal in controlled precipitation to promote the first crystal structure which floats in the water. This is achieved by forming, upstream of the region of the potential scale deposits, seed crystals of the above-described structure which float in solution. These seed crystals cause subsequent mineral carbonate precipitates of the same structure to grow around them. These precipitates then pass through the (downstream) region of potential scale deposits without causing the (undesired) formation of such deposits.
As previously noted, a known technique for effecting controlled precipitation involves spirally wrapping an induction coil around the above-mentioned upstream portion of the pipe and energizing this coil with a time-varying electric current. This current in the induction coil creates a time-varying magnetic field inside the pipe and that field, in turn, causes induction which then in turn produces the desired controlled precipitation.
This known technique is relatively effective in dealing with undesired scale formation, but there are situations in which its implementation is problematic. For example, there are installations in which the diameter of the piping around which the induction coil would need to be wound is so large (as much as 84 inches in some electric power generating plants) that it would be impractical to wrap the required induction coil around the perimeter of the pipe due to its physical size and the large impedance created by the long length of wire needed to form a large diameter coil.
As another example, there are installations in which the piping is in such tight quarters, or so close to other equipment, that it would again be impractical to wrap the induction coil around the outer perimeter. Also, the larger the diameter of the pipe, the greater the electric current that is needed to effect the precipitation of the calcium carbonate.
SUMMARY OF THE INVENTION
The present invention comprises a plurality of individual induction coils that are connected together in an electrical parallel connection. Each coil is comprised of a length of flat wire attached to a correspondingly flat support surface, such as a flexible sheet of plastic or nonferrous metal. To protect the flat wire from damage, it is preferably overlaid with another such flexible sheet.
The flat wire is formed in a substantially planar, spiral-like configuration. The turns of the spiral-like configuration are preferably not round, but are elongated in the same general direction, so as to form a coil of a generally rectangular shape, with a wire-free central portion extending lengthwise of the rectangle.
Thus, there is created a rectangular sandwich-like assembly of spiral-like, flat wire, flanked by cover sheets. This assembly is relatively thin (preferably only fractions of an inch in thickness). It is also flexible, since both the wires and their cover sheets are chosen so as to be inherently flexible.
Each individual coil is arranged so that the short side of one rectangularly-shaped coil overlays the short side of its immediately adjacent rectangularly-shaped coil. This forms a flat, elongated rectangular coil assembly which is rolled around the perimeter of the pipe segment in which the desired controlled precipitation is to be achieved. The longitudinal direction of each wrapped rectangular coil is substantially concentric with the wall of the pipe. An axis through the center of each rectangularly-shaped coil would intersect and be substantially perpendicular to the longitudinal axis of the pipe.
In so doing, the coil assembly is positioned so that its lengthwise dimension extends circumferentially with respect to the pipe.
When the coil assembly is energized by a time-varying electric current, an oscillating electric field is created through which the water flows. The oscillating electric field causes the desired controlled precipitation of calcium carbonate out of the water that flows through the pipe section around which the coil assembly is wrapped. The oscillating electric field also tends to promote the formation of the calcium crystal structure that floats in water rather than the crystal structure that accumulates.
Although the preferred embodiment utilizes three coils, additional flat, rectangularly-shaped coils in accordance with this invention can be added to work as intended with large-diameter pipes. By virtue of its thinness and inherent flexibility, it can readily be applied to pipes in restricted locations. When so applied, it can be held in place either by adhesive on the exposed surface of one of the plastic sheets, or by ordinary cable ties or other clamps surrounding the sandwich-like structure and any portions of the pipe circumference not covered by the sandwich-like structure.
REFERENCES:
pate
Donovan Lincoln
Electronic Descaling 2000, Inc.
Lipton, Esq. Robert S.
Lipton, Weinberger & Husick
Nguyen Tuyen T.
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