CA2616411A1 - Scale removal apparatus and method - Google Patents

Abstract

A scale removal/prevention apparatus (10, 250) having a generator (15, 260) for generating a signal (120), at least one signal wire (40) electrically connected to the generator (15, 260) which in use is wound around a pipe (70) or other hollow body (70) containing a fluid and circuit means (170) associated with the generator (15, 260) for ensuring that the signal (120) is (i) non continuous (ii) frequency modulated with a varying frequency from approximately 750 Hz to approximately 12.5 KHz and (iii) has a DC offset such that the signal (120) never equals zero.

Description

TITLE
SCALE REMOVAL APPARATUS AND METHOD
FIELD OF THE INVENTION
The invention relates to a method and apparatus for scale removal and/or scale prevention. In particular, the invention relates to a method and apparatus for removing scale from or preventing build up of scale in conduits or other hollow bodies which contain fluid.
BACKGROUND TO THE INVENTION
Water hardness is a measure of the concentration of calcium and magnesium ions in water. High levels of water hardness are common throughout many regions of the world resulting in scale build up within pipes and other water systems. Scale is generally a calcite structure, which forms as a hard white substance. The calcite structure results from the precipitation of calcium carbonate molecules into a regular and dense crystalline structure having a cubic lattice form. Scale commonly affects pipes, valves or plumbing of facilities inclusive of hot water systems, evaporative coolers, heat exchangers and cooling towers. The build up of scale results in energy transfer losses, a higher power usage and an increased cost of operation of hot water systems and boilers. A substantial amount of scale can build up and block the flow of water through pipes or plumbing of such facilities. Scale also promotes the growth of mould, mildew and bacteria.
Systems that involve heating a fluid that is flowing through a conduit are more susceptible to a build up of solid deposits because the heated fluids are more likely to evaporate increasing the likelihood of leaving fat, protein and mineral fouling species. Such species are also sometimes referred to as "scale".
Scale as referred to herein also includes bio-films and bio-active deposits in addition to deposits consisting of fats, proteins, minerals and mineral chelates. It is therefore intended that the term "scale" as used herein includes these alternatives and thus refer to any solid deposits in conduits or other hollow bodies. The invention has particular relevance to removal of scale in food processing or the hygienic-processing-industries-such as dairy foods or milk:
An-example of a process where fluids in conduits are heated is the pasteurisation of milk. The scale that occurs in conduits containing milk and milk products

2 includes a range of species that are deposited when the milk is heated, such as:
fat deposits, protein deposits, beta-lactoglobulin that forms when milk is heated up to 110 C and also minerals and mineral chelates that form deposits when milk is heated above 100 C. Conventional scale removal techniques are not effective at removing the scale that accumulates on the inner walls of conduits containing milk because they are not suited to the distinct properties of milk. Within this specification, references to scale formed inside conduits containing milk include all of the species that form as a deposit when milk is heated through temperature profiles up to and including the processing temperature.
A range of devices have been developed to combat the formation of scale, including: magnetic devices, electro-magnet systems and eiectronic de-scalers.
Magnets and magnetic devices provide a limited scale removal effect and have the disadvantage of attracting impurities such as iron, that coats the area where the magnet is located, further weakening the strength of the magnet.
This process is known as the permanent polarisation effect. Scale removal magnets are very hard to install correctly and furthermore, many experts believe that magnets do not produce any worthwhile results.
Electro-magnetic systems work in a similar manner to magnetic systems, however some of the electro magnetic systems include oscillation of the magnetic field to offset the permanent polarisation effect. The magnetic effect only works for short lineal pipe sections and therefore the system only partially acts on the water that is passing through the section of the pipe and a greater water velocity results in a less effective magnetic system for treating scale.
Electronic de-scalers communicate an electrical signal to coils that are located around or near a pipe. The resulting signals travel over considerable lengths of pipe and hence there is improved protection from scale. Examples of electronic de-scalers are described in United States Patents 5,514,283 and 5,074,998.
United States Patent 5,514,283 discloses an arrangement for treating water to - prevent -and- remove-- scale -deposits. -T-he- arrangement-includes-a primary coil mounted on an exterior of a pipe that is to be treated. An electronic circuit is electrically connected to the primary coil and communicates a

3 succession of radio frequency signals to the coil that create an electromagnetic field in the water. The frequency and amplitude of the energizing signals produced by the circuit is controlled by a microphone input. The microphone rests against the pipe and listens for turbulence. The circuit converts the readings of turbulence to energizing signals and hence the energizing signals that are provided by the circuit are related to the turbulence of the water.
In another embodiment, the energizing signal is then produced according to a transducer installed into the pipe that measures the flow rate of the water.
However, this embodiment is considerably less useful as it can be extremely difficult to install the flow rate monitor into the pipe.
The microphone is not an efficient means of determining the flow rate of the water and hence a large amount of circuitry is required to filter the signal produced by the microphone before it is suitable for energizing the coil. The microphone is also susceptible to interference from other noise sources, which results in an unpredictable signal being supplied to the primary coil. A
further problem is that the apparatus of US Patent 5,514,283 is primarily designed for water and does not provide any means for recalibration so that it is suitable for other fluids having different properties to water.
United States Patent 5,074,998 also describes an apparatus that generates a magnetic field with a coil for preventing the formation of scale in a pipe and also for removing scale from the pipe. An energizing unit provides an energizing signal to the coil that is varied in frequency. This apparatus may also include a flow rate transducer that provides data about the flow rate of the water in the pipe, which can be interpreted by a control unit that is capable of varying the energizing signal accordingly. The flow rate transducer can be either an invasive transducer or an external transducer that is either inductively or thermally coupled to the pipe.
The installation of the invasive transducer creates considerable expense and difficulties as the operation that the pipe belongs to must be shut down and the pipe must be opened for the installation. Hence, the invasive transducers are a-very unattractive--option when retrofitting. -The-inductively- or-thermally coupled transducer overcomes the installation difficulties associated with the invasive transducer. However, the inductively or thermally coupled transducer is a more

4 complicated device and also produces far less accurate results than the invasive transducer. Although an embodiment of the invention is described that does not incorporate a transducer, US 5,074,998 fails to describe a method of calibrating the behaviour of the magnetic field in this instance. Similar to the invention disclosed in US patent 5,514,283, the apparatus disclosed in US 5,074,998 does not accommodate liquids that have different properties to water and hence, will achieve less effective scale removal in these instances.
OBJECT OF THE INVENTION
It is an object of the present invention to overcome or at least alleviate one or more of the aforementioned problems associated with the prior art or to provide a useful commercial alternative.
SUMMARY OF THE INVENTION
In one form, although it need not be the only or indeed the broadest form, the invention resides in a scale removal/prevention apparatus having:
(i) a generator for generating a signal;
(ii) at least one signal wire electrically connected to the generator which in use is wound around a pipe or other hollow body containing a fluid;
(iii) circuit means associated with the generator for ensuring that the signal is (i) non continuous (ii) frequency modulated with a varying frequency from approximately 750 Hz to approximately 12.5 KHz and (iii) has a DC offset such that the signal never equals zero.
The employment of a larger frequency range in the scale removal apparatus of the invention than prior art systems referred to above results in the provision of greater applied frequency-based energy being induced into the fluid-carrying conduit and conduit connected technologies. This provides both the requisite energy and the energy in the requisite form required to initiate a response in larger molecules. Larger deposition molecules form in hygienic process conduits and heating systems than those that form in water based conduits and connected processes. The higher frequency ensures that the rate .of-depos-ition _is-.red-uced- due -to-the continual mobilization -of -larger molecules in-response to the higher range frequency energy. These molecular-mobilizations result in the larger molecules achieving sufficient momentum to overcome the

5 PCT/AU2005/001896 tendency to settle into a crystalline lattice or amorphous deposit, thereby resulting in the material that would otherwise form into a deposit is instead flushed through the process train.
The purpose of the non-continuous signal format is to introduce a dead 5 zone in the frequency sweep or cycling program whereby for a short duration, no signal applies. When incorporated with the large and higher frequency signal output form, the effect of a short duration zero signal band-width is to provide a rapid momentum change to the deposition molecules, already mobilized in response to the induced frequency energy. This rapid, short time frame momentum change induces an additional shock to the deposition molecules effectively providing a dislodgement mechanism to the molecules that further assists in overcoming the tendency for the same molecules to otherwise settle into a crystalline or amorphous deposit.
Preferably, the scale removal apparatus also includes a frequency detector that is electrically connected to a display, wherein the frequency detector is located adjacent to the pipe to detect that the scale removal apparatus has transmitted the signal to the fluid and the display provides verification that the frequency detector has detected that the signal has been transmitted to the fluid.
In another form, the invention resides in a method for preventing scale deposits from forming on an interior surface of a pipe containing a fluid and/or removing scale deposits from the interior surface of the pipe, including the steps of:
(i) winding a number of turns per coil(T) of a signal wire around a pipe containing a fluid, calculated according to the formula, T = (Ka)/(IN) where K is a constant, a is the cross sectional area, I is the current through the signal wire and N is the number of coils;
(ii) electrically connecting a first end of the signal wire to a first terminal of a generator and electrically connecting an opposing end of the signal wire to a-second-terminal of the generator; and -(iii) communicating to the pipe via the signal wire a non continuous signal that is (i) frequency modulated with a varying frequency

6 from approximately 750 Hz to approximately 12.5 KHz, and (ii) which has a DC offset such that the signal never equals zero, wherein K is a constant whose value is derived from the pipe diameter, the total number of signal turns around the pipe, being equal to the number of coils x turns per coil and applied current supplied to the coils and the type of fluid travelling in the pipe.
The units of K are Amp. Total Turns per (metre)2.
Preferably, K is 15,000, + 20%, - 20% when the diameter of the pipe is less than approximately 35mm. For a 20mm diameter piper this equates to around 50 total cable turns around the pipe.
Preferably, K is 15,000, + 20%, -20% when the diameter of the pipe is approximately between 35mm and 100mm. For a 50mm diameter pipe this equates to around 90 total cable turns around the pipe.
Preferably, K is 15,000, +20%, -20% when the diameter of the pipe is 100mm. For a 100mm pipe this equates to around 320 total cable turns around the pipe.
Preferably, K is 15,000, +20%, -20% when the diameter of the pipe is greater than 100mm.
In another form, the invention resides in a scale remover/prevention circuit for providing a signal, including:
a power supply component that provides power for the scale remover/prevention circuit;
a signal generator component that provides a signal;
a signal controller component that is electrically connected to the signal generator component and controls the signal generator component such that the signal provided by the signal generator component is non-continuous and frequency modulated having a frequency that varies in a range from approximately 750 Hz to approximately 12.5 KHz; and an offset component that offsets the non continuous frequency modulated signal-such that--the-signal never equals-zero:

7 Preferably the signal provides rapid cycling with the abovementioned frequency range with each cycle being a single frequency sweep from 750Hz to 12.5 KHz at a rate of up to 25 cycles or sweeps per second.
Preferably, the signal provided by the scale remover circuit has a cycle of about 1/25t" of a second.
Preferably, there is a dead zone having a duration of approximately 6 milliseconds between each cycle.
Preferably, the signal provided by the scale remover circuit is sinusoidal.
Preferably, the signal provided by the scale remover circuit has an amplitude of 4 volts.
Preferably, the signal provided by the scale remover circuit has a DC
offset of 4 volts.
Preferably, the signal generator component incorporates a monolithic function generator.
Further features of the present invention wili become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS
To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein:
FIG 1 shows a schematic diagram of a first embodiment of a scale removal apparatus;
FIG 2 shows a cutaway side view of a coil and a pipe;
FIG 3 shows a graph illustrating the signal qualities of a signal produced by a scale removal circuit against time;
FIG 4 shows a schematic diagram of scale removal circuitry;
FIG 5 shows a schematic diagram of a second embodiment of a scale removal apparatus; and FIG. 6 shows a schematic_diagram of a-third- embodiment of a-scale removal apparatus incorporating a signal detector.

8 DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG 1, there is provided a diagram of a first embodiment of a scale remover/preventer 10 which incorporates a generator 15 having a positive terminal 20 and a negative terminal 30. Electrically connected across the positive terminal 20 and the negative terminal 30 is a signal cable 40. The signal cable 40 forms a first coil 50 and a second coil 60 around a pipe 70. A first turn 80 of the first coil 50 and a first turn 90 of the second coil 60 are attached to the pipe 70 with cable ties, or the like. Similarly, a final turn 100 of the first coil 50 and a final turn 110 of the second coil 60 are attached to the pipe 70 with cable ties, or the like. The first coil 50 and the second coil 60 are separated by a distance the distance equivalent to the pipe length taken by one coil. It should be appreciated that the scale remover/preventer 10 may incorporate only one coil or possibly a greater number of coils. A power supply (not shown) is provided to power the generator 15. When the generator 15 is activated a signal 120, the qualities of which are illustrated in FIG 3, is communicated to the signal cable 40.
The preferred method for calculating the total number of turns of the signal cable 40 around the pipe 70 to create the first coil 50 and the second coil 60 is given by a formula:
turns per coil = (K * cross sectional area of the pipe)/(current * number of coils), which can be abbreviated as:
T = (KQ)/(IN).
The constant K is equal to 15,000, +20%, -20% for all pipe diameters. Hence, an optimum number of turns can be calculated for each individual application of the scale remover/prevention 10, taking into account the different current outputs for different models of the scale remover/preventer itself. It should be appreciated that different values of K can be utilised in different circumstances. For example, when the pipe 70 contains water a different K value might be used than when the pipe 70 contains milk.
When a scale remover/preventer 10 is installed having lesser turns than that value specified by the formula the signal 120 will not provide the requisite frequency-energy values across-the--entire-cross=sectional area-of-the-pipe 70 and hence the scale removing/prevention effect will be lessened. Increasing the number of turns from the number supplied by the formula described above

9 results in only very minor or unnoticeable improvements in the scale removal.
However, the larger number of turns increases the cost of the scale remover 10 and also complicates the installation of the scale remover 10. Furthermore, increasing the number of turns may result in a permanent polarisation effect similar to that experienced by prior art devices that incorporate permanent or oscillating magnets. The formula removes the need to relate the strength of the signal 120 to a speed at which a fluid 140 (shown in FIG 2) is travelling by relating the number of turns of the coils 50 and 60 to the circumference of the pipe 70. In this manner different pipe sizes can be accommodated by the scale remover/prevention 10 without needing the signal 120 to be altered based upon data generated by a transducer.
Referring to FIG 2 there is shown a cutaway view of the pipe 70 and the first coil 50. An electromagnetic field 130, corresponding to the signal 120, is shown surrounding the first coil 50. An electrical signal 150 that corresponds to the signal 120, is induced into the fluid 140 contained in the pipe 70. A net vector effect is produced when the electrical signal 150 adds to a second electrical signal (not shown) that is induced by the second coil 60. The net vector improves the distance that the signal 120 can travel within the pipe 70. The product of Current x Total cable turns influences the amount of frequency-energy generated through the cross-sectional area of the pipe. The first coil 50 and the second coil 60 must both be wound in the same direction to achieve the net vector effect.
Referring to FIG 3, there is provided a graph of voltage against time illustrating the signal qualities of the signal 120, which is communicated at regular intervals from the generator 15 to the signal cable 40. The signal 120 is a frequency modulated sine wave having an initial frequency of about 750 Hz to 3 to 10 KHz for potable and bore water and waters from natural sources and 750 Hz to 12.5 KHz for fluids including dairy, beverages, food stuffs and organic fluids. The frequency range between the 750 Hz and 12.5 KHz is particularly suitable for miik and other beverages having properties that are different to water. Hence the frequency range of 750 Hz to 12500 Hz provides improved -scale removal-or-scale prevention when milk or other-beverages are contained-in the pipe 70. The signal 120 has an amplitude of 4 volts and a 4 volt DC
offset.
The 4 volt DC offset ensures that the signal 120 never reaches 0 volts and hence the signal 120 is constantly producing an effect in the fluid 140 and therefore scale deposits are more effectively removed and prevented. A dead zone 160, having a duration of about 6 milliseconds, is incorporated between the signals 120, and is required to allow the generator 15 time to recalibrate between 5 each signal 120 and also to prevent a permanent polarisation effect, which occurs when a continuous magnetic field is applied and impurities, such as iron, are drawn from the fluid and coat the interior surface of the pipe 70, reducing the effectiveness of the scale remover 10. The signal 120 has a period of about 1/25t" of a second between two consecutive dead zones 160, however, it should

10 be appreciated that other periods would also be suitable.
Referring to FIG 4 there is provided a schematic diagram of a scale remover/prevention circuit 170. The sca(e remover/prevention circuit 170 incorporates a signal generator component 180, an offset component 190, a power supply component 200 and a signal controller component 210.
A 12 volt DC power supply 220 and an 8 volt voltage regulator 230 are incorporated into the power supply component 200. The 12 volt power supply 220 is a PS0520 and the 8 volt voltage regulator 230 is a LM7808CT. It should be appreciated that other varieties of power supply and voltage regulator would also be suitable and that the power levels supplied and regulated could also differ. The 8 volts provided by the 8 volt voltage regulator 230 is converted to 4 volts (VREF) by a voltage divider circuit 235, which incorporates R5 and R6.
The capacitors, resistors and diodes that are incorporated into the power supply component 200 are standard circuitry.
An XR2206 is incorporated into the signal generator component 180, although it should be appreciated that other signal generators would also be suitable. The XR2206 is a mono(ithic function generator, which communicates an output via pin 2 (STO). The output current corresponds to the signal 120 and hence, is frequency modulated from about 750 Hz to 3 to 10 KHz for potable and bore waters and waters from natural sources and about 750 Hz to about 12.5 KHz for fluids including dairy, beverages, food stuffs and organic fluids. A
capacitor G7, which is- electrically- connected- between-pins -1 0-(BfAS) and pin 1-2 (GND), alters the frequency range of the signal 120. A pin 7(TR1) supplies current to the signal controller component 210. The frequency of the signal

11 is directly proportional to the current drawn from pin 7 by the signal controller component 210.
The signal controller component 210 incorporates an op-amp IC1A, which is an LM358 that controls the amount of current that is drawn from pin 7(TR1) and the manner in which the current is drawn. Hence, IC1A sets the time required for the signal 120 to ramp from about .750 Hz to 3 to 10 KHz or from about 750 Hz to about 12.5 KHz.
The offset component 190 incorporates an op-amp IC1 B, which is an LM358, and four current amplifiers Q1, Q2, Q3 and Q4. The two current amplifiers Q1 and Q2, are a BC547 and a BD139, respectively, which are both NPN transistors. The two current amplifiers Q3 and Q4 are a BC557 and a BD140, respectively, which are both PNP transistors. Op-amp IC1 B is electrically connected to the pin 2 (STO) of the XR2206 and also to 4 volt VREF. A diode D3 and a diode D2 are electrically connected to an output of the op-amp IC1 B. A
diode D4 is electrically connected to the diode D3 and to a base of the current amplifier Q3. A diode Dl is electrically connected to the diode D2 and also a base of the current amplifier Q1.
The offset component 190 applies the 4 Volt DC offset to the signal produced by pin 2 (STO) of the XR2206. The offset component 190 is electrically connected to the positive terminal 20 and the negative terminal 30, via CON3 and CON2, respectively.
Referring to FIG 5, there is provided a schematic diagram of a second embodiment of the invention, which incorporates a twin output scale remover/prevention 250. The twin output scale remover 250 incorporates a twin output signal generator 260 having positive terminals 260 and 265 and negative terminals 270 and 275. A second signal cable 280 and the signal cable 40 are electrically connected between positive terminal 260 and negative terminal 270 and positive terminal 265 and negative terminal 275, respectively. The signal cable 40 is wound around the pipe 70 to form the first coil 50 and the second coil 60. The second signal cable 280 is wound around the pipe 70 to form two coils - -2-90- and- 300. -I-t is important that the- coils -50160; 290--and- 300 are all wound around the pipe 70 in the same direction.

12 The twin output scale remover 250 is installed in the same manner as the scale remover/preventer 10. The signal 120 is communicated from the twin output signal generator 260 to the signal cable 40 and the second signal cable 280.
Referring to FIG 6, there is provided a schematic diagram of a third embodiment of the invention incorporating a signal detector 310. The signal detector 310 incorporates a frequency receiver 320 that is electrically connected to a signal detector module 330 by a detector wire 340. A strap 350 secures the frequency receiver 320 to the pipe 70 such that the frequency receiver 320 is in constant contact with the pipe 70. The signal detector module 330 includes a power supply (not shown) for powering the signal detector 310 and a power indicator light 360 to indicate that the signal detector 310 is powered. A
detector circuit (not shown), included in the signal detector module 330, converts the signal received by the frequency receiver 320 to a signal that is displayed by a display light 370.
The signal detector 310 allows an operator to determine that the scale remover is functioning correctly. Without the signal detector 310 there is no indication that the signal 120 is being transmitted to the fluid 140, and hence an operator will not be aware that the scale remover/prevention 10 is not functioning correctly until a large volume of scale has built up in the pipe 70 and has adversely affected the flow of the fluid 140 through the pipe 70. In use, the frequency receiver 320 is attached to the pipe 70 by the strap 350 and the power supply provides power for the detector circuit. When the frequency receiver receives the signal 120, the signal 120 is communicated by the detector wire to the detector circuit, which then communicates the signal 120 to the display light 370. When the signal 120 is communicated to the display light 370, the display light 370 flashes providing a visual signal that verifies that the signal 120 has been transmitted to the fluid 140.
Hence, the method and apparatus of the present invention provides a solution to the problem of scale accumulation in pipes and within hygienic pr-ocess-technologies containing--fluids - by--virtue- of --coils carrying- a--specific frequency modulated signal that are wound around the pipes.
The scale remover/preventer is suitable for preventing scale accumulation

13 in conduits containing water and in conduits containing fluids with properties different to the properties of water, such as milk. The scale remover/prevention is also easy to install and further, does not require the installation of a transducer.
The invention described herein applies to the treatment and prevention of deposit formation in processing equipment and in connecting conduits, of products of the hygienic processing Industries, that includes all of but is not limited to, the following:
(i) Dairy Products including full milk, skim milk, butter milk, cream, whey products, fat reduced milks, cheese pre-cursors and any milk products with additives included or components removed. The application also includes lactose production, evaporation and processing systems. Also included are yoghurt based products, soy milk products and flavoured milk products;
(ii) Other food products including fruit juices, soft drinks, vegetable juices, coffee, tea and soy based drinks, protein health drinks, yeast extracts and other food additives in liquid form including pharmaceutical and herbal preparations;
(iii) The processing of sugar juice in the production of sugar from sugar cane, sugar beet and other sugar bearing materials;
(iv) Petrochemical species, both crude and refined and synthesized organic based products;
(v) Brewery processing and beer, stout and other alcoholic based yeast and/or sugars processing applications for the production of alcoholic drinks. Additionally, the applications include the conveyancing lines for the same, both within breweries and within the dispensing lines where the product is purchased and/or consumed; and (vi) Minerals processing and metals refining and inorganic industries including fertilizers, pigments and coatings.
The range of applications includes the processing of the above at temperatures below 100C and up to ultra heat treatment temperatures in the range-between-1 OOC to-in-excess-of 140C.
The invention applies to the treatment and/or prevention of deposit formation within, but is not limited to, the following processing technologies:

14 Plate Heat Exchanger Technologies Tubular Heat Exchanger Technologies Lactose Evaporator Technologies Sugar Juice Evaporator Technologies Sterilization Technologies Ultra Heat Treatment Technologies Distillation and Vapour Formation Technologies Fermentation Systems Bio-active kettles and Vats Reaction Vessels Catalysis Processing Technologies Petrochemical Processing Technologies Wet Scrubbers, Coagulators, Precipitators and Centrifuges The technologies stated above also include the conduits used to convey fluids to and from each.
Attached herewith is a Table X showing determination of the constant K
on various values of the relevant parameters as described above.

TABLE

Determination of Constant K

Turns Pipe Diam Current Total per K - Factor mm mAmp Turns # Coils Coil x 10,000 Model 100 50 2 25 1.56 LC-1 100 76 2 38 1.52 LC-1 38 350 50 2 25 1.54 LC-2 50 350 90 2 45 1.54 LC-2 63 350 144 4 36 1.54 LC-2 68 350 162 4 40 1.54 LC-2 75 350 200 4 50 1.47 LC-2 100 350 320 4 80 1.40 LC-2 Pipe length Voltage = 12 Volt DC Input max @100mm 12 V DC 500 mA
320x2mm V ref at 4 Volt DC
plus 3 x 80 x LC-2 Input 2mm V Amplitude 4 Volt DC 12 V DC 1 Amp 1.12m of pipe Turns x K Coils x Currentl pipe unit area 5 For pipes greater than 100 mm diameter, a Model LC-3 is used with requisite Current output and Total Turns to provide a K-Factor of 15,000 +/- 20%

Claims (21)

CLAIMS:

1. A scale removal/prevention apparatus having:
(i) a generator for generating a signal;
(ii) at least one signal wire electrically connected to the generator which in use is wound around a pipe or other hollow body containing a fluid;
(iii) circuit means associated with the generator for ensuring that the signal is (i) non continuous (ii) frequency modulated with a varying frequency from approximately 750 Hz to approximately 12.5 KHz and (iii) has a DC offset such that the signal never equals zero.

2. A scale removal/prevention apparatus as claimed in claim I
wherein the circuit means provides rapid cycling of the frequency range with each cycle being a single frequency sweep from 750Hz to 12.5 KHz at a rate up to 25 cycles or sweeps per second.

3. A scale removal/prevention apparatus as claimed in claim I or 2 further including a frequency detector electrically connected to a display wherein in use the frequency detector is located adjacent the pipe or other hollow body to detect that the signal has been transmitted to the fluid whereby the display provides verification of this.

4. A scale removal/prevention apparatus as claimed in claim 1, 2 or 3 wherein the signal wire forms a first coil and second coil when wrapped around a pipe or hollow body which are spaced from each other.

5. A scale removal/prevention apparatus as claimed in claim 4 wherein the first coil and the second coil are separated by a distance equivalent to the pipe length taken by either coil.

6. A scale removal/prevention apparatus as claimed in claim 4 or 5 wherein the successive turns of each of the first and second coils are all in the same direction.

7. A scale removal/prevention apparatus as claimed in claim 1, 2 or 3 wherein a first signal wire forms a first and second coil and a second signal wire forms a third and a fourth coil wherein each of the first, second, third and fourth coils are wound around a pipe or hollow body and are spaced from each other.

8. A scale removal/prevention apparatus as claimed in claim 7 wherein each of the first, second, third and fourth coils are spaced from each other by a distance equivalent to a pipe length taken by any of the coils.

9. A scale removal/prevention apparatus as claimed in claim 7 or 8 wherein each of the first, second, third and fourth coils are all wound in the same direction.

10. A method for preventing scale deposits from forming on an interior surface of a pipe as well as removal of the scale deposits from said interior surface, said method including the steps of:
(i) winding a number of turns per coil(T) of a signal wire around a pipe containing a fluid, calculated according to the formula, T = (K.sigma.)/(IN) where K is a constant whose value is derived from the pipe diameter, the total number of signal turns around the pipe, being equal to the number of coils X
turns per coil and applied current to the coils and the type of fluid travelling in the pipe, a is the cross sectional area, I is the current through the signal wire and N
is the number of coils;
(ii) electrically connecting a first end of the signal wire to a first terminal of a generator and electrically connecting an opposing end of the signal wire to a second terminal of the generator; and (iii) communicating to the pipe via the signal wire a non continuous signal that is (i) frequency modulated with a varying frequency from approximately 750 Hz to approximately 12.5 KHz, and (ii) which has a DC offset such that the signal never equals zero.

11. A method as claimed in claim 10 wherein K is 15,000 ~ 20% when the diameter of the pipe is less than 35mm.

12. A method as claimed in claim 10 wherein K is 15,000 ~ 20% when the pipe has a diameter of between 35100mm.

13. A method as claimed in claim 10 wherein K is 15,000 ~ 20% when the diameter of the pipe is 100mm or greater.

14. A scale remover or scale prevention circuit which includes a power supply component that provides power for the scale remover/prevention circuit;

a signal generator component that provides a signal, a signal controller component that is electrically connected to the signal generator component and controls the signal generator component such that the signal provided by the signal generator component is non-continuous and frequency modulated having a frequency that varies in a range from approximately 750 Hz to approximately 12.5 KHz; and an offset component that offsets the non continuous frequency modulated signal such that the signal never equals zero.

15. A circuit as claimed in claim 14 wherein the signal provides rapid cycling of the frequency range with each cycle being a single frequency sweep from 750Hz to 12.5 KHz at a rate up to 25 cycles or sweeps per second.

16. A circuit as claimed in claim 14 wherein the signal has a cycle of about 1/25th of a second.

17. A circuit as claimed in claim 14, 15 or 16 wherein there is a dead zone of approximately 6 milliseconds between each cycle.

18. A circuit as claimed in any one of claims 14 to 17 wherein the signal is sinusoidal.

19. A circuit as claimed in any one of claims 14 to 18 wherein the signal has an amplitude of 4 Volt.

20. A circuit as claimed in any one of claims 14 to 19 wherein'the signal has a DC offset of 4 Volt.

21. A circuit as claimed in any one of claims 14 to 20 wherein the signal generator component incorporates a monolithic function generator.