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News Release from: Environmental Treatment Concepts | Subject: Scalewatcher
Edited by the Processingtalk Editorial
Team on 11 February 2003
Eliminating hard water scale
The Patented Scalewatcher-Enigma EWT is a non-invasive system utilising a solenoid coil or coils wrapped around the pipework to prevent the precipitation and deposit of Hard water scale
The problems of scale are well known to those living and working in 'Hard' water areas Scale is the undesirable consequence of water supplies becoming supersaturated with dissolved minerals
This article was originally published on Processingtalk on 11 Nov 2004 at 8.00am (UK)
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These problems are of greater significance if found in industrial water systems and commercial buildings.
Scaling problems commonly occur, even in 'Soft' water areas, when a fluid stream is recirculated: liquid losses cause concentration of the dissolved mineral ions, and eventually force the minerals to precipitate at their solubility limit.
In process industries, it is common for chemicals to be added either because the water is being used for 'scrubbing' or cleaning, or to achieve a chemical/mineral effect as part of the production process, so increasing the scaling tendency.
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Scaling deposits are very common in flowlines subject to changes in pressure or temperature.
Regardless of how hard water effects are achieved, the outcome is the same for all.
Scale fouling results in reduced diameter or blocked pipes, reduced heat transfer efficiency, seized pumps, inoperable valves, misleading meter readings, defective heating elements, etc Aqueous solutions can become supersaturated, which means they contain higher concentrations of dissolved solute than their equilibrium concentration.
Such solutions are not stable and are easily triggered into dropping back to saturation level, forcing the dissolved compound to precipitate.
Even when a bulk solution is less than fully saturated, scale formation can occur spontaneously due to localised supersaturation, at a surface for example.
The pH of the solution is directly related to its acid content (typically carbonic acid).
The higher the acid content, the lower the pH number.
The solubility of calcium carbonate is directly affected by the pH of the water.
If the pH of the water is decreased, more calcium carbonate solid can be dissolved.
Conversely, if the pH of the water rises, it will force calcium carbonate out of solution and hence scale deposits will form.
Gases in general, and specifically carbon dioxide, are less soluble in water at high temperatures.
Therefore, as the temperature rises, the dissolved carbon dioxide decreases.
This increases the pH of the fluid, reducing the solubility of the calcium carbonate and forcing the mineral to deposit.
Carbon dioxide and gases in general are more soluble under higher pressure.
Therefore, as the pressure drops, carbon dioxide gas will be forced out of solution, lowering the carbonic acid concentration.
The rise in pH is associated with a drop in calcium carbonate solubility, leading to the formation of mineral scale deposits.
The Patented Scalewatcher-Enigma EWT is a non-invasive system utilising a solenoid coil or coils wrapped around the pipework to be treated.
A signal generator supplies current to the coils, and the frequency is continuously changed, typically within the range 100-5000Hz.
The pulse shaped current creates an induced electric field, concentric around the axis of the pipe.
As a consequence to this arrangement, any particle that moves within the field experiences an induced electric field and a "Lorenz" type force of approximately equal magnitude, irrespective of flow rate.
Tests at Drexel University in America confirm the induced (electric) field is unchanged, irrespective of flow rate.
Residual magnetic fields have been measured and have been found to be below 1 gauss.
This technology overcomes one major disadvantage of permanent magnet devices, viz, that they work well only within a certain flow rate "window" and that at higher and lower flows the performance drops to zero.
The Scalewatcher-Enigma EWT affects the formation of scale by increasing the homogeneous precipitation rate of calcium carbonate and certain other minerals.
The ability to adjust power, frequency and coil configurations on site enables performance to be optimised with no downtime and no pipe replacement.
Current scientific literature describes the macro effects of electronic scale treatment, which are the consequence of fundamental interactions between applied fields and precipitating substances.
The amount of energy that is introduced by a solenoid coil is very small (the consumption of a Scalewatcher-Enigma unit is one order of magnitude less than a cordless telephone).
To study the induced fields, scientific tools of high precision are needed which do not interfere with the interactions that we want to measure.
The atomic force microscope (AFM), capable of examining growth patterns on surfaces at the highest resolution, is a tool that can demonstrate some of the key interactions.
To understand the mechanism, some knowledge of mineral scale precipitation is necessary.
We know that in order to form a scale deposit three conditions must be met; the solution must be supersaturated, nucleation sites must be available at the pipe surface, and contact/residence time must be adequate.
To prevent scale it is necessary to remove at least one of these preconditions.
Clearly contact time is not an alterable factor.
To be effective any device must therefore affect either the supersaturation value or the nucleation process.
The direct effect of the electronic device described above is on the nucleation process and in particular to enhance initial nucleation through the creation of new nucleation sites within the bulk fluid flow.
Crystal growth then occurs at these points of nucleation and not at the pipewall.
Suspended solids increase with a corresponding drop in the level of supersaturation, and these effects have been observed in the field.
The localised pH increase near the pipewall caused by hydroxyl radicals formed by electromechanical interactions is one mechanism that drives the changed nucleation characteristics.
A Lorenz force F is experienced by charged particles that flow through a field: F= qE + q (V x B) where q is the charge on the particle, E is the electric field vector, V is the particle velocity, and B the magnetic field vector.
Electronic devices operate at very small residual magnetic fields whereas magnets need high field strength (>1000gauss) for optimum performance.
The flow dependency of magnetic devices is explained by the velocity parameter, V, and E=0.
The flow non-dependency of electronic devices is explained by the fact that the magnetic component approaches zero, but the electric component is essentially constant.
This suggests the key performance parameter is the total value of the "Lorenz" force acting on the charged particles, rather than the individual magnetic and electric field vectors.
Studies by a Scalewatcher -Enigma R and D group have also shown that EWT has a significant effect on the Collision Factor and the Ion Kinetic Energy, increasing the number of collisions, increasing the collision energy, and thus increasing the nucleation points in the liquid flow.
As a consequence to the enhanced nucleation and precipitation of scaling minerals, it has been noted that previously supersaturated solutions become locally undersaturated (downstream), thus disturbing the equilibrium of existing scale deposits, which slowly dissolve.
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