Reference

References

Magnetic Water Treatment
Reprint of article from Pollution Engineering
By: Jennifer Brower
Posted: February 1, 2005

Pollution-free, non-chemical, magnetic water treatment technology is rapidly becoming an accepted method of controlling lime/scale and corrosion in HVAC and other heat-transferring, water-related equipment. Applications are numerous, including boilers, cooling towers, heat exchangers, coffee makers, dishwashers and many other types of water-using equipment.

Case histories of the success of magnetically treated water date back to 1803. The magnetic effect of certain minerals in water was first recorded over 200 years ago when there was a notable difference in the texture of the mineral accumulation on the sides and bottoms of soup and laundry kettles. Large stones were placed in the bottom of these cast iron kettles, which were suspended above an open fire, to keep them from swinging in windy weather. Reportedly, two of five kettles – all made of the same cast iron material – did not have the hard, rock-like scale formation, but instead had a soft, powdery substance that was easily brushed off. It was later found that two of the five rocks used to stabilize the five kettles in high winds were lodestones (natural magnetic rocks) that obviously prevented the calcium carbonate from forming a hard calcite scale.

Magnetic de-scaling technology has evolved considerably since using lodestones. From the early 1800s to the 1950s, many attempts were made to utilize the highly technical, yet inexpensive, methods of treating water; nevertheless, most proved to be unsuccessful. However, in the last forty years, hundreds of thousands of in-line magnetic systems have been installed and proven to be very successful. Even though non-chemical systems were highly controversial as to understanding how they worked, the question of "do they work" has been put to rest.

The answer to how they work is much simpler than many might think. Water-borne minerals are usually in solution. However, when these minerals are subjected to heat change, they have a tendency to precipitate out of solution and form a hard, brittle scale on heat transfer surfaces in water-using equipment. This buildup of scale increases resistance to heat transfer and thus, has a detrimental impact on thermal performance. This increases energy costs and maintenance problems, reduces efficiency, and shortens the lifespan of water-using equipment.

Magnetic systems treat water by passing it through a multi-pole, multi-reversing polarity magnetic field. Liquid first flows through a succession of alternating magnetic fields perpendicular to the lines of force. The dipolar movements of the molecules of dissolved solids and water molecules are affected in such a way that at the instant of crystal formation, the crystal form is divided into thin layers and the ions align according to a single magnetic axis. The magnetic field then influences the production of a much greater number of nuclei. Hence, the solids precipitate as much finer crystals, which tend to remain separated because of the excess similar charge (higher reactivity) that each crystal has acquired. The calcium carbonate powder is now in a sludge form and can be easily maintained by normal draining, bleed-off or blow-down procedures. The treatment also gradually reduces existing scale buildup in the system.

Magnetic water treatment is not a cure-all. However, when a properly designed magnetic water system is correctly sized, installed and maintained on a cooling tower or any water-using equipment within its limitations, hard water scale and corrosion can be controlled at least as effectively as any other method presently being used in the industry.

Engineers looking for both a way to control scale without the cost of monthly chemicals and a way to eliminate the necessity of chemical disposal can opt for magnetic water treatment. This technology is designed to eliminate the chemicals for lime/scale and corrosion control, and reduce bleed requirements in cooling tower applications while increasing overall efficiency in water-using vessels.

HVAC use (cooling towers, boilers, heat exchangers, etc.) makes up the majority of the non-chemical water treatment users list. However, restaurants, apartment complexes, car washes, schools and anyone using heat transferring vessels that have a potential of lime/scale buildup would be benefited by this method of treatment. Magnetic systems range from one-quarter inch compression fitting connections starting at one gallon per hour up to ninety inch flanged connections at fifty thousand gallons per minute, all controlling lime/scale the same way, but at different flow rates and under different conditions.

The following are the most recognized benefits of magnetic water treatment for various water-using equipment:
• Prevents pollution
• Reduces energy
• Conserves water
• Saves time and money
• Lengthens service life of existing fluid movement equipment
• Eliminates existing chemical cost to inhibit scale
• Reduces the need for periodic acid cleaning
• Increases protection against corrosion within the system
• Eliminates continual operating cost as compared to chemical systems

A magnetic water treatment system is usually a one-time purchase with a very good return on investment within a short period of time. The following shows average payback periods for several magnetic systems installed on six different types of applications, by eliminating the cost of chemicals only:

• Process steam boilers = six to nine months
• Process hot water boiler = eight to12 months
• Steam heating boiler = 15 to 18 months
• Hot water heating = 24 to 36 months
• Cooling tower process = 10 to 12 months
• Cooling tower comfort air = one to two seasons (depending on months of year it is used)

These payback periods vary due to the quality of the water, once-through or returned-as-condensate recirculating systems, as well as the effectiveness and cost of the previous chemical treatment.

A recent research project sponsored by the American Society of Heating, Refrigerating and Air-conditioning Engineers titled, Efficiency of Physical Water Treatment in Controlling Calcium Scale in Recirculating Open Cooling Water System, and conducted at Drexel University, Philadelphia, under the direction of Dr. Young Cho, confirmed positive results for lime/scale control using this technology. The full report (RP-1155) can be found online at www.ashrae.org.

Public awareness of today's pollution will encourage industry to comply with more stringent regulations. Viable methods to control lime/scale and corrosion, which are widely available today, will prevent the use of hazardous chemicals that continue to contaminate waterways and pollute the air. PE