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Non-Chemical Technologies for Scale and Hardness Control

Technology for improving energy efficiency through the removal or prevention of scale.

Abstract

The magnetic technology has been cited in the literature and investigated since the turn of the 19th century, when lodestones and naturally occurring magnetic mineral formations were used to decrease the formation of scale in cooking and laundry applications. Today, advances in magnetic and electrostatic scale control technologies have led to their becoming reliable energy savers in certain applications.

For example, magnetic or electrostatic scale control technologies can be used as a replacement for most water-softening equipment. Specifically, chemical softening (lime or lime-soda softening), ion exchange, and reverse osmosis, when used for the control of hardness, could potentially be replaced by non-chemical water conditioning technology. This would include applications both to cooling water treatment and boiler water treatment in once-through and recirculating systems.

The primary energy savings from this technology result from decrease in energy consumption in heating or cooling applications. This savings is associated with the prevention or removal of scale build-up on a heat exchange surface, where even a thin film can increase energy consumption by nearly 10%. Secondary energy savings can be attributed to reducing the pump load, or system pressure, required to move the water through a scale-free, unrestricted piping system.

This Federal Technology Alert provides information and procedures that a Federal energy manager needs to evaluate the cost-effectiveness of this technology. The process of magnetic or eletrostatic scale control and its energy savings and other benefits are explained. Guidelines are provided for appropriate application and installation. In addition, a hypothetical case study is presented to give the reader a sense of the actual costs and energy savings. A listing of current manufacturers and technology users is provided along with references for further reading.

About The Technology

The technology addressed in this FTA uses a magnetic or electrostatic field to alter the reaction between scale-forming ions in hard water. Hard water contains high levels of calcium, magnesium, and other divalent cations. When subjected to heating, the divalent ions form insoluble compounds with anions such as carbonate. These insoluble compounds have a much lower heat transfer capability than heat transfer surfaces such as metal. They are insulators. Thus additional fuel consumption would be required to transfer an equivalent amount of energy.

The magnetic technology has been cited in the literature and investigated since the turn of the 19th century, when lodestones or naturally occurring magnetic mineral formations were used to decrease the formation of scale in cooking and laundry applications. However, the availability of high-power, rare-earth element magnets has advanced the magnetic technology to the point where it is more reliable. Similar advances in materials science, such as the availability of ceramic electrodes and other durable dielectric materials, have allowed the electrostatic technology to also become more reliable.

The general operating principle for the magnetic technology is a result of the physics of interaction between a magnetic field and a moving electric charge, in this case in the form of an ion. When ions pass through the magnetic field, a force is exerted on each ion. The forces on ions of opposite charges are in opposite directions. The redirection of the particles tends to increase the frequency with which ions of opposite charge collide and combine to form a mineral precipitate, or insoluble compound. Since this reaction takes place in a low-temperature region of a heat exchange system, the scale formed is non-adherent. At the prevailing temperature conditions, this form is preferred over the adherent form, which attaches to heat exchange surfaces.

The operating principles for the electrostatic units are much different. Instead of causing the dissolved ions Federal Technology Alert - Non-Chemical Technologies for Scale and Hardness Control to come together and form non-adherent scale, a surface charge is imposed on the ions so that they repel instead of attract each other. Thus the two ions (positive and negative, or cations and anions, respectively) of a kind needed to form scale are never able to come close enough together to initiate the scale-forming reaction. The end result for a user is the same with either technology; scale formation on heat exchange surfaces is greatly reduced or eliminated.

Application Domain

These technologies can be used as a replacement for most water-softening equipment. Specifically, chemical softening (lime or lime-soda softening), ion exchange, and reverse osmosis (RO), when used for the control of hardness, can be replaced by the non-chemical water conditioning technology. This would include applications both to cooling water treatment and boiler water treatment, in once-through and recirculating systems. Other applications mentioned by the manufacturers include use on petroleum pipelines as a means of decreasing fouling caused by wax build-up, and the ability to inhibit biofouling and corrosion.

The magnetic technology is generally not applicable in situations where the hard water contains "appreciable" concentrations of iron. In this FTA, appreciable means a concentration requiring iron treatment or removal prior to use, on the order of parts per million or mg/L. The reason for this precaution is that the action of the magnetic field on the hardness-causing ions is very weak. Conversely, the action of the magnetic field on the iron ions is very strong, which interferes with the water conditioning action.

A search of the Thomas RegisterTM in conjunction with manufacturer contact yielded eleven manufacturers of magnetic, electromagnetic or electrostatic water conditioning equipment that fell within the scope of this investigation. The defined scope includes commercial- or industrial-type magnetic, electromagnetic or electrostatic devices marketed for scale control. Devices intended for home use, as well as other nonchemical means for scale control, such as reverse osmosis, are not within the extended scope of this FTA.

Exact numbers of units deployed by these manufacturers are virtually impossible to compile, as some of the manufacturers had been selling the technology for up to 40 years. One manufacturer claims as many as 1,000,000 units (estimated total of all manufacturers represented here) are installed in the field. Where not withheld by the manufacturer because of business sensitivity reasons, customer lists included both Federal and non-Federal installations. Those manufacturers who did withhold the customer list indicated a willingness to disclose customer contacts to legitimate prospective customers.

Literature provided by and discussions with manufacturers described a typical installation for a boiler water treatment scheme as including the device installed upstream of the boiler. Manufacturers vary in their preference of whether the device should be installed close to the water inlet or close to the boiler. Both locations have been documented as providing adequate performance. Generally, the preferred installation location for use with cooling towers or heat exchangers is upstream of the heat exchange location and upstream of the cooling tower. Downstream of the cooling tower but upstream of the heat source was also mentioned as a possible installation location, primarily for the use with chillers or other cooling equipment.

The primary caveat on installation of the magnetic technology is that high voltage (230V, 3-phase or above) power lines interfere with operation by imposing a second magnetic field on the water. (This is most noticeable when these electric power sources are installed within three feet of a magnetic device.) This second magnetic field most likely will not be aligned with the magnetic field of the device, thus introducing interference and reducing the effectiveness of the treatment. Installations near high voltage power lines are to be avoided if possible. Where avoidance is not possible, the installation of shielded equipment is recommended to achieve optimum operation. Some manufacturers also have limitations on direction of installation--vertical or horizontal--because of internal mechanical construction

Energy-Savings Mechanism

The primary energy savings result from a decrease in energy consumption in heating or cooling applications. This savings is associated with the prevention or removal of scale build-up on a heat exchange surface where even a thin film (1/32" or 0.8 mm) can increase energy consumption by nearly 10%. Example savings resulting from the removal of calcium-magnesium scales are shown in Table 1. A secondary energy savings can be attributed to reducing the pump load, or system pressure, required to move the water through a scale-free, unrestricted piping system.

Table 1. Example Increases in Energy Consumption
as a Function of Scale Thickness

As was discussed above, magnetic and electric fields interact with a resultant force generated in a direction perpendicular to the plane formed by the magnetic and electric field vectors. (See Figure 2 for an illustration.) This force acts on the current carrying entity, the ion. Positively charged particles will move in a direction in accord with the Right-hand Rule, where the electric and magnetic fields are represented by the fingers and the force by the thumb. Negatively charged particles will move in the opposite direction. This force is in addition to any mixing in the fluid due to turbulence.


Figure 2. Diagram Showing Positioning of Fields and Force

The result of these forces on the ions is that, in general, positive charged ions (calcium and magnesium, primarily) and negative charged ions (carbonate and sulfate, primarily) are directed toward each other with increased velocity. The increased velocity should result in an increase in the number of collisions between the particles, with the result being formation of insoluble particulate matter. Once a precipitate is formed, it serves as a foundation for further growth of the scale crystal. The treatment efficiency increases with increasing hardness since more ions are present in solution; thus each ion will need to travel a shorter distance before encountering an ion of opposite charge.

A similar reaction occurs at a heat exchange surface but the force on the ions results from the heat input to the water. Heat increases the motion of the water molecules, which in turn increases the motion of the ions, which then collide. In addition, scale exhibits an inverse solubility relationship with temperature, meaning that the solubility of the material decreases as temperature increases. Therefore, at the hottest point in a heat exchanger, the heat exchange surface, the scale is least soluble, and, furthermore due to thermally induced currents, the ions are most likely to collide nearest the surface. As above, the precipitate formed acts as a foundation for further crystal growth.

When the scale-forming reaction takes place within a heat exchanger, the mineral form of the most common scale is called calcite. Calcite is an adherent mineral that causes the build-up of scale on the heat exchange surface. When the reaction between positively charged and negatively charged ions occurs at low temperature, relative to a heat exchange surface, the mineral form is usually aragonite. Aragonite is much less adherent to heat exchange surfaces, and tends to form smaller-grained or softer-scale deposits, as opposed to the monolithic sheets of scale common on heat exchange surfaces.

These smaller-grained or softer-scale deposits are stable upon heating and can be carried throughout a heating or cooling system while causing little or no apparent damage. This transport property allows the mineral to be moved through a system to a place where it is convenient to collect and remove the solid precipitate. This may include removal with the wastewater in a once-through system, with the blowdown in a recirculating system, or from a device such as a filter, water/solids separator, sump or other device specifically introduced into the system to capture the precipitate.

Water savings are also possible in recirculating systems through the reduction in blowdown necessary. Blowdown is used to reduce or balance out the minerals and chemical concentrations within the system. If the chemical consumption for scale control is reduced, it may be possible to reduce blowdown also. However, the management of corrosion inhibitor and/or biocide build-up, and/or residual products or degradation by-products, may become the controlling factor in determining blowdown frequency and volume.

Other Benefits

Aside from the energy savings, other potential areas for savings exist. The first is elimination or significant reduction in the need for scale and hardness control chemicals. In a typical plant, this savings could be on the order of thousands of dollars each year when the cost of chemicals, labor and equipment is factored in. Second, periodic descaling of the heat exchange equipment is virtually eliminated. Thus process downtime, chemical usage, and labor requirements are eliminated. A third potential savings is from reductions in heat exchanger tube replacement due to failure. Failure of tubes due to scale build-up, and the resultant temperature rise across the heat exchange surface, will be eliminated or greatly reduced in proportion to the reduction in scale formation.

Variations

Devices are available in two installation variations and three operational variations. First to be discussed are the two installation variations: invasive and non-invasive. Invasive devices are those which have part or all of the operating equipment within the flow field. Therefore, these devices require the removal of a section of the pipe for insertion of the device. This, of course, necessitates an amount of time for the pipe to be out of service. Non-invasive devices are completely external to the pipe, and thus can be installed while the pipe is in operation. Figure 3 illustrates the two installation variations.

Figure 3. Illustration of Classes of Magnetic Devices by Installation Location

The operational variations have been mentioned above; illustrations of the latter two types are shown Figure 4:

• Magnetic, more correctly a permanent magnet
  
• Electromagnetic, where the magnetic field is generated via electromagnets
  
• Electrostatic, where an electric field is imposed on the water flow, which serves to attract or repel the ions and, in addition, generates a magnetic field.

Savings are expected to result from discontinuance of chemical consumption and decreased energy consumption (10% of process energy and all of the water treatment energy). Inspection will still occur.

Savings Potential

Energy savings can result from two areas. First is the reduction in fuel used in generating heat. Methods for calculating the fuel consumption were discussed above in the technology descriptions. The fuel consumption savings is simply the net difference, in this case estimated equal to 10% of the baseline fuel consumption. (This estimated savings was used to illustrate a case where there was a fairly uniform 1/16" thick layer of scale across a heat exchanger surface. Of course, it is realized that the scale layer, and therefore energy consumption, builds over time and is not an instantaneous effect.) This savings is also equal to the loss in heat transfer efficiency due to scale formation on the heat exchange surface.

Second is the energy savings resulting from decreased pressure drop within the heat exchanger. This is not quantified here, but could be quantified if the pressure drop through the current system was known, along with the energy characteristics of the pump so that reductions in pressure could be related to energy consumption.

Cost savings also result from reductions in chemical use. Chemical softening will be reduced, and likely eliminated, by the use of non-chemical treatment technologies. There will also be a corresponding energy decrease from the shutdown of chemical mixing equipment and water treatment equipment used in the softening process. The estimated chemical savings here was 480 tons per year and the corresponding electricity savings was 31,000 kWh per year.

Table 3 illustrates typical consumption data for the baseline and alternative and the potential annual costs savings. Not shown are water consumption and water discharge, which do not change between the alternatives. Capital cost for the alternative treatment system, estimated at $10,000 at the beginning of the 15-year analysis period, is not shown either. Fifteen years was chosen because it was typical of the life of field units.

Table 3. Annual Costs and Savings

Life-Cycle Cost

The full results of the BLCC computations are shown in Appendix B. A discussion of the BLCC software is given in Appendix A. The BLCC Comparative Economic Analysis is shown in Figure 5. Installation cost for the magnetic treatment device is estimated at $10,360, calculated as $10,000 for the device and $360 for design and installation labor. Operating costs for the technology are estimated at $2,088,000 per year versus costs of $2,320,635 per year for the conventional lime-softening technology, both exclusive of water consumption and discharge. Life-cycle costs for each of the technologies as calculated by the BLCC software are $27,524,500 for the magnetic technology versus $30,283,500 for the conventional technology. (This includes the cost of water and wastewater disposal of $2,605,292.) This represents a life-cycle cost savings of $2,759,000. The Simple Payback from BLCC is less than one year, and the Adjusted Internal Rate of Return is 50.66%.

Figure 5. Comparative BLCC Analysis

Manufacturers

The following is a listing of manufacturers of these technologies compiled from the Thomas Register and those who have contacted FEMP directly. It has been limited to U.S. manufacturers; foreign manufacturers or U.S. affiliates of foreign manufacturers were not included. No effort was made to locate and include manufacturers not listed in the Thomas Register. This listing does not purport to be complete, to indicate the right to practice the technology, or to reflect future market conditions.

Advanced Environmental Products
9450 Schulman #113
Dallas, TX 75243
214/340-1435
Fax: 214/344-2134

Aqua-Floe Inc.
Department T-94
6244 Frankford Avenue
Baltimore, MD 21206
800/368-2513
410/485-7600
Fax: 410/488-2030

Aqua Magnetics International, Inc.
915-B Harbor Lake Drive
Safety Harbor, FL 34695
813/447-2575
Fax: 813/726-8888

Conservonics
30555 Southfield Road #420
Southfield, MI 48076
801/540-3634
Fax: 810/716-7508

Descal-A-Matic Corp
4855-T Brookside Ct. Suite A
Norfolk, VA 23502
757-858-5593
Fax: 757/853-3321

Electrostatic Technologies Inc.
2223 Guinotte Avenue
Kansas City, MO 64120
816/842-0616
Fax: 816/842-9756

Enecon Corp.
125 Bayliss Road Suite 190
Mellville, NY 11747-3800
800/854-1374

Enertec Inc.
Department TR
306 Railroad Street
P.O. Box 85
Union City, MI 49094
517/741-5015
Fax: 517/741-3474

Hydrodynamics Corp.
1615 W. Abram Street #110
Arlington, TX 76013
817/277-6700
Fax: 817/277-2197

Magnatech Corp.
Superior Manufacturing Division
2015 S. Calhoun Street
P.O. Box 13543
Fort Wayne, IN 46868
800/692-1123
219/456-3596
Fax: 219/456-3598

Progressive Equipment Corp.
419 East 9th Street
Erie, PA 16503
814/452-4363
800/728-6395
Fax: 814/459-3094

Quantum Magnetic Systems Inc.
5224 Blanche Ave.
Cleveland, OH 44127
216/441-9670
Fax: 216/441-9677

Zeta Hydrometals Corporation
4565 S. Palo Verde Road, Suite 213
Tucson, AZ 85714
520/747-4550
888/785-9660
Fax: 520/747-4454

Who is Using the Technology

Federal Sites

Included here are but a few of the installations provided by the manufacturers. For a full listing the reader is advised to contact a manufacturer directly. Some manufacturers expressed concern about printing customer names in a public list such as this Federal Technology Alert but indicated they could provide such customer references to interested potential buyers. Most manufacturers specify having hundreds to almost 10,000 installations. Not all of these sites were contacted during the course of preparing this FTA.

• GSA, Suitland, MD
• National Aeronautics and Space Administration, multiple locations United States Coast Guard, multiple locations
• United States Air Force, Luke AFB, Phoenix, AZ
• United States Army Corps of Engineers, Sacramento District, Sacramento, CA
• United States Environmental Protection Agency, Andrew W. Breidenbach Environmental Research Center, Cincinnati, OH (Rich Koch and Bob Banner, Cleveland Telecommunications Corporation)
• United States Postal Service, multiple locations

Non-Federal Sites

• Arnold Printing, Cincinnati, OH (Hank Majeushi, 513/533-9600)
• Bethlehem Steel, multiple locations Chrysler, multiple locations
• Ford Motor Company, multiple locations
• General Electric, multiple facilities
• General Motors, multiple facilities
• Getty Center, Los Angeles, CA
• Inland Steel, 200 locations
• House of the Future, Ahwatukee, AZ (Arnold Roy, The Frank Lloyd Wright Foundation, 602/948- 6400)
• John Deere, multiple locations
• John Hancock Center, Chicago, IL
• LTV Steel, multiple locations
• Protective Coatings Inc. (Bob Bernadin and Ron Byers, 219/456-3596)
• National Steel, over 100 installations
• USX, multiple locations
• United States Playing Card Company, Cincinnati, OH (Tom Berens, 513/396-5700)

For Further Information

Associations

No trade associations exist that are specific to the non-chemical water treatment technology manufacturers. The following associations are general water quality associations.

American Water Works Association
6666 West Quincy Ave
Denver, CO 80235
303/794-7711

Cooling Tower Institute
P.O. Box 73383
Houston, TX 77273
713/583-4087

Water Quality Association
4151 Naperville Road
Lisle, IL 60532
708/505-0160

Consultants

Robert A. Marth
340 Central Avenue
Sunnyvale, CA 94086
408/746-0964
Fax: 408-737-0291

T. Craig Molden
Water Service Technology/NWI
P.O. Box 545 Michigan City, IN 46361
219/879-8425
Fax: 219/879-8852

User and Third Party Field Test Reports

The following references represent only a small sample of the published work on these technologies. The references here are intended to give the reader an indication of the history of scientific research on the topic as well as the sponsoring agencies and interested audiences.

Alleman, J. 1985. Quantitative Assessment of the Effectiveness of Permanent Magnet Water Conditioning Devices. Purdue University. Sponsored by and protocol by Water Quality Association.

American Petroleum Institute. 1985. Evaluation of the Principles of Magnetic Water Treatment, Publication 960.

Baker, J.S., and S.J. Judd. 1996. "Magnetic Amelioration of Scale Formation." Water Research, 30(2):247- 260.

Benson, R.F., B.B. Martin, and D.F. Martin. 1994. "Management of Scale Deposits by Diamagnetism. A Working Hypothesis." Journal Environmental Science and Health, A29(8):1553-1564.

Busch, K. W., M. A. Busch, D. H. Parker, R. E. Darling, and J. L. McAtee, Jr. 1986. "Studies of a Water Treatment Device That Uses Magnetic Fields," In Proceedings Corrosion/85, Boston MA.

Dirks, J.A., and L.E. Wrench. 1993. "Facility Energy Decision Screening (FEDS) Software System." PNLSA- 22780. In Proceedings of the Energy and Environmental Congress. Minneapolis, Minnesota, August 4- 5, 1993.

Fryer, L. 1995. "Magnetic Water Treatment A Coming Attraction?" E-Source, TU-95-7

Gruber and Carda. 1981. Performance Analysis of Permanent Magnet Type Water Treatment Devices. South Dakota School of Mines and Technology. Sponsored by and protocol by Water Quality Association.

Hibben, S.G. 1973. Magnetic Treatment of Water. Advanced Research Projects Agency of the Department of Defense.

Marth, R.A. 1997. A Scientific Definition of the Magnetic Treatment of Water: Its Subsequent Use in Preventing Scale Formation and Removing Scale. Research Conducted for Descal-A-Matic Corporation.

Parsons, S.A., Bao-Lung Wang, S.J. Judd, and T. Stephenson. 1997. "Magnetic Treatment of Calcium Carbonate Scale -- Effect of pH Control." Water Research, 31(2): 339-342.

Quinn, C.J., T.C. Molden, and C.W. Sanderson. 1996. "Nonchemical Approach to Hard Water Scale, Corrosion and White Rust Control." In Proceedings Iron and Steel Engineer, Chicago IL, September 30, 1996.

Reimers, R.S., P. S. DeKernion, and D. B. Leftwich. 1979. "Sonics and Electrostatics - An Innovative Approach to Water and Waste Treatment." In Proceedings Water Reuse Symposium, Volume 2. American Water Works Research Association Research Evaluation, Denver, CO.

Rubin, A.J. 1973. To Determine if Magnetic Water Treatment is Effective in Preventing Scale. The Ohio State University, Columbus, OH.

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