Permanent magnets for water-scale prevention

Abstract

Anti-scale magnetic treatment (AMT) is discussed with the emphasis on the construction of magnetic devices and the mechanism of AMT influence on scale formation. Two field cases are reported of mineral-fouling reduction during water heating by using permanent magnets. Instead of hard encrustation on the heated surfaces a powdery deposit was formed because of modified crystal morphology (observed by X-ray powder diffractometry and scanning-electron microscopy). In order to find a proper design for magnets regarding the influencing parameters (a magnetic-field distribution with alternating lines orthogonal to the water-flow and minimal density peaks 0.2 T), cost-effective for actual water-flow capacities, several models with NdFeB magnets were simulated by the finite-element method using the OPERA 15R1 computational program. Two optimized models are presented for moderate capacities: a model with a rectangular gap (a two-row set of rectangular magnets) for capacities from 0.5 m 3 /h to 3 m 3 /h, and a model with annular gap (annular magnets on a pipe and disk magnets within a cylindrical kernel) for 3.5 m 3 /h to 5.5 m 3 /h.

Industrial Cooling Systems and Antibiofouling Strategies: A Comprehensive Review

“…The application of the magnetic field to the walls of these pipes magnetized the circulating water and eliminated the mineral deposits. These observations corroborate with several studies that use the magnetic field to reduce salt scale on surfaces, consolidating the use of this method in industrial water treatment as an antifouling strategy. ,− …”

Advanced Antiscaling Interfacial Materials toward Highly Efficient Heat Energy Transfer

“…[18] To reduce or delay the onset of scale formation, current methods mainly rely on the mechanical techniques, chemical strategies, or their combinations. [19] Generally, the mechanical techniques are based on physical removal, magnetic field, [18,20,21] electronic field, [22,23] and ultrasound. [24,25] Moreover, chemical strategies mainly depend on metal ions [26] and chemical additives [27][28][29] that can shift the precipitation equilibrium curve or act as inhibitors that change the crystallization kinetics.…”

Rare Earth Magnets and Limescale: Analysis of Magnetic Water Treatment Using a Dynamic Scale Rig

“…Scale deposition in process pipelines reduces the flow rate and heat transfer efficiency, leading to increased costs due to plant shut down for cleaning and maintenance. 1 Scaling can also lead to equipment failure and increased energy costs. 2 Many water treatment techniques exist that claim to reduce, or even eliminate, scale formation in industrial water systems.…”

“…2,4,15−17 The literature suggests that the effectiveness of the magnetic treatment depends on numerous parameters such as temperature, 4 pH, 5,18,19 flow rate/residence time, 3,5,7,20 type of scalant, 1,21 concentration, 5,19 and magnetic inten-sity. 1,5,22 The main findings have been that a magnetic field increases the rate of precipitation, 4 delays precipitation, 9 or promotes bulk precipitation. 18,21,23,24 These discrepancies can possibly be attributed to the use of different modes of producing a magnetic field, that is, non-standard techniques, or variations in water composition and operating procedures.…”

“…Calcium scaling, such as the formation of limescale, is a significant concern in industrial water systems. Scale deposition in process pipelines reduces the flow rate and heat transfer efficiency, leading to increased costs due to plant shut down for cleaning and maintenance . Scaling can also lead to equipment failure and increased energy costs .…”