Apparatus for the separation of ions from solution

Abstract

Abstract An ionized solution or electrolyte, such as sea water, is caused to flow through a conduit while passing through a magnetic field produced between magnets of opposite polarity disposed in spaced relationship adjacent opposite wall portions of the conduit. Extending between these magnets are two spaced opposite conduit wall portions of electrically non-conducting porous material, such as porous ceramic material, through the pores of which the positive and negative ions in a solution such as sea water can pass. When subjected to the magnetic field extending between the magnets, the positive and negative ions are deflected laterally away from each other in opposite directions toward the porous walls, and are expelled from the conduit through the pores. The opposite but approximately parallel flow of positive and negative ions through this transverse magnetic field generates an electric current density, a very large percentage of which passes through the faces of the conduit''s porous walls. The magnitude of the current density flowing out from the pores of the conduit and into the external medium is a measure of the relative concentration of salt water undergoing desalinization by passing constituent ions (in this case from a salt water solution) through the conduit. If there is no measurable current density at a station downstream along the conduit adjacent the external side of its porous walls, the deionized water leaving the outlet orifice of the conduit is essentially free from salts. To prevent external ions from entering the conduit through its porous walls by diffusion or otherwise, fluid adjacent the porous walls inside and outside the conduit should maintain parallel flow. An ionized solution, such as sea water, flowing past the pores outside the conduit faster than the partially deionized solution inside the conduit will produce a Venturi suction which draws off some of the processed solution of lowered salinity through the pores into the outside flow stream. This forms a thin boundary layer of lowered salinity along the external porous surface of the conduit which assists in preventing the external ion intrusion mentioned above. An internal over-pressure sustained by a dynamic flow pressure along the external porous surface balances any hydrostatic pressure tending to force ions back into the conduit. To minimize the outward expansion of the external magnetic field generated by the device and its components, the magnets on opposite sides of the conduit are preferably arranged in a series with alternating polarities on each side. Ferromagnetic materials with high magnetic permeability, such as soft silicon steel, are used to provide an easy magnetic flux path for an otherwise open magnetic circuit external to the conduit. Minimizing the external magnetic field is desirable because this field acts to drive ions back into the device and is a source of inefficiency during operation. The magnets are prEferably permanent magnets but may alternatively be electromagnets. A modification of FIG. 3 (FIGS. 5 and 6) provides a barrier between the bodies of flowing electrolyte within the outer conduit and also provides gas escape ports in the upper wall of the outer conduit. The barrier is composed of electrically conducting walls separated from one another by an electrically insulating layer, and conductors electrically connected to these walls carry off current generated in operation and which may be used to actuate electrical devices in external circuits.

Inventors

• 👤 D Ustick

Bibliographic Details