Power plants – Motive fluid energized by externally applied heat – Process of power production or system operation
Reexamination Certificate
1999-02-11
2001-02-13
Nguyen, Hoang (Department: 3748)
Power plants
Motive fluid energized by externally applied heat
Process of power production or system operation
C060S673000
Reexamination Certificate
active
06185940
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to applications of energy in concentrated brine, and, more particularly, to the use of concentrated brine to drive osmosis processes for generating electricity and producing fresh water.
BACKGROUND OF THE INVENTION
Osmosis is a process wherein fluid moves through a semipermeable membrane in an attempt to equalize the chemical potential across the membrane. This process most commonly occurs when fluids having different concentrations of brine, e.g., salt solutions, are placed on opposite sides of the semipermeable membrane. A resulting potential energy, osmotic pressure, is produced that can be converted to mechanical and electrical energy.
U.S. Pat. No. 3,978,344, issued Aug. 31, 1976, to Jellinek, teaches a body of salt water and a body of fresh water, both at ambient pressure, in contact with opposite sides of a semipermeable membrane. Fresh water passes through the membrane with a concomitant build-up of osmotic pressure that causes salt water to be ejected through an orifice and directed against turbine blades to produce mechanical or electrical energy. The salt water and fresh water adjacent the membrane surfaces are simply replaced from adjacent fluid reservoirs.
U.S. Pat. No. 4,283,913, issued Aug. 18, 1981, to Loeb, teaches a low pressure fluid with little or no brine concentration and a pressurized brine solution on opposite side of a semipermeable membrane where the movement of fluid across the membrane forces the brine solution to flow through a turbine to generate mechanical or electrical energy. The depressurized brine solution is then passed to a saturated solar pond where solar energy acts to separate the fluid therein into a vertical gradient of concentrations so that high concentration brine may be removed at one location and low concentration brine at another position. Now the high concentration brine must be pressurized by a relatively high pressure pump for return to the membrane chamber with a concomitant consumption of electrical or mechanical energy and resulting loss of overall process efficiency.
Various objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
SUMMARY OF THE INVENTION
The invention embodied and broadly described herein is directed to an apparatus and method for the generation of energy and, optionally, for producing fresh water using osmotic processes that are driven by energy embodied in brine that is concentrated by the evaporation of water. A first water supply contacts a first side of an osmotic membrane while a high pressure concentrated brine solution contacts a second side of the osmotic membrane where the brine solution has a salt concentration effective for fresh water to flow from the first water supply into the brine solution by osmotic pressure across the membrane. A first mass transfer unit defines a first volume and a second volume, where the first and second volumes are separated by a first movable interface. A concentrator uses dry air to concentrate a dilute brine solution to a concentrated brine solution.
A first piping system is connected to direct the high-pressure concentrated brine solution across the second face of the membrane and has first and second outlets. A motor is connected to the first outlet of the first piping system and has an outlet connected to the concentrator. A first three-way valve connects the first volume of the first mass transfer unit to the first piping system or to the concentrator. A second piping system is connected to the concentrator for returning concentrated brine from the concentrator to the second volume of the first mass transfer unit. A third piping system is connected to the first piping system for moving concentrated brine from the second volume of the first mass transfer unit to the first piping system. A second three-way valve connects the second volume of the first mass transfer unit to the second or third piping systems for alternately receiving concentrated brine from the concentrator and delivering the concentrated brine to the osmotic chamber to replenish the brine that has been diluted by transfer of fresh water across the osmotic membrane.
REFERENCES:
patent: 3906250 (1975-09-01), Loeb
patent: 3978344 (1976-08-01), Jellinek
patent: 4171409 (1979-10-01), Loeb
patent: 4193267 (1980-03-01), Loeb
patent: 4283913 (1981-08-01), Loeb
patent: 4617800 (1986-10-01), Assaf
patent: 5622605 (1997-04-01), Simpson et al.
patent: 5645693 (1997-07-01), Göde
patent: 5755102 (1998-05-01), Assaf et al.
patent: 5784866 (1998-07-01), Prueitt
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