Industrial water purification and desalination

Abstract

This invention relates to the field of water purification and desalination. In particular, embodiments of the invention relate to systems and methods of removing essentially all of a broad spectrum of impurities from water in an automated industrial process that requires minimal cleaning or maintenance during the course of several months to several years, with relatively high yields of product water per unit of input water, flexibility with respect to energy sources, compact design with a low industrial foot-print, the ability to recover valuable by-products, and ultra-low energy requirements.

What is claimed is: 
     
         1 . A water purification and desalination system comprising a pre-treatment section and a desalination section, wherein the pre-treatment permanently removes scale-forming compounds while yielding valuable by-products and CO 2  sequestration, and wherein the desalination section permits continuous operation of the purification and desalination without requiring user intervention or cleaning, and wherein the system is capable of removing, from a contaminated water sample, a plurality of contaminant types selected from the group consisting of: microbiological contaminants, radiological contaminants, metals, salts, volatile organics, and non-volatile organics, while recovering the energy of distillation multiple times, and wherein the system's energy source is selected from the group consisting of: electricity, geothermal energy, solar energy, the combustion of oil, hydrocarbons, or natural gas, or waste heat. 
     
     
         2 . The method of  claim 1 , wherein removal of scale-forming compounds from an aqueous solution comprises:
 adding at least one ion to the solution in a stoichiometric amount sufficient to cause the precipitation of a first scale-forming compound at an alkaline pH;   adjusting the pH of the solution to an alkaline pH, thereby precipitating the first scale-forming compound;   removing the first scale-forming compound from the solution;   adding another ion to the solution while adjusting pH to an alkaline pH to cause the precipitation of other scale-forming compounds; and   removing other scale-forming compounds from the solution.   
     
     
         3 . The method of  claim 2 , wherein the first ion is selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, and similar hydroxides. 
     
     
         4 . The method of  claim 2 , wherein the pH is adjusted to between 10.5 and 11.0 
     
     
         5 . The method of  claim 2 , wherein the second ion is a carbonate or bicarbonate ion. 
     
     
         6 . The method of  claim 2 , wherein the second ion is a divalent cation is a Ca 2+  or Mg 2+  ion. 
     
     
         7 . The method of  claim 6 , wherein the stoichiometric amount is sufficient to substitute the divalent cation for a divalent cation selected from the group consisting of barium, cadmium, cobalt, iron, lead, manganese, nickel, strontium, and zinc in the first scale-forming compound. 
     
     
         8 . The method of  claim 6 , wherein the stoichiometric amount is sufficient to substitute the divalent cation for a trivalent cation selected from the group consisting of aluminum and neodymium in the first scale-forming compound. 
     
     
         9 . The method of  claim 5 , wherein adding a second ion comprises sparging the solution with CO 2  gas. 
     
     
         10 . The method of  claim 9 , wherein the CO 2  is atmospheric CO 2 . 
     
     
         11 . The method of  claim 5 , wherein adding a second ion comprises adding to the solution a soluble bicarbonate ion selected from the group consisting of sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate. 
     
     
         12 . The method of  claim 2 , wherein the second precipitation is carried out at a pH of between 9.8 and 10.0. 
     
     
         13 . The method of  claim 2 , wherein removing the first scale-forming compound comprises at least one step selected from the group consisting of filtration, sedimentation, and centrifuging. 
     
     
         14 . The method of  claim 2 , wherein the second scale-forming compound comprises an insoluble carbonate compound. 
     
     
         15 . The method of  claim 2 , wherein removing the second scale-forming compound comprises at least one step selected from the group consisting of filtration, sedimentation, and centrifuging. 
     
     
         16 . The method of  claim 2 , additionally comprising removing contaminants from the solution prior to adding at least one ion. 
     
     
         17 . The method of  claim 16 , wherein the contaminants are selected from the group consisting of solid particles and hydrocarbon droplets. 
     
     
         18 . The method of  claim 16 , wherein the aqueous solution is selected from the group consisting of tap water, contaminated aqueous solutions, seawater, and saline brines contaminated with hydrocarbons. 
     
     
         19 . A method of obtaining scale-forming compounds, comprising:
 providing an aqueous solution;   carrying out the method of  claim 2 ;   recovering the first scale-forming compound; and   recovering the second scale-forming compound.   
     
     
         20 . The method of  claim 19 , wherein the first and second scale-forming compounds are selected from the group of compounds listed in Table 4. 
     
     
         21 . A method of sequestering atmospheric CO 2 , comprising:
 providing an aqueous solution containing at least one ion capable of forming a CO 2 -sequestering compound in the presence of carbonate ion;   adding carbonate ions to the solution in a stoichiometric amount sufficient to cause the precipitation of the CO 2 -sequestering compound at an alkaline pH;   adjusting the pH of the solution to an alkaline pH, thereby precipitating the CO 2 -sequestering compound; and   removing the CO 2 -sequestering compound from the solution,   wherein adding carbonate ions comprises adding atmospheric CO 2  to the solution, and wherein the atmospheric CO 2  is sequestered in the CO 2 -sequestering compound.   
     
     
         22 . The method of  claim 21 , wherein the alkaline pH is a pH of approximately 9.2 or greater. 
     
     
         23 . The method of  claim 21 , wherein the CO 2 -sequestering compound is selected from the group consisting of CaCO 3 , BaCO 3 , SrCO 3 , MgCO 3 , and similar carbonates. 
     
     
         24 . The method of  claim 21 , wherein removing the CO 2 -sequestering compound comprises at least one step selected from the group consisting of filtration, sedimentation, and centrifuging. 
     
     
         25 . An apparatus for removing a scale-forming compound from an aqueous solution, comprising:
 an inlet for the aqueous solution;   a source of caustic solution for pH adjustment, selected from the group consisting of NaOH, KOH, Ca(OH) 2 , and similar hydroxides;   a first tank in fluid communication with the inlet and the caustic solution;   a filter in fluid communication with said first tank, wherein said filter is adapted to separate a first scale-forming compound from the solution in said first tank;   a source of CO 2  gas;   a source of a pH-raising agent, which can be in fluid communication with said source of caustic solution;   a second tank in fluid communication with said source of a pH-raising agent, said source of CO 2  gas, and said first tank; and   a filter in fluid communication with said second tank, wherein said filter is adapted to separate a second scale-forming compound from the solution in said second tank   
     
     
         26 . The system of  claim 1 , wherein the desalination system comprises an inlet, a preheater, a degasser, a plurality of evaporation chambers, demisters, heat pipes, and product condensers, a waste outlet, multiple product outlets, a heating chamber, and a control system, wherein the heat of condensation is recovered and reused for additional evaporation, such that water purified in the system has levels of all contaminant types below the levels shown in Table 1, when the contaminated water has levels of the contaminant types that are up to 25, 50, 100, or 1,000 times greater than the levels shown in Table 1. 
     
     
         27 . The system of  claim 26 , wherein the volume of water produced is between about 20% and about 99% of a volume of input water. 
     
     
         28 . The system of  claim 26 , wherein the system does not require cleaning through periods of use of at least about two months, one year, five years, or more. 
     
     
         29 . The system of  claim 26 , further comprising an inlet switch to regulate flow of water through the inlet. 
     
     
         30 . The system of  claim 29 , wherein the switch comprises a mechanism selected from the group consisting of: a solenoid, a valve, and an aperture. 
     
     
         31 . The system of  claim 29 , wherein the inlet switch is controlled by the control system. 
     
     
         32 . The system of  claim 1 , further comprising a shutdown control. 
     
     
         33 . The system of  claim 32 , wherein the shutdown control is selected from the group consisting of: a manual control, a flood control, a condenser tank capacity control, and an evaporation chamber capacity control. 
     
     
         34 . The system of  claim 32 , wherein the control system controls the inlet based upon feedback from at least one detection method selected from the group consisting of: a temperature sensor in a boiler, a condenser tank float, and a flood detector. 
     
     
         35 . The system of  claim 31 , wherein the control system controls the switch based upon feedback from the pre-treatment and desalination system. 
     
     
         36 . The system of  claim 1 , further comprising a flow controller. 
     
     
         37 . The system of  claim 36 , wherein the flow controller comprises a pressure regulator. 
     
     
         38 . The system of  claim 37 , wherein the pressure regulator maintains water pressure between about 0 kPa and 250 kPa (0 to 36 psi). 
     
     
         39 . The system of  claim 26 , wherein water exiting the preheating chamber has a temperature of at least about 96° C. 
     
     
         40 . The system of  claim 26 , wherein the degasser is in a substantially vertical orientation, having an upper end and a lower end. 
     
     
         41 . The system of  claim 40 , wherein heated water from the preheating chamber enters the degasser proximate to the upper end. 
     
     
         42 . The system of  claim 40 , wherein the heated water exits the degasser proximate to the lower end. 
     
     
         43 . The system of  claim 26 , wherein steam from the evaporation chamber enters the degas ser proximate to the lower end. 
     
     
         44 . The system of  claim 43 , wherein the steam exits the degasser proximate to the upper end. 
     
     
         45 . The system of  claim 40 , wherein the degasser comprises a matrix adapted to facilitate the mixing of water and steam. 
     
     
         46 . The system of  claim 45 , wherein the matrix comprises substantially spherical particles. 
     
     
         47 . The system of  claim 45 , wherein the matrix comprises non-spherical particles. 
     
     
         48 . The system of  claim 45 , wherein the matrix comprises particles having a size selected to permit uniform packing within the degasser. 
     
     
         49 . The system of  claim 45 , wherein the matrix comprises particles of distinct sizes, wherein the particles are arranged in the degasser in a size gradient. 
     
     
         50 . The system of  claim 42 , wherein water exiting the degasser is substantially free of organics and volatile gasses. 
     
     
         51 . The system of  claim 26 , wherein the evaporation chambers include a plurality of heat pipes delivering heat that is transferred from lower condenser chambers. 
     
     
         52 . The system of  claim 51 , wherein the evaporation chamber further comprises a drain, and wherein the drain is at or about the middle of the chamber. 
     
     
         53 . The system of  claim 26 , the heating chamber further comprising electric heating elements, gas or oil burners, or heat pipes that transfer heat from waste heat sources, and wherein the heating chamber is adjacent to the bottom portion of the evaporation chamber. 
     
     
         54 . The system of  claim 26 , wherein the demister is positioned proximate to an upper surface of the evaporation chamber. 
     
     
         55 . The system of  claim 26 , wherein steam from the evaporation chamber enters the demister under pressure. 
     
     
         56 . The system of  claim 26 , wherein the evaporation chamber prevents condensed droplets from entering the demister by means of baffle guards and metal grooves. 
     
     
         57 . The system of  claim 54 , wherein the demister control parameter comprises at least one parameter selected from the group consisting of: a recessed position of a clean steam outlet, a pressure differential across the demister, a resistance to flow of a steam inlet, and a resistance to flow of a steam outlet. 
     
     
         58 . The system of  claim 26 , further comprising heat pipes for cooling the condenser product. 
     
     
         59 . The system of  claim 26 , wherein product water exits the product condensers through the product outlets. 
     
     
         60 . The system of  claim 26 , wherein waste water exits the system through the waste outlet. 
     
     
         61 . A method of purifying and desalinating water, comprising the steps of:
 providing a source of inlet water comprising at least one contaminant in a first concentration;   modifying the pH of the inlet water to cause precipitation of insoluble hydroxides and separating the precipitates from the incoming water;   adding a source of carbonate ions and modifying the pH to cause precipitation of insoluble carbonates and separating the precipitates from the incoming water;   passing the descaled pre-treated water through a preheating chamber capable of raising the temperature of the inlet water above 90° C.;   removing essentially all organics, volatiles, and gasses from the inlet water by counterflowing the inlet water against an opposite directional flow of a gas in a degasser;   maintaining the water in an evaporation chamber for an average residence time of between 1 and 90 minutes or longer under conditions that permit the formation of steam;   discharging steam from the evaporation chamber to a demister;   separating clean steam from contaminant-containing waste in the demister;   condensing the clean steam to yield purified water, comprising the at least one contaminant in a second concentration, wherein the second concentration is lower than the first concentration;   recovering and transferring heat from a condenser chamber into an upper boiling or preheating chamber, such that the amount of heat recovered is at least 50%, 60%, 70%, 80%, 90%, or more of the heat of condensation;   repeating the evaporation, condensation, and demisting operations multiple times in order to re-use the energy while maximizing clean water production.   
     
     
         62 . The method of  claim 61 , wherein the at least one contaminant is selected from the group consisting of: microorganisms, radionuclides, salts, organics, and disinfection by-products, as listed in Table 3; and wherein the second concentration is not greater than the concentration shown in Table 3, and wherein the first concentration is at least about 10 times the second concentration. 
     
     
         63 . The method of  claim 61 , wherein the stacked arrangement of boilers, condensers, and preheater is enclosed in a metal shell, with perforated plates that separate the boiling and condenser chambers. 
     
     
         64 . The method of  claim 61 , wherein the perforated plates allow the passage of heat pipes, the degasser, demisters, brine overflow tubes, and waste stream tubes. 
     
     
         65 . The method of  claim 61 , wherein the boilers, preheaters, and heat pipes are constructed from non-corrosive materials, such as titanium alloys or polymer-coated metals.