Abstract:
Apparatus and method for extracting water from air containing water vapor. A feed air assembly supplies air containing water vapor to a diff-user assembly in a reactive tank containing a reagent, preferably sulfuric acid, which absorbs the water vapor from the feed air. The reactive tank vents the dried air. A reagent solution line transmits reagent solution from the reactive tank to a recovery tank. A vacuum pump evaporates concentrated water vapor from the recovery tank and an extraction energy exchanger condenses the concentrated water vapor to liquid water.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention is in the field of apparatuses and methods for the extraction of water from air and in particular in the field of apparatuses for the extraction of liquid water from air containing water vapor through the use of a chemical reagent.  
       BACKGROUND OF THE INVENTION  
       [0002]     In many settings and geographical areas, a scarcity of water, and, in particular a scarcity of potable water, results in the consideration of many alternatives for the development of sources of water. Air containing water vapor is one such source.  
         [0003]     Even relatively dry desert air having a relative humidity of ten percent or less is a potential source for a huge quantity of water. The principal challenges that removing water from air with conventional technology presents are the large quantity of air that must be processed and the high energy requirements for condensing the water vapor. The heat of cooling and the heat of vaporization must be extracted from the air in order to condense the water vapor. The conventional approach is to pass the air through a heat exchanger which is cooled by the circulation of a refrigerant. With the relatively low concentration of water vapor in dryer settings where extraction of water from air is more likely to be considered, the low concentration results in the consumption of large amounts of energy for air handling and condensation.  
         [0004]     It is an objective of the present invention to provide an apparatus and method for increasing the efficiency and decreasing the energy requirements for water extraction from air containing water vapor.  
         [0005]     It is a further objective of the present invention to provide an apparatus and method for the extraction of water from air containing water vapor through the use of a chemical reagent to effect an increase in the concentration of water vapor.  
         [0006]     It is a still further objective of the present invention to provide an apparatus and method for the extraction of water from air containing water vapor that accommodates the use of waste heat or the use of direct heat from a solar collector or other sources for a portion of the energy required for the extraction process.  
         [0007]     It is a still further objective of the present invention to provide an apparatus and method for the extraction of potable water from raw water through the use of a chemical reagent and a vacuum to produce concentrated water vapor for condensation to potable water.  
       SUMMARY OF THE INVENTION  
       [0008]     For preferred embodiments, pressurized feed air from any source of air, including ambient atmosphere, containing water vapor is supplied to a reactive chamber containing a reagent, preferably sulfuric acid. The water vapor is absorbed from the pressurized feed air by reaction with the reagent and spent air with most of the water removed is discharged to atmosphere. Reagent solution is transmitted to a recovery chamber where concentrated water vapor is extracted from the reagent solution which is heated by recovery heat supplied from an energy source. The concentrated water vapor is extracted in a concentrated vapor zone created by a vacuum pump, which also pressurizes concentrated water vapor for an extraction energy exchanger which discharges extracted water. Heat of cooling and vaporization is extracted from the extraction energy exchanger by a heat exchange device. Concentrated reagent is re-circulated from the recovery chamber to the reactive chamber. The inventor prefers sulfuric acid as the reagent for the reactive chamber, because of its high water absorption capability, high vaporization temperature, high heat of vaporization, and relatively low cost.  
         [0009]     For preferred embodiments, feed air from the ambient atmosphere is pulled into an air intake and is pressurized by intake blowers. Pressurized feed air is transmitted by a feed pipe from the intake blowers to a diffuser assembly which diffuses, distributes and mixes diffused feed air with reagent in a reactive chamber. Spent air, which is the diffused feed air with most of the water content of the feed air removed, is released from a reactive chamber vent. The spent air will generally have a relative humidity of less than one percent. The diffuser assembly is preferably located near the bottom of the reactive chamber. As an alternative to a diffuser assembly, mechanical mixing or other diffusion means for diffusing, mixing and distributing the pressurized feed air in the reactive chamber can be used. Reagent solution is transmitted to the reagent recovery chamber by a reactive chamber feed line.  
         [0010]     A recovery vacuum pump which is connected to a concentrated vapor zone by a vacuum pipe imposes a vacuum on the recovery chamber liquid surface, which results in an accelerated vaporization rate for the water in the reagent solution. The inventor has found that a temperature ranging between 180° Fahrenheit and 200° Fahrenheit for the recovery chamber reagent solution is preferred for optimizing the vaporization of water from the reagent solution in the reagent recovery chamber, if sulfuric acid is used for the reagent.  
         [0011]     A recovery chamber temperature sensor is used to activate a recovery chamber heat assembly which includes a recovery chamber temperature control pump which pumps reagent solution from the recovery chamber by a recovery heat line through a recovery heat exchanger. The temperature sensor can also be used to control the rate of supply of recovery heat by a heat supply line from an energy source. The temperature of the recovery chamber is maintained in a desired temperature range by controlling the rate of circulation of the reagent solution through the recovery chamber heat assembly and the rate of energy supply to the recovery heat assembly.  
         [0012]     The vacuum pump discharges pressurized concentrated water vapor to a concentrated vapor line which carries the pressurized concentrated water vapor to an extraction energy exchanger which condenses water from the pressurized concentrated water vapor.  
         [0013]     As water is vaporized from the recovery chamber liquid surface the concentration of the reagent in the recovery chamber is increased. Re-circulated reagent is returned by a reagent re-circulation pump through a reagent re-circulation line to the reactive chamber to maintain hydraulic balance between the reactive chamber and the recovery chamber and to maintain the concentration of reagent in the reactive chamber.  
         [0014]     The preferred embodiment of the water extraction apparatus provides for gravity flow of reagent solution from the reactive chamber to the recovery chamber, with the rate of flow of the reactive chamber reagent solution being determined by the rate of water extraction from the recovery chamber by the vacuum pump and the rate of re-circulation of the re-circulated reagent from the recovery chamber to the reactive chamber.  
         [0015]     The energy required for the extraction energy exchanger, the recovery vacuum pump, the recovery chamber temperature control pump, and the reagent re-circulation pump will be substantially less than the energy required by a heat exchanger for condensing water directly from the ambient atmosphere. The use of waste heat from an energy source to heat the reagent solution in the recovery chamber enhances this benefit.  
         [0016]     Another preferred embodiment of the water extraction apparatus of the present invention can be used to purify raw water. For this embodiment, raw water preferably filtered to remove suspended solids, is fed to the reactive chamber and mixed with the reagent. Sulfuric acid is preferred by the inventor for raw water embodiments, because of the advantages of sulfuric acid which are identified above and because of the inherent characteristics of sulfuric acid to destroy pathogenic organisms and to break down organic compounds in raw water. Because the reaction of the reagent with organic and inorganic compounds in the raw water, makeup reagent is added to the reactive chamber based upon ph measurements from a ph sensor. To maintain desired liquid levels in the reactive chamber and the recovery chamber with the addition of makeup reagent, reagent solution may be extracted periodically from the reactive chamber as spent reagent. Otherwise, embodiments of the water extraction apparatus for the extraction of potable water from raw water have the same components as that used for the extraction of water from ambient air.  
         [0017]     The reaction of the raw water with the reagent before the water is extracted from the reagent solution by vacuum in the recovery chamber results in the elimination of pathogens from the water. Hence the probability that pathogens will survive the reactive chamber and the recovery chamber, and penetrate the vaporization process in the recovery chamber, is very low. It is unlikely that chlorination or other disinfectant processes would be required for the extracted water before culinary use, even if the raw water is raw or partially treated sewage water. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a block diagram flow chart of a preferred embodiment of the water extraction apparatus of the present invention for extracting water from air containing water vapor.  
         [0019]      FIG. 2  is a schematic vertical cross-section of a preferred embodiment of the water extraction apparatus of the present invention for extracting water from air containing water vapor.  
         [0020]      FIG. 3  is a block diagram flow chart of a preferred embodiment of the water extraction apparatus of the present invention for purifying raw water. 
     
    
     DETAILED DESCRIPTION  
       [0021]     Referring first to  FIG. 1 , a block diagram flow chart of a preferred embodiment of the water extraction apparatus  1  of the present invention is shown. Pressurized feed air  11  from any source of air, including ambient atmosphere, containing water vapor is supplied to a reactive chamber  21  containing a reagent with water absorption properties. The inventor prefers sulfuric acid as the reagent. The water vapor is absorbed from the pressurized feed air and spent air  23  with most of the water removed is discharged to atmosphere. Reagent solution  29  is transmitted to a recovery chamber  39  where concentrated water vapor is extracted from the reagent solution which is heated by recovery heat  95  supplied from an energy source  97 . The concentrated water vapor is extracted in a concentrated vapor zone created by a vacuum pump  43 , which also pressurizes concentrated water vapor for an extraction energy exchanger  73  which discharges extracted water  81 . Heat of cooling and vaporization  93  is extracted from the extraction energy exchanger by a heat exchange device  79 . Concentrated reagent  83  is re-circulated from the recovery chamber to the reactive chamber.  
         [0022]     As indicated above, the inventor prefers sulfuric acid as the reagent for the reactive chamber. However, other acids and other reagents with water absorption characteristics which also have a higher vaporization temperature than water for a given pressure can be used. Sulfuric acid is preferred because of its high water absorption capability, high vaporization temperature, high heat of vaporization, and relatively low cost.  
         [0023]     Referring now to  FIG. 2 , a schematic vertical cross-section of a preferred embodiment of the water extraction apparatus  1  of the present invention is shown.  FIG. 2  illustrates the use of the water extraction apparatus for the extraction of water from ambient atmosphere  3 . However, the embodiment of the water extraction apparatus shown can be utilized with any source of air containing water vapor, such as spent steam from a steam turbine engine. While the water extraction apparatus will be more efficient with feed air having a high water content, it will extract water from air having a low water content, such as desert air having an average relative humidity of five percent.  
         [0024]     Feed air  5  from the ambient atmosphere  3  is pulled into an air intake  7  and is pressurized by intake blowers  9 . Pressurized feed air  11  is transmitted by a feed pipe  13  from the intake blowers to a diffuser assembly  15  which diffuses, distributes and mixes diffused feed air  17  with reagent  19  in a reactive chamber  21 . If the reagent is sulfuric acid, the acid molecules in the reactive chamber react with the water molecules in the diffused feed air. The water is captured as reagent solution  29 , which will be an acid solution if the reagent is sulfuric acid, in the reactive chamber. Spent air  23 , which is the diffused feed air with most of the water content of the feed air removed, is released from a reactive chamber vent  25 . The spent air will generally have a relative humidity of less than one percent. For the embodiment shown, the reactive chamber has an upper gas segment  27  which is preferably maintained at or above ambient atmospheric pressure. The amount of water lost in the spent air can be reduced by increasing the pressure in the upper gas segment of the reactive chamber. The reactive chamber vent can be controlled to maintain a desired pressure in the upper gas segment.  
         [0025]     The diffuser assembly is preferably located near the bottom of the reactive chamber. As an alternative to a diffuser assembly, mechanical mixing or other diffusion means for diffusing, mixing and distributing the pressurized feed air in the reactive chamber will be known to persons skilled in the art. Likewise, other air feed means will be known to persons skilled in the art.  
         [0026]     Reagent solution is transmitted to the reagent recovery chamber  39  by an upper reagent solution line  31  or a lower reagent solution line  33 , each of which connect to a reactive chamber feed line  36 . An upper reagent valve  35  and a lower reagent valve  37  are used to select the upper portion of the reactive tank or the lower portion of the reactive tank for passing reagent solution to the reagent recovery chamber. Either the upper reagent solution line or the lower reagent solution line can be used for continuous transfer to the reagent recovery chamber and the lower reagent solution line can be used for batch transfer of reagent solution to the reagent recovery chamber.  
         [0027]     A recovery vacuum pump  43  which is connected to a concentrated vapor zone  41  by a vacuum pipe  45  imposes a vacuum on the recovery chamber liquid surface  51 , which results in an accelerated vaporization rate for the water in the reagent solution. Other vacuum means for imposing a vacuum on the recovery chamber liquid surface will be known to persons skilled in the art. The inventor has found that a temperature ranging between 180° Fahrenheit and 200° Fahrenheit for the recovery chamber reagent solution  53  is preferred for optimizing the vaporization of water from the reagent solution in the reagent recovery chamber, if sulfuric acid is used for the reagent. However, other temperatures can be used effectively, even for sulfuric acid, depending on the vacuum imposed in the concentrated vapor zone.  
         [0028]     A recovery chamber temperature sensor  67  is used to activate a recovery chamber heat assembly  69  which, for the embodiment shown, includes a recovery chamber temperature control pump  63  which pumps reagent solution  53  from the recovery chamber by a recovery heat line  57  through a recovery heat exchanger  61 . The temperature sensor can also be used to control the rate of supply of recovery heat  95  by a heat supply line  65  from an energy source  97 . The temperature of the recovery chamber is maintained in a desired temperature range by controlling the rate of circulation of the reagent solution through the recovery chamber heat assembly and the rate of energy supply to the recovery heat assembly. Other recovery chamber heat assemblies  69  and other recovery chamber heat supply means will be known to persons skilled in the art. Waste heat from a steam turbine or other process can be used as an energy source for the recovery chamber heat assembly. A solar collector can also be used to provide a heat source for the recovery chamber heat assembly.  
         [0029]     The vacuum imposed by the recovery vacuum pump  43  accelerates the formation of concentrated water vapor  47  in the recovery vapor segment  41  of the recovery chamber. The concentration of water vapor in the recovery vapor segment is substantially higher than the concentration of water vapor in the ambient atmosphere.  
         [0030]     The vacuum pump discharges pressurized concentrated water vapor  55  to a concentrated vapor line  71  which carries the pressurized concentrated water vapor to an extraction energy exchanger  73  which condenses water from the pressurized concentrated water vapor. Other extracted water condensation means for condensing the concentrated water vapor will be known to persons skilled in the art. The extracted water  81  can be conveyed by a discharge pipe  77  to a storage tank or directly to a water use application. A number of heat extraction devices  79  for extracting cooling and condensation heat  93  from the pressurized concentrated water vapor in the extraction energy exchanger will be known to persons skilled in the art. No doubt additional advances in technology will also provide additional heat extraction means for condensing the water from the pressurized concentrated water vapor. Discharge air  91  with most of the water vapor removed is discharged from a discharge port  75  in the extraction energy exchanger, thereby dissipating residual pressure.  
         [0031]     As water is vaporized from the recovery chamber liquid surface  51  the concentration of the reagent in the recovery chamber is increased. Re-circulated reagent  83  is returned by a reagent re-circulation pump  85  through a reagent re-circulation line  87  to the reactive chamber  21  to maintain hydraulic balance between the reactive chamber and the recovery chamber and to maintain the concentration of reagent in the reactive chamber. Liquid level sensors in the reactive chamber and the recovery chamber can be used to control the reagent re-circulation pump. Other chamber liquid level control means will be known to persons skilled in the art.  
         [0032]     The preferred embodiment of the water extraction apparatus shown in  FIG. 2  provides for gravity flow of reagent solution from the reactive chamber to the recovery chamber, with the rate of flow of the reactive chamber reagent solution  29  being determined by the rate of water extraction from the recovery chamber by the vacuum pump and the rate of re-circulation of the re-circulated reagent  87  from the recovery chamber to the reactive chamber. Other hydraulic designs, hydraulic interconnection means, and hydraulic control means will be known by persons skilled in the art for the reactive chamber, the recovery chamber, the reagent solution lines between the reactive chamber and the recovery chamber, and for the reagent re-circulation means.  
         [0033]     The energy required for the extraction energy exchanger  73 , the recovery vacuum pump  43 , the recovery chamber temperature control pump  63 , and the reagent re-circulation pump  85  will be substantially less than the energy required by a heat exchanger for condensing water directly from the ambient atmosphere. The use of waste heat from an energy source  71  to heat the reagent solution in the recovery chamber enhances this benefit.  
         [0034]     Referring now to  FIG. 3 , a block diagram flow chart of a preferred embodiment of the water extraction apparatus  1  of the present invention that can be used to purify raw water is shown. This embodiment is very similar to the embodiment shown in  FIG. 1 . For this embodiment, raw water  99 , preferably filtered to remove suspended solids, is fed to the reactive chamber  21  and mixed with the reagent  19 . Raw water mixing means for mixing the raw water with the reagent will be known to persons skilled in the art. Diffusers such as that used for feed air for the embodiment shown in  FIG. 1  and  FIG. 2  could be used for raw water mixing but will generally not be preferred for raw water embodiments. Sulfuric acid is preferred by the inventor for raw water embodiments, because of the advantages of sulfuric acid which are identified above and because of the inherent characteristics of sulfuric acid to destroy pathogenic organisms and to break down organic compounds in raw water. Because the reaction of the reagent with organic and inorganic compounds in the raw water results in a gradual decrease in the reactive chamber of the ph of the reagent solution, if an acid is used, or in a gradual effective decrease in reagent concentration for all reagents, and the concentrated reagent in the recovery chamber, makeup reagent  101  is added to the reactive chamber based upon ph measurements from a ph sensor  105 . To maintain desired liquid levels in the reactive chamber and the recovery chamber with the addition of makeup reagent, reagent solution may be extracted periodically from the reactive chamber as spent reagent  103 . Otherwise, the water extraction apparatus shown in  FIG. 3  has the same components as that used for the extraction of water from ambient air as shown in  FIG. 1  and  FIG. 2 . Of course, sizing of components is dependent on the quantity of raw water to be processed. The extracted water  81  for this embodiment will be potable water, having a quality that is close to the quality of distilled water.  
         [0035]     The reaction of the raw water with the reagent before the water is extracted from the reagent solution by vacuum in the recovery chamber results in the elimination of pathogens from the water. Hence the probability that pathogens will survive the reaction process and the long term exposure to the reagent in the reactive chamber and the recovery chamber, and penetrate the vaporization process in the recovery chamber, is very low. It is unlikely that chlorination or other disinfectant processes would be required for the extracted water before culinary use, even if the raw water is raw or partially treated sewage water. Again, the removal of solids from the raw water before being fed to the reactive chamber is preferable as the buildup of solids in the reactive chamber or the recovery chamber is undesirable. While embodiments could provide for the handling of solids which might settle out in the reactive chamber or the recovery chamber, those embodiments are not preferable.  
         [0036]     Other embodiments and other variations of the embodiments described above will be obvious to a person skilled in the art. Therefore, the foregoing is intended to be merely illustrative of the invention and the invention is limited only by the following claims and the doctrine of equivalents.