Abstract:
A compact distilled water system for home, marine, and laboratory use which includes a closed circuit that provides high pressure water for dispensing water to remote locations and that also creates, in conjunction with an eductor, a partial vacuum in the evaporator tank to permit boiling and steam generation therein below atmospheric pressure.

Description:
This invention relates to a new and improved water distillation unit, which includes a closed distilled water circulation system that functions to produce water under pressure to dispensing lines, while also in combination with an eductor creates a partial vacuum in the evaporator tank to permit water to be boiled and steam generated below atmospheric pressure. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention is particularly designed for use as a compact, automatic purified water distillation unit of the type especially adapted for home use to produce 4-6 gallons, more or less, drinking water per day for an average sized family. The unit is also especially adapted for relatively small office use to take the place of bottled water stands as may be found in many offices as well as residential homes. 
     The unit embodying the present invention may be designed for home installation under a conventional kitchen sink, along with required utility connections including electrical, feed water supply, and waste water drainage. The unit may be plumbed to supply the distilled water to a dedicated faucet installed faucet at the sink, and also to supply distilled water to the inlet of an ice-making machine such as located in the freezer department of a conventional refrigerator, or the like. 
     In addition to home installations, a unit embodying the invention is extremely well suited for desalination of sea water in marine applications and/or purification of any water in industrial as well as other applications outside the home. Depending on distilled water needs in terms of volume, a unit embodying this invention may be scaled up or down to produce anywhere from a few gallons a day to thousands of gallons per hour. 
     Numerous functional advantages are obtainable using the present distillation system including: 
     1) The closed circuit component above-mentioned, creates a partial vacuum in the evaporator so that feed-water supplied to said evaporator can be heated to boiling point and converted to steam at below atmospheric boiling point (which at sea level is 212° F.). The boiling of water at lower temperatures prevents scale buildup on the heating elements and heat transfer surfaces installed in the evaporator tank. The building up of scale is perhaps the singularly most inconvenient and annoying part of standard systems where boiling is at atmospheric pressure and at higher temperatures. Scale buildup reduces the efficiency of the heat transfer from the heating elements to the surrounding water and must be cleaned out on a regular basis with acid to prevent massive scale buildup which will stop the distillation process and cause heater failure. 
     2) A second benefit of operating at lower temperatures is that it allows the use of plastics, rather than more expensive and difficult to work with metals, in various components where feasible. 
     3) The present unit is both fully automatic and is water cooled (air cooling is optional). Most home size distillers are batch operations, and are not automated. The consumer must monitor the quantity of water in storage, drain the evaporator, refill the evaporator and start the distiller when more water is required. Another negative aspect of more conventional home distillers is that the steam condenser coils are usually air-cooled instead of water-cooled. Thus, all of the heat from the process is air blown into the room to raise the overall room temperature which can be obviously undesirable, especially in hot climatic conditions. 
     4) An “under the sink” unit embodying the present invention can be produced and marketed at cost competitive with or lower than the cost to a home owner of using bottled water, with its multiple attendant disadvantages of requiring the heavy lifting of full bottles into inverted positions in the water dispensing stand as well as putting up with the clutter and wasted floor space used by the dispenser and full and empty bottles. 
     Other objects and advantages of the invention will become apparent upon reading the following specification and referring to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a flow diagram and schematic view of a first embodiment of a distilled water unit or system with many of the components labeled with descriptive words and symbols to readily enable a person skilled in the art to readily comprehend the system viewed in its entirety. 
     FIG. 2 is similar to FIG. 1 of a second embodiment except that a separate heater tank and other features have been eliminated from the system. 
     FIG. 3 is a third embodiment similar to FIG. 2 showing a different heating source and adaptable for marine and other applications adjacent an internal combustion engine or the like. 
    
    
     DESCRIPTION OF THE INVENTION 
     Referring more specifically to FIG. 1, particular attention is directed to the major components comprising the distilled water closed circuit which operates under pressure in a manner to be described. Distilled water from the pure water storage tank  1  is withdrawn from its bottom outlet  2  by a circulation pump  3  into a first conduit  4 . The distilled water under pressure flowing through conduit  4  is directed into the inlet or high pressure side  5  of an eductor  6 . Water pumped through conduit  4  and inlet  5  flows through the eductor and is discharged into the upper inlet side  7  of storage tank  1 . Various automatic and conventional water level switches (as designated) are provided in storage tank  1  to maintain desired minimum and maximum levels. 
     Branch line  4   a  of conduit  4  is operable to pump a portion of the distilled water discharged from storage tank through the circulation pump  3  to one or more destinations, including heating tank  8  via branch line  4   a  and feeder line  9 . Line  9  includes solenoid valve  9   a  that regulates the amount of water pumped into the heater tank utilizing standard control systems as designated in FIG.  1 . 
     A portion of the distilled water pumped flowing through branch line  4   a  may also be diverted through check valve  11  to remotely located distilled water dispensing sources including, for example, a faucet as may be installed on a sink (not shown) and/or to the inlet port of a conventional ice-making machine and chilled water dispenser as may be housed within the standard refrigerator (not shown). 
     In FIG. 1, distilled water pumped into heater tank  8  is heated by conventional electric immersion heating elements  24  to a predetermined temperature below the atmospheric boiling point and preferably in the range of 120° F. to 210° F. The heating tank is vented to atmosphere. However, because the water is not brought to the atmospheric boiling point, there is no live steam generated in the heating tank to vent into the room. Having the heating element immersed in distilled water and not boiling this water maximizes the heater life as well as providing a source of hot distilled water. 
     The heating tank  8  is mounted within evaporator tank  12  whereby the common vertical tank wall  13  establishes a surface area for transferring heat from the heated distilled water in tank  8  to the surrounding feed-water which is automatically supplied as needed to the evaporator tank  12 . Specifically, evaporator tank  12  is connected to feed-water supply  14  via conduit  16 , control valve  18 , condenser unit  17 , control valve  16   a , and conduit  21 . 
     Because the interior of evaporator tank  12  is maintained at a vacuum (by means to be described), feed-water in tank  12 , to which heat is transferred from surface  13 , will boil within the range of 110° F. to 208° F. whereby pure steam thus generated will outflow through conduit  22 , through condenser coil  17  whereby the steam is condensed into pure distilled water by the time it flows into conduit  23  connected to the suction side  6   a  of eductor  6 . As can be seen from the FIG. 1 flow diagram, the condenser coil  17 , through which the steam from evaporator tank flows, is water-cooled by the feed-water running through control valve  18 , the condenser water jacket  17   a , flow restricter  15 , and discharged to drain via conduit  20 . 
     Heretofore I have described the overall basic elements of the entire water distillation system. Particular attention is now directed to a novel and key subsystem in the form of a closed circuit comprising the storage tank  1 , pump  3  and eductor  6  and their cooperative and functional relationship to each other and to the overall system operation. More specifically, the storage tank  1  serves not only to store a reservoir of distilled water for immediate dispensing, but said tank in cooperation with pump  3  and its related plumbing supplies the feed water to heating tank  8  that in turn becomes the heat source for evaporation tank  12 . Pump  3 , in cooperation with eductor  6  and storage tank  1  define a closed circuit, whereby water pumped under high pressure through eductor  6  creates the necessary partial vacuum in lines  17 ,  23 ,  22 , and the evaporator tank  12 —thus making it possible to boil the raw feed water at well below atmospheric pressure from heat supplied by the heating tank as above described. Eductor  6 , by its very nature, has a high pressure side from the pump, a high velocity constricted mid-section, and a low pressure side to which line  23  is shown connected at  6 ( a ) in the drawings. 
     It will be apparent that the low pressure water flowing into storage tank  1  will also suck into its stream the additional distilled water from line  23  as produced by steam generated in the evaporator tank and condensed along the way in condenser coils  17 —the latter being cooled by raw feed water from Source  16  flowing into water jacket  17   a.    
     From the foregoing description, it will be seen that the circulation pump  3  performs multiple functions. Not only does it supply all, or at least part of, the distilled water under pressure to the heating tank and remote distilled water distribution sources (e.g., faucet, water chiller/ice-maker), but pump  3  also supplies water to the inlet side  5  of the eductor  6  at a high pressure and flow rate, providing sufficient motive to create the necessary partial vacuum within the evaporator tank and condenser lines so that the distilled water storage tank is automatically refilled with distilled water from the newly generated condensed steam from the evaporator tank. 
     Referring now to FIG. 2 of the drawings, a second and simplified embodiment of the invention is depicted. This embodiment is in all major respects identical in construction and operation to the system shown and above described in reference to FIG. 1, except that the heating tank and evaporator tank are shown as an integral unit instead of two separate elements. The numbering of the same or corresponding parts common to both FIGS. 1 and 2 remain the same. 
     It is important to note that the same closed circuit component consisting basically of the distilled water storage tank  1 , pump  3 , and eductor  6  and related plumbing performs the identical multiple functions as heretofore described with reference to the first embodiment. 
     In particular, and comparing FIG. 1 to FIG. 2, it is noted that the separate heater tank  8  is absent from FIG. 2, and that a conventional heating element  24  is located in the evaporator tank  12  to heat the non-distilled feed water (from supply source  14  via line  21 ) to a pre-selected temperature range of 110° F.-208° F., for example. The feed water will boil and generate steam at these temperatures, while under partial vacuum as created in the tank by being connected to the low pressure side of the eductor  6  as heretofore explained. As will be obvious from a comparison between FIGS. 1 and 2, because there is no separate heating tank, there is not shown any distilled feed water line  9  as supplied from storage tank  1  appearing in FIG.  1 . 
     Although in FIG. 2 the heat source is depicted as a conventional electric resistance heater  24 , it should be understood that other heat source means may be substituted. For example, a shipboard installation may use the hot cooling water from any onboard internal combustion engine, as specifically shown in FIG.  3 . In FIG. 3, the heating element  24  is eliminated altogether, and in its place is substituted a heat exchange coil  25  which is in closed circuit hook-up with the fresh water cooling jacket of most any marine internal combustion engine (not shown). Specifically, conduit  26  shows inflow of hot engine cooling water which circulates through coil  25  and thence through return line  27  in closed circuit communication with the engine water cooling jacket. 
     The simplified embodiment of FIG. 2 has the advantage over the FIG. 1 unit of a somewhat lower manufacturing cost due to reduction in the number of parts, and the resulting simplified assembly process. The embodiment of FIG. 3 has the advantage over both FIG.  1  and FIG. 2 units in that it requires less than 1 percent of the energy used by the other units because waste heat provides the energy to boil the water. 
     From a consumers standpoint, the embodiment of FIG. 1 has the advantage over FIGS. 2 and 3 of permitting a direct line connection from distilled water in the separate heating tank directly to a dedicated hot water faucet mounted on the sink usually directly above or closely adjacent installation of the distillation unit. As shown in FIG. 2, the feed water contained in the combined heating and evaporator tank is not distilled, and thus no direct hot water faucet connection to said tank could produce the desired heated distilled water. 
     Although the invention has been described in some detail by way of illustration and example, it is understood that other changes and modifications may be made without departing from the spirit of the invention or the claims attended hereto.