WO2002030540A1

WO2002030540A1 - Household water distiller and hot water supply

Info

Publication number: WO2002030540A1
Application number: PCT/US2001/031181
Authority: WO
Inventors: Charles R. Cutler
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-10-11
Filing date: 2001-10-04
Publication date: 2002-04-18
Anticipated expiration: 2003-04-11

Abstract

An apparatus and method for distilling water for a home while supplying hot water. A hot water tank (1) is placed in a mode of continuous circulation through a condenser (3) by use of a small circulating pump (11). The condenser is part of a distiller unit (2) and condenser combination that operates whenever the thermostat (23) of the hot water tank indicates a need to raise the temperature of the hot water in the tank. The distiller unit generates steam from feedwater, a heating element (18) for the distiller unit is connected to draw electric power from the hot tank power source and responsive to the htermostat of the hot water tank power source and responsive to the thermostat of the hot water tank. The distiller unit, condenser, and feed water system (13) are designed to provide quality distilled water in a reliable, long running system with straightforward control elements.

Description

HOUSEHOLD WATER DISTILLER AND HOT WATER SUPPLY

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TECHNICAL FIELD

This invention is an improved apparatus and method used for distilling water. In particular the invention is for an apparatus that works in conjunction with home hot water systems to generate quality distilled water for the home while recovering the heat from that distillation to supply hot water for the home or small business.

BACKGROUND ART

There has long been recognition of the need for relatively small quantities of purified and distilled water for household use. The continuing needs for steam irons, contact lens cleaning, etc., continue in importance, but are small. Recently there has been a growing interest in better quality drinking water and in many areas of the country that is becoming more difficult. Thus there is anticipated to be a growing interest in home distilled water supplies. Conventional home distillers are energy inefficient however, and may heat up the area around them or require dumping large amounts of hot water to the drain system. They are also expensive to operate, delivering distilled water for roughly 33 U.S. cents per gallon. Thus there has already been recognition that coupling a water distillation unit with the hot water system could overcome these difficulties.

The notion of simultaneously supplying distilled water and supplying hot water to a household is not a new one. US Patent 2,217,266 (Cookson) in 1939 described a combined system in which an electrically heated water distilling apparatus was mounted inside a tank of water in which the surrounding water condensed the steam of the boiler and was then used for heating purposes. Sims (3,718,544) described another combined system that makes use of a tank that is not insulated at the top so that some water vapor condenses there and is collected as distilled water. Erickson (4,549,936) described a combined hot water and distilled water system that creates a partial vacuum to enable distillation at a lower temperature. Palmer (4,906,337 and 5,304,286) described a combined system in which the hot water heater was modified to insert the distilled water condenser inside the hot water tank. These devices and others similar to them have not enjoyed great commercial success to date. One problem has been that they have been fairly complex in operation compared to conventional hot water heaters and some required removal and replacement or modification of the existing hot water heater. A hot water heater, being a simple apparatus, has evolved into a very reliable household device that operates for years without any significant maintenance. Consumers are wary of a new device which appears more complex and thus may reduce the reliability of their hot water supply.

Another complexity of these systems is the attempt to predict and control the differing potential demands of hot water and distilled water in typical households and put in extra control systems to handle differing loads. This complexity can also reduce the reliability of the hot water utility.

Another problem has been in the taste of the resultant distilled water, which is strongly linked to carry-over of water droplets from the violent action of a boiler and to proper removal of trace volatile organic compounds. Most of the prior art devices do not address these issues.

Another problem is dealing with the formation of hard salts that develop in the boiler, which can foul the inlet water line and coat out on any level measurement system and thus require frequent shutdowns for clean-up. In devices in which the distillation and hot water supply are integrally combined this can mean frequent loss of the hot water utility.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a reliable system for generating good quality distilled water and providing all the hot water for a household or small business for extended periods of operation. A further object of the present invention is to provide a system that works in cooperation with a conventional hot water heater without requiring modification or replacement of the hot water heater.

A further object of the present invention is to provide a system that ensures the typical reliability of a hot water system by falling back to conventional hot water heater operation during down time of the distilled water system.

A further object of the present invention is to provide a system that is not shut down frequently by scale formation.

The invention is a water distillation apparatus for coupling to an electrically heated hot water tank. It includes at least a distiller unit for generating steam from feed water; a heating element for the distiller unit connected to draw electric power from the hot water tank power source and responsive to the thermostat of the hot water tank; a condenser connected to the distiller unit for condensing the steam; and a pump connected to continuously draw hot water from the hot water tank exit line and circulate hot water through the condenser for return to the hot water tank.

The invention also includes a method for generating distilled water in conjunction with a hot water tank including at least pumping, in a continuous manner, hot water from the hot water tank exit line through a condenser and back to the hot water tank inlet line; feeding a distiller unit with feed water, the feeding responsive to a level measurement in the distiller unit; heating the feed water with electric heating element to produce steam that flows to a condenser, the heating element connected to and responsive to the thermostat reading of the hot water tank; and condensing the steam in the condenser, via heat exchange with the hot water being pumped from the hot water tank exit line through the condenser.

The concept of the invention is to use a circulating pump to put a conventional home hot water heater on continuous circulation through a heat exchanger. The heat exchanger is a condenser for a water distiller. The condenser is sized to condense all of the steam output from a boiler that receives power from the electric power source of the hot water heater in response to the thermostat of the hot water tank. The steam is condensed at the temperature of the hot water and flows by gravity to a distilled water receiver for use in the household. The distilled water boiler supplies all the heat necessary for the hot water needs of the household. The hot water needs of a typical U.S. home would result in 4-5 gallons of distilled water per day using this concept. This would provide all the distilled water needs of a typical household. Any excess distilled water would simply overflow to the drain. This concept results in design simplicity in that the only controllers needed are the thermostats of the existing hot water heater and a simple float level control to regulate feed water to the boiler.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic block diagram showing an integrated water distiller system and hot water heater according to a first embodiment of the system.

FIG. 2 is a more detailed schematic diagram of the distilled water system, in connection with more than one hot water heater.

FIG. 3 is a perspective view of a two-chamber distiller module used in a preferred embodiment of the invention.

FIG. 4 is a view of the arrangement of the float in a preferred embodiment of the invention

MODES FOR CARRYING OUT THE INVENTION

The invention is a distilled water unit and heat exchanger condenser connected in heat transfer relation to a conventional hot water heater by means of a continuous circulating pump.

Referring first to figure 1 , the construction and operation of the system according to the invention will be described in a general sense. A pump 11 is connected on the suction side to a block valve 4A on an exit hot water line 9 of a hot water tank 1. The pump discharges through a condenser 3. The exit side of the condenser is connected to another block valve 4B, which is connected back to an inlet line 10 of the hot water tank. This structure completes a continuous circulating loop of hot water from the hot water tank exit line 9 through the condenser 3 and back to the hot water tank inlet line 10.

Figure 2 illustrates, in detail, the construction of a preferred embodiment of the invention, in which the distillation sub-system operates in connection with multiple hot water heaters 1 , useful in applications such as apartment complexes, office buildings, or larger homes. While use with multiple hot water heaters 1 is illustrated in Figure 2, it is too be understood that the system works with one hot water heater if desired.

Figure 2 shows a feed water source 13 connected to a filter 14, which is connected to a water softener unit 15. The water softener unit 15 is connected via line 6 to a control valve 16 set above the liquid level in a distiller unit 2. The control valve 16 is mechanically connected for control purposes to a float 17 in the distiller unit 2. The distiller unit also contains an electrical heating element 18, connected electrically to draw power from the hot water tank (or tanks) power source when the built in thermostat 23 of the hot water tank indicates a need to raise the hot water tank temperature. The power 12 from the hot water tanks 1 is also electrically connected to and activates a solenoid valve 25 at the base of the distiller that periodically purges water from the distiller unit. The solenoid valve is connected to a cooling unit 19 to cool the purged hot water before discharge to the drain. Turning now to the distiller unit 2 a preferred embodiment is shown in figure 3. The distiller unit is divided into a boiling chamber and a float chamber. A weir 22 separates the two chambers but allows both the liquid phase and the vapor phase to freely communicate via openings in the top and bottom of the weir. The boiling chamber contains the electric heating element 18. The float chamber contains the water inlet valve 16, connected to feed water via line 6. The valve 16 is mechanically connected to the float 17.

Referring back to figure 2 a steam outlet 21 is connected to line 7, which is connected to condenser 3 and to an internal condensing coil in the condenser. The condensing coil exits the condenser and is connected to distilled water line 5 which flows to distilled water storage (not shown). Directly on the distilled water line 5 is a vapor disengager 24, which allows any volatile impurities to separate from the distilled water and be vented.

In operation feed water for the distiller unit 2 passes through a filter 14 to remove particulate material and prolong system operation. The filtered water then passes through a water softener unit 15 to remove hard mineral salts such as calcium and magnesium salts that can lead to fouling and shutdown of the distiller unit.

Filtered and softened feed water from the water softener 15 enters the distiller unit 2 through a valve 16 positioned to be permanently above the level of water in the distiller unit. This aspect of the preferred embodiment was found experimentally to be critical to avoiding the formation of hard salt scale in the inlet valve. Scale formation is a strong function of water temperature and the positioning of this valve well above the hot water allows the cool inlet water to keep the valve 16 cool enough for extended operation without scale formation.

The inlet valve 16 is operated by a float 17 mechanism that opens the valve when the water level of distiller unit 2 falls below a pre-determined value. The heating element 18 remains well below the level of water in the distiller at all times and is the only heat source for the system during normal operation, since the distiller unit provides all the necessary heat for both distilled water and hot water. In operation, purge lines, located at the bottom of each chamber of the distiller are used to remove impurities and fouling agents from the bottom of the boiler. The purge lines pass through a solenoid operated valve 25 driven by a timer, which can be preset at any desired frequency of operation. . The power to the solenoid valves and the timer are turned on when the thermostat on the hot waster tank activates the heating element of the boiler. This arrangement prevents the purging of water from the distiller when the distiller is not in operation.

As noted above relative to figure 3, distiller unit 2 has two separate chambers and a designed vapor space over the water level. Experimentation with a one and two chamber system showed significant advantages to separating the distiller into a float chamber and a boiling chamber, separated by a weir 22 that allows communication of both water and steam between the two chambers. The two chamber system confines the most violent boiling action to the boiling side, resulting in less dynamic play on the float mechanism 17, significantly extending the life of the float. Floats in most typical boiling environments suffer high torque on the float-valve extension, leading to eventual mechanical failure.

The use of two chambers in the distiller unit 2 also effectively stages the distillation to give better separation of water from the impurities, leading to higher quality and improved taste of the water. The steam generated in the boiling chamber passes through an outlet at the end of the chamber that turns the steam 90 degrees as it enters the second (float) chamber. In the float chamber the steam is forced to turn another 90 degrees and flow the length of the chamber to the exit port. This 180 turn knocks out entrained droplets, significantly increasing resulting distilled water quality. Taste tests by the inventor confirmed that this combination of a significant vapor space and tortuous path for the steam dramatically improved the taste of the distilled water.

As noted above relative to figure 4, it has been found through experimentation that the design of float 17 influences the stability of it's dynamic behavior. According to the preferred embodiment of the invention float 17 is constructed as an elongated rectangular metal box with square ends. The float 17 is positioned such that a diagonal drawn between the opposite corners of the square end of the float is parallel with the water. This positioning causes the float 17 to ride stable in the water and does not transmit torque to the coupling of the valve resulting from the turbulent action of boiling. Further the square end on the float 17 represents the maximum volume for a rectangular box, which permits the use of a thicker and heavier metal for the float. The thicker metal increases reliability of the float.

Steam exit the distiller 2 enters the condenser 3 where it is condensed completely to distilled water in a tubular arrangement in which the hot water is on the outside of the tube. Although shown as a simple coiled tube in a chamber it should be obvious that a number of different designs will accomplish the same function. For one example a conventional shell and tube heat exchanger could be employed.

The distilled water exit the condenser in line 5 was condensed at the temperature of the hot water in the hot water system and is thus at an ideal temperature for removal of any trace volatile organics that can lead to odor or taste problems in distilled water intended for drinking. The distilled water (condensed steam) exit the condenser enters a vapor disengagement device 24 where the volatiles are disengaged and vented overhead 20. The distilled water 5 then flows by gravity to a distilled water receptor.

INDUSTRIAL APPLICABILITY

According to the present invention extensive design and testing has developed a distilled water system operating in conjunction with a conventional hot water system that is simple in concept and has been shown to operate for the equivalent of 3-4 years operation without maintenance shutdowns.

The only mechanical modification needed in a household with a conventional hot water heater is the minor external plumbing needed to connect the circulating pump to a hot water tank exit line and to return the hot water to a hot water inlet line. Electrically the power controlled by the thermostat of the hot water heater is connected by a switching arrangement to the heating element of the distiller unit 2 instead of to the heating element of the hot water heater. A plumber and electrician can easily make these two modifications. The beauty of this arrangement is that if a shutdown of the distiller - condenser system is needed for maintenance the electric power is switched back to the hot water tank and two block valves 4A and 4B are closed to isolate the hot water tank form the circulating pump 11 and circulating loop 8. The hot water tank then reverts to normal operation.

The invention described here has several benefits over other systems. The concept of creating a hot water system continuously pumped in a circulating manner through the distiller condenser provides several improvements that lead to improved operating utility, improved system capacitance, and improved water quality. This approach of a circulating loop of hot water makes it possible to connect such a system to multiple hot water heaters in cases of a larger household or apartment or a small business. The circulating pump runs continuously to normalize the temperature in the hot water tank. The resultant mixing permits the thermostat to see any change in temperature sooner, since there is stratification of the water in the tank under normal once through operation. The continuous circulation thus improves the temperature control and effectively raises the capacitance of the hot water system.

The combination of a water softener, the design of the water inlet to the boiler, and the purge system results in a system that does not foul with typical water hardness. 3-4 years of equivalent operation have been demonstrated with no cleaning of the boiling chamber required.

The combination of a staged two chamber distiller with pre-softened water and volatile gas removal results in a system that consistently yields good tasting water.

Although an embodiment of the invention has been described with some particularity, a number of modifications in the preferred embodiment are possible in light of the above teachings. Therefore, it should be understood that, within the scope of the appending claims, the invention may be practiced other than as specifically described.

Claims

CLAIMSWhat is claimed is:

1. A water distillation apparatus for coupling to at least one electrically heated hot water tank comprising:

a distiller unit comprising a tank having an inlet for feed water, an outlet for steam and a heating element; said heating element connected to draw electric power from electric power source of said hot water tank, and responsive to thermostat of said hot water tank;

a condenser connected to receive steam from said distiller unit for condensing said steam; and

a pump connected to draw hot water from exit line of said hot water tank and circulate hot water through said condenser for return to inlet line of said hot water tank.

2. The apparatus in claim 1 in which said distiller unit comprises:

a two chamber unit consisting of a boiler chamber and a float chamber separated by a weir that allows water and steam to transfer between the chambers; and

said boiler chamber containing said heating element to raise the water temperature to the boiling point and said float chamber containing a feed water inlet valve connected to and controlled by a level float.

3. The apparatus of claim 2 in which said level float is an elongated rectangular box that is square on the ends and the float is arranged so that a diagonal drawn across the square at the end of the rectangular box is parallel to the water level.

4. The apparatus of claim 2 in which said feed water inlet valve is positioned above the water level in said float chamber.

5. A method for generating distilled water in conjunction with at least one hot water tank comprising:

pumping, in a continuous manner, hot water from a hot water exit line of said hot water tank through a condenser and back to a feed water inlet line of said hot water tank;

feeding a distiller unit with feed water, said feeding responsive to a level measurement in said distiller unit;

heating said feed water with electric heating element to produce steam that flows to the condenser; and

condensing said steam into distilled water in said condenser, via heat exchange with said hot water being pumped from said hot water tank exit line through said condenser.

6. The method of claim 5 in which the electric heating element receives power from the electric power supplied to said hot water tank in response to the thermostat reading of the hot water tank.

7. The method of claim 5 further comprising venting said distilled water exit the condenser to remove volatile organics.

8. A system for generating hot water and distilled water comprising:

A distiller unit comprising a vessel having an inlet for feed water, an outlet for steam, and a heating element;

a condenser connected to receive steam from said distiller unit for condensing said steam into distilled water; a hot water system comprising a tank with inlet and outlet lines, an electric power source, and a thermostat;

said heating element connected to draw electric power from said electric power source when said thermostat indicates the temperature in said hot water system falls below a pre-determined value; and

a pump connected to continuously circulate hot water from said exit line of said hot water tank through said condenser and to said inlet line of said water tank.