GB2191567A - Electric steam generator with ground voltage-null control electrode - Google Patents

Abstract

A water heater for producing steam is adapted to be powered by an a.c. supply comprising two lines 6,7 balanced with respect to ground potential 13', the lines being connected to respective ones of a number of electrode plates 1,2 immersed in the water to be heated, and a third electrode 3 is disposed between the electrode plates substantially along a central equipotential line in use, the third electrode being connected to a conductive water container 5 of the heater. The water and container thereby have an electric potential of zero with respect to the ground so as to prevent electric shocks. <IMAGE>

Description

SPECIFICATION Electric steam generator with ground voltage-null control electrode This invention relates to a method and apparatus for directly converting electric energy into heat energy utilizing water as the heating medium itself to produce steam for general heating purposes; and to the use of a control electrode to bring the potential of the apparatus to ground voltage, hence eliminating the necessity of providing a grounding wire to prevent electric shock to the user of the device.

For decades, sincethe invention of the alternating current, it has been well known that when two plate electrodes, connected to an electric power source, are submerged in a given volume ofwater, electric current flow occurs. Since the resistance of the water is directly affected by the temperature, the current flow causes the resistance to decrease; such a resistance decrease subsequently increases the electric current flow, causing a corresponding 12R product to rapidly increase; hence power dissipated within the water itself increases, causing the temperature to rise to the boiling point. This method provides a very efficient system of converting electric energy directly into steam energy.

One primary disadvantage of this method is the presence of an electric potential (110 volts for a 220 volt distribution system) between the water (or its container) and the ground; since the water is directly connected electrically to the alternating current electrodes. This is one reason why this method has never been generally utilized by engineers to generate steam power.

When the heating element to generate heatforthe production of steam is composed of an electric wire, suchasforexample,nichromewire; andwhenthe heattransfer is accomplished by either: 1. heat conduction through the walls of a vessel to the water or 2. heat conduction through direct submersion of the heating element in the water to be vaporized into steam; auxiliary devices, such as a thermostatic powerswitch,would be required in orderto prevent overheating. Hence burning of the steam generator system, when the water is completely vaporized, is avoided.

The primary objective ofthis invention, isto provide an effective method and means for balancing the electric potential between the water and its containing vessel, and the ground. In other words, to make the system's potential equal to zero with respect to ground without the connection of the conventional grounding wire system designed to prevent electric shocks.

A secondary objective of this invention is to provide an effective method and means for converting electric energy directly into steam, by utilizing the water itself as the power-dissipating medium. This efficiently converts the water directly into steam energy.

According to the invention, there is provided a water heater adapted to be powered by an ac supply comprising two lines balanced with respect to ground potential, comprising at least two electrode plates arranged to be connected to the respective supply lines and to be directly immersed in water to be heated, and a third electrode disposed between the electrode plates substantially along a central equipotential line in use, the third electrode being arranged to be connected to a conductive water container of the heater.

The following drawings illustrate the basic scientific principles involved and its actual practical utilization in an example ofthe invention.

Figure 1 shows the electric circuit schematic diagram of an electric steam generator according to the invention; thethird electrode disposed between the electrode plates is clearly shown.

Figure2 shows a top view ofthe practical device.

Figure 3 shows the practical design of the device, with one-half of the top-cover removed.

Figure 4 shows a cross-sectional view of the practical device shown in Figure 3, and as indicated by the cross-sectional arrows.

Figure 5shows a bottom view of the practical device where the electric connecting electrodes are shown at the bottom of the cylinder.

Figure 6shows a cross-sectional view ofthe bottom view shown in Figure 5, as indicated by the cross-section arrows.

Figure 7shows an exploded view of the device, where the various parts are clearly indicated.

The invention is basically illustrated in Figure 1.

The device is basically composed ofthree metal electrode plates 1,2 and 3, which are Vee-shaped.

Plate electrodes 1 and 2 are electrically connected to the alternating current lines 6 and 7. The plate electrode 3 shall, hereinafter, be known as the "Ground Voltage-Null Control Electrode". The plate electrodes 1 and 2 are connected to the lines 6 and 7 respectively, such that the Ground Voltage-Null Control Electrodes 3, or for brevity, the "Control Vees" separate the Vee-Plates 1 and 2.

The Control Vees 3 are connected electrically to the wallsofthewater-containing vessel 5 by means of the contact electrode 4 and rivets passing through holes 13, as shown in Figures 1 and 2, respectively.

Electrode 4 is the central connecting electrode to which all Control Vees 3 are mechanically and electrically attached.

Alternating current lines 6 and 7 are supplied through a line distribution transformer 12; the secondary winding 10 is center-tapped, and this tapped connection 8 is electrically connected to "Earth-Ground" 13'. The primary winding 11 is actually supplied through a high tension transmission line system.

The Control Vees 3 are mechanically connected in such a mannerthatthey are located precisely at the equi-distant line between the Vee-Plate electrodes 1 and 2. Fu rthermore, the Control Vees 3 are electrically connected to the water vessel's metallic wall 5, thus making it possible to create a physical condition on the vessel wall of a floating earth-ground potential (as shown by the dashed earth 13").

The basic working principle involved may be briefly described as follows: The Vee-Plate Electrode Assembly is submerged in a vessel of water When the alternating current is switched on, the water contained between the Vee-Plates 1,2 and 3 electrically conducts. The electrical resistance ofthewater, at normal temperature, is about 5,000 ohms. Depending on the degree of impurity of the water, electric current conduction approaches a maximum at the boiling temperature. The electric power dissipation 12R (I electriccurrentand R = water resistance) increases rapidly with the decreasing resistance of the water itself. As the boiling point of the water is reached, the electric current flow approaches a maximum level.

Hence, electric power dissipation is efficiently transferred to the conduction medium -the water itself- causing it to rapidly vaporized into steam.

The method is known to be the most effective and efficient method of converting electric energy into heat energy in the form of steam. This invention eliminates the presence of an electric voltage between the water and the earth-ground. In other words, the 1 volts potential existing underthe conventional system is effectively balanced to the lowest minimum range of from zero to 6 volts, depending on the accuracy in the adjustment of spacer-plate 15 (Figure 2.) The simple solution to this problem is based on the fact that in an alternating current distribution system, the secondary winding 10 of the line distribution transformer 12 is center-tapped; and this center-tap is connected to the earth-ground.This is the reason why a 110 volt electric shock is often experienced by anyone who happens to touch either ofthe 220 volt distribution line wires.

As illustrated schematically in Figure 1, the Vee-Plate electrodes 1 and 2 are connected to the 220 volt lines 6 and 7. The Vee Control Electrode 3 lies along the equi-distant line between the Vee-Plates 1 and 2. This is the center potential of the 220 volt supply, that is, 1 volts with respect to the lines 6 and 7. Nowsince, as shown in Figure 1,the secondary center tap 8 connection is earth-grounded, the electric potential of the Control Vee-Electrode is atthe same polarity as the earth-ground potential; hence is equal to zero with respectto the earth-ground. Electrically, the water as weli as the vessel's wall areatthefloating earth-ground potential.

Evidently, underthis method the conventional ground wire provision to prevent electrical shocks to the users of the device is completely eliminated. How this is achieved practically is illustrated in Figures 2 to7.

Broadly, a heating module is adapted to be fitted in the bottom of a water vessel 30 (Figure 7). A base 21 is fitted in a hole in the water vessel and a circular container holding the electrodes is plugged into the base and retained therein. The container consists primarily of a base plate 24 and a perforated top cover 19, both made of a material with good insulating properties.

In Figure 2,the Vee-Plates 1,2 and 3 are mounted at 45 degree angles, for an eight element structure; or less than 45 degrees for more than eight elements.

To achieve perfect spacing between the three electrodes, a spacer plate 15 is sandwiched between theVee-Plates 1,2 and 3 atthe base plate 24(Figures 3 and 4). This spacer is made of some kind of thermoplastic with a good electric insulation property. Power connections to Vee-Plates 1 and 2 are made by means of brass-rod electrodes 17.

In Figures 4 and 6 are shown how these brass-rod electrodes 17 are mounted to the bottom or base-socket assembly 21, composed of parts 20 and 22. Part number 20, is a female cylindrical socket into which a connecting electrode (prong) 17 is plugged-in.

These male connecting electrodes (prongs) are alternately mounted to two plates 25 and 26, by inserting them in the sockets 20, as shown in Figures 5 and 6. The floating earth-ground connecting electrodes are provided to effectively connect the Ground-Voltage Control Vees 3 to the metallic wall of the water vessel or tank.

Figure 6 shows a cross-section of the steam generator assembly. The Vee-Plate Electrodes 1 and 2 are mounted on top ofthe base plate 24. The Vee-Plate assembly is plugged into the base-socket 21, and mechanically held tightly by means of plastic screw 18 which is threaded at the lower end 23, as shown in the exploded view of Figure 7. Part 19 is a top-coverforthe whole Vee-Plate Assembly. Part number21 isan octal socket designed to connect eight prongs of the heater assembly 24 by means of screw-type rods 17 and which provides an electrical connection for Vee-Plate electrodes 1 and 2.

The octal socket 21 is mounted to the water vessel 30 by means nut22 and is made waterproof by means ofthe rubber-washer seals 28 and 29.

The water vessel 30 is electrically connected to the Ground Voltage Control Vees by means of an electrode riveted through four holes 13. These electrode rivets electrically couple the water in the heater assembly 24 to the water vessel wall 30; hence making the electric polarity of the vessel wall equal to the floating earth-ground potential; and, therefore, the potential equals zero with respect to earth-ground.

In this specific practical design, Figures 2 and 3, there are eight assemblies of Vee-Plates 1,2 and 3.

More than eight elements may be designed, depending on the specific technical requirements from time to time. The assemblies are mechanically isolated by means of a two-thin-wall configuration 14madeofan insulating material upstanding from the base plate 24, as shown by the practical design in Figure2 (top view).

Referring to Figure 3, the top cover 19 (with half portion removed to show the Vee-Plate Assembly) is provided with circular holes 31 arranged in such a manner that they are a bove the radial Iy oriented assemblies of the Vee-Plates. The steam generated by the boiling water contained between the Vee-Plates 1 and 2 can readily escape through these holes31.

This water heaterand steam generator invention offers the following physical and electrical advantages over the conventional systems: 1. It provides instantboiling ofthewaterand steam generation since the water itself directly absorbs the electrical energy by acting as the heating element by means of the 12R dissipation.

2. It is capable of attaining the highest electrical energy-to-steam (heat) energy efficiency, since heat is first evolved internally by the electrically conducting water molecules; hence heat losses inherent under the conventional thermal conduction systems do not physically occur. Energy is first utilized in converting water into steam before it is conducted through the surrounding media.

3. The device is generally adaptable to any steam-heater system; it can be mounted to any size ofwater-boiler configuration; and its rated working power can bedesignedto coverthe input power range of from 50 watts to 50 kilowatts per module.

For higher power ratings, several modules may be operated in parallel.

4. The device does not require the conventional grounding wire connection in orderto prevent electrical shocks due to a 110 volt potential existing between the device and the earth-ground. The whole device is at zero potential with respect to earth-ground.

5. The device does not require the use ofa conventional thermostatic switching system in order to prevent overheating, since the system's temperature never exceeds the boiling point of water; the water being the heating element itself physically acts as the "Self Regulating Thermal Device". When the water is completelyvaporized, electrical conduction ceases; power is automatically switched "off" when the water level becomes zero.

Claims (9)

1. Awaterheateradaptedto be powered byan a.c. supply comprising two lines balanced with respect to ground potential, comprising at least two electrode plates arranged to be connected to the respective supply lines and to be directly immersed in water to be heated, and a third electrode disposed between the electrode plates substantially along a central equipotential line in use, the third electrode being arranged to be connected to a conductive water container of the heater.

2. Awaterheaterasclaimed in claim 1 wherein said third electrode is Vee-shaped with the arms of the Vee disposed substantially along radial lines extending from a centre ofthe heater.

3. Awater heater as claimed in claim 2 comprising a plurality of said third electrodes disposed symmetrically around said centre with a said electrode plate on each side of each arm of each third electrode.

4. Awaterheaterasclaimed in claim3wherein said electrode plates are also Vee-shaped.

5. Awater heater as claimed in any preceding claim wherein the or each said third electrode is mechanically and electrically attached to a central connecting electrode connected to said conductive water container.

6. Awaterheaterasclaimed in any preceding claim, wherein said electrode plates and third electrode are maintained substantially parallel to and separated from each other by a plurality of spacer plates composed of an insulating material, said spacer plates being cut away to allow current flowto occur directly through the water.

7. Awater heater as claimed in any preceding claim comprising a heater module enclosing said electrode plates and third electrode and mounted within the water container, said heater module having a perforated cover.

8. Awaterheaterasclaimed in any preceding claim wherein a socket is mounted on said water container and said electrode plates are connected to the supply lines via rod electrodes which plug into said socket.

9. A water heater substantially as hereinbefore described with reference to the accompanying drawings.