Technical field

The present invention relates to a multifunction domestic station, to a device for powering the same with hydrogen and to a method of operating the same.

More particularly, the invention relates to a domestic station having the functions of electric generator, heat generator and device for the disposal of domestic wastes.

Background of the invention

Due to the increase in the sensitiveness to the problems of environment protection, in recent years a constant development has been observed in researches concerning processes and systems for the generation of the so-called "clean" energy, that is, processes and systems which do not use fossil fuels or other fuels generating polluting substances or substances that are harmful for health or difficult to be disposed.

In recent years, a development has also been observed in researches concerning processes and systems for high-efficiency energy generation.

For instance, a method and a device using a reaction chamber or combustor using water and heated oil for generating energy is disclosed in patent publication WO 95/23942. The prior art device includes a combustor arranged to generate a flame which is horizontally deflected into a conventional boiler trough a connection.

The inventor of the prior art publication has realised that the prior art combustor has some drawbacks.

Actually, the flame of the combustor, being deflected so as to act in the horizontally arranged boiler, is arranged to heat the connection outside the boiler to a greater extent than the boiler interior, thereby causing a high loss of heat that could otherwise be exploited.

Moreover, the connection between the combustor and the boiler is a possible source of danger for the operators, who can burn themselves in case of contact with the connection, which is incandescent in use.

It is the object of the invention to provide a multifunction domestic station, a device for powering the same and a method of operating the same, which have high performance and which can be industrially manufactured at low cost..

Description of the invention

In accordance with a first aspect of the invention, the station comprises a structure including a combustor in which an endothermic reaction of at least one fuel with water is exploited in order to generate high temperature thermal energy.

The combustor is configured so as to directly direct the thermal energy, for instance a vertical flame, towards utilisation devices, such as a boiler external to the combustor and/or a boiler internal to the combustor.

The provision of one or multiple boilers onto which the thermal energy generated within the combustor is directly directed allows attaining a particularly high efficiency, without heat losses.

The combustor or reaction chamber is connected to a source of a pressurised mixture of water and air and at least to a source of a first fuel capable of endothermically reacting with the mixture.

The domestic station further includes heating devices for heating the first fuel to a combustion temperature in order to prime the reaction.

According to a first embodiment of the invention, the source of the first fuel, which is a vegetal or mineral oil, preferably exhausted, is connected to the reaction chamber both during a reaction priming phase and during a reaction maintaining phase, so that a reaction between the exhausted oil and the water - air mixture takes place in both phases.

According to another embodiment of the invention, the station also includes a source of a hydrogen-containing second fuel, which source is connectable to the reaction chamber, during the reaction maintaining phase, in the alternative or in addition to the source of the first fuel.

In accordance with another aspect of the invention, the station includes a hydrogen generator utilisable as the source of the second fuel. The generator comprises one or more units, each including:

- a chamber for the electrolytic decomposition of water, the chamber being internally equipped with a plurality of elements of conductive material, which are electrically connected in series with one another and with a pulsed voltage generator; and

- a pressurised container, connected on the one side to the decomposition chamber for receiving therefrom water, hydrogen and other products of the electrolytic decomposition and for introducing again pressurised water into the chamber, and connected on another side to the reaction chamber of the station in order to feed the chamber with hydrogen and the other products of the electrolytic decomposition.

According to a preferred embodiment of the invention, the pulsed voltage generator includes a d.c. voltage source, such as a battery or an accumulator, connected to a generator of a sawtooth voltage.

In accordance with a further aspect of the invention, a method of operating the station comprises bringing a pressurised mixture of water and air into contact with a fuel capable of endothermically reacting with the mixture, after the fuel has been heated to a combustion temperature in order to prime the reaction between the fuel and the mixture.

In a reaction priming phase the fuel is a vegetal or mineral oil, preferably exhausted, and in a reaction maintaining phase the fuel either can be the oil or it is hydrogen (more precisely, a hydrogen-containing fuel) or an oil - hydrogen mixture.

Brief Description of the Figures

Further features of the invention will become apparent from the following description of preferred embodiments, given by way of non limiting examples with reference to the accompanying drawings, in which:

- Fig. 1 is a principle diagram of a station according to the invention;

- Fig. 2a is a principle diagram of a variant;

- Fig. 2b is a schematic representation of the station shown in Fig. 2a; and

- Fig. 3 is a diagram of a hydrogen generator utilisable in the invention.

Description of Preferred Embodiments

Referring to Fig. 1, the multifunction domestic station according to the invention, generally denoted by reference numeral 1 , includes a reaction chamber or combustor 11 equipped with an exhaust terminal 11a at an upper end of the chamber. A strongly endothermic reaction takes place in chamber 11 between water, preferably source water at ambient temperature, and a preheated fuel. In this embodiment, the fuel is an oil (either a vegetal oil, for instance seed oil, olive oil and so on, or a mineral oil, for instance oil for engines or hydraulic oil), which is preferably exhausted so as to limit its cost.

Chamber 11 is preferably shaped as a frustum of a cone or a pyramid with square base and has exhaust terminal 1 la at its top end. Such a structure assists in maintaining the water - fuel reaction within the chamber upon multiple reflections, thanks to the kinetic energy generated, so as to create a rotating fire ball which does not leave immediately the chamber through exhaust terminal 11a and therefore has the necessary time to burn possible residuals of the endothermic reaction, thereby drastically reducing or eliminating them and/or raising at the same time the operating temperature of the chamber.

In any case, the chamber might also be prismatic, without thereby departing from the scope of the invention as described and claimed, and it may preferably have a base size in the range 15 x 15 cm to 200 x 200 cm and a height in the range 15 cm to 200 cm. The endothermic reaction preferably generates a flame that, in all embodiments, vertically leaves the chamber through exhaust terminal 11a.

The fuel is contained in a tank 12, for instance a gravity tank with an electrically operated valve 12a, and is preferably sent to reaction chamber 11 by means of a pump 13.

Tank 12 is moreover associated in conventional manner with level detectors 22, arranged to monitor the filling level of tank 12 and to operate an external pump (not shown) when it is necessary to supply again the tank with fuel. Other level detectors 23 are advantageously associated with reaction chamber 1 1 and are arranged to act on pump 13 so as to keep the fuel level within chamber 11 between a minimum and a maximum ensuring the optimum station operation. Taking into account that the reaction generates very high temperatures, as it will be better disclosed below, detectors 23 can for instance include a laser device arranged outside chamber 11 , or they may be detectors immersed in the fuel.

Reaction chamber 11 is further associated with two burners 14, 15. The first burner 14 (priming burner) is a conventional burner, for instance an oil or gas burner, and is to preheat the oil at such a temperature as to cause combustion thereof. The second burner 15 (reaction maintaining burner) is instead to send a pressurised water - air mixture, typically at a pressure of the order of 0.5 - 1 bars, into reaction chamber 11 after oil firing. In the alternative, burner 15 may be replaced by a compressed air ejector, operating at a pressure of a few bars, for instance 3 - 4 bars, and it is associated with a Venturi for air suction.

Two operation phases are therefore provided. In the first phase (priming phase), oil is brought to a combustion temperature that will depend on the particular kind of oil being used and, generally, will be in the range of about 350°C to 450°C. In the second phase (reaction maintaining phase), the water - air mixture is introduced into chamber 1 1. When the mixture comes into contact with the burning oil, a strong reaction at very high temperature occurs, resulting in water dissociation and consequent development of atomic and molecular hydrogen, oxygen and H ⁺ and OH ^" ions, as experimentally verified by the inventor.

An explanation of this behaviour could be the occurrence of a mechanical effect combined with different levels of sequential reactions and expansions at atomic level inside chamber 11, which effect creates an actual thrust in exhaust terminal 11a with a temperature, measured in open air, of about 1500°C - 1600°C and a noise of 100 - 120 db, as experimentally verified by the inventor. The noise and the exit pressure of the reaction products will obviously depend on the size of exhaust terminal 11a. A confirmation of the hypothesis of occurrence of a reaction at the atomic level and not of a chemical reaction is given by the emission of UV radiation noticed during the experimental tests.

Due to such high temperatures, polluting substances are practically absent, or are present in negligible amounts, in the gases produced by the combustion and leaving the chamber through exhaust 11a. Measurements carried out by the inventor have actually shown that C0 ₂ and nitrogen oxides NO _x are present in amounts of a few parts per million (2 - 3 ppm for C0 ₂ , 5 - 10 ppm for NO _x ):

Devices for utilising the thermal energy, denoted in the whole by reference numeral 16, are directly connected to exhaust 11a of combustion chamber 11, said devices being configured so as to exploit the thermal energy produced by the reaction.

More particularly, devices 16 may include a steam producing device (boiler) 17, followed by a conventional turbine 18 (in this case, a steam turbine) made to rotate by the steam produced in boiler 17. Turbine 18 is in turn connected for instance to one or more alternators 19 for generating electric power for domestic use, for instance at 3 to 5 kW/h per generator.

In accordance with a variant of the embodiment deemed as preferred, a second boiler 17a is located inside reaction chamber 1 1. Such an embodiment allows a double exploitation of the energy generated by the endothermic reaction.

In alternative or in addition to the devices connected to exhaust 11a, devices 16 could include a heat exchanger 20, for instance a coil surrounding reaction chamber 11, for heating water to be used in a heating plant, as sanitary hot water for domestic use etc.

In accordance with yet other embodiments, the steam generated in the boiler, for instance the steam generated in the first boiler 17 and used to drive turbine(s) 18, upon being condensed into water and before being sent to a collecting container, is used for being applied in heating plants, for instance plants with radiators, or for producing hot water, and then is cooled through a heat exchanger before entering the water supply container for boiler 17.

Preferably moreover, a drawer or other container 21 is inserted between reaction chamber 11 and boiler 17, said container (of course made of a material resistant to the high temperatures mentioned above) being arranged to contain domestic wastes, in particular wastes that cannot be subjected to differentiated collection and hence recycled,. Preferably, the drawer is arranged inclined towards a grate exposed to the flame so that the wastes, exposed to the high temperatures generated by the reaction, burn substantially without emitting polluting and poisonous substances, such as dioxin, and with a negligible emission of the above-mentioned C0 ₂ and NO _x . The station can therefore also be used as a domestic waste-to-energy plant.

Figs. 2a and 2b show a second embodiment of the invention, denoted 1A. The elements already disclosed with reference to Fig. 1 are denoted by the same reference numerals.

In this second embodiment, oil coming from tank 12 is still used as the fuel in the reaction priming phase, whereas oil, or an oil - hydrogen mixture, containing for instance 70% oil and 30% hydrogen, or yet only hydrogen can be used as fuel in the reaction maintaining phase. Hydrogen is produced for instance by at least one hydrogen generator 25.

In case of use of a fuel containing the mixture of oil, for instance exhausted oil, and hydrogen, the inventor has noticed a yield 50% higher than that attainable when using only oil as the fuel.

Simultaneous use of both fuels allows arranging at least two electric current generators or alternators 19 at the output of boiler 17, for instance by connecting a pulley arranged to operate the alternators by means of toothed wheels to turbine 18.

In case hydrogen is used as fuel in the maintaining phase, electrically controlled valve 12a is closed thereby isolating tank 12 from reaction chamber 11 , pump 13 is not operated, and hydrogen and the pressurised water - air mixture are sent to chamber 11.

Preferably, at least a pair of identical generators 25 is provided, as shown in Fig. 2a. Assuming for instance that two generators are provided, one of them can be a stand-by generator, arranged to intervene in case of failure of the other generator. The generators can however be used in alternating manner, according to a suitable timing, or jointly, for instance to meet peaks of power demand.

In all embodiments, devices arranged to detect the value of the flame temperature in reaction chamber 1 1 can be preferably provided. Such devices can be connected to means for automatically turning off the station in case of anomalous operation.

Preferably, the station comprises a control panel including, for instance, instruments for measuring temperature and pressure values in the various components of the station.

Moreover, for safety reasons, non-return valves, pressure switches and other safety devices might also be provided in the station.

The structure of generator 25 is shown in greater detail in Fig. 3.

The generator comprises a chamber 30 for the electrolytic decomposition of demineralised water, with a duct 21 for supplying the demineralised water, made conductive preferably by the addition of alkaline metal compounds, preferably hydroxides of such metals, in particular sodium hydroxide or, in the alternative, potassium hydroxide.

The water might also contain concentrated hydrogen peroxide added in a percentage of up to 50%, for instance 10 to 50%>. The addition of hydrogen peroxide allows increasing the amount of hydrogen produced for a given size of chamber 30.

A set of elements 32 of conductive material, for instance stainless steel and/or titanium, are arranged within chamber 30. Elements 32, for instance discs or plates

("discs") are coaxially mounted on one or more rods 33 (for instance a central rod, as shown in the Figure, or a plurality of rods distributed along the periphery of discs 32) and are separated by spacers 34, for instance a few millimetres thick (e.g. 1 - 2 mm thick).

Discs 32 have a slightly smaller size than chamber 30 and define with the side walls of the chamber a substantially serpentine path for water.

Preferably, the serpentine path for water is obtained by inserting, at the end of each disc 32, suitable sealing rings or components 32a of plastic material, e.g. Teflon, fastened to decomposition chamber 30, and by providing one or more throughholes 52 on each disc

32, the holes in adjacent discs 32 being located in diametrically opposed positions.

Discs 32 are electrically connected in series with one another and with a generator of d.c. voltage, for instance a battery or accumulator 41 (typically, a motor-car battery with 12 V nominal voltage or an industrial vehicle battery with 24 V nominal voltage), and a wall of chamber 30, in particular roof 30a, serves as the ground. The voltage source is such as to establish a same voltage difference, in particular a voltage difference of about 2

V and preferably in the range 2.1 to 2.35 V, between a first disc 32 in the plurality and ground 30a and between adjacent discs 32. With such values of the voltage difference, at least six discs 32 are provided, since a nominal voltage lower than 12 V does not allow a good operation of the generator. The actual number of the discs will depend on the voltage generated by battery 41.

Means 42 are arranged between battery 41 and the set of discs 32 for converting the d.c. voltage generated by battery 41 into a pulsed voltage, for instance a sawtooth voltage having a maximum value corresponding to the nominal voltage of the battery, whereas the minimum value can preferably be in the range 40% to 50%, and preferably is about 50%, of such a nominal voltage.

Such a pulsed voltage causes the formation on the surface of discs 32, due to water decomposition, of small hydrogen bubbles the sizes of which increase as the voltage applied to the individual discs increase (and hence as water proceeds within chamber 30 by following the serpentine path).

At the end of the serpentine path, in correspondence with the last disc 32, the small hydrogen bubbles attain, due to the surface tension, such sizes that they can detach themselves from the surface of the same disc. The above-mentioned voltage difference of about 2 V between adjacent discs is the optimum value for creating those bubbles.

Water and the products of electrolytic decomposition (hydrogen, oxygen and H ⁺ and OH ions) leave chamber 30 through a duct 35 and are fed to a pressurised container 37 (for instance at 2 - 3 bars), possibly through a radiator 38 arranged to cool the products of electrolytic decomposition.

In the alternative, especially in case of small plants, cooling can be performed by means of d.c. powered cooling fans, for instance of the kind used in personal computers.

Gaseous products and ions, which are more volatile, leave container 37 through a top duct 39 leading to reaction chamber 1 1 (Figs. 1 , 2a, 2b), whereas demineralised water is introduced again under pressure into electrolytic decomposition chamber 30 through a bottom outlet duct 40 and a pump 36.

In accordance with a constructional variant of generator 25, a proton accelerator, for instance of the kind disclosed in patent publication WO 2007/119141 A in the name of the inventor, is located at the exit from top duct 39 leading the hydrogen compound from the generator to combustion chamber 1 1. Said accelerator is capable of increasing the yield of generator 25, as experimentally verified by the inventor,

In an advantageous embodiment, the gases are heated before being introduced into reaction chamber 11 (for instance by using coil 20 mentioned above), thereby creating a pressure and volume increase and a stronger suction of the same gases. In this case, duct 39 will have to be associated with a non-return valve (not shown), for preventing hydrogen and the other products of electrolytic decomposition, which have undergone the pressure and volume increase due to the heating, from going back into container 37.

Sending the products of electrolytic decomposition into reaction chamber 1 1 facilitates the high temperature reaction.

Taking into account the description of generator 25, it is pointed out that, when the use of hydrogen as fuel has been referred to in the description of the station, the term "hydrogen" denotes, more generally, the whole of the products of the electrolytic decomposition of water.

It is to be appreciated that, due to the use of the alkaline metal compounds, the components of generator 25 are not to contain aluminium, which would be attacked by said compounds.

The advantages afforded by the invention are clearly apparent from the preceding description.

The basic reagents are cheap (essentially water, alkaline compounds and exhausted oils) and hence the whole process and the station can be carried out/manufactured and managed in economical manner.

The very high temperatures attained allow attaining high performance. Moreover, as said, at the temperatures indicated, the reaction fumes contain negligible amounts of polluting substances.

Using exhausted oils as fuel at least in the reaction priming phase also contributes to the disposal of such oils.

Moreover, the possibility of using the station as waste-to-energy plant assists in eliminating wastes that cannot be recycled.

Furthermore, it is not to be neglected that the management costs of the domestic station as described are extremely low thanks to the use of liquid fuel of little value, such as exhausted oils, and/or of gases obtained from the decomposition of demineralised water, which in turn is a cheap resource.

Moreover, advantageously, the station can be configured so as to allow, for instance, heat production, electric power production and waste disposal.

In synthesis, a domestic station is provided that can be installed in every house as a one-family plant or as a central plant, for instance a condominium plant, in order to provide a plurality of services at very low cost.

By summarising, the station of the invention is actually a completely autonomous and stand-alone equipment and not only a component of a more complex system.

It is clear that the above description has been given only by way of non-limiting example and that changes and modifications are possible without departing from the scope of the invention as defined in the following claims.