Hydrogen supply unit

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Background of the invention

THIS i n v e n t i o n relates to hydrogen generation.

It has already been proposed to replace conventional fuels with hydrogen in the running of internal combustion engines. Conventional proposals are to produce hydrogen by the electrolysis of w a t e r and then to store the hydrogen in some form or a n o t h e r . No e c o n o m i c a l l y viable storage system for the highly explosive hydrogen gas has y e t been evolved. Whatever system is evolved would involve fairly massive tanks of some kind or another and precautions to prevent.-explosions.

The p r e s e n t invention is based on the desire of the inventor to be able to provide hydrogen on demand from m a t e r i a l s which are in them-

Summary of the invention

According to the invention a method of generating hydrogen comprises the steps of exposing a fresh metal surface to w a t e r and heating the interface between the metal surface and the water at least to the lowest temperature at which the metal reacts with water to form a metal oxide and hydrogen, the metal being chosen from m e t a l s which are higher in the electromotive series than hydrogen and having stable and safe handling characteristics.

Preferably the metal surface is exposed and the interface heated by pressing an e l e c t r o d e of the relevant metal against a second electrode 3 under water and applying a high voltage.between the electrodes while, preferably, moving the electrode surfaces relatively to one another.

In o t h e r words in the preferred form of the invention hydrogen is formed by c r e a t i n g an underwater electrical discharge between two electrodes at least one of which is made of a metal as defined above.

The e l e c t r i c a l discharge and the relative movement between the electrode surfaces ensure that fresh metal surfaces are exposed to the water while at the same time the discharge heats the interface between the electrodes and the water to the required temperature at which the metal reacts with water to form its oxide and to liberate hydrogen.

Also in the preferred form of the invention the metal is aluminium which has the advantage that it is in relatively abundant supply, relatively cheap, is formed with a protective oxide layer on i t s exposed surfaces and reacts with water at a relatively low t e m p e r a t u r e . Aluminium wire fed against a rotating aluminium drum has been found to give excellent results to provide hydrogen for powering small internal combustion engines.

A convenient way of securing the high voltage required is to empl-oy the conventional distributor and coil arrangement which provides the sparking for an internal combustion-engine. Two c o i l s in parallel fed from a common d i s t r i b u t o r has been found to give excellent results. Other methods of generating high voltages from the battery or the drive shaft of an internal combustion engine may a l s o be u s e d .

The method of the invention lends itself in an e x c e l l e n t manner to supply hydrogen on demand. In t h i s case hydrogen is fed to a small buffer store and as the pressure in the store exceeds a predetermined level, the electrodes are separated so t h a t hydrogen generation is 4 interrupted. As the pressure drops to a certain level the electrodes are again fed towards one another.

Brief description of the drawing

The invention will now be f u r t h e r described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a schematic representation of apparatus for generating hydrogen, and suitable for powering a motor vehicle; and Figure 2 shows a portion of an a p p r o p r i a t e electrical circuit.

Description of a preferred embodiment

In the illustrated embodiment there is a generating tank 10 f e d with water from a r e s e r v o i r tank 11 t h r o u g h a float valve 12 to keep the w a t e r level 13 in the tank 10 s u b s t a n t i a l l y constant. When the apparatus is used in a motor vehicle, the tank 11 can take the place of the conventional fuel tank of the vehicle with a pump 14 in the line 15 to. pump more water into the tank 10 when the position of the float 12 i n d i c a t e s that this is required. Water is consumed as hydrogen is generated, and so the tank 1 1 has to be p e r i o d i c a l l y refilled. The g e n e r a t i n g tank 10 is in communication with an a i r cooled heat exchanger 16, which may take the same form as a c o n v e n t i o n a l motor car radiator.

The g e n e r a t i n g tank 10 is surmounted by a c o l l e c t i n g v e s s e l 17 from which hydrogen is drawn through a restricted orifice 18 of an i n t e r n a l combustion engine. Inside the tank 10 t h e r e is a drum 19 d r i v e n by any s u i t a b l e means to rotate at a constant speed. The drum 19 is made of a l u n i n i u m . A depending flange 20 p r o v i d e s a water seal to the top left hand corner of the tank 10, so t h a t that corner is not in gas communication with the

A coil 21 of aluminium wire 22 is fed through a push-pull unit 23 o f t h e kind used to feedwelding wire to argon arc welding devices. The u n i t 23 is arranged to feed the wire against the surface 5 of the drum 19 and to traverse the wire along the length of the drum on a bar 24. The wire passes along an insulating sleeve 25 which enters the tank 10 t h r o u g h a suitable wiper seal.

In the vessel 17 t h e r e is a pressure sensor 26 c o n n e c t e d to a control unit 27. When the pressure sensor senses a pressure above a predetermined value,it signals the control unit 27 which in turn stops the unit 23 so t h a t wire is no l o n g e r fed towards.the drum 19. When the pressure drops again, feeding is resumed.

In use, the coil 21 is connected to the high tension side of two ignition coils or transformers 30 and 33. These transformers have primary windings 31 and 34 and secondary, high tension windings 32 and 35. A capacitor 36 is connected across the high tension connections. The t e r m i n a l s 28 and 29 are connected to

At the point of contact between the end of the wire 22 and the drum 19 an e l e c t r i c a l discharge takes place. As a r e s u l t the adjacent metal surfaces are heated to a high temperature, the protective oxide film which naturally forms on exposed aluminium surfaces is disrupted; and the exposed aluminium surfaces react with the water. In.fact the electrochemical situation at the interface is such that the wire 22 is consumed, with the following

As a r e s u l t , hydrogen bubbles from the contact point while the aluminium oxide collects as a white powder in the base of the tank 10. A grid 37 in the bottom of the tank allows the powder to pass through, and then keeps the powder substantially free from c u r r e n t s in the tank 10. The hydrogen passes-through the vessel 17 and the orifice 18 to the carburettor of an i n t e r n a l combustion engine.

There may be a t e n d e n c y for bubbles of hydrogen to adhere to the surface of the drum 19 which rotates in the direction indicated by the arrow 38. To p r e v e n t this happening, a wiper blade 39 6 can be l o c a t e d in the position shown in Figure 1, so as to separate any a d h e r i n g bubbles from the drum s u r f a c e .

Alternatively, a wiper blade 40 may be a r r a n g e d on the opposite side of the drum. In t h i s case a small volume of hydrogen gas may c o l l e c t beneath this blade, and it may be p o s s i b l e to pivot the blade 40, thus releasing this pocket of hydrogen in o r d e r to facilitate startup of an engine fueled by the hydrogen.

It may be p o s s i b l e to use salt water in the tank 10, rather than fresh water.

The drum 19 p r e f e r a b l y rotates at a speed between 400 and 700 rpm, but the rotation may be as slow as 50 rpm.

During operation, the temperature of the water in the tank 10 may rise as high as 95°C, although it is likely that a unit mounted in a moving vehicle, for example, wili be a b l e to maintain the water at a lower temperature.

A unit substantially as shown in the drawings has been used to drive a 500cc motor cycle engine. The wire 22 had a d i a m e t e r - o f 1,6 mm and was of commercial purity (98%Al). The unit produced over 1000 cc o f hydrogen a minute, with an aluminium wire consumption rate of 140 to 180 cm per minute.. Therate of d e p o s i t i o n of aluminium oxide was about 4 kilograms per 500 kilometers travelled:

Conventional modifications were made to the carburettor to enable the engine to run.on a mixture of hydrogen and a i r .

The wire 22 c a r r i e s a voltage of about 18000 volts with a current

Drawings

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Apparatus for generating hydrogen comprising a tank (10) for containing water, a metal surface (22) arranged in the tank, means for heating the surface at least to the lowest temperature at which the metal reacts with water to form a metal oxide and hydrogen, and a chamber (17) for collecting the generated hydrogen.

Apparatus as claimed in Claim 1, wherein the metal surface (22) is aluminium.

Apparatus as claim in Claim 1 or Claim 2, wherein the means for heating the surface is an e l e c t r i c a l discharge between the surface (22) and

Apparatus as claimed in Claim 4, wherein a second metal surface (19) is arranged in the tank, and means are provided to move one surface (19) relative to the other, the two s u r f a c e s being connected in an e l e c t r i c a l circuit (Figure 2) so t h a t they form electrodes between which an electrical discharge can take p l a c e .

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Apparatus as claimed in Claim 4, wherein the second metal surface is

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Apparatus as claimed in Claim 4 or Claim 5, wherein the first metal surface (22) is a wire and the second metal surface (19) is a drum, the drum being mounted for rotation and the wire being supported so - that it approaches the cylindrical surface of the drum at an angle to

Apparatus as claimed in Claim 6, wherein the wire (22) is supported by a device (23) which continuously feeds the wire, as it is consumed,

Apparatus as claimed in Claim 7, wherein means (26,27) are provided for sensing the pressure of hydrogen gas in the chamber (17) and for regulating the feed rate of the wire feeding device (23) in accordance with the sensed pressure, to control the hydrogen output.

Apparatus as claimed in any preceding claim, wherein the tank (10) is connected to a heat exchanger (16), so t h a t water can circulate from the tank, through the heat exchanger, and back to the tank.

A method of g e n e r a t i n g hydrogen comprising the steps of e x p o s i n g a fresh metal surface (22) to water and h e a t i n g the interface between the metal surface and the water at least to the lowest temperature at which the metal reacts with water to form a metal oxide and hydrogen, the metal being chosen from m e t a l s which are higher in the electromotive series than hydrogen and which have stable and safe handling characteristics.

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A method as claimed in Claim 10, wherein the metal (22) is aluminium, and a f r e s h metal surface is exposed and the interface heated by pressing an aluminium electrode (22) against a second electrode (19) under water and a p p l y i n g a high voltage between the electrodes.

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