AU2012261768B2 - Hydrogen Generation - Google Patents

Abstract

Abstract A system for generating hydrogen by the electrolysis of water is disclosed. Designed for use within a vehicle, the system promotes the turbulent flow of water past electrode plates to increase efficiency of the electrolysis reaction.

Description

“HYDROGEN GENERATION”

Field of the Invention [0001] The present invention relates to the production of hydrogen gas for use within an internal combustion engine.

Background to the Invention [0002] The use of hydrogen gas as a fuel in its own right is well known, with a range of technologies such as fuel cells being based on hydrogen gas. It is less well appreciated that the introduction of hydrogen gas as an additive to gasoline-fuelled internal combustion engines can also have significant beneficial effects. In particular, the introduction of hydrogen gas improves the burn efficiency within a combustion engine, reducing the amount of unburnt hydrocarbons and also reducing carbon monoxide emissions.

[0003] Storage of hydrogen gas in a passenger vehicle can be problematic, and particularly so when it must be stored alongside hydrocarbon based fuels. It is thus proposed to generate hydrogen via electrolysis of water, using electricity produced by the vehicle alternator.

[0004] The present invention seeks to provide an efficient method and apparatus by which such hydrogen gas can be produced for usage within an internal combustion engine.

Summary of the Invention [0005] According to one aspect of the present invention there is provided an apparatus for the production of hydrogen by electrolysis, the apparatus including at least two electrodes; an electrolyte pump; and a turbulence inducing means, whereby an electrolyte undergoing electrolysis is caused to move past the electrodes in a state of turbulent flow. It is believed that the turbulent flow assists to increase the diffusion coefficient of the electrolyte and also reduces the effective gap between ions in the electrolyte and the electrodes.

[0006] It is preferred that the turbulence inducing means is a flow restricting plate, the flow restricting plate including apertures through which the electrolyte can be accelerated and which act to promote turbulent flow. The flow restricting plate also acts to increase pressure on an up-stream side of the plate.

[0007] It is preferred that the electrodes are formed by substantially vertical plates, with the flow restricting plate being substantially horizontal and located beneath the electrodes; that is, with flow of electrolyte through the apparatus being in a generally upward direction.

[0008] There may be a capping plate atop the electrodes, including apertures through which electrolyte passes for collection and re-use, and through which hydrogen and oxygen gas may pass for collection. It is preferred that the apertures of the capping plate are larger than those of the flow restricting plate, so as not to substantially restrict flow of the electrolyte.

[0009] In a preferred embodiment of the present invention the apparatus comprises six cells, each having two electrodes, arranged in an array.

[0010] In accordance with a second aspect of the present invention there is provided a method of generating hydrogen gas by the electrolysis of water, the method including the steps of forcing electrolyte to flow past electrodes in a state of turbulent flow.

[0011] It is preferred that the electrolyte be accelerated immediately before flowing past the electrodes.

[0012] It is anticipated that the electrolyte will consist of water. It is preferred that a chemical be added to the water to lower the surface tension. This may be a weak solution of potassium hydroxide, or alternatively sodium hydroxide, for instance a 2 molar solution. This acts to reduce the size of gas bubbles generated during electrolysis, reducing the reactance of the system and promoting more efficient hydrolysis.

[0013] It is also preferred that a protective chemical be added to the water in order to reduce electrolytic stripping of the electrodes. This chemical may be hydrogen phosphate.

Brief Description of the Drawings [0014] It will be convenient to further describe the invention with reference to preferred embodiments of the present invention. Other embodiments are possible, and consequently the particularity of the following discussion is not to be understood as superseding the generality of the preceding description of the invention. In the drawings: [0015] Figure 1 is a perspective of a hydrogen generating apparatus in accordance with the present invention; [0016] Figure 2 is a side view of the hydrogen generating apparatus of Figure 1; [0017] Figure 3 is a cross section of the hydrogen generating apparatus of Figure 1, taken through line J-J of Figure 2; [0018] Figure 4 is a cross section of the hydrogen generating apparatus of Figure 1, taken through line K-K of Figure 2; [0019] Figure 5 is a cross section of the hydrogen generating apparatus of Figure 1, taken through line L-L of Figure 2; [0020] Figure 6 is an enlargement of the area ‘A’ of Figure 5; [0021] Figure 7 is an enlargement of the area Έ’ of Figure 5; [0022] Figure 8 is a perspective of an electrode array within the hydrogen generating apparatus of Figure 1; [0023] Figure 9 is a perspective of a flow reducing plate within the hydrogen generating apparatus of Figure 1; [0024] Figure 10 is a perspective of an electrode plate within the electrode array of Figure 8; and [0025] Figure 11 is a spacer from within the electrode array of Figure 8.

Detailed Description of Preferred Embodiments [0026] Referring to the Figures, there is shown a hydrogen generating apparatus 10 including an electrolyte reservoir 12 and a generating unit 14. The electrolyte reservoir 12 includes an electrolyte supply line 16 located at the base of the reservoir 12, an electrolyte return line 18 located at the top of the reservoir 12, and an electrolyte replenishment line 20 located also at the top of the reservoir 12.

[0027] The generating unit 14 includes an electrolyte pump 22 located on an external wall of the generating unit 14. The pump 22 is arranged to receive electrolyte from the electrolyte supply line 16, and to pump it to an electrolyte injection line 24. The electrolyte injection line 24 feeds into a base of the generating unit 14.

[0028] A reaction chamber 26 is located internally of the generating unit 14. The reaction chamber 26 can best be seen in the cross sections of Figures 3 to 5. The reaction chamber 26 is located within an open box 27, which is preferably formed from insulating and chemical erosion resistant materials such as HDPE plastic. In the preferred embodiment shown the open box 27 includes neoprene seals mounted at both open ends.

[0029] The reaction chamber 26 of the embodiment shown consists of three electrolysis enclosures 28 arranged side-by-side. The electrolysis enclosures 28 are separated by separating plates 30. The separating plates 30 are sized to locate within the reaction chamber 26 in a vertical orientation, and to substantially prevent fluid flow between adjacent enclosures 28.

[0030] Each electrolysis enclosure 28 has two electrolysis cells formed by a plurality of electrode plates 32 arranged in an array parallel to the separating plates 30. In the embodiment shown each electrolysis cell has about three pairs of electrode plates 32. The arrangement is such that a first cell extends upwardly from a base of the electrolysis enclosure 28, and a second cell extends downwardly from a top of the electrolysis enclosure 28. The electrolysis cells may be interspersed. This is shown in Figures 6 and 7.

[0031] The electrodes may be arranged in precise orientation by the use of spacers 29 such as that shown in Figure 11. It will be appreciated that different spacers 29 having a varied pitch could be used for different applications. It is preferred that the spacers 29 are made of an inert material such as FIDPE plastic.

[0032] It will be appreciated that some or all of the electrolysis enclosures 28 can be modified to have a single electrolysis cell within, by a modification of the mounting of the electrode plates. The generating apparatus 10 as shown can therefore be arranged to constitute between three and six cells. This allows for modification to suit the particular requirements (such as battery/alternator capacity) of individual vehicles.

[0033] The electrode plates 32 are typically made from titanium or stainless steel 316, and are in the order of 1,2mm thick. It is preferred that that electrode plates 32 are made from high grade stainless steel with a relatively high molybdenum concentration.

[0034] It will be appreciated that the number and arrangement of electrode plates 32 within the confined space of the electrolysis enclosure 28 forces the electrolyte to pass the plates 32, preferably in a turbulent manner.

[0035] It is preferred that the plates 32 be spaced to produce a capacitive reactance in a fresh water electrolyte. A plate spacing of 2mm for 2100cm2 plates achieves this purpose, as does a plate spacing of 2.5mm for 4100cm2 plates.

[0036] A turbulence inducing means, being a flow reducing plate 34, is arranged horizontally across the base of the reaction chamber 26, beneath the electrolysis enclosures 28. The flow reducing plate 34, as seen in Figure 9, has a plurality of holes 36 spaced about it, the holes 36 being grouped beneath each of the enclosures 28. In a typical embodiment, there are 48 holes 36 beneath each enclosure 28, each hole 36 having a diameter of about 3mm. It is preferred that the holes 36 be angled (not like those shown in Figure 9) in order to encourage a flow of pressurised water through all parts of the reaction chamber 26. In this way, the holes 36 act as ‘jets’ to ensure that electrolyte enters the enclosure 28 at high speed. In a most preferred embodiment, the holes 36 are tapered from about a 6mm diameter to about a 3mm diameter in order to promote a stronger flow into the enclosure 28.

[0037] The reaction chamber 26 includes three electrolyte pressure chambers 38 located beneath the flow reducing plate 34, one chamber 38 being associated with each enclosure 28. The arrangement is such that the pressure chambers 38 are supplied with electrolyte via the electrolyte injection line 24 via a common rail, and that electrolyte flows from the pressure chambers 38 into the enclosures 28 via the holes 36 in the flow reducing plate 34. The effect is that the flow reducing plate 34 acts to increase the pressure in the pressure chambers 38, meaning that electrolyte is accelerated through the holes 36 into the enclosures 28 and is able to flow past the electrode plates 32 in a turbulent, fast flowing fashion. It will be appreciated that the use of a common rail ensures substantially equal pressure in each enclosure 28.

[0038] A capping plate 40 is located at the top of the reaction chamber 26. The capping plate 40 includes apertures significantly larger than the holes 36, through which electrolyte can flow substantially unimpeded. It will be appreciated that hydrogen gas and oxygen gas obtained by electrolysis of the electrolyte will also bubble through the holes of the capping plate 40, and can be collected in a gas collection area 42 located above the reaction chamber 26.

[0039] Electrolyte passing through the capping plate 40 is allowed to flow out of the generating unit 14 via a common rail and the electrode return line 18 to the reservoir 12. It will be appreciated that some electrolyte will return through the capping plate 40 to the reaction chamber 26, but that the apertures of the capping plate 40 will prevent the ‘backflow’ of hydrogen gas and oxygen gas bubbles.

[0040] The hydrogen generating apparatus 10 is arranged generally to allow for ease of servicing and for effective transfer of heat. For example, the pump 22 is mounted away from the generating unit 14 to allow both ease of access and good airflow. Similarly, the flow reducing plate 34 is mounted within the reaction chamber in such a way that it can be readily removed for servicing, such as the removal of blockages.

[0041] Additionally, the electrode plates 32 are mounted as a cartridge, as shown in Figure 8, for ease of replacement.

[0042] The pressure chambers 38 are connected to a flushing tap 44, which allows the system to be periodically flushed and contaminants such as ferrous hydroxide and chromium hydroxide to be removed.

[0043] The electrode plates 32 have a particular geometry as shown in Figure 10. The plates 32 are generally square, with an aperture 46 located in one corner and a central aperture 48. In addition, the electrode plates include cut outs 50 located at appropriate intervals about their edges. This geometry allows the ready mounting of electrode plates in a number of configurations, such as in to a single cell or double cell configuration, simply by appropriate arrangement of mounting bolts. The cut outs 50 at the plate corners are part circular, in order to reduce the charge concentration at the corners of the plates 32.

[0044] In use, the electrolyte reservoir 12 is filled with a suitable electrolyte. It is proposed to use water (pure water, rather than tap water containing calcium and iron) to which potassium hydroxide (resulting in a 2 molar solution) has been added. The potassium hydroxide acts to lower the surface tension of the electrolyte, which in turn reduces the size of gas bubbles generated and lowers the reactance of the system.

[0045] Additionally, hydrogen phosphate is added to reduce the stripping of the electrodes and to ensure that iron hydroxide and chromium hydroxide are not produced in the electrolytic reactions. Once a phosphate barrier is created on the cells, the solution may be flushed and replaced with a solution of dilute potassium hydroxide and sodium hydroxide (for instance, 11 grams potassium hydroxide and 5 grams sodium hydroxide per three litres of pure water).

[0046] It will be appreciated that the potassium hydroxide neutralises the acidity of the hydrogen phosphate.

[0047] In a preferred embodiment, the system may be etched using an electrolyte comprising 3 litres of water mixed with 11 grams of potassium hydroxide for a period of 30 minutes at 15 to 25 amps; then adding 25mls of phosphoric acid at a concentration of 185g / litre.

[0048] Once the electrolyte reservoir 12 is filled, the electrolyte is pumped by the pump 22 from the reservoir 12 through the supply line 16 and the injection line 24 into the pressure chambers 38.

[0049] From here the electrolyte is urged upwards through the holes 36 into the enclosures 28. The urging of the electrolyte causes it to travel upwards at a sufficient velocity to maintain turbulence along the entire face of the electrode plates 32.

[0050] Most efficient operation occurs when the electrolyte is maintained at between about 70°C and 90°C. This is achieved in the present embodiment by use of a forced convection system (the pump 22) and using a three litre reservoir 12. In the embodiment shown, the three litres of electrolyte in the reservoir 12 is in addition to two litres of electrolyte in the reaction chamber 26. The ratio of volume to surface areas of the cells is arranged so that at current of about 18 amps the system stabilises at a temperature around 75°C with an electrolyte consumption of about one litre each eight hours.

[0051] A venting pipe 54 is provided at the top of the hydrogen generating apparatus 10, ensuring that any gases which escape the apparatus 10 are vented to the exterior of the vehicle.

[0052] It will be appreciated that the hydrogen generating apparatus can be supplied as a stand-alone unit, allowing easy installation into any vehicle.

[0053] Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.

Claims (9)

1. Claims

   1. An apparatus for the production of hydrogen by electrolysis, the apparatus including at least two electrodes; an electrolyte pump; and a turbulence inducing means being a flow reducing plate, whereby an electrolyte undergoing electrolysis is caused to move past the electrodes in a state of turbulent flow, the flow restricting plate including apertures through which the electrolyte can be accelerated and which act to promote turbulent flow, the electrodes being formed by substantially vertical plates, with the flow restricting plate being substantially horizontal and located beneath the electrodes, and wherein there is a capping plate atop the electrodes, including apertures through which electrolyte passes for collection and reuse, and through which hydrogen and oxygen gas may pass for collection.
2. 2. An apparatus for the production of hydrogen by electrolysis as claimed in claim 1, wherein the apertures of the capping plate are larger than those of the flow restricting plate, so as not to substantially restrict flow of the electrolyte.
3. 3. An apparatus for the production of hydrogen by electrolysis as claimed in any previous claim, wherein the apparatus comprises six cells, each having two electrodes, arranged in an array.
4. 4. A method of generating hydrogen gas by the electrolysis of water, the method including the steps of forcing electrolyte to flow past electrodes in a state of turbulent flow using an apparatus as claimed in any preceding claim.
5. 5. A method of generating hydrogen gas as claimed in claim 4, wherein the electrolyte is accelerated immediately before flowing past the electrodes.
6. 6. A method of generating hydrogen gas as claimed in claim 4 or claim 5, wherein the electrolyte consists of water to which a chemical is added to lower the surface tension.
7. 7. A method of generating hydrogen gas as claimed in claim 6, wherein the chemical added is potassium hydroxide.
8. 8. A method of generating hydrogen gas as claimed in any one of claims 4 to 7, wherein a protective chemical is added to the water in order to reduce electrolytic stripping of the electrodes.
9. 9. A method of generating hydrogen gas as claimed in claim 8 wherein the protective chemical is hydrogen phosphate.