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Title:
PRODUCTION OF HYDROGENAND OXYGEN BY ELECTROLYSIS
Document Type and Number:
WIPO Patent Application WO/2019/155414
Kind Code:
A1
Abstract:
Electrolysis apparatus is disclosed which comprises two electrodes (24.1, 24.2) standing upright in a cylindrical casing filled with acidic electrolyte. Each electrode comprises a lead tube (10) sheathed in a cylindrical grid of synthetic plastics material (16) and a cylindrical perforated metal element (18). The electrodes are coated with electrochemically active material (28, 30). Tabs (14, 22) protrude from the tube (10) and element (18) and permit connection to an external circuit. The tubes are filled with an alkaline electrolyte.

Inventors:
HUMAN, Jan Peterus (10A Clifford Road, Chancliff, 1739 Krugersdorp, 1739, ZA)
Application Number:
IB2019/051022
Publication Date:
August 15, 2019
Filing Date:
February 08, 2019
Export Citation:
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Assignee:
HUMAN, Jan Peterus (10A Clifford Road, Chancliff, 1739 Krugersdorp, 1739, ZA)
International Classes:
C25B1/02
Domestic Patent References:
WO2016007983A12016-01-21
Foreign References:
US20050126924A12005-06-16
US2987463A1961-06-06
US3632497A1972-01-04
GB508524A1939-07-03
Attorney, Agent or Firm:
BRIAN BACON INC. (2nd Floor, Mariendahl HouseNewlands on Mai, Main Road 7700 Newlands, 7700, ZA)
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Claims:
CLAIMS:

1 . Electrolysis apparatus comprising a casing containing electrolyte, first and second spaced apart vessels each of which is of electrically conductive metal and has its outer surface in contact with the electrolyte in the casing, said vessels having electrolyte in them which gases at a lower voltage than the electrolyte in the casing, and outlets from said vessels for gases that are evolved when, in use, current flows through the apparatus.

2. Electrolysis apparatus comprising a casing containing electrolyte, first and second spaced apart vessels each of which is of electrically conductive metal and has its outer surface in contact with the electrolyte in the casing, said vessels having electrolyte in them which gases at a lower voltage than the electrolyte in the casing, there being outlets from said vessels for gases that are evolved when, in use, current flows through the apparatus, one of said vessels being coated externally with electrochemically active negative material and the other being coated externally with electrochemically active positive material.

3. Apparatus as claimed in claim 2 and comprising a grid of electrolyte resistant material externally of each vessel and a metal element with perforations in it adjacent said grid, the coating being on the outside of the metal element, in the perforations of the metal element in the interstices of the grid and in contact with the vessel.

4. Apparatus as claimed in claim 1 , 2 or 3 and including an electrolyte permeable separator between said vessels.

5. Apparatus as claimed in any preceding claim, wherein each vessel has a first part in contact with the electrolyte in the casing and a second part which protrudes from the electrolyte in the casing.

6. Apparatus as claimed in any preceding claim, wherein at least one of the vessels has therein a plurality of metallic elements in electrical contact with the vessel and which increase the internal surface area of the vessel from which gases are evolved in use.

7. Apparatus as claimed in any preceding claim, wherein each vessel is in the form of a tube which protrudes from the electrolyte in the casing with a part thereof immersed in the electrolyte in the casing, the ends of the tubes which are in the electrolyte being closed.

8. Apparatus as claimed in claim 7, wherein the casing is closed by a cap having an opening through which replenishment electrolyte can be fed into the casing.

9. Apparatus as claimed in claim 1 and comprising first and second upright tubes constituting said vessels, the tubes being closed at their lower ends and open at their upper ends, a lower part of each tube being immersed in the electrolyte in the casing and an upper part of each tube protruding upwardly from the electrolyte in the casing.

10. Apparatus as claimed in claim 9, wherein each tube is surrounded by a grid of acid resistant material with perforated electrically conductive metal elements sheathing the grids, each tube being coated with an electrochemically active material which is on the outside of the metal element, in the perforations of the metal element, in the interstices of the grid and in contact with the tube.

1 1 . Apparatus as claimed in claim 10, wherein said tubes are oval in cross section, said grids and said metal elements being in the form of sleeves of the same shape.

12. Apparatus as claimed in claim 10 or 1 1 and including a separator, which is permeable to the electrolyte in the casing, sheathing each metal element, grid and tube.

13. Apparatus as claimed in any one of claims 10 to 12, and including tabs protruding from the tubes and the metal elements for connecting the metal elements and the tubes into external electrical circuits.

14. Apparatus as claimed in any preceding claim in which each vessel is of lead which is coated internally with a metal that is more electrically conductive than lead.

15. Apparatus as claimed in any one of claims 1 to 13, wherein each vessel is of a metal that is more electrically conductive than lead, and has a lead coating to protect it from the electrolyte.

16. Apparatus as claimed in any preceding claim and including means for agitating the electrolyte in the casing.

17. Apparatus as claimed in any preceding claim, wherein the electrolyte in the casing is acidic and the electrolyte in the vessels is alkaline.

18. A method of generating hydrogen and storing electrical power which comprises apply a voltage across the vessels of the apparatus claimed in claim 2 derived from a renewable source of electrical power, and supplying power to said vessels from the battery constituted by the pasted electrodes upon the power available from the renewable source falling below a predetermined value.

19. Electrolysis apparatus as claimed in claim 2, with the modification that one of said vessels is replaced by a plate electrode which is coated with chemically active material of the opposite polarity to that coated on the outside of the remaining vessel.

Description:
PRODUCTION OF HYDROGEN AND OXYGEN BY ELECTROLYSIS

FIELD OF THE INVENTION This invention relates to the production of hydrogen and oxygen by electrolysis.

BACKGROUND TO THE INVENTION

A conventional electrolysis cell comprises a casing filled with electrolyte, spaced apart electrodes in the electrolyte and a membrane which is permeable to the electrolyte between the electrodes. When the electrodes are connected across a source of direct current there is a current flow through the electrolyte between the anode and the cathode. If the voltage is sufficient, gassing occurs and hydrogen is produced at the cathode and oxygen at the anode. The anode and cathode reactions can be written as follows:

Anode 2H2O - 02+4H + +4e

Cathode 4H + + 4e - 2H2 The reaction at the anode produces oxygen and positively charged hydrogen ions. The electrons flow through the external circuit and the hydrogen ions pass through the membrane to the cathode. Here the positively charged hydrogen ions combine with the negative electrons from the external circuit to form hydrogen gas. An object of the present invention is to provide an improved electrolysis cell.

Another object of the present invention is to provide an electrode for use in a combined electrical storage battery and electrolysis cell. A further object of the present invention is to provide a combined electrolysis cell and electrical storage battery.

BRIEF DESCRIPTION OF THE INVENTION

According to the present invention there is provided electrolysis apparatus comprising a casing containing electrolyte, first and second spaced apart vessels each of which is of electrically conductive metal and has its outer surface in contact with the electrolyte in the casing, said vessels having electrolyte in them which gases at a lower voltage than the electrolyte in the casing, and outlets from said vessels for gases that are evolved when, in use, current flows through the apparatus.

According to a further aspect of the present invention there is provided electrolysis apparatus comprising a casing containing electrolyte, first and second spaced apart vessels each of which is of electrically conductive metal and has its outer surface in contact with the electrolyte in the casing, said vessels having electrolyte in them which gases at a lower voltage than the electrolyte in the casing, there being outlets from said vessels for gases that are evolved when, in use, current flows through the apparatus, one of said vessels being coated externally with electrochemically active negative material and the other being coated externally with electrochemically active positive material.

The apparatus defined in the preceding paragraph can be modified by replacing one of the vessels by a plate electrode which is coated with electrochemically active material of the opposite polarity to that with which the outside of the remaining vessel is coated.

There can be a grid of electrolyte resistant material externally of each vessel and a metal element with perforations in it adjacent said grid, the paste being on the outside of the metal element, in the perforations of the metal element in the interstices of the grid and in contact with the vessel.

An electrolyte permeable separator can be provided between said vessels to prevent direct contact between them.

Preferably each vessel has a first part in contact with the electrolyte in the casing and a second part which protrudes from the electrolyte in the casing. At least one of the vessels can have therein a plurality of metallic elements in electrical contact with the vessel, this being to increase the internal surface area of the vessel from which gases are evolved in use.

In one form of the apparatus each vessel comprises a tube which protrudes from the electrolyte in the casing with a part thereof immersed in the electrolyte in the casing, the ends of the tubes which are in the electrolyte being closed. The casing can be closed by a cap having an opening through which replenishment electrolyte can be fed into the casing. In the preferred form the electrolysis apparatus according to the invention comprises first and second upright tubes constituting said vessels, the tubes being closed at their lower ends and open at their upper ends, a lower part of each tube being immersed in the electrolyte in the casing and an upper part of each tube protruding upwardly from the electrolyte in the casing.

In this preferred form each tube can be surrounded by a grid of acid resistant material with perforated electrically conductive metal elements sheathing the grids, each tube being coated with an electrochemically active material which is on the outside of the metal element, in the perforations of the metal element, in the interstices of the grid and in contact with the tube.

Said tubes are preferably oval in cross section, said grids and said metal elements being in the form of sleeves of the same shape. There can be separators, which are permeable to the electrolyte in the casing, sheathing each metal element, grid and tube.

For connecting the metal elements and the tubes into external electrical circuits there can be tabs protruding from the tubes and the metal elements.

Each vessel can be of lead which is coated internally with a metal that is more electrically conductive than lead. Alternatively each vessel can be of a metal that is more electrically conductive than lead, and which has a lead coating to protect it from the electrolyte. The electrolyte in the casing can be acidic and the electrolyte in the vessels can be alkaline.

Means can be provided for agitating the electrolyte in the casing.

According to another aspect of the present invention there is provided a method of generating hydrogen and storing electrical power which comprises applying a voltage across the vessels of the apparatus which voltage is derived from a renewable source of electrical power, and supplying power to said vessels from the battery constituted by the pasted electrodes upon the power available from the renewable source falling below a predetermined value.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:-

Figure 1 is an isometric view of the components of a combined battery and electrolysis electrode in accordance with the present invention;

Figure 2 is a vertical section through an assembled electrode comprising the components illustrated in Figure 1 together with some metallic balls;

Figure 3 is a view similar to that of Figure 2 but illustrating two electrodes;

Figure 4 is a diagrammatic view of a part assembled electrolysis cell;

Figure 5 is a diagrammatic view of the assembled electrolysis cell; and Figure 6 is diagrammatic view of a further form of electrode.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates the three components of a combined battery and electrolysis electrode. The first of these components is a lead tube 10 which is internally coated with a metal that is more electrically conductive than lead. Nickel is the preferred coating metal. The tube 10 is closed at its lower end by a base 12 (see Figure 2) and open at its upper end. A tab 14 secured to the metal coating on the inside surface of the tube 10 serves as a terminal by means of which the tube 10 can be connected into an external circuit. The second component is a cylindrical sleeve 16 constituted by a mesh of an electrically insulating material such as synthetic plastics. The third component is an electrically conductive cylindrical metal sheath 18 which has a multitude of perforations 20 in it apart from over its upper section. The tube 10 is longer than both the sleeve 16 and the sheath 18, and the sleeve 16 and the sheath 18 are of the same length. A tab 22 secured to the upper section of the sheath 18 serves as a terminal permitting the sheath 18 to be connected to an external circuit.

In the form of the invention which comprises cylindrical lead tubes, the sleeve 16 and sheath 18 are both cylindrical sleeves.

The electrode, designated 24 in Figure 2, is assembled by sliding the tube 10 into the sleeve 16 and then sliding the nested tube 10 and sleeve 16 into the sheath 18. The upper part of the tube 10 protrudes from the sleeve 16 and sheath 18. The unperforated upper part of the sheath 18 protrudes above the upper edge of the sleeve

16. The sleeve 16 prevents direct electrical contact between the tube 10 and the sheath 18. The sleeve 16 is the same length as the perforated part of the sheath 18.

The entire length of the sheath 18, apart from the unperforated upper part, is then pasted with electrochemically active material designated 26 in Figure 2. The material

26 is on the outside of the sheath 18, passes through the perforations in the sheath 18, through the openings in the mesh constituting the sleeve 16 and into contact with the outer surface of the tube 10. The perforations in the sheath 18 and the openings in the mesh enable a sufficient volume of electrochemically active material to be provided.

It is possible to omit the sleeve 16 so that the sheaths 18 are in direct contact with the tubes 10. This, however, reduces the volume of electrochemically active material that can be pasted onto the tube 10. To form an electrical storage cell a first electrode 24.1 (Figure 3) is pasted with electrochemically active positive material designated 28 and a second electrode 24.2 is pasted with electrochemically active negative material designated 30. Both electrodes 24.1 and 24.2 are shown in Figure 3. The electrodes 24.1 and 24.2 are both wrapped in a separator material which is permeable to the electrolyte. The separators are between the tubes. In Figure 4 a small part of a separator is shown at 32. The separators are in the form of cylinders which entirely surround the sheaths 18. The electrodes 24.1 and 24.2 are shown inserted into a cylindrical casing 34 which is filled with acidic electrolyte which is preferably sulphuric acid. The separators prevent direct contact between the electrodes 24.1 and 24.2.

The tubes 10 constitute vessels for containing an alkaline electrolyte. Suitable electrolytes are potassium hydroxide and sodium hydroxide.

The separators 32 cover the pasted parts of the sheaths 18. The unpasted upper parts of the sheaths 18 protrude from the separators. Turning now to Figure 5, this shows the electrodes 24.1 and 24.2 standing juxtaposed to one another and upright in the cylindrical casing 34 which is closed by a cover 36 with holes in it through which the upper parts of the electrodes 24.1 and 24.2 protrude so that the tabs 14 and 22 are accessible. The lower parts of the electrodes are in contact with the electrolyte in the casing 34.

Openings 38 in the cover 36 permit acidic electrolyte which is lost during operation to be replaced.

The effective internal surface areas of the tubes 10 can be increased by filling them with metallic balls, or balls of electrically non-conductive material which are coated with an electrically conductive metal such as nickel and which are in electrical contact with the tubes. Such balls are shown at 40 in Figure 2. It is possible for the balls to be replaced by elements of any shape which are either electrically conductive or coated with nickel or other electrically conductive metal. It is possible for only the tube in which hydrogen is evolved to have the metal elements in it.

Caps, not shown, with pipes (not shown) extending from them are fitted to the tubes 10. These constitute outlets through which evolved gases are conveyed away. Inlets are provided which enable replenishment alkaline electrolyte to be added.

To produce hydrogen, a direct current charging source is connected across the terminal tabs 14 of the tubes 10. The source can be rectified alternating current taken from the grid but it is preferably derived from solar panels and / or wind driven generators.

The voltage that has to be applied to cause the acid electrolyte to gas is 2.3 volts. The alkaline electrolyte in the tubes 10 gases when 1 .75 volts or above is applied. Experimental work has shown that if a voltage between these two figures is applied, say 2.25 volts, the alkaline electrolyte gases but the acid electrolyte does not. Hydrogen is evolved from the inside surface of that one of the tubes 10 which is connected to the negative side of the charging source and acts as the cathode. Hydrogen is also evolved from the surfaces of the elements such as balls which are in that tube. Oxygen is evolved on the inside surface of the tube 10 which is connected to the positive side of the power source and which acts as the cathode.

It will be understood from this that the electrolyte chosen, and the voltage applied, are selected so that gassing takes place in the tubes 10 but not externally of the tubes 10.

Electron flow between the cathode and the anode in a conventional electrolysis plant is through the electrolyte and a permeable membrane located in the space between the anode and the cathode.

In the construction according to the invention electron flow is from one lead tube 10 to the other lead tube 10 through the electrolyte and through the coating which is on the outside of each tube 10, in the perforations of the sheath and the interstices of the mesh sleeve 16. Consequently, simultaneously with generating hydrogen and oxygen, the battery cell constituted by the two electrodes 24.1 and 24.2 is charged. As there is no gassing in the electrolyte in the casing 34 means are provided to agitate the electrolyte and prevent stratification. Such means can be a pipe for bubbling air through the electrolyte or a mechanical stirrer.

Whilst the electrodes are shown as being circular in horizontal cross-section they could be rectangular, including square, oval or any other shape which permits them to be packed in an outer casing without wasting space but while still leaving sufficient free space in which an adequate supply of acidic electrolyte can be contained. Oval tubes have the advantage of providing more surface area. Whilst the tubes 10 can be of lead it is possible to use a tube of a more conductive metal such as aluminium which is coated internally and externally with a protective layer of lead or nickel.

The electrode of Figure 6 has many features in common with the electrodes of Figures 1 to 3 and where applicable like references have been used.

A terminal in the form of a solid rod 42 is co-axial with the tube 10. The rod 42 extends the full length of the tube and protrudes from the open end of the tube. The cylindrical space between the rod 42 and the inner face of the tube 10 is filled with balls 40 or other electrically conductive elements.

The storage capacity and generation capacity can be increased by placing multiple tubes 10 in an outer casing. The electrical storage part of the apparatus described above is constituted by a lead acid battery. It is, however, possible to use other forms of battery such as nickel metal hydride and lithium ion. Whilst it is preferred that the apparatus include two vessels containing electrolyte, it is possible to replace one of the vessels by a plate electrode which is coated with electrochemically active material of opposite polarity to that with which the remaining vessel is coated. Preferably the remaining vessel is the one in which hydrogen is evolved.