The present invention relates to a high-pressure electrolysis device for generating hydrogen and oxygen.

The currently available electrolyzers are low pressure or high pressure electro lyzers up to about 350 bar, usually based upon membrane technology. Most electrolyzers have a stacked design, i.e. sets of prefabricated parts are stacked to assemble the electrolyzer. Due to the nature of stacked designs the pressure which can be applied is limited.

WO 2011/012507 A1 discloses a method and device for generating hydrogen and oxygen, the device comprising a high-pressure electrolysis unit from which the generated gases are conveyed into pressure containers, wherein the high-pressure unit comprises a fully enclosed polymer electrolyte membrane (PEM) high-pressure electrolysis.

JP 2012-057220 A discloses a device for generating hydrogen and oxygen comprising an electrolysis unit for converting electrical energy into energy in the form of gas, wherein the electrolysis unit is a high-pressure electrolysis unit which comprises a massive bloc of insulating material, for example ceramic or polymeric material.

EP 0 297 880 A1 discloses a solid oxide water electrolyzer having a multiplicity of electrically interconnected vertical tubes sealed at one end where each tube comprises a solid oxide oxygen ion conducting electrolyte sandwiched between an oxygen permeable anode on the inside of the tube and an oxygen permeable cathode on the outside of the tube, a first plenum leakably sealed to the outside of the tubes into which steam can be admitted, a second plenum leakably sealed to the outside of the tubes in gaseous communication with the inside of the tubes from which oxygen can be taken, and a third plenum inbetween the first plenum and the second plenum into which pressurized steam can be admitted.

WO 2004/076721 A2 discloses an electrolyzer cell for the electrolysis of water which comprises a cathode of generally tubular configuration within which is disposed an anode separated from the cathode by a separation membrane of generally tubular configuration which divides the electrolyte chamber into an anode sub-chamber and a cathode sub-chamber. An electrolyzer apparatus includes an array of individual cells across each of which an electric potential is imposed by a DC generator via electric leads. Hydrogen gas generated within cells from electrolyte is removed via hydrogen gas take-off lines and hydrogen manifold line. By-product oxygen is removed from cells by oxygen gas take-off lines and oxygen manifold line. US 2010/0276299 A1 discloses a method or apparatus for improving the electrolysis efficiency of high-pressure electrolysis cells by decreasing the current density at the anode and reducing an overvoltage at the anode while decreasing the amount of hydrogen permeation through the cell membrane from the cathode chamber to the anode chamber as the high-pressure electrolysis cell is operated.

It is well-known in the art that a major disadvantage of PEM electrolysis cells is that they require an expensive catalyst and that the catalyst layers in the electrolysis cells degrade faster at varying load requirements than in the alkali electrolysis.

Therefore, there is still a need for efficient and cost-effective high-pressure electrolyzers which are not based on PEM technology and in which the problems known in the art relating to high-pressure electrolysis are solved or at least reduced.

The object of the present invention is to provide such a device.

In accordance with the invention a device is provided suitable for generating hydrogen and oxygen, comprising an electrolysis unit for converting electrical energy into energy in the form of gas, wherein the electrolysis unit is a high-pressure alkaline electrolysis unit from which the generated gases are conveyed into pressure containers, wherein the high- pressure electrolysis unit comprises an assembly of tubes and pipes with a plurality of arrays of substantially vertical tubes, wherein each array is interconnected at the lower ends of said vertical tubes by substantially horizontal arrays of pipes, wherein said horizontal pipes are closed at their ends, with the proviso that at least one of said horizontal pipes has a water inlet, wherein said array of horizontal pipes is interconnected by one or more pipes which are positioned perpendicular to said horizontal pipes, wherein said assembly further comprises one or more openings for connections to the electrodes at the upper ends of said vertical tubes being closed and interconnected by a substantially horizontal array of pipes, wherein said horizontal pipes are closed at their outer ends, with the proviso that one level of pipes in said horizontal array of pipes has at least one outlet for hydrogen and another level of pipes in said horizontal array of pipes has at least one outlet for oxygen.

The high-pressure electrolysis device according to the invention thus comprises no stacked design, but an assembly of tubes and pipes of high-pressure and temperature- resistant conductive material. The assembly is used as the containment for the high pressure electrolysis process. High operating pressures are possible and no compression is needed to store and distribute product gas, resulting in an increased total efficiency up to 20% of the total electrolysis process, as no compression of the product gas is needed.

The high-pressure electrolysis unit comprises an assembly of tubes and pipes of temperature-resistant conductive material. The tubes and pipes are closed at their open ends by welding or threaded fitting plugs, with the exception of at least one water inlet connection, at least one hydrogen outlet connection and at least one oxygen outlet connection.

The top part of the internal face of the tube and pipe arrangement is coated with an electrically isolating coating.

Although the words tubes and pipes are frequently used interchangeably, there are significant differences between pipe and tube. As used herein, a ’’pipe” is meant to indicate predominantly a round tubular to distribute fluids and gases, designated by a nominal pipe size (NPS or DN) that represents a rough indication of the pipe conveyance capacity. As used herein, a ’’tube” is meant to indicate predominantly a round, rectangular, squared or oval hollow section measured by outside diameter (OD) and wall thickness (WT), expressed in inches or millimeters. See also hitp://vwAv.werroac.om/Pipes/pipe vs tube.html the contents of which are incorporated herein by reference.

The uncoated internal face of the body is used as the anode or cathode, the electrodes positioned in the vertical tubes are used as the counter electrodes, as cathode or anode, respectively. The counter electrodes are positioned in the vertical tubes. The counter electrodes are supported by and connected with electrode support bars installed in horizontal pipes at the upper end of the array of tubes. The support bars are connected with an external power supply through openings at the outer ends of said horizontal pipes. The openings are then suitably sealed to resist the high-pressure within the unit.

The vertically positioned counter electrodes are surrounded by a top supported cylindrical membrane. The membrane keeps separate the oxygen and hydrogen gases in combination with good electrical conductivity.

The cylindrical membrane can be made in various ways which are known to a person skilled in the art, for example from a fabric.

According to various embodiments, the application of the known electrolysis is realized in the high-pressure circuit, i.e. specifically the water circuit, the electrolysis unit and the gas separation unit are realized in such a way that the equipment units are designed as pressure containers. Consequently, the operating pressure of the electrolysis assembly may range from ambient up to very high pressure. Preferably, the operating pressure ranges from 350 to above 1000 bar to comply with its application.

No compression stage is needed. The entering feedwater is pressurized to the required pressure, resulting in the efficient availability of high pressure product gases.

The high-pressure electrolysis unit performs electrolysis of water by applying a voltage at the electrodes, thereby delivering gaseous oxygen at one side and gaseous hydrogen at the other side. The operating temperature ranges from ambient temperature up to high temperature which is required to enhance the efficiency of the electrolysis. Preferably, the temperature ranges from ambient temperature up to 300°C.

Further details and advantages of the present invention are derived from the following description and explanation of the figures, which relate to exemplary embodiments.

Fig. 1 shows a front side cross-sectional view of a high-pressure electrolysis unit according to the invention.

Fig. 2 shows a left side cross-sectional view of the electrolysis unit of Fig. 1.

The high-pressure electrolysis unit comprises an assembly of interconnected horizontal and vertical metal tubes (1). A water inlet is provided at the lower end of the assembly and two outlets are provided at the top of the assembly for exiting the produced gases hydrogen and oxygen, respectively. The assembly of tubes and pipes is connected to an electrode, in this figure an anode (+), In the vertical tubes the counter electrodes (2) are contained, in this figure defined as cathodes (-). A cylindrical membrane (3) positioned concentrically around the electrode is supported by a membrane support ring (4), which is rigidly fitted in the vertical tubes.

The electrodes are arranged in the vertical tubes and are supported by electrode support bars or profiles (6). Electrically isolating support rings (7) are provided to isolate and support the electrode support bars or profiles (6). Product gas flows through the rings. Welded or threaded fitting plugs (5) are mounted to close the openings of the tubes. Pressure-tight isolated electrical conductors (8) are provided to conduct electrical power supply from the outside of the device to the inside of the device.

Electrode support bars or profiles (6) are installed to support the counter electrodes (2) as well as to conduct the electricity from the pressure-tight isolated electrical conductors (8) to the counter electrodes (2).

From the foregoing description, a person skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications to adapt it to various usages and conditions.