FR3097217A1 - Device for hyper concentration and transport of remote solar energy by optical fiber associated with a process for producing an h2 / o2 mixture by thermophotolysis - Google Patents

Abstract

Device for producing a hydrogen / oxygen pair from a solar energy concentrator comprising a means for collecting solar energy consisting of one or more optical fibers characterized in that the input and output of the or hollow optical fibers is formed by an unstretched zone of the preform allowing the remote transport of the solar flux.

Description

Device for hyperconcentration and transport of remote solar energy by optical fiber associated with a process for producing an h2/o2 mixture by thermophotolysis

Field of invention

The present invention relates to the production of solar energy at very low cost (equivalent or lower than the price of crude oil) with a "free" process (solar energy source) replacing oil / fossil fuels and conventional batteries (storage) .

The advantages are the avoidance of complex or expensive materials (rare metals, catalysts, etc.), the absence of wear or maintenance as in electrolysers or fuel cells, abundant and available materials (carbon/graphite, water, …) free sources of energy (sun, water), to provide 100% clean renewable energy with no societal or environmental impact, with a lifespan of at least 40 years. It presents the possibility of supplying fuel cells as well as carrying out storage, in particular by burning the h2/o2 mixture, which are stored separately and then burnt (exothermic reaction) in a specific burner to supply a thermodynamic device or a furnace, the combustion producing water vapor which is recycled indefinitely in the invention

Principle of operation:

The invention is based on the principle of solar hyper concentration (of the order of 10,000 suns) and the injection of the concentrated solar flux into a preform, whether or not equipped with windows leading into a fiber (or fiber bundle) ideally hollow optics whose core is empty (pure waveguide without optical losses), whose inlet is a preform of sufficient diameter to receive the concentrated flux without damage. The preform may be full (bar/stretched tube) or closed by an entry window and the opposite end is similarly closed so that the interior of the fiber is under vacuum, the vacuum not opposing not to the conduction of light that over a broad spectrum.

The waveguide assembly consists of glasses of different indexes constituting the waveguide by reflection = two coaxial glass tubes with different optical properties then stretched to form the fiber, the core being ideally under vacuum.

A gas trap (in English “getter”) or an appropriate device accessing the core under vacuum makes it possible to absorb/evacuate any contaminants/degassing. A 100µm industrial laser optical fiber can transport 100kw, a 1,000µ hollow fiber would reach and exceed 1.6MW. (see in particular the article “Microstructured optical fibers” by Laurent Provino, Laurent Brilland, Achille Monteville, David Landais, Olivier Le Goffic, Denis Tregoat and David Mechin).

The end of the fiber inside the reactor ends with a second smaller preform which can be solid or equipped with a window, collimating optics, condenser, focusing optics, etc. in glass or materials with suitable optical properties forming the appropriate optical structure to allow focusing at a point, taking into account the different wavelengths in particular by the use for example of optical doublets. The optics receive one (or more) anti-reflection treatment and possibly a cooling device or temperature control. The optical fiber is ideally of very short length for a low power installation, the reactor being installed on the solar concentrator. During very high power, the reactor can be remote from the sources of solar concentration that can contain one or more remote concentrators, so as to have a system that perfectly optimizes the parameters. = remote transport by optical fiber of highly concentrated solar energy capable of transporting 1MW optical and more (1,000µ).

The end of the fiber or fiber bundles then arrives in the "reactor" (dissociator would be fairer), which consists of a vacuum cavity ideally made of graphite or suitable materials preferably covered with a hard surface. At one end is the nozzle(s) projecting the flow of water (or steam), which is intercepted by the solar flow and dissociated. Nozzle and fibre(s) can be coaxial or at a greater or lesser angle to avoid any deterioration or contamination of the optical end/optical components or thermal shock. The optical components are covered with a protection against chemical attack from the water molecule or h2 and o2 compounds. A large set of fibers can also be nearly perpendicular to the nozzle(s). The reactor opens to allow easy replacement of damaged components.

The reactor being subjected to a high temperature due to inevitable losses, this heat source can be used to produce steam at high temperature by a device, for example tubular, surrounding the vacuum enclosure while ensuring its cooling. This high temperature and high pressure water vapor arrives in the vacuum chamber and is immediately dissociated by the luminous flux. The advantage of steam being that it carries part of the energy necessary for dissociation.

To increase the overall effective yield, the presence of additional sources can be envisaged sending a concentrated flow to the water/steam flow in wavelengths favorable to dissociation, such as certain electromagnetic radiation (microwaves, etc.) light from LEDs or laser diodes I, visible, UV, X, etc… as well as a mixture of these waves.

The water/light flows are regulated to perfectly optimize the dissociation and avoid any deterioration of the components or other harmful phenomena. Sensors arranged in different places are provided in this sense, they also serve as security

The vacuum within the reactor makes it possible to carry out a chemical quenching avoiding molecular recombination or explosion in the reactor, and then to suck the o2/h2 atoms towards the final separation device (purification) as well as to recycle the water/steam not having been dissociated and to avoid pollution detrimental to the purity of the gases.

Starting from the reactor, the atoms are drawn into a vortex which can be of the Ranque-Hilsch type, facilitating separation due to the different atomic masses (coef 1 to 16) whose walls forming an exchanger allow cooling while preheating the water to be separated . The vortex then separates into two distinct circuits, one preferentially containing oxygen and the second hydrogen.

A pre-filtration device makes it possible to return the water that has not been dissociated and to reinject it into the reactor.

Then comes an additional separation process using an electrostatic and electromagnetic field or coupling of a set of devices and any other suitable process allowing excellent molecular separation and returning the atoms to the correct circuit. The final purification can be carried out by means such as chemical filtration processes, molecular sieves or others, the objective being the supply of high purity gases which can in particular be recycled indefinitely within the same installation in a closed circuit in the particularly in the context of solar fuel or heat pump “batteries” or any other device.

The optical components, in particular in silica, are ideally covered with a protective layer to protect them from possible chemical reactions with O2/H2 or H2O which could degrade their properties.

Field of invention

The present invention relates to the field of the production of ENR (New Renewable Energy) of solar origin in the form of the hydrogen/oxygen couple being called "solar fuel" (trade name), from a solar power plant associated with a fiber special optics performing solar hyper-concentration within a “reactor” used here to dissociate the water molecule with very high efficiency and without wear or maintenance or the use of chemicals.

This hydrogen/oxygen couple with an energy density of 33kwh/kg (Li/ion batteries = 200 wh/kg) makes it possible, for example, to power different types of processes such as very high density energy storage (solar fuel) , power to heat pumps (fuel cells), engines or any combustion devices (ovens, flames, heaters, DHW, cooking equipment, etc.) traditionally running on hydrocarbons, or even rocket engines and all spacecraft.

The invention ideally implements a solar concentrator allowing a concentration rate of up to 20,000 suns at the focal point called a hyper concentrator. It is therefore possible to use an optical fiber, ideally hollow, to achieve a concentration rate of around 30,000 suns and transport the solar flux remotely to a target or inject it into a reactor.

This energy density is therefore sufficient to ensure the spontaneous and complete dissociation of the water molecule simply by a light/matter interaction in this process which we will call thermophotolysis since it is the combined action of several bands of the spectrum visible and invisible optics on a stream of water. The term "Thermo" from temperature/thermal agitation from infrared rays, the term "photo" from photons of the visible or higher spectrum (UV,X), and "lyse" for dissociation.

A method of energy transport that has been developed and used more recently in history is the use of optical guides.

Probably the best known type of optical guide is fiber optics. The latter can be made of silica, glass or polymer. It is generally made of a core of refractive index n _c and of a sheath having a refractive index n _g less than that of the core. The radiation it carries propagates in the heart by total internal reflection.

According to another aspect of the invention, the optical fiber can advantageously be of the hollow-core type, in which case the transmitted light power is not subject to the purity of the materials used and can therefore transport very high powers.

According to another aspect of the invention, the energy converter uses the principle of the dissociation of the water molecule into hydrogen and oxygen under the effect of high intensity light energy.

State of the art

We know in the state of the art the American patent US 4201197 describing a parabolic mirror concentrator collecting radiant solar energy and reflecting it in a small mirror placed on the direction of the large mirror. A fiber optic cable has one end positioned within an opening in the top of the large mirror, and light energy is directed to the fiber ends in the fiber optic cable. To avoid the formation of destructive hot spots by the focusing of rays inclined with respect to the direction of the fibers, the fibers close to the end receiving the radiant energy are collected in groups and an opaque and reflective coating surrounds each of the groups.

International patent application WO 2015036809 describes another prior art solution for harvesting solar energy by polymerized optical fibers or glass fibers entwined in a helical manner with strips or patches of organic solar cells to recover the electrical energy from solar light concentrators from diffraction at the perimeter of the light guide.

Concerning the second aspect of the invention, the French patent FR2902416 is known in the state of the art describing a reactor with controlled thermal gradient for the production of pure hydrogen. This patent relates to a holistic approach to the thermal dissociation of water and the separation of hydrogen, where a temperature profile is achieved by the choice of a specific geometry, by the dimensioning of the device, and by the positioning of its components. The heat source or sources are placed in water inside a reaction chamber, with sufficient power to heat the water in their vicinity to temperatures where it dissociates. The walls of the reaction chamber are cooled. Oxygen-selective membranes are placed near heat sources. They are used to extract oxygen and they serve as a screen to protect other components from direct thermal radiation coming from heat sources. Hydrogen-selective membranes are placed in cooler areas near the walls of the reaction chamber.

European patent EP1019316 describes another solution for producing hydrogen by thermal decomposition of water.

This prior art process consists in heating water to a dissociation temperature so as to obtain a dissociated reaction mixture comprising hydrogen and oxygen in the gaseous state. A vortex is created in the reaction mixture in order to subject this mixture to a centrifugal force on the internal longitudinal axis of a vortex tube reactor so that a radial stratification of the hydrogen and oxygen gases in the internal space of said tube. Hydrogen and oxygen should preferably be extracted from the reaction mixture at points spaced along the internal space of the vortex tube reactor.

Disadvantages of the prior art

The solutions of the prior art concerning the production of hydrogen and oxygen by electrolysis or PAC (fuel cells) are characterized by their low efficiency (yields of the order of 50/60%), the use of materials costly (platinum, heavy metals, etc.), chemical products, increased maintenance requiring highly specialized labour, regular exchange of its constituents due to wear/erosion, and a source of electrical energy with very low efficiency (PV 6%, thermal/nuclear power stations 30%) lowering the overall transformation performance to only reach a few % in the end. In addition, known electrical sources have a significant societal and environmental impact.

The solutions of the prior art concerning the production of hydrogen and oxygen by solar means are not satisfactory because they require complex equipment such as heavy parabolic concentrators with heliostatic devices associated with high temperature catalysts using expensive materials. and degrading rapidly and whose yield is particularly low.

The solutions of the prior art concerning the conversion of energy for the production of hydrogen and oxygen are not satisfactory either because they require complex and low-yield equipment whose lifespan is not adapted to industrial processes due to rapid degradation of its constituents.

The solutions of the prior art concerning the production of hydrogen and oxygen by direct solar means are not satisfactory because they require powerful and cumbersome parabolic concentrators which do not make it possible to obtain a sufficient energy density to dissociate the molecule water beyond a yield of 40% and requiring significant cooling of the reactor enclosure as well as the use of rapidly degrading catalysts.

The solutions of the prior art concerning the transport of solar energy by optical fibers are not completely satisfactory because they require a complex treatment of each of the fibers in order to allow an optimal collection of solar energy without degradation of the fiber. . In addition, the amount of energy is far too low to allow real efficiency of the device.

Solution provided by the invention

In order to remedy these drawbacks, the invention first relates to a high-density solar energy concentrator called a hyperconcentrator, comprising a means of collecting solar energy consisting of one (or more) optical fiber characterized in that the input of the optical fiber is constituted by an unstretched zone of the preform and the output end is introduced into an energy conversion module.

According to an advantageous embodiment, said energy conversion module is for example constituted by a reactor which can be made of graphite and whose internal surfaces are hardened to prevent erosion phenomena, which can be opened easily to allow it to be changed components or perform maintenance.

Said reactor is connected to a vacuum means which comprises inside a water micronization nozzle in a zone receiving the transmitted light energy, the graphite reactor having an outlet leading to a vortex to separate the oxygen and hydrogen, which are found in two distinct circuits.

At the end of the vortex, the vacuum means is advantageously divided into two distinct sections, one aspirating hydrogen and the other oxygen so as to avoid their mixing. Said means of placing under vacuum is equipped with a device making it possible to recycle the gases or vapor which have not been completely separated and to reinject them into the reactor.

According to a particular variant, the output end of a solar energy collection optical fiber is engaged in said cavity.

Advantageously, said micronization nozzle is arranged opposite the output end of said optical fiber, coaxially or not.

According to a variant, said reactor comprises a water injector for the misting of a very fine stream or water vapor which will be subjected to a temperature resulting from the interaction with the beam of light energy, causing its spontaneous chemical dissociation into its two elements, H2 and O2.

According to another variant, said reactor having a separator for dissociating mist water or steam by thermophotolysis and producing a jet of molecules of different masses separated by means of a cyclonic vortex-type device generating two distinct flows of hydrogen and oxygen.

Detailed description of a non-limiting example of the invention

The present invention will be better understood on reading the detailed description of a non-limiting example of the invention which follows, with reference to the appended drawings where:

- Figure 1 shows a schematic view of a fiber

- FIG. 2 represents a schematic view of the energy converter.

The invention described with reference to Figures 1 and 2 relates to a device for producing a hydrogen/oxygen couple from a solar energy concentrator comprising a means of collecting solar energy consisting of one or more optical fibers , preferably hollow. The input and the output of the optical fiber(s) (1) is constituted by an unstretched zone (3) of the preform allowing the remote transport of the solar flux.

The ends of the preform (2) of the hollow fiber (1) comprises a window (3) or optical coupling (collimation) plus a gas trap (in English “getter”).

The other end of the fiber (1) also has an exit preform/window (4) with focusing optics (5) towards a focal point (6)

The energy conversion module consists of a reactor (11) defining a volume (11) under vacuum, with a water/steam inlet (12) and a high pressure water/steam inlet (13) supplying a nozzle.

The optical fibers (14) have different possible conformations, coaxial to perpendicular. At outlet (15) h2/o2 opens into a vortex and heat exchanger.

Equipment (16) carries out a residual h2o prefiltration. A separator (17) provides additional electrostatic/electromagnetic separation. The non-dissociated water is reinjected into the circuit.

The module (19) redirects atoms to their final circuit. A filter (20) provides the final filtration/purification and two separate pumping units (h2 and o2) (21) by vacuum pump motors.

The energy conversion module consists of a reactor (11) for example made of graphite having a cavity (11) whose surfaces are hardened to prevent erosion, connected to a vacuum means, said module comprising a nozzle (4 ) for micronizing water inside said cavity (11), in a zone receiving the transmitted light energy, the graphite reactor (11) having an outlet (18) leading to a vortex to separate the oxygen and hydrogen.

The micronization nozzle is arranged opposite the output end of said optical fiber, coaxially or almost perpendicularly.

The reactor (10) comprises a water injector for the misting of a very fine mist of water or steam which will be subjected to a high temperature and action of photons resulting from the interaction with the beam(s) of light energy, causing its spontaneous chemical dissociation into its two elements, H2 and O.

Description of the energy transport between the energy collector and the energy converter

The transport of the solar energy concentrated by the heliostat between the energy collector and the energy converter is carried out by an optical fiber or by a bundle of optical fibers.

The optical fiber has a numerical aperture which allows the injection of all the solar radiation sent by the concentrator. The numerical aperture is preferably greater than 0.42. The optical fiber must also transmit the solar spectrum as efficiently as possible, that is to say with a minimum of absorption. The tolerance of the fiber is at least 500°C, especially when the injected solar radiation is highly concentrated and when the fiber strongly absorbs a certain band of the solar spectrum, creating heating of the guide in its first section.

In addition, the resistance to heat makes it simpler to couple it with the thermal accumulator. Indeed, fewer special measures have to be taken in order to prevent the energy converter from transmitting too much heat to the guide, creating its overheating in its section close to the converter. The flexibility or maneuverability of the guide is also an advantage to be considered in order to make it easier to install on the concentrator matrix. The constraints are often at the level of the minimum radius of curvature of the guide to be respected.

Preferably, the fiber or the bundle of fibers is based on preferably hollow silica because of its transmission of the solar spectrum, which can be excellent, as well as its resistance to heat. Indeed, after integration along the solar spectrum. The absorption of such silica fibers is low, of the order of 0.014dB/m to 0.348dB/m when the transmission is made in the core and the losses are lower when the fiber is hollow.

This amounts to saying that from 92.3% to 99.7% of the solar spectrum injected into a portion of fiber one meter long will be transmitted, without taking into account the losses by reflection at the end of the fiber, these losses being lower when it is a hollow fiber

A limitation is at the level of the maximum focal length that a concentrator can have concerns the diameter of the silica fibers on the market which does not exceed 1.5 mm at the level of the heart. Indeed, the higher the focal length, the larger the focal point. The theoretical magnitude of the focal point given by the sun is 0.01 times the focal length of the concentrator.

Considering a perfect concentrator, if we want to inject all the solar energy collected by it into a 1.5mm silica fiber, the focal length cannot be more than 150mm.

In order to improve this parameter, the transport is provided by one or more fibers formed by drawing, for example, one or more bars or glass cylinders, the primer of which is kept.

The optical fiber is formed by drawing a bar (or cylinders or other shapes) having an initial diameter of, for example, 100 millimeters and a length that can be from a few tens of centimeters to several meters.

The first step consists of assembling the tubes and/or a concentrically mounted cylindrical silica bar. The whole is heated to ensure the homogeneity of the glass bar.

The bar thus obtained will ideally be installed vertically in a tower and heated for example with gas, electric or even solar ramps. The glass will stretch and "flow" down to be wound onto a spool. The thickness of the fiber is measured to control the speed of the winder motor, in order to ensure a constant diameter.

When the desired length is obtained, the stretching zone is kept where the bar is extended by the tapered part (1), and the bar is cut to keep a heel (2) a few millimeters long, which is polished the end according to a transverse section plane (3). A cleavage can also be performed to achieve a clean cut

For an extended collection surface, several fibers thus produced are combined to form a bundle, the collection zone of which is constituted by the juxtaposition of the front ends (3).

Shaping can also be carried out with any other suitable stretching process which may be horizontal (inspired by the device for stretching capillary columns of silica chromatographs), or whose heating/fusion would be carried out by solar means

Description of the energy converter

According to a non-limiting aspect of the invention, the dissociation of water by solar energy is ensured by a principle of thermophotolysis ensuring the decomposition of water, optionally in the presence of a catalyst, under the action of sunlight and possibly additional radiation, with production of H2 and O2, or other molecules such as H2O2, in a reactor ideally formed by a body of graphite (10) whose surfaces are hardened and presenting a cavity (11) under partial void.

This reactor is intended to allow a chemical dissociation of water by the combined action of heat and photons, that is to say a rupture of molecules approaching 100% efficiency at 2,500°C at the point of impact, or at lower temperatures in the presence of a suitable catalyst or radiation. It is therefore an endothermic chemical reaction, giving 2 H2O → 2 H2 + O2, and ΔH° = 286 kJ/mole. The molecular separation could be carried out either by cyclonic vortex, the molecules being ejected at supersonic speed, or by membrane filtration, or thermochemical or any other suitable process, the molecular weight of the atoms being considerably different.

By preparing dihydrogen/oxygen by photodissociation of water by irradiation, in particular by irradiation from solar radiation, it is possible to transform light energy, in particular solar energy, into chemical energy in the form dihydrogen and dioxygen can then be separated and then stored. This chemical energy in the form of stored dihydrogen/dioxygen can then be transported or used later.

The reactor (11) is for example made of graphite or carbon/graphite which is ideally covered with a thin layer such as a carbide to avoid erosion phenomena linked to supersonic flows.

The solar energy coming from the concentrator is transmitted via a fiber (13), in an axial direction

The reactor also has various connections:

1°) A water injector (17) for the misting of a very fine mist of water which will be subjected to a temperature of 2,500°C resulting from the interaction with the beam of light energy, causing its chemical dissociation spontaneous into its two elements, H2 and O.

2°) One or more optical fibers bringing the concentrated solar flux

3°) A separator (17): The water dissociated by thermophotolysis produces a jet of molecules of different masses separated via a cyclonic vortex-type device generating two distinct flows of hydrogen and oxygen.

4°) A return of undissociated water molecules from the separator devices to be reinjected and dissociated.

Hydrogen ions can be separated from oxygen ions using a Ranque-Hilsch vortex and an electrostatic and/or electromagnetic field.

Claims (10)

Device for producing a hydrogen/oxygen couple from a solar energy concentrator comprising a means of collecting solar energy consisting of one or more optical fibers (1), characterized in that the input and the output of the hollow optical fiber(s) is constituted by an unstretched zone (3) of the preform (2) allowing the transport of the solar flux. Device for producing a hydrogen/oxygen couple according to Claim 1, characterized in that it comprises an energy conversion module consisting of a reactor (11), for example made of graphite, having a cavity (11) whose surfaces are hardened to to prevent erosion, connected to a vacuum means, said module comprising a nozzle (4) for micronizing water inside said cavity (11), in a zone receiving the light energy transmitted, the reactor (11) of graphite having an outlet (8) leading to a vortex to separate the oxygen and the hydrogen. Device for producing a hydrogen/oxygen couple according to Claim 2, characterized in that the said micronization nozzle (4) is arranged opposite the outlet end of the said optical fiber (1), coaxially or almost perpendicularly. Device for producing a hydrogen/oxygen couple according to Claim 1, characterized in that it consists of preforms (2) formed at the ends facing a hollow fiber (1) comprising a window or optical coupling (collimation) plus a trap gas. Device for producing a hydrogen/oxygen couple according to Claim 3, characterized in that the said reactor (11) comprises a water injector (17) for misting a very fine mist of water or steam which will be subjected at elevated temperature and photon action resulting from interaction with the beam(s) of light energy, causing its spontaneous chemical dissociation into its two elements, H2 and O. Device for producing a solar hydrogen/oxygen couple according to claim 3, characterized in that the said reactor (11) has a separator for dissociating the mist water by thermophotolysis and producing a jet of molecules of different masses separated by means of a cyclonic vortex type device generating two distinct flows of hydrogen and oxygen. Device for producing a hydrogen/oxygen couple according to Claim 1, characterized in that it consists of a pre-filtration and reinjection into a reactor recycling the residual water and of a separation device of the electrostatic and electromagnetic type. allowing increased separation and filtration of h2/o2 compounds as well as their redirection. Device for producing a hydrogen/oxygen pair according to Claim 1, characterized in that it consists of a reactor receiving one or more optical fibers intended to cause a thermophotolysis reaction, the yield of which is improved by the addition of means additional separation elements producing electromagnetic radiation improving the final yield. (LED/laser/x diodes). Device for producing a hydrogen/oxygen pair according to claim 1, characterized in that it has a vacuum means producing suction as well as molecular quenching (sudden cooling) avoiding the recombination or explosion of a gas mixture of the h2/o2 type. Device for producing a hydrogen/oxygen pair according to claim 1, characterized in that it comprises preforms, fibers and optical components are covered with a protective layer against chemical attack by water and h2/o2 compounds.