Co-generative device for the production of hydrogen, electric power, and thermal power with zero emissions

Abstract

A system is described for the production of hydrogen and thermal power through a spontaneous electrochemical oxidation-reduction reaction, formed by at least one reactor (1) composed by a loading line (2) that introduces a reacting material into a reaction basin (6); at least one discharge body (12) for the hydroxide produced during the reaction, wherein the pH is transformed into a desired value by the introduction of an acidic solution through a loading line (13); at least one loading line (3) of water that is supplied into the reaction basin (6); at least one cathode body (5) made of porous material containing gaseous oxygen; at least one loading line (4) that allows the oxygen to be replenished at the cathode body (5); at least one porous material filter (7) for separating the gaseous hydrogen from solid residues produced during the reaction; and at least one discharge line (8) for the release of gaseous hydrogen. The system is configured to perform a process for the production of hydrogen and thermal power through an oxidation-reduction reaction between a material acting as an anode, a material acting as a cathode and a material acting as an electrolyte.

Description

[0001] Co-generative device for the production of hydrogen, electric power, and thermal power with zero emissions

[0002] Field of application of the invention

[0003] The present invention pertains to the realization of an integrated system of a reactor wherein an oxidation-reduction reaction occurs between a metal, preferably aluminium, and oxygen in an aqueous environment, capable of producing gaseous hydrogen and heat, and an integrated device designed to recover the thermal power generated by the reaction, in accordance with the preamble of the respective independent claims. The resulting system is intended for use in all the sectors requiring a replacement of fossil fuel -based energy sources with zero-emission energy. Aluminium can play a pivotal role in the energy transition due to its availability and high energy density.

[0004] Prior art

[0005] It is known in the art that, under certain conditions, some metals such as zinc, aluminium, silicon, and others react with water to form their respective hydroxides and generate pure hydrogen gas from water through a phenomenon called hydrolysis. Numerous patents and publications address this principle in various ways, but they all share two main issues: the high cost of catalysts made of rare earths or aluminium alloys with these elements, or the pulverization of aluminium to prevent passivation during the reaction, which hinders the completion of the very reaction. Handling powdered aluminium is highly dangerous due to its pyrophoric nature. In the past, various hydrogen generators have been developed. The following patent documents constitute a comprehensive inventory of devices and methods in the state of the art for generating gaseous hydrogen using the reaction of aluminium or aluminium alloys with water.

[0006] US 909,536 issued to G. F. Brindley et al.: This patent claims the various compositions of the reacting metal for hydrogen generation. The compositions include any powdered metal in tablet form that can form a hydroxide when in contact with a suitable hydroxide solution. Specifically, aluminium is reacted with high concentrations of sodium hydroxide in an aqueous solution to release hydrogen and produce sodium aluminate.

[0007] US 2,721,789, issued on October 25, 1955, to Q.C. Gill: This document discloses the structure of a hydrogen generator for reacting water with a dry charge of aluminium particles and sodium hydroxide flakes. The reaction releases hydrogen gas and produces sodium aluminate.

[0008] US 3,957,483, dated May 18, 1976, to M. Suzuki: This patent claims magnesium plates onto which powdered elements such as iron, zinc, chromium, aluminium, and manganese are deposited, which elements always in contact with an aqueous sodium hydroxide solution, form hydrogen.

[0009] US 3,975,913, issued on August 24, 1976, to D.C. Erickson: This document discloses a hydrogen generator wherein molten aluminium is allowed to react with water. The generator is maintained at a high temperature to keep the metal in a molten state.

[0010] US 4,730,601, issued on March 15, 1988, to H.D. Hubele et al.: The device is provided with a reaction basin for reacting a reactive fuel composition with water. The said fuel composition consists of magnesium and aluminium in a 1 :2 molar ratio, and a second part consists of lithium hydride, magnesium, and aluminium in equal molar ratio.

[0011] US 4,752,463, issued on June 21, 1988, to K. Nagira et al.: This document discloses an alloy that reacts with water to produce gaseous hydrogen. The alloy material is primarily composed of aluminium and 5% to 50% tin.

[0012] US 5,143,047, issued on September 1, 1992, to W.W. Lee: This document describes an apparatus and method for generating steam and gaseous hydrogen. In this apparatus, aluminium powder or an aluminium alloy is allowed to react with water to generate gaseous hydrogen. An electrical energy source is used to initiate the reaction. The electrical energy source is used to cause the explosion of an aluminium conductor and to disperse molten aluminium pieces into a mixture of water and aluminium powder. A heat exchanger is provided to extract useful heat.

[0013] US 2021 / 0276865 Al, filed by Laureen Meroueh from the Massachusetts Institute of Technology: This patent application claims the use of a specially prepared alloy with 50% aluminium and smaller proportions of gallium, bismuth, indium, and other elements in a reactor for hydrogen production from water at ambient temperature and pressure. Gallium and the other elements act as catalysts because although they are part of the fuel they do not participate to the reaction, but enable its complete execution while preventing aluminium passivation upon contact with oxygen contained in the water.

[0014] Many other processes for producing gaseous hydrogen from water have been studied over the past century, including reactions involving magnesium, sodium, potassium, lithium, calcium, iron, zinc, or steel.

[0015] Although the state-of-the-art hydrogen production processes have undeniable merits, until today the reaction of ordinary aluminium with water to release gaseous hydrogen and heat at ambient pressure and temperature, without external energy sources or catalysts, has never been provided, observed, or disclosed by prior inventors or researchers.

[0016] The energy transition, to be successfully achieved, requires abundant and low-cost resources such as recycled aluminium from selective waste collection, indicated as secondary aluminium. As previously mentioned, this form of reactant has never been the subject of patenting, nor have technologies been developed to address the main known issue that limits its use, namely the formation of a surface layer of AI2O3, which prevents the reaction with water itself.

[0017] Presentation of the invention

[0018] The primary object of the present invention is to overcome the widely recognized drawbacks in the known art and to be able to achieve this goal, this patent describes and claims a system and a series of processes based on an approach previously overlooked: i.e. the electrochemical approach. As extensively described, the previously adopted approach has been exclusively chemical, albeit through different methodologies. Aluminium has been treated as a reactant, shredded, pulverized, or alloyed with other rare earth elements, and however pre-treated, just like the reaction water, to which an alkaline metal salt is added or heated or vaporized. These measures, even when partially implemented, have not solved the issue or are too costly and difficult to carry out.

[0019] Among its chemical properties, aluminium has the ability to oxidize by donating electrons. Actually, in an electrochemical system of anode-cathode in an aqueous electrolyte, known as a metal-air battery, the reaction is as follows:

[0020] Anodic reaction: Al + 3(O / f)- -> Al(0H)2+ 3e~

[0021] Cathodic reaction: O2+ 2H2O + 4e~ -> 40 H~ this creates a potential difference that increases the system energy, i.e. polarizing the aluminium, which, instead of passivating, reacts with the OH~ ions generated by oxygen reduction, forming aluminium hydroxide and gaseous hydrogen according to the following: heat

[0022] Unlike the prior art, the hydroxide ions are not supplied by the dissociation of a strong base but are generated during the reaction by the reduction of the oxygen present in the material or component acting as the cathode.

[0023] In addition to the purely electrochemical characteristics just mentioned, aluminium has a high energy density, which, beyond the hydrogen produced, serves as a significant source of thermal power consistently released during this reaction.

[0024] The system of the invention describes and claims, in addition to the production and treatment of gaseous hydrogen from water splitting, also the transformation of heat into electrical energy through the use of a heat exchanger that powers a steam turbine operating on the Rankine cycle.

[0025] The invention encompasses a system for producing hydrogen and thermal power through a spontaneous electrochemical oxidation-reduction reaction according to Claim 1 and a process for producing hydrogen and thermal power through an oxidation-reduction reaction according to Claim 8. Specific embodiments are the subject of the dependent claims, the content of which is to be considered forming part of the present description.

[0026] Description of the drawings

[0027] The system claimed herein to implement the processes of the present invention is schematically represented in Figure 1. It is a reactor 1 into which aluminium scrap is introduced via a loading system 2, and water is introduced through a loading line 3. The materials settle in a reaction basin 6 to come into contact with a cathode body 5 and a grid 16 so as to separate the hydroxide during the reaction, which, due to its powdered consistency, falls into a discharge body 12. The cathode body 5 consists of a porous material rich in oxygen, which is supplied with oxygen or enriched material through a line 4. The heat produced by the reaction is transferred to a separate hydraulic circuit equipped with a heat exchanger 9, which powers a steam turbine 10 that supplies an electric generator 11. The hydrogen produced from the water splitting reaction in the reactor 1 passes through a sponge filter 7 located at the top of the reactor 1 and is directed to storage or to user through a discharge line 8. The hydroxide formed during the aluminium-water reaction in the basin 6 of the reactor 1, due to its basic nature, will fall into a neutralization chamber 12 through the grid 16, wherein it is neutralized by contact with an acidic solution introduced via a line 13. The progress of the neutralization reaction is monitored by a pH sensor 14, and once the desired pH is achieved, the hydroxide is safely discharged through a discharge line 15.

Claims

CLAIMS1. A system for producing hydrogen and thermal power by a spontaneous electrochemical oxidation-reduction reaction, formed by:- at least one reactor (1) composed of a loading line (2) which introduces a reacting material into a reaction basin (6) wherein all the elements belonging to the reaction are in contact;- at least one discharge body (12) wherein the hydroxide produced by the reaction enters by gravity through a grid (16) wherein the pH is transformed into a desired value by introducing an acid solution from a loading line (13), a pH sensor (14) being arranged for reading the instantaneous pH value, and a discharge line (15) for the escape of the hydroxide once the desired pH value has been reached,- at least one loading line (3) for water that is introduced into the reaction basin (6);- at least one cathode body (5) composed of porous material containing oxygen gas;- at least one charging line (4) that allows the oxygen to be recharged at the cathode body (5) once exhausted;- at least one filter of porous material (7) to separate the gaseous hydrogen from solid residues produced during the reaction; and- at least one exhaust line (8) for the escape of hydrogen gas.

2. The system for producing hydrogen and thermal power according to claim 1, composed of a heat exchanger (9) to be able to transmit the thermal power generated by the reaction occurred in the reactor (1) to an external circuit connected to a steam turbine (10) which, in turn, is connected to a generator (11).

3. The system for producing hydrogen and thermal power according to claim 1 , wherein the material (2) is non-shredded, non-pulverized recycled aluminium.

4. The system for producing hydrogen and thermal power according to claim 1, with a body acting as a reaction basin (6) which is in contact with the cathode body (5), with the material introduced from the line (2) acting as anode, with the water introduced from line (3) acting as the electrolyte.

5. The system for producing hydrogen and thermal power according to claim 1 , wherein the cathode body (5) is adapted to be fed by the charging line (4) of oxygen or material containing it.

6. The system for producing hydrogen and thermal power according to claim 1 , wherein the discharge body (12) acting as a neutralization chamber is fed with an acidic aqueous solution from the loading line (13), said solution being introduced either manually or in automated way by reading the desired pH value from the sensor (14), the neutralized hydroxide being expelled from the discharge line (15).

7. The system for producing hydrogen and thermal power according to claim 1 , wherein the filter of porous material (7) can be made of sponge or other material adapted to separate the gaseous hydrogen from solid residues produced during the reaction, the hydrogen thus filtered being conveyed towards the user through the discharge line (8).

8. A process for producing hydrogen and thermal power through an oxidation-reduction reaction between a material acting as an anode, a material acting as a cathode and a material acting as an electrolyte, according to the following steps:- Introducing a metal acting as an anode into the reactor (1) through a loading line (2) into a reaction basin (6);- Introducing water acting as electrolyte from a load line (3) into the reaction basin (6) so as to cover a heat exchanger (9);- Introducing oxygen, or material rich in it, into a cathode body (5) through a load line (4)- Start of a reaction in the basin (6), exit of the hydrogen gas through an exhaust line (8) through a porous filter (7);- Transmission of a thermal power produced by the reaction through the heat exchanger (9), implementation of a Rankine cycle by a turbine (10) and use of the work by a generator (11);- End of the reaction in the basin (6), complete fall of the aluminum hydroxide into a discharge body (12) through a grid (16);- Reading of the pH value of the hydroxide contained in the body (12) by a sensor (14);- Introducing an acid solution through a loading line (13) into the discharge body (12);- Reading the pH value by the sensor (14) and introducing the acid solution from the line (13) until the desired pH value, called normalized, is obtained; and - Expulsion of aluminum hydroxide and water from the discharge line (15).

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