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INVENTION
Russian Federation Patent RU2260880

STORAGE AND HYDROGEN PRODUCING hydrolysis of aluminum for autonomous power plants electrochemical generator

Name of the inventor: Avakov VB (RU); Zinin VI (RU); Ivanitskii BA (RU); Fists GV (RU); Landgraf IK (RU)
The name of the patentee: Federal State Unitary Enterprise "Central Research Institute of Ship Electrical Engineering and Technology" (FSUE "CRI SET") (RU)
Address for correspondence: 196128, St. Petersburg, ul. Grace, 6, Federal State Unitary Enterprise "Central Research Institute of SET," the deputy. Director VB Avakov
Starting date of the patent: 2003.06.30

The invention relates to the field of autonomous power, mainly to energy installations with electrochemical generators. According to the invention, a method of storing and producing hydrogen in autonomous power plants with a cycle of operation from a few hours to a few thousand hours, especially for submarines, underwater vehicles, ships, rail and road transport, domestic energy sources batch and periodically operating stationary power plants, used in especially critical sites that do not allow interruption of power, including the production of hydrogen by hydrolysis of aluminum. As starting components are used in the form of aluminum foil, sheet, wire, granules, regular or irregular, with the proviso that one of the linear dimensions of the mold used does not exceed 2.1 mm, and water vapor. In power plants with low autonomy, to several hours, hydrolysis is carried out at a temperature of 250-300 ° C, the container is applied a method of storing and replacing the spent whole container. In power plants with more autonomous process carried out at 200-250 ° C, and the applicable non-removable or exchangeable containers and removal of reaction products from the container irremovable effected by suction from the container oxide or Al oxide dissolving chemical reagents and discharge of the reaction products, followed by washing and dewatering . Regulating the flow of hydrogen produced is carried out by controlling the amount supplied in the form of water vapor. The technical result - increasing process efficiency, lower cost of hydrogen production and elimination of the need for aggressive media during operation and improving direct release of hydrogen, the hydrolysis is carried out with water in the vapor phase.

DESCRIPTION OF THE INVENTION

The invention relates to self-contained power plants, mainly from the electrochemical generators.

A distinctive feature of the stand-alone power plants (PP) is the frequency of operation for a relatively short period of time, the duration of which is determined by the inventory of reactants (fuel and oxidizer).

These include the installation of power plants for submarines, underwater vehicles, ships, rail and road transport, domestic energy sources batch, and batch and stationary power plants that are used on the most responsible sites that do not allow interruption of power supply.

A method of storing and producing hydrogen in autonomous power plant should provide long-term and safe storage and safe and its reception at the minimum cost, weight and volume of the storage system and the production of hydrogen, the simplicity of operation of power plants and disposal of the reaction products.

Known methods for storing and producing hydrogen for independent power plants (see. N.S.Lidorenko, G.F.Muchnik "Electrochemical generators", M., 1982 .; N.V.Korovin "Electrochemical Energy", Moscow, Energoatomizdat, 1991):

- Storing in the gaseous state, in which hydrogen is stored in high pressure vessels (up to 50 MPa) and after throttling is fed to the electrochemical generator (ECG);

- Storing liquid (cryogenic) hydrogen, wherein before entering the ECG gasified;

- Storing composed of intermetallic compounds, which it previously sorbed, and before entering the ECG is desorbed from the absorption of heat;

- Storage of hydrogen in a chemically bound state, composed of hydrogen-containing compounds, when hydrogen is produced by the respective chemical process.

By the latter method of hydrogen production and storage are:

- Storage of hydrogen in the composition of ammonia and to obtain it by dissociation;

- A hydrogen storage composition of methanol and other liquid hydrocarbons and its receipt by steam or steam-oxygen their conversion;

- Storage of hydrogen in metal hydrides composition and its preparation by thermal decomposition;

- Storage of hydrogen in metal hydrides, and the composition of water and its preparation by hydrolysis of metal hydrides.

None of the above methods of storage and production of hydrogen does not meet all requirements for storage and production of hydrogen for stand-alone power plants.

The most safe and easy to use way to store in the intermetallic compounds, but it is expensive to manufacture and determines the greater mass power plant, since the cost of 1 kg of the intermetallic compound is $ 15-35, and mass hydrogen capacity widely applied sorbents is only 1.5-2.0% .

The lowest weight and volume of installation with sufficient level of security can be obtained from the conversion of methanol or hydrocarbon fuel, but are inevitable gaseous reaction products, which in some cases are not permitted (in submarines and other similar objects), as can lead to loss of secrecy.

Known methods for producing and hydrogen by reacting water with aluminum and magnesium.

Hydrolysis of water in the presence of aluminum alkali is one of the following reactions below:

The mass yield of hydrogen according to reaction (1) is about 1.5%, and the reaction product is insoluble in water, so further consideration of the reaction (1) is not interesting.

The mass yield of reaction (2) theoretically reaches 3.5%, the reaction product is sparingly soluble in water, so to allow the subsequent removal of the reaction products after the completion of their life cycle are usually stored in the form of a solution, to which additional water is required, which can reduce the mass hydrogen yield of 1.5-2%.

This, taking into account the irreversibility of the process, making the reaction (2), and uninteresting.

Magnesium water hydrolysis may follow the reaction:

Mass hydrogen yield was 3.3% and the reaction product is insoluble in water.

The present invention is directed to avoid the use of corrosive media during direct operation and a significant increase in the weight percent of hydrogen produced relative to the total weight of the initial reaction product, provided that the completion of the outside starting materials, such as water, and discharge of the reaction products in the period of autonomy, - absent it is very important to ensure the secrecy of the object equipped with a power plant with ECG.

Experiments have shown that the process can be carried out by reaction other than (1 and 2) under specific conditions, namely:

As a result of the reaction of aluminum with water gives a pure aluminum oxide and hydrogen. The mass yield of hydrogen is 5.5%, but when you consider that the need for the reaction, the amount of water is small and still generated in the ECG during operation ET, then when using mass hydrogen yield reaches 11.5%.

A prerequisite implement (4) is to supply water in the vapor phase, in the form of saturated or superheated steam in a quantity close to stoichiometry. At the same time the amount of hydrogen is regulated by the amount of water supplied.

Aluminum may be used in any form of foil, sheet, wire, granules, regular and irregular, etc. It is important to maximize the reaction surface and its completeness.

In both cases, this implies that one of the linear dimensions of the mold used is sufficiently small and does not exceed 1.2 mm.

The level of temperature at which the reaction is advantageously carried out, and a method of storing and starting materials and the method for replacing the initial reaction products depend on the type and assign it to the power plant.

In power plants with relatively little autonomy, not exceeding a few hours, such as EC motor, it is advisable to use the storage container and the replacement method, and the reaction is carried out at a temperature of 250-300 ° C. In this method, aluminum foil, sheet, wire, granules, regular or irregular placed in special containers, into which the alumina oxidation reaction of steam with vigorous evolution of hydrogen. After all of the aluminum in the container will react with steam and in turn alumina is extracted from the installation vessel and is sent to a specialized company, and the place of the spent container with a new container installed by aluminum.

In power plants with great autonomy of tens, hundreds and thousands of hours (for example, in power plants submarines) for the storage of aluminum along with interchangeable containers can be used non-removable containers (storage), and Al oxidation reaction is enough to lead at 200-250 ° C. Thus the removal of the reaction products (alumina) from a stationary storage can be carried out in basic conditions in the following schemes:

- Alumina suction from the container, followed by washing with water and drying the container;

- Dissolution of alumina followed by chemical reagents discharge reaction products by washing and drying the container.

After purification of the reaction product container filled with a fresh portion of Al, which is suitable for use in the form of pellets or in any other form that provides the material flowability and the absence of fine dust that can lead to spontaneous ignition.

In order to ensure the start of the reaction (4), it is necessary to receive the steam and heat the aluminum to a predetermined temperature. For this purpose can be used, for example, any electrical device (a heating, electric discharge or the like) fed from the base or from the source or sources on the board. Since the reaction is highly exothermic, it is important synitsiirovat continue to maintain the required temperatures by the removal of excess heat.

To reduce the preparations for the hydrolysis reaction of aluminum energy costs (production of steam and heated to a predetermined temperature Al) aluminum partition advisable storage and have one or more "glow" sections. Thus initially it heats only the "glow" section, and then released by it as a result of the heat of reaction heated others.

CLAIM

1. A method for storing and producing hydrogen in autonomous power plants, including plant with electrochemical generators with operation cycle from a few to thousands of hours, mainly for power plants submarines, submersibles, road transport and periodically operating stationary installations that are used on the most responsible objects that do not allow interruption of power, comprising the production of hydrogen by hydrolysis of aluminum, characterized in that the hydrolysis is carried out of aluminum when water vapor in the form of saturated or superheated steam at a temperature of 200-300 ° C in an amount close to the stoichiometric according to the reaction which ensures the maximum mass yield of hydrogen.

2. The method of claim 1, wherein the aluminum in the hydrolysis reaction using water generated in an electrochemical generator.

3. A method according to claim 1, characterized in that for the generation of steam and heating the aluminum to a predetermined temperature using the heat generated by the hydrolysis of aluminum.

4. A method according to claim 1, characterized in that the flow control is provided by the hydrogen produced by controlling the amount applied to the reaction of water vapor.

5. The method of claim 1, wherein the preparation for reduction of energy consumption for conducting the reaction is partitioned storage aluminum and one or more sections are used as "glow."

6. A method according to claim 1, characterized in that for a relatively small power plants with autonomy, not exceeding a few hours, preferably automobile, the hydrolysis process is conducted at a temperature of 250-300 ° C, while in the form of aluminum foil, sheet, rolled, or granules regular or irregular, in which one of the linear dimensions of the mold used does not exceed 1-2 mm and placed in special containers, easily removable, which after completion of the reaction are extracted from the plant and sent to alumina refining to a specialized company, and in their place installed new containers aluminum.

7. The method according to claim 1, characterized in that for power plants with a relatively large autonomy of tens, hundreds and thousands of hours, preferably for power plants for submarines used for storing aluminum exchangeable containers (storage), and the hydrolysis process is carried out at a temperature 200-250 ° C, with removal of the reaction products (alumina) made of non-replaceable containers in the basic process conditions monoxide suction from the container or dissolving chemical reagents oxide with discharge from the container, followed by washing and drying and loading with new aluminum portions as any form of granules, wherein one of the linear dimensions of the mold used does not exceed 1.2 mm, ensuring the flowability of the material.

print version
Publication date 04.01.2007gg