Method of producing and storing hydrogen in autonomous power systems

 

(57) Abstract:

The invention relates to a battery energy, in particular to a method of producing and storing hydrogen in Autonomous power systems with cycle operation from tens to thousands of hours mainly for submarines. According to the invention the method includes obtaining hydrogen by generating steam by passing it through a sorbent consisting of iron catalyst and the oxidation reaction of iron. As one of the starting components of the reaction is water, which is formed by the reaction of power generation in the ECG. In addition, Autonomous airindependent plants to generate steam required for zheltoyarovo method of producing hydrogen can be used heat exothermic decomposition reaction of a substance (e.g., hydrogen peroxide) containing oxygen. For even feeding of the hydrogen oxidation reaction of iron is carried out with a variable (increasing) during the process temperature, for complete oxidation of iron and its subsequent recovery use volume structures density of 4-6 g/cm3of compacted fine iron, providing DOS the population of hydrogen in the running section sequentially connect the new section. A combination of these methods. Recovery of the oxidized iron is carried out in an Autonomous power plant hydrogen, carbon monoxide or mixtures thereof. The technical result of the invention is the provision of safety and duration of storage of hydrogen. 3 C.p. f-crystals.

The invention relates to the field of Autonomous energy, namely, the field of producing and storing hydrogen stand-alone power plants preferably with electrochemical generators (ECG).

A distinctive feature of Autonomous energy units (EU) is the frequency of operation for a relatively short time, the duration of which is determined by the stocks of the reactants (fuel and oxidant).

Such power plants can be installed for submarines, underwater vehicles, ships, rail and road transport, domestic energy sources of periodic action, as well as occasionally acting as a stationary power plant used in the most important objects that do not allow the power interruption.

Method of producing and storing hydrogen stand-alone power plant must provide a safe polycrylene and storage of hydrogen, the simplicity of the operation of EC and disposal (or regeneration) of the reaction products.

Known methods of producing and storing hydrogen for Autonomous power plants (see N.With. Sidorenko, G. F. Muchnik "Electrochemical generators, Meters, 1982):

- storage in the gaseous state, where the hydrogen is stored in vessels under high pressure (50 MPa) and then supplied to the throttle ECG;

- storage in the liquid state (cryogenic) when hydrogen before being gasified in the ECG;

- storing in the intermetallic compound, in which it is pre-adsorbed, and before entering the ECG is desorbed from the absorption of heat;

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

The last method of producing and storing hydrogen include:

- storage of hydrogen in the ammonia and its preparation by dissociation;

- storage of hydrogen in the methanol and other liquid hydrocarbons and getting it through steam or steam-oxygen conversion;

- storage of hydrogen in the metal hydride and receiving it by termicheskoj is of reeds metals;

- storage of hydrogen in water composition and its preparation by reacting a magnesium alloy or aluminum.

None of the above methods of storing and producing hydrogen does not satisfy all the requirements of the production and storage of hydrogen stand-alone power plant.

The most secure and user-friendly way of keeping in intermetallic compounds, but it is costly to manufacture and determines the larger mass of the EC, because the cost of 1 kg of intermetallic is 15-35 $, and mass capacity found wide application of sorbents is only 1.5 to 2.0%. The smallest mass and volume setup with a sufficient level of security can be obtained using the conversion of methanol or hydrocarbon fuel, but it is inevitable, gaseous reaction products, which in some cases is invalid (on submarines and other similar objects), because it can lead to the loss of stealth.

The issue of secrecy when a sufficient level of safety and optimum weight and performance can be realized using the method of storing hydrogen in the water and getting it as a result of hydrolysis using metal hydrides, alloys of magnesium and aluminum, but the treatment of hydrogen by the interaction of water vapor with iron at high temperatures, which was opened Lavoisier in 1783 Iron-steam method of producing hydrogen is through the sorbent, consisting of fine iron, skipping superheated steam with a temperature of 200-1000oC. the higher the temperature, the lower is the equilibrium concentration of hydrogen in the steam-water mixture, but the higher the reaction rate.

Interaction of iron with steam is carried out according to the following reactions:

Fe+H2OFeO+H2(1)

3Fe+4H2OFe3O4+4H2(2)

2Fe+3H2OFe2O3+3H2(3)

First reaction you can produce 0.4 l H2/g Fe (3,56 wt.%), on the second one, respectively 0,53 l H2/g Fe (4.7 wt.%), and on the third - 0.6 l H2/g Fe (5.3 wt. %). All three reactions of weakly ectothermic, however, taking into account the cost of heat required to produce steam, the steam-iron the method of producing hydrogen requires energy, however, the magnitude of these costs is small and when the proper organization of the process (the use of heat recovery) is equivalent to the energy released in the oxidation of 10-12% of the produced hydrogen.

Recovery of iron oxides obtained by reactions 1, 2, 3, can be hydrogen or a mixture of hydrogen with monoxi
FeO+COFe+CO2(4)

Fe3O4+CO3FeO+CO2(5)

Fe2O3+CO2FeO+CO2(6)

Reaction 4 is weakly endothermic reactions 5 and 6 is slightly exothermic.

The beginning of the practical application of iron-steam method should be attributed to 1794 in France. Hydrogen was produced in cast-iron retorts, filled with iron filings. After heating to red heat is passed through water vapor. The resulting hydrogen is used to fill the balloons. Further development of the iron-steam method received after zhilar in 1846 was to restore the iron oxide gas generator. At the end of the 19th century and the first quarter of the 20th century, the steam-iron process was one of the most common methods of producing hydrogen.

However, the steam-iron process of hydrogen production was intermittent, low productivity, the recovery of oxides often consumed hydrogen. This has resulted in the need to obtain large quantities of hydrogen there are new, more advanced methods of industrial production of hydrogen, such as coal gasification, and from the middle of this century - steam-oxygen conversion of natural gas, which totally is the n development of new modified versions of the continuous steam-iron process for the industrial production of hydrogen. In the application Germany 4226496 A1 from 11.08.92 proposes a method of producing hydrogen at a temperature of 850 To the steam-iron process. Iron comes in the form of iron scrap and reacts with water vapor in a conventional blast furnace. The process is continuous. The resulting gas contains 60% N2and 40% H2O. the Resulting oxides are derived from the shaft furnace and sent to recovery, which is a gas mixture containing CO, such as the conversion of gas. The hydrogen in the process can be selectively released by means of molecular sieves. In the process, an additional stage of oxidation of FeO to Fe2ABOUT3the oxygen. This is an exothermic reaction and heat due to the heat used to obtain necessary additional steam for the steam-iron process.

In the Federal Republic of Germany patent 1242193 from 1967 proposed a two-stage continuous method of producing high purity hydrogen. Oxidation of finely divided iron is steam at high temperature and pressure. Iron is oxidized mainly to FeO. Recovery FeO is gaseous methane. When restoring receive a mixture containing 60-95% Fe and about 5% FeO. Temperature recovery 600-850o
3F203+ h = 2F2O4+ 0.5 O2.

Of considerable interest is thesis of A. H. Krause (Kontinuerliche Erzeugung von Wasserstoffnach Eisen-Dampf-Prozess. Dissertation RWTH Aachen, 1989). It discussed in detail the physico-chemical aspects of the steam-iron process for producing hydrogen and proposed a continuous method of implementation. In the journal "Energietechnik", 1978, 28 11, S. 407-413 presented engineering challenges of large-scale hydrogen production-steam iron method.

Thus, the whole history of the development of industrial steam-iron method of producing hydrogen is aimed at achieving the continuity of the generation process. Known also suggestions for using the steam-iron method of producing hydrogen for independent power plants.

Thus, in U.S. patent 5629102 from 1997 offered a car with ECG. The hydrogen produced by the fuel station car that uses iron-steam method. After oxidation of the iron reaction products are discharged to the specialized service stations, and in return, the reactor is loaded a new piece of hardware.

Similar plant for hydrogen production and regeneration described in patent productivity in relatively short periods of time (more than several hours). The main thrust of the proposals is the reduction of the temperature of hydrogen generation due to the use of catalysts and the removal of the generation of iron outside the power plant. The proposals relate to the self-energy installations with a short cycle operation (no more than a few hours), which is typical for most cars.

This proposal relates to the self-energy installations with long cycle operation - from tens to thousands of hours, especially plants for submarines and underwater vehicles. For this type of installation is characterized by the mass of the reagent (iron) is many times greater than the mass of the actual plant, so the removal of the generation of iron outside the power plant is of little use. In addition, the organization of separate bins for storing freshly loaded and unreacted iron leads to the loss of useful volume. Therefore, for systems with long cycle operation the regeneration of iron are proposed to be implemented in the power plant.

Conducted by the authors showed that the completeness of the reaction of iron with adequate functioning of physical alteration of catalysts. First of all, you need to provide access to the steam iron responsive and have a reasonable amount of storage. For this purpose a mixture of iron powder with a catalyst suitable press to a density of 4-6 g/cm3(which ensures the necessary porosity), choosing the form of pressed pellets so as to guarantee access to the steam anywhere tablet to a depth of not more than 2 mm. in Addition, studies have shown that the rate of hydrogen in the reaction mix, and falls with decreasing the amount of unreacted iron. To maintain the necessary vodorodopronitsaemosti during the entire cycle of operation of the installation, you can use the separation of the storage section and the serial connection of new sections at least reduce the rate of hydrogen generation to the previously included in the work or increases in temperature generation with 200-300oWith the beginning of the process up to 500-600oIn the end, or a combined method that combines both methods, i.e., strategy connect and temperature increase with decreasing the amount of unreacted iron.

The analysis of the properties of the steam-iron process for hydrogen shows the, than those used to date methods. It provides safe production of hydrogen, as well as long-lasting and safe storage. According to these parameters is not inferior to, and even surpasses the known safe way to store hydrogen stand-alone installations in intermetallics. When this dispersed iron powder is much cheaper than the sorbents type La-Ni or Fe-Ti, and the required mass and volume are much smaller than those of these intermetallic compounds, since the mass capacity of hydrogen is about 5% against 1.5-2%, and the density in the compressed state may be 4-6 g/cm3. The reaction products are pure hydrogen and oxides of iron, which is easily regenerated and can be reused up to 10,000 times according to the experience of industrial applications. Thus, the original product is finely dispersed iron can be incorporated into the system once for the entire lifetime of the installation. For another source component of the process water is not required reserve mass and volume in stand-alone power plant, as formed during the reaction in the ECG or other device, water sufficient for these purposes.

Especially it is the issue of heat consumption for the production of CSOs using heat released in the ECG or other device, the regeneration heat generated hydrogen, the total number of additional quantity of heat that must be supplied externally for steam generation, is relatively small and can be compensated by burning about 10% of the produced hydrogen.

In addition, Autonomous airindependent installations, where the obligatory initial reactant is oxygen, the latter can be stored in chemical compounds (e.g. hydrogen peroxide), the decomposition reaction which is exothermic, and the resulting decomposition heat can be used to generate the steam required for the organization of the steam-iron method of hydrogen storage.

1. Method of producing and storing hydrogen in Autonomous power systems with electrochemical generator, generating electricity and water, including vozduhonezavisimymi obtaining oxygen by decomposition of oxygen-containing substances, with a cycle of operation from tens to thousands of hours, preferably for submarines, including the production of hydrogen by generating steam by passing it through a sorbent consisting of iron catalyst and conducting Roy from 2 to 4 mm of compacted iron catalyst density of from 4 to 6 g/cm3in storage; the reaction of iron oxidation is carried out with increasing process temperature and the regeneration of the oxidized iron is carried out in the Autonomous power plant by carrying out reduction reaction of iron with hydrogen, carbon monoxide or mixtures thereof.

2. The method according to p. 1, characterized in that the storage is divided into sections of iron and at least reduce the rate of hydrogen employed in the sections sequentially connect the new section.

3. The method according to p. 1, characterized in that for generating steam using the water produced by the self-contained power unit.

4. The method according to p. 1, characterized in that the reaction of hydrogen generation in airindependent power plants use the heat of the exothermic decomposition reaction of oxygen-containing substances.

 

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SUBSTANCE: catalyst for generation of synthesis gas via catalytic conversion of hydrocarbons is a complex composite composed of ceramic matrix and, dispersed throughout the matrix, coarse particles of a material and their aggregates in amounts from 0.5 to 70% by weight. Catalyst comprises system of parallel and/or crossing channels. Dispersed material is selected from rare-earth and transition metal oxides, and mixtures thereof, metals and alloys thereof, period 4 metal carbides, and mixtures thereof, which differ from the matrix in what concerns both composition and structure. Preparation procedure comprises providing homogenous mass containing caking-able ceramic matrix material and material to be dispersed, appropriately shaping the mass, and heat treatment. Material to be dispersed are powders containing metallic aluminum. Homogenous mass is used for impregnation of fibrous and/or woven materials forming on caking system of parallel and/or perpendicularly crossing channels. Before heat treatment, shaped mass is preliminarily treated under hydrothermal conditions.

EFFECT: increased resistance of catalyst to thermal impacts with sufficiently high specific surface and activity retained.

4 cl, 1 tbl, 8 ex

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